G3: vendored hook schemas + CI drift detector (#947)

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## Summary

Implements **G3** from the hooks plan: vendored Claude SchemaStore +
Cursor community hook schemas; warn-level authoring lint only; CI drift
detector vs adapter-known events.

**Stacked on #946 (G2) → #945 (G1) → … → #913 (A1).**

## Acceptance criteria (from plan G3 row)

- Pin Claude SchemaStore + Cursor community schemas
- Warn-level authoring lint only, never a load gate, never
remote-fetched
- CI test diffs published event lists vs adapter-known events

## Deliverables

- `schemas/vendor/` with provenance README
- `vendor-schema-drift.test.ts`
- Claude unknown/unsupported event warnings (parity with Cursor)

## Tests

- `npm run check` green (2965 tests)

## Test plan

- [x] `npm run check`
- [ ] CI green

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---------

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: Jonathan Kingston <jonathanKingston@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: 3 people

.prettierignore

@@ -10,3 +10,6 @@ tests/e2e/electron-shell/.e2e-env.json
 tests/fixtures/git-changes-repo/
 # E2E markdown fixture with intentional hard-break trailing spaces +  .
 tests/fixtures/job-description-metadata.md
+# Vendored upstream hook schemas (G3) — pinned byte-identical to upstream; never
+# reformatted so the drift detector compares against exactly what was published.
+schemas/vendor/*.json

docs/cursor-hooks.md

@@ -246,6 +246,32 @@ This is the same trust boundary described in
 [`docs/supply-chain-security.md`](./supply-chain-security.md): trusting a workspace means
 trusting the code it can cause to run.
 
+## Vendored upstream schemas & drift detection (G3)
+
+Copse pins committed copies of the upstream hook-config JSON schemas for both
+foreign dialects under [`schemas/vendor/`](../schemas/vendor/) —
+`claude-code-settings.schema.json` (Claude Code, from SchemaStore) and
+`cursor-hooks.schema.json` (the community `cursor-hooks` npm schema). See
+[`schemas/vendor/README.md`](../schemas/vendor/README.md) for provenance, pins,
+and the re-vendoring steps.
+
+These exist for exactly two purposes, and are subject to two hard rules — they
+are **never fetched over the network** at runtime or in CI, and they are **never
+a load gate** (a config that violates an upstream schema still loads):
+
+1. **Warn-level authoring lint.** Parsing a foreign config uses the schema's
+   published event list to warn when a hooks group targets an event the vendor
+   recognises but Copse does not act on yet (vs an outright typo). The valid
+   hooks still load; the warning surfaces in Settings → Sources.
+2. **CI drift detector** (`src/main/services/hooks/vendor-schema-drift.test.ts`)
+   diffs each vendored schema's published events against the events our adapters
+   wire. Every published event must be either wired or listed in an explicit
+   intentionally-unsupported set (`src/shared/hooks/vendored-hook-schemas.ts`); an
+   upstream release adding an unaccounted event fails CI until it is wired or
+   documented. Copse currently wires Claude `PreToolUse` + `SessionStart` and the
+   Cursor events above; the long tail of Claude events (`Notification`,
+   `TeammateIdle`, …) is intentionally-unsupported v1.
+
 ## Gaps and future work
 
 1. **Content rewriting** — `updated_input` on tool gates (rewrite the proposed tool
@@ -272,6 +298,9 @@ trusting the code it can cause to run.
 - `src/main/services/security/permission-gate.ts` — calls the tool-gate hooks
 - `src/shared/types/cursor-hooks.ts` — `CursorHookEvent` / `CursorHookSummary`
 - `src/shared/types/hooks.ts` — shared `HookSummary` for Sources / `hooks:list`
+- `src/shared/hooks/vendored-hook-schemas.ts` — published-event mirrors + intentionally-unsupported sets (G3)
+- `schemas/vendor/` — pinned upstream Cursor + Claude hook schemas (G3); see its `README.md`
+- `src/main/services/hooks/vendor-schema-drift.test.ts` — CI drift detector (G3)
 - `src/main/services/exec/child-process-env.ts` — secret-scrubbed env for hook processes
 - `docs/claude-hooks.md` — Claude Code hooks contract
 - `docs/cursor-plugins.md` — sibling exploration of Cursor plugin support

