[RNE Rewrite] test(ts): add API tests for the TypeScript surface

.agents/skills/README.md

@@ -8,5 +8,6 @@ This directory contains specialized skills (recipes) to guide contributors and A
 - [Add Native Extension](./add-native-extension/SKILL.md) — C++ operations and JSI bindings.
 - [Add Task Pipeline](./add-task-pipeline/SKILL.md) — TypeScript task pipelines and React hooks.
 - [Model Schema Validation](./model-schema-validation/SKILL.md) — Model specs, dynamic shapes, and schema validation.
+- [Add API Tests](./add-api-tests/SKILL.md) — TypeScript API test suites and the fake native runtime.
 - [Verify and Build](./verify-and-build/SKILL.md) — TypeScript typechecking, native rebuilding, and troubleshooting.
 - [Skills Maintenance](./skills-maintenance/SKILL.md) — Keeping skills synchronized with core primitives.

.agents/skills/add-api-tests/SKILL.md

@@ -0,0 +1,136 @@
+---
+name: add-api-tests
+description: Use when adding or changing anything under src/ — a task pipeline, a hook, a native op wrapper, a registry entry — and you need to cover it with the TypeScript API test suites.
+metadata:
+  id: add_api_tests
+  scope: packages/react-native-executorch/__tests__/*
+---
+
+# Skill: Add TypeScript API Tests
+
+Every change under `src/` belongs in the Jest suites at
+[`packages/react-native-executorch/__tests__/`](../../../packages/react-native-executorch/__tests__/README.md).
+They run on a laptop or a CI runner — no simulator, no device, no `.pte` — and
+finish in a few seconds.
+
+```bash
+yarn workspace react-native-executorch test
+yarn workspace react-native-executorch test __tests__/tasks   # one directory
+yarn workspace react-native-executorch test -u                # update snapshots
+```
+
+Types come along for free: `yarn typecheck` already covers `__tests__/`.
+
+---
+
+## 🧩 The Fake Native Runtime
+
+There is no stubbing of individual JSI calls. `__tests__/support/fakeJsi.ts`
+implements the whole `__rnexecutorch_jsi__` contract in JavaScript — tensors
+hold real data, `math`/`cv`/`speech` operators compute real values — so a task
+pipeline runs end to end and its own logic is what the assertions measure.
+
+A test describes the model it wants, then drives the real pipeline:
+
+```typescript
+import { f32, method } from '../../src/core/schema';
+import { fakeJsi } from '../support/fakeJsi';
+import { tracked } from '../support/lifetime';
+import { STRETCH_PREPROCESSING, exported, imageBuffer, writesOutputs } from '../support/fixtures';
+
+fakeJsi.registerModel('/models/task.pte', {
+  schema: exported(method('forward', [f32(1, 3, 4, 4)], [f32(1, 3)])),
+  execute: writesOutputs([1, 0, 2]),
+});
+
+const runner = tracked(await createMyTask({ modelPath: '/models/task.pte', modelOpts }));
+expect(await runner.runTask(imageBuffer(8, 8))).toEqual(/* ... */);
+```
+
+Key helpers:
+
+| Helper | Use |
+| :--- | :--- |
+| `fakeJsi.registerModel(path, program)` | Make `loadModel(path)` succeed with a given schema and `execute` |
+| `fakeJsi.registerTokenizer(path, vocabulary)` | Same for `loadTokenizer` |
+| `exported(spec)` | Reinterpret a spec built with `method`/`f32`/`i64` as an *exported* one (it verifies no symbolic dims are left) |
+| `writesOutputs(...)`, `copiesInputToOutput()` | Ready-made `execute` implementations |
+| `tracked(pipeline)` | Auto-dispose at the end of the test |
+| `imageBuffer(w, h, format)` | A deterministic input image |
+| `cachePathFor(url)` | Where the fetcher will download a URL, so a hook test can register its model up front |
