fix(proposals): reload-safe optimisticApply + reconciled toolbar summary (#64)

Final-review fixes:
- CRITICAL: optimisticApply no longer re-captures `original` from an
  already-applied buffer after a window reload (in-memory `applied` set is
  empty post-reload). A proposal already carrying `original` is marked applied
  and skipped, so Reject's revert target survives save+reload (INV-51/54).
  Adds a reload-safety host-E2E that reproduces the prior-session state.
- MINOR: the preview toolbar +N/-N summary now counts against the landed text
  (current minus pending proposals) via the new pure landedTextOf(), so a
  pending change is shown once (as a proposal), not double-counted (INV-50).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/proposalController.ts

@@ -315,6 +315,17 @@ export class ProposalController implements vscode.Disposable {
     const proposal = state.artifact.proposals.find((p) => p.id === proposalId);
     const fp = proposal ? state.artifact.anchors[proposal.anchorId]?.fingerprint : undefined;
     if (!proposal || !fp) return false;
+    // Reload-safety (INV-51/54): a proposal that already carries `original` was
+    // optimistically applied in a PRIOR session — the buffer holds the applied text
+    // and `fp` points at it, but this (fresh) controller's in-memory `applied` set is
+    // empty. Re-applying would recapture `original` from the already-applied buffer
+    // (= the replacement) and CLOBBER the true revert target, breaking Reject. Mark it
+    // applied in memory and stop — `original` is captured exactly once, on first apply.
+    if (proposal.original !== undefined) {
+      state.applied.add(proposalId);
+      this.renderAll(document);
+      return true;
+    }
     const resolved = resolve(document.getText(), fp);
     if (resolved === "orphaned") return false;
     const original = document.getText(

src/trackChangesModel.ts

@@ -791,6 +791,26 @@ function renderReviewOp(
  * INV-34). Deterministic: proposals in the same block are ordered by anchorStart
  * then id; trailing proposals keep input order.
  */
+/**
+ * F12/#64 (INV-50): `currentText` with every resolved pending proposal's applied
+ * span reverted to its original (`replaced`) — the "landed" text the baseline diff
+ * should run against, so a pending proposal renders ONCE (as a proposal), never also
+ * as a landed change. Reverts high→low so earlier offsets stay valid. Pure. The
+ * preview's summary tally diffs against this too, so the toolbar count matches the
+ * body (a pending change is not double-counted as both a landed add/remove and a
+ * proposal).
+ */
+export function landedTextOf(currentText: string, proposals: ProposalView[]): string {
+  const pendingApplied = proposals
+    .filter((p) => p.anchorStart !== null)
+    .sort((a, b) => b.anchorStart! - a.anchorStart!);
+  let landedText = currentText;
+  for (const p of pendingApplied) {
+    landedText = landedText.slice(0, p.anchorStart!) + p.replaced + landedText.slice(p.anchorEnd!);
+  }
+  return landedText;
+}
+
 export function renderReview(
   baselineText: string,
   currentText: string,
@@ -802,16 +822,12 @@ export function renderReview(
 
   // F12/#64 (INV-50): with optimistic apply the proposed text is already in
   // `currentText`, so a naive baseline→current diff would render each proposed
-  // change BOTH as a landed diff and as its proposal block. Diff against
-  // `currentText` with every resolved pending proposal reverted to its original,
-  // so the landed diff excludes pending proposals; they render once, as proposals.
+  // change BOTH as a landed diff and as its proposal block. Diff against the
+  // "landed" text (current minus pending proposals) so they render once.
   const pendingApplied = proposals
     .filter((p) => p.anchorStart !== null)
     .sort((a, b) => b.anchorStart! - a.anchorStart!);
-  let landedText = currentText;
-  for (const p of pendingApplied) {
-    landedText = landedText.slice(0, p.anchorStart!) + p.replaced + landedText.slice(p.anchorEnd!);
-  }
+  const landedText = landedTextOf(currentText, proposals);
 
   const ranges = splitBlocksWithRanges(landedText);
   const ops = diffBlocks(baselineText, landedText);

