F4 SLICE-5: host E2E (propose/accept/reject/persist/stale/coexist) + seam fix: event-level net-effect matching survives host word-diff splitting (INV-9) (#12)

The accept E2E exposed a latent F3 limitation: VS Code word-diffs one
applied WorkspaceEdit into several minimal hunks when old/new share
interior tokens, so the registry's per-hunk exact match missed and seam
edits fell through as fragmented human spans. PendingEditRegistry.match
is replaced by matchEvent (all hunks inside the registered full range +
equal net delta — one applyEdit is one change event). Plan AMENDMENT 1.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test/e2e/fixtures/workspace/docs/proposal.md

@@ -0,0 +1,9 @@
+# Proposal fixture
+
+A stable opening paragraph.
+
+The propose target sentence lives here.
+
+A second target for coexistence checks.
+
+A stable closing paragraph.

test/e2e/suite-no-workspace/noWorkspace.test.ts

@@ -25,6 +25,9 @@ suite("no-workspace activation (#8)", () => {
       "cowriting.editSelection",
       "cowriting.toggleAttribution",
       "cowriting.applyAgentEdit",
+      "cowriting.acceptProposal",
+      "cowriting.rejectProposal",
+      "cowriting.proposeAgentEdit",
     ]) {
       assert.ok(all.includes(command), `${command} is registered`);
     }

