test(FN-4398): complete Step 4 — add retry storm integration coverage

Fusion-Task-Id: FN-4398
Fusion-Task-Lineage: 8b898b2e-3468-4fa7-8546-b8f6ba52cf46

packages/engine/src/__tests__/executor-retry-storm.test.ts

@@ -0,0 +1,80 @@
+import { describe, expect, it, vi } from "vitest";
+
+import {
+  RetryStormError,
+  serializeRetryStormError,
+  type TaskDetail,
+} from "@fusion/core";
+import { recordRetry } from "../retry-burned-logger.js";
+
+function makeTask(overrides: Partial<TaskDetail> = {}): TaskDetail {
+  return {
+    id: "FN-4398",
+    lineageId: "lineage-1",
+    description: "retry storm",
+    column: "in-review",
+    status: "failed",
+    dependencies: [],
+    steps: [],
+    currentStep: 0,
+    log: [],
+    prompt: "prompt",
+    createdAt: "2026-01-01T00:00:00.000Z",
+    updatedAt: "2026-01-01T00:00:00.000Z",
+    ...overrides,
+  };
+}
+
+describe("executor retry storm integration", () => {
+  it("throws and serializes RetryStormError on 26th retry and stays terminal", async () => {
+    const task = makeTask({
+      stuckKillCount: 5,
+      recoveryRetryCount: 5,
+      taskDoneRetryCount: 5,
+      workflowStepRetries: 5,
+      verificationFailureCount: 5,
+      reviewerContextRetryCount: 0,
+    });
+
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => undefined);
+    const store = {
+      updateTask: vi.fn(async (_id: string, patch: Record<string, unknown>) => {
+        Object.assign(task, patch);
+      }),
+      getTask: vi.fn(async () => task),
+      moveTask: vi.fn(async () => undefined),
+    };
+
+    let thrown: RetryStormError | undefined;
+    try {
+      await recordRetry({
+        store: store as never,
+        settings: {
+          maxReviewerContextRetries: 2,
+          maxTotalRetriesBeforeFail: 25,
+        },
+        task,
+        category: "reviewerContext",
+        role: "reviewer",
+        attempt: 1,
+      });
+    } catch (error) {
+      thrown = error as RetryStormError;
+      const serialized = serializeRetryStormError(thrown);
+      await store.updateTask(task.id, { error: JSON.stringify(serialized), status: "failed" });
+    }
+
+    expect(thrown).toBeInstanceOf(RetryStormError);
+    expect(task.error).toContain('"type":"RetryStormError"');
+    expect(task.error).toContain('"category":"reviewerContext"');
+    expect(task.error).toContain('"total":26');
+    expect(consoleSpy).toHaveBeenCalledWith(
+      expect.stringContaining("[retry-burned] retry-burned"),
+      expect.objectContaining({ taskId: task.id, category: "reviewerContext", total: expect.any(Number) }),
+    );
+    expect(task.column).toBe("in-review");
+    expect(store.moveTask).not.toHaveBeenCalled();
+
+    consoleSpy.mockRestore();
+  });
+});