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+# Implementation Plan: F11 — Preview Toolbar as the Primary Interaction Surface (#43)
+
+**Spec:** `docs/superpowers/specs/2026-06-12-f11-preview-toolbar-interaction-surface.md`
+**Anchor:** Feature `benstull/vscode-cowriting-plugin#43` (F11, `type/feature`, `priority/P1`)
+**Session:** vscode-cowriting-plugin-0037
+
+This plan transcribes the spec's §7.2 slicing plan into concrete, file-level
+tasks. Each slice is independently green (unit + host E2E) before the next. Host
+E2E is this app's required tier (no browser/deploy stage — a VS Code extension);
+no LLM in CI (edit turns stubbed). The webview's visual rendering, the adaptive
+label, and the selection→source DOM lookup are manual-smoke only.
+
+---
+
+## SLICE-1 — Pin baseline button + reachability *(the immediate win)*
+
+Homes the orphaned `cowriting.pinDiffBaseline` command and gives the writer a
+reachable Pin control in the preview toolbar.
+
+**Tasks**
+
+1. **Host message routing** (`src/trackChangesPreview.ts`): extract the inline
+   `onDidReceiveMessage` body into a private `handleWebviewMessage(document, m)`
+   method; add a `pinBaseline` branch that calls `this.diffView.pin(document)`
+   (the *previewed* document — not `activeTextEditor`). The existing
+   `onDidChangeBaseline` subscription already re-renders with cleared marks.
+2. **Test seam**: add `receiveMessage(uriString, m)` that resolves the doc and
+   calls `handleWebviewMessage`, so host E2E can simulate the raw webview message
+   and exercise the real routing.
+3. **Webview** (`media/preview.ts` + `.css`): add a `⌖ Pin baseline` button in
+   `#cw-header`; click → `postMessage({ type: "pinBaseline" })`; theme-aware CSS.
+4. **Shell HTML** (`shellHtml`): add the `<button id="cw-pin">` to the header row.
+5. **Reachability** (`package.json`): flip `cowriting.pinDiffBaseline`'s
+   `commandPalette` `when` from `false` to `editorLangId == markdown`.
+
+**Host E2E** (`test/e2e/suite/trackChangesPreview.test.ts` or new f11 suite):
+open a markdown fixture with a divergent baseline → some block marked; simulate
+`{type:"pinBaseline"}` via `receiveMessage` → `getLastModel` shows every block
+`unchanged` (marks cleared) and `getBaseline(key).reason === "pinned"`.
+
+**Unit:** none new (pure layer untouched this slice).
+
+---
+
+## SLICE-2 — Block-offset emission *(INV-36 data layer)*
+
+Shared pure helper wrapping each rendered block with `data-src-start`/`-end`
+(source char offsets from `BlockWithRange`) in **both** `renderReview` and
+`renderPlain`. vscode-free, DOM-free, deterministic (extends INV-22/33). No UI.
+
+**Tasks**
+
+1. `src/trackChangesModel.ts`: a shared internal helper that prepends
+   `data-src-start="N" data-src-end="M"` to each block's wrapping element, routed
+   from both render paths using the existing `splitBlocksWithRanges` offsets.
+2. Skip blocks with no live-source range (deletion-only / proposal blocks).
+
+**Unit** (`test/trackChangesModel.test.ts`): `data-src-start/end` present and
+correct on every block for both modes (offsets equal `BlockWithRange` ranges);
+determinism (same inputs → identical HTML).
+
+---
+
+## SLICE-3 — Edit Document button + hunk path *(INV-37 document half)*
+
+**Tasks**
+
+1. `src/trackChangesModel.ts`: pure `diffToHunks(currentText, rewrittenText):
+   Array<{ start; end; replacement }>` — vscode-free, deterministic.
+2. `src/trackChangesPreview.ts`: `runEditAndPropose(document, target, instruction)`
+   private routine; `askClaude`/`document` branch → host `showInputBox` →
+   `runEditTurn` over full text → `diffToHunks` → one F4 `propose()` per hunk.
+3. `package.json`: register `cowriting.editDocument` (document-scoped), routed
+   through `runEditAndPropose({kind:"document"})`; for `#42` reuse.
+4. Webview: `✦ Ask Claude to Edit Document` button (no-selection state) →
+   `postMessage({ type: "askClaude", scope: "document" })`.
+
+**Unit:** `diffToHunks` over fixtures (single hunk → one range; multi-hunk →
+disjoint ranges + correct replacements; unchanged → zero hunks; whole-doc
+replacement → one full-range hunk).
+
+**Host E2E:** simulate `{askClaude, scope:"document"}` with a stubbed multi-hunk
+rewrite → **N** proposals matching the hunks.
+
+---
+
+## SLICE-4 — Adaptive Edit Selection *(INV-37 selection half; INV-36 consumer)*
+
+**Tasks**
+
+1. Webview: `selectionchange` listener flips the Ask-Claude label (Edit Selection
+   ⇆ Edit Document); selection→nearest-`data-src` ancestor resolution →
+   `postMessage({ type:"askClaude", scope:"selection", start, end })`.
+2. Host: `askClaude`/`selection` branch → `runEditAndPropose({kind:"range",
+   start, end})` → one `runEditTurn` → one F4 `propose()` over the block-union.
+3. Edge: selection resolving to no live block → fall back to document scope.
+
+**Host E2E:** simulate `{askClaude, scope:"selection", start, end}` with a stubbed
+edit turn → exactly **one** proposal over the resolved range, anchored inline.
+
+---
+
+## SLICE-5 — Gateway, edges, tests & docs
+
+**Tasks**
+
+1. `package.json`: add `cowriting.showTrackChangesPreview` to `editor/title` with
+   `when: editorLangId == markdown` (minimal right-click gateway).
+2. Non-authorable disabling: Pin + Ask-Claude controls render disabled when
+   `!isAuthorable(document)`; annotations toggle stays active.
+3. Host E2E: gateway command opens the panel; controls inert on non-authorable.
+4. `docs/MANUAL-SMOKE-F11.md` (live smoke script per spec §6.8).
+5. README F11 section.
+
+---
+
+## Done = #43 acceptance (spec §7.3)
+
+Preview toolbar hosts annotations checkbox + Pin baseline + single adaptive
+Ask-Claude (Edit Selection ⇆ Edit Document) routing through existing F4/F3/F6;
+edits surface as proposals (one for a selection, per-hunk for a document
+rewrite); a right-click entry opens the preview; the pin command is no longer
+orphaned; unit + host E2E green; live smoke performed once.