# F6 Diff-View Toggle Implementation Plan > **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking. **Goal:** Add a one-gesture diff-view toggle that flips a tracked document into a `vscode.diff` against a coauthoring baseline (live document on the right), where the baseline auto-advances at every machine landing and can be pinned on demand. **Architecture:** One vscode-free `BaselineStore` (the `CoauthorStore` pattern — Node `fs`, one JSON per docPath under VS Code workspace storage, never the repo — INV-19) plus one vscode-layer `DiffViewController` (content provider for a `cowriting-baseline:` scheme, baseline lifecycle, toggle via the tab-groups API). The machine-landing signal is one additive `onDidApplyAgentEdit` event on `AttributionController` — the seam is the single ingress (INV-9), so it is the single signal. Everything else is reused unchanged. **Tech Stack:** TypeScript, VS Code extension API (`vscode.diff`, `TextDocumentContentProvider`, `window.tabGroups`), vitest (unit), `@vscode/test-electron` + mocha (host E2E). No LLM anywhere in F6 or its tests. **Source spec:** `vscode-cowriting-plugin-content/specs/coauthoring-diff-view.md` (F6, Feature #17). Section refs (§6.x, INV-18/19, PUC-x) point into it. --- ## File Structure - **Create** `src/baselineStore.ts` — vscode-free `BaselineStore`: `load`/`save`/`baselinePath` for one `Baseline` JSON per docPath under a storage dir. Mirrors `src/store.ts`. - **Create** `test/baselineStore.test.ts` — vitest round-trip / path / overwrite / missing-null unit tests. Mirrors `test/store.test.ts`. - **Modify** `src/attributionController.ts` — add the additive `onDidApplyAgentEdit` event emitter; fire it after a real (non-no-op) seam apply succeeds. Seam signature/return unchanged. - **Create** `src/diffViewController.ts` — vscode-layer controller: registers the `cowriting-baseline:` content provider (+ `onDidChange` refresh), owns baseline lifecycle (`ensureBaseline`/`advance`/`pin`), `toggle` via tab groups, registers the two commands, exposes the test-facing surface, degrades to in-memory on storage failure. - **Modify** `src/extension.ts` — construct `BaselineStore` from `context.storageUri` + `DiffViewController`; wire `ensureBaseline` into `renderIfOpen`; subscribe `advance` to `attributionController.onDidApplyAgentEdit`; add `diffViewController` to `CowritingApi`; add the two commands to the no-folder stub list. - **Modify** `package.json` — contribute the two commands + the `ctrl+alt+d` keybinding. - **Create** `test/e2e/fixtures/workspace/docs/diffview.md` — the F6 suite's owned fixture (disjoint from sample/attrib/proposal/crossrung). - **Create** `test/e2e/suite/diffView.test.ts` — host E2E per §6.8. - **Modify** `test/e2e/suite-no-workspace/noWorkspace.test.ts` — add the two new commands to the stub-registration assertion. - **Create** `docs/MANUAL-SMOKE-F6.md` — live smoke per §6.8. - **Modify** `README.md` — one-line F6 pointer in the develop/feature section. --- ## Slice → Task map - **SLICE-1** (BaselineStore + unit): Task 1. - **SLICE-2** (seam event + controller lifecycle): Tasks 2, 3. - **SLICE-3** (toggle UX + package.json + API + wiring): Tasks 4, 5, 6. - **SLICE-4** (host E2E + smoke + README): Tasks 7, 8, 9. --- ## Task 1: `BaselineStore` (vscode-free) + unit tests — SLICE-1 **Files:** - Create: `src/baselineStore.ts` - Test: `test/baselineStore.test.ts` - [ ] **Step 1: Write the failing test** Create `test/baselineStore.test.ts`: ```typescript import { describe, it, expect, beforeEach, afterEach } from "vitest"; import * as fs from "node:fs"; import * as os from "node:os"; import * as path from "node:path"; import { BaselineStore, type Baseline } from "../src/baselineStore"; let dir: string; beforeEach(() => { dir = fs.mkdtempSync(path.join(os.tmpdir(), "baseline-store-")); }); afterEach(() => { fs.rmSync(dir, { recursive: true, force: true }); }); function sample(docPath = "notes/chapter-1.md"): Baseline { return { docPath, text: "hello\nworld\n", capturedAt: "2026-06-11T00:00:00.000Z", reason: "opened" }; } describe("BaselineStore", () => { it("returns null for a document with no baseline", () => { expect(new BaselineStore(dir).load("notes/chapter-1.md")).toBeNull(); }); it("computes the baseline path as baselines/.json", () => { const store = new BaselineStore(dir); expect(store.baselinePath("notes/chapter-1.md")).toBe( path.join(dir, "baselines", "notes", "chapter-1.md.json"), ); }); it("save then load round-trips the baseline (including nested docPaths)", () => { const store = new BaselineStore(dir); const b = sample(); store.save(b.docPath, b); expect(store.load(b.docPath)).toEqual(b); }); it("overwrites in place: the newest epoch wins, no history kept", () => { const store = new