API 参考

Route action: handles form submissions for a page route.

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Context passed to a route action function (extends loader context).

formData: FormData (必填); request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Wire shape returned to the JavaScript form-enhancement path. The no-JS path never sees this: it gets the equivalent semantics as plain HTTP (303 on success, 422 with the re-rendered form on validation failure, redirect/error as status codes). Success carries no data envelope. The application-loop contract makes a successful non-GET action answer 303 (PRG) — the framework never answers 200 with a rendered page, or with a success document, for a successful mutation — so the fetch channel answers `{ type: 'redirect' }` naming the PRG target and the authored return value is discarded by design. Success data travels the PRG target instead (query state the loader re-runs with, which the props projector then maps; see the router guide's "Form actions" section). The union previously declared a `{ type: 'success' }` member that no code path ever emitted — removed so the type matches the wire. Error outcomes (CSRF 403, unknown action 404, unparseable body 400, unexpected 500) are NOT part of this union: since #863 they answer RFC 9457 Problem Details with the PROBLEM_JSON_MEDIA_TYPE content type — see ProblemDetails.

One API route declaration in the generated entry descriptor.

kind: "api" (必填); path: string (必填); varName: string (必填); filePath: string (必填); importPath: string (必填)

Application shell declaration: `false` disables the shell entirely, `'default'` uses the built-in shell, and the object form names a tag with the module path that defines it (`import`, resolved like a {@link FrameworkOptions.middleware.use } entry) plus the compiled shell properties the router injects per route.

The app shell module a build resolves: tag, import path, and serialized props.

tagName: string (必填); importPath: string (必填); props: Record<string, unknown> (必填)

The resolved app shells a build ships: the default shell plus named layouts.

default: ResolvedAppShell (必填); layouts: Record<string, ResolvedAppShell> (必填)

Attribute/authoring-surface failures (phase `validation`).

Result returned by the OpenElement build pipeline.

pages: BuildPageArtifact[] (必填) — Generated HTML pages.; manifest: BuildManifestArtifact (必填) — Build manifest.; clientAssets: BuildClientAsset[] (必填) — Client-side assets (island bundles, CSS, etc).; warnings: string[] (必填) — Non-fatal warnings.; errors: string[] (必填) — Fatal errors.; success: boolean (必填) — Whether the build succeeded.

A single client asset emitted by the build pipeline.

fileName: string (必填); source: string | Uint8Array<ArrayBufferLike> (必填); sizeBytes.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; sizeBytes.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; sizeBytes.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; sizeBytes.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; sizeBytes.valueOf: () => number (必填) — Returns the primitive value of the specified object.; sizeBytes.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

i18n configuration for the build pipeline.

locales: string[] (必填); defaultLocale?: string (可选)

A single island input to the build pipeline.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); hydrate?: IslandDeliveryStrategy (可选); ssr?: boolean (可选); dsd?: boolean (可选); source?: "local" | "package" | "nested" (可选); reason?: string (可选)

Manifest produced by the build pipeline.

routes: { kind: "page" | "api"; path: string; tagName?: string; isDynamic: boolean; }[] (必填); islands: BuildIslandInput[] (必填); requestTimeRoutes?: string[] (可选) — Paths served at request time (renderIntent mode 'dynamic'). Absent for pure-static builds.

Output configuration for the build pipeline.

root?: string (可选) — Project root directory.; outDir?: string (可选) — Output directory relative to root.; base?: string (可选) — Base URL path.

Package island configuration for the build pipeline.

packages?: string[] (可选) — Package names that may expose island declarations.

A single generated HTML page artifact.

path: string (必填); html: string (必填); errors: { message: string; route?: string; }[] (必填) — Errors collected while rendering this page.

Framework-agnostic plan consumed by the OpenElement build pipeline.

options.renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; options.routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; options.islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; options.componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; options.packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; options.appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; options.layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; options.mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; options.headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; options.html?: { lang?: string; title?: string; } (可选) — Document `<html>` attributes: the `lang` the document declares and the default `<title>`.; options.inject?: { stylesheets?: Array<string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | bool… (可选) — Document head/body injection channels: external stylesheets, scripts, and trusted raw head fragments.; options.ssr?: { noExternal?: (string | RegExp)[]; } (可选) — SSR bundling switches; `noExternal` forces the named packages through the SSR bundle instead of an external import.; options.island?: { upgradeStrategy?: HydrationStrategy; } (可选) — Island defaults applied to every island the build discovers.; options.build?: { outDir?: string; manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; }; } (可选) — Build output switches: the output directory and the advisory manifest budgets.; options.viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; options.speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; options.middleware?: { cors?: boolean; corsOrigin?: string | string[]; corsOriginModule?: string; requestId?: boolean; logger?: boolean; securityHeaders?: boolean; csp?: { policy?:… (可选) — Request-time middleware switches, composed outside the framework handler.; routes: BuildRouteInput[] (必填) — Discovered page and API routes.; islands: BuildIslandInput[] (必填) — Discovered local and package islands.; output.root?: string (可选) — Project root directory.; output.outDir?: string (可选) — Output directory relative to root.; output.base?: string (可选) — Base URL path.; i18n?: BuildI18nOptions (可选) — i18n expansion options.; packageIslands.packages?: string[] (可选) — Package names that may expose island declarations.

A single route input to the build pipeline.

kind: "page" | "api" (必填) — Route kind: page or API.; path: string (必填) — Route path (e.g. '/about', '/blog/:slug').; filePath: string (必填) — Absolute or relative file path of the route module.; importPath: string (必填) — Import specifier used by generated entry code.; tagName?: string (可选) — Resolved tag name for page routes.; paramNames?: string[] (可选) — Dynamic segment names.; staticParams?: Record<string, string>[] (可选) — Static generation params produced by getStaticPaths().

The one camelCase → kebab-case casing rule for custom-element attribute names, so `<x-el itemCount={5}>` round-trips as `item-count` on every boundary that derives an attribute name from a prop name: the compiler's property metadata, the SSR serializer, and the client attribute handling.

The compatibility classification report for one custom element manifest.

totalClassified.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; totalClassified.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; totalClassified.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; totalClassified.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; totalClassified.valueOf: () => number (必填) — Returns the primitive value of the specified object.; totalClassified.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; ssrCapableCount: number (必填); clientOnlyCount: number (必填); rejectedCount: number (必填); experimentalDomCount: number (必填); classifications: CompatibilityClassification[] (必填); summary: string (必填)

One property entry of the compiled custom-elements-manifest metadata.

name: string (必填); fieldName: string (必填); type: PropertyValueType (必填); attribute: string | null (必填); reflect: boolean (必填)

Claim failures: the existing DOM does not match the program that would own it. The value shipped in 1.0.0-alpha.3 and is kept verbatim; consumers match on it, and `PartProgramClaimError` is its only raiser.

The Phase 2 client build's delivery manifest, keyed by island identity.

entry: string (必填) — The island client entry URL ('' when no client bundle shipped).; islands: Record<string, ClientIslandAsset> (必填) — Compile-time island identity (delivery tag) -> emitted asset.; shared: string[] (必填) — Shared chunk URLs emitted by the client build (JS, neither entry nor island-dedicated).; styles: string[] (必填) — Preloadable island style asset URLs, sorted, base-prefixed. Shadow-component CSS cannot be applied as a document-level stylesheet — it cannot reach shadow trees — so the document channel's only role for these URLs is preload; the sheets themselves are adopted through the sheet adapters.

The client asset one compile-time island identity resolves to.

file: string (必填) — Emitted asset URL (site-root relative, base-prefixed) of the chunk that carries the island module — its dedicated chunk, a shared chunk, or the client entry when the island has no chunk of its own.; strategy: IslandDeliveryStrategy (必填) — Delivery strategy resolved from the island declaration at build time.; preload?: boolean (可选) — True when the island's delivery strategy hydrates at load time, so the asset is a modulepreload candidate.

Client island entry shape passed to entry generator.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); exportName?: string (可选) — Optional named export to register as the custom element constructor. When set (package islands whose chunk dropped `export default` per #638), the client island factory reads `mod[exportName]` instead of `mod.default`. When absent, the factory falls back to `mod.default` (local/route islands).; strategy: IslandDeliveryStrategy (必填); strategySource?: "default" | "manifest" | "component" | "route" (可选); ssr?: boolean (可选); dsd?: boolean (可选); reason?: string (可选)

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

Version of the compiled-module ABI: the statics a generated module carries (`__partProgram`, `__compiledProperties`, `__elementMetadata`, `__observedAttributes`, `__computedFields`) and the runtime facade binds. Bump when the generated-module contract changes shape; generated artifacts stamp both this and PART_PROGRAM_VERSION so consumers can tell format drift from release drift. v2: platform lifecycle callback bodies are emitted inside a boundary-capture wrapper calling the base class's `_captureError` — a generated module now requires a runtime facade carrying that protected method (the v1 shape emitted the bodies verbatim).

The compiled custom-elements-manifest metadata block of one component.

tagName: string (必填); className: string (必填); declaration: { name: string; module: string; } (必填); attributes: { name: string; fieldName: string; type: PropertyValueType; reflect: boolean; }[] (必填); members: CemPropertyMetadata[] (必填)

The compiled element metadata the program carries for tooling consumers.

tag: string (必填); className: string (必填); sourceFile: string (必填); properties: CompiledPropertyMetadata[] (必填); observedAttributes: string[] (必填); cem: CompiledCemMetadata (必填)

One compiled

name: string (必填); attribute: string | null (必填); type: PropertyValueType (必填); converter: PropertyValueType (必填); reflect: boolean (必填); default: SerializableValue (必填); computed?: boolean (可选) — True for computed fields (`= computed(() => ...)` in the source): their signal is derived from other property signals by the generated `__computedFields` factory, never seeded from attributes/props. Always paired with `attribute: null` and `reflect: false`.; deps?: string[] (可选) — Source signal names a computed field reads (declaration order).

Compiler (build-time) failures. The per-diagnostic `OEC####` codes stay on each diagnostic; these classify the family so a build failure is catchable as one thing.

The delivery layer a component belongs to: fully static DSD markup ('dsd-static'), DSD markup with a client island ('dsd-interactive'), a client-only island with no SSR output ('pure-island'), or a light-DOM element ('light-dom'). Recorded per component in the build manifest and consumed by the hydration scheduler.

Operator/literal compatibility for when-Region tests (issue #1372). Both wire validators (this module and the server serializer's shared validator) close the space through this one predicate: - ordering operators require a finite numeric literal; - `equals`/`not-equals` admit a finite number, string, or boolean; - `truthy` admits exactly `true` or `false` (the recorded expectation).

The comparison operators a program condition supports.

Community-context service lifecycle failures (phase `csr`).

The CORS origin policy an API route declares.

The content-security-policy directives a route or document declares.

policy?: string (可选); nonce?: boolean (可选); reportOnly?: boolean (可选)

Internal SSR provenance marker on light-mode host tags (#1148). Present only when the host's light subtree was server-rendered under the in-place activation contract: the client binds the existing DOM instead of clearing it, and a parent's activation walk prunes the nested host's subtree. Client rendering never writes it and it is never removed. The writer (internal/compiled/server) and readers (internal/compiled/runtime) import this constant; nothing writes the literal.

Default code for {@linkcode RenderError }. Deliberately NOT a member of {@linkcode ErrorCode}: that object is the scan target of the documentation site's error catalog, which requires every member to carry a phase/severity family rule. `RENDER_ERROR` is the pre-dialect value `RenderError` has always defaulted to — kept verbatim so callers that observe it keep working, and kept out of the catalogue because it is not a failure this package classifies, only a constructor default a caller may override.

The document-level facts a build bakes into the generated entry.

lang: string (必填); title: string (必填); headExtras: string (必填); allowHeadExtrasScripts: boolean (必填)

Per-render declarative-shadow-dom metrics the server records.

tagName: string (必填); renderTimeMs.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; renderTimeMs.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; renderTimeMs.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; renderTimeMs.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; renderTimeMs.valueOf: () => number (必填) — Returns the primitive value of the specified object.; renderTimeMs.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; templateSize: number (必填); layer: ComponentLayer (必填); hasError: boolean (必填); nestingDepth: number (必填)

Keyed-list identity failures. Shared by the server serializer and the client runtime (see `internal/compiled/each-key.ts`), so both executors reject the same data with the same code.

The manifest a project without a client bundle carries.

Property on the stub holding the generated entry's registration-ownership map (tag -> class it registered): a route module that self-registers its tag wins over the entry's registration, and on dev re-evaluation a fresh self-registered class must still win (#952).

The full build-time description of one generated entry: routes, islands, renderers, middleware, document, and app-shell plans.

isSSG: boolean (必填); renderer?: "native" | "lit" (可选) — Page renderer selection (#1339). Absent/'native' keeps the compiled renderDsd page path byte-identical; 'lit' forks page tag resolution, page SSR and the client entry onto; imports: ImportDecl[] (必填); middleware: MiddlewareDecl[] (必填); fetchMiddleware?: string[] (可选) — `middleware.use` fetch middleware module paths (#858), in user-configured order. The entry renderer emits one `import * as __mw_N from '<path>'` per entry and composes each module's default export around the exported handler in onion order. Absent/empty when the app configures no fetch middleware, keeping the generated entry byte-identical to pre-#858 output.; apiRoutes: ApiRouteDecl[] (必填); pageRoutes: PageRouteDecl[] (必填); staticComponents: StaticComponentDecl[] (必填); islands: IslandDecl[] (必填); hasEnhancedForms?: boolean (可选) — True when any page route carries data-open-enhance forms (#569). Drives the dev island client script injection (#951): an island-free app with enhanced forms still needs the client entry in dev HTML.; ssrAdmissionPlan: SsrAdmissionPlan (必填); cemClassifications?: CompatibilityClassification[] (可选); renderers: RendererDecl[] (必填); middlewareScopes: MiddlewareScopeDecl[] (必填); document: DocumentConfig (必填); appShell: AppShellPlan (必填); upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); i18n?: { locales: string[]; defaultLocale: string; } (可选) — Declared project locales. Absent for a single-locale site: the generated entry then emits no locale prefixes and the default-locale fallback, which is byte-identical to pre-i18n output.

Error message prefix for all openElement errors.

Well-known error code constants for reference. String values are always accepted.

The pipeline phase an error was raised in.

How severe a framework error is.

Callback receiving every reported {@linkcode OpenElementError} for telemetry.

SSR/bootstrap failures raised by the public entries (phase `ssr` / `csr`).

Forbidden sink names — the ONE canonical deny list for every Part Program boundary: the compiler semantic core, the protocol validator (internal/protocol/part-program.ts), and the compiled server/claim validator (internal/compiled/server/shared.ts). This module is import-free and host-free by design (same base-of-graph contract as void-tags.ts): all consumers import it, so a new forbidden sink cannot be enforced on one boundary and missed on another. This module owns the named-sink deny lists and the attribute-name policy built on them (the one shared safe-attribute-name predicate and the one camelCase→kebab-case casing rule); consumers delegate so the boundary cannot diverge. The lists are fail closed and case-insensitive (attribute and property names are compared lowercase, matching the HTML parser's name folding): - `FORBIDDEN_ATTRIBUTE_NAMES`: attribute names that must never be a static attribute or an `attr`/`bool` sink. `srcdoc` smuggles a full HTML document past attribute escaping; `innerHTML` is admissible only through the dedicated trusted-HTML `html` Part, never as a plain attribute name. - `FORBIDDEN_PROPERTY_NAMES`: `prop` sink names that would re-prototype or re-construct the target element (prototype-pollution primitives). - `RAW_TEXT_TAGS`: raw-text elements are outside the compiled grammar — their content cannot be escaped by the serializer.

Property names the compiler refuses as

Sink categories the canonical deny list classifies.

Return a human-readable reason when `name` is a forbidden sink of `kind`, or null when the name is admissible. Unknown kinds fail closed with a reason instead of being waved through.

One framework failure: {@linkcode OpenElementError} with the caller's code and the phase/severity/recoverability that phase implies. Every throw site in this package goes through this factory (or the `*ErrorCode` tables above) so a code, a phase and a recoverability answer cannot drift per site.

The adapter-facing framework options: where routes, islands and components live, which renderer serializes pages, the application shell and layout declarations, the document `<html>`/head injection channels, and the request-time middleware switches. Every field is optional; the adapter applies its documented default. This is the type an application config file's default export is checked against, so the rendered option table and the actual config surface cannot drift.

renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; html.lang?: string (可选); html.title?: string (可选); inject.stylesheets?: (string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | boolean>; })[] (可选) — Stylesheets linked into the document head; each entry is an href or a link record with integrity/crossorigin/attrs.; inject.scripts?: (string | { src: string; type?: string; async?: boolean; defer?: boolean; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<str… (可选) — Scripts emitted into the document; each entry is a src or a script record with type/async/defer/integrity/crossorigin/attrs.; inject.headFragments?: string[] (可选) — @dangerous fragments injected as-is. Trust boundary (same level as `trustedHtml`): never concatenate user-controlled content into these fragments; sanitize untrusted data at your own system boundary first. The framework only enforces no-`<script>` and no-executable-`<style>`.; ssr.noExternal?: (string | RegExp)[] (可选); island.upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); build.outDir?: string (可选) — Output directory for the build artifacts. Defaults to `dist`.; build.manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; } (可选) — Advisory only: exceeded budgets print build-manifest warnings and never fail the build; enforce them in your own build-output test.; viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; middleware.cors?: boolean (可选) — Enable the built-in CORS middleware.; middleware.corsOrigin?: string | string[] (可选) — Static CORS allowlist data, serialized into the generated entry as JSON. Mutually exclusive with {@link FrameworkOptions.middleware.corsOriginModule }.; middleware.corsOriginModule?: string (可选) — Path to a module that default-exports `(origin: string) => string | undefined`. The generated entry imports the module — the callback is never serialized — so it may close over module scope and import dependencies. Resolved with the same idiom as `appShell.import` (e.g. './app/cors-origin.ts'). Mutually exclusive with `corsOrigin`.; middleware.requestId?: boolean (可选) — Emit and honor a per-request id header.; middleware.logger?: boolean (可选) — Log each request through the built-in logger.; middleware.securityHeaders?: boolean (可选) — Attach the built-in security response headers.; middleware.csp?: { policy?: string; nonce?: boolean; reportOnly?: boolean; } (可选) — Content-Security-Policy emission: the policy string, nonce generation, and report-only mode.; middleware.use?: string[] (可选) — Fetch middleware chain (#858), composed around the framework handler in onion order (`use[0]` outermost), outside all built-in middleware above. Each entry is a MODULE PATH (same resolution idiom as `appShell.import`, e.g. './app/middleware/auth.ts') whose default export is a {@link Middleware}; the generated entry emits `import * as __mw_N from '<path>'` and composes `__mw_N.default` in configur…

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

The hydration delivery hint a component or route carries.

tagName: string (必填); layer: ComponentLayer (必填); hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选)

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Idle-hydration scheduling fallback (milliseconds) when neither `requestIdleCallback` nor `requestAnimationFrame` is available.

One module import the generated entry emits.

from: string (必填); names: string[] (必填); alias?: string (可选)

The wire-validator face of the one canonical attribute-name predicate (delegates to `./forbidden-sinks.ts`); exported for parity tests.

The static-sidecar descriptor router injects into the element compiler.

One island the build admits: tag, module path, and delivery facts.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); exportName?: string (可选) — Optional named export to register as the custom element constructor. Set for package islands from the manifest declaration's `className` (the CEM-derived export class name), so the client island factory can read `mod[exportName]` after #638 removed `export default` from UI component chunks. Absent for local/route islands (which use default).; hydrate?: IslandDeliveryStrategy (可选); ssr?: boolean (可选); dsd?: boolean (可选); authoring?: "basic-element" | "third-party-wc" (可选); source?: "local" | "package" | "nested" (可选); reason?: string (可选)

Adapter-owned browser delivery strategy, including media-query admission.

Per-island delivery options (hydration strategy, SSR/DSD participation).

hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选) — Hydration strategy: - 'load': load immediately when module is imported - 'idle': defer to requestIdleCallback (default) - 'visible': use IntersectionObserver to defer until element is visible - 'only': client-only render, no DSD/SSR output Named `hydrate` to match `defineIslandConfig()` in the Router package — one option name across both packages.; dsd?: boolean (可选) — Whether to use DSD for SSR rendering of this island. Honored by the build-side island scan (via `defineIslandConfig`), not by `defineIsland()` itself: passing it in `IslandOptions` has no runtime effect.; ssr?: boolean (可选) — Whether this island may be admitted into server rendering. Like `dsd`, decided by the build-side island scan; inert when passed to `defineIsland()`.