docs/plans/hooks-and-feature-packs.md

@@ -0,0 +1,75 @@
+# Vendored upstream hook schemas (G3)
+
+Pinned, committed copies of the **upstream** hook-config JSON schemas for the two
+foreign dialects Copse imports (`.claude/settings.json` and `.cursor/hooks.json`).
+They exist for two reasons, and **only** two:
+
+1. **Warn-level authoring lint.** When Copse parses a foreign hooks config it uses
+   the _published event list_ from these schemas to tell an author "this event is
+   recognised upstream but Copse does not act on it yet" vs "this looks like a
+   typo". This is a **warn-only** lint surfaced in Settings → Sources — it is
+   **never a load gate**: every valid hook still loads, exactly as before.
+2. **CI drift detector.** `src/main/services/hooks/vendor-schema-drift.test.ts`
+   diffs the event list each vendored schema publishes against the events our
+   adapters actually wire, and fails CI when an upstream release adds an event we
+   neither support nor have explicitly listed as intentionally-unsupported. That
+   forces a deliberate choice (wire it, or document why not) instead of silent
+   drift.
+
+## Hard rules (do not break)
+
+- **Never remote-fetched.** Neither the runtime app nor CI fetches these at
+  runtime or test time — the drift detector reads the committed copies from disk
+  only. The network is used **exactly once**, by a human/agent re-vendoring a pin
+  (see below). Tests and the app must work fully offline.
+- **Never a load gate.** These schemas do not validate/reject a user's hooks
+  config. A config that violates an upstream schema still loads; at most it earns
+  a warning row. Copse's own `schemas/copse-hooks.schema.json` is the only schema
+  we author; these vendored ones are read-only references.
+- **Pinned, not tracked live.** We pin a specific upstream revision so the drift
+  detector is deterministic. Bumping a pin is an explicit, reviewed change.
+
+## Pins
+
+| File                               | Upstream                                                                   | Source URL                                                      | Pinned                                 | Retrieved  | sha256                                                             |
+| ---------------------------------- | -------------------------------------------------------------------------- | --------------------------------------------------------------- | -------------------------------------- | ---------- | ------------------------------------------------------------------ |
+| `claude-code-settings.schema.json` | Claude Code settings (SchemaStore)                                         | <https://www.schemastore.org/claude-code-settings.json>         | SchemaStore `last-modified` 2026-07-15 | 2026-07-16 | `2b4004b2af619ce16bd6dafc0a8f1f03974f45740f4212a1f85f236364057d28` |
+| `cursor-hooks.schema.json`         | `cursor-hooks` npm package (community, "Cursor Community" / johnlindquist) | <https://unpkg.com/cursor-hooks@1.1.5/schema/hooks.schema.json> | npm `cursor-hooks@1.1.5`               | 2026-07-16 | `824c8bbe802305827f813c19f2411b883afe8d02f0b947d7c30428f4effc18f3` |
+
+Notes on each pin:
+
+- **Claude — SchemaStore.** SchemaStore's `claude-code-settings.json` is the
+  canonical community schema for `.claude/settings.json`. Its `hooks` object
+  enumerates the full upstream event surface (30 events as of this pin), of which
+  Copse wires `PreToolUse` and `SessionStart`; the rest are intentionally
+  unsupported v1 (see the drift test's `CLAUDE_INTENTIONALLY_UNSUPPORTED_EVENTS`).
+- **Cursor — community schema.** Cursor does not publish a first-party
+  `hooks.json` JSON schema on SchemaStore. The most widely used community schema
+  is the one shipped by the `cursor-hooks` npm package (referenced from the Cursor
+  hooks docs' "enable JSON Schema validation" section). It lags the Cursor docs
+  (it publishes 6 events; Cursor's docs describe more), which is expected for a
+  community pin — our adapter deliberately knows a **superset**. The drift detector
+  only requires that every event this schema _publishes_ is either wired or listed
+  as intentionally-unsupported; adapter-ahead-of-schema is allowed.
+
+## Re-vendoring a pin
+
+This is the **only** step that touches the network, and it is run by a human/agent
+on purpose — never by the app or CI:
+
+```bash
+# Claude (SchemaStore):
+curl -sSL -o schemas/vendor/claude-code-settings.schema.json \
+  https://www.schemastore.org/claude-code-settings.json
+
+# Cursor (community, bump the pinned version deliberately):
+curl -sSL -o schemas/vendor/cursor-hooks.schema.json \
+  https://unpkg.com/cursor-hooks@<version>/schema/hooks.schema.json
+
+# Then update the table above (sha256 via `sha256sum`, dates, versions) and
+# re-run the drift detector; if it fails, either wire the new event(s) or add
+# them to the intentionally-unsupported list with a reason.
+npm test -- --test-name-pattern "vendor-schema-drift"
+```
+
+See `docs/plans/hooks-and-feature-packs.md` (issue G3) for the design decision.