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Jordan Ritter 4b4923561b feat: VS Code extension — Hook Explorer, AG-UI Inspector, webview-first sidebars (#3935)
## Summary

Three connected features land together so the CopilotKit VS Code
extension becomes a coherent debugger/preview surface:

1. **Hook Explorer** — every V1 + V2 render hook can be discovered and
previewed live with auto-generated controls, an inline `▶️ Preview
Component` CodeLens, and a sidebar that lists every captured site.
2. **AG-UI Event Inspector** — live SSE debug stream of all AG-UI
events, filterable and color-coded, in a sidebar view + editor panel.
3. **A2UI Catalog sidebar → webview** — the last native TreeView gets
replaced with a Tailwind-styled webview that matches the other two, now
with a proper **Go to source** action on components and fixtures.

## Hook Explorer

### Discovery + preview
- oxc-based scanner walks the workspace and finds every call-site of any
hook in the registry (17 across V1 + V2, render + data).
- Preview panel bundles the user's source via Rolldown (IIFE format,
React externalized, CSS collected per `@copilotkit/a2ui-renderer`
pattern), executes it in the webview with a capture-only **stub** for
`@copilotkit/react-core` (+ `/v2`), and mounts the user's component just
long enough to record each hook's config.
- Auto-generated form on the left/top drives the `render` prop's
args/parameters/state/event live. V1 parameter arrays and V2 Zod /
Standard Schema all map through a unified `FormSchema` derived at
runtime from the captured config.
- `useCopilotAction`, `useCopilotAuthenticatedAction_c`,
`useCoAgentStateRender`, `useLangGraphInterrupt`, `useRenderTool`,
`useRenderToolCall`, `useDefaultRenderTool`, `useLazyToolRenderer`,
`useRenderCustomMessages`, `useRenderActivityMessage`,
`useHumanInTheLoop`, `useInterrupt`, `useFrontendTool`, `useComponent`,
`useDefaultTool` all previewable.
- Inline `▶️ Preview Component` CodeLens above every render-hook call
site, backed by the same `copilotkit.hooks.preview` command as the
sidebar.
- Imported render components work: rolldown walks transitive imports
from the hook's `render` prop through any number of sibling files.
- Cross-file hook switches are robust: controls are reset on load,
Harness only mounts once the real HostRoot is ready, a top-level error
boundary auto-recovers when you pick a different hook.

### Why the stub approach
Bundling the real `@copilotkit/react-core` through rolldown's IIFE
output hit a `__commonJSMin` TDZ chain (`require_clipboard`,
`require_graphql`, `require_context_helpers`, …) because the
chat/runtime-client/markdown graph has circular imports. Externalizing
react-core + routing to a Proxy-backed stub that captures hook configs
avoids the whole CJS wrapping problem, shrinks the preview bundle from
~24 MB to ~1.3 KB, and keeps the preview runtime path completely
runnable without a live CopilotKit backend. Tradeoff documented in
`copilotkit-stubs.ts`.

### Weather-themed fixtures
14+ fixtures under `packages/vscode-extension/test-workspace/hooks`,
each a distinct visual scenario (forecast card, severity-palette alerts
with imported CSS, forecast strip, live radar grid, conic-gradient
precipitation gauge, air-quality badge with imported render, pollen
report with a 2-hop import graph, HITL evacuation confirm,
sunrise/sunset gradient, etc.). Used both as regression fixtures and as
the demo surface for video.

### Styling
- Tailwind-via-CDN + VS Code CSS variables for theme-aware chrome.
- User-provided CSS imports collected by rolldown and injected as a
`<style>` tag per load.
- Controls + form fields converted to Tailwind; textarea matches input
styling.
- Framed "Rendered output" card so the render prop is visually
unmistakable.

## AG-UI Event Inspector

### Runtime (`@copilotkit/runtime` + `@copilotkit/shared`)
- `DebugEventBus` — in-memory pub/sub on `BaseCopilotRuntime`, only
instantiated when `NODE_ENV != production`.
- Event tap in `createSseEventResponse` broadcasts every AG-UI event
with metadata (agentId, threadId, runId, timestamp).
- `GET /debug-events` SSE endpoint — returns 404 in production, streams
`DebugEventEnvelope` JSON to connected clients, initial `: connected`
comment flushes headers immediately.

### VSCode Extension
- `DebugStream` — Node SSE client with auto-reconnect, exponential
backoff, URL validation, error surfacing.
- `InspectorPanel` (editor panel, command `CopilotKit: Open AG-UI
Inspector`) and `InspectorViewProvider` (sidebar view) both use a shared
`DebugStream` instance — events persist when switching tabs.
- Inspector React app: `ConnectionBar`, `FilterBar`, `EventList`,
`EventDetail`.
- Color scheme: purple (lifecycle), red (errors), blue (text), orange
(tools), green (reasoning), teal (state), yellow (activity), gray
(unknown).

## A2UI Catalog → webview

- Replaces `ComponentPreviewProvider` (native TreeDataProvider) with
`CatalogListViewProvider` (WebviewViewProvider), matching the Hooks and
Inspector sidebars.
- New React webview with refresh header, component rows (name + relative
path + `auto` badge when no fixture), expandable fixtures list.
- Click a component row → preview (or toggle if it has fixtures); click
a fixture row → preview that fixture.
- Hover action buttons: `▷` preview + `</>` go-to-source on every row.
- "Go to source" opens the component file for component rows; for
fixture rows it opens the fixture file and jumps the cursor to the named
fixture key.

## Test coverage
- Runtime: DebugEventBus unit tests (8), handleDebugEvents endpoint (5),
fetch-router routes (4), integration across Express/Hono/Node/Fetch (9).
- Hooks: scanner + 16 fixture bundle-smoke test, regression guard
against `node_<builtin>` self-references, CSS collector test, stub-based
capture E2E, cross-kind controls remount, FormRenderer defensive
rendering.
- Inspector + webview: DebugStream reconnect (10), inspector components
(17), colors (9).
- Total: **178 tests** passing for the vscode-extension package; runtime
suite unchanged.

## Test plan

- [ ] `pnpm nx run copilotkit-vscode-extension:build` and `pnpm nx run
copilotkit-vscode-extension:test` both green
- [ ] F5 launches the Extension Dev Host with `test-workspace` open
- [ ] Hooks sidebar lists every fixture hook; click a row → preview
opens; `</>` button opens the source
- [ ] `▶️ Preview Component` CodeLens shows above every render hook in a
`.tsx` file; clicking it opens the preview
- [ ] Form controls drive the render live; cross-kind hook switches
(action ↔ custom-message) don't crash; a forced render-prop throw
recovers when a different hook is picked
- [ ] Imported-render fixtures (`ImportedAirQuality`,
`ImportedPollenReport`) bundle and preview correctly
- [ ] A2UI Catalog sidebar is the new webview, refresh works, `</>` on a
fixture opens the fixture file and reveals the named key
- [ ] AG-UI Inspector connects to `GET /debug-events`, filters + detail
work, events survive sidebar/panel switch, invalid URL shows red error
2026-04-21 17:09:45 -07:00
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