Options for the build-time island source transform.

islandsDir: string (必填) — Directory containing island files (e.g. "app/islands"); filePath: string (必填) — Absolute or relative file path of the source being processed

The island transform output: rewritten source plus extracted facts.

code: string (必填) — Transformed source code with markers; islands: { tagName: string; filePath: string; }[] (必填) — Detected island entries; map?: string (可选) — Optional source map

The one safe-attribute-name predicate (#1033, #602). Attribute *names* are not escaped on any render path, so a name must be valid HTML attribute-name grammar (blocks quote/space injection), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/ `srcdoc` — case-insensitive). Every boundary that admits an attribute name — the compiler semantic core, the Part Program validator, the compiled server validator, and the SSR head/meta name checks — delegates here, so the rules cannot diverge per path.

An event binding scoped to each item of an `each` region. The runtime attaches this listener to every item root node created by the region, making per-item handlers (onClick={this.select(row.id)}) expressible without fixed-path event parts.

event: string (必填) — DOM event name ('click', 'input', …).; handler: string (必填) — Handler method name on the compiled class.; action: ProgramEventAction (必填) — The action to dispatch, same union as fixed event parts.; selector?: string (可选) — Optional child selector within the item template (e.g. '.probe-button'). When omitted, the listener attaches to the item root.

Element-lifecycle failures: the kernel was driven outside its contract (phase `csr`).

Route loader: fetches data for a page route.

Context passed to a request-time ('dynamic') route loader.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Locale-aware resolved path contract.

locale: string (必填); path: string (必填); localizedPath: string (必填); isDefaultLocalePath: boolean (必填)

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Nested element expansion depth bound for `renderDsd`: cyclic component composition fails closed instead of recursing without end.

Fetch middleware contract (#858): WinterCG shape, dialect-free — no Hono/h3 context object. Composed at the handler boundary in onion order (`use[0]` is outermost: it sees the request first and the response last), so it runs with identical semantics in the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry. A middleware may short-circuit by returning a Response without calling `next()`, or post-process the Response that `next()` returns. Module contract: a Middleware is the DEFAULT EXPORT of a module referenced from `middleware.use` by path (e.g. './app/middleware/auth.ts'). The generated server entry imports the module, so the middleware may close over module scope and import local helpers and third-party packages — it is a real module in the server module graph, never serialized source.

One middleware module the generated entry composes.

kind: "requestId" | "logger" | "cors" | "securityHeaders" | "csp" (必填); comment?: string (可选); config.corsOrigin?: CorsOriginConfig (可选); config.corsOriginModule?: string (可选) — Normalized import path of a module default-exporting `(origin: string) => string | undefined`. The generated entry imports the module and passes its default export to `cors({ origin })` — the callback is referenced, never serialized.; config.warnOnDefaultCors?: boolean (可选) — #1411: emit the default-CORS production advisory. Absent means "warn" (production builds); the dev server sets false so the first run is warning-free.; config.csp?: CspConfig (可选)

The scope one middleware applies to (all routes or a named route set).

varName: string (必填); scope: string (必填); importPath: string (必填)

One documented attribute of a custom element declaration.

name: string (必填); type?: string (可选); default?: string (可选); description?: string (可选); reflects?: boolean (可选); fieldName?: string (可选)

Blog options stored in the build context by

contentDir?: string (可选); basePath?: string (可选)

Minimal build context interface that sub-plugins can use.

plugins: { [key: string]: unknown; blogOptions: OpenElementBlogOptions | null; navSections: OpenElementNavSection[]; headerNav: OpenElementHeaderNavLink[]; sitemapOptio… (必填); registerPlugin: (name: string, instance: unknown) => void (必填) — Register plugin data by name. Protocol level uses loose typing; concrete implementations should tighten the generic constraint.

One documented CSS part of a custom element declaration.

name: string (必填); description?: string (可选)

One custom element declaration in a package manifest: tag, members and delivery metadata.

tagName: string (必填); className?: string (可选); superclassName?: string (可选); attributes?: OpenElementAttribute[] (可选); events?: OpenElementEvent[] (可选); slots?: OpenElementSlot[] (可选); cssParts?: OpenElementCssPart[] (可选); openElement.ssr?: boolean (可选); openElement.dsd?: boolean (可选); openElement.layer?: ComponentLayer (可选); openElement.hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); openElement.status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; openElement.module?: string (可选); openElement.export?: string (可选); description?: string (可选)

Framework error carrying a stable code, severity, phase and recoverability contract.

Constructor options for {@linkcode OpenElementError}; every field is defaulted.

cause?: Error (可选); code?: string (可选); statusCode.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; statusCode.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; statusCode.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; statusCode.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; statusCode.valueOf: () => number (必填) — Returns the primitive value of the specified object.; statusCode.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; severity?: ErrorSeverity (可选); phase?: ErrorPhase (可选); recoverable?: boolean (可选)

One documented custom event of a custom element declaration.

name: string (必填); type?: string (可选); description?: string (可选)

The openElement-specific extension block of a package manifest declaration.

ssr?: boolean (可选); dsd?: boolean (可选); layer?: ComponentLayer (可选); hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; module?: string (可选); export?: string (可选)

Header navigation link.

href: string (必填); label: string (必填)

i18n options stored in the build context by

Navigation section from

section: string (必填); items: { path: string; label: string; order?: number; }[] (必填)

Package manifest of component declarations (not a Custom Elements Manifest).

schemaVersion: string (必填); packageName: string (必填); version: string (必填); description?: string (可选); author?: string (可选); license?: string (可选); homepage?: string (可选); repository?: string (可选); declarations: OpenElementDeclaration[] (必填)

The host-neutral request handler every runtime adapter and generated server entry exposes: a WinterCG `(request, context?) => Response` with no server engine dialect baked in.

Host-agnostic route and asset contracts shared by app and build drivers.

One node of the host-agnostic route tree: the matched URL `path` and route kind, the source and module paths the drivers resolve, the optional registered tag and param names, and the nested `children`.

kind: OpenElementRouteKind (必填); path: string (必填); filePath?: string (可选); importPath?: string (可选); tagName?: string (可选); paramNames?: string[] (可选); children?: OpenElementRouteNode[] (可选); meta?: Record<string, unknown> (可选)

One documented slot of a custom element declaration.

name: string (必填); description?: string (可选)

One page route declaration in the generated entry descriptor.

kind: "page" (必填); path: string (必填); varName: string (必填); filePath: string (必填); defaultTagName: string (必填); tagName: string (必填); importPath: string (必填); isDynamic?: boolean (可选); paramNames?: string[] (可选); streamManifest?: StreamRouteManifest (可选)

The Part Program IR version this package defines (currently v1).

The comment marker closing a part anchor in serialized program markup.

toString: (radix?: number) => string (必填) — Returns a string representation of an object.; toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; valueOf: () => number (必填) — Returns the primitive value of the specified object.; toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

Anchor marker payloads shared by seed runtime consumers.

toString: (radix?: number) => string (必填) — Returns a string representation of an object.; toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; valueOf: () => number (必填) — Returns the primitive value of the specified object.; toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

The serializable Part Program v1: one compiled component as data.

version: 1 (必填); tag: string (必填); root: ProgramRoot (必填); template: ProgramTreeNode[] (必填); parts: ProgramPart[] (必填); regions: ProgramRegionRecord[] (必填); dependencies: ProgramDependencyRecord[] (必填); locations: ProgramLocationRecord[] (必填); sourceMap: ProgramSourceMap (必填) — Compile-time provenance. The canonical in-memory artifact always carries it; the serialized module payload omits it (no runtime consumer reads it), so the validator accepts programs with or without it but still verifies it strictly when present.; metadata: CompiledElementMetadata (必填)

The one deterministic program consumed by all execution modes.

version: 1 (必填); tag: string (必填); root: ProgramRoot (必填); template: ProgramTreeNode[] (必填); parts: ProgramPart[] (必填); regions: ProgramRegionRecord[] (必填); dependencies: ProgramDependencyRecord[] (必填); locations: ProgramLocationRecord[] (必填); sourceMap: ProgramSourceMap (必填) — Compile-time provenance. The canonical in-memory artifact always carries it; the serialized module payload omits it (no runtime consumer reads it), so the validator accepts programs with or without it but still verifies it strictly when present.; metadata: CompiledElementMetadata (必填)

Media type of the RFC 9457 action error channel (#863).

RFC 9457 Problem Details document (#863): the action error channel answers `application/problem+json` instead of the bespoke `{ type: 'error', error: { message } }` JSON, so HTTP tooling recognizes failures natively. With `type: 'about:blank'`, `title` is the HTTP reason phrase and `detail` carries the specific explanation. The wire shape is alpha-unfrozen; the 1.0 acceptance freezes it in this problem+json form.

type: string (必填) — URI reference identifying the problem type; 'about:blank' when none applies.; title: string (必填) — Short human-readable summary (the HTTP reason phrase for 'about:blank').; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; detail?: string (可选) — Human-readable explanation specific to this occurrence.

String attribute sink bound to a Signal.

k: "attr" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Boolean attribute sink bound to a Signal.

k: "bool" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Specialized fixed sinks make ownership explicit for class and style text.

k: "class" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

One condition clause of a when part.

signal: string (必填); op: ConditionOperator (必填); value: string | number | boolean (必填)

One module dependency the compiled module graph records.

signal: string (必填); owner: { kind: "part" | "region"; index: number; } (必填); location: string (必填)

A list part: repeats its template node per item of a bound signal.

k: "each" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); key: string (必填); field?: string (可选) — Restatement of the item field for single-field templates; omitted when the item template binds multiple fields (each `ival`/`iattrs` slot then carries its own field).; item: ProgramTreeNode[] (必填); itemEvents?: ItemEventBinding[] (可选) — Per-item event bindings (#1556 IR v2): listeners attached to each item.; location: ProgramLocation (必填)

A static element node of the program tree.

k: "el" (必填); id: string (必填); tag: string (必填); attrs: [string, string][] (必填); iattrs?: [string, string][] (可选) — Per-item attribute slots ([name, itemField]) — valid only inside an `each` item template. At mount/claim time the value resolves from the current item: `true` emits a bare attribute, `false`/`null`/`undefined` omit it, anything else serializes with String().; children: ProgramTreeNode[] (必填)

Program-shape failures: a Part Program (or one of its records) is malformed, or carries a value the wire format cannot express. Phase `validation`: these reject data before any DOM work starts.

The action one event part dispatches.

An event binding part: listener wiring between DOM event and action.

k: "event" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; event: string (必填); handler: string (必填); action: ProgramEventAction (必填); path: number[] (必填); location: ProgramLocation (必填)

Trusted-HTML content sink (alpha.9). The signal value must carry the runtime TrustedHtml capability; its HTML replaces the target element's content. The target's subtree is opaque to the claim path. The compiler emits this only for an explicit `innerHTML={this.<field>}` sink on an otherwise childless element — there is no implicit or discovery path to raw HTML.

k: "html" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Item-value text slot; valid only inside an `each` item template. `field` names the item field rendered by this slot — multi-field item templates carry one slot per field, and the compiler always emits it.

k: "ival" (必填); field: string (必填)

Exact compiler-owned location for one dynamic sink or range anchor.

id: string (必填); kind: "anchor" | "sink" (必填); path: number[] (必填); node?: string (可选)

A location record also makes the identity auditable without inspecting parts.

The discriminated union of dynamic parts a program instantiates.

The anchor node marking where a part binds in the tree.

k: "part" (必填); id: string (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

Where a part sits relative to its anchor.

offset.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; offset.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; offset.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; offset.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; offset.valueOf: () => number (必填) — Returns the primitive value of the specified object.; offset.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; line: number (必填); column: number (必填)

DOM property sink bound to a Signal; `path` is retained for seed consumers.

k: "prop" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

A named ref slot is serializable; the generated class supplies the ref value.

k: "ref" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; ref: string (必填); path: number[] (必填); location: ProgramLocation (必填)

One region the program tracks: the boundaries of a dynamic subtree.

id: string (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; kind: "when" | "each" (必填); anchor: string (必填); end: string (必填); source: string (必填)

The root of one program tree: element, part anchor, or text.

id: "root" (必填); kind: RootMode (必填); nodes: string[] (必填)

The kind of source record a program source map entry carries.

The program source map: authored spans projected onto emitted records.

version: 1 (必填); file: string (必填); records: ProgramSourceRecord[] (必填)

A half-open [start, end) range into the authored source text.

file: string (必填); start: ProgramPosition (必填); end: ProgramPosition (必填)

One source-map record: the authored origin of one emitted node or part.

id: string (必填); kind: ProgramSourceKind (必填); source: ProgramSourceRange (必填)

A style binding part.

k: "style" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

A static text node of the program tree.

k: "text" (必填); value: string (必填)

A text interpolation part bound to one signal.

k: "text" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); location: ProgramLocation (必填)

The discriminated union of static tree nodes.

A conditional part: swaps template branches on a condition.

k: "when" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); test: ProgramCondition (必填); on: ProgramTreeNode[] (必填); off: ProgramTreeNode[] (必填); location: ProgramLocation (必填)

The serialized value-type tag of a compiled property default.

Raise one framework failure and never return: the throwing companion of {@linkcode frameworkError}. The per-module `fail(code, message)` micro-factories bind their failure surface's fixed {@linkcode ErrorPhase} here — one implementation, the phase as a parameter — so a code and a phase cannot drift apart per throw site.

Elements whose text content must never be interpolated as markup.

Read-only signal protocol used by computed values.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@849.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

One page renderer module registration.

varName: string (必填); scope: string (必填); importPath: string (必填); depth.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; depth.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; depth.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; depth.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; depth.valueOf: () => number (必填) — Returns the primitive value of the specified object.; depth.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

One render failure record the SSR pipeline reports.

code: string (必填); severity: "error" | "warning" (必填); phase: string (必填); tagName: string (必填); message: string (必填); recoverable: boolean (必填)

The public result of one `renderDsd()` call: the serialized DSD `html`, the render errors collected while composing it (empty on success), the render metrics for the root component, and the hydration hints the client scheduler reads to upgrade islands.

html: string (必填); errors: RenderError[] (必填); metrics: DsdRenderMetrics (必填); hydrationHints: HydrationHint[] (必填)

The resolved shell for one plan slot: disabled (false) or a full declaration.

How the compiled component attaches its root: light DOM or a shadow root.

One route admitted by the scanner: URL `path`, source `filePath`, the route `type`, the generated variable name (`varName`) the entry binds it to, and the optional registration tag. {@link RouteEntry.definePage} and {@link RouteEntry.hasEnhancedForms} carry the two source-derived admission facts the generated entries branch on.

path: string (必填); filePath: string (必填); type: "page" | "api" | "island" | "special" (必填); varName: string (必填); tagName?: string (可选); definePage?: boolean (可选) — True when the route module's default export is a definePage() definition (#960 — registration decoupling). The generated entry registers the page class under the path-derived fallback tag and IGNORES the tagName export for registration: on a definePage route the export only names a content element. Plain element routes keep tagName as their registration tag.; source?: string (可选) — Source text captured during scanning when includeSource is enabled.; hasEnhancedForms?: boolean (可选) — True when the page route source carries data-open-enhance (#569): the client entry must ship the form-enhancement layer even when the app has zero islands.; special?: SpecialFileType (可选); params?: string[] (可选)

A single route metadata entry emitted as `routeInfo` by the generated SSG entry module (see entry-render-ssg.ts).

path: string (必填); filePath?: string (可选) — Route module file path. Read by the render pipeline: ssg-render.ts copies it into server-manifest.json for request-time (renderIntent 'dynamic') routes.; tagName: string (必填); module?: unknown (可选) — The route module namespace object (typed per-module at codegen time).; isDynamic: boolean (必填); paramNames: string[] (必填); rendering?: string (可选) — Rendering mode declared via renderIntent.mode ("static" when unset; the "auto" alias is rejected, #609).; hasAction?: boolean (可选) — True when the route module exports an action (request-time form POST).; streamManifest?: StreamRouteManifest (可选); params?: Record<string, string> (可选)

The module vocabulary router injects into `analyzeModuleSemantics`.

Whether the authored error prose is kept: `true` everywhere except a production client build, the one context that defines `OE_RUNTIME_MESSAGES` to `false`. Stripping is a payload decision, so it belongs to the browser bundle only — server-side failures keep their prose.

A host runtime adapter: exposes the fetch handler a server engine dispatches to.

name: string (必填); fetch: OpenElementRequestHandler<Env> (必填); prerender?: (() => AsyncIterable<RuntimePrerenderResult> | Iterable<RuntimePrerenderResult>) (可选)

Options one runtime adapter is constructed with.

name: string (必填); fetch: OpenElementRequestHandler<Env> (必填); prerender?: (() => AsyncIterable<RuntimePrerenderResult> | Iterable<RuntimePrerenderResult>) (可选)

runtime.ts - Runtime adapter protocol. Replacement boundary for Nitro, Workers, Node, Deno, or future fetch-compatible runtimes. Preserves openElement semantics while leaving concrete server engines outside this package.

env?: Env (可选); platform?: unknown (可选); params?: Record<string, string> (可选)

Runtime execution failures raised while a compiled program is serialized, built into fresh DOM, or re-read on a signal write (phase `render`).

Branded type: a string that has been HTML-escaped (safe for text content)

The JSON-serializable value shape a compiled property default admits.

Serialize the manifest as the generated dist/server/client-assets.js module: pure structured data, no injection logic — consumers derive what they need from these values.

entry: string (必填) — The island client entry URL ('' when no client bundle shipped).; islands: Record<string, ClientIslandAsset> (必填) — Compile-time island identity (delivery tag) -> emitted asset.; shared: string[] (必填) — Shared chunk URLs emitted by the client build (JS, neither entry nor island-dedicated).; styles: string[] (必填) — Preloadable island style asset URLs, sorted, base-prefixed. Shadow-component CSS cannot be applied as a document-level stylesheet — it cannot reach shadow trees — so the document channel's only role for these URLs is preload; the sheets themselves are adopted through the sheet adapters.

Compiled server/claim validation failures. The value shipped in 1.0.0-alpha.3 and is kept verbatim; `CompiledProgramValidationError` is its only raiser.

Canonical request-time/SSG server route context.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Context passed to a request-time ('dynamic') route loader. This is the server contract: the loader runs on the server with the Web-standard request, matched route params, the host environment and the platform object, and signals validation failure via fail()/redirect().

path: string (必填); filePath: string (必填)

Alias for APIs that accept either writable or read-only signals.

Runtime/type brand for signals created by the configured reactive engine.

Signal engine protocol used by the framework's built-in adapter. This is a deliberate internal seam, not a public compatibility contract: the framework layer talks to signals only through this narrow interface so its call sites stay implementation-agnostic. The package ships and verifies exactly one engine implementation (`preact-engine`, backed by `@preact/signals-core`). Preact's own API is not Element public API, and arbitrary third-party engines are not promised; any future engine would be added behind this protocol rather than inline (charter decision — see #723).

signal: <T>(initialValue: T) => WritableSignal<T> (必填); computed: <T>(fn: () => T) => ReadonlySignal<T> (必填); effect: (fn: () => void | Unsubscribe) => Unsubscribe (必填)

Minimal signal-like object accepted by renderers and bindings.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@849.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Special file kinds the route scanner recognizes by filename: `renderer` and `middleware`.

Speculation Rules configuration for SSG post-processing

prerender?: string[] (可选) — URL patterns to prerender (fully render in background before navigation).; prefetch?: string[] (可选) — URL patterns to prefetch (fetch HTML + resources without rendering).; exclude?: string[] (可选) — URL patterns to exclude from both prefetch and prerender.; eagerness?: "immediate" | "moderate" | "conservative" (可选) — Eagerness level for prerender rules.

User-facing SSG build behavior switches (OpenElementOptions['ssg']).

dynamicRouteFailure?: "fail" | "warn" (可选) — Policy for dynamic-route render failures during SSG. See {@link SsgRenderOptions.dynamicRouteFailure}.

Per-page render diagnostics returned by renderRoute()

html: string (必填) — Rendered HTML string; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; redirect?: { location: string; status: number; } (可选) — Redirect outcome (3xx). When set, `html` holds an interim status page and the result must not be persisted as a normal 200 page.; notFound?: boolean (可选) — True when the route signalled not-found (404).; errors: RenderError[] (必填) — Render errors collected during rendering; componentCount: number (必填) — Number of DSD components rendered on this page; renderTimeMs: number (必填) — Total render time for all components on this page (ms)

The per-build render evidence record the SSG engine emits for audit.

i18nOptions?: { [key: string]: unknown; locales: string[]; defaultLocale?: string; } | null (可选); admissionDecisions?: SsrAdmissionDecision[] (可选) — SSR admission decisions from the plan that rendered the pages.; manifestBudget.islandKB?: number (可选); manifestBudget.totalJsKB?: number (可选); manifestBudget.pageKB?: number (可选); onPrintBuildManifest?: ((input: { root: string; outDir: string; phase: 3; headExtras?: string; budget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; }; }) => void | Prom… (可选)

Options passed to the shared SSG render pipeline.

root: string (必填); outDir: string (必填); base?: string (可选); headExtras?: string (可选); html.lang?: string (可选); html.title?: string (可选); middleware.csp?: { policy?: string; reportOnly?: boolean; nonce?: boolean; } (可选); upgradeStrategy?: string (可选); viewTransition?: boolean (可选); speculation?: boolean | Record<string, unknown> (可选); islandTagNames?: string[] (可选); routesDir?: string (可选); dynamicRouteFailure?: "fail" | "warn" (可选) — Policy for dynamic-route render failures (HTTP status >= 500, non-empty render errors, or a renderRoute throw) during SSG. - 'fail' (default): abort the build - a failed page must never ship as a normal 200 page. - 'warn': log the failure and skip the page (the page is not written and is not registered in the ISR manifest).

