fix(docsync): admit the Write tool's temp sibling of the receipt record (0230fc2 rerun: both lifecycle cases red on it)

The paid rerun at 0230fc2 cleared every earlier refusal and both cases then
failed on one path: forbidden docs write: .gstack/tmp/docs-audit.json.tmp.<pid>.<12 hex>.
Claude Code's Write and Edit tools land every file, new ones included, through
that sibling plus fsync and rename, and the fixture's kernel observer proved
such a landing for the document only (atomicTargets: [DOC_PATH]).

The observer now treats the record's sibling as a transient file too, and
docsWriteFailures admits it only as the cookie-paired MOVED_FROM source of a
MOVED_TO on the record whose other events are create/modify/attrib/close_write
and which is left in neither snapshot nor in changed. A lingering sibling, an
unpaired move, a move onto another path or a sibling of the document moved onto
the record stay forbidden (grammar test). A live check on this machine saw the
second landing's create/modify/close_write/moved_from events admitted and a
stray sibling refused.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

test/docsync-command-grammar.test.ts

@@ -540,6 +540,20 @@ test('Step 14.5 housekeeping commands and the docs record are declared exactly a
   expect(docsWriteFailures(observed(['.qa-state/.observer-check', ...DOCS_AUDIT_RECORD_PATHS]), [])).toEqual([]);
   expect(docsWriteFailures(observed(['.git/info/attributes']), [])).toEqual(['forbidden docs write: .git/info/attributes']);
   expect(docsWriteFailures(observed(['.gstack/tmp/review-loop.json']), [DOC_PATH])).toEqual(['forbidden docs write: .gstack/tmp/review-loop.json']);
+  // The Write tool lands the record through `<record>.tmp.<pid>.<12 hex>` + rename (gate: both lifecycle cases red at 0230fc2 on exactly
+  // that sibling). The sibling is admitted only as the cookie-paired source of a move onto the record that leaves nothing behind.
+  const temp = `${DOCS_AUDIT_RECORD}.tmp.564.6161e6c7f0b7`;
+  const moved = (edits: { path: string; mask: number; cookie?: number }[], after: Record<string, string> = {}) => ({
+    complete: true, failures: [], events: edits.map((e, at) => ({ path: e.path, mask: e.mask, cookie: e.cookie ?? 0, at })), changed: Object.keys(after), before: {}, after, limits: [],
+  });
+  const landing = [{ path: temp, mask: 0x100 }, { path: temp, mask: 0x2 }, { path: temp, mask: 0x8 }, { path: temp, mask: 0x40, cookie: 7 }, { path: DOCS_AUDIT_RECORD, mask: 0x80, cookie: 7 }];
+  expect(docsWriteFailures(moved(landing), [])).toEqual([]);
+  expect(docsWriteFailures(moved(landing.slice(1)), [])).toEqual([]);
+  expect(docsWriteFailures(moved(landing, { [temp]: '0:' + 'a'.repeat(64) }), [])).toEqual([`forbidden docs write: ${temp}`]);
+  expect(docsWriteFailures(moved(landing.slice(0, 3)), [])).toEqual([`forbidden docs write: ${temp}`]);
+  expect(docsWriteFailures(moved([...landing.slice(0, 4), { path: '.gstack/tmp/other.json', mask: 0x80, cookie: 7 }]), [])).toEqual([`forbidden docs write: ${temp}`, 'forbidden docs write: .gstack/tmp/other.json']);
+  expect(docsWriteFailures(moved([...landing.slice(0, 3), { path: temp, mask: 0x40, cookie: 7 }, { path: DOCS_AUDIT_RECORD, mask: 0x80, cookie: 7 }, { path: temp, mask: 0x100 }]), [])).toEqual([`forbidden docs write: ${temp}`]);
+  expect(docsWriteFailures(moved([{ path: `${DOC_PATH}.tmp.564.6161e6c7f0b7`, mask: 0x40, cookie: 9 }, { path: DOCS_AUDIT_RECORD, mask: 0x80, cookie: 9 }]), [])).toEqual([`forbidden docs write: ${DOC_PATH}.tmp.564.6161e6c7f0b7`]);
   expect(docsToolFailures(write(path.join(fixture.repo, '.gstack/tmp/review-loop.json')), fixture, [], false)).toEqual(['non-document product write attempt', 'write outside docs fixture authority']);
   expect(docsToolFailures(write(path.join(fixture.repo, '.gstack/ship-policy.json')), fixture, [], false)).toEqual(['non-document product write attempt', 'write outside docs fixture authority']);
   expect(gitAt(fixture.repo, 'rev-parse', '--verify', 'origin/main')).toBe(gitAt(fixture.repo, 'rev-parse', '--verify', 'main'));

