src/trackChangesModel.ts

@@ -441,6 +441,14 @@ function wordMergedMarkdown(beforeRaw: string, afterRaw: string): string {
 export interface RenderOptions {
   /** Per-block markdown→HTML renderer (test seam). Defaults to the bundled markdown-it. */
   render?: (src: string) => string;
+  /**
+   * #48: the baseline was just PINNED (`reason === "pinned"`). With zero changes
+   * since that pin, the on-render is fully clean — no authorship coloring — so a
+   * pin reads as "this is my clean starting point". Distinct from a baseline
+   * advanced by a machine-landing (accept), which keeps its authorship coloring
+   * (F10 INV-33). Only consulted by `renderReview`.
+   */
+  pinned?: boolean;
 }
 
 function defaultRender(src: string): string {
@@ -673,6 +681,14 @@ export function renderReview(
   const render = opts.render ?? defaultRender;
   const ranges = splitBlocksWithRanges(currentText);
   const ops = diffBlocks(baselineText, currentText);
+  // #48: right after a PIN (baseline reason "pinned") with no changes since, the
+  // panel is fully clean: no change marks (already absent) AND no authorship
+  // coloring, so the pin reads as "this is my clean starting point". Skip
+  // colorByAuthor for every block in this case; data-src mapping and any pending
+  // proposals (review actions, not annotations) are kept below. A baseline advanced
+  // by a machine-landing (accept) is ALSO zero-diff but is NOT pinned — it keeps
+  // its authorship coloring (F10 INV-33), so this is gated on the pin specifically.
+  const clean = opts.pinned === true && ops.every((o) => o.kind === "unchanged");
 
   // Associate each resolved proposal with the current-side block index whose range
   // it anchors into: the largest block with start <= anchorStart (the containing
@@ -703,7 +719,7 @@ export function renderReview(
     const blockIndex = op.kind === "removed" ? -1 : ci;
     const blk = op.kind === "removed" ? undefined : ranges[ci++];
     const colored = (raw: string): string =>
-      blk ? colorByAuthor(raw, blk.start, authorSpans, render) : render(raw);
+      blk && !clean ? colorByAuthor(raw, blk.start, authorSpans, render) : render(raw);
     bodyParts.push(renderReviewOp(op, render, colored, srcAttr(blk)));
     const here = blockIndex >= 0 ? byBlock.get(blockIndex) : undefined;
     if (here) for (const p of here) bodyParts.push(proposalBlockHtml(p, render));

src/trackChangesPreview.ts

@@ -337,7 +337,7 @@ export class TrackChangesPreviewController implements vscode.Disposable {
     void panel.webview.postMessage({
       type: "render",
       mode,
-      html: renderReview(baselineText, current, spans, proposals),
+      html: renderReview(baselineText, current, spans, proposals, { pinned: baseline?.reason === "pinned" }),
       epoch: this.epochLabel(baseline),
       summary,
       authorable,
@@ -464,6 +464,7 @@ export class TrackChangesPreviewController implements vscode.Disposable {
       current,
       this.attribution.spansFor(doc),
       this.proposals.listProposals(doc),
+      { pinned: baseline?.reason === "pinned" },
     );
   }
   /** F10: current annotations mode for a panel (default on). */

