```

feat(learning): 添加技能学习候选者合成锁定机制

添加了 DraftSynthesisInProgress 和 DraftHasNoChanges 异常来处理并发场景，
确保同一技能学习候选者的合成过程不会重复执行。实现了 claim_learning_candidate_for_synthesis
方法来原子性地锁定候选者进行合成。

fix(web): 为技能草案创建端点添加适当的HTTP状态码

当草案没有变化或正在合成时，现在正确返回409状态码而不是内部错误。

feat(skills): 实现技能修订内容比较以检测无变化情况

添加了 _is_noop_revision 方法来比较基础技能和提议的修订，
如果内容没有实际变化则抛出 NoDraftChanges 异常。

refactor(process): 修复任务证据记录后根运行状态更新逻辑

将任务证据记录事件后的状态从 waiting 更改为 done，并设置 finished_at 时间戳。

feat(tools): 防止在同一运行中重复执行外部写入操作

为邮件发送、日历创建等外部写入工具添加去重机制，避免重复的外部操作。

test: 添加技能学习和工具执行的单元测试

增加测试用例验证并发草案合成、重复外部写入抑制和无变化修订检测等功能。
```

app-instance/backend/tests/unit/test_process_projection.py

@@ -363,6 +363,52 @@ def test_process_projection_emits_tool_cards_from_run_messages(tmp_path: Path) -
     assert tool_result["metadata"]["success"] is True
 
 
+def test_process_projection_marks_root_done_when_result_is_ready(tmp_path: Path) -> None:
+    session = SessionManager(tmp_path)
+    run_store = RunMemoryStore(tmp_path / "memory" / "runs")
+    run_store.append_run_record(
+        RunRecord(
+            run_id="main-run",
+            session_id="web:test",
+            task_id="task-1",
+            attempt_index=1,
+            task_text="send email",
+            started_at="2026-01-01T00:00:03+00:00",
+            ended_at="2026-01-01T00:00:04+00:00",
+            success=True,
+            finish_reason="stop",
+        )
+    )
+    session.append_message(
+        "web:test",
+        role="system",
+        event_type="task_execution_planned",
+        event_payload={"task_id": "task-1", "attempt_index": 1, "plan_mode": "single", "strategy": "single"},
+        context_visible=False,
+    )
+    session.append_message(
+        "web:test",
+        role="system",
+        event_type="task_synthesis_completed",
+        event_payload={"task_id": "task-1", "attempt_index": 1, "main_run_id": "main-run"},
+        context_visible=False,
+    )
+    session.append_message(
+        "web:test",
+        run_id="main-run",
+        role="system",
+        event_type="task_evidence_recorded",
+        event_payload={"task_id": "task-1", "attempt_index": 1, "evidence_status": "recorded"},
+        context_visible=False,
+    )
+
+    projection = SessionProcessProjector(session, run_store).project("web:test")
+
+    root_run = next(run for run in projection["runs"] if run["run_id"] == "task:task-1:attempt:1")
+    assert root_run["status"] == "done"
+    assert root_run["finished_at"] is not None
+
+
 def test_process_projection_exposes_ephemeral_guidance_artifacts(tmp_path: Path) -> None:
     session = SessionManager(tmp_path)
     run_store = RunMemoryStore(tmp_path / "memory" / "runs")