Summary of an SSG render run, returned by ssgRender().

staticNon200: { path: string; status: number; }[] (必填) — Static routes whose handler returned a non-200 status. hono/ssg drops these responses (defaultPlugin), so they are not written to disk; they are listed here and in the build log instead of disappearing silently.; warnings: string[] (必填) — Non-fatal warnings collected during the SSG run (sitemap generation failures, etc.). Surfaced here so the build summary / release evidence carries them instead of letting them disappear silently.

Property on the SSR registry holding the TRUE original `define` method, captured before the generated entry installs its idempotent wrapper. The registry outlives vite dev SSR module re-evaluations, so without this the second evaluation would capture the already-wrapped `define` as its "original" and every forced re-registration would silently early-return through the previous wrapper (#1339 lit dev feedback).

Marker property set to `true` on the SSR customElements stub. Readers must treat the marked registry as re-definable.

The build's admission verdict for one discovered tag: where the declaration lives (`modulePath`), how it was discovered (`source`), which render path it is admitted to, and the reason recorded for the manifest.

tagName: string (必填); modulePath: string (必填) — Module path of the island declaration. Empty for 'foreign' decisions: a foreign tag is consumed in JSX but declares no module the build owns.; source: "local" | "package" | "nested" | "foreign" (必填) — 'foreign' (#979): a third-party WC tag discovered by the foreign-tag scanner in page/island JSX — recorded for visibility only; SSR still treats it as an opaque passthrough (renderPath 'client-only').; renderPath: "client-only" | "rejected" | "ssr+client" (必填); reason: string (必填)

The build-time SSR admission decisions per component tag.

renderableTags: string[] (必填); clientOnlyTags: string[] (必填); rejectedTags: string[] (必填); reasons: Record<string, string> (必填); decisions: SsrAdmissionDecision[] (必填); cemClassifications?: CompatibilityClassification[] (可选); foreignTags?: string[] (可选) — #979: foreign custom-element tags discovered in page / island JSX that are neither local islands, package-manifest islands, nor openElement-authored elements. Visibility only — each tag also carries a source:'foreign' decision (renderPath 'client-only') and the SSR/behavior is unchanged (opaque passthrough).

The server bundle facts the SSG engine consumes for stream rendering.

The one `<style>` element the server serializer emits as the first DSD template child when the class carries static styles (renderDsd parity — pages never upgrade, so their styles must ship in the payload). The claim path skips exactly this marked node; a marked node on a style-less class is claim drift and fails closed.

Build-host-only compiled component reached through a route's local import graph. These components participate in recursive SSR/SSG expansion but are not client islands and therefore add no hydration or browser entry.

tagName: string (必填); modulePath: string (必填); compilerInteractionEvents: string[] (必填) — Compiler-owned interaction events; empty means no inferred browser entry.

Where an island's resolved hydration strategy came from.

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Build-only route projection bound to a specific compiled page program.

program: { version: number; tag: string; sha256: string; } (必填); fields: { field: string; signal: string; owners: Array<{ kind: "part" | "region"; index: number; location: string; source: PartProgramV1["sourceMap"]["records"][number… (必填)

Compiled-style application failures (phase `csr`).

Minimal stylesheet contract (replaceSync + cssRules) satisfied by native and shim sheets.

replaceSync: (text: string) => void (必填); cssRules: StyleSheetRule[] (必填)

Cross-environment CSSStyleSheet abstraction. In browsers this delegates to the native CSSStyleSheet API. In SSR runtimes it falls back to a minimal in-memory implementation that exposes the subset used by OpenElement and renderDsd().

cssText: string (必填)

Branded type: a string that is intentionally raw/untrusted HTML

Whether a static attribute (name/value as authored into the Part Program) makes a streamed frame unsafely installable: event-handler, seed-spoofing, and srcdoc names fail outright, and URL-carrying names fail when the entity-decoded, control-stripped value carries a script scheme.

Unsubscribe function returned by subscriptions and effects.

Validate an unknown value as a Part Program v1. The validator is intentionally strict: unknown instruction kinds, missing ownership records and unsafe paths fail before a runtime can guess at their meaning.

HTML void elements — the ONE canonical tag set for every serializer, validator, and compiler in the workspace (issue #1220, M4). This module is import-free and host-free by design: it sits at the base of the module graph so the DOM runtime (internal/core/html-escape.ts), the Part Program exchange artifact (internal/protocol/part-program.ts), and the compiler semantic core can all consume the same definition without an import cycle or a second source of truth. Content is the full HTML Standard void-element list, `param` included. Do not redefine this set anywhere else; internal/core/html-escape.ts and internal/protocol/part-program.ts re-export it, and __tests__/void-tags-convergence.test.ts enforces the single owner.

Writable signal protocol used by openElement integrations.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@849.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Host-agnostic route and asset contracts shared by app and build drivers.

One node of the host-agnostic route tree: the matched URL `path` and route kind, the source and module paths the drivers resolve, the optional registered tag and param names, and the nested `children`.

kind: OpenElementRouteKind (必填); path: string (必填); filePath?: string (可选); importPath?: string (可选); tagName?: string (可选); paramNames?: string[] (可选); children?: OpenElementRouteNode[] (可选); meta?: Record<string, unknown> (可选)

The Phase 2 client build's delivery manifest, keyed by island identity.

entry: string (必填) — The island client entry URL ('' when no client bundle shipped).; islands: Record<string, ClientIslandAsset> (必填) — Compile-time island identity (delivery tag) -> emitted asset.; shared: string[] (必填) — Shared chunk URLs emitted by the client build (JS, neither entry nor island-dedicated).; styles: string[] (必填) — Preloadable island style asset URLs, sorted, base-prefixed. Shadow-component CSS cannot be applied as a document-level stylesheet — it cannot reach shadow trees — so the document channel's only role for these URLs is preload; the sheets themselves are adopted through the sheet adapters.

The client asset one compile-time island identity resolves to.

file: string (必填) — Emitted asset URL (site-root relative, base-prefixed) of the chunk that carries the island module — its dedicated chunk, a shared chunk, or the client entry when the island has no chunk of its own.; strategy: IslandDeliveryStrategy (必填) — Delivery strategy resolved from the island declaration at build time.; preload?: boolean (可选) — True when the island's delivery strategy hydrates at load time, so the asset is a modulepreload candidate.

The manifest a project without a client bundle carries.

Serialize the manifest as the generated dist/server/client-assets.js module: pure structured data, no injection logic — consumers derive what they need from these values.

entry: string (必填) — The island client entry URL ('' when no client bundle shipped).; islands: Record<string, ClientIslandAsset> (必填) — Compile-time island identity (delivery tag) -> emitted asset.; shared: string[] (必填) — Shared chunk URLs emitted by the client build (JS, neither entry nor island-dedicated).; styles: string[] (必填) — Preloadable island style asset URLs, sorted, base-prefixed. Shadow-component CSS cannot be applied as a document-level stylesheet — it cannot reach shadow trees — so the document channel's only role for these URLs is preload; the sheets themselves are adopted through the sheet adapters.

Route action: handles form submissions for a page route.

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Context passed to a route action function (extends loader context).

formData: FormData (必填); request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Wire shape returned to the JavaScript form-enhancement path. The no-JS path never sees this: it gets the equivalent semantics as plain HTTP (303 on success, 422 with the re-rendered form on validation failure, redirect/error as status codes). Success carries no data envelope. The application-loop contract makes a successful non-GET action answer 303 (PRG) — the framework never answers 200 with a rendered page, or with a success document, for a successful mutation — so the fetch channel answers `{ type: 'redirect' }` naming the PRG target and the authored return value is discarded by design. Success data travels the PRG target instead (query state the loader re-runs with, which the props projector then maps; see the router guide's "Form actions" section). The union previously declared a `{ type: 'success' }` member that no code path ever emitted — removed so the type matches the wire. Error outcomes (CSRF 403, unknown action 404, unparseable body 400, unexpected 500) are NOT part of this union: since #863 they answer RFC 9457 Problem Details with the PROBLEM_JSON_MEDIA_TYPE content type — see ProblemDetails.

Route loader: fetches data for a page route.

Context passed to a request-time ('dynamic') route loader.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Media type of the RFC 9457 action error channel (#863).

RFC 9457 Problem Details document (#863): the action error channel answers `application/problem+json` instead of the bespoke `{ type: 'error', error: { message } }` JSON, so HTTP tooling recognizes failures natively. With `type: 'about:blank'`, `title` is the HTTP reason phrase and `detail` carries the specific explanation. The wire shape is alpha-unfrozen; the 1.0 acceptance freezes it in this problem+json form.

type: string (必填) — URI reference identifying the problem type; 'about:blank' when none applies.; title: string (必填) — Short human-readable summary (the HTTP reason phrase for 'about:blank').; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; detail?: string (可选) — Human-readable explanation specific to this occurrence.

Canonical request-time/SSG server route context.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Context passed to a request-time ('dynamic') route loader. This is the server contract: the loader runs on the server with the Web-standard request, matched route params, the host environment and the platform object, and signals validation failure via fail()/redirect().

path: string (必填); filePath: string (必填)

Attribute/authoring-surface failures (phase `validation`).

Claim failures: the existing DOM does not match the program that would own it. The value shipped in 1.0.0-alpha.3 and is kept verbatim; consumers match on it, and `PartProgramClaimError` is its only raiser.

Compiler (build-time) failures. The per-diagnostic `OEC####` codes stay on each diagnostic; these classify the family so a build failure is catchable as one thing.

Community-context service lifecycle failures (phase `csr`).

Default code for {@linkcode RenderError }. Deliberately NOT a member of {@linkcode ErrorCode}: that object is the scan target of the documentation site's error catalog, which requires every member to carry a phase/severity family rule. `RENDER_ERROR` is the pre-dialect value `RenderError` has always defaulted to — kept verbatim so callers that observe it keep working, and kept out of the catalogue because it is not a failure this package classifies, only a constructor default a caller may override.

Keyed-list identity failures. Shared by the server serializer and the client runtime (see `internal/compiled/each-key.ts`), so both executors reject the same data with the same code.

Error message prefix for all openElement errors.

Well-known error code constants for reference. String values are always accepted.

The pipeline phase an error was raised in.

How severe a framework error is.

Callback receiving every reported {@linkcode OpenElementError} for telemetry.

SSR/bootstrap failures raised by the public entries (phase `ssr` / `csr`).

One framework failure: {@linkcode OpenElementError} with the caller's code and the phase/severity/recoverability that phase implies. Every throw site in this package goes through this factory (or the `*ErrorCode` tables above) so a code, a phase and a recoverability answer cannot drift per site.

Element-lifecycle failures: the kernel was driven outside its contract (phase `csr`).

Framework error carrying a stable code, severity, phase and recoverability contract.

Constructor options for {@linkcode OpenElementError}; every field is defaulted.

cause?: Error (可选); code?: string (可选); statusCode.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; statusCode.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; statusCode.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; statusCode.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; statusCode.valueOf: () => number (必填) — Returns the primitive value of the specified object.; statusCode.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; severity?: ErrorSeverity (可选); phase?: ErrorPhase (可选); recoverable?: boolean (可选)

Program-shape failures: a Part Program (or one of its records) is malformed, or carries a value the wire format cannot express. Phase `validation`: these reject data before any DOM work starts.

Raise one framework failure and never return: the throwing companion of {@linkcode frameworkError}. The per-module `fail(code, message)` micro-factories bind their failure surface's fixed {@linkcode ErrorPhase} here — one implementation, the phase as a parameter — so a code and a phase cannot drift apart per throw site.

Whether the authored error prose is kept: `true` everywhere except a production client build, the one context that defines `OE_RUNTIME_MESSAGES` to `false`. Stripping is a payload decision, so it belongs to the browser bundle only — server-side failures keep their prose.

Runtime execution failures raised while a compiled program is serialized, built into fresh DOM, or re-read on a signal write (phase `render`).

Compiled server/claim validation failures. The value shipped in 1.0.0-alpha.3 and is kept verbatim; `CompiledProgramValidationError` is its only raiser.

Compiled-style application failures (phase `csr`).

The one camelCase → kebab-case casing rule for custom-element attribute names, so `<x-el itemCount={5}>` round-trips as `item-count` on every boundary that derives an attribute name from a prop name: the compiler's property metadata, the SSR serializer, and the client attribute handling.

Forbidden sink names — the ONE canonical deny list for every Part Program boundary: the compiler semantic core, the protocol validator (internal/protocol/part-program.ts), and the compiled server/claim validator (internal/compiled/server/shared.ts). This module is import-free and host-free by design (same base-of-graph contract as void-tags.ts): all consumers import it, so a new forbidden sink cannot be enforced on one boundary and missed on another. This module owns the named-sink deny lists and the attribute-name policy built on them (the one shared safe-attribute-name predicate and the one camelCase→kebab-case casing rule); consumers delegate so the boundary cannot diverge. The lists are fail closed and case-insensitive (attribute and property names are compared lowercase, matching the HTML parser's name folding): - `FORBIDDEN_ATTRIBUTE_NAMES`: attribute names that must never be a static attribute or an `attr`/`bool` sink. `srcdoc` smuggles a full HTML document past attribute escaping; `innerHTML` is admissible only through the dedicated trusted-HTML `html` Part, never as a plain attribute name. - `FORBIDDEN_PROPERTY_NAMES`: `prop` sink names that would re-prototype or re-construct the target element (prototype-pollution primitives). - `RAW_TEXT_TAGS`: raw-text elements are outside the compiled grammar — their content cannot be escaped by the serializer.

Property names the compiler refuses as

Sink categories the canonical deny list classifies.

Return a human-readable reason when `name` is a forbidden sink of `kind`, or null when the name is admissible. Unknown kinds fail closed with a reason instead of being waved through.

The one safe-attribute-name predicate (#1033, #602). Attribute *names* are not escaped on any render path, so a name must be valid HTML attribute-name grammar (blocks quote/space injection), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/ `srcdoc` — case-insensitive). Every boundary that admits an attribute name — the compiler semantic core, the Part Program validator, the compiled server validator, and the SSR head/meta name checks — delegates here, so the rules cannot diverge per path.

Elements whose text content must never be interpolated as markup.

Application shell declaration: `false` disables the shell entirely, `'default'` uses the built-in shell, and the object form names a tag with the module path that defines it (`import`, resolved like a {@link FrameworkOptions.middleware.use } entry) plus the compiled shell properties the router injects per route.

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

The delivery layer a component belongs to: fully static DSD markup ('dsd-static'), DSD markup with a client island ('dsd-interactive'), a client-only island with no SSR output ('pure-island'), or a light-DOM element ('light-dom'). Recorded per component in the build manifest and consumed by the hydration scheduler.

The adapter-facing framework options: where routes, islands and components live, which renderer serializes pages, the application shell and layout declarations, the document `<html>`/head injection channels, and the request-time middleware switches. Every field is optional; the adapter applies its documented default. This is the type an application config file's default export is checked against, so the rendered option table and the actual config surface cannot drift.

renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; html.lang?: string (可选); html.title?: string (可选); inject.stylesheets?: (string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | boolean>; })[] (可选) — Stylesheets linked into the document head; each entry is an href or a link record with integrity/crossorigin/attrs.; inject.scripts?: (string | { src: string; type?: string; async?: boolean; defer?: boolean; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<str… (可选) — Scripts emitted into the document; each entry is a src or a script record with type/async/defer/integrity/crossorigin/attrs.; inject.headFragments?: string[] (可选) — @dangerous fragments injected as-is. Trust boundary (same level as `trustedHtml`): never concatenate user-controlled content into these fragments; sanitize untrusted data at your own system boundary first. The framework only enforces no-`<script>` and no-executable-`<style>`.; ssr.noExternal?: (string | RegExp)[] (可选); island.upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); build.outDir?: string (可选) — Output directory for the build artifacts. Defaults to `dist`.; build.manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; } (可选) — Advisory only: exceeded budgets print build-manifest warnings and never fail the build; enforce them in your own build-output test.; viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; middleware.cors?: boolean (可选) — Enable the built-in CORS middleware.; middleware.corsOrigin?: string | string[] (可选) — Static CORS allowlist data, serialized into the generated entry as JSON. Mutually exclusive with {@link FrameworkOptions.middleware.corsOriginModule }.; middleware.corsOriginModule?: string (可选) — Path to a module that default-exports `(origin: string) => string | undefined`. The generated entry imports the module — the callback is never serialized — so it may close over module scope and import dependencies. Resolved with the same idiom as `appShell.import` (e.g. './app/cors-origin.ts'). Mutually exclusive with `corsOrigin`.; middleware.requestId?: boolean (可选) — Emit and honor a per-request id header.; middleware.logger?: boolean (可选) — Log each request through the built-in logger.; middleware.securityHeaders?: boolean (可选) — Attach the built-in security response headers.; middleware.csp?: { policy?: string; nonce?: boolean; reportOnly?: boolean; } (可选) — Content-Security-Policy emission: the policy string, nonce generation, and report-only mode.; middleware.use?: string[] (可选) — Fetch middleware chain (#858), composed around the framework handler in onion order (`use[0]` outermost), outside all built-in middleware above. Each entry is a MODULE PATH (same resolution idiom as `appShell.import`, e.g. './app/middleware/auth.ts') whose default export is a {@link Middleware}; the generated entry emits `import * as __mw_N from '<path>'` and composes `__mw_N.default` in configur…

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Locale-aware resolved path contract.

locale: string (必填); path: string (必填); localizedPath: string (必填); isDefaultLocalePath: boolean (必填)

Fetch middleware contract (#858): WinterCG shape, dialect-free — no Hono/h3 context object. Composed at the handler boundary in onion order (`use[0]` is outermost: it sees the request first and the response last), so it runs with identical semantics in the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry. A middleware may short-circuit by returning a Response without calling `next()`, or post-process the Response that `next()` returns. Module contract: a Middleware is the DEFAULT EXPORT of a module referenced from `middleware.use` by path (e.g. './app/middleware/auth.ts'). The generated server entry imports the module, so the middleware may close over module scope and import local helpers and third-party packages — it is a real module in the server module graph, never serialized source.

Blog options stored in the build context by

contentDir?: string (可选); basePath?: string (可选)

Minimal build context interface that sub-plugins can use.

plugins: { [key: string]: unknown; blogOptions: OpenElementBlogOptions | null; navSections: OpenElementNavSection[]; headerNav: OpenElementHeaderNavLink[]; sitemapOptio… (必填); registerPlugin: (name: string, instance: unknown) => void (必填) — Register plugin data by name. Protocol level uses loose typing; concrete implementations should tighten the generic constraint.

Header navigation link.

href: string (必填); label: string (必填)

i18n options stored in the build context by

Navigation section from

section: string (必填); items: { path: string; label: string; order?: number; }[] (必填)

One route admitted by the scanner: URL `path`, source `filePath`, the route `type`, the generated variable name (`varName`) the entry binds it to, and the optional registration tag. {@link RouteEntry.definePage} and {@link RouteEntry.hasEnhancedForms} carry the two source-derived admission facts the generated entries branch on.

path: string (必填); filePath: string (必填); type: "page" | "api" | "island" | "special" (必填); varName: string (必填); tagName?: string (可选); definePage?: boolean (可选) — True when the route module's default export is a definePage() definition (#960 — registration decoupling). The generated entry registers the page class under the path-derived fallback tag and IGNORES the tagName export for registration: on a definePage route the export only names a content element. Plain element routes keep tagName as their registration tag.; source?: string (可选) — Source text captured during scanning when includeSource is enabled.; hasEnhancedForms?: boolean (可选) — True when the page route source carries data-open-enhance (#569): the client entry must ship the form-enhancement layer even when the app has zero islands.; special?: SpecialFileType (可选); params?: string[] (可选)

Branded type: a string that has been HTML-escaped (safe for text content)

Special file kinds the route scanner recognizes by filename: `renderer` and `middleware`.

Where an island's resolved hydration strategy came from.