BaselineStore(dir); store.save("d.md", { docPath: "d.md", text: "v1", capturedAt: "2026-06-11T00:00:00.000Z", reason: "opened" }); store.save("d.md", { docPath: "d.md", text: "v2", capturedAt: "2026-06-11T00:01:00.000Z", reason: "pinned" }); expect(store.load("d.md")).toEqual({ docPath: "d.md", text: "v2", capturedAt: "2026-06-11T00:01:00.000Z", reason: "pinned" }); }); it("writes pretty JSON with a trailing newline", () => { const store = new BaselineStore(dir); const b = sample("d.md"); store.save("d.md", b); const raw = fs.readFileSync(store.baselinePath("d.md"), "utf8"); expect(raw).toBe(JSON.stringify(b, null, 2) + "\n"); }); }); ``` - [ ] **Step 2: Run the test to verify it fails** Run: `npx vitest run test/baselineStore.test.ts` Expected: FAIL — cannot resolve `../src/baselineStore`. - [ ] **Step 3: Write the minimal implementation** Create `src/baselineStore.ts`: ```typescript /** * BaselineStore — load/save one diff-view baseline JSON per document (F6 §6.3). * The CoauthorStore shape (src/store.ts): vscode-free (Node fs only, unit- * testable), one file per docPath. INV-19: the storage dir is VS Code's * per-workspace extension storage, NEVER the repo — so the baseline can never * be committed, merged, or read by another rung, and the sidecar / cross-rung * contract (INV-14..17) are untouched by construction. */ import * as fs from "node:fs"; import * as path from "node:path"; export type BaselineReason = "opened" | "machine-landing" | "pinned"; export interface Baseline { docPath: string; /** full document text captured at the epoch (from the buffer, not disk — §6.3). */ text: string; capturedAt: string; reason: BaselineReason; } export class BaselineStore { /** @param storageDir absolute VS Code workspace-storage dir (context.storageUri.fsPath). */ constructor(private readonly storageDir: string) {} /** `/baselines/.json` (§6.3). */ baselinePath(docPath: string): string { return path.join(this.storageDir, "baselines", `${docPath}.json`); } load(docPath: string): Baseline | null { const p = this.baselinePath(docPath); if (!fs.existsSync(p)) return null; return JSON.parse(fs.readFileSync(p, "utf8")) as Baseline; } /** Newest epoch wins — overwrite in place, no history (state-not-history, the F3/F4 precedent). */ save(docPath: string, baseline: Baseline): void { const p = this.baselinePath(docPath); fs.mkdirSync(path.dirname(p), { recursive: true }); fs.writeFileSync(p, JSON.stringify(baseline, null, 2) + "\n", "utf8"); } } ``` - [ ] **Step 4: Run the test to verify it passes** Run: `npx vitest run test/baselineStore.test.ts` Expected: PASS (5 tests). - [ ] **Step 5: Typecheck** Run: `npm run typecheck` Expected: no errors. - [ ] **Step 6: Commit** ```bash git add src/baselineStore.ts test/baselineStore.test.ts git commit -m "feat(f6): BaselineStore — vscode-free per-doc baseline persistence (SLICE-1) F6 §6.2/§6.3, INV-19. One JSON per docPath under VS Code workspace storage, never the repo. Mirrors CoauthorStore; unit-tested round-trip/paths/overwrite." ``` --- ## Task 2: Additive `onDidApplyAgentEdit` seam event — SLICE-2 **Files:** - Modify: `src/attributionController.ts` (fields near `:56-64`; fire near `:278`) The seam (`applyAgentEdit`) is the single machine-edit ingress (INV-9). Adding one event on it makes it the single machine-landing signal — no call-site wiring, future seam drivers can't forget it (§6.7). This task has no behavioral test of its own; it is exercised by the SLICE-4 host E2E (accept advances the baseline). Verify with typecheck + build + the existing suites staying green. - [ ] **Step 1: Add the emitter field and public event** In `src/attributionController.ts`, in the `AttributionController` class field block (currently ending around line 64 with `private visible = true;`), add: ```typescript /** * F6 (§6.2/§6.4): the single machine-landing signal. Fired after a real * (non-no-op) seam apply succeeds. INV-9 makes the seam the sole machine-edit * ingress, so this is the sole signal — DiffViewController subscribes to * advance the baseline; no call-site wiring, no future driver can forget it. */ private readonly applyEmitter = new vscode.EventEmitter<{ document: vscode.TextDocument }>(); readonly onDidApplyAgentEdit: vscode.Event<{ document: vscode.TextDocument }> = this.applyEmitter.event; ``` - [ ] **Step 2: Register the emitter for disposal** In the constructor, the first `this.disposables.push(...)