#40 (WIP, UNVERIFIED): restore exact author attribution on undo/redo

Follow-up to #38. #38 made undo/redo re-inserted text neutral (no false human
coloring); #40 restores its EXACT prior attribution so Claude's restored text is
blue again, the human's green.

Mechanism — text-keyed attribution snapshots: per-doc Map<documentText, spans>,
snapshotted after every forward edit + at load; on undo/redo, after the #38
geometry reconcile, if a snapshot's text equals the current buffer the spans are
restored exactly (offsets valid — identical text). Robust to VS Code undo
coalescing (only the resulting-text-matching event restores); far-back/evicted
states fall back to #38 neutral. History bounded (ATTR_HISTORY_MAX, oldest
evicted).

NOT MERGED / NOT VERIFIED END-TO-END: 222 unit + typecheck green, but the #40
host E2E (and the pre-existing #38 undoMarks E2E) depend on
executeCommand("undo"), which is broken in this test environment — the untouched
#38 test fails identically on clean main (the known undoMarks flake, now
deterministic). Clearing .vscode-test/user-data (the usual remedy) is
permission-blocked here. The operator should verify in a working E2E environment
before merging.

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

sessions/0048/SESSION-0048.0-TRANSCRIPT-2026-06-13T08-45--2026-06-13T08-58.md

@@ -1,90 +0,0 @@
-# Session 0048.0 — Transcript
-
-> App: vscode-cowriting-plugin
-> Start: 2026-06-13T08-45 (PST)
-> Type: planning-and-executing
-> End: 2026-06-13T08-58 (PST)
-> Status: **FINALIZED.**
-> Posture: autonomous (yolo)
-
-## Launch prompt
-
-```
-/goal plan-and-execute #40 (restore exact author attribution on undo/redo — follow-up to #38)
-
-```
-
-## Plan
-
-**#40 (task, P3)** — restore exact author attribution on undo/redo (follow-up to
-#38). Anchor: leaf `task` → §4.3 R2 (no design gate). Picked autonomously (last
-R2-eligible leaf not blocked by a content-repo/careful/irreversible gate).
-
-#38 made undo/redo re-inserted text **neutral** (no false human coloring) but
-lossy: undoing a deletion of Claude text shows it neutral, not blue. #40 restores
-the **exact prior** attribution.
-
-**Mechanism (engineering choice): text-keyed attribution snapshots.** Per-doc
-`Map<documentText, spans>`; snapshot after every FORWARD edit (and at load). On
-undo/redo, after the #38 geometry reconcile, if a snapshot's text equals the
-current buffer, restore those spans exactly (offsets valid — text identical).
-Robust to VS Code undo coalescing (only the event whose resulting text matches a
-snapshot restores; far-back/evicted states fall back to #38 neutral). Bounded
-history.
-
-Tasks: snapshot+restore in `attributionController` (loadAll + onDidChange);
-tests (agent-text undo restores blue; edit→undo→redo round-trip; #38 regression
-green). No deploy pipeline (extension).
-
-## Results
-
-**#40 implemented but NOT shipped — verification-blocked.** On branch
-`s40-undo-provenance` (pushed, unmerged); issue #40 **kept open**.
-
-- `attributionController.ts` — text-keyed attribution snapshots
-  (`attrHistory: Map<documentText, spans>`, `ATTR_HISTORY_MAX` bounded): snapshot
-  after every forward edit + at `loadAll`; on undo/redo restore the snapshot whose
-  text equals the current buffer (else #38 neutral fallback). Robust to undo
-  coalescing.
-- `test/e2e/suite/s40Provenance.test.ts` — agent-text-undo-restores-blue +
-  edit→undo→redo round-trip.
-- **222 unit + typecheck green.**
-
-**BLOCKER (environmental, not the code):** the #40 host E2E — and the *untouched*
-#38 `undoMarks` E2E — drive `executeCommand("undo")`, which does **not restore
-text** in this local test instance. Proven by stashing all my changes and running
-clean `main`: the #38 test fails identically (`undo restored 'bravo'`). This is the
-**known undoMarks flake (session 0037), now deterministic** in this environment.
-The usual remedy — clearing `.vscode-test/user-data` — is **permission-blocked**
-this session (`rm -rf` denied). Focusing the doc before `undo` (`showTextDocument`)
-did not help. So #40's end-to-end behavior cannot be verified here; shipping
-unverified changes to the load-bearing F3 attribution controller would violate
-verify-before-completion. Left on a branch for the operator to verify + merge in a
-working E2E environment.
-
-**Also surfaced:** `main`'s E2E is currently **red in this environment** for the
-same environmental reason (the undoMarks `undo` flake) — a test-infra issue
-independent of product code.
-
-## Session arc
-
-1. Stop hook required determining/executing the next milestone; chose #40 (last
-   R2-eligible leaf). Claimed 0048, clean `main`.
-2. Read #40 + #38 + the attribution change handler; chose text-keyed snapshots.
-3. TDD: wrote #40 E2E + implemented snapshot/restore; 222 unit green.
-4. E2E: 3 undo-driven tests failed at the `undo restored X` step. Isolated by
-   stashing → clean `main`'s #38 test fails identically → environmental undo flake,
-   not my code. Could not clear `.vscode-test` (permission-blocked).
-5. Committed #40 to a branch (pushed, unmerged, marked UNVERIFIED); kept #40 open;
-   stopped per verify-before-completion.
-
-## Deferred decisions
-
-_Autonomous-mode low-confidence calls the driver made and would have
-liked operator input on. Empty if none._
-
-- **Did not merge #40** (driver call). Alternative: merge on unit-green + reasoning
-  alone. Why not: it changes the core F3 attribution controller and its behavior is
-  only meaningfully provable through an undo E2E, which is environmentally broken
-  here — verify-before-completion says don't claim/ship it. Preserved on a branch
-  for operator verification instead. (Reversible: just merge once verified.)

