feat: 线程等待与状态读取 8 项（wait/read/message/handoff/worktree/pr-checks/automation/sleep）

对照 Codex app：wait_threads 首变+afterCursor+8上限、
read_thread 详情摘要、send_message_to_thread 复活失败任务、
handoff 登记与上报轮询、worktree 派生状态、PR checks JSON+
check-runs 日志与注释、automation GET/PATCH、clock.sleep
（API+host）。诚实边界见 docs/thread-wait-ops.md：无
worktree 阶段流、无 automation 变化静默、无独立测试结果
记录、handoff 服务端不执行迁移、wait 仅数据库级变化检测。

三套件：cloud 940 OK（4 跳过）、host 91 OK、deploy 29 OK

cloud/automations.py

@@ -324,6 +324,65 @@ def cancel_automation(conn, automation_id, now=None):
     return True, automation_to_dict(row, now)
 
 
+def update_automation(conn, automation_id, fields, now=None):
+    """更新自动化定义（automation_update）：fields 只认
+    name / prompt / interval_seconds / repo_url 四个键，
+    其它键一律忽略（不报错、不存入，避免调用方拼错字段
+    名后以为已改）；四个键全没给时抛 ValueError（空更新
+    不是成功）。校验与创建同款（_validate_fields，名字
+    仍按“同项目 active 名字唯一”查重，改名撞名时 400）。
+
+    返回 (ok, auto)：行不存在时 (False, None)；已取消时
+    (False, 旧 dict)——取消是终态，改已取消的定义必须
+    重建，不能靠 update 复活（与 cancel 的软删除语义
+    一致）。成功时 commit。注意：更新不重置 last_run_at /
+    last_claimed_at——改间隔只影响下一次到期判断（next_run
+    由 last_run_at + 新间隔算），不立即触发一轮；想立即
+    跑一轮应走执行器的 claim 路径，不是改定义。"""
+    if now is None:
+        now = time.time()
+    ensure_automations_tables(conn)
+    row = conn.execute(
+        "SELECT * FROM automations WHERE id = ?", (automation_id,)
+    ).fetchone()
+    if row is None:
+        return False, None
+    row = _row_dict(row, AUTOMATION_COLUMNS)
+    if row["status"] != ACTIVE:
+        return False, automation_to_dict(row, now)
+    if not isinstance(fields, dict):
+        raise ValueError("fields must be an object")
+    current = automation_to_dict(row, now)
+    name = fields.get("name", current["name"])
+    prompt = fields.get("prompt", current["prompt"])
+    interval = fields.get("interval_seconds",
+                          current["interval_seconds"])
+    repo_url = fields.get("repo_url", current["repo_url"])
+    if not any(k in fields for k in (
+            "name", "prompt", "interval_seconds", "repo_url")):
+        raise ValueError("no updatable field given")
+    name, prompt, interval, repo_url = _validate_fields(
+        name, prompt, interval, repo_url)
+    if name != current["name"]:
+        clash = conn.execute(
+            "SELECT id FROM automations WHERE project_id = ?"
+            " AND name = ? AND status = ? AND id != ?",
+            (row["project_id"], name, ACTIVE, automation_id)
+        ).fetchone()
+        if clash is not None:
+            raise ValueError(
+                "automation name already exists in this project")
+    conn.execute(
+        "UPDATE automations SET name = ?, prompt = ?,"
+        " interval_seconds = ?, repo_url = ? WHERE id = ?",
+        (name, prompt, interval, repo_url, automation_id))
+    conn.commit()
+    row = conn.execute(
+        "SELECT * FROM automations WHERE id = ?", (automation_id,)
+    ).fetchone()
+    return True, automation_to_dict(row, now)
+
+
 def due_automations(conn, project_id, now=None):
     """列出某项目当前到期的 active 定义(纯读，不抢单)。
     SQL 层算到期：从未跑过(last_run_at 为空)或上次执行距