test/e2e/suite/proposals.test.ts

@@ -0,0 +1,163 @@
+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";
+import type { Artifact } from "../../../src/model";
+
+const WS = process.env.E2E_WORKSPACE!;
+const DOC_REL = "docs/proposal.md";
+
+function sidecarPath(): string {
+  return path.join(WS, ".threads", "docs", "proposal.md.json");
+}
+function readSidecar(): Artifact {
+  return JSON.parse(fs.readFileSync(sidecarPath(), "utf8")) as Artifact;
+}
+async function openDoc(): Promise<vscode.TextDocument> {
+  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<CowritingApi> {
+  const ext = vscode.extensions.getExtension("benstull.vscode-cowriting-plugin")!;
+  const api = (await ext.activate()) as CowritingApi;
+  assert.ok(api?.proposalController, "extension exports proposalController");
+  return api;
+}
+async function proposeViaCommand(
+  doc: vscode.TextDocument,
+  target: string,
+  newText: string,
+  turnId: string,
+): Promise<string> {
+  const start = doc.getText().indexOf(target);
+  assert.ok(start >= 0, `fixture contains "${target}"`);
+  const id = await vscode.commands.executeCommand<string>("cowriting.proposeAgentEdit", {
+    uri: doc.uri.toString(),
+    start,
+    end: start + target.length,
+    newText,
+    model: "sonnet",
+    sessionId: "e2e-prop",
+    turnId,
+    instruction: "e2e instruction",
+  });
+  assert.ok(id, "propose returns the proposal id");
+  return id!;
+}
+async function externalWriteAndReload(uri: vscode.Uri, content: string): Promise<vscode.TextDocument> {
+  fs.writeFileSync(uri.fsPath, content, "utf8");
+  const doc = await vscode.workspace.openTextDocument(uri);
+  await vscode.window.showTextDocument(doc);
+  await vscode.commands.executeCommand("workbench.action.files.revert");
+  return doc;
+}
+const settle = () => new Promise((r) => setTimeout(r, 300));
+
+// Tests are ORDER-DEPENDENT (F2/F3 pattern): later tests consume earlier state.
+// This suite OWNS docs/proposal.md; threads owns docs/sample.md, attribution
+// owns docs/attrib.md — fixtures stay disjoint.
+suite("F4 propose/accept (host E2E — programmatic ingress, no LLM)", () => {
+  const TARGET = "The propose target sentence lives here.";
+  const REPLACEMENT = "PROPOSED-BY-CLAUDE replacement sentence.";
+
+  test("propose records + renders a pending proposal and does NOT touch the document (INV-10)", async () => {
+    const doc = await openDoc();
+    const api = await getApi();
+    const before = doc.getText();
+    await proposeViaCommand(doc, TARGET, REPLACEMENT, "turn-p1");
+    await settle();
+    assert.strictEqual(doc.getText(), before, "document text unchanged (INV-10)");
+    const rendered = api.proposalController.getRendered(DOC_REL);
+    assert.strictEqual(rendered.length, 1);
+    assert.strictEqual(rendered[0].pending, true);
+    assert.strictEqual(rendered[0].turnId, "turn-p1");
+    const art = readSidecar();
+    assert.strictEqual(art.proposals.length, 1, "proposal persisted at propose time");
+    assert.strictEqual(art.anchors[art.proposals[0].anchorId].fingerprint.text, TARGET);
+  });
+
+  test("accept applies via the seam: text replaced, Claude-attributed, proposal removed (INV-9/11/13)", async () => {
+    const doc = await openDoc();
+    const api = await getApi();
+    const id = api.proposalController.getRendered(DOC_REL)[0].id;
+    const ok = await api.proposalController.acceptById(DOC_REL, id);
+    assert.strictEqual(ok, true, "accept applies");
+    await settle();
+    assert.ok(doc.getText().includes(REPLACEMENT), "replacement landed");
+    assert.ok(!doc.getText().includes(TARGET), "target gone");
+    const spans = api.attributionController.getSpans(DOC_REL);
+    const agent = spans.find((s) => s.turnId === "turn-p1");
+    assert.ok(agent, `accepted text is Claude-attributed with the proposal's turnId — got spans: ${JSON.stringify(spans)}`);
+    assert.strictEqual(agent!.authorKind, "agent");
+    assert.strictEqual(api.proposalController.getRendered(DOC_REL).length, 0, "proposal gone (INV-13)");
+    assert.strictEqual(readSidecar().proposals.length, 0, "removed from the sidecar");
+  });
+
+  test("reject leaves the document untouched and removes the proposal (PUC-3)", async () => {
+    const doc = await openDoc();
+    const api = await getApi();
+    const before = doc.getText();
+    const id = await proposeViaCommand(doc, "A second target for coexistence checks.", "WOULD-BE replacement.", "turn-p2");
+    await settle();
+    assert.strictEqual(api.proposalController.rejectById(DOC_REL, id), true);
+    await settle();
+    assert.strictEqual(doc.getText(), before, "document untouched");
+    assert.strictEqual(api.proposalController.getRendered(DOC_REL).length, 0);
+    assert.strictEqual(readSidecar().proposals.length, 0);
+  });
+
+  test("a pending proposal persists, survives reload, and re-anchors after an external move (PUC-4)", async () => {
+    let doc = await openDoc();
+    const api = await getApi();
+    const anchor = "A stable closing paragraph.";
+    await proposeViaCommand(doc, anchor, "A PROPOSED closing paragraph.", "turn-p3");
+    await settle();
+    const uri = vscode.Uri.file(path.join(WS, DOC_REL));
+    doc = await externalWriteAndReload(uri, "PREPENDED LINE\n\n" + doc.getText());
+    await settle();
+    api.proposalController.renderAll(doc);
+    const rendered = api.proposalController.getRendered(DOC_REL);
+    assert.strictEqual(rendered.length, 1, "proposal survived reload");
+    assert.strictEqual(rendered[0].pending, true, "still decidable");
+    const moved = doc.getText().indexOf(anchor);
+    assert.strictEqual(rendered[0].range.start, moved, "re-anchored after the move");
+  });
+
+  test("editing the target text makes the proposal stale: flagged, accept refused, doc untouched (INV-11)", async () => {
+    let doc = await openDoc();
+    const api = await getApi();
+    const id = api.proposalController.getRendered(DOC_REL)[0].id;
+    const mangled = doc.getText().replace("A stable closing paragraph.", "A reworded closing paragraph.");
+    doc = await externalWriteAndReload(vscode.Uri.file(path.join(WS, DOC_REL)), mangled);
+    await settle();
+    api.proposalController.renderAll(doc);
+    assert.strictEqual(api.proposalController.getStaleCount(DOC_REL), 1, "flagged stale");
+    const before = doc.getText();
+    const ok = await api.proposalController.acceptById(DOC_REL, id);
+    assert.strictEqual(ok, false, "accept refused (INV-11)");
+    assert.strictEqual(doc.getText(), before, "document untouched");
+    assert.strictEqual(readSidecar().proposals.length, 1, "proposal still pending (recoverable)");
+    // discard the husk so later tests see a clean sidecar
+    assert.strictEqual(api.proposalController.rejectById(DOC_REL, id), true);
+  });
+
+  test("multiple pending proposals coexist and are decidable out of order (PUC-5)", async () => {
+    const doc = await openDoc();
+    const api = await getApi();
+    const id1 = await proposeViaCommand(doc, "A stable opening paragraph.", "An ACCEPTED opening paragraph.", "turn-p4");
+    const id2 = await proposeViaCommand(doc, "PROPOSED-BY-CLAUDE replacement sentence.", "A REPLACED-AGAIN sentence.", "turn-p5");
+    await settle();
+    assert.strictEqual(api.proposalController.getRendered(DOC_REL).length, 2);
+    // decide the SECOND first, then the first — order independence
+    assert.strictEqual(await api.proposalController.acceptById(DOC_REL, id2), true);
+    await settle();
+    assert.strictEqual(await api.proposalController.acceptById(DOC_REL, id1), true);
+    await settle();
+    assert.ok(doc.getText().includes("An ACCEPTED opening paragraph."));
+    assert.ok(doc.getText().includes("A REPLACED-AGAIN sentence."));
+    assert.strictEqual(api.proposalController.getRendered(DOC_REL).length, 0);
+  });
+});