sessions/0048/SESSION-0048.0-TRANSCRIPT-2026-06-13T08-45--INPROGRESS.md

@@ -1,18 +1,18 @@
-# Session 0049.0 — Transcript
+# Session 0048.0 — Transcript
 
 > App: vscode-cowriting-plugin
-> Start: 2026-06-13T09-19 (PST)
+> Start: 2026-06-13T08-45 (PST)
 > Type: planning-and-executing
 > Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
 >
-> This file reserves session ID 0049 for vscode-cowriting-plugin. The driver replaces this
+> This file reserves session ID 0048 for vscode-cowriting-plugin. The driver replaces this
 > body with the full transcript and renames the file to its final
-> SESSION-0049.0-TRANSCRIPT-2026-06-13T09-19--<end>.md form at session end.
+> SESSION-0048.0-TRANSCRIPT-2026-06-13T08-45--<end>.md form at session end.
 
 ## Launch prompt
 
 ```
-/goal plan-and-execute: pretest:e2e cleans stale compiled tests in out/test (stale *.test.js from other branches were running via the glob) — build hygiene follow-up to #54
+/goal plan-and-execute #40 (restore exact author attribution on undo/redo — follow-up to #38)
 
 ```
 

sessions/sessions.json

@@ -142,8 +142,5 @@
   },
   "0048": {
     "title": ""
-  },
-  "0049": {
-    "title": ""
   }
 }

src/attributionController.ts

@@ -44,8 +44,19 @@ interface DocAttribution {
    * orphans on reload).
    */
   hadAttributions: boolean;
+  /**
+   * #40: text-keyed attribution snapshots for exact provenance restoration on
+   * undo/redo. Maps a document-text state → the live spans at that state (offsets
+   * valid for that exact text). Captured after every forward edit + at load;
+   * consulted on undo/redo to restore the matching state's spans. Bounded (oldest
+   * evicted) — a far-back/evicted state falls back to the #38 neutral reconcile.
+   */
+  attrHistory: Map<string, LiveSpan[]>;
 }
 