` currently reads: ```typescript this.disposables.push(this.agentType, this.humanType, this.statusItem, this.output); ``` Change it to also dispose the emitter: ```typescript this.disposables.push(this.agentType, this.humanType, this.statusItem, this.output, this.applyEmitter); ``` - [ ] **Step 3: Fire the event after a successful real apply** In `applyAgentEdit`, the tail currently reads (around line 266-278): ```typescript const ok = await vscode.workspace.applyEdit(we); const removed = this.pending.unregister(pendingEdit); if (ok && removed) { // ... existing WARN-on-mismatch block unchanged ... this.output.appendLine( "WARN: seam edit applied but its change event never matched the registration " + "(host minimized differently?) — the edit may be mis-attributed (INV-9).", ); } return ok; ``` Insert the fire just before `return ok;` (the no-op replacement already returned at `minStart === minEnd` above, so reaching here means a real change): ```typescript if (ok) { // F6 (INV-18): a real machine landing — signal the baseline to advance so // this text never shows as a change in the diff view. Fire regardless of // attribution-match bookkeeping above; the landing happened either way. this.applyEmitter.fire({ document }); } return ok; ``` > Note the existing `if (ok && removed)` WARN block stays exactly as is — only the new `if (ok) { ... fire ... }` is added above `return ok;`. - [ ] **Step 4: Typecheck** Run: `npm run typecheck` Expected: no errors. - [ ] **Step 5: Existing unit + E2E suites stay green** Run: `npx vitest run` Expected: PASS (unchanged — the emitter has no unit consumer yet). Run: `npm run test:e2e` Expected: PASS (the seam's signature and return contract are unchanged; the added fire has no listener yet). - [ ] **Step 6: Commit** ```bash git add src/attributionController.ts git commit -m "feat(f6): onDidApplyAgentEdit — the single machine-landing signal (SLICE-2) F6 §6.2/§6.4, INV-9/INV-18. Additive EventEmitter on the seam owner, fired after a real (non-no-op) applyEdit succeeds. Seam signature/return unchanged." ``` --- ## Task 3: `DiffViewController` — content provider + baseline lifecycle — SLICE-2 **Files:** - Create: `src/diffViewController.ts` This task creates the controller with the content provider, the `ensureBaseline`/`advance`/`pin` lifecycle, the storage-unavailable fallback, and the test-facing surface — but **not yet wired into `extension.ts`** (Task 5) and with the `toggle` UX added in Task 4. Verify with typecheck + build. (Host-layer behavior is verified by the SLICE-4 E2E — the F2–F5 precedent: vscode-dependent controllers are covered by host E2E, not unit tests.) - [ ] **Step 1: Create the controller (lifecycle + provider, no toggle yet)** Create `src/diffViewController.ts`: ```typescript /** * DiffViewController — F6 diff-view toggle (spec §6.2/§6.4). Owns the baseline * lifecycle (initialize at first track / advance at every machine landing / pin * on demand), serves the baseline as a readonly `cowriting-baseline:` virtual * document, and toggles a native vscode.diff (baseline left, the LIVE document * right). A pure view: never mutates the document, sidecar, or attribution * state (INV-19). Baselines persist via the vscode-free BaselineStore; if * storage is unavailable the controller degrades to in-memory baselines + one * warning (reload survival is lost; the toggle still works) — §6.5 PUC-5. */ import * as path from "node:path"; import * as vscode from "vscode"; import { BaselineStore, type Baseline, type BaselineReason } from "./baselineStore"; export const BASELINE_SCHEME = "cowriting-baseline"; export class DiffViewController implements vscode.Disposable { private readonly disposables: vscode.Disposable[] = []; /** Source of truth for the content provider; mirrors what the store persists. */ private readonly baselines = new Map(); private readonly onDidChangeEmitter = new vscode.EventEmitter(); private storageWarned = false; constructor( private readonly store: BaselineStore | null, private readonly rootDir: string, ) { const provider: vscode.TextDocumentContentProvider = { onDidChange: this.onDidChangeEmitter.event, provideTextDocumentContent: (uri) => { const docPath = this.docPathFromBaselineUri(uri); return this.baselines.get(docPath)?.text ?? ""; }, }; this.disposables.push( this.onDidChangeEmitter, vscode.workspace.registerTextDocumentContentProvider(BASELINE_SCHEME, provider), vscode.commands.registerCommand("cowriting.toggleDiffView", () => this.toggle(vscode.window.activeTextEditor), ), vscode.commands.registerCommand("cowriting.pinDiffBaseline", () => this.pinCommand(vscode.window.activeTextEditor), ), ); } // ---- tracking / uri helpers -------------------------------------------------------- private isTracked(document: vscode.TextDocument): boolean { return document.uri.scheme === "file" && document.uri.fsPath.startsWith(this.rootDir); } private docPathOf(uri: vscode.Uri): string { return vscode.workspace.asRelativePath(uri, false); } /** The readonly virtual-doc URI whose content the provider serves for this doc. */ private baselineUri(docPath: string): vscode.Uri { return vscode.Uri.from({ scheme: BASELINE_SCHEME, path: "/" + docPath }); } private docPathFromBaselineUri(uri: vscode.Uri): string { return uri.path.replace(/^\//, ""); } // ---- baseline lifecycle (§6.4) ----------------------------------------------------- /** First sight of a tracked doc: load the stored baseline, else capture `opened`. */ ensureBaseline(document: vscode.TextDocument): void { if (!this.isTracked(document)) return; const docPath = this.docPathOf(document.uri); if (this.baselines.has(docPath)) return; if (this.store) { try { const stored = this.store.load(docPath); if (stored) { this.baselines.set(docPath, stored); return; } } catch { this.warnStorageOnce(); } } this.capture(document, "opened"); } /** Machine landing (INV-18): re-capture so landed text never shows as a change. */ advance(document: vscode.TextDocument): void { if (!this.isTracked(document)) return; this.capture(document, "machine-landing"); } /** Human pin: baseline := now; the open diff visibly empties (left = right). */ pin(document: vscode.TextDocument): void { if (!this.isTracked(document)) return; this.capture(document, "pinned"); } /** Capture buffer text at this epoch, persist, and refresh any open diff's left side. */ private capture(document: vscode.TextDocument, reason: BaselineReason): void { const docPath = this.docPathOf(document.uri); const baseline: Baseline = { docPath, text: document.getText(), capturedAt: new Date().toISOString(), reason, }; this.baselines.set(docPath, baseline); if (this.store) { try { this.store.save(docPath, baseline); } catch { this.warnStorageOnce(); } } // An open diff re-requests the left side when its baseline URI changes. this.onDidChangeEmitter.fire(this.baselineUri(docPath)); } private warnStorageOnce(): void { if (this.storageWarned) return; this.storageWarned = true; void vscode.window.showWarningMessage( "Cowriting: diff-view storage is unavailable — baselines are kept in memory only and won't survive a reload.", ); } // ---- commands (toggle added in Task 4) --------------------------------------------- private pinCommand(editor: vscode.TextEditor | undefined): void { if (!editor || !this.isTracked(editor.document)) { void vscode.window.showWarningMessage("Cowriting: open a tracked workspace document to pin its diff baseline."); return; } this.pin(editor.document); } // ---- test-facing surface (§6.4) ---------------------------------------------------- getBaseline(docPath: string): { text: string; reason: BaselineReason; capturedAt: string } | undefined { const b = this.baselines.get(docPath); return b ? { text: b.text, reason: b.reason, capturedAt: b.capturedAt } : undefined; } /** Absolute on-disk path of this doc's persisted baseline, or undefined if in-memory. */ baselineFilePath(docPath: string): string | undefined { return this.store?.baselinePath(docPath); } dispose(): void { for (const d of this.disposables) d.dispose(); } } ``` > `toggle` and `isDiffOpen` are added in Task 4. The two `registerCommand` calls are already present so the commands exist from this task; `toggle` is referenced by `cowriting.toggleDiffView` and is added next — keep Task 3 and Task 4 in order, or the build fails on the missing `toggle` method. (If executing strictly task-by-task, add a temporary `private toggle(_e: vscode.TextEditor | undefined): void {}` stub in Step 1 and replace it in Task 4. The committed result after Task 4 has the real method.) To keep Task 3 independently building, include this stub at the end of the class (replaced in Task 4): ```typescript // Replaced by the real implementation in Task 4 (toggle UX, SLICE-3). private toggle(_editor: vscode.TextEditor | undefined): void { /* stub */ } ``` - [ ] **Step 2: Typecheck + build** Run: `npm run typecheck` Expected: no errors (the `toggle` stub satisfies the command registration). Run: `npm run build` Expected: succeeds. - [ ] **Step 3: Commit** ```bash git add src/diffViewController.ts git commit -m "feat(f6): DiffViewController — baseline lifecycle + content provider (SLICE-2) F6 §6.2/§6.4, INV-18/INV-19. ensure/advance/pin capture buffer text, persist via BaselineStore, refresh the open diff via onDidChange. Storage-unavailable degrades to in-memory + one warning. toggle UX lands in SLICE-3." ``` --- ## Task 4: Toggle UX via the tab-groups API — SLICE-3 **Files:** - Modify: `src/diffViewController.ts` (replace the `toggle` stub; add `isDiffOpen` + a title helper) - [ ] **Step 1: Replace the `toggle` stub with the real implementation** In `src/diffViewController.ts`, replace the Task-3 stub: ```typescript // Replaced by the real implementation in Task 4 (toggle UX, SLICE-3). private toggle(_editor: vscode.TextEditor | undefined): void { /* stub */ } ``` with