Branded type: a string that is intentionally raw/untrusted HTML

Per-island delivery options (hydration strategy, SSR/DSD participation).

hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选) — Hydration strategy: - 'load': load immediately when module is imported - 'idle': defer to requestIdleCallback (default) - 'visible': use IntersectionObserver to defer until element is visible - 'only': client-only render, no DSD/SSR output Named `hydrate` to match `defineIslandConfig()` in the Router package — one option name across both packages.; dsd?: boolean (可选) — Whether to use DSD for SSR rendering of this island. Honored by the build-side island scan (via `defineIslandConfig`), not by `defineIsland()` itself: passing it in `IslandOptions` has no runtime effect.; ssr?: boolean (可选) — Whether this island may be admitted into server rendering. Like `dsd`, decided by the build-side island scan; inert when passed to `defineIsland()`.

Options for the build-time island source transform.

islandsDir: string (必填) — Directory containing island files (e.g. "app/islands"); filePath: string (必填) — Absolute or relative file path of the source being processed

The island transform output: rewritten source plus extracted facts.

code: string (必填) — Transformed source code with markers; islands: { tagName: string; filePath: string; }[] (必填) — Detected island entries; map?: string (可选) — Optional source map

The static-sidecar descriptor router injects into the element compiler.

The compatibility classification report for one custom element manifest.

totalClassified.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; totalClassified.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; totalClassified.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; totalClassified.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; totalClassified.valueOf: () => number (必填) — Returns the primitive value of the specified object.; totalClassified.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; ssrCapableCount: number (必填); clientOnlyCount: number (必填); rejectedCount: number (必填); experimentalDomCount: number (必填); classifications: CompatibilityClassification[] (必填); summary: string (必填)

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

One documented attribute of a custom element declaration.

name: string (必填); type?: string (可选); default?: string (可选); description?: string (可选); reflects?: boolean (可选); fieldName?: string (可选)

One documented CSS part of a custom element declaration.

name: string (必填); description?: string (可选)

One custom element declaration in a package manifest: tag, members and delivery metadata.

tagName: string (必填); className?: string (可选); superclassName?: string (可选); attributes?: OpenElementAttribute[] (可选); events?: OpenElementEvent[] (可选); slots?: OpenElementSlot[] (可选); cssParts?: OpenElementCssPart[] (可选); openElement.ssr?: boolean (可选); openElement.dsd?: boolean (可选); openElement.layer?: ComponentLayer (可选); openElement.hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); openElement.status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; openElement.module?: string (可选); openElement.export?: string (可选); description?: string (可选)

One documented custom event of a custom element declaration.

name: string (必填); type?: string (可选); description?: string (可选)

The openElement-specific extension block of a package manifest declaration.

ssr?: boolean (可选); dsd?: boolean (可选); layer?: ComponentLayer (可选); hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; module?: string (可选); export?: string (可选)

Package manifest of component declarations (not a Custom Elements Manifest).

schemaVersion: string (必填); packageName: string (必填); version: string (必填); description?: string (可选); author?: string (可选); license?: string (可选); homepage?: string (可选); repository?: string (可选); declarations: OpenElementDeclaration[] (必填)

One documented slot of a custom element declaration.

name: string (必填); description?: string (可选)

One module-scan vocabulary entry the host admits: a binding identity (module specifier + exported name, aliases followed) plus the fact a canonical call of that binding contributes. Plain data — the scan consumes the descriptors without learning the caller's package vocabulary, the same direction as the compiler's {@link StaticSidecarDescriptor} admission (#1473 item 3).

moduleSpecifier: string (必填) — Canonical module specifier the factory must be imported from.; exportName: string (必填) — Exported name of the factory binding.; kind: "page-definition" | "element-registration" (必填) — What a canonical call of the binding contributes to the scan.

One static-sidecar descriptor the host injects into the element compiler: the admission granted is a colocated static policy statement (#1473 item 3, the static-sidecar admission pattern).

moduleSpecifier: string (必填) — Canonical module specifier the sidecar export must be imported from.; exportName: string (必填) — Exported name of the sidecar factory binding.; kind: "static-sidecar" (必填) — The admission granted: a colocated static policy statement.

The module vocabulary router injects into `analyzeModuleSemantics`.

One property entry of the compiled custom-elements-manifest metadata.

name: string (必填); fieldName: string (必填); type: PropertyValueType (必填); attribute: string | null (必填); reflect: boolean (必填)

Version of the compiled-module ABI: the statics a generated module carries (`__partProgram`, `__compiledProperties`, `__elementMetadata`, `__observedAttributes`, `__computedFields`) and the runtime facade binds. Bump when the generated-module contract changes shape; generated artifacts stamp both this and PART_PROGRAM_VERSION so consumers can tell format drift from release drift. v2: platform lifecycle callback bodies are emitted inside a boundary-capture wrapper calling the base class's `_captureError` — a generated module now requires a runtime facade carrying that protected method (the v1 shape emitted the bodies verbatim).

The compiled custom-elements-manifest metadata block of one component.

tagName: string (必填); className: string (必填); declaration: { name: string; module: string; } (必填); attributes: { name: string; fieldName: string; type: PropertyValueType; reflect: boolean; }[] (必填); members: CemPropertyMetadata[] (必填)

The compiled element metadata the program carries for tooling consumers.

tag: string (必填); className: string (必填); sourceFile: string (必填); properties: CompiledPropertyMetadata[] (必填); observedAttributes: string[] (必填); cem: CompiledCemMetadata (必填)

One compiled

name: string (必填); attribute: string | null (必填); type: PropertyValueType (必填); converter: PropertyValueType (必填); reflect: boolean (必填); default: SerializableValue (必填); computed?: boolean (可选) — True for computed fields (`= computed(() => ...)` in the source): their signal is derived from other property signals by the generated `__computedFields` factory, never seeded from attributes/props. Always paired with `attribute: null` and `reflect: false`.; deps?: string[] (可选) — Source signal names a computed field reads (declaration order).

Operator/literal compatibility for when-Region tests (issue #1372). Both wire validators (this module and the server serializer's shared validator) close the space through this one predicate: - ordering operators require a finite numeric literal; - `equals`/`not-equals` admit a finite number, string, or boolean; - `truthy` admits exactly `true` or `false` (the recorded expectation).

The comparison operators a program condition supports.

Internal SSR provenance marker on light-mode host tags (#1148). Present only when the host's light subtree was server-rendered under the in-place activation contract: the client binds the existing DOM instead of clearing it, and a parent's activation walk prunes the nested host's subtree. Client rendering never writes it and it is never removed. The writer (internal/compiled/server) and readers (internal/compiled/runtime) import this constant; nothing writes the literal.

The wire-validator face of the one canonical attribute-name predicate (delegates to `./forbidden-sinks.ts`); exported for parity tests.

An event binding scoped to each item of an `each` region. The runtime attaches this listener to every item root node created by the region, making per-item handlers (onClick={this.select(row.id)}) expressible without fixed-path event parts.

event: string (必填) — DOM event name ('click', 'input', …).; handler: string (必填) — Handler method name on the compiled class.; action: ProgramEventAction (必填) — The action to dispatch, same union as fixed event parts.; selector?: string (可选) — Optional child selector within the item template (e.g. '.probe-button'). When omitted, the listener attaches to the item root.

The Part Program IR version this package defines (currently v1).

The comment marker closing a part anchor in serialized program markup.

toString: (radix?: number) => string (必填) — Returns a string representation of an object.; toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; valueOf: () => number (必填) — Returns the primitive value of the specified object.; toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

Anchor marker payloads shared by seed runtime consumers.

toString: (radix?: number) => string (必填) — Returns a string representation of an object.; toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; valueOf: () => number (必填) — Returns the primitive value of the specified object.; toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

The serializable Part Program v1: one compiled component as data.

version: 1 (必填); tag: string (必填); root: ProgramRoot (必填); template: ProgramTreeNode[] (必填); parts: ProgramPart[] (必填); regions: ProgramRegionRecord[] (必填); dependencies: ProgramDependencyRecord[] (必填); locations: ProgramLocationRecord[] (必填); sourceMap: ProgramSourceMap (必填) — Compile-time provenance. The canonical in-memory artifact always carries it; the serialized module payload omits it (no runtime consumer reads it), so the validator accepts programs with or without it but still verifies it strictly when present.; metadata: CompiledElementMetadata (必填)

The one deterministic program consumed by all execution modes.

version: 1 (必填); tag: string (必填); root: ProgramRoot (必填); template: ProgramTreeNode[] (必填); parts: ProgramPart[] (必填); regions: ProgramRegionRecord[] (必填); dependencies: ProgramDependencyRecord[] (必填); locations: ProgramLocationRecord[] (必填); sourceMap: ProgramSourceMap (必填) — Compile-time provenance. The canonical in-memory artifact always carries it; the serialized module payload omits it (no runtime consumer reads it), so the validator accepts programs with or without it but still verifies it strictly when present.; metadata: CompiledElementMetadata (必填)

String attribute sink bound to a Signal.

k: "attr" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Boolean attribute sink bound to a Signal.

k: "bool" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Specialized fixed sinks make ownership explicit for class and style text.

k: "class" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

One condition clause of a when part.

signal: string (必填); op: ConditionOperator (必填); value: string | number | boolean (必填)

One module dependency the compiled module graph records.

signal: string (必填); owner: { kind: "part" | "region"; index: number; } (必填); location: string (必填)

A list part: repeats its template node per item of a bound signal.

k: "each" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); key: string (必填); field?: string (可选) — Restatement of the item field for single-field templates; omitted when the item template binds multiple fields (each `ival`/`iattrs` slot then carries its own field).; item: ProgramTreeNode[] (必填); itemEvents?: ItemEventBinding[] (可选) — Per-item event bindings (#1556 IR v2): listeners attached to each item.; location: ProgramLocation (必填)

A static element node of the program tree.

k: "el" (必填); id: string (必填); tag: string (必填); attrs: [string, string][] (必填); iattrs?: [string, string][] (可选) — Per-item attribute slots ([name, itemField]) — valid only inside an `each` item template. At mount/claim time the value resolves from the current item: `true` emits a bare attribute, `false`/`null`/`undefined` omit it, anything else serializes with String().; children: ProgramTreeNode[] (必填)

The action one event part dispatches.

An event binding part: listener wiring between DOM event and action.

k: "event" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; event: string (必填); handler: string (必填); action: ProgramEventAction (必填); path: number[] (必填); location: ProgramLocation (必填)

Trusted-HTML content sink (alpha.9). The signal value must carry the runtime TrustedHtml capability; its HTML replaces the target element's content. The target's subtree is opaque to the claim path. The compiler emits this only for an explicit `innerHTML={this.<field>}` sink on an otherwise childless element — there is no implicit or discovery path to raw HTML.

k: "html" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

Item-value text slot; valid only inside an `each` item template. `field` names the item field rendered by this slot — multi-field item templates carry one slot per field, and the compiler always emits it.

k: "ival" (必填); field: string (必填)

Exact compiler-owned location for one dynamic sink or range anchor.

id: string (必填); kind: "anchor" | "sink" (必填); path: number[] (必填); node?: string (可选)

A location record also makes the identity auditable without inspecting parts.

The discriminated union of dynamic parts a program instantiates.

The anchor node marking where a part binds in the tree.

k: "part" (必填); id: string (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

Where a part sits relative to its anchor.

offset.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; offset.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; offset.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; offset.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; offset.valueOf: () => number (必填) — Returns the primitive value of the specified object.; offset.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; line: number (必填); column: number (必填)

DOM property sink bound to a Signal; `path` is retained for seed consumers.

k: "prop" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); name: string (必填); path: number[] (必填); location: ProgramLocation (必填)

A named ref slot is serializable; the generated class supplies the ref value.

k: "ref" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; ref: string (必填); path: number[] (必填); location: ProgramLocation (必填)

One region the program tracks: the boundaries of a dynamic subtree.

id: string (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; kind: "when" | "each" (必填); anchor: string (必填); end: string (必填); source: string (必填)

The root of one program tree: element, part anchor, or text.

id: "root" (必填); kind: RootMode (必填); nodes: string[] (必填)

The kind of source record a program source map entry carries.

The program source map: authored spans projected onto emitted records.

version: 1 (必填); file: string (必填); records: ProgramSourceRecord[] (必填)

A half-open [start, end) range into the authored source text.

file: string (必填); start: ProgramPosition (必填); end: ProgramPosition (必填)

One source-map record: the authored origin of one emitted node or part.

id: string (必填); kind: ProgramSourceKind (必填); source: ProgramSourceRange (必填)

A style binding part.

k: "style" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); path: number[] (必填); location: ProgramLocation (必填)

A static text node of the program tree.

k: "text" (必填); value: string (必填)

A text interpolation part bound to one signal.

k: "text" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); location: ProgramLocation (必填)

The discriminated union of static tree nodes.

A conditional part: swaps template branches on a condition.

k: "when" (必填); index.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; index.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; index.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; index.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; index.valueOf: () => number (必填) — Returns the primitive value of the specified object.; index.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; signal: string (必填); test: ProgramCondition (必填); on: ProgramTreeNode[] (必填); off: ProgramTreeNode[] (必填); location: ProgramLocation (必填)

The serialized value-type tag of a compiled property default.

How the compiled component attaches its root: light DOM or a shadow root.

The JSON-serializable value shape a compiled property default admits.

The one `<style>` element the server serializer emits as the first DSD template child when the class carries static styles (renderDsd parity — pages never upgrade, so their styles must ship in the payload). The claim path skips exactly this marked node; a marked node on a style-less class is claim drift and fails closed.

Validate an unknown value as a Part Program v1. The validator is intentionally strict: unknown instruction kinds, missing ownership records and unsafe paths fail before a runtime can guess at their meaning.

HTML void elements — the ONE canonical tag set for every serializer, validator, and compiler in the workspace (issue #1220, M4). This module is import-free and host-free by design: it sits at the base of the module graph so the DOM runtime (internal/core/html-escape.ts), the Part Program exchange artifact (internal/protocol/part-program.ts), and the compiler semantic core can all consume the same definition without an import cycle or a second source of truth. Content is the full HTML Standard void-element list, `param` included. Do not redefine this set anywhere else; internal/core/html-escape.ts and internal/protocol/part-program.ts re-export it, and __tests__/void-tags-convergence.test.ts enforces the single owner.

Idle-hydration scheduling fallback (milliseconds) when neither `requestIdleCallback` nor `requestAnimationFrame` is available.

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Nested element expansion depth bound for `renderDsd`: cyclic component composition fails closed instead of recursing without end.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Property on the stub holding the generated entry's registration-ownership map (tag -> class it registered): a route module that self-registers its tag wins over the entry's registration, and on dev re-evaluation a fresh self-registered class must still win (#952).

Property on the SSR registry holding the TRUE original `define` method, captured before the generated entry installs its idempotent wrapper. The registry outlives vite dev SSR module re-evaluations, so without this the second evaluation would capture the already-wrapped `define` as its "original" and every forced re-registration would silently early-return through the previous wrapper (#1339 lit dev feedback).

Marker property set to `true` on the SSR customElements stub. Readers must treat the marked registry as re-definable.

Per-render declarative-shadow-dom metrics the server records.

tagName: string (必填); renderTimeMs.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; renderTimeMs.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; renderTimeMs.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; renderTimeMs.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; renderTimeMs.valueOf: () => number (必填) — Returns the primitive value of the specified object.; renderTimeMs.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; templateSize: number (必填); layer: ComponentLayer (必填); hasError: boolean (必填); nestingDepth: number (必填)

The hydration delivery hint a component or route carries.

tagName: string (必填); layer: ComponentLayer (必填); hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选)

One render failure record the SSR pipeline reports.

code: string (必填); severity: "error" | "warning" (必填); phase: string (必填); tagName: string (必填); message: string (必填); recoverable: boolean (必填)

The public result of one `renderDsd()` call: the serialized DSD `html`, the render errors collected while composing it (empty on success), the render metrics for the root component, and the hydration hints the client scheduler reads to upgrade islands.

html: string (必填); errors: RenderError[] (必填); metrics: DsdRenderMetrics (必填); hydrationHints: HydrationHint[] (必填)

The build's admission verdict for one discovered tag: where the declaration lives (`modulePath`), how it was discovered (`source`), which render path it is admitted to, and the reason recorded for the manifest.

tagName: string (必填); modulePath: string (必填) — Module path of the island declaration. Empty for 'foreign' decisions: a foreign tag is consumed in JSX but declares no module the build owns.; source: "local" | "package" | "nested" | "foreign" (必填) — 'foreign' (#979): a third-party WC tag discovered by the foreign-tag scanner in page/island JSX — recorded for visibility only; SSR still treats it as an opaque passthrough (renderPath 'client-only').; renderPath: "ssr+client" | "client-only" | "rejected" (必填); reason: string (必填)

The host-neutral request handler every runtime adapter and generated server entry exposes: a WinterCG `(request, context?) => Response` with no server engine dialect baked in.

A host runtime adapter: exposes the fetch handler a server engine dispatches to.

name: string (必填); fetch: OpenElementRequestHandler<Env> (必填); prerender?: (() => AsyncIterable<RuntimePrerenderResult> | Iterable<RuntimePrerenderResult>) (可选)

Options one runtime adapter is constructed with.

name: string (必填); fetch: OpenElementRequestHandler<Env> (必填); prerender?: (() => AsyncIterable<RuntimePrerenderResult> | Iterable<RuntimePrerenderResult>) (可选)

runtime.ts - Runtime adapter protocol. Replacement boundary for Nitro, Workers, Node, Deno, or future fetch-compatible runtimes. Preserves openElement semantics while leaving concrete server engines outside this package.

env?: Env (可选); platform?: unknown (可选); params?: Record<string, string> (可选)

Read-only signal protocol used by computed values.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@2892.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Alias for APIs that accept either writable or read-only signals.

Runtime/type brand for signals created by the configured reactive engine.

Signal engine protocol used by the framework's built-in adapter. This is a deliberate internal seam, not a public compatibility contract: the framework layer talks to signals only through this narrow interface so its call sites stay implementation-agnostic. The package ships and verifies exactly one engine implementation (`preact-engine`, backed by `@preact/signals-core`). Preact's own API is not Element public API, and arbitrary third-party engines are not promised; any future engine would be added behind this protocol rather than inline (charter decision — see #723).

signal: <T>(initialValue: T) => WritableSignal<T> (必填); computed: <T>(fn: () => T) => ReadonlySignal<T> (必填); effect: (fn: () => void | Unsubscribe) => Unsubscribe (必填)

Minimal signal-like object accepted by renderers and bindings.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@2892.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Unsubscribe function returned by subscriptions and effects.

Writable signal protocol used by openElement integrations.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@2892.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

One API route declaration in the generated entry descriptor.

kind: "api" (必填); path: string (必填); varName: string (必填); filePath: string (必填); importPath: string (必填)

The app shell module a build resolves: tag, import path, and serialized props.

tagName: string (必填); importPath: string (必填); props: Record<string, unknown> (必填)

The resolved app shells a build ships: the default shell plus named layouts.

default: ResolvedAppShell (必填); layouts: Record<string, ResolvedAppShell> (必填)

Result returned by the OpenElement build pipeline.

pages: BuildPageArtifact[] (必填) — Generated HTML pages.; manifest: BuildManifestArtifact (必填) — Build manifest.; clientAssets: BuildClientAsset[] (必填) — Client-side assets (island bundles, CSS, etc).; warnings: string[] (必填) — Non-fatal warnings.; errors: string[] (必填) — Fatal errors.; success: boolean (必填) — Whether the build succeeded.

A single client asset emitted by the build pipeline.

fileName: string (必填); source: string | Uint8Array<ArrayBufferLike> (必填); sizeBytes.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; sizeBytes.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; sizeBytes.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; sizeBytes.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; sizeBytes.valueOf: () => number (必填) — Returns the primitive value of the specified object.; sizeBytes.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

i18n configuration for the build pipeline.

locales: string[] (必填); defaultLocale?: string (可选)

A single island input to the build pipeline.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); hydrate?: IslandDeliveryStrategy (可选); ssr?: boolean (可选); dsd?: boolean (可选); source?: "local" | "package" | "nested" (可选); reason?: string (可选)

Manifest produced by the build pipeline.

routes: { kind: "page" | "api"; path: string; tagName?: string; isDynamic: boolean; }[] (必填); islands: BuildIslandInput[] (必填); requestTimeRoutes?: string[] (可选) — Paths served at request time (renderIntent mode 'dynamic'). Absent for pure-static builds.

Output configuration for the build pipeline.

root?: string (可选) — Project root directory.; outDir?: string (可选) — Output directory relative to root.; base?: string (可选) — Base URL path.

Package island configuration for the build pipeline.

packages?: string[] (可选) — Package names that may expose island declarations.

A single generated HTML page artifact.

path: string (必填); html: string (必填); errors: { message: string; route?: string; }[] (必填) — Errors collected while rendering this page.