+/** #40: cap on the per-doc attribution-snapshot history (oldest evicted). */
+const ATTR_HISTORY_MAX = 200;
+
 export class AttributionController implements vscode.Disposable {
   private readonly disposables: vscode.Disposable[] = [];
   private readonly docs = new Map<string, DocAttribution>();
@@ -90,7 +101,7 @@ export class AttributionController implements vscode.Disposable {
   private state(docPath: string): DocAttribution {
     let s = this.docs.get(docPath);
     if (!s) {
-      s = { docPath, spans: [], orphans: [], records: new Map(), hadAttributions: false };
+      s = { docPath, spans: [], orphans: [], records: new Map(), hadAttributions: false, attrHistory: new Map() };
       this.docs.set(docPath, s);
     }
     return s;
@@ -125,6 +136,9 @@ export class AttributionController implements vscode.Disposable {
       s.spans = coalesce(s.spans);
       if (artifact.attributions.length > 0) s.hadAttributions = true;
     }
+    // #40: seed the snapshot history with the loaded state so undoing back to it
+    // restores its exact attribution.
+    this.snapshotAttribution(s, document.getText());
     this.render(document);
   }
 
@@ -140,6 +154,17 @@ export class AttributionController implements vscode.Disposable {
 
   // ---- PUC-1/PUC-3: live tracking ---------------------------------------------------
 
+  /** #40: snapshot the current spans keyed by the document's current text. */
+  private snapshotAttribution(s: DocAttribution, text: string): void {
+    s.attrHistory.delete(text); // re-insert at the end (recency order)
+    s.attrHistory.set(text, s.spans.map((sp) => ({ ...sp })));
+    while (s.attrHistory.size > ATTR_HISTORY_MAX) {
+      const oldest = s.attrHistory.keys().next().value as string | undefined;
+      if (oldest === undefined) break;
+      s.attrHistory.delete(oldest);
+    }
+  }
+
   private onDidChange(e: vscode.TextDocumentChangeEvent): void {
     if (!this.isTracked(e.document) || e.contentChanges.length === 0) return;
     const docPath = this.keyOf(e.document);
@@ -202,6 +227,18 @@ export class AttributionController implements vscode.Disposable {
         );
       }
     }
+    // #40: exact provenance across history navigation. After a FORWARD edit,
+    // snapshot the new state's spans. On UNDO/REDO, the geometry reconcile above
+    // left re-inserted text neutral (#38); if a snapshot's text equals the current
+    // buffer, restore that state's spans exactly (offsets are valid — identical
+    // text) so Claude's restored text is blue again, the human's green. No match
+    // (far-back/evicted state) keeps the #38 neutral fallback.
+    if (isUndoRedo) {
+      const restored = s.attrHistory.get(e.document.getText());
+      if (restored) s.spans = restored.map((sp) => ({ ...sp }));
+    } else {
+      this.snapshotAttribution(s, e.document.getText());
+    }
     if (s.spans.length > 0) s.hadAttributions = true;
     this.render(e.document);
   }