the toggle + helpers: ```typescript /** * PUC-1: if this doc's baseline diff is the active/open tab → close it and * reveal the normal editor; if the active editor is a tracked doc with no diff * open → open vscode.diff (baseline left, the live document right). Untracked * → warn, no diff. */ private async toggle(editor: vscode.TextEditor | undefined): Promise { if (!editor || !this.isTracked(editor.document)) { void vscode.window.showWarningMessage( "Cowriting: open a tracked workspace document to toggle its diff view.", ); return; } const document = editor.document; const docPath = this.docPathOf(document.uri); const openTab = this.findDiffTab(document.uri); if (openTab) { await vscode.window.tabGroups.close(openTab); await vscode.window.showTextDocument(document, { preview: false }); return; } this.ensureBaseline(document); const baseline = this.baselines.get(docPath)!; const title = `${path.basename(docPath)} — my changes since ${this.epochLabel(baseline)}`; await vscode.commands.executeCommand( "vscode.diff", this.baselineUri(docPath), document.uri, title, { preview: false }, ); } /** The open baseline-diff tab for this document, if any. */ private findDiffTab(modified: vscode.Uri): vscode.Tab | undefined { for (const group of vscode.window.tabGroups.all) { for (const tab of group.tabs) { const input = tab.input; if ( input instanceof vscode.TabInputTextDiff && input.original.scheme === BASELINE_SCHEME && input.modified.toString() === modified.toString() ) { return tab; } } } return undefined; } /** Human-readable epoch for the diff tab title (§5 / §6.5). */ private epochLabel(baseline: Baseline): string { const time = new Date(baseline.capturedAt).toLocaleTimeString(); switch (baseline.reason) { case "opened": return `opened ${time}`; case "machine-landing": return `Claude landed ${time}`; case "pinned": return `pinned ${time}`; } } /** * Test-facing (§6.4): is this doc's baseline diff currently open in any tab * group? The diff's `modified` side is the document's own file: URI. */ isDiffOpen(docPath: string): boolean { return this.findDiffTab(vscode.Uri.file(path.join(this.rootDir, docPath))) !== undefined; } - [ ] **Step 2: Make the toggle method's signature match its registration** `toggle` is now `async` (returns `Promise`). The command registration in the constructor is `() => this.toggle(vscode.window.activeTextEditor)` — a void-returning arrow that ignores the promise, which is fine for `registerCommand`. No change needed there. - [ ] **Step 3: Typecheck + build** Run: `npm run typecheck` Expected: no errors. Run: `npm run build` Expected: succeeds. - [ ] **Step 4: Commit** ```bash git add src/diffViewController.ts git commit -m "feat(f6): toggle UX — vscode.diff open/close via tab groups (SLICE-3) F6 §6.5 PUC-1. Detects the baseline diff tab (original scheme cowriting-baseline, modified == the doc) to close-and-reveal; else opens vscode.diff with an epoch title. Live document on the right — editor state preserved by construction." ``` --- ## Task 5: Wire `DiffViewController` into the extension — SLICE-3 **Files:** - Modify: `src/extension.ts` - [ ] **Step 1: Import the controller and the store** At the top of `src/extension.ts`, after the existing imports (e.g. after `import { VersionGuard } from "./versionGuard";`), add: ```typescript import { BaselineStore } from "./baselineStore"; import { DiffViewController } from "./diffViewController"; ``` - [ ] **Step 2: Add `diffViewController` to the API type** In the `CowritingApi` interface, add the field: ```typescript export interface CowritingApi { threadController: ThreadController; attributionController: AttributionController; proposalController: ProposalController; versionGuard: VersionGuard; diffViewController: DiffViewController; } ``` - [ ] **Step 3: Add the two new commands to the no-folder stub list** In the `if (!root) { ... }` block, the stub `for` loop lists the commands. Add the two F6 commands to that array: ```typescript for (const command of [ "cowriting.createThread", "cowriting.reply", "cowriting.resolveThread", "cowriting.reopenThread", "cowriting.editSelection", "cowriting.toggleAttribution", "cowriting.applyAgentEdit", "cowriting.acceptProposal", "cowriting.rejectProposal", "cowriting.proposeAgentEdit", "cowriting.toggleDiffView", "cowriting.pinDiffBaseline", ]) { context.subscriptions.push(vscode.commands.registerCommand(command, stub)); } ``` - [ ] **Step 4: Construct the store + controller after the ProposalController block** After the `proposalController` is constructed and pushed (around line 84), add: ```typescript // --- F6: diff-view toggle (Feature #17) --- // Baseline lives in VS Code workspace storage, never the repo (INV-19). // storageUri can be undefined in odd host states → in-memory fallback (§6.5). const storageDir = context.storageUri?.fsPath; const baselineStore = storageDir ? new BaselineStore(storageDir) : null; const diffViewController = new DiffViewController(baselineStore, root); context.subscriptions.push(diffViewController); // The seam's single machine-landing signal advances the baseline (INV-18). context.subscriptions.push( attributionController.onDidApplyAgentEdit((e) => diffViewController.advance(e.document)), ); ``` - [ ] **Step 5: Capture the baseline on first sight in `renderIfOpen`** The `renderIfOpen` function currently reads: ```typescript const renderIfOpen = (doc: vscode.TextDocument) => { if (doc.uri.scheme === "file" && doc.uri.fsPath.startsWith(root)) { threadController.renderAll(doc); attributionController.loadAll(doc); proposalController.renderAll(doc); } }; ``` Add the `ensureBaseline` call inside the guard: ```typescript const renderIfOpen = (doc: vscode.TextDocument) => { if (doc.uri.scheme === "file" && doc.uri.fsPath.startsWith(root)) { threadController.renderAll(doc); attributionController.loadAll(doc); proposalController.renderAll(doc); diffViewController.ensureBaseline(doc); } }; ``` - [ ] **Step 6: Return the controller in the API** The final `return` of `activate` currently reads: ```typescript return { threadController, attributionController, proposalController, versionGuard }; ``` Change it to: ```typescript return { threadController, attributionController, proposalController, versionGuard, diffViewController }; ``` - [ ] **Step 7: Typecheck + build** Run: `npm run typecheck` Expected: no errors. Run: `npm run build` Expected: succeeds. - [ ] **Step 8: Commit** ```bash git add src/extension.ts git commit -m "feat(f6): wire DiffViewController into activation (SLICE-3) F6 §6.2. BaselineStore from context.storageUri (in-memory fallback), advance subscribed to the seam's onDidApplyAgentEdit, ensureBaseline on first sight in renderIfOpen, diffViewController on the CowritingApi, commands stubbed in the no-folder path (#8 precedent)." ``` --- ## Task 6: `package.json` contributions — commands + keybinding — SLICE-3 **Files:** - Modify: `package.json` - [ ] **Step 1: Contribute the two commands** In `contributes.commands`, after the last entry (`cowriting.proposeAgentEdit`), add: ```json { "command": "cowriting.toggleDiffView", "title": "Cowriting: Toggle Diff View", "category": "Cowriting" }, { "command": "cowriting.pinDiffBaseline", "title": "Cowriting: Pin Diff Baseline to Now", "category": "Cowriting" } ``` - [ ] **Step 2: Contribute the keybinding** Add a `keybindings` array inside `contributes` (sibling of `commands` and `menus`): ```json "keybindings": [ { "command": "cowriting.toggleDiffView", "key": "ctrl+alt+d", "when": "editorTextFocus" } ] ``` > Both commands stay palette-visible (no `commandPalette` `when: false` entry — unlike the internal seam commands). `ctrl+alt+d` is unbound in stock VS Code and user-remappable (§6.7). - [ ] **Step 3: Verify the JSON is valid and the build still runs** Run: `node -e "JSON.parse(require('fs').readFileSync('package.json','utf8')); console.log('package.json OK')"` Expected: `package.json OK`. Run: `npm run build` Expected: succeeds. - [ ] **Step 4: Commit** ```bash git add package.json git commit -m "feat(f6): contribute toggleDiffView + pinDiffBaseline commands + ctrl+alt+d (SLICE-3) F6 §5/§6.4. Palette-visible commands; ctrl+alt+d (when editorTextFocus), unbound in stock VS Code, user-remappable." ``` --- ## Task 7: Host E2E suite — SLICE-4 **Files:** - Create: `test/e2e/fixtures/workspace/docs/diffview.md` - Create: `test/e2e/suite/diffView.test.ts` The suite OWNS `docs/diffview.md` (disjoint from sample/attrib/proposal/crossrung — the F2–F5 fixture-disjointness rule). It drives the same programmatic seam ingress the proposals suite uses (`cowriting.proposeAgentEdit` + `acceptById`) — no LLM. - [ ] **Step 1: Create the fixture document** Create `test/e2e/fixtures/workspace/docs/diffview.md`: ```markdown # Diff view fixture The baseline opening paragraph stays put so the diff suite can anchor on it. A target sentence Claude will rewrite via the seam. A closing paragraph for the operator to edit by hand. ``` - [ ] **Step 2: Write the E2E suite** Create `test/e2e/suite/diffView.test.ts`: ```typescript import * as assert from "assert"; import * as fs from "fs"; import * as path from "path"; import * as vscode from "vscode"; import type { CowritingApi } from "../../../src/extension"; const WS = process.env.E2E_WORKSPACE!; const DOC_REL = "docs/diffview.md"; async function openDoc(): Promise { const uri = vscode.Uri.file(path.join(WS, DOC_REL)); const doc = await vscode.workspace.openTextDocument(uri); await vscode.window.showTextDocument(doc); return doc; } async