Framework-agnostic plan consumed by the OpenElement build pipeline.

options.renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; options.routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; options.islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; options.componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; options.packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; options.appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; options.layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; options.mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; options.headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; options.html?: { lang?: string; title?: string; } (可选) — Document `<html>` attributes: the `lang` the document declares and the default `<title>`.; options.inject?: { stylesheets?: Array<string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | bool… (可选) — Document head/body injection channels: external stylesheets, scripts, and trusted raw head fragments.; options.ssr?: { noExternal?: (string | RegExp)[]; } (可选) — SSR bundling switches; `noExternal` forces the named packages through the SSR bundle instead of an external import.; options.island?: { upgradeStrategy?: HydrationStrategy; } (可选) — Island defaults applied to every island the build discovers.; options.build?: { outDir?: string; manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; }; } (可选) — Build output switches: the output directory and the advisory manifest budgets.; options.viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; options.speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; options.middleware?: { cors?: boolean; corsOrigin?: string | string[]; corsOriginModule?: string; requestId?: boolean; logger?: boolean; securityHeaders?: boolean; csp?: { policy?:… (可选) — Request-time middleware switches, composed outside the framework handler.; routes: BuildRouteInput[] (必填) — Discovered page and API routes.; islands: BuildIslandInput[] (必填) — Discovered local and package islands.; output.root?: string (可选) — Project root directory.; output.outDir?: string (可选) — Output directory relative to root.; output.base?: string (可选) — Base URL path.; i18n?: BuildI18nOptions (可选) — i18n expansion options.; packageIslands.packages?: string[] (可选) — Package names that may expose island declarations.

A single route input to the build pipeline.

kind: "api" | "page" (必填) — Route kind: page or API.; path: string (必填) — Route path (e.g. '/about', '/blog/:slug').; filePath: string (必填) — Absolute or relative file path of the route module.; importPath: string (必填) — Import specifier used by generated entry code.; tagName?: string (可选) — Resolved tag name for page routes.; paramNames?: string[] (可选) — Dynamic segment names.; staticParams?: Record<string, string>[] (可选) — Static generation params produced by getStaticPaths().

Client island entry shape passed to entry generator.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); exportName?: string (可选) — Optional named export to register as the custom element constructor. When set (package islands whose chunk dropped `export default` per #638), the client island factory reads `mod[exportName]` instead of `mod.default`. When absent, the factory falls back to `mod.default` (local/route islands).; strategy: IslandDeliveryStrategy (必填); strategySource?: "default" | "manifest" | "component" | "route" (可选); ssr?: boolean (可选); dsd?: boolean (可选); reason?: string (可选)

The CORS origin policy an API route declares.

The content-security-policy directives a route or document declares.

policy?: string (可选); nonce?: boolean (可选); reportOnly?: boolean (可选)

The document-level facts a build bakes into the generated entry.

lang: string (必填); title: string (必填); headExtras: string (必填); allowHeadExtrasScripts: boolean (必填)

The full build-time description of one generated entry: routes, islands, renderers, middleware, document, and app-shell plans.

isSSG: boolean (必填); renderer?: "native" | "lit" (可选) — Page renderer selection (#1339). Absent/'native' keeps the compiled renderDsd page path byte-identical; 'lit' forks page tag resolution, page SSR and the client entry onto; imports: ImportDecl[] (必填); middleware: MiddlewareDecl[] (必填); fetchMiddleware?: string[] (可选) — `middleware.use` fetch middleware module paths (#858), in user-configured order. The entry renderer emits one `import * as __mw_N from '<path>'` per entry and composes each module's default export around the exported handler in onion order. Absent/empty when the app configures no fetch middleware, keeping the generated entry byte-identical to pre-#858 output.; apiRoutes: ApiRouteDecl[] (必填); pageRoutes: PageRouteDecl[] (必填); staticComponents: StaticComponentDecl[] (必填); islands: IslandDecl[] (必填); hasEnhancedForms?: boolean (可选) — True when any page route carries data-open-enhance forms (#569). Drives the dev island client script injection (#951): an island-free app with enhanced forms still needs the client entry in dev HTML.; ssrAdmissionPlan: SsrAdmissionPlan (必填); cemClassifications?: CompatibilityClassification[] (可选); renderers: RendererDecl[] (必填); middlewareScopes: MiddlewareScopeDecl[] (必填); document: DocumentConfig (必填); appShell: AppShellPlan (必填); upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); i18n?: { locales: string[]; defaultLocale: string; } (可选) — Declared project locales. Absent for a single-locale site: the generated entry then emits no locale prefixes and the default-locale fallback, which is byte-identical to pre-i18n output.

One module import the generated entry emits.

from: string (必填); names: string[] (必填); alias?: string (可选)

One island the build admits: tag, module path, and delivery facts.

tagName: string (必填); modulePath: string (必填); isPackage?: boolean (可选); exportName?: string (可选) — Optional named export to register as the custom element constructor. Set for package islands from the manifest declaration's `className` (the CEM-derived export class name), so the client island factory can read `mod[exportName]` after #638 removed `export default` from UI component chunks. Absent for local/route islands (which use default).; hydrate?: IslandDeliveryStrategy (可选); ssr?: boolean (可选); dsd?: boolean (可选); authoring?: "basic-element" | "third-party-wc" (可选); source?: "local" | "package" | "nested" (可选); reason?: string (可选)

Adapter-owned browser delivery strategy, including media-query admission.

One middleware module the generated entry composes.

kind: "requestId" | "logger" | "cors" | "securityHeaders" | "csp" (必填); comment?: string (可选); config.corsOrigin?: CorsOriginConfig (可选); config.corsOriginModule?: string (可选) — Normalized import path of a module default-exporting `(origin: string) => string | undefined`. The generated entry imports the module and passes its default export to `cors({ origin })` — the callback is referenced, never serialized.; config.warnOnDefaultCors?: boolean (可选) — #1411: emit the default-CORS production advisory. Absent means "warn" (production builds); the dev server sets false so the first run is warning-free.; config.csp?: CspConfig (可选)

The scope one middleware applies to (all routes or a named route set).

varName: string (必填); scope: string (必填); importPath: string (必填)

One page route declaration in the generated entry descriptor.

kind: "page" (必填); path: string (必填); varName: string (必填); filePath: string (必填); defaultTagName: string (必填); tagName: string (必填); importPath: string (必填); isDynamic?: boolean (可选); paramNames?: string[] (可选); streamManifest?: StreamRouteManifest (可选)

One page renderer module registration.

varName: string (必填); scope: string (必填); importPath: string (必填); depth.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; depth.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; depth.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; depth.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; depth.valueOf: () => number (必填) — Returns the primitive value of the specified object.; depth.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.

The resolved shell for one plan slot: disabled (false) or a full declaration.

A single route metadata entry emitted as `routeInfo` by the generated SSG entry module (see entry-render-ssg.ts).

path: string (必填); filePath?: string (可选) — Route module file path. Read by the render pipeline: ssg-render.ts copies it into server-manifest.json for request-time (renderIntent 'dynamic') routes.; tagName: string (必填); module?: unknown (可选) — The route module namespace object (typed per-module at codegen time).; isDynamic: boolean (必填); paramNames: string[] (必填); rendering?: string (可选) — Rendering mode declared via renderIntent.mode ("static" when unset; the "auto" alias is rejected, #609).; hasAction?: boolean (可选) — True when the route module exports an action (request-time form POST).; streamManifest?: StreamRouteManifest (可选); params?: Record<string, string> (可选)

Speculation Rules configuration for SSG post-processing

prerender?: string[] (可选) — URL patterns to prerender (fully render in background before navigation).; prefetch?: string[] (可选) — URL patterns to prefetch (fetch HTML + resources without rendering).; exclude?: string[] (可选) — URL patterns to exclude from both prefetch and prerender.; eagerness?: "immediate" | "moderate" | "conservative" (可选) — Eagerness level for prerender rules.

User-facing SSG build behavior switches (OpenElementOptions['ssg']).

dynamicRouteFailure?: "fail" | "warn" (可选) — Policy for dynamic-route render failures during SSG. See {@link SsgRenderOptions.dynamicRouteFailure}.

Per-page render diagnostics returned by renderRoute()

html: string (必填) — Rendered HTML string; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; redirect?: { location: string; status: number; } (可选) — Redirect outcome (3xx). When set, `html` holds an interim status page and the result must not be persisted as a normal 200 page.; notFound?: boolean (可选) — True when the route signalled not-found (404).; errors: RenderError[] (必填) — Render errors collected during rendering; componentCount: number (必填) — Number of DSD components rendered on this page; renderTimeMs: number (必填) — Total render time for all components on this page (ms)

The per-build render evidence record the SSG engine emits for audit.

i18nOptions?: { [key: string]: unknown; locales: string[]; defaultLocale?: string; } | null (可选); admissionDecisions?: SsrAdmissionDecision[] (可选) — SSR admission decisions from the plan that rendered the pages.; manifestBudget.islandKB?: number (可选); manifestBudget.totalJsKB?: number (可选); manifestBudget.pageKB?: number (可选); onPrintBuildManifest?: ((input: { root: string; outDir: string; phase: 3; headExtras?: string; budget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; }; }) => void | Prom… (可选)

Options passed to the shared SSG render pipeline.

root: string (必填); outDir: string (必填); base?: string (可选); headExtras?: string (可选); html.lang?: string (可选); html.title?: string (可选); middleware.csp?: { policy?: string; reportOnly?: boolean; nonce?: boolean; } (可选); upgradeStrategy?: string (可选); viewTransition?: boolean (可选); speculation?: boolean | Record<string, unknown> (可选); islandTagNames?: string[] (可选); routesDir?: string (可选); dynamicRouteFailure?: "fail" | "warn" (可选) — Policy for dynamic-route render failures (HTTP status >= 500, non-empty render errors, or a renderRoute throw) during SSG. - 'fail' (default): abort the build - a failed page must never ship as a normal 200 page. - 'warn': log the failure and skip the page (the page is not written and is not registered in the ISR manifest).

Summary of an SSG render run, returned by ssgRender().

staticNon200: { path: string; status: number; }[] (必填) — Static routes whose handler returned a non-200 status. hono/ssg drops these responses (defaultPlugin), so they are not written to disk; they are listed here and in the build log instead of disappearing silently.; warnings: string[] (必填) — Non-fatal warnings collected during the SSG run (sitemap generation failures, etc.). Surfaced here so the build summary / release evidence carries them instead of letting them disappear silently.

The build-time SSR admission decisions per component tag.

renderableTags: string[] (必填); clientOnlyTags: string[] (必填); rejectedTags: string[] (必填); reasons: Record<string, string> (必填); decisions: SsrAdmissionDecision[] (必填); cemClassifications?: CompatibilityClassification[] (可选); foreignTags?: string[] (可选) — #979: foreign custom-element tags discovered in page / island JSX that are neither local islands, package-manifest islands, nor openElement-authored elements. Visibility only — each tag also carries a source:'foreign' decision (renderPath 'client-only') and the SSR/behavior is unchanged (opaque passthrough).

The server bundle facts the SSG engine consumes for stream rendering.

Build-host-only compiled component reached through a route's local import graph. These components participate in recursive SSR/SSG expansion but are not client islands and therefore add no hydration or browser entry.

tagName: string (必填); modulePath: string (必填); compilerInteractionEvents: string[] (必填) — Compiler-owned interaction events; empty means no inferred browser entry.

Build-only route projection bound to a specific compiled page program.

program: { version: number; tag: string; sha256: string; } (必填); fields: { field: string; signal: string; owners: Array<{ kind: "part" | "region"; index: number; location: string; source: PartProgramV1["sourceMap"]["records"][number… (必填)

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Whether a static attribute (name/value as authored into the Part Program) makes a streamed frame unsafely installable: event-handler, seed-spoofing, and srcdoc names fail outright, and URL-carrying names fail when the entity-decoded, control-stripped value carries a script scheme.

Minimal stylesheet contract (replaceSync + cssRules) satisfied by native and shim sheets.

replaceSync: (text: string) => void (必填); cssRules: StyleSheetRule[] (必填)

Cross-environment CSSStyleSheet abstraction. In browsers this delegates to the native CSSStyleSheet API. In SSR runtimes it falls back to a minimal in-memory implementation that exposes the subset used by OpenElement and renderDsd().

cssText: string (必填)

HTML void elements — the ONE canonical tag set for every serializer, validator, and compiler in the workspace (issue #1220, M4). This module is import-free and host-free by design: it sits at the base of the module graph so the DOM runtime (internal/core/html-escape.ts), the Part Program exchange artifact (internal/protocol/part-program.ts), and the compiler semantic core can all consume the same definition without an import cycle or a second source of truth. Content is the full HTML Standard void-element list, `param` included. Do not redefine this set anywhere else; internal/core/html-escape.ts and internal/protocol/part-program.ts re-export it, and __tests__/void-tags-convergence.test.ts enforces the single owner.

Route action: handles form submissions for a page route.

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Context passed to a route action function (extends loader context).

formData: FormData (必填); request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Wire shape returned to the JavaScript form-enhancement path. The no-JS path never sees this: it gets the equivalent semantics as plain HTTP (303 on success, 422 with the re-rendered form on validation failure, redirect/error as status codes). Success carries no data envelope. The application-loop contract makes a successful non-GET action answer 303 (PRG) — the framework never answers 200 with a rendered page, or with a success document, for a successful mutation — so the fetch channel answers `{ type: 'redirect' }` naming the PRG target and the authored return value is discarded by design. Success data travels the PRG target instead (query state the loader re-runs with, which the props projector then maps; see the router guide's "Form actions" section). The union previously declared a `{ type: 'success' }` member that no code path ever emitted — removed so the type matches the wire. Error outcomes (CSRF 403, unknown action 404, unparseable body 400, unexpected 500) are NOT part of this union: since #863 they answer RFC 9457 Problem Details with the PROBLEM_JSON_MEDIA_TYPE content type — see ProblemDetails.

Application shell declaration: `false` disables the shell entirely, `'default'` uses the built-in shell, and the object form names a tag with the module path that defines it (`import`, resolved like a {@link FrameworkOptions.middleware.use } entry) plus the compiled shell properties the router injects per route.

Assert that a tag name is a valid custom element name.

Collect all public (non-internal) own properties from a host object. Keys starting with `__openElement` are framework-internal and excluded. Uses Reflect.get for safe access (respects getters); a getter that throws is skipped with a warning so one bad prop cannot take the tree down.

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

The delivery layer a component belongs to: fully static DSD markup ('dsd-static'), DSD markup with a client island ('dsd-interactive'), a client-only island with no SSR output ('pure-island'), or a light-DOM element ('light-dom'). Recorded per component in the build manifest and consumed by the hydration scheduler.

Create a derived read-only signal recomputed from its dependencies.

Consumer-local reactive projection of a protocol context value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@3992: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@3994: string (必填); defaultValue: T (必填)

A typed context token: protocol identity (`key`) plus its default value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@3992: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@3994: string (必填); defaultValue: T (必填)

Create a typed context token shared between provider and consumer elements.

toString: () => string (必填) — Returns a string representation of an object.; valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; __@toPrimitive@3992: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; __@toStringTag@3994: string (必填)

Create one request-local deferred shell from a generated route manifest. The manifest hash is checked against the exact runtime wire program before any shell can be produced.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Inputs for a request-scoped deferred DSD server executor.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Create a {@link Logger} that prefixes every message with `[tag]`.

Object prototype keys that must never be injected from untrusted props.

Resolve `id` (a `#hash` or bare id) against `root` and, when the id is not in that root's own tree, recurse into every nested shadow root. Returns the first match or `null`; a malformed percent-encoded id is not an error.

Initial shell, typed seed, and bounded updates for a deferred DSD request.

shell: string (必填); owner: DeferredServerOwner (必填); seed: Record<string, { state: "resolved"; type: string; value: unknown; } | { state: "pending"; type: string; } | { state: "missing"; type: string; }> (必填); resolvedValue: (field: string, value: unknown) => unknown (必填); serializeResolved: (field: string, value: unknown) => string[] (必填)

Maps route-local deferred fields to the compiled Part or Region owners they update.

program: { version: number; tag: string; sha256: string; } (必填); fields: readonly { field: string; signal: string; owners: readonly { kind: "part" | "region"; index: number; }[]; }[] (必填)

The same document serialization boundary, with only body wrappers left open.

title?: string (可选); lang?: string (可选); clientScript?: string (可选); scripts?: DocumentScriptDescriptor[] (可选); meta.description?: string (可选); meta.tags?: Record<string, string | number | boolean>[] (可选); devScripts?: string (可选); headExtras?: string (可选); dangerouslyHeadFragments?: string[] (可选); allowHeadExtrasScripts?: boolean (可选); links?: { rel: string; href: string; hreflang?: string; }[] (可选); structuredData?: readonly Record<string, unknown>[] (可选); cspNonce?: string (可选); streamBootstrap?: string (可选) — Trusted framework bootstrap emitted synchronously in the document head.

Run a side effect that re-subscribes whenever its signal dependencies change.

Compiler-recognized element decorator; inert no-op at runtime.

Install (once per document) framework-level fragment navigation: a same-document anchor click whose target lives inside a nested shadow root scrolls to it and pushes the hash instead of being dropped by the browser. `{ enabled: false }` opts an application out.

enabled?: boolean (可选) — Set false before installation to opt out for an application.

Install the bounded pre-upgrade interaction capture on an owning root (default: the document). Generated client entries call this with their declared island tags before any compiled element upgrades; after a successful claim the element replays the captured events whose targets live inside its root (compiled claim capture/replay, internal/compiled/runtime.ts). Idempotent per root (repeat calls merge tags, never reinstall listeners) and a no-op where no DOM exists (SSR). Invariant: the capture itself — one fixed listener set per owning root, installed once per page — is page-lifetime by design and is NOT the leak. The M1 leak was retained event-target records; each element releases exactly its own records at its activation decision (success or failure), while records owned by still-pending elements survive for their delayed/lazy upgrade (#1170). Boundedness: the facade capture passes the declared-island filter, so only interactions under a still-pending DECLARED island tag enter the queue — ordinary events and undeclared third-party custom elements are skipped (nested pending declared islands still capture through their own unsettled host). With no tags declared the legacy dash heuristic applies. The shared queue carries a hard capacity cap (fail closed), detached records are swept when a claim root adopts its share (and under queue pressure), and each activation decision deterministically empties that root's own bucket, so post-hydration traffic and removals never grow retention.

addEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: AddEventListenerOptions | boolean) => void (必填) — The **`addEventListener()`** method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target. [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/addEventListener); dispatchEvent: (event: Event) => boolean (必填) — The **`dispatchEvent()`** method of the EventTarget sends an Event to the object, (synchronously) invoking the affected event listeners in the appropriate order. The normal event processing rules (including the capturing and optional bubbling phase) also apply to events dispatched manually with dispatchEvent(). [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/dispatchEvent); removeEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: EventListenerOptions | boolean) => void (必填) — The **`removeEventListener()`** method of the EventTarget interface removes an event listener previously registered with EventTarget.addEventListener() from the target. The event listener to be removed is identified using a combination of the event type, the event listener function itself, and various optional options that may affect the matching process; see Matching event listeners for removal.…

Error message prefix for all openElement errors.

Base class for elements that catch descendant render/hydration errors and apply a retry policy.

Callback receiving every reported {@linkcode OpenElementError} for telemetry.

Escape an HTML attribute value. Delegates to `escapeHtml` so both share the single `ESCAPE_MAP` and the same single-pass replacement (consolidated in #633). Empty-value conventions remain intentionally distinct by design: - `escapeHtml` returns '' for non-string input. - `escapeAttrValue` (below) coerces via `String()` and is the boundary meant for unknown/variable attribute values.

Escape the five HTML-significant characters in text content.

Format an unknown thrown value as a human-readable string.

