test(FN-4946): add implicit completion refusal guard coverage

Fusion-Task-Id: FN-4946
Fusion-Task-Lineage: 9a48f72f-d2cc-4950-8a00-f69053dd1163

packages/engine/src/__tests__/executor-task-done-shared-helper.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, it } from "vitest";
+import { readFileSync } from "node:fs";
+import { evaluateTaskDoneRefusal } from "../executor.js";
+
+describe("FN-4946 shared task_done refusal helper invariant", () => {
+  it("keeps a single helper implementation and routes explicit+implicit paths through it", () => {
+    const source = readFileSync(new URL("../executor.ts", import.meta.url), "utf8");
+    const invocations = source.match(/evaluateTaskDoneRefusal\(/g) ?? [];
+    const helperDecl = source.match(/\bfunction evaluateTaskDoneRefusal\b/g) ?? [];
+    const dissentDecl = source.match(/\bconst DISSENT_PATTERNS\b/g) ?? [];
+
+    expect(invocations.length).toBeGreaterThanOrEqual(3);
+    expect(helperDecl).toHaveLength(1);
+    expect(dissentDecl).toHaveLength(1);
+  });
+
+  it("returns pending-code-review-revise for a pending step with REVISE and no summary", () => {
+    const result = evaluateTaskDoneRefusal(
+      {
+        id: "FN-4946-H",
+        title: "t",
+        description: "",
+        column: "in-progress",
+        dependencies: [],
+        steps: [{ name: "Step 1", status: "in-progress" }],
+        currentStep: 0,
+        createdAt: new Date().toISOString(),
+        updatedAt: new Date().toISOString(),
+      } as any,
+      {},
+      new Map([[0, "REVISE"]]),
+    );
+
+    expect(result.ok).toBe(false);
+    if (result.ok) throw new Error("expected refusal");
+    expect(result.refusalClass).toBe("pending-code-review-revise");
+  });
+});