feat(agent): ② exec 自动放行（autoApproveExec）+ 抽出共享合并流程

- 新增 exec-merge.acceptAndMerge：封装 exec_review 通过并合并的完整流程
  （merge→冲突建补救任务/成功 decide+收口+回收），API decide 与 ingest 复用同一逻辑
- server.ts decide 改调 acceptAndMerge（去重 ~40 行内联逻辑）
- ingest result：auto-approved + autoApproveExec + 双复审 approve → fire-and-forget
  自动合并（git 异步不阻塞 tick）；冲突则补救任务 + 留 exec_review 人审
- 测试：acceptAndMerge 可合并→done、冲突→补救+留审核闸（真实 git repo）

至此 plan ① ② ③ 三类优化 + 通用规则 + L1-L4 记忆注入代码侧全部落地

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

src/api/server.ts

@@ -8,9 +8,8 @@ import type { Project, Autonomy } from '../model/types.js';
 import { syncProject, hasTodoJson } from '../sync/todo-sync.js';
 import { resolvedExecutorModels } from '../executor/models.js';
 import { classifyComplexity, type ClassifierFn } from '../executor/classify.js';
-import { mergeBranch } from '../executor/merge.js';
-import { git, removeWorktree, createWorktree } from '../executor/worktree.js';
-import { cleanupTaskRunArtifacts } from '../executor/cleanup.js';
+import { acceptAndMerge } from '../executor/exec-merge.js';
+import { createWorktree } from '../executor/worktree.js';
 import { resolveLogo, LOGO_MIME } from './logo.js';
 import { readTranscript, TranscriptError } from '../executor/transcript.js';
 import { createReadStream, createWriteStream, mkdirSync, readFileSync, statSync } from 'node:fs';
@@ -428,48 +427,14 @@ export function buildServer(opts: ApiOptions): FastifyInstance {
     const task = store.getTask(id);
     // merge:false = 仅通过不合并（逃生口：如目标分支正被用户工作区检出导致自动合并不可用）
     if (task && task.status === 'exec_review' && b.action === 'accept' && task.result?.branch && b.merge !== false) {
-      const project = store.getProject(task.projectId);
-      if (!project) throw new StoreError(`项目不存在: ${task.projectId}`);
-      const { branch, worktree } = task.result;
-      const mr = await mergeBranch(project.repoPath, branch, project.defaultBranch, task.id);
-      if (!mr.ok) {
-        // 自动合并失败（多为冲突）→ 建/复用最高优先级补救任务来完成合并，原任务留在审核闸
-        const rem = store.ensureMergeRemediationTask(task.id, {
-          branch, targetBranch: project.defaultBranch,
-          conflictError: mr.error ?? '未知冲突', conflictFiles: mr.conflictFiles,
-        });
-        throw new StoreError(`合并失败：${mr.error}（原任务保留在审核闸；已建最高优先级补救任务 ${rem.id}「${rem.title}」来完成合并）`);
+      const outcome = await acceptAndMerge(store, app.log, task, b.actor ?? 'user');
+      if (!outcome.ok) {
+        if (outcome.remediationTaskId) {
+          const rem = store.getTask(outcome.remediationTaskId);
+          throw new StoreError(`合并失败：${outcome.error}（原任务保留在审核闸；已建最高优先级补救任务 ${rem?.id}「${rem?.title}」来完成合并）`);
+        }
+        throw new StoreError(`合并失败：${outcome.error}`);
       }
-
-      store.decide(id, 'accept', b.actor ?? 'user', b.reason ?? null);
-      // 合并产物记录：复用 prUrl 字段写 merged:<mergeCommit>
-      store.setResult(id, { ...task.result, prUrl: `merged:${mr.mergeCommit}` });
-      // 即时回收 runs/<runId>/（job/outbox/heartbeat 已无价值；转录保留供排查）。
-      // 任务此刻已 done（终态），cleanupTaskRunArtifacts 内部据此放行；同步删（纯本地 fs，快）。
-      const reclaimed = cleanupTaskRunArtifacts(store, id, app.log);
-      if (reclaimed) app.log.info(`任务 ${id} 合并后回收 ${reclaimed} 个 run 工作目录`);
-      // 补救完成自动收口：若本任务是某原任务的「合并冲突补救」任务，合并成功后把原任务也标 done
-      const origin = store.findMergeOriginTask(id);
-      if (origin) {
-        try {
-          store.remediateOrigin(origin.id, id, mr.mergeCommit);
-        } catch (e) {
-          app.log.error(`补救任务 ${id} 合并后收口原任务 ${origin.id} 失败（不影响本任务结果）：${(e as Error).message}`);
-        }
-      }
-      // 异步回收：执行 worktree + 已合并的任务分支（失败只记日志，不影响响应）
-      void (async () => {
-        try {
-          if (worktree) await removeWorktree(project.repoPath, worktree);
-        } catch (e) {
-          app.log.error(`任务 ${id} 合并后清理 worktree 失败（不影响结果）：${(e as Error).message}`);
-        }
-        try {
-          await git(project.repoPath, ['branch', '-d', branch]);
-        } catch (e) {
-          app.log.error(`任务 ${id} 合并后删除分支 ${branch} 失败（不影响结果）：${(e as Error).message}`);
-        }
-      })();
       return store.getTask(id);
     }