The adapter-facing framework options: where routes, islands and components live, which renderer serializes pages, the application shell and layout declarations, the document `<html>`/head injection channels, and the request-time middleware switches. Every field is optional; the adapter applies its documented default. This is the type an application config file's default export is checked against, so the rendered option table and the actual config surface cannot drift.

renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; html.lang?: string (可选); html.title?: string (可选); inject.stylesheets?: (string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | boolean>; })[] (可选) — Stylesheets linked into the document head; each entry is an href or a link record with integrity/crossorigin/attrs.; inject.scripts?: (string | { src: string; type?: string; async?: boolean; defer?: boolean; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<str… (可选) — Scripts emitted into the document; each entry is a src or a script record with type/async/defer/integrity/crossorigin/attrs.; inject.headFragments?: string[] (可选) — @dangerous fragments injected as-is. Trust boundary (same level as `trustedHtml`): never concatenate user-controlled content into these fragments; sanitize untrusted data at your own system boundary first. The framework only enforces no-`<script>` and no-executable-`<style>`.; ssr.noExternal?: (string | RegExp)[] (可选); island.upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); build.outDir?: string (可选) — Output directory for the build artifacts. Defaults to `dist`.; build.manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; } (可选) — Advisory only: exceeded budgets print build-manifest warnings and never fail the build; enforce them in your own build-output test.; viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; middleware.cors?: boolean (可选) — Enable the built-in CORS middleware.; middleware.corsOrigin?: string | string[] (可选) — Static CORS allowlist data, serialized into the generated entry as JSON. Mutually exclusive with {@link FrameworkOptions.middleware.corsOriginModule }.; middleware.corsOriginModule?: string (可选) — Path to a module that default-exports `(origin: string) => string | undefined`. The generated entry imports the module — the callback is never serialized — so it may close over module scope and import dependencies. Resolved with the same idiom as `appShell.import` (e.g. './app/cors-origin.ts'). Mutually exclusive with `corsOrigin`.; middleware.requestId?: boolean (可选) — Emit and honor a per-request id header.; middleware.logger?: boolean (可选) — Log each request through the built-in logger.; middleware.securityHeaders?: boolean (可选) — Attach the built-in security response headers.; middleware.csp?: { policy?: string; nonce?: boolean; reportOnly?: boolean; } (可选) — Content-Security-Policy emission: the policy string, nonce generation, and report-only mode.; middleware.use?: string[] (可选) — Fetch middleware chain (#858), composed around the framework handler in onion order (`use[0]` outermost), outside all built-in middleware above. Each entry is a MODULE PATH (same resolution idiom as `appShell.import`, e.g. './app/middleware/auth.ts') whose default export is a {@link Middleware}; the generated entry emits `import * as __mw_N from '<path>'` and composes `__mw_N.default` in configur…

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Idle-hydration scheduling fallback (milliseconds) when neither `requestIdleCallback` nor `requestAnimationFrame` is available.

Safely assign caller-supplied props onto a target object, skipping keys that could enable prototype pollution and tolerating read-only properties. The canonical guarded assigner for the canonical dangerous-key rule (#903, #1214): the

Shared dangerous-key predicate (#903, #1214). Prototype-internal keys must never be injected from untrusted props on ANY path: host prop collection (collectPublicProps / normalizePublicProps in props-utils.ts), guarded assignment (injectPropsSafe below — the SPA bootstrap page-projection write boundary in

Per-island delivery options (hydration strategy, SSR/DSD participation).

hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选) — Hydration strategy: - 'load': load immediately when module is imported - 'idle': defer to requestIdleCallback (default) - 'visible': use IntersectionObserver to defer until element is visible - 'only': client-only render, no DSD/SSR output Named `hydrate` to match `defineIslandConfig()` in the Router package — one option name across both packages.; dsd?: boolean (可选) — Whether to use DSD for SSR rendering of this island. Honored by the build-side island scan (via `defineIslandConfig`), not by `defineIsland()` itself: passing it in `IslandOptions` has no runtime effect.; ssr?: boolean (可选) — Whether this island may be admitted into server rendering. Like `dsd`, decided by the build-side island scan; inert when passed to `defineIsland()`.

Shared safe-attribute-name predicate (#1033): the SSR face of the one canonical predicate in `../protocol/forbidden-sinks.ts`. A name must be valid HTML attribute-name grammar (blocks quote/space injection, #602), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/`srcdoc`). The compiler, protocol validator, and server serializer enforce the same predicate with their own failure strategies; every path delegates to the single implementation, so the boundary cannot diverge.

Check if a tag name is a valid custom element name per HTML spec.

Route loader: fetches data for a page route.

Context passed to a request-time ('dynamic') route loader.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Locale-aware resolved path contract.

locale: string (必填); path: string (必填); localizedPath: string (必填); isDefaultLocalePath: boolean (必填)

logger.ts - Tagged console logger. Lightweight scoped logger. Returns plain functions so it is tree-shakable and has zero class overhead.

debug: (msg: string, ...args: unknown[]) => void (必填); info: (msg: string, ...args: unknown[]) => void (必填); warn: (msg: string, ...args: unknown[]) => void (必填); error: (msg: string, ...args: unknown[]) => void (必填)

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Nested element expansion depth bound for `renderDsd`: cyclic component composition fails closed instead of recursing without end.

Fetch middleware contract (#858): WinterCG shape, dialect-free — no Hono/h3 context object. Composed at the handler boundary in onion order (`use[0]` is outermost: it sees the request first and the response last), so it runs with identical semantics in the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry. A middleware may short-circuit by returning a Response without calling `next()`, or post-process the Response that `next()` returns. Module contract: a Middleware is the DEFAULT EXPORT of a module referenced from `middleware.use` by path (e.g. './app/middleware/auth.ts'). The generated server entry imports the module, so the middleware may close over module scope and import local helpers and third-party packages — it is a real module in the server module graph, never serialized source.

Custom Element base class for the compiled Part Program architecture. Subclasses are produced by the compiler; hand-written subclasses that never pass through the compiler fail closed at connect time.

One documented attribute of a custom element declaration.

name: string (必填); type?: string (可选); default?: string (可选); description?: string (可选); reflects?: boolean (可选); fieldName?: string (可选)

One documented CSS part of a custom element declaration.

name: string (必填); description?: string (可选)

One custom element declaration in a package manifest: tag, members and delivery metadata.

tagName: string (必填); className?: string (可选); superclassName?: string (可选); attributes?: OpenElementAttribute[] (可选); events?: OpenElementEvent[] (可选); slots?: OpenElementSlot[] (可选); cssParts?: OpenElementCssPart[] (可选); openElement.ssr?: boolean (可选); openElement.dsd?: boolean (可选); openElement.layer?: ComponentLayer (可选); openElement.hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); openElement.status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; openElement.module?: string (可选); openElement.export?: string (可选); description?: string (可选)

Framework error carrying a stable code, severity, phase and recoverability contract.

One documented custom event of a custom element declaration.

name: string (必填); type?: string (可选); description?: string (可选)

Package manifest of component declarations (not a Custom Elements Manifest).

schemaVersion: string (必填); packageName: string (必填); version: string (必填); description?: string (可选); author?: string (可选); license?: string (可选); homepage?: string (可选); repository?: string (可选); declarations: OpenElementDeclaration[] (必填)

Host-agnostic route and asset contracts shared by app and build drivers.

One node of the host-agnostic route tree: the matched URL `path` and route kind, the source and module paths the drivers resolve, the optional registered tag and param names, and the nested `children`.

kind: OpenElementRouteKind (必填); path: string (必填); filePath?: string (可选); importPath?: string (可选); tagName?: string (可选); paramNames?: string[] (可选); children?: OpenElementRouteNode[] (可选); meta?: Record<string, unknown> (可选)

One documented slot of a custom element declaration.

name: string (必填); description?: string (可选)

Media type of the RFC 9457 action error channel (#863).

RFC 9457 Problem Details document (#863): the action error channel answers `application/problem+json` instead of the bespoke `{ type: 'error', error: { message } }` JSON, so HTTP tooling recognizes failures natively. With `type: 'about:blank'`, `title` is the HTTP reason phrase and `detail` carries the specific explanation. The wire shape is alpha-unfrozen; the 1.0 acceptance freezes it in this problem+json form.

type: string (必填) — URI reference identifying the problem type; 'about:blank' when none applies.; title: string (必填) — Short human-readable summary (the HTTP reason phrase for 'about:blank').; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; detail?: string (可选) — Human-readable explanation specific to this occurrence.

Compiler-recognized property decorator; inert no-op at runtime.

reflect: boolean (必填); attribute?: string | false (可选); type?: unknown (可选); converter?: unknown (可选)

Provide a plain protocol value; the provider Signal remains OE-private.

Read-only signal protocol used by computed values.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@4106.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Server-render one compiled element through canonical Element composition.

Options for one `renderDsd()` call: the compiled component class to serialize, the values projected onto its compiled properties, optional route/source diagnostics metadata, the nested compiled tags the build admitted, and trusted parent-owned light children keyed by slot name.

componentClass?: CustomElementConstructor (可选); props?: Record<string, unknown> (可选); sourceInfo.route?: string (可选); sourceInfo.source?: string (可选); ssrRenderableTags?: readonly string[] (可选) — Build-admitted nested compiled tags. Omitted means shell-only rendering.; projectedChildren?: ReadonlyMap<string, TrustedHtml> (可选) — Trusted parent-owned light children keyed by slot name.

Recoverable render-phase error carrying the failing component path and tag.

The public result of one `renderDsd()` call: the serialized DSD `html`, the render errors collected while composing it (empty on success), the render metrics for the root component, and the hydration hints the client scheduler reads to upgrade islands.

html: string (必填); errors: RenderError[] (必填); metrics: DsdRenderMetrics (必填); hydrationHints: HydrationHint[] (必填)

Report an {@linkcode OpenElementError} to the telemetry hook, or console.error when none is installed.

code: string (必填); severity: ErrorSeverity (必填); phase: ErrorPhase (必填); recoverable: boolean (必填); statusCode.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; statusCode.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; statusCode.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; statusCode.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; statusCode.valueOf: () => number (必填) — Returns the primitive value of the specified object.; statusCode.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; toJSON: () => Record<string, unknown> (必填); name: string (必填); message: string (必填); stack?: string (可选); cause?: unknown (可选)

One route admitted by the scanner: URL `path`, source `filePath`, the route `type`, the generated variable name (`varName`) the entry binds it to, and the optional registration tag. {@link RouteEntry.definePage} and {@link RouteEntry.hasEnhancedForms} carry the two source-derived admission facts the generated entries branch on.

path: string (必填); filePath: string (必填); type: "page" | "api" | "island" | "special" (必填); varName: string (必填); tagName?: string (可选); definePage?: boolean (可选) — True when the route module's default export is a definePage() definition (#960 — registration decoupling). The generated entry registers the page class under the path-derived fallback tag and IGNORES the tagName export for registration: on a definePage route the export only names a content element. Plain element routes keep tagName as their registration tag.; source?: string (可选) — Source text captured during scanning when includeSource is enabled.; hasEnhancedForms?: boolean (可选) — True when the page route source carries data-open-enhance (#569): the client entry must ship the form-enhancement layer even when the app has zero islands.; special?: SpecialFileType (可选); params?: string[] (可选)

Canonical request-time/SSG server route context.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Context passed to a request-time ('dynamic') route loader. This is the server contract: the loader runs on the server with the Web-standard request, matched route params, the host environment and the platform object, and signals validation failure via fail()/redirect().

path: string (必填); filePath: string (必填)

Install the process-wide error telemetry hook (replaceable for tests, HMR, multi-app pages).

Create a writable signal through the selected signal engine.

Alias for APIs that accept either writable or read-only signals.

Special file kinds the route scanner recognizes by filename: `renderer` and `middleware`.

The build's admission verdict for one discovered tag: where the declaration lives (`modulePath`), how it was discovered (`source`), which render path it is admitted to, and the reason recorded for the manifest.

tagName: string (必填); modulePath: string (必填) — Module path of the island declaration. Empty for 'foreign' decisions: a foreign tag is consumed in JSX but declares no module the build owns.; source: "local" | "package" | "nested" | "foreign" (必填) — 'foreign' (#979): a third-party WC tag discovered by the foreign-tag scanner in page/island JSX — recorded for visibility only; SSR still treats it as an opaque passthrough (renderPath 'client-only').; renderPath: "ssr+client" | "client-only" | "rejected" (必填); reason: string (必填)

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Cross-realm StyleSheet constructor: the native CSSStyleSheet or the internal shim.

Minimal stylesheet contract (replaceSync + cssRules) satisfied by native and shim sheets.

replaceSync: (text: string) => void (必填); cssRules: StyleSheetRule[] (必填)

Mark an HTML string as trusted for explicit `innerHTML` sinks (the trust does not serialize).

Opaque capability marking HTML the application has explicitly vetted as trusted.

html: string (必填)

Whether a static attribute (name/value as authored into the Part Program) makes a streamed frame unsafely installable: event-handler, seed-spoofing, and srcdoc names fail outright, and URL-carrying names fail when the entity-decoded, control-stripped value carries a script scheme.

Wrap rendered HTML in a full HTML document. Adds DOCTYPE, head (title, meta, preload), and body. Supports CSP nonce and dev scripts (e.g. Vite client, route module registration).

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Assert that a tag name is a valid custom element name.

Object prototype keys that must never be injected from untrusted props.

Error message prefix for all openElement errors.

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Safely assign caller-supplied props onto a target object, skipping keys that could enable prototype pollution and tolerating read-only properties. The canonical guarded assigner for the canonical dangerous-key rule (#903, #1214): the

Shared dangerous-key predicate (#903, #1214). Prototype-internal keys must never be injected from untrusted props on ANY path: host prop collection (collectPublicProps / normalizePublicProps in props-utils.ts), guarded assignment (injectPropsSafe below — the SPA bootstrap page-projection write boundary in

Shared safe-attribute-name predicate (#1033): the SSR face of the one canonical predicate in `../protocol/forbidden-sinks.ts`. A name must be valid HTML attribute-name grammar (blocks quote/space injection, #602), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/`srcdoc`). The compiler, protocol validator, and server serializer enforce the same predicate with their own failure strategies; every path delegates to the single implementation, so the boundary cannot diverge.

Check if a tag name is a valid custom element name per HTML spec.

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Framework error carrying a stable code, severity, phase and recoverability contract.

Media type of the RFC 9457 action error channel (#863).

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Route action: handles form submissions for a page route.

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Context passed to a route action function (extends loader context).

formData: FormData (必填); request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Wire shape returned to the JavaScript form-enhancement path. The no-JS path never sees this: it gets the equivalent semantics as plain HTTP (303 on success, 422 with the re-rendered form on validation failure, redirect/error as status codes). Success carries no data envelope. The application-loop contract makes a successful non-GET action answer 303 (PRG) — the framework never answers 200 with a rendered page, or with a success document, for a successful mutation — so the fetch channel answers `{ type: 'redirect' }` naming the PRG target and the authored return value is discarded by design. Success data travels the PRG target instead (query state the loader re-runs with, which the props projector then maps; see the router guide's "Form actions" section). The union previously declared a `{ type: 'success' }` member that no code path ever emitted — removed so the type matches the wire. Error outcomes (CSRF 403, unknown action 404, unparseable body 400, unexpected 500) are NOT part of this union: since #863 they answer RFC 9457 Problem Details with the PROBLEM_JSON_MEDIA_TYPE content type — see ProblemDetails.

Application shell declaration: `false` disables the shell entirely, `'default'` uses the built-in shell, and the object form names a tag with the module path that defines it (`import`, resolved like a {@link FrameworkOptions.middleware.use } entry) plus the compiled shell properties the router injects per route.

Assert that a tag name is a valid custom element name.

Collect all public (non-internal) own properties from a host object. Keys starting with `__openElement` are framework-internal and excluded. Uses Reflect.get for safe access (respects getters); a getter that throws is skipped with a warning so one bad prop cannot take the tree down.

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

The delivery layer a component belongs to: fully static DSD markup ('dsd-static'), DSD markup with a client island ('dsd-interactive'), a client-only island with no SSR output ('pure-island'), or a light-DOM element ('light-dom'). Recorded per component in the build manifest and consumed by the hydration scheduler.

Create a derived read-only signal recomputed from its dependencies.

Consumer-local reactive projection of a protocol context value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@5195: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@5197: string (必填); defaultValue: T (必填)

A typed context token: protocol identity (`key`) plus its default value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@5195: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@5197: string (必填); defaultValue: T (必填)

Create a typed context token shared between provider and consumer elements.

toString: () => string (必填) — Returns a string representation of an object.; valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; __@toPrimitive@5195: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; __@toStringTag@5197: string (必填)

Create one request-local deferred shell from a generated route manifest. The manifest hash is checked against the exact runtime wire program before any shell can be produced.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Inputs for a request-scoped deferred DSD server executor.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Create a {@link Logger} that prefixes every message with `[tag]`.

Object prototype keys that must never be injected from untrusted props.

Resolve `id` (a `#hash` or bare id) against `root` and, when the id is not in that root's own tree, recurse into every nested shadow root. Returns the first match or `null`; a malformed percent-encoded id is not an error.

Initial shell, typed seed, and bounded updates for a deferred DSD request.

shell: string (必填); owner: DeferredServerOwner (必填); seed: Record<string, { state: "resolved"; type: string; value: unknown; } | { state: "pending"; type: string; } | { state: "missing"; type: string; }> (必填); resolvedValue: (field: string, value: unknown) => unknown (必填); serializeResolved: (field: string, value: unknown) => string[] (必填)

Maps route-local deferred fields to the compiled Part or Region owners they update.

program: { version: number; tag: string; sha256: string; } (必填); fields: readonly { field: string; signal: string; owners: readonly { kind: "part" | "region"; index: number; }[]; }[] (必填)

The same document serialization boundary, with only body wrappers left open.

title?: string (可选); lang?: string (可选); clientScript?: string (可选); scripts?: DocumentScriptDescriptor[] (可选); meta.description?: string (可选); meta.tags?: Record<string, string | number | boolean>[] (可选); devScripts?: string (可选); headExtras?: string (可选); dangerouslyHeadFragments?: string[] (可选); allowHeadExtrasScripts?: boolean (可选); links?: { rel: string; href: string; hreflang?: string; }[] (可选); structuredData?: readonly Record<string, unknown>[] (可选); cspNonce?: string (可选); streamBootstrap?: string (可选) — Trusted framework bootstrap emitted synchronously in the document head.

Run a side effect that re-subscribes whenever its signal dependencies change.

Compiler-recognized element decorator; inert no-op at runtime.

Install (once per document) framework-level fragment navigation: a same-document anchor click whose target lives inside a nested shadow root scrolls to it and pushes the hash instead of being dropped by the browser. `{ enabled: false }` opts an application out.

enabled?: boolean (可选) — Set false before installation to opt out for an application.

Install the bounded pre-upgrade interaction capture on an owning root (default: the document). Generated client entries call this with their declared island tags before any compiled element upgrades; after a successful claim the element replays the captured events whose targets live inside its root (compiled claim capture/replay, internal/compiled/runtime.ts). Idempotent per root (repeat calls merge tags, never reinstall listeners) and a no-op where no DOM exists (SSR). Invariant: the capture itself — one fixed listener set per owning root, installed once per page — is page-lifetime by design and is NOT the leak. The M1 leak was retained event-target records; each element releases exactly its own records at its activation decision (success or failure), while records owned by still-pending elements survive for their delayed/lazy upgrade (#1170). Boundedness: the facade capture passes the declared-island filter, so only interactions under a still-pending DECLARED island tag enter the queue — ordinary events and undeclared third-party custom elements are skipped (nested pending declared islands still capture through their own unsettled host). With no tags declared the legacy dash heuristic applies. The shared queue carries a hard capacity cap (fail closed), detached records are swept when a claim root adopts its share (and under queue pressure), and each activation decision deterministically empties that root's own bucket, so post-hydration traffic and removals never grow retention.

addEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: AddEventListenerOptions | boolean) => void (必填) — The **`addEventListener()`** method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target. [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/addEventListener); dispatchEvent: (event: Event) => boolean (必填) — The **`dispatchEvent()`** method of the EventTarget sends an Event to the object, (synchronously) invoking the affected event listeners in the appropriate order. The normal event processing rules (including the capturing and optional bubbling phase) also apply to events dispatched manually with dispatchEvent(). [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/dispatchEvent); removeEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: EventListenerOptions | boolean) => void (必填) — The **`removeEventListener()`** method of the EventTarget interface removes an event listener previously registered with EventTarget.addEventListener() from the target. The event listener to be removed is identified using a combination of the event type, the event listener function itself, and various optional options that may affect the matching process; see Matching event listeners for removal.…

Error message prefix for all openElement errors.

Base class for elements that catch descendant render/hydration errors and apply a retry policy.

Callback receiving every reported {@linkcode OpenElementError} for telemetry.

Escape an HTML attribute value. Delegates to `escapeHtml` so both share the single `ESCAPE_MAP` and the same single-pass replacement (consolidated in #633). Empty-value conventions remain intentionally distinct by design: - `escapeHtml` returns '' for non-string input. - `escapeAttrValue` (below) coerces via `String()` and is the boundary meant for unknown/variable attribute values.

Escape the five HTML-significant characters in text content.

Format an unknown thrown value as a human-readable string.