test/helpers/docsync-observer.ts

@@ -12,7 +12,26 @@ import { readOnlyCommandAllowed } from './read-only-commands';
 export { docsNativeInterface };
 
 export async function observeDocsWrites(fixture: ReturnType<typeof fixtureDocs>) {
-  return observeQAWrites(fixture.repo, { atomicTargets: [DOC_PATH] });
+  return observeQAWrites(fixture.repo, { atomicTargets: [DOC_PATH, DOCS_AUDIT_RECORD] });
+}
+
+/** Temp files the Write/Edit tool renamed onto the receipt record (`<record>.tmp.<pid>.<12 hex>`): created, written and closed
+ *  under the record's directory, then moved onto the record by a cookie-paired MOVED_FROM/MOVED_TO, and not left behind. */
+function docsRecordSources(observation: QAWriteObservation): Set<string> {
+  const sources = new Set<string>();
+  const events = observation.events;
+  for (const [index, event] of events.entries()) {
+    if (event.path !== DOCS_AUDIT_RECORD || event.mask !== 0x80 || !Number.isInteger(event.cookie) || event.cookie <= 0) continue;
+    const pair = events.flatMap((candidate, at) => candidate.cookie === event.cookie ? [at] : []);
+    if (pair.length !== 2 || pair[1] !== index) continue;
+    const source = events[pair[0]];
+    if (source.mask !== 0x40 || !source.path.startsWith(DOCS_AUDIT_RECORD + '.tmp.') || !/^\.tmp\.[1-9]\d*\.[0-9a-f]{12}$/.test(source.path.slice(DOCS_AUDIT_RECORD.length))
+      || Object.hasOwn(observation.before, source.path) || Object.hasOwn(observation.after, source.path) || observation.changed.includes(source.path)) continue;
+    const lifecycle = events.filter(candidate => candidate.path === source.path);
+    if (lifecycle.at(-1) !== source || lifecycle.some(candidate => candidate !== source && (candidate.cookie !== 0 || ![0x100, 0x2, 0x4, 0x8].includes(candidate.mask)))) continue;
+    sources.add(source.path);
+  }
+  return sources;
 }
 
 type DocsWriteContext = {
@@ -136,8 +155,9 @@ export function docsWriteFailures(observation: QAWriteObservation, allowed: stri
   const failures = [...observation.failures];
   if (!observation.complete) failures.push('incomplete docs write observation');
   const atomicSources = docsAtomicSources(observation, allowed, context);
+  const recordSources = docsRecordSources(observation);
   for (const file of new Set([...observation.events.map(e => e.path), ...observation.changed])) {
-    if (file !== '.qa-state/.observer-check' && !allowed.includes(file) && !DOCS_AUDIT_RECORD_PATHS.includes(file) && !atomicSources.has(file))
+    if (file !== '.qa-state/.observer-check' && !allowed.includes(file) && !DOCS_AUDIT_RECORD_PATHS.includes(file) && !atomicSources.has(file) && !recordSources.has(file))
       failures.push(`forbidden docs write: ${file}${atomicSources.deniedAt && path.dirname(file) === path.dirname(DOC_PATH) ? ` (atomic replacement unproven at ${atomicSources.deniedAt})` : ''}`);
     if (allowed.includes(file) && observation.before[file] && observation.after[file] &&
         observation.before[file].split(':')[0] !== observation.after[file].split(':')[0]) failures.push(`document mode changed: ${file}`);