diff --git a/tests/agent/e2e-build.test.ts b/tests/agent/e2e-build.test.ts
new file mode 100644
index 0000000..c515a4e
--- /dev/null
+++ b/tests/agent/e2e-build.test.ts
@@ -0,0 +1,96 @@
+import { describe, it, expect, beforeEach, afterEach } from "bun:test";
+import { readFileSync } from "node:fs";
+import { join } from "node:path";
+import { createRunner } from "./tier1-command.ts";
+import {
+  setupTempDir,
+  cleanupTempDir,
+  getTempDir,
+  createFreshProject,
+  writeDoc,
+} from "./fixtures.ts";
+import { scanChanges } from "../../src/core/scanner.ts";
+import { getChangeDir } from "../../src/core/config.ts";
+
+describe("e2e: build 阶段", () => {
+  let runner: ReturnType<typeof createRunner>;
+
+  beforeEach(async () => {
+    await setupTempDir();
+    runner = createRunner();
+  });
+
+  afterEach(async () => {
+    await cleanupTempDir();
+  });
+
+  it("单任务执行，勾选并产出文件", async () => {
+    const config = await createFreshProject();
+    await writeDoc("auth", "task", "- [ ] 实现登录 API\n");
+
+    const result = await runner.runBuild(getTempDir(), "auth", config);
+
+    expect(result.files).toContain("task.md");
+    expect(result.files.length).toBeGreaterThanOrEqual(2);
+
+    const tasks = await scanChanges(getTempDir(), config);
+    expect(tasks[0].taskProgress).toEqual({ completed: 1, total: 1 });
+  });
+
+  it("多任务按顺序逐个勾选", async () => {
+    const config = await createFreshProject();
+    await writeDoc("multi-task", "task", `- [ ] 任务A\n- [ ] 任务B\n- [ ] 任务C\n`);
+
+    const result = await runner.runBuild(getTempDir(), "multi-task", config);
+
+    expect(result.files).toHaveLength(4);
+    expect(result.files).toContain("task.md");
+
+    const taskContent = readFileSync(
+      join(getChangeDir(getTempDir(), "multi-task"), "task.md"),
+      "utf-8",
+    );
+    expect(taskContent).toContain("- [x] 任务A");
+    expect(taskContent).toContain("- [x] 任务B");
+    expect(taskContent).toContain("- [x] 任务C");
+
+    const tasks = await scanChanges(getTempDir(), config);
+    expect(tasks[0].taskProgress).toEqual({ completed: 3, total: 3 });
+  });
+
+  it("空 task 清单时 taskProgress 提示无任务", async () => {
+    const config = await createFreshProject();
+    await writeDoc("empty", "task", "\n");
+
+    const changes = await scanChanges(getTempDir(), config);
+    const emptyChange = changes.find((c) => c.name === "empty");
+    expect(emptyChange).toBeDefined();
+    if (emptyChange) {
+      expect(emptyChange.taskProgress).toEqual({ completed: 0, total: 0 });
+    }
+  });
+
+  it("plan 未完成时 build 不可用", async () => {
+    const config = await createFreshProject();
+
+    await expect(runner.runBuild(getTempDir(), "no-task", config)).rejects.toThrow(
+      "task.md 不存在",
+    );
+  });
+
+  it("任务全部完成后状态为已完成", async () => {
+    const config = await createFreshProject();
+    await writeDoc("done", "task", "- [x] 已完成任务\n");
+
+    const result = await runner.runBuild(getTempDir(), "done", config);
+
+    expect(result.files).toEqual([]);
+
+    const tasks = await scanChanges(getTempDir(), config);
+    const doneChange = tasks.find((c) => c.name === "done");
+    expect(doneChange).toBeDefined();
+    if (doneChange) {
+      expect(doneChange.taskProgress).toEqual({ completed: 1, total: 1 });
+    }
+  });
+});