test/e2e/suite/s48PinClean.test.ts

@@ -0,0 +1,63 @@
+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 settle = () => new Promise((r) => setTimeout(r, 400));
+
+async function getApi(): Promise<CowritingApi> {
+  const ext = vscode.extensions.getExtension("benstull.vscode-cowriting-plugin")!;
+  const api = (await ext.activate()) as CowritingApi;
+  assert.ok(api?.trackChangesPreviewController, "exports preview controller");
+  return api;
+}
+
+async function freshDoc(rel: string, body: string): Promise<{ doc: vscode.TextDocument; key: string }> {
+  const abs = path.join(WS, rel);
+  fs.mkdirSync(path.dirname(abs), { recursive: true });
+  fs.writeFileSync(abs, body, "utf8");
+  const uri = vscode.Uri.file(abs);
+  const doc = await vscode.workspace.openTextDocument(uri);
+  await vscode.window.showTextDocument(doc);
+  await settle();
+  return { doc, key: uri.toString() };
+}
+
+// #48 host E2E (no LLM): pinning the baseline leaves the review panel fully clean
+// — no authorship coloring on unchanged blocks — while re-divergence brings the
+// annotations back. The author colors are read from the on-state renderReview HTML.
+suite("S48 — pin → fully clean review panel (host E2E, no LLM)", () => {
+  test("pin clears authorship coloring; a later edit brings annotations back", async () => {
+    const { doc, key } = await freshDoc("docs/s48pin.md", "# S48\n\nAn original baseline paragraph.\n");
+    const api = await getApi();
+    const ctl = api.trackChangesPreviewController;
+    await vscode.commands.executeCommand("cowriting.showTrackChangesPreview");
+    await settle();
+
+    // Type a paragraph → a human attribution span + author coloring in the on-state.
+    const edit = new vscode.WorkspaceEdit();
+    edit.insert(doc.uri, doc.positionAt(doc.getText().length), "\n\nA freshly typed human paragraph.\n");
+    assert.ok(await vscode.workspace.applyEdit(edit), "operator edit applied");
+    await settle();
+    assert.match(ctl.renderHtmlFor(key), /cw-by-human/, "typed text is author-colored before the pin");
+
+    // Pin the baseline → zero diff → the panel must be fully clean.
+    ctl.receiveMessage(key, { type: "pinBaseline" });
+    await settle();
+    const pinned = ctl.renderHtmlFor(key);
+    assert.ok(!pinned.includes("cw-by-human"), "no human authorship coloring after pin");
+    assert.ok(!pinned.includes("cw-by-claude"), "no Claude authorship coloring after pin");
+    assert.ok(!pinned.includes("cw-add") && !pinned.includes("cw-del"), "no change marks after pin");
+    assert.match(pinned, /data-src-start/, "blocks still carry data-src offsets (INV-36 mapping kept)");
+    assert.ok(pinned.includes("freshly typed human paragraph"), "the body text is still rendered, just plain");
+
+    // Edit again → there are changes since the pinned baseline → annotations return.
+    const edit2 = new vscode.WorkspaceEdit();
+    edit2.insert(doc.uri, doc.positionAt(doc.getText().length), "\n\nA second typed paragraph diverges again.\n");
+    assert.ok(await vscode.workspace.applyEdit(edit2), "second operator edit applied");
+    await settle();
+    assert.match(ctl.renderHtmlFor(key), /cw-by-human/, "authorship coloring returns once the doc diverges from the pin");
+  });
+});

test/trackChangesModel.test.ts

@@ -277,6 +277,54 @@ describe("renderReview", () => {
     expect(uIdx).toBeGreaterThan(html.indexOf("Beta there")); // unanchored still trails the body
     expect(html).toContain("cw-proposal-unanchored");
   });
+  // #48: a PINNED baseline with zero changes leaves the panel fully un-annotated —
+  // no authorship coloring on unchanged blocks — while pending proposals still show.
+  test("renderReview: pinned + zero diff with author spans renders NO authorship coloring", () => {
+    const doc = "Human wrote this.\n\nClaude wrote that.";
+    const spans: AuthorSpan[] = [
+      { start: 0, end: 17, author: "human" },
+      { start: 19, end: doc.length, author: "claude" },
+    ];
+    const html = renderReview(doc, doc, spans, [], { pinned: true });
+    expect(html).not.toContain("cw-by-human");
+    expect(html).not.toContain("cw-by-claude");
+    expect(html).not.toContain("cw-add");
+    expect(html).not.toContain("cw-del");
+    // still a selection→source surface (INV-36): blocks carry data-src offsets.
+    expect(html).toContain("data-src-start");
+    // the body text is still there, just plain.
+    expect(html).toContain("Human wrote this.");
+    expect(html).toContain("Claude wrote that.");
+  });
+  test("renderReview: pinned + zero diff still renders a pending proposal block", () => {
+    const doc = "Human wrote this.\n\nClaude wrote that.";
+    const spans: AuthorSpan[] = [{ start: 0, end: 17, author: "human" }];
+    const proposals: ProposalView[] = [
+      { id: "p1", anchorStart: 0, anchorEnd: 5, replaced: "Human", replacement: "Person" },
+    ];
+    const html = renderReview(doc, doc, spans, proposals, { pinned: true });
+    expect(html).not.toContain("cw-by-human"); // body still clean
+    expect(html).toContain('data-proposal-id="p1"'); // proposal still shows (it is an action)
+    expect(html).toContain("Person");
+  });
+  test("renderReview: zero diff WITHOUT a pin (e.g. machine-landing) keeps authorship coloring (INV-33)", () => {
+    // accepting a Claude edit advances the baseline (zero diff) but is NOT a pin —
+    // the landed author coloring must remain.
+    const doc = "Human wrote this.\n\nClaude wrote that.";
+    const spans: AuthorSpan[] = [{ start: 19, end: doc.length, author: "claude" }];
+    const html = renderReview(doc, doc, spans, []); // no pinned flag
+    expect(html).toContain("cw-by-claude");
+  });
+  test("renderReview: with REAL changes since a pin, author coloring returns", () => {
+    // a genuine added block is still author-colored even when pinned (only the
+    // zero-diff-after-pin state is clean).
+    const baseline = "Hello world";
+    const current = "Hello world\n\nHello world";
+    const spans: AuthorSpan[] = [{ start: 19, end: 24, author: "human" }];
+    const html = renderReview(baseline, current, spans, [], { pinned: true });
+    expect((html.match(/cw-by-human/g) ?? []).length).toBe(1);
+  });
+
   test("renderReview is deterministic with mixed anchored/unanchored proposals", () => {
     const doc = "one two three";
     const proposals: ProposalView[] = [