test(git-sync): add reviewer-requested coverage across engine, server, client

Implements the test cases called out in the PR #119 review threads
(code-review, test-strategy report, red-team) — TESTS ONLY, no production
code changes.

packages/git-sync (vitest):
- lib converter/markdown gaps: pageBreak data-loss (it.fails repro),
  subpages lossy round-trip, nested/fenced callouts, ol->taskList bridge,
  column.width number<->string drift, empty details.
- engine units: parentFolderFile, planReconciliation swap/chained move,
  buildVaultLayout last-resort-by-id, firstDivergence, applyPushActions /
  applyPullActions failure isolation.
- real temp-git integration: diffNameStatus -z rename+add/modify
  alignment, copy-line behavior, per-invocation committer identity (no
  leak into repo/global config).
- ENFORCED type-level GitSyncClient contract via vitest typecheck over a
  *.test-d.ts file (tsconfig.vitest.json; build tsconfig untouched).

apps/server (jest):
- orchestrator: delete-cap neutralization + fail-safe, Redis lock / mutex
  skip ladder + release-on-throw, merge guard, pull/push order, remote
  template substitution, poll lifecycle.
- page-change listener: loop-guard, debounce coalescing, id resolution,
  error swallowing.
- vault registry, controller authz (trigger + status), env
  validation/getters, page.service git-sync provenance stamping,
  persistence precedence (agent > git-sync > user) + no boundary snapshot,
  space.service audit-delta, space.repo jsonb-merge, converter-gate corpus
  extension (mention/math/details/marks).

apps/client (vitest + testing-library):
- history-item git-sync badge: render gating + non-clickable.
- edit-space-form toggle: initial state, optimistic payload, rollback on
  error, disabled states.

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

apps/server/src/core/space/services/space.service.spec.ts

@@ -92,5 +92,64 @@ describe('SpaceService', () => {
 
       expect(spaceRepo.updateGitSyncSettings).not.toHaveBeenCalled();
     });
+
+    // --- audit delta on the git-sync toggle (test-strategy Module 4 / item #5)
+    // updateSpace builds a before/after delta only when a flag's value actually
+    // changes, and only logs an audit event when that delta is non-empty. These
+    // assert that contract specifically for gitSyncEnabled.
+    it('writes a SPACE_UPDATED audit delta on a REAL gitSyncEnabled change (false -> true)', async () => {
+      // Prior persisted state: gitSync.enabled = false; the request flips it on.
+      const { svc, auditService } = buildService({ gitSync: { enabled: false } });
+
+      await svc.updateSpace(
+        { spaceId, gitSyncEnabled: true } as any,
+        workspaceId,
+      );
+
+      expect(auditService.log).toHaveBeenCalledTimes(1);
+      expect(auditService.log).toHaveBeenCalledWith(
+        expect.objectContaining({
+          resourceId: spaceId,
+          spaceId,
+          changes: {
+            before: expect.objectContaining({ gitSyncEnabled: false }),
+            after: expect.objectContaining({ gitSyncEnabled: true }),
+          },
+        }),
+      );
+    });
+
+    it('also records the delta when no prior gitSync settings exist (undefined -> true defaults prev to false)', async () => {
+      // No gitSync key at all: prev resolves to the `?? false` default, so
+      // enabling it is still a real change and is audited.
+      const { svc, auditService } = buildService({});
+
+      await svc.updateSpace(
+        { spaceId, gitSyncEnabled: true } as any,
+        workspaceId,
+      );
+
+      expect(auditService.log).toHaveBeenCalledTimes(1);
+      const call = auditService.log.mock.calls[0][0];
+      expect(call.changes.before.gitSyncEnabled).toBe(false);
+      expect(call.changes.after.gitSyncEnabled).toBe(true);
+    });
+
+    it('does NOT write an audit delta on a no-op gitSyncEnabled (same value true -> true)', async () => {
+      // Prior persisted state already true; the request sets the same value.
+      // updateGitSyncSettings still runs (idempotent persist), but nothing is
+      // added to the before/after delta, so no audit event is emitted.
+      const { svc, spaceRepo, auditService } = buildService({
+        gitSync: { enabled: true },
+      });
+
+      await svc.updateSpace(
+        { spaceId, gitSyncEnabled: true } as any,
+        workspaceId,
+      );
+
+      expect(spaceRepo.updateGitSyncSettings).toHaveBeenCalledTimes(1);
+      expect(auditService.log).not.toHaveBeenCalled();
+    });
   });
 });