function getApi(): Promise { const ext = vscode.extensions.getExtension("benstull.vscode-cowriting-plugin")!; const api = (await ext.activate()) as CowritingApi; assert.ok(api?.diffViewController, "extension exports diffViewController"); return api; } const settle = () => new Promise((r) => setTimeout(r, 300)); // Order-dependent (F2–F4 pattern): later tests consume earlier state. Owns // docs/diffview.md exclusively. suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", () => { const TARGET = "A target sentence Claude will rewrite via the seam."; const REPLACEMENT = "A SENTENCE CLAUDE REWROTE via the seam."; test("opening a tracked doc captures an `opened` baseline equal to the buffer (INV-18)", async () => { const doc = await openDoc(); const api = await getApi(); // renderIfOpen on open already called ensureBaseline; assert it captured. const baseline = api.diffViewController.getBaseline(DOC_REL); assert.ok(baseline, "baseline captured on first sight"); assert.strictEqual(baseline!.reason, "opened"); assert.strictEqual(baseline!.text, doc.getText(), "baseline = open-time buffer"); }); test("toggle opens a diff tab (original scheme cowriting-baseline) over the live doc (PUC-1)", async () => { const api = await getApi(); assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "no diff open yet"); await vscode.commands.executeCommand("cowriting.toggleDiffView"); await settle(); assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff tab open"); // The active tab is a TextDiff whose original is the baseline scheme. const active = vscode.window.tabGroups.activeTabGroup.activeTab; assert.ok(active && active.input instanceof vscode.TabInputTextDiff, "active tab is a diff"); assert.strictEqual( (active!.input as vscode.TabInputTextDiff).original.scheme, "cowriting-baseline", "left side served by the baseline provider", ); }); test("typing leaves the baseline unchanged while the buffer diverges", async () => { const doc = await openDoc(); const api = await getApi(); const before = api.diffViewController.getBaseline(DOC_REL)!.text; const edit = new vscode.WorkspaceEdit(); edit.insert(doc.uri, new vscode.Position(0, 0), "OPERATOR ADDED LINE\n"); assert.ok(await vscode.workspace.applyEdit(edit), "operator edit applied"); await settle(); assert.strictEqual(api.diffViewController.getBaseline(DOC_REL)!.text, before, "baseline unchanged by typing"); assert.notStrictEqual(doc.getText(), before, "buffer diverged"); }); test("accepting a proposal advances the baseline past the landed text (PUC-2, INV-18)", async () => { const doc = await openDoc(); const api = await getApi(); const start = doc.getText().indexOf(TARGET); assert.ok(start >= 0, "fixture contains the target"); const id = await vscode.commands.executeCommand("cowriting.proposeAgentEdit", { uri: doc.uri.toString(), start, end: start + TARGET.length, newText: REPLACEMENT, model: "sonnet", sessionId: "e2e-diff", turnId: "turn-d1", }); assert.ok(id, "propose returns an id"); assert.ok(await api.proposalController.acceptById(DOC_REL, id!), "accept applies via the seam"); await settle(); const baseline = api.diffViewController.getBaseline(DOC_REL)!; assert.strictEqual(baseline.reason, "machine-landing", "baseline advanced on the landing"); assert.ok(baseline.text.includes(REPLACEMENT), "landed text is in the baseline (won't show as a change)"); assert.ok(!baseline.text.includes(TARGET), "old target gone from the baseline too"); assert.strictEqual(baseline.text, doc.getText(), "baseline == buffer right after the landing"); }); test("an operator edit after the landing makes baseline ≠ buffer (the operator delta)", async () => { const doc = await openDoc(); const api = await getApi(); const edit = new vscode.WorkspaceEdit(); edit.insert(doc.uri, new vscode.Position(0, 0), "POST-LANDING OPERATOR LINE\n"); assert.ok(await vscode.workspace.applyEdit(edit)); await settle(); assert.notStrictEqual( api.diffViewController.getBaseline(DOC_REL)!.text, doc.getText(), "operator changes show against the advanced baseline", ); }); test("pin resets the baseline to now: baseline == buffer, reason pinned (PUC-3)", async () => { const doc = await openDoc(); const api = await getApi(); await vscode.commands.executeCommand("cowriting.pinDiffBaseline"); await settle(); const baseline = api.diffViewController.getBaseline(DOC_REL)!; assert.strictEqual(baseline.reason, "pinned"); assert.strictEqual(baseline.text, doc.getText(), "pinned baseline == current buffer (diff empties)"); }); test("the baseline is persisted on disk under the storage dir with the expected content (PUC-4)", async () => { const api = await getApi(); const p = api.diffViewController.baselineFilePath(DOC_REL); assert.ok(p, "storage-backed baseline path is