feat(agent): L1 记忆注入——重试任务带上次失败原因喂回 prompt

- store.lastRunErrorOf(taskId)：取最近一次失败 run 的 error（任意 kind）
- orchestrator.claimOne：写 job.json 时填充 task.lastRunError 下发 worker
- runner 三处 prompt（executor/planner/conflict）注入「## 上次失败原因」段（截断 2000 字符）

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

test/memory-l1.test.ts

@@ -0,0 +1,59 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { buildPrompt, buildPlannerPrompt, buildConflictPrompt } from '../src/executor/runner.js';
+import { Store } from '../src/store/index.js';
+import type { Task } from '../src/model/types.js';
+
+function fakeTask(over: Partial<Task> = {}): Task {
+  return {
+    id: 'tsk_x', title: '改个东西', complexity: 'medium', depth: 1,
+    operations: '把 A 改成 B', spec: null, plan: null, deps: [],
+    ...over,
+  } as Task;
+}
+
+const SECTION = '上次失败原因';
+
+test('L1: 无 lastRunError 时三处 prompt 都不含「上次失败原因」段', () => {
+  const t = fakeTask();
+  assert.ok(!buildPrompt(t).includes(SECTION));
+  assert.ok(!buildPlannerPrompt(fakeTask({ complexity: 'medium' }), 'spec').includes(SECTION));
+  assert.ok(!buildPlannerPrompt(fakeTask({ complexity: 'hard' }), 'decompose').includes(SECTION));
+  assert.ok(!buildConflictPrompt(t, ['a.ts']).includes(SECTION));
+});
+
+test('L1: 有 lastRunError 时三处 prompt 注入失败原因', () => {
+  const err = 'verify 失败：npm test 退出码 1\nFAIL src/foo.test.ts';
+  const t = fakeTask({ lastRunError: err });
+  for (const p of [
+    buildPrompt(t),
+    buildPlannerPrompt(fakeTask({ complexity: 'medium', lastRunError: err }), 'spec'),
+    buildPlannerPrompt(fakeTask({ complexity: 'hard', lastRunError: err }), 'decompose'),
+    buildConflictPrompt(t, ['a.ts']),
+  ]) {
+    assert.ok(p.includes(SECTION), '应含失败段标题');
+    assert.ok(p.includes('npm test 退出码 1'), '应含具体错误');
+  }
+});
+
+test('L1: 超长错误被截断到 2000 字符', () => {
+  const err = 'X'.repeat(5000);
+  const p = buildPrompt(fakeTask({ lastRunError: err }));
+  assert.ok(p.includes('已截断'));
+  assert.ok(!p.includes('X'.repeat(2100)));
+});
+
+test('lastRunErrorOf 取最近一次失败 run 的错误（任意 kind）', () => {
+  const s = new Store(':memory:');
+  const p = s.createProject({ name: 'l1', repoPath: '/tmp/l1-' + Math.random() });
+  const t = s.createTask({ projectId: p.id, title: 'feat', complexity: 'easy' });
+  assert.equal(s.lastRunErrorOf(t.id), null, '无失败 run → null');
+
+  s.setOperations(t.id, 'do it');
+  s.transition(t.id, 'queued');
+  s.transition(t.id, 'executing');
+  const run = s.startRun(t.id, 'executor', { worktree: '/tmp/w', branch: 'b' });
+  s.failTaskAttempt(t.id, run.id, '第一次失败：编译错误');
+  assert.equal(s.lastRunErrorOf(t.id), '第一次失败：编译错误');
+  s.close();
+});