hooks: two-tier design hook — immediate per-edit rules + full-set Stop deep pass

Eval evidence showed the per-edit PostToolUse stream fires overwhelmingly
on copy-level rules (em-dash-overuse ~97x/session) and measurably makes
models more conservative, while a full-detector pass at completion is what
actually fixes contrast/padding/glow. Split the hook accordingly:

- Per-edit (PostToolUse) now surfaces only IMMEDIATE_TIER_RULES: broken
  output (broken-image, text-overflow, clipped-overflow-container,
  body-text-viewport-edge), objective contrast/legibility failures
  (low-contrast, gray-on-color, tiny-text), single-property mechanical
  slop (gradient-text, dark-glow), and design-system drift (the four
  design-system-* rules, which compound if left uncorrected). Everything
  else defers. Override with hook.perEditRules: "all" in
  .impeccable/config.json. Tiering is off for Cursor/Copilot harnesses,
  which have no Stop pass wired, so nothing gets silently dropped there.

- Stop deep pass (runStopHook): runs the FULL rule set over every UI file
  touched this session (tracked via the existing hook.cache.json session
  state; deferred-only edits now mark the file touched), dedupes against
  everything already surfaced per-edit, honors ignore-rule/file/value and
  inline disables, reuses the [impeccable@1] envelope, and no-ops fast
  when no UI files were touched. Emits hookSpecificOutput
  { hookEventName: "Stop", additionalContext } per the Claude Code SDK
  Stop contract (conversation continues so the model can act on it).
  Second Stop fire is silent - deep-pass findings are remembered.

- Wiring: Stop entries (timeout 30) in plugin/hooks/hooks.json, the
  .claude settings + .codex hooks manifests (transformers + hook-admin
  repair path). Claude Code and Codex both dispatch a native Stop event;
  Cursor's stop hook is inconsistently dispatched (pre-write gate stays)
  and Copilot's agentStop/sessionEnd don't inject model context, so
  neither gets a Stop entry - documented in reference/hooks.md.

- Tests: tiering split/override/harness gating, Stop dedupe + silent
  no-touched-files + ignore machinery + kill switches; existing per-edit
  tests moved to immediate-tier rule ids. 181 tests green; smoke-tested
  the built dist skill end to end (glow surfaced per-edit, em-dash only
  at Stop, second Stop silent).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

skill/reference/hooks.md

@@ -4,6 +4,8 @@ Manage the **design detector hook** for the current project.
 
 The hook runs the impeccable design detector on direct file edits to design-relevant files (`.tsx`, `.jsx`, `.html`, `.vue`, `.svelte`, `.astro`, `.css`, `.scss`, `.sass`, `.less`, `.ts`, `.js`). Claude Code, Codex, and GitHub Copilot use a post-tool-use hook and push a short system reminder into the agent's context after the edit; findings get a correction prompt, pending issues get a re-nudge, and clean UI-ish files get a short ack unless quiet mode is on (`hook.quiet` in config). Plain `.ts` and `.js` files are still scanned, but stay quiet unless the detector finds something. Cursor uses `preToolUse` to block bad proposed writes before they land and stays silent when it allows a clean write.
 
+The detector rules run in two tiers. The per-edit hook surfaces only the immediate tier: mechanical, unambiguous problems worth interrupting an edit for, such as broken images, overflowing or clipped content, contrast and legibility failures, gradient text, glow shadows, and design-system drift. Everything else (copy cadence, palette and typography taste, layout rhythm) is deferred to a deep pass on the `Stop` hook event, which runs the full rule set over every UI file touched in the session and surfaces the remaining findings once, deduplicated against what the per-edit pass already reported. A session that touched no UI files stops silently. Set `hook.perEditRules` to `"all"` in `.impeccable/config.json` to restore the full rule set on every edit. The Stop deep pass is wired for Claude Code and Codex, which both dispatch a native `Stop` hook event. Cursor does not get one (its stop hook is not consistently dispatched; the pre-write gate covers it), and GitHub Copilot's stop-style events do not feed context back to the model, so Copilot keeps the full rule set per edit instead of deferring.
+
 This command toggles the hook **per project** by editing `.impeccable/config.json` (the unified Impeccable config; hook runtime settings live under its `hook` key, and shared detector ignores live under `detector`). Per-developer overrides, including the install consent decision (`hook.consent`) the CLI records, live in the gitignored `.impeccable/config.local.json`. Set `hook.enabled: false` to turn the hook off, `hook.quiet: true` to silence the clean/pending acks, or `hook.auditLog` to a file path for an NDJSON log. The legacy `IMPECCABLE_HOOK_DISABLED`, `IMPECCABLE_HOOK_QUIET`, and `IMPECCABLE_HOOK_LOG` env vars are still honored and override these config values when set.
 
 Declare server-side template extensions under **`detector.extensions`** when the project uses Blade, Twig, ERB, or Handlebars files; the hook skips them otherwise because they sit outside the built-in extension list. One entry per extension, `{ "ext": ".blade.php", "engine": "html" }`. `engine` picks the analyzer (`html` for markup templates, `text` for JS/TS/CSS-like files) and defaults to `html`. Match against the end of the filename, so double extensions like `.blade.php` and `.html.erb` work. Config only adds extensions; the built-in list always applies.