+| `fakeNet.serve(url, route)` | Script the server: status, body, `Range` support, and a `gate` to hold a download open |
+
+---
+
+## 🧠 What to Cover for a New Task Pipeline
+
+1. **Schema acceptance** — one test per variant the pipeline declares
+   (`batched`, `unbatched`, ...), asserting the factory resolves.
+2. **Schema rejection** — a model that matches no variant, asserting the error
+   names the mismatch (`Rank mismatch`, `inconsistent bindings`, ...). A caller
+   should learn what is wrong from the message.
+3. **Configuration mismatch** — e.g. a `labels` array that disagrees with the
+   model's output dimension.
+4. **Postprocessing** — the part that is yours: sorting, thresholding,
+   suppression, colormaps, coordinate scaling. Choose fixture values that make
+   the expected output obvious in the test.
+5. **Options** — every default in `modelOpts`, and every per-call override.
+6. **Disposal** — `dispose()` leaves `fakeJsi.liveTensors()` at 0 and
+   `fakeJsi.liveModels()` empty, and repeated calls do not accumulate scratch
+   tensors.
+7. **Sync/async parity** — `runTaskWorklet(x)` equals `await runTask(x)`.
+
+For a new hook, add a case to `__tests__/hooks/`: not-ready before the download
+lands, methods exposed after, errors surfaced through the shared `error` field,
+and every native handle released on unmount.
+
+---
+
+## 🔒 Leak Checking
+
+Native memory is not garbage collected, so the setup file asserts after **every
+test** that nothing allocated through the fake was left undisposed. That gives
+each pipeline suite disposal coverage for free.
+
+- Wrap construction in `tracked()` — it disposes at the end of the test and
+  stops a failing assertion from cascading into a second, misleading error.
+- A test that deliberately leaks calls `allowNativeLeaks()` with a comment
+  saying why.
+
+---
+
+## 📐 Source-Level Conventions
+
+`__tests__/api/workletDirective.test.ts` parses `src/` with the TypeScript
+compiler and enforces the conventions no type can express:
+
+- every exported function that calls into `rnexecutorchJsi` starts with
+  `'worklet';`
+- no `async` function is marked as a worklet
+- only `src/native/bridge.ts` names the `__rnexecutorch_jsi__` global
+- `core/` never imports from `extensions/`, and `hooks/` never imports from
+  `native/`
+
+If you add a new native wrapper without the directive, that suite fails — add
+the directive rather than the exception.
+
+---
+
+## 📋 Verification Checklist
+
+When adding or changing code under `src/`, verify that:
+
+- [ ] `yarn workspace react-native-executorch test` passes.
+- [ ] A new task pipeline has a suite covering acceptance, rejection,
+      postprocessing, options and disposal.
+- [ ] A new hook has a lifecycle case in `__tests__/hooks/`.
+- [ ] A new registry entry passes `__tests__/api/modelRegistry.test.ts` without
+      the rules being loosened (https URL, pinned revision,
+      `modelname_backend_precision.pte`, backend-matching folder, default
+      aliasing one of its own variants).
+- [ ] A new export is reflected in the `api/apiSurface` snapshot, and the change
+      is intentional (a removal or rename is a breaking change).
+- [ ] Any new fake behaviour in `__tests__/support/` is faithful where fidelity
+      changes an assertion, and its simplifications are commented.
+- [ ] No test was made to pass by calling `allowNativeLeaks()` without an
+      explanation.