The adapter-facing framework options: where routes, islands and components live, which renderer serializes pages, the application shell and layout declarations, the document `<html>`/head injection channels, and the request-time middleware switches. Every field is optional; the adapter applies its documented default. This is the type an application config file's default export is checked against, so the rendered option table and the actual config surface cannot drift.

renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; html.lang?: string (可选); html.title?: string (可选); inject.stylesheets?: (string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | boolean>; })[] (可选) — Stylesheets linked into the document head; each entry is an href or a link record with integrity/crossorigin/attrs.; inject.scripts?: (string | { src: string; type?: string; async?: boolean; defer?: boolean; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<str… (可选) — Scripts emitted into the document; each entry is a src or a script record with type/async/defer/integrity/crossorigin/attrs.; inject.headFragments?: string[] (可选) — @dangerous fragments injected as-is. Trust boundary (same level as `trustedHtml`): never concatenate user-controlled content into these fragments; sanitize untrusted data at your own system boundary first. The framework only enforces no-`<script>` and no-executable-`<style>`.; ssr.noExternal?: (string | RegExp)[] (可选); island.upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); build.outDir?: string (可选) — Output directory for the build artifacts. Defaults to `dist`.; build.manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; } (可选) — Advisory only: exceeded budgets print build-manifest warnings and never fail the build; enforce them in your own build-output test.; viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; middleware.cors?: boolean (可选) — Enable the built-in CORS middleware.; middleware.corsOrigin?: string | string[] (可选) — Static CORS allowlist data, serialized into the generated entry as JSON. Mutually exclusive with {@link FrameworkOptions.middleware.corsOriginModule }.; middleware.corsOriginModule?: string (可选) — Path to a module that default-exports `(origin: string) => string | undefined`. The generated entry imports the module — the callback is never serialized — so it may close over module scope and import dependencies. Resolved with the same idiom as `appShell.import` (e.g. './app/cors-origin.ts'). Mutually exclusive with `corsOrigin`.; middleware.requestId?: boolean (可选) — Emit and honor a per-request id header.; middleware.logger?: boolean (可选) — Log each request through the built-in logger.; middleware.securityHeaders?: boolean (可选) — Attach the built-in security response headers.; middleware.csp?: { policy?: string; nonce?: boolean; reportOnly?: boolean; } (可选) — Content-Security-Policy emission: the policy string, nonce generation, and report-only mode.; middleware.use?: string[] (可选) — Fetch middleware chain (#858), composed around the framework handler in onion order (`use[0]` outermost), outside all built-in middleware above. Each entry is a MODULE PATH (same resolution idiom as `appShell.import`, e.g. './app/middleware/auth.ts') whose default export is a {@link Middleware}; the generated entry emits `import * as __mw_N from '<path>'` and composes `__mw_N.default` in configur…

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Idle-hydration scheduling fallback (milliseconds) when neither `requestIdleCallback` nor `requestAnimationFrame` is available.

Safely assign caller-supplied props onto a target object, skipping keys that could enable prototype pollution and tolerating read-only properties. The canonical guarded assigner for the canonical dangerous-key rule (#903, #1214): the

Shared dangerous-key predicate (#903, #1214). Prototype-internal keys must never be injected from untrusted props on ANY path: host prop collection (collectPublicProps / normalizePublicProps in props-utils.ts), guarded assignment (injectPropsSafe below — the SPA bootstrap page-projection write boundary in

Per-island delivery options (hydration strategy, SSR/DSD participation).

hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选) — Hydration strategy: - 'load': load immediately when module is imported - 'idle': defer to requestIdleCallback (default) - 'visible': use IntersectionObserver to defer until element is visible - 'only': client-only render, no DSD/SSR output Named `hydrate` to match `defineIslandConfig()` in the Router package — one option name across both packages.; dsd?: boolean (可选) — Whether to use DSD for SSR rendering of this island. Honored by the build-side island scan (via `defineIslandConfig`), not by `defineIsland()` itself: passing it in `IslandOptions` has no runtime effect.; ssr?: boolean (可选) — Whether this island may be admitted into server rendering. Like `dsd`, decided by the build-side island scan; inert when passed to `defineIsland()`.

Shared safe-attribute-name predicate (#1033): the SSR face of the one canonical predicate in `../protocol/forbidden-sinks.ts`. A name must be valid HTML attribute-name grammar (blocks quote/space injection, #602), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/`srcdoc`). The compiler, protocol validator, and server serializer enforce the same predicate with their own failure strategies; every path delegates to the single implementation, so the boundary cannot diverge.

Check if a tag name is a valid custom element name per HTML spec.

Route loader: fetches data for a page route.

Context passed to a request-time ('dynamic') route loader.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Locale-aware resolved path contract.

locale: string (必填); path: string (必填); localizedPath: string (必填); isDefaultLocalePath: boolean (必填)

logger.ts - Tagged console logger. Lightweight scoped logger. Returns plain functions so it is tree-shakable and has zero class overhead.

debug: (msg: string, ...args: unknown[]) => void (必填); info: (msg: string, ...args: unknown[]) => void (必填); warn: (msg: string, ...args: unknown[]) => void (必填); error: (msg: string, ...args: unknown[]) => void (必填)

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Nested element expansion depth bound for `renderDsd`: cyclic component composition fails closed instead of recursing without end.

Fetch middleware contract (#858): WinterCG shape, dialect-free — no Hono/h3 context object. Composed at the handler boundary in onion order (`use[0]` is outermost: it sees the request first and the response last), so it runs with identical semantics in the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry. A middleware may short-circuit by returning a Response without calling `next()`, or post-process the Response that `next()` returns. Module contract: a Middleware is the DEFAULT EXPORT of a module referenced from `middleware.use` by path (e.g. './app/middleware/auth.ts'). The generated server entry imports the module, so the middleware may close over module scope and import local helpers and third-party packages — it is a real module in the server module graph, never serialized source.

Custom Element base class for the compiled Part Program architecture. Subclasses are produced by the compiler; hand-written subclasses that never pass through the compiler fail closed at connect time.

One documented attribute of a custom element declaration.

name: string (必填); type?: string (可选); default?: string (可选); description?: string (可选); reflects?: boolean (可选); fieldName?: string (可选)

One documented CSS part of a custom element declaration.

name: string (必填); description?: string (可选)

One custom element declaration in a package manifest: tag, members and delivery metadata.

tagName: string (必填); className?: string (可选); superclassName?: string (可选); attributes?: OpenElementAttribute[] (可选); events?: OpenElementEvent[] (可选); slots?: OpenElementSlot[] (可选); cssParts?: OpenElementCssPart[] (可选); openElement.ssr?: boolean (可选); openElement.dsd?: boolean (可选); openElement.layer?: ComponentLayer (可选); openElement.hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); openElement.status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; openElement.module?: string (可选); openElement.export?: string (可选); description?: string (可选)

Framework error carrying a stable code, severity, phase and recoverability contract.

One documented custom event of a custom element declaration.

name: string (必填); type?: string (可选); description?: string (可选)

Package manifest of component declarations (not a Custom Elements Manifest).

schemaVersion: string (必填); packageName: string (必填); version: string (必填); description?: string (可选); author?: string (可选); license?: string (可选); homepage?: string (可选); repository?: string (可选); declarations: OpenElementDeclaration[] (必填)

Host-agnostic route and asset contracts shared by app and build drivers.

One node of the host-agnostic route tree: the matched URL `path` and route kind, the source and module paths the drivers resolve, the optional registered tag and param names, and the nested `children`.

kind: OpenElementRouteKind (必填); path: string (必填); filePath?: string (可选); importPath?: string (可选); tagName?: string (可选); paramNames?: string[] (可选); children?: OpenElementRouteNode[] (可选); meta?: Record<string, unknown> (可选)

One documented slot of a custom element declaration.

name: string (必填); description?: string (可选)

Media type of the RFC 9457 action error channel (#863).

RFC 9457 Problem Details document (#863): the action error channel answers `application/problem+json` instead of the bespoke `{ type: 'error', error: { message } }` JSON, so HTTP tooling recognizes failures natively. With `type: 'about:blank'`, `title` is the HTTP reason phrase and `detail` carries the specific explanation. The wire shape is alpha-unfrozen; the 1.0 acceptance freezes it in this problem+json form.

type: string (必填) — URI reference identifying the problem type; 'about:blank' when none applies.; title: string (必填) — Short human-readable summary (the HTTP reason phrase for 'about:blank').; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; detail?: string (可选) — Human-readable explanation specific to this occurrence.

Compiler-recognized property decorator; inert no-op at runtime.

reflect: boolean (必填); attribute?: string | false (可选); type?: unknown (可选); converter?: unknown (可选)

Provide a plain protocol value; the provider Signal remains OE-private.

Read-only signal protocol used by computed values.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@5309.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Server-render one compiled element through canonical Element composition.

Options for one `renderDsd()` call: the compiled component class to serialize, the values projected onto its compiled properties, optional route/source diagnostics metadata, the nested compiled tags the build admitted, and trusted parent-owned light children keyed by slot name.

componentClass?: CustomElementConstructor (可选); props?: Record<string, unknown> (可选); sourceInfo.route?: string (可选); sourceInfo.source?: string (可选); ssrRenderableTags?: readonly string[] (可选) — Build-admitted nested compiled tags. Omitted means shell-only rendering.; projectedChildren?: ReadonlyMap<string, TrustedHtml> (可选) — Trusted parent-owned light children keyed by slot name.

Recoverable render-phase error carrying the failing component path and tag.

The public result of one `renderDsd()` call: the serialized DSD `html`, the render errors collected while composing it (empty on success), the render metrics for the root component, and the hydration hints the client scheduler reads to upgrade islands.

html: string (必填); errors: RenderError[] (必填); metrics: DsdRenderMetrics (必填); hydrationHints: HydrationHint[] (必填)

Report an {@linkcode OpenElementError} to the telemetry hook, or console.error when none is installed.

code: string (必填); severity: ErrorSeverity (必填); phase: ErrorPhase (必填); recoverable: boolean (必填); statusCode.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; statusCode.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; statusCode.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; statusCode.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; statusCode.valueOf: () => number (必填) — Returns the primitive value of the specified object.; statusCode.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; toJSON: () => Record<string, unknown> (必填); name: string (必填); message: string (必填); stack?: string (可选); cause?: unknown (可选)

One route admitted by the scanner: URL `path`, source `filePath`, the route `type`, the generated variable name (`varName`) the entry binds it to, and the optional registration tag. {@link RouteEntry.definePage} and {@link RouteEntry.hasEnhancedForms} carry the two source-derived admission facts the generated entries branch on.

path: string (必填); filePath: string (必填); type: "page" | "api" | "island" | "special" (必填); varName: string (必填); tagName?: string (可选); definePage?: boolean (可选) — True when the route module's default export is a definePage() definition (#960 — registration decoupling). The generated entry registers the page class under the path-derived fallback tag and IGNORES the tagName export for registration: on a definePage route the export only names a content element. Plain element routes keep tagName as their registration tag.; source?: string (可选) — Source text captured during scanning when includeSource is enabled.; hasEnhancedForms?: boolean (可选) — True when the page route source carries data-open-enhance (#569): the client entry must ship the form-enhancement layer even when the app has zero islands.; special?: SpecialFileType (可选); params?: string[] (可选)

Canonical request-time/SSG server route context.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Context passed to a request-time ('dynamic') route loader. This is the server contract: the loader runs on the server with the Web-standard request, matched route params, the host environment and the platform object, and signals validation failure via fail()/redirect().

path: string (必填); filePath: string (必填)

Install the process-wide error telemetry hook (replaceable for tests, HMR, multi-app pages).

Create a writable signal through the selected signal engine.

Alias for APIs that accept either writable or read-only signals.

Special file kinds the route scanner recognizes by filename: `renderer` and `middleware`.

The build's admission verdict for one discovered tag: where the declaration lives (`modulePath`), how it was discovered (`source`), which render path it is admitted to, and the reason recorded for the manifest.

tagName: string (必填); modulePath: string (必填) — Module path of the island declaration. Empty for 'foreign' decisions: a foreign tag is consumed in JSX but declares no module the build owns.; source: "local" | "package" | "nested" | "foreign" (必填) — 'foreign' (#979): a third-party WC tag discovered by the foreign-tag scanner in page/island JSX — recorded for visibility only; SSR still treats it as an opaque passthrough (renderPath 'client-only').; renderPath: "ssr+client" | "client-only" | "rejected" (必填); reason: string (必填)

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Cross-realm StyleSheet constructor: the native CSSStyleSheet or the internal shim.

Minimal stylesheet contract (replaceSync + cssRules) satisfied by native and shim sheets.

replaceSync: (text: string) => void (必填); cssRules: StyleSheetRule[] (必填)

Mark an HTML string as trusted for explicit `innerHTML` sinks (the trust does not serialize).

Opaque capability marking HTML the application has explicitly vetted as trusted.

html: string (必填)

Whether a static attribute (name/value as authored into the Part Program) makes a streamed frame unsafely installable: event-handler, seed-spoofing, and srcdoc names fail outright, and URL-carrying names fail when the entity-decoded, control-stripped value carries a script scheme.

Wrap rendered HTML in a full HTML document. Adds DOCTYPE, head (title, meta, preload), and body. Supports CSP nonce and dev scripts (e.g. Vite client, route module registration).

Compose a fetch middleware chain (#858) around a handler, in onion order: `middleware[0]` is outermost — it sees the request first and the response last. A middleware may short-circuit by returning a Response without calling `next()`. Extra arguments (runtime context such as env/platform) thread transparently past the middleware chain to the terminal handler — the WinterCG-shaped middleware itself only ever sees `(request, next)`. Generated server entries call this once at module scope so the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry all share the same composed handler.

Normalize a runtime adapter declaration: pass the name, fetch handler and optional prerender iterator through unchanged so a host integration only implements the {@link RuntimeAdapter} contract it needs.

name: string (必填); fetch: OpenElementRequestHandler<Env> (必填); prerender?: (() => AsyncIterable<RuntimePrerenderResult> | Iterable<RuntimePrerenderResult>) (可选)

Serialize a value to pretty-printed JSON ending with a newline.

Insert markup before a tolerant HTML body close (`</body >`, case-insensitive).

Normalize path separators and collapse duplicates. - Backslashes and forward slashes are replaced with the chosen separator. - Repeated separators are collapsed to a single separator.

The host-neutral request handler every runtime adapter and generated server entry exposes: a WinterCG `(request, context?) => Response` with no server engine dialect baked in.

Convert a file path into a kebab-cased custom element tag name. - Removes a leading `./` or `/`. - Strips known file extensions (`ts`, `tsx`, `js`, `jsx`, `mjs`, `mdx`). - Replaces directory separators with hyphens. - Ensures the result starts with a letter and contains at least one hyphen.

runtime.ts - Runtime adapter protocol. Replacement boundary for Nitro, Workers, Node, Deno, or future fetch-compatible runtimes. Preserves openElement semantics while leaving concrete server engines outside this package.

env?: Env (可选); platform?: unknown (可选); params?: Record<string, string> (可选)

Thrown by the SSG build pipeline when the SSR bundle fails to load or the pipeline throws; re-exported via `@openelement/element/build-utils`. Carries the failing component path plus the original error as `cause`.

Inject island metadata markers into source code. Only transforms files inside the islands directory. Tag names are derived from the file path and normalized to valid custom element names (lowercase letters, digits, and hyphens). Unsafe characters are silently normalized to hyphens.

Route action: handles form submissions for a page route.

Request header selecting the action response channel: `true` marks a programmatic caller and selects the serialized ActionResult union; `enhance` marks the built-in morph enhancement and selects the same full-HTML responses the no-JS path receives.

Context passed to a route action function (extends loader context).

formData: FormData (必填); request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Wire shape returned to the JavaScript form-enhancement path. The no-JS path never sees this: it gets the equivalent semantics as plain HTTP (303 on success, 422 with the re-rendered form on validation failure, redirect/error as status codes). Success carries no data envelope. The application-loop contract makes a successful non-GET action answer 303 (PRG) — the framework never answers 200 with a rendered page, or with a success document, for a successful mutation — so the fetch channel answers `{ type: 'redirect' }` naming the PRG target and the authored return value is discarded by design. Success data travels the PRG target instead (query state the loader re-runs with, which the props projector then maps; see the router guide's "Form actions" section). The union previously declared a `{ type: 'success' }` member that no code path ever emitted — removed so the type matches the wire. Error outcomes (CSRF 403, unknown action 404, unparseable body 400, unexpected 500) are NOT part of this union: since #863 they answer RFC 9457 Problem Details with the PROBLEM_JSON_MEDIA_TYPE content type — see ProblemDetails.

Application shell declaration: `false` disables the shell entirely, `'default'` uses the built-in shell, and the object form names a tag with the module path that defines it (`import`, resolved like a {@link FrameworkOptions.middleware.use } entry) plus the compiled shell properties the router injects per route.

Assert that a tag name is a valid custom element name.

Collect all public (non-internal) own properties from a host object. Keys starting with `__openElement` are framework-internal and excluded. Uses Reflect.get for safe access (respects getters); a getter that throws is skipped with a warning so one bad prop cannot take the tree down.

The per-tag verdict the compatibility scanner records: the tier a discovered tag was classified as, the human-readable `reason`, where the tag was found (`source`), and the SSR/DSD/hydration facts the verdict was derived from.

tagName: string (必填); tier: CompatibilityTier (必填); reason: string (必填); source: "local" | "package" | "nested" (必填); modulePath?: string (可选); ssr?: boolean (可选); dsd?: boolean (可选); hydrate?: string (可选)

How far a discovered tag may participate in the build: 'ssr-capable' renders and hydrates, 'client-only' ships to the browser without server output, 'experimental-dom' is admitted with a downgraded guarantee, and 'rejected' fails the build.

The delivery layer a component belongs to: fully static DSD markup ('dsd-static'), DSD markup with a client island ('dsd-interactive'), a client-only island with no SSR output ('pure-island'), or a light-DOM element ('light-dom'). Recorded per component in the build manifest and consumed by the hydration scheduler.

Create a derived read-only signal recomputed from its dependencies.

Consumer-local reactive projection of a protocol context value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@6383: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@6385: string (必填); defaultValue: T (必填)

A typed context token: protocol identity (`key`) plus its default value.

key.toString: () => string (必填) — Returns a string representation of an object.; key.valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; key.description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; key.__@toPrimitive@6383: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; key.__@toStringTag@6385: string (必填); defaultValue: T (必填)

Create a typed context token shared between provider and consumer elements.

toString: () => string (必填) — Returns a string representation of an object.; valueOf: () => symbol (必填) — Returns the primitive value of the specified object.; description: string (必填) — Expose the [[Description]] internal slot of a symbol directly.; __@toPrimitive@6383: (hint: string) => symbol (必填) — Converts a Symbol object to a symbol.; __@toStringTag@6385: string (必填)

Create one request-local deferred shell from a generated route manifest. The manifest hash is checked against the exact runtime wire program before any shell can be produced.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Inputs for a request-scoped deferred DSD server executor.

componentClass: CustomElementConstructor (必填); props?: Record<string, unknown> (可选); manifest: DeferredDsdManifest (必填); instanceId: string (必填); documentToken?: string (可选)

Create a {@link Logger} that prefixes every message with `[tag]`.

Object prototype keys that must never be injected from untrusted props.

Resolve `id` (a `#hash` or bare id) against `root` and, when the id is not in that root's own tree, recurse into every nested shadow root. Returns the first match or `null`; a malformed percent-encoded id is not an error.

Initial shell, typed seed, and bounded updates for a deferred DSD request.

shell: string (必填); owner: DeferredServerOwner (必填); seed: Record<string, { state: "resolved"; type: string; value: unknown; } | { state: "pending"; type: string; } | { state: "missing"; type: string; }> (必填); resolvedValue: (field: string, value: unknown) => unknown (必填); serializeResolved: (field: string, value: unknown) => string[] (必填)

Maps route-local deferred fields to the compiled Part or Region owners they update.

program: { version: number; tag: string; sha256: string; } (必填); fields: readonly { field: string; signal: string; owners: readonly { kind: "part" | "region"; index: number; }[]; }[] (必填)

The same document serialization boundary, with only body wrappers left open.

title?: string (可选); lang?: string (可选); clientScript?: string (可选); scripts?: DocumentScriptDescriptor[] (可选); meta.description?: string (可选); meta.tags?: Record<string, string | number | boolean>[] (可选); devScripts?: string (可选); headExtras?: string (可选); dangerouslyHeadFragments?: string[] (可选); allowHeadExtrasScripts?: boolean (可选); links?: { rel: string; href: string; hreflang?: string; }[] (可选); structuredData?: readonly Record<string, unknown>[] (可选); cspNonce?: string (可选); streamBootstrap?: string (可选) — Trusted framework bootstrap emitted synchronously in the document head.

Run a side effect that re-subscribes whenever its signal dependencies change.

Compiler-recognized element decorator; inert no-op at runtime.

Install (once per document) framework-level fragment navigation: a same-document anchor click whose target lives inside a nested shadow root scrolls to it and pushes the hash instead of being dropped by the browser. `{ enabled: false }` opts an application out.

enabled?: boolean (可选) — Set false before installation to opt out for an application.

