F3 hardening: observable seam misses, cheaper disk-compare, E2E ordering notes (#6)

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

test/e2e/suite/attribution.test.ts

@@ -35,6 +35,9 @@ async function externalWriteAndReload(uri: vscode.Uri, content: string): Promise
 }
 const settle = () => new Promise((r) => setTimeout(r, 300));
 
+// Tests are ORDER-DEPENDENT: later tests consume earlier tests' document/sidecar
+// state by design, mirroring the F2 suite. This suite owns docs/attrib.md;
+// the threads suite owns docs/sample.md — keep fixtures disjoint.
 suite("F3 live attribution (host E2E — seam-driven, no LLM)", () => {
   const TYPED = "A human-typed sentence. ";
 

test/pendingEdits.test.ts

@@ -29,6 +29,15 @@ describe("PendingEditRegistry (INV-9)", () => {
     reg.unregister(p);
     expect(reg.match("d.md", { start: 0, end: 0, text: "x" })).toBeNull();
   });
+  it("unregister reports whether the registration was still pending", () => {
+    const reg = new PendingEditRegistry();
+    const p = { docPath: "d.md", start: 0, end: 0, newText: "x", provenance: AGENT };
+    reg.register(p);
+    expect(reg.unregister(p)).toBe(true);
+    reg.register(p);
+    reg.match("d.md", { start: 0, end: 0, text: "x" });
+    expect(reg.unregister(p)).toBe(false);
+  });
 });
 
 describe("minimizeReplace (host diff-minimization mirror)", () => {