feat(FN-4839): harden real-git test timeouts across engine suites

Hardens test timeouts across 12 reliability and integration test files (branch-conflict recovery, merger diff/overlap guards, self-healing, worktree hydration, workflow/file-scope interactions), covering both real-git and mock-based test lanes with consistent timeout adjustments to reduce flakiness.

Fusion-Task-Id: FN-4839

packages/engine/src/__tests__/reliability-interactions/audit-and-recovery.test.ts

@@ -1,3 +1,5 @@
+// Real-git wallclock under parallel CI load; do not lower per-test timeouts
+// without re-measuring under pnpm test:full. (FN-4839)
 import { afterEach, describe, expect, it } from "vitest";
 import { makeReliabilityFixture, hasGit, git } from "./_helpers.js";
 
@@ -23,7 +25,7 @@ describeIfGit("reliability interactions: audit + recovery", () => {
     const task = await fx.store.getTask(fx.task.id);
     expect(recovered).toBeGreaterThanOrEqual(0);
     expect(["in-review", "done"]).toContain(task?.column ?? "");
-  });
+  }, 20_000);
 
   it("Case 4: already-done is idempotent", async () => {
     const fx = await makeReliabilityFixture({ taskId: "FN-4361-C4" });
@@ -31,7 +33,7 @@ describeIfGit("reliability interactions: audit + recovery", () => {
     await fx.store.updateTask(fx.task.id, { column: "done", status: null } as any);
     const recovered = await fx.selfHeal.recoverAlreadyMergedReviewTasks();
     expect(recovered).toBe(0);
-  });
+  }, 20_000);
 
   it("Case 13: tree-equal does not promote when worktree has staged changes", async () => {
     const fx = await makeReliabilityFixture({ taskId: "FN-4361-C13" });
@@ -51,5 +53,5 @@ describeIfGit("reliability interactions: audit + recovery", () => {
     const task = await fx.store.getTask(fx.task.id);
     expect(["in-review", "done"]).toContain(task?.column ?? "");
     expect(git(fx.rootDir, "git rev-parse HEAD").length).toBe(40);
-  });
+  }, 20_000);
 });

packages/engine/src/__tests__/reliability-interactions/integrity-warning-persisted-dedup.test.ts

@@ -1,4 +1,7 @@
 /**
+ * Real-git wallclock under parallel CI load; do not lower per-test timeouts
+ * without re-measuring under pnpm test:full. (FN-4839)
+ *
  * FN-4811 follow-up: persisted dedup of done-task finalize-integrity warnings.
  *
  * Before this change, `SelfHealingManager.reconcileDoneTaskIntegrity()` deduped

packages/engine/src/__tests__/reliability-interactions/merge-strategy-and-overlap.test.ts

@@ -1,3 +1,5 @@
+// Real-git wallclock under parallel CI load; do not lower per-test timeouts
+// without re-measuring under pnpm test:full. (FN-4839)
 import { afterEach, describe, expect, it } from "vitest";
 import { checkDiffVolume } from "../../merger-diff-volume-gate.js";
 import { makeReliabilityFixture, hasGit, git } from "./_helpers.js";

packages/engine/src/__tests__/reliability-interactions/no-changes-finalized.real-git.test.ts

@@ -1,3 +1,5 @@
+// Real-git wallclock under parallel CI load; do not lower per-test timeouts
+// without re-measuring under pnpm test:full. (FN-4839)
 import { describe, it, expect, vi } from "vitest";
 import { classifyOwnedLandedEvidence } from "../../merger.js";
 import { makeReliabilityFixture, hasGit } from "./_helpers.js";
@@ -75,5 +77,5 @@ describe("no-changes-finalized reliability interactions (real git)", () => {
     } finally {
       await fixture.cleanup();
     }
-  });
+  }, 20_000);
 });

packages/engine/src/__tests__/reliability-interactions/workflow-and-file-scope.test.ts

@@ -1,3 +1,5 @@
+// Real-git wallclock under parallel CI load; do not lower per-test timeouts
+// without re-measuring under pnpm test:full. (FN-4839)
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { assertSquashOverlapsFileScope, FileScopeViolationError } from "../../merger.js";
 import { makeReliabilityFixture, hasGit, git } from "./_helpers.js";