Install the bounded pre-upgrade interaction capture on an owning root (default: the document). Generated client entries call this with their declared island tags before any compiled element upgrades; after a successful claim the element replays the captured events whose targets live inside its root (compiled claim capture/replay, internal/compiled/runtime.ts). Idempotent per root (repeat calls merge tags, never reinstall listeners) and a no-op where no DOM exists (SSR). Invariant: the capture itself — one fixed listener set per owning root, installed once per page — is page-lifetime by design and is NOT the leak. The M1 leak was retained event-target records; each element releases exactly its own records at its activation decision (success or failure), while records owned by still-pending elements survive for their delayed/lazy upgrade (#1170). Boundedness: the facade capture passes the declared-island filter, so only interactions under a still-pending DECLARED island tag enter the queue — ordinary events and undeclared third-party custom elements are skipped (nested pending declared islands still capture through their own unsettled host). With no tags declared the legacy dash heuristic applies. The shared queue carries a hard capacity cap (fail closed), detached records are swept when a claim root adopts its share (and under queue pressure), and each activation decision deterministically empties that root's own bucket, so post-hydration traffic and removals never grow retention.

addEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: AddEventListenerOptions | boolean) => void (必填) — The **`addEventListener()`** method of the EventTarget interface sets up a function that will be called whenever the specified event is delivered to the target. [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/addEventListener); dispatchEvent: (event: Event) => boolean (必填) — The **`dispatchEvent()`** method of the EventTarget sends an Event to the object, (synchronously) invoking the affected event listeners in the appropriate order. The normal event processing rules (including the capturing and optional bubbling phase) also apply to events dispatched manually with dispatchEvent(). [MDN Reference](https://developer.mozilla.org/docs/Web/API/EventTarget/dispatchEvent); removeEventListener: (type: string, callback: EventListenerOrEventListenerObject | null, options?: EventListenerOptions | boolean) => void (必填) — The **`removeEventListener()`** method of the EventTarget interface removes an event listener previously registered with EventTarget.addEventListener() from the target. The event listener to be removed is identified using a combination of the event type, the event listener function itself, and various optional options that may affect the matching process; see Matching event listeners for removal.…

Error message prefix for all openElement errors.

Base class for elements that catch descendant render/hydration errors and apply a retry policy.

Callback receiving every reported {@linkcode OpenElementError} for telemetry.

Escape an HTML attribute value. Delegates to `escapeHtml` so both share the single `ESCAPE_MAP` and the same single-pass replacement (consolidated in #633). Empty-value conventions remain intentionally distinct by design: - `escapeHtml` returns '' for non-string input. - `escapeAttrValue` (below) coerces via `String()` and is the boundary meant for unknown/variable attribute values.

Escape the five HTML-significant characters in text content.

Format an unknown thrown value as a human-readable string.

The adapter-facing framework options: where routes, islands and components live, which renderer serializes pages, the application shell and layout declarations, the document `<html>`/head injection channels, and the request-time middleware switches. Every field is optional; the adapter applies its documented default. This is the type an application config file's default export is checked against, so the rendered option table and the actual config surface cannot drift.

renderer?: "native" | "lit" (可选) — Page renderer selection (Beta.2.2, #1339). EXPLICIT, never inferred: 'native' (default) renders pages through the compiled Part Program serializer (renderDsd); 'lit' renders LitElement pages through; routesDir?: string (可选) — Directory the route scanner walks, relative to the Vite root. Defaults to `app/routes`.; islandsDir?: string (可选) — Directory island modules are discovered in. Defaults to `app/islands`.; componentsDir?: string (可选) — Directory non-route components live in. Defaults to `app/components`.; packageIslands?: string[] (可选) — Extra package names whose island modules the build admits, e.g. `['@openelement/ui']`.; appShell?: AppShellConfig (可选) — Application shell declaration; `false` disables the shell, `'default'` uses the built-in one.; layouts?: LayoutsConfig (可选) — Per-layout shell declarations keyed by layout name.; mode?: "ssg" (可选) — Build mode. 'ssg' (default) generates static HTML.; headExtras?: string (可选) — @dangerous injected as-is, only use with controlled content; html.lang?: string (可选); html.title?: string (可选); inject.stylesheets?: (string | { href: string; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<string, string | number | boolean>; })[] (可选) — Stylesheets linked into the document head; each entry is an href or a link record with integrity/crossorigin/attrs.; inject.scripts?: (string | { src: string; type?: string; async?: boolean; defer?: boolean; integrity?: string; crossorigin?: "anonymous" | "use-credentials"; attrs?: Record<str… (可选) — Scripts emitted into the document; each entry is a src or a script record with type/async/defer/integrity/crossorigin/attrs.; inject.headFragments?: string[] (可选) — @dangerous fragments injected as-is. Trust boundary (same level as `trustedHtml`): never concatenate user-controlled content into these fragments; sanitize untrusted data at your own system boundary first. The framework only enforces no-`<script>` and no-executable-`<style>`.; ssr.noExternal?: (string | RegExp)[] (可选); island.upgradeStrategy?: "load" | "idle" | "visible" | "only" | "none" (可选); build.outDir?: string (可选) — Output directory for the build artifacts. Defaults to `dist`.; build.manifestBudget?: { islandKB?: number; totalJsKB?: number; pageKB?: number; } (可选) — Advisory only: exceeded budgets print build-manifest warnings and never fail the build; enforce them in your own build-output test.; viewTransition?: boolean (可选) — Enable the View Transitions API for client navigations. Defaults to true.; speculation?: boolean | { prerender?: string[]; prefetch?: string[]; exclude?: string[]; eagerness?: "immediate" | "moderate" | "conservative"; } (可选) — Speculation Rules emission: `true` uses framework defaults, or pass prerender/prefetch URL lists, exclusions and an eagerness.; middleware.cors?: boolean (可选) — Enable the built-in CORS middleware.; middleware.corsOrigin?: string | string[] (可选) — Static CORS allowlist data, serialized into the generated entry as JSON. Mutually exclusive with {@link FrameworkOptions.middleware.corsOriginModule }.; middleware.corsOriginModule?: string (可选) — Path to a module that default-exports `(origin: string) => string | undefined`. The generated entry imports the module — the callback is never serialized — so it may close over module scope and import dependencies. Resolved with the same idiom as `appShell.import` (e.g. './app/cors-origin.ts'). Mutually exclusive with `corsOrigin`.; middleware.requestId?: boolean (可选) — Emit and honor a per-request id header.; middleware.logger?: boolean (可选) — Log each request through the built-in logger.; middleware.securityHeaders?: boolean (可选) — Attach the built-in security response headers.; middleware.csp?: { policy?: string; nonce?: boolean; reportOnly?: boolean; } (可选) — Content-Security-Policy emission: the policy string, nonce generation, and report-only mode.; middleware.use?: string[] (可选) — Fetch middleware chain (#858), composed around the framework handler in onion order (`use[0]` outermost), outside all built-in middleware above. Each entry is a MODULE PATH (same resolution idiom as `appShell.import`, e.g. './app/middleware/auth.ts') whose default export is a {@link Middleware}; the generated entry emits `import * as __mw_N from '<path>'` and composes `__mw_N.default` in configur…

Runtime list of supported hydration strategies; the single source of truth for the `HydrationStrategy` union. Consumed by island/registry validation and re-exported from the element root for app and build adapters.

Island hydration trigger: 'load' | 'idle' | 'visible' | 'only'.

Idle-hydration scheduling fallback (milliseconds) when neither `requestIdleCallback` nor `requestAnimationFrame` is available.

Safely assign caller-supplied props onto a target object, skipping keys that could enable prototype pollution and tolerating read-only properties. The canonical guarded assigner for the canonical dangerous-key rule (#903, #1214): the

Shared dangerous-key predicate (#903, #1214). Prototype-internal keys must never be injected from untrusted props on ANY path: host prop collection (collectPublicProps / normalizePublicProps in props-utils.ts), guarded assignment (injectPropsSafe below — the SPA bootstrap page-projection write boundary in

Per-island delivery options (hydration strategy, SSR/DSD participation).

hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选) — Hydration strategy: - 'load': load immediately when module is imported - 'idle': defer to requestIdleCallback (default) - 'visible': use IntersectionObserver to defer until element is visible - 'only': client-only render, no DSD/SSR output Named `hydrate` to match `defineIslandConfig()` in the Router package — one option name across both packages.; dsd?: boolean (可选) — Whether to use DSD for SSR rendering of this island. Honored by the build-side island scan (via `defineIslandConfig`), not by `defineIsland()` itself: passing it in `IslandOptions` has no runtime effect.; ssr?: boolean (可选) — Whether this island may be admitted into server rendering. Like `dsd`, decided by the build-side island scan; inert when passed to `defineIsland()`.

Shared safe-attribute-name predicate (#1033): the SSR face of the one canonical predicate in `../protocol/forbidden-sinks.ts`. A name must be valid HTML attribute-name grammar (blocks quote/space injection, #602), must not be an event handler (`on*`, case-insensitive), and must not be a forbidden sink (`innerhtml`/`srcdoc`). The compiler, protocol validator, and server serializer enforce the same predicate with their own failure strategies; every path delegates to the single implementation, so the boundary cannot diverge.

Check if a tag name is a valid custom element name per HTML spec.

Route loader: fetches data for a page route.

Context passed to a request-time ('dynamic') route loader.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Locale-aware resolved path contract.

locale: string (必填); path: string (必填); localizedPath: string (必填); isDefaultLocalePath: boolean (必填)

logger.ts - Tagged console logger. Lightweight scoped logger. Returns plain functions so it is tree-shakable and has zero class overhead.

debug: (msg: string, ...args: unknown[]) => void (必填); info: (msg: string, ...args: unknown[]) => void (必填); warn: (msg: string, ...args: unknown[]) => void (必填); error: (msg: string, ...args: unknown[]) => void (必填)

Request-body bound (bytes) the generated entry applies to action POST routes; larger uploads belong on API routes with explicit limits.

Nested element expansion depth bound for `renderDsd`: cyclic component composition fails closed instead of recursing without end.

Fetch middleware contract (#858): WinterCG shape, dialect-free — no Hono/h3 context object. Composed at the handler boundary in onion order (`use[0]` is outermost: it sees the request first and the response last), so it runs with identical semantics in the dev server, the `start` CLI, the e2e fixture server, and the Nitro production entry. A middleware may short-circuit by returning a Response without calling `next()`, or post-process the Response that `next()` returns. Module contract: a Middleware is the DEFAULT EXPORT of a module referenced from `middleware.use` by path (e.g. './app/middleware/auth.ts'). The generated server entry imports the module, so the middleware may close over module scope and import local helpers and third-party packages — it is a real module in the server module graph, never serialized source.

Custom Element base class for the compiled Part Program architecture. Subclasses are produced by the compiler; hand-written subclasses that never pass through the compiler fail closed at connect time.

One documented attribute of a custom element declaration.

name: string (必填); type?: string (可选); default?: string (可选); description?: string (可选); reflects?: boolean (可选); fieldName?: string (可选)

One documented CSS part of a custom element declaration.

name: string (必填); description?: string (可选)

One custom element declaration in a package manifest: tag, members and delivery metadata.

tagName: string (必填); className?: string (可选); superclassName?: string (可选); attributes?: OpenElementAttribute[] (可选); events?: OpenElementEvent[] (可选); slots?: OpenElementSlot[] (可选); cssParts?: OpenElementCssPart[] (可选); openElement.ssr?: boolean (可选); openElement.dsd?: boolean (可选); openElement.layer?: ComponentLayer (可选); openElement.hydrate?: "load" | "idle" | "visible" | "only" | "none" (可选); openElement.status?: "stable" | "experimental" (可选) — Stability marker from the owning package's manifest policy.; openElement.module?: string (可选); openElement.export?: string (可选); description?: string (可选)

Framework error carrying a stable code, severity, phase and recoverability contract.

One documented custom event of a custom element declaration.

name: string (必填); type?: string (可选); description?: string (可选)

Package manifest of component declarations (not a Custom Elements Manifest).

schemaVersion: string (必填); packageName: string (必填); version: string (必填); description?: string (可选); author?: string (可选); license?: string (可选); homepage?: string (可选); repository?: string (可选); declarations: OpenElementDeclaration[] (必填)

Host-agnostic route and asset contracts shared by app and build drivers.

One node of the host-agnostic route tree: the matched URL `path` and route kind, the source and module paths the drivers resolve, the optional registered tag and param names, and the nested `children`.

kind: OpenElementRouteKind (必填); path: string (必填); filePath?: string (可选); importPath?: string (可选); tagName?: string (可选); paramNames?: string[] (可选); children?: OpenElementRouteNode[] (可选); meta?: Record<string, unknown> (可选)

One documented slot of a custom element declaration.

name: string (必填); description?: string (可选)

Media type of the RFC 9457 action error channel (#863).

RFC 9457 Problem Details document (#863): the action error channel answers `application/problem+json` instead of the bespoke `{ type: 'error', error: { message } }` JSON, so HTTP tooling recognizes failures natively. With `type: 'about:blank'`, `title` is the HTTP reason phrase and `detail` carries the specific explanation. The wire shape is alpha-unfrozen; the 1.0 acceptance freezes it in this problem+json form.

type: string (必填) — URI reference identifying the problem type; 'about:blank' when none applies.; title: string (必填) — Short human-readable summary (the HTTP reason phrase for 'about:blank').; status.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; status.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; status.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; status.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; status.valueOf: () => number (必填) — Returns the primitive value of the specified object.; status.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; detail?: string (可选) — Human-readable explanation specific to this occurrence.

Compiler-recognized property decorator; inert no-op at runtime.

reflect: boolean (必填); attribute?: string | false (可选); type?: unknown (可选); converter?: unknown (可选)

Provide a plain protocol value; the provider Signal remains OE-private.

Read-only signal protocol used by computed values.

value: T (必填); subscribe: (fn: (value: T) => void) => Unsubscribe (必填); __@SIGNAL_BRAND@6497.valueOf: () => boolean (必填) — Returns the primitive value of the specified object.

Server-render one compiled element through canonical Element composition.

Options for one `renderDsd()` call: the compiled component class to serialize, the values projected onto its compiled properties, optional route/source diagnostics metadata, the nested compiled tags the build admitted, and trusted parent-owned light children keyed by slot name.

componentClass?: CustomElementConstructor (可选); props?: Record<string, unknown> (可选); sourceInfo.route?: string (可选); sourceInfo.source?: string (可选); ssrRenderableTags?: readonly string[] (可选) — Build-admitted nested compiled tags. Omitted means shell-only rendering.; projectedChildren?: ReadonlyMap<string, TrustedHtml> (可选) — Trusted parent-owned light children keyed by slot name.

Recoverable render-phase error carrying the failing component path and tag.

The public result of one `renderDsd()` call: the serialized DSD `html`, the render errors collected while composing it (empty on success), the render metrics for the root component, and the hydration hints the client scheduler reads to upgrade islands.

html: string (必填); errors: RenderError[] (必填); metrics: DsdRenderMetrics (必填); hydrationHints: HydrationHint[] (必填)

Report an {@linkcode OpenElementError} to the telemetry hook, or console.error when none is installed.

code: string (必填); severity: ErrorSeverity (必填); phase: ErrorPhase (必填); recoverable: boolean (必填); statusCode.toString: (radix?: number) => string (必填) — Returns a string representation of an object.; statusCode.toFixed: (fractionDigits?: number) => string (必填) — Returns a string representing a number in fixed-point notation.; statusCode.toExponential: (fractionDigits?: number) => string (必填) — Returns a string containing a number represented in exponential notation.; statusCode.toPrecision: (precision?: number) => string (必填) — Returns a string containing a number represented either in exponential or fixed-point notation with a specified number of digits.; statusCode.valueOf: () => number (必填) — Returns the primitive value of the specified object.; statusCode.toLocaleString: { (locales?: string | string[], options?: Intl.NumberFormatOptions): string; (locales?: Intl.LocalesArgument, options?: Intl.NumberFormatOptions): string; } (必填) — Converts a number to a string by using the current or specified locale.; toJSON: () => Record<string, unknown> (必填); name: string (必填); message: string (必填); stack?: string (可选); cause?: unknown (可选)

One route admitted by the scanner: URL `path`, source `filePath`, the route `type`, the generated variable name (`varName`) the entry binds it to, and the optional registration tag. {@link RouteEntry.definePage} and {@link RouteEntry.hasEnhancedForms} carry the two source-derived admission facts the generated entries branch on.

path: string (必填); filePath: string (必填); type: "page" | "api" | "island" | "special" (必填); varName: string (必填); tagName?: string (可选); definePage?: boolean (可选) — True when the route module's default export is a definePage() definition (#960 — registration decoupling). The generated entry registers the page class under the path-derived fallback tag and IGNORES the tagName export for registration: on a definePage route the export only names a content element. Plain element routes keep tagName as their registration tag.; source?: string (可选) — Source text captured during scanning when includeSource is enabled.; hasEnhancedForms?: boolean (可选) — True when the page route source carries data-open-enhance (#569): the client entry must ship the form-enhancement layer even when the app has zero islands.; special?: SpecialFileType (可选); params?: string[] (可选)

Canonical request-time/SSG server route context.

request: Request (必填); params: Record<string, string> (必填); env: Env (必填); platform: Platform (必填); responseHeaders: Headers (必填) — Mutable response-only channel merged into the framework response.; route: Route (必填)

Context passed to a request-time ('dynamic') route loader. This is the server contract: the loader runs on the server with the Web-standard request, matched route params, the host environment and the platform object, and signals validation failure via fail()/redirect().

path: string (必填); filePath: string (必填)

Install the process-wide error telemetry hook (replaceable for tests, HMR, multi-app pages).

Create a writable signal through the selected signal engine.

Alias for APIs that accept either writable or read-only signals.

Special file kinds the route scanner recognizes by filename: `renderer` and `middleware`.

The build's admission verdict for one discovered tag: where the declaration lives (`modulePath`), how it was discovered (`source`), which render path it is admitted to, and the reason recorded for the manifest.

tagName: string (必填); modulePath: string (必填) — Module path of the island declaration. Empty for 'foreign' decisions: a foreign tag is consumed in JSX but declares no module the build owns.; source: "local" | "package" | "nested" | "foreign" (必填) — 'foreign' (#979): a third-party WC tag discovered by the foreign-tag scanner in page/island JSX — recorded for visibility only; SSR still treats it as an opaque passthrough (renderPath 'client-only').; renderPath: "ssr+client" | "client-only" | "rejected" (必填); reason: string (必填)

Tags a deferred frame cannot safely install into an owned Part range: the browser installer rejects any frame whose markup carries one of these.

Schemes that make a URL attribute unsafe in a streamed frame.

URL-carrying attributes the frame check screens for script-bearing scheme obfuscation; only these attribute names are value-screened.

Control characters at or below this code point are stripped before the URL-scheme test, so tab/newline/control obfuscation cannot smuggle a scheme past admission.

Deferred fields (declared streamed properties) one stream route's manifest may carry. The build scan, the server executor, and the browser seed contract enforce the same bound.

Part/Region owners one stream route's manifest may address in total across all deferred fields.

Serialized stream payload bound, as a string length in UTF-16 code units: one seed attribute or one deferred frame's markup may not exceed it. The server checks the JSON text and the rendered range before emitting; the browser checks the attribute before parsing.

Typed properties one streamed seed may carry: the browser seed contract rejects the WHOLE seed above this count, so an oversized component would silently fail to hydrate instead of failing loud at the server.

Deferred-field resolution budget (milliseconds) for one streamed response: fields still pending when it expires are failed in place and the stream ends with the shell and whatever resolved.

Cross-realm StyleSheet constructor: the native CSSStyleSheet or the internal shim.

Minimal stylesheet contract (replaceSync + cssRules) satisfied by native and shim sheets.

replaceSync: (text: string) => void (必填); cssRules: StyleSheetRule[] (必填)

Mark an HTML string as trusted for explicit `innerHTML` sinks (the trust does not serialize).

Opaque capability marking HTML the application has explicitly vetted as trusted.

html: string (必填)

Whether a static attribute (name/value as authored into the Part Program) makes a streamed frame unsafely installable: event-handler, seed-spoofing, and srcdoc names fail outright, and URL-carrying names fail when the entity-decoded, control-stripped value carries a script scheme.

Wrap rendered HTML in a full HTML document. Adds DOCTYPE, head (title, meta, preload), and body. Supports CSP nonce and dev scripts (e.g. Vite client, route module registration).

Escape an HTML attribute value. Delegates to `escapeHtml` so both share the single `ESCAPE_MAP` and the same single-pass replacement (consolidated in #633). Empty-value conventions remain intentionally distinct by design: - `escapeHtml` returns '' for non-string input. - `escapeAttrValue` (below) coerces via `String()` and is the boundary meant for unknown/variable attribute values.

Escape a string for use as an attribute value (double-quoted)

Escape the five HTML-significant characters in text content.

Branded type: a string that has been HTML-escaped (safe for text content)

Mark an HTML string as trusted for explicit `innerHTML` sinks (the trust does not serialize).

Opaque capability marking HTML the application has explicitly vetted as trusted.

html: string (必填)