available"); assert.ok(fs.existsSync(p!), `baseline file exists at ${p}`); const onDisk = JSON.parse(fs.readFileSync(p!, "utf8")); assert.strictEqual(onDisk.docPath, DOC_REL); assert.strictEqual(onDisk.reason, "pinned", "last epoch (pin) persisted"); assert.strictEqual(onDisk.text, api.diffViewController.getBaseline(DOC_REL)!.text, "on-disk == in-memory"); // INV-19: nothing leaked into the repo's .threads sidecar tree. assert.ok(!p!.includes(`${path.sep}.threads${path.sep}`), "baseline is NOT in the sidecar tree"); }); test("toggle again closes the diff tab and reveals the normal editor (PUC-1)", async () => { const api = await getApi(); if (!api.diffViewController.isDiffOpen(DOC_REL)) { await vscode.commands.executeCommand("cowriting.toggleDiffView"); await settle(); } assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff open before close"); await vscode.commands.executeCommand("cowriting.toggleDiffView"); await settle(); assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "diff tab closed"); const active = vscode.window.tabGroups.activeTabGroup.activeTab; assert.ok( active && active.input instanceof vscode.TabInputText, "a normal text editor tab is active after closing the diff", ); }); test("toggling on an untracked doc warns and opens no diff (PUC-5)", async () => { const api = await getApi(); const untracked = await vscode.workspace.openTextDocument({ content: "scratch", language: "markdown" }); await vscode.window.showTextDocument(untracked); await settle(); await vscode.commands.executeCommand("cowriting.toggleDiffView"); await settle(); // No baseline-diff tab for an untitled doc anywhere. const anyDiff = vscode.window.tabGroups.all.some((g) => g.tabs.some( (t) => t.input instanceof vscode.TabInputTextDiff && t.input.original.scheme === "cowriting-baseline" && t.input.modified.toString() === untracked.uri.toString(), ), ); assert.strictEqual(anyDiff, false, "no diff opened for the untracked doc"); }); }); ``` - [ ] **Step 3: Run the host E2E** Run: `npm run test:e2e` Expected: PASS — the new F6 suite green alongside the existing threads/attribution/proposals/crossrung suites; the no-workspace pass runs after (updated in Task 8). > If a timing flake appears (tab not yet registered), bump that test's `settle()` once — the F2–F5 suites use the same 300ms settle. - [ ] **Step 4: Commit** ```bash git add test/e2e/fixtures/workspace/docs/diffview.md test/e2e/suite/diffView.test.ts git commit -m "test(f6): host E2E — toggle, advance-on-accept, pin, persist, untracked (SLICE-4) F6 §6.8. Drives the programmatic seam ingress (propose + accept, no LLM): opened baseline → toggle opens cowriting-baseline diff → type (baseline steady) → accept advances past the landing (INV-18) → operator delta → pin → on-disk baseline outside .threads (INV-19) → toggle closes → untracked warns." ``` --- ## Task 8: Update the no-workspace stub regression — SLICE-4 **Files:** - Modify: `test/e2e/suite-no-workspace/noWorkspace.test.ts` - [ ] **Step 1: Add the two F6 commands to the stub-registration assertion** In the `for` loop listing commands that must be registered as stubs, add the two F6 commands: ```typescript for (const command of [ "cowriting.createThread", "cowriting.reply", "cowriting.resolveThread", "cowriting.reopenThread", "cowriting.editSelection", "cowriting.toggleAttribution", "cowriting.applyAgentEdit", "cowriting.acceptProposal", "cowriting.rejectProposal", "cowriting.proposeAgentEdit", "cowriting.toggleDiffView", "cowriting.pinDiffBaseline", ]) { assert.ok(all.includes(command), `${command} is registered`); } ``` - [ ] **Step 2: Run the host E2E (both passes)** Run: `npm run test:e2e` Expected: PASS — including the no-workspace second pass asserting the two new stubs exist. - [ ] **Step 3: Commit** ```bash git add test/e2e/suite-no-workspace/noWorkspace.test.ts git commit -m "test(f6): assert toggleDiffView + pinDiffBaseline are no-folder stubs (#8, SLICE-4)" ``` --- ## Task 9: Manual smoke doc + README pointer — SLICE-4 **Files:** - Create: `docs/MANUAL-SMOKE-F6.md` - Modify: `README.md` - [ ] **Step 1: Write the manual smoke doc** Create `docs/MANUAL-SMOKE-F6.md`: ```markdown # Manual smoke — F6 diff-view toggle (live) Pre-req: a real machine (not CI). Step 4 uses a live Claude turn — Claude Code installed + signed in (the `claude-code` provider rides that login, INV-8). The rest of F6 needs no credentials and no network. 1. `npm run build`, launch the extension (F5 in VS Code opens the committed `sandbox/` playground), open `playground.md`. 2. Edit a sentence by hand, then **Cmd/Ctrl-Alt-D** (or run **Cowriting: Toggle Diff View**). ✅ A diff opens: the readonly baseline on the left, your live document on the right; the tab title reads `playground.md — my changes since opened