refactor: migrate test runner from vitest to bun:test

- Replace vitest with bun:test across all 8 packages (47 test files)
- vi.spyOn → spyOn, vi.restoreAllMocks() → mock.restore() (3 files)
- toHaveBeenCalledOnce → toHaveBeenCalledTimes(1) (bun:test compat)
- Delete all vitest.config.ts files
- Remove vitest from devDependencies
- Add preload.ts for process.exit mock (cli-workflow)
- Fix import ordering (biome check --write)

All tests pass. Closes #601

packages/workflow-util-agent/__tests__/adapter-retry.test.ts

@@ -1,5 +1,5 @@
+import { describe, expect, test } from "bun:test";
 import { createMemoryStore, putSchema } from "@ocas/core";
-import { describe, expect, test } from "vitest";
 
 import { tryFrontmatterFastPath } from "../src/frontmatter.js";
 

packages/workflow-util-agent/__tests__/adapter-stdout.test.ts

@@ -1,5 +1,5 @@
+import { describe, expect, test } from "bun:test";
 import { createMemoryStore, putSchema } from "@ocas/core";
-import { describe, expect, test } from "vitest";
 
 import { tryFrontmatterFastPath } from "../src/frontmatter.js";
 

packages/workflow-util-agent/__tests__/build-continuation-prompt.test.ts

@@ -1,5 +1,5 @@
+import { describe, expect, test } from "bun:test";
 import type { StepContext } from "@uncaged/workflow-protocol";
-import { describe, expect, test } from "vitest";
 import { buildContinuationPrompt } from "../src/build-continuation-prompt.js";
 
 const reviewerStep: StepContext = {

packages/workflow-util-agent/__tests__/build-output-format-instruction.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, test } from "vitest";
+import { describe, expect, test } from "bun:test";
 
 import { buildOutputFormatInstruction } from "../src/build-output-format-instruction.js";
 

packages/workflow-util-agent/__tests__/build-role-prompt.test.ts

@@ -1,5 +1,5 @@
+import { describe, expect, test } from "bun:test";
 import type { RoleDefinition } from "@uncaged/workflow-protocol";
-import { describe, expect, test } from "vitest";
 import { buildRolePrompt } from "../src/build-role-prompt.js";
 
 describe("buildRolePrompt", () => {

packages/workflow-util-agent/__tests__/context.test.ts

@@ -1,4 +1,4 @@
-import { describe, expect, test } from "vitest";
+import { describe, expect, test } from "bun:test";
 
 // We need to test buildHistory indirectly through buildContext
 // since buildHistory is not exported. For now, we'll test the integration

packages/workflow-util-agent/__tests__/frontmatter-fast-path.test.ts

@@ -1,5 +1,5 @@
+import { describe, expect, test } from "bun:test";
 import { createMemoryStore, putSchema } from "@ocas/core";
-import { describe, expect, test } from "vitest";
 
 import { tryFrontmatterFastPath } from "../src/frontmatter.js";
 

packages/workflow-util-agent/__tests__/session-cache.test.ts

@@ -1,7 +1,7 @@
+import { afterEach, beforeEach, describe, expect, test } from "bun:test";
 import { mkdir, readdir, readFile, rm, stat, writeFile } from "node:fs/promises";
 import { dirname, join } from "node:path";
 import type { ThreadId } from "@uncaged/workflow-protocol";
-import { afterEach, beforeEach, describe, expect, test } from "vitest";
 
 import { getCachedSessionId, getCachePath, setCachedSessionId } from "../src/session-cache.js";
 import { resolveStorageRoot } from "../src/storage.js";

packages/workflow-util-agent/package.json

@@ -16,8 +16,8 @@
   },
   "scripts": {
     "prepublishOnly": "echo 'Use bun run release from repo root' && exit 1",
-    "test": "vitest run",
-    "test:ci": "vitest run"
+    "test": "bun test __tests__/ src/__tests__/",
+    "test:ci": "bun test __tests__/ src/__tests__/"
   },
   "dependencies": {
     "@ocas/core": "^0.1.1",

packages/workflow-util-agent/src/__tests__/parseArgv.test.ts

@@ -1,4 +1,4 @@
-import { afterEach, beforeEach, describe, expect, test } from "vitest";
+import { afterEach, beforeEach, describe, expect, test } from "bun:test";
 
 describe("parseArgv empty prompt error message", () => {
   let stderrOutput: string;

packages/workflow-util-agent/vitest.config.ts

@@ -1,8 +0,0 @@
-import { defineConfig } from "vitest/config";
-
-export default defineConfig({
-  test: {
-    include: ["src/__tests__/**/*.test.ts"],
-    passWithNoTests: true,
-  },
-});