feat: branches/worktrees tabs, canvas selection + solo, zoom-bug fix

[lukataylo]

Summary

• Branches + Worktrees tabs ship as siblings of Layers in the left side panel. Click a branch row to pan-and-zoom canvas to its frames; Cmd-click toggles Solo mode (other branches hidden, banner pinned). Click a worktree row to set the dispatch target — surfaces as a → ~/path chip in the TopBar and threads through to MCP as worktreeHint on the dispatch payload.
• Cross-browser canvas zoom fix — Safari pinch was killing the toolbar layout because (a) the wheel listener was rebinding on every zoom event and dropping preventDefault under fast pinches, and (b) Safari fires gesturestart/change/end instead of wheel+ctrl during a pinch, so our handler was silent. Wheel listener now binds once via a ref; Safari gesture handlers drive zoom directly from e.scale. All chrome z-indexes lifted to 95–110.
• Marketing route blocked by ad-blockers — CookieBanner.tsx / CookiePolicy.tsx paths matched uBlock/Safari Content Blocker heuristics → ERR_BLOCKED_BY_CONTENT_BLOCKER on lazy import. Renamed to ConsentNotice.tsx / StoragePolicy.tsx. URLs preserved (/cookies, /cookie-policy still route).

What's in the box

Selection model (new)

• apps/web/src/state/selectionStore.ts — small useSyncExternalStore + localStorage store owning selectedBranchId / soloBranchId / activeWorktreeId. Setters auto-interlock (selecting a new branch exits Solo; entering Solo selects the branch).
• registerFitToHook(rect) in plugins/registry.ts — Branches plugin can pan canvas to a world rect without importing canvas internals (same escape-hatch pattern as registerSelectFrameHook).
• SoloBanner pinned at canvas top with Exit Solo button so the mode can't get stuck even if both panels are pill-collapsed.

Branches panel

• Real branch data from BoardStore + stubbed PR/ahead-behind metadata (deterministic by branch name). Banner declares what's stubbed.
• Grouped by status (Active / Stale 30d+ / Merged); filter chips (Active / Mine / Stale / All); search input.
• Selection paints accent left-border + bg tint + "Focused on canvas" status line. Per-row actions: Check out, Open PR, Solo. Esc clears.

Worktrees panel

• Stubbed 3-row list in the shape the future /api/worktrees endpoint will return. Banner declares the data is stubbed.
• Selecting a row writes activeWorktreeId to the selection store. No canvas pan (worktree = future-tense dispatch target, not visual focus).

TopBar worktree chip

• New → ~/path chip right of the MCP chip; click does nothing (status only); hides when no worktree is active.

MCP wire

• CreateDispatchRequest.worktreeHint?: string in @foldo/protocol.
• useDispatchFlow and DomEditor save-to-source both read selectionStore.activeWorktreeId at dispatch time and attach the path.
• Server attaches worktreeHint to the in-flight Dispatch object before broadcasting + routing to /ws/mcp (not yet persisted — schema migration is a follow-up).
• MCP bridge logs worktree hint: <path> as a dispatch.progress event. Honouring it as cwd in runApplyEdit is the next backend piece.

SidePanel pill collapse

• Both LeftPanel and RightPanel get a manual ‹/› collapse button. Collapsed = 36px vertical icon rail with one button per tab; click expands + activates that tab. State persisted to localStorage per side.

Canvas zoom

• Canvas.tsx wheel listener now reads zoom through a zoomRef instead of listing viewport.zoom in effect deps. Listener binds once on mount.
• Safari gesturestart / gesturechange / gestureend listeners drive zoom from e.scale and preventDefault Safari's visual-viewport zoom that previously pushed toolbars off-screen.
• Chrome chrome path unchanged (wheel+ctrlKey).

Polish

• Comment pin shadow uses filter: drop-shadow so the teardrop outline traces correctly instead of haloing.
• Markdown frame "TINTS ON" button no longer wraps to two lines (whitespace-nowrap + flex-shrink-0).
• Inspect (DomEditor) tightened (24px controls, smaller gaps); Layers panel typography tightened (11–12px font, 24px rows); SidePanel + TopBar both sit on the 12px left edge.
• Demo User chip height now matches Capture/Tests/Share.

Plugin substrate (root cause of "3 toolbars" bug)

• PluginRegistry.install is now idempotent by manifest.id; new registry.reset() called from bootPlugins so dev-mode HMR no longer accumulates duplicate plugin contributions.

Cleanup

• Deleted apps/web/src/components/LeftRail.tsx. Its foldo-canvas-leftrail + foldo-rail-tool-* testids now live on the bottom PluginToolBar, so the existing e2e suite keeps clicking tools by name.
• core-plugins-still-work.spec.ts no longer asserts both legacy and new toolbar testids.

Test plan

• npm run typecheck — clean across all 8 workspaces.
• npx vitest run — 150 passed / 12 skipped (pre-existing).
• npm --workspace @foldo/web run build — clean; App-*.js is 173.6 → 177.3 KB (+3.7 KB raw / +1.1 KB gzip). Bundle budget headroom: 69%.
• prettier --check on new files — formatted.
• Playwright e2e (will run in CI).
• Manual smoke: branches panel selection + pan-to-fit, worktree chip in topbar, Solo banner + exit, comment pin shadow on light/dark, "TINTS ON" wrap, Inspect density, canvas pinch zoom in Chrome + Safari, marketing routes load with ad-blockers active.

Notes for review

• worktreeHint is intentionally not persisted on the dispatches table yet — it's attached in-flight only. DLQ retries after a process restart will lose the hint but the dispatch still succeeds; persisting it is the next schema migration.
• Stub banners on the Branches + Worktrees panels make it visually obvious which pieces are awaiting backend wiring (/api/branches/:id/git, /api/worktrees).

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