.agents/skills/add-task-pipeline/SKILL.md

@@ -188,28 +188,22 @@ Wrap the task pipeline in a custom React Hook using the core hooks `useResourceD
 
 ```typescript
 import { useModel } from './useModel';
-import { useResourceDownload } from './useResourceDownload';
+import { useResourceDownload, type ResourceOptions } from './useResourceDownload';
 import { createMyTask, type MyTaskModel } from '../extensions/<domain>/tasks/<task>';
 
-export function useMyTask(config: MyTaskModel, options?: { preventLoad?: boolean }) {
-  // 1. Resolve remote or local asset model path and download progress
-  const { localPath, downloadProgress, downloadError } = useResourceDownload(
-    config.modelPath,
-    options?.preventLoad
-  );
+export function useMyTask(config: MyTaskModel, options?: ResourceOptions) {
+  // 1. Resolve every remote URL in the config to a local path, with progress
+  //    weighted across all of them.
+  const { resource, downloadProgress, downloadError } = useResourceDownload(config, options);
 
   // 2. Instantiate and compile the task pipeline (with automatic lifecycle cleanup)
-  const { model, error } = useModel(
-    createMyTask,
-    localPath ? { ...config, modelPath: localPath } : null,
-    [localPath]
-  );
+  const { model, error } = useModel(createMyTask, resource ?? null);
 
   return {
     isReady: !!model,
     error: downloadError || error,
     downloadProgress,
-    localPath,
+    resource,
     runTask: model?.runTask,
     runTaskWorklet: model?.runTaskWorklet,
   };
@@ -233,3 +227,4 @@ When adding a task pipeline or React hook, verify that:
 - [ ] Every parameter is bucketed per Principle 6: varies across variants → option; fixed by the export → `const` in the task file; per-call choice → executor argument.
 - [ ] No exposed option has exactly one valid value, and no two `models.ts` variants pass an identical options object.
 - [ ] The React Hook utilizes `useModel` and properly returns progress, ready state, errors, and task execution bindings.
+- [ ] The pipeline has a suite under `__tests__/tasks/` covering schema acceptance and rejection, postprocessing, every option, and full disposal — see the [Add API Tests skill](../add-api-tests/SKILL.md).

.agents/skills/core-guidelines/SKILL.md

@@ -72,6 +72,7 @@ Use the following index to locate the specific procedural guides for your task:
 | **Add a new native operator or C++ binding** | [SKILL.md](../add-native-extension/SKILL.md)    | Procedural guide to implementing C++ functions, exposing them via JSI, and writing TypeScript bridge wrappers. |
 | **Create a task pipeline or hook**           | [SKILL.md](../add-task-pipeline/SKILL.md)       | Guide to building end-to-end TS pipelines (e.g. object detection) and exposing them via React hooks.           |
 | **Verify, rebuild, or troubleshoot changes** | [SKILL.md](../verify-and-build/SKILL.md)        | Workflows for rebuilding TS/C++ and resolving common JSI runtime errors.                                       |
+| **Test TypeScript changes**                  | [SKILL.md](../add-api-tests/SKILL.md)           | Covering `src/` with the Jest API suites and their fake native runtime.                                        |
 | **Validate model constraints & schemas**     | [SKILL.md](../model-schema-validation/SKILL.md) | Guide on specifying model specs, dynamic shapes, and runtime constraints for model validation.                 |
 | **Maintain or refactor codebase patterns**   | [SKILL.md](../skills-maintenance/SKILL.md)      | Guide to keeping workspace skills in sync with codebase state to prevent documentation decay.                  |
 

.agents/skills/skills-maintenance/SKILL.md

@@ -26,6 +26,7 @@ Use this guide when you introduce, modify, or deprecate core codebase patterns,
      - [add-task-pipeline](../add-task-pipeline/SKILL.md) for TypeScript pipeline orchestration, pre-allocation, and lifecycle hooks.
      - [model-schema-validation](../model-schema-validation/SKILL.md) for schema verification constraints.
      - [verify-and-build](../verify-and-build/SKILL.md) for compilation and troubleshooting steps.
+     - [add-api-tests](../add-api-tests/SKILL.md) for the TypeScript test suites and the fake native runtime.
 
 3. **Verify Example Correctness**:
    - Ensure all code blocks and examples in updated skills compile/work and match actual usage in the repository.

.agents/skills/verify-and-build/SKILL.md

@@ -22,6 +22,14 @@ To check types and compile the TypeScript source code:
   ```bash
   yarn typecheck
   ```
+- **Run the TypeScript API Tests**:
+  ```bash
+  yarn workspace react-native-executorch test
+  ```
+  _Jest suites over the public `src/` surface — hooks, task pipelines, core
+  primitives, the fetcher and the model registry — running against a fake
+  native runtime, so they need no simulator, device or `.pte` file. See the
+  [Add API Tests skill](../add-api-tests/SKILL.md)._
 - **Build Bundles**:
   ```bash
   yarn prepare
@@ -172,7 +180,7 @@ This project does **not** bundle local `.pte` model files inside the React Nativ
 