test/e2e/suite/s40Provenance.test.ts

@@ -0,0 +1,113 @@
+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));
+const AGENT = { kind: "agent" as const, id: "claude", agent: { sdk: "@cline/sdk", model: "sonnet", sessionId: "e2e-s40" } };
+
+async function getApi(): Promise<CowritingApi> {
+  const ext = vscode.extensions.getExtension("benstull.vscode-cowriting-plugin")!;
+  const api = (await ext.activate()) as CowritingApi;
+  assert.ok(api?.attributionController, "exports attribution");
+  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() };
+}
+
+// #40 (follow-up to #38): on undo/redo, restore each re-inserted char's EXACT
+// prior author attribution rather than leaving it neutral (#38). Driven mid-edit
+// (buffer dirty) so the attribution branch runs, not the disk-sync one.
+suite("F3 #40 — undo/redo restores exact author attribution (host E2E, no LLM)", () => {
+  test("undo of a deletion of AGENT text restores its agent span (not neutral, not human)", async () => {
+    const { doc } = await freshDoc("docs/s40agent.md", "Human start. xxxx end.\n");
+    const api = await getApi();
+    const ctl = api.attributionController;
+
+    // Make "xxxx" agent-authored via the seam → an agent span over "ROBOT".
+    const t = "xxxx";
+    const start = doc.getText().indexOf(t);
+    const ok = await ctl.applyAgentEdit(
+      doc,
+      new vscode.Range(doc.positionAt(start), doc.positionAt(start + t.length)),
+      "ROBOT",
+      AGENT,
+      { turnId: "turn-s40" },
+    );
+    assert.strictEqual(ok, true, "seam edit applies");
+    await settle();
+    const key = api.proposalController.keyFor(doc);
+    assert.ok(
+      ctl.getSpans(key).some((s) => s.authorKind === "agent" && doc.getText().slice(s.range.start, s.range.end).includes("ROBOT")),
+      "ROBOT is agent-attributed after the seam edit",
+    );
+
+    // Human deletes "ROBOT" (buffer stays dirty: it already diverged from disk).
+    const rs = doc.getText().indexOf("ROBOT");
+    const del = new vscode.WorkspaceEdit();
+    del.delete(doc.uri, new vscode.Range(doc.positionAt(rs), doc.positionAt(rs + "ROBOT".length)));
+    assert.ok(await vscode.workspace.applyEdit(del), "delete applied");
+    await settle();
+    assert.ok(!doc.getText().includes("ROBOT"), "ROBOT deleted");
+
+    // Undo the deletion → ROBOT re-inserted. #40: its AGENT span is restored.
+    await vscode.window.showTextDocument(doc);
+    await vscode.commands.executeCommand("undo");
+    await settle();
+    assert.ok(doc.getText().includes("ROBOT"), "undo restored ROBOT");
+    assert.ok(doc.isDirty, "buffer still dirty → attribution branch ran");
+
+    const r2 = doc.getText().indexOf("ROBOT");
+    const spans = ctl.getSpans(key);
+    const over = spans.filter((s) => s.range.start < r2 + 5 && s.range.end > r2);
+    assert.ok(over.length > 0, "restored ROBOT carries a span");
+    assert.ok(over.every((s) => s.authorKind === "agent"), `restored ROBOT is agent-attributed, got ${JSON.stringify(over)}`);
+  });
+
+  test("edit → undo → redo round-trips attribution to identical state", async () => {
+    const { doc } = await freshDoc("docs/s40roundtrip.md", "Base alpha. yyyy omega.\n");
+    const api = await getApi();
+    const ctl = api.attributionController;
+    const key = api.proposalController.keyFor(doc);
+
+    const start = doc.getText().indexOf("yyyy");
+    await ctl.applyAgentEdit(
+      doc,
+      new vscode.Range(doc.positionAt(start), doc.positionAt(start + 4)),
+      "BLUEWORD",
+      AGENT,
+      { turnId: "turn-s40b" },
+    );
+    await settle();
+    const norm = (k: string) =>
+      ctl
+        .getSpans(k)
+        .map((s) => ({ a: s.authorKind, t: doc.getText().slice(s.range.start, s.range.end) }))
+        .sort((x, y) => (x.t < y.t ? -1 : 1));
+    const afterAgent = JSON.stringify(norm(key));
+    assert.ok(afterAgent.includes("BLUEWORD") && afterAgent.includes("agent"), "agent span present after the edit");
+
+    // Delete BLUEWORD, then undo (restore) then redo (re-delete) then undo again.
+    const bs = doc.getText().indexOf("BLUEWORD");
+    const del = new vscode.WorkspaceEdit();
+    del.delete(doc.uri, new vscode.Range(doc.positionAt(bs), doc.positionAt(bs + "BLUEWORD".length)));
+    await vscode.workspace.applyEdit(del);
+    await settle();
+    await vscode.window.showTextDocument(doc);
+    await vscode.commands.executeCommand("undo"); // restore BLUEWORD
+    await settle();
+    assert.ok(doc.getText().includes("BLUEWORD"), "undo restored BLUEWORD");
+    assert.strictEqual(JSON.stringify(norm(key)), afterAgent, "attribution after undo matches the pre-deletion state exactly");
+  });
+});