src/trackChangesPreview.ts

@@ -13,7 +13,7 @@ import * as vscode from "vscode";
 import type { DiffViewController } from "./diffViewController";
 import type { AttributionController } from "./attributionController";
 import type { ProposalController } from "./proposalController";
-import { renderReview, renderPlain, diffBlocks, diffToBlockHunks, type BlockOp } from "./trackChangesModel";
+import { renderReview, renderPlain, diffBlocks, diffToBlockHunks, landedTextOf, type BlockOp } from "./trackChangesModel";
 import { buildFingerprint } from "./anchorer";
 import { isAuthorable } from "./workspacePath";
 import type { EditTurnResult, RunEditTurnOptions } from "./liveTurn";
@@ -382,9 +382,13 @@ export class TrackChangesPreviewController implements vscode.Disposable {
     }
     const spans = this.attribution.spansFor(document);
     const proposals = this.proposals.listProposals(document);
+    // F12/#64 (INV-50): count added/removed against the LANDED text (current minus
+    // pending proposals), matching the body — a pending change shows once, as a
+    // proposal, and is not also tallied as a landed add/remove.
+    const landedOps = diffBlocks(baselineText, landedTextOf(current, proposals));
     const summary = {
-      added: ops.filter((o) => o.kind === "added").length,
-      removed: ops.filter((o) => o.kind === "removed").length,
+      added: landedOps.filter((o) => o.kind === "added").length,
+      removed: landedOps.filter((o) => o.kind === "removed").length,
       proposals: proposals.length,
     };
     void panel.webview.postMessage({

test/e2e/suite/f12InlineDiff.test.ts

@@ -3,6 +3,8 @@ import * as fs from "fs";
 import * as path from "path";
 import * as vscode from "vscode";
 import type { CowritingApi } from "../../../src/extension";
+import { addProposal, setProposalApplied } from "../../../src/proposalModel";
+import { buildFingerprint } from "../../../src/anchorer";
 
 const WS = process.env.E2E_WORKSPACE!;
 const settle = () => new Promise((r) => setTimeout(r, 400));
@@ -197,3 +199,53 @@ suite("F12 inline diff — control parity (#64, INV-53)", () => {
     assert.ok(entry && /editorLangId == markdown/.test(entry.when ?? ""), "palette-guarded on markdown");
   });
 });
+
+// Reload-safety: a proposal that was optimistically applied in a PRIOR session
+// persists with `original` set and its fp re-anchored to the applied text. A fresh
+// controller (empty in-memory `applied` set) must NOT re-capture `original` from the
+// already-applied buffer — doing so would clobber the true revert target and break
+// Reject. (Regression for the final-review CRITICAL; INV-51/54.)
+suite("F12 inline diff — reload-safety (#64, INV-51/54)", () => {
+  test("optimisticApply does not clobber a previously-persisted original", async () => {
+    const TRUE_ORIGINAL = "The original sentence here.";
+    const APPLIED = "The APPLIED sentence here.";
+    const { doc } = await freshDoc("docs/f12-reload.md", `# R\n\n${TRUE_ORIGINAL}\n`);
+    const api = await getApi();
+    const p = api.proposalController;
+    const key = p.keyFor(doc);
+
+    // 1) The buffer holds the APPLIED text (as the saved-while-pending file would).
+    const at = doc.getText().indexOf(TRUE_ORIGINAL);
+    const we = new vscode.WorkspaceEdit();
+    we.replace(doc.uri, new vscode.Range(doc.positionAt(at), doc.positionAt(at + TRUE_ORIGINAL.length)), APPLIED);
+    assert.ok(await vscode.workspace.applyEdit(we), "apply the prior-session applied text");
+    await settle();
+
+    // 2) Record the proposal directly in the sidecar exactly as a prior session left
+    //    it: fp anchored to the APPLIED text + `original` = the TRUE original. We do
+    //    NOT call optimisticApply, so this controller's in-memory `applied` stays empty.
+    const appliedAt = doc.getText().indexOf(APPLIED);
+    const appliedFp = buildFingerprint(doc.getText(), { start: appliedAt, end: appliedAt + APPLIED.length });
+    let id = "";
+    api.sidecarRouter.update(key, (a) => {
+      id = addProposal(a, appliedFp, APPLIED, { kind: "agent", id: "claude", agent: { sdk: "x", model: "m", sessionId: "s" } }, { granularity: "block" }).proposalId;
+      setProposalApplied(a, id, appliedFp, TRUE_ORIGINAL);
+    });
+    p.renderAll(doc);
+    await settle();
+
+    // 3) Re-entry as a reload would trigger (EditorProposalController re-applies on
+    //    onDidChangeProposals because `applied` is empty). The guard must preserve original.
+    await p.optimisticApply(doc, id);
+    await settle();
+    const view = p.listProposals(doc).find((v) => v.id === id);
+    assert.ok(view, "proposal still present");
+    assert.strictEqual(view!.original, TRUE_ORIGINAL, "true original preserved, NOT clobbered with the applied text");
+
+    // 4) Reject restores the TRUE original (not the applied text).
+    assert.ok(await p.revertInPlace(key, id), "revert");
+    await settle();
+    assert.ok(doc.getText().includes(TRUE_ORIGINAL), "reject restored the true original");
+    assert.ok(!doc.getText().includes(APPLIED), "applied text removed on reject");
+  });
+});