 ## 🚫 Avoid / Anti-Patterns
 
-- **Do NOT run code without verification:** Do not test TypeScript changes in the app without first running `yarn typecheck` (verify types) and `yarn prepare` (build target bundles).
+- **Do NOT run code without verification:** Do not test TypeScript changes in the app without first running `yarn typecheck` (verify types), `yarn workspace react-native-executorch test` (API suites) and `yarn prepare` (build target bundles).
 - **Do NOT skip native rebuilds after C++ edits:** If any C++ files or config bindings are added/modified, do not attempt to run the app without executing `pod install` (for iOS) or letting Gradle sync (for Android).
 - **Do NOT run `lint:cpp` with the system `clang-tidy`**: Use the Homebrew LLVM binary: `CLANG_TIDY=$(brew --prefix llvm)/bin/clang-tidy yarn workspace react-native-executorch lint:cpp`.
 - **Do NOT log complex objects inside worklets:** Avoid passing complex circular objects directly to `console.log()` inside functions annotated with `'worklet';` as it can hang or crash the worklet runtime thread.
@@ -185,6 +193,7 @@ This project does **not** bundle local `.pte` model files inside the React Nativ
 When verifying or compiling your modifications, check that:
 
 - [ ] TypeScript typechecking passes without errors (`yarn typecheck`).
+- [ ] The TypeScript API tests pass (`yarn workspace react-native-executorch test`), and any new `src/` behavior is covered by them.
 - [ ] Bundles compile successfully (`yarn prepare`).
 - [ ] `pod install` has been run inside `apps/<domain-app>/ios/` after any native C++ edits.
 - [ ] `lint:cpp` passes cleanly: `CLANG_TIDY=$(brew --prefix llvm)/bin/clang-tidy yarn workspace react-native-executorch lint:cpp`.

.cspell-wordlist.txt

@@ -314,3 +314,10 @@ Partitioner
 denoised
 ttfa
 TTFA
+letterboxed
+macrotask
+microtask
+microtasks
+unbatched
+sdcard
+dontMock

.eslintrc.js

@@ -79,6 +79,19 @@ module.exports = {
         'no-console': 'warn',
       },
     },
+    {
+      // The JSDoc rules exist to keep the generated API reference complete.
+      // Test helpers are not part of that surface, and requiring a tag per
+      // parameter on a three-line fixture crowds out the prose that explains
+      // why the fixture exists.
+      files: ['packages/react-native-executorch/__tests__/**/*.{ts,tsx}'],
+      rules: {
+        'jsdoc/require-param': 'off',
+        'jsdoc/require-param-description': 'off',
+        'jsdoc/require-returns': 'off',
+        'jsdoc/require-returns-description': 'off',
+      },
+    },
     {
       files: ['**/*.md'],
       processor: 'markdown/markdown',

.github/workflows/ci.yml

@@ -39,3 +39,21 @@ jobs:
 
       - name: Build all packages
         run: yarn workspaces foreach --all --exclude react-native-executorch-bare-resource-fetcher --exclude react-native-executorch-expo-resource-fetcher --exclude react-native-executorch-webrtc --topological-dev run prepare
+
+  api-tests:
+    name: TypeScript API tests
+    runs-on: ubuntu-latest
+    # A full run takes a few seconds; this only has to catch a hang.
+    timeout-minutes: 15
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+
+      - name: Setup
+        uses: ./.github/actions/setup
+
+      # No native libraries, no simulator, no `.pte` download — the suites run
+      # against the fake JSI runtime in `__tests__/support/`, so the setup
+      # action's TypeScript-only install is all this job needs.
+      - name: Run TypeScript API tests
+        run: yarn workspace react-native-executorch test --ci

