feat: Firefox MV3 add-on via extension-shared workspace package

CLAUDE.md

@@ -6,7 +6,9 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 Two packages are merged to main and working:
 - `@gitmarks/core` (`packages/core/`) — schemas, GitHub Contents API client with optimistic concurrency, ULID/URL helpers (incl. opt-in tracking-param stripping), pure mutation helpers, example fixtures. 65 unit tests.
-- `@gitmarks/extension-chrome` (`packages/extension-chrome/`) — MV3 Chrome extension with toolbar save, two-way native-tree sync, 5-min poll, initial reconciliation, opt-in tracking-param stripping settings flag. 97 unit tests + 4 Playwright e2e tests (2 e2e skipped pending Playwright limitation fixes — see issue history).
+- `@gitmarks/extension-shared` (`packages/extension-shared/`) — canonical owner of the cross-browser extension code: popup, options, background, all of `src/lib/`, and the chrome/browser stub. 96 unit tests live here. Consumed by both browser shells via `workspace:*`. Uses `browser.*` via `webextension-polyfill`.
+- `@gitmarks/extension-chrome` (`packages/extension-chrome/`) — Chrome MV3 shell. Manifest + Vite/crxjs build + Playwright e2e (4 passing, 2 skipped — see issue history for the activeTab/Playwright limitation). Source files are thin entries that re-export from `extension-shared` via its `exports` map.
+- `@gitmarks/extension-firefox` (`packages/extension-firefox/`) — Firefox MV3 shell. Manifest + plain Vite build + manual smoke test (Playwright Firefox doesn't reliably drive WebExtensions). Targets Firefox 121+ for MV3 SW parity. Load via `about:debugging` → "Load Temporary Add-on".
 
 Pending packages (in dependency order): Firefox build, web UI (read + search + tags), web UI (write + bulk ops), Safari.
 
@@ -88,7 +90,7 @@ pnpm --filter @gitmarks/extension-chrome e2e
 1. ✅ `@gitmarks/core`
 2. ✅ Chrome MVP (toolbar save)
 3. ✅ Chrome native tree integration
-4. ⬜ Firefox build (`webextension-polyfill`) — issue [#23](https://github.com/paperhurts/gitmarks/issues/23)
+4. ✅ Firefox MV3 add-on (`webextension-polyfill` + extension-shared) — issue [#23](https://github.com/paperhurts/gitmarks/issues/23)
 5. ⬜ Web UI v1: list / search / tag management — issue [#24](https://github.com/paperhurts/gitmarks/issues/24)
 6. ⬜ Web UI v2: bulk operations + trash + export — issue [#25](https://github.com/paperhurts/gitmarks/issues/25)
 7. ⬜ Safari (`safari-web-extension-converter`) — issue [#26](https://github.com/paperhurts/gitmarks/issues/26)

README.md

@@ -8,7 +8,8 @@ you control.
 
 **Status:** Chrome extension is functional end-to-end (save via toolbar
 button, two-way sync with the native bookmark tree, 5-min poll for remote
-changes, automatic conflict retry). Firefox / Safari / web UI are next in
+changes, automatic conflict retry). Firefox MV3 add-on shipping the same
+source as Chrome via a shared package. Safari / web UI are next in
 the roadmap. See `spec.md` for the full design.
 
 ## Features (Chrome, today)
@@ -32,7 +33,9 @@ the roadmap. See `spec.md` for the full design.
 | Package | Role |
 |---|---|
 | `@gitmarks/core` | Shared TypeScript library: schemas (Zod), GitHub Contents API client with optimistic concurrency, ULID + URL helpers, pure mutation helpers |
-| `@gitmarks/extension-chrome` | Chrome MV3 extension. Save tabs, two-way sync with the native bookmark tree, 5-min poll, reconciliation |
+| `@gitmarks/extension-shared` | Cross-browser extension source — popup, options, background, lib/ helpers. Consumed by both browser shells via `workspace:*`. 96 unit tests live here. |
+| `@gitmarks/extension-chrome` | Chrome MV3 shell. Manifest + Vite/crxjs build + Playwright e2e. Thin entry files import from `extension-shared`. |
+| `@gitmarks/extension-firefox` | Firefox MV3 shell. Manifest + plain Vite build. Same source as Chrome via `extension-shared`. Load via `about:debugging`. |
 
 ## Quick start (Chrome extension)
 
@@ -88,7 +91,7 @@ The repo is a pnpm workspace monorepo. Each package has its own
 ## Architecture
 
 ```
-[Chrome ext] [Firefox ext (planned)] [Safari ext (planned)]    [Web UI (planned)]
+[Chrome ext] [Firefox ext] [Safari ext (planned)]    [Web UI (planned)]
        \             |                       /                       /
         \            |                      /                       /
          v           v                     v                       v
@@ -122,7 +125,7 @@ The load-bearing invariants:
 - ✅ Chrome MVP — toolbar-button save flow
 - ✅ Chrome native tree integration — listeners, reconcile, poll loop
 - ✅ Tracking-param stripping (opt-in)
-- ⬜ Firefox build ([#23](https://github.com/paperhurts/gitmarks/issues/23))
+- ✅ Firefox MV3 add-on ([#23](https://github.com/paperhurts/gitmarks/issues/23))
 - ⬜ Web UI v1: list + search + tag management ([#24](https://github.com/paperhurts/gitmarks/issues/24))
 - ⬜ Web UI v2: bulk operations + trash + export ([#25](https://github.com/paperhurts/gitmarks/issues/25))
 - ⬜ Safari ([#26](https://github.com/paperhurts/gitmarks/issues/26))