feat(FN-4534): add auto-recovery dispatcher and pause-site wiring

Fusion-Task-Id: FN-4534
Fusion-Task-Lineage: 2b46a5df-efc6-4305-a0f2-69991e58512c

packages/engine/src/__tests__/reliability-interactions/auto-recovery-dispatch.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, it, vi } from "vitest";
+import type { Task } from "@fusion/core";
+import { AutoRecoveryDispatcher } from "../../auto-recovery.js";
+
+const baseTask = { id: "FN-1", recoveryRetryCount: 0 } as Task;
+
+describe("reliability interaction: auto-recovery dispatcher precedence", () => {
+  it("mode off preserves legacy pausedReason contract across wired classes", () => {
+    const dispatcher = new AutoRecoveryDispatcher({
+      taskStore: {} as never,
+      auditEmitter: { database: vi.fn(async () => {}), git: vi.fn(), filesystem: vi.fn() },
+    });
+
+    const wired = [
+      "branch-cross-contamination",
+      "branch-conflict-tripwire",
+      "branch-conflict-recovery-exhausted",
+      "branch-conflict-unrecoverable",
+    ] as const;
+
+    for (const klass of wired) {
+      const decision = dispatcher.classify({ class: klass, taskId: "FN-1", pausedReason: klass }, {
+        task: baseTask,
+        retryCount: 0,
+        settings: { mode: "off", maxRetries: 3 },
+      });
+      expect(decision.action).toBe("pause");
+      expect(decision.legacyPausedReason).toBe(klass);
+    }
+  });
+
+  it("deterministic recovery success can bypass dispatcher invocation", async () => {
+    const classify = vi.fn();
+    const deterministicFastPath = vi.fn(async () => true);
+
+    if (!(await deterministicFastPath())) {
+      classify();
+    }
+
+    expect(deterministicFastPath).toHaveBeenCalledOnce();
+    expect(classify).not.toHaveBeenCalled();
+  });
+});