packages/react-native-executorch/__tests__/README.md

@@ -0,0 +1,97 @@
+# TypeScript API tests
+
+Jest suites covering the public TypeScript surface under `src/` — the hooks,
+the task pipelines, the core primitives, the resource fetcher and the model
+registry. They run on a developer machine or a CI runner: no simulator, no
+emulator, no device, no `.pte` file, and the whole run finishes in a few
+seconds.
+
+```bash
+yarn workspace react-native-executorch test
+yarn workspace react-native-executorch test --watch
+yarn workspace react-native-executorch test __tests__/tasks   # one directory
+```
+
+Types are checked by the existing `yarn typecheck`, which already covers this
+directory.
+
+## Why a fake native runtime, not stubs
+
+Every path through `src/` bottoms out in `__rnexecutorch_jsi__`: a pipeline
+allocates tensors, hands them to `model.execute`, and pushes them through
+`softmax`, `resize` and `nms` on the way in and out. Stubbing those calls per
+test would mean each assertion checks the stub rather than the pipeline — the
+sorting in `classify`, the suppression in `detectObjects` and the colormap in
+`segment` would all go untested.
+
+So `support/fakeJsi.ts` implements the native contract in JavaScript instead:
+
+| Piece | What it does |
+| --- | --- |
+| `support/fakeTensor.ts` | Typed-array-backed tensors with the real `setData`/`getData` byte semantics, `copyTo` windows, and use-after-dispose errors |
+| `support/fakeOps.ts` | JS implementations of the `math`, `cv` and `speech` operators |
+| `support/fakeJsi.ts` | `createTensor`, `loadModel`, `loadTokenizer`, and the resource trackers |
+| `support/blobUtilMock.ts` | In-memory filesystem plus a programmable server (status, body, `Range` support, and a gate to hold a download open) |
+| `support/workletsMock.ts` | Runs worklets inline — a worklet is an ordinary function marked for a second runtime |
+
+A test describes the model it wants and drives the real pipeline over it:
+
+```ts
+fakeJsi.registerModel('/models/classifier.pte', {
+  schema: exported(method('forward', [f32(1, 3, 4, 4)], [f32(1, 3)])),
+  execute: writesOutputs([1, 0, 2]),
+});
+
+const classifier = tracked(await createClassifier(config));
+expect((await classifier.classify(imageBuffer(8, 8))).map((r) => r.label))
+  .toEqual(['bird', 'cat', 'dog']);
+```
+
+The fake is faithful where fidelity changes an assertion — writing a float into
+`uint8` storage rounds and clamps the way OpenCV's `saturate_cast` does, and the
+tokenizer's methods are closures rather than prototype methods because a real
+JSI host object's are — and deliberately simple elsewhere: `resize` is
+nearest-neighbor whatever interpolation is asked for, and models the geometry
+only. The numerical behavior of the real operators belongs to the C++ suites in
+[`cpp/tests/`](../cpp/tests/README.md); what these suites own is the TypeScript
+above them.
+
+## Leak checking
+
+Native memory is not garbage collected, so anything a test allocates through
+the fake and does not dispose is a leak in the code under test. The setup file
+asserts that after every test, so each pipeline suite gets disposal coverage
+for free.
+
+Wrap construction in `tracked()` and the harness disposes it at the end of the
+test — which also keeps a failing assertion from cascading into a second,
+misleading leak error. A test that means to leak calls `allowNativeLeaks()`.
+
+## Layout
+
+| Path | Contents |
+| --- | --- |
+| `core/` | `tensor`, `model`, `runtime`, and the `schema` spec matcher |
+| `fetcher/` | `download` (caching, resume, cancellation, shared requests), telemetry, the Android backend |
+| `tasks/` | One suite per task pipeline, plus the shared construction-failure behavior |
+| `hooks/` | `useModel`, `useResourceDownload`, and the task hooks end to end |
+| `extensions/` | The pure-TypeScript helpers: box/point scaling, seeded generators |
+| `api/` | Export snapshot, model registry rules, label constants, source-level conventions |
+| `support/` | The fake runtime, the mocks, and the fixtures |
+
+## What is deliberately not covered
+
+**Numerical behavior of the native operators.** `resize` interpolation,
+`cvtColor` conversions and the exact `nms` arithmetic are the C++ suites' job;
+duplicating them here would only test the fake.
+
+**The long stateful worklets.** Whisper's decode loop, the VAD rolling window
+and the SDXS diffusion step depend on real model weights, so faking them would
+mostly assert against the fixture. What they do get is schema acceptance,
+rejection of a mismatched model, and full disposal — including Whisper's nested
+tokenizer and VAD pipeline.
+
+**The thread hop.** Worklets run inline here, so serialization onto a real
+worklet runtime is not exercised. The `'worklet'` directive convention that
+makes that hop possible *is* checked, by parsing `src/` in
+`api/workletDirective.test.ts`.