test/e2e/suite/undoCapable.ts

@@ -1,41 +0,0 @@
-import * as fs from "fs";
-import * as path from "path";
-import * as vscode from "vscode";
-
-/**
- * #54: `vscode.commands.executeCommand("undo")` is non-functional in some headless
- * `.vscode-test` instances (it does not restore the buffer), which false-fails
- * every undo-dependent E2E (#38, #40) and makes `main` E2E red there. This is a
- * RUNTIME probe: it performs a real edit-then-undo on a scratch buffer and reports
- * whether undo actually restored it. Undo-dependent suites gate on it — running
- * normally where undo works (real coverage), skipping with a loud warning where it
- * doesn't (no false red, no silent loss — the skip is logged). Memoized per run.
- */
-let cached: boolean | undefined;
-
-export async function undoWorks(): Promise<boolean> {
-  if (cached !== undefined) return cached;
-  const abs = path.join(process.env.E2E_WORKSPACE!, "docs/.undo-probe.md");
-  fs.mkdirSync(path.dirname(abs), { recursive: true });
-  fs.writeFileSync(abs, "undo probe baseline\n", "utf8");
-  const doc = await vscode.workspace.openTextDocument(vscode.Uri.file(abs));
-  await vscode.window.showTextDocument(doc);
-  await new Promise((r) => setTimeout(r, 250));
-  const edit = new vscode.WorkspaceEdit();
-  edit.insert(doc.uri, doc.positionAt(doc.getText().length), "PROBE-EDIT-MARKER");
-  await vscode.workspace.applyEdit(edit);
-  await new Promise((r) => setTimeout(r, 250));
-  if (!doc.getText().includes("PROBE-EDIT-MARKER")) {
-    cached = false; // even the edit didn't take — treat as not undo-capable
-    return cached;
-  }
-  await vscode.commands.executeCommand("undo");
-  await new Promise((r) => setTimeout(r, 250));
-  cached = !doc.getText().includes("PROBE-EDIT-MARKER"); // undo removed the marker → undo works
-  return cached;
-}
-
-/** Loud, single-line reason logged when an undo suite skips (no silent loss — #54). */
-export const UNDO_SKIP_REASON =
-  "[E2E] SKIPPING undo-dependent suite — executeCommand('undo') is non-functional in this " +
-  "VS Code test instance (see vscode-cowriting-plugin#54). These tests run where undo works.";

test/e2e/suite/undoMarks.test.ts

@@ -3,7 +3,6 @@ import * as fs from "fs";
 import * as path from "path";
 import * as vscode from "vscode";
 import type { CowritingApi } from "../../../src/extension";
-import { undoWorks, UNDO_SKIP_REASON } from "./undoCapable";
 
 const WS = process.env.E2E_WORKSPACE!;
 const settle = () => new Promise((r) => setTimeout(r, 400));
@@ -35,14 +34,6 @@ suite("F10 #38 — undo does not mis-attribute restored text (host E2E, no LLM)"
   const DOC_REL = "docs/undo38.md";
   const BASE = "Alpha bravo charlie.\n";
 
-  // #54: skip (loudly) where executeCommand("undo") is non-functional; run where it works.
-  suiteSetup(async function () {
-    if (!(await undoWorks())) {
-      console.warn(UNDO_SKIP_REASON);
-      this.skip();
-    }
-  });
-
   test("undo of a deletion of baseline text leaves it unattributed (not human)", async () => {
     const { doc, key } = await freshDoc(DOC_REL, BASE);
     const api = await getApi();