test/pendingEdits.test.ts

@@ -8,26 +8,53 @@ const AGENT: Provenance = {
 };
 
 describe("PendingEditRegistry (INV-9)", () => {
-  it("matches and consumes an exact registration", () => {
+  it("matches and consumes a single-hunk event equal to the registration", () => {
     const reg = new PendingEditRegistry();
-    reg.register({ docPath: "d.md", start: 3, end: 7, newText: "new", provenance: AGENT, turnId: "t1" });
-    const hit = reg.match("d.md", { start: 3, end: 7, text: "new" });
+    reg.register({
+      docPath: "d.md", start: 3, end: 7, newText: "new", provenance: AGENT, turnId: "t1",
+      full: { start: 3, end: 7, newLength: 3 },
+    });
+    const hit = reg.matchEvent("d.md", [{ start: 3, end: 7, newLength: 3 }]);
     expect(hit?.turnId).toBe("t1");
-    expect(reg.match("d.md", { start: 3, end: 7, text: "new" })).toBeNull();
+    expect(reg.matchEvent("d.md", [{ start: 3, end: 7, newLength: 3 }])).toBeNull();
   });
-  it("does not match a different doc, range, or text (human typing stays human)", () => {
+  it("matches a HOST-SPLIT event: several hunks inside the full range with the same net delta", () => {
+    // The host word-diffs one applied replace into multiple minimal hunks
+    // (observed on F4 accept) — per-hunk equality misses; net-effect matches.
+    const reg = new PendingEditRegistry();
+    reg.register({
+      docPath: "d.md", start: 10, end: 50, newText: "x".repeat(45), provenance: AGENT, turnId: "t2",
+      full: { start: 10, end: 50, newLength: 45 },
+    });
+    const hit = reg.matchEvent("d.md", [
+      { start: 12, end: 20, newLength: 9 },
+      { start: 25, end: 30, newLength: 6 },
+      { start: 40, end: 48, newLength: 11 },
+    ]);
+    expect(hit?.turnId).toBe("t2");
+  });
+  it("does not match a different doc, hunks outside the full range, or a different delta", () => {
+    const reg = new PendingEditRegistry();
+    reg.register({
+      docPath: "d.md", start: 3, end: 7, newText: "new", provenance: AGENT,
+      full: { start: 3, end: 7, newLength: 3 },
+    });
+    expect(reg.matchEvent("other.md", [{ start: 3, end: 7, newLength: 3 }])).toBeNull();
+    expect(reg.matchEvent("d.md", [{ start: 3, end: 8, newLength: 4 }])).toBeNull();
+    expect(reg.matchEvent("d.md", [{ start: 3, end: 7, newLength: 4 }])).toBeNull();
+    expect(reg.matchEvent("d.md", [])).toBeNull();
+  });
+  it("falls back to the minimized range when no full extent was registered", () => {
     const reg = new PendingEditRegistry();
     reg.register({ docPath: "d.md", start: 3, end: 7, newText: "new", provenance: AGENT });
-    expect(reg.match("other.md", { start: 3, end: 7, text: "new" })).toBeNull();
-    expect(reg.match("d.md", { start: 3, end: 8, text: "new" })).toBeNull();
-    expect(reg.match("d.md", { start: 3, end: 7, text: "neww" })).toBeNull();
+    expect(reg.matchEvent("d.md", [{ start: 3, end: 7, newLength: 3 }])).not.toBeNull();
   });
   it("unregister removes a failed application", () => {
     const reg = new PendingEditRegistry();
     const p = { docPath: "d.md", start: 0, end: 0, newText: "x", provenance: AGENT };
     reg.register(p);
     reg.unregister(p);
-    expect(reg.match("d.md", { start: 0, end: 0, text: "x" })).toBeNull();
+    expect(reg.matchEvent("d.md", [{ start: 0, end: 0, newLength: 1 }])).toBeNull();
   });
   it("unregister reports whether the registration was still pending", () => {
     const reg = new PendingEditRegistry();
@@ -35,7 +62,7 @@ describe("PendingEditRegistry (INV-9)", () => {
     reg.register(p);
     expect(reg.unregister(p)).toBe(true);
     reg.register(p);
-    reg.match("d.md", { start: 0, end: 0, text: "x" });
+    reg.matchEvent("d.md", [{ start: 0, end: 0, newLength: 1 }]);
     expect(reg.unregister(p)).toBe(false);
   });
 });