feat: attempt ledger + resume preamble (v6)

Foundry 'platform restarts with original input' gap, after
reading the existing mechanisms: creation idempotency
(UNIQUE project_id+idempotency_key), goal checkpoints
(task_checkpoints per round, same-thread breakpoint resume
with no-progress fuse), merge/cost/notification CAS, and
coordinator child reuse already exist. The uncovered segment
is non-goal platform-interrupted tasks: auto_resume requeues
them fresh in the same worktree after clearing result/error/
interrupted_reason, so the new run gets only the original
prompt and cannot tell what the previous attempt had done.

This track adds, in worker/server layer only (no host.py or
codex thread change): task_attempts ledger, recorded by
auto_resume_interrupted in the same transaction before
clearing (attempt_no = old auto_resume_count + 1, kind
goal_breakpoint|platform_fresh, interrupted_reason,
checkpoint_round, result/error truncated to 2000 chars,
INSERT OR IGNORE keeps the first record on duplicate);
resume preamble injected in-memory only at claim for
platform_fresh reruns (previous attempt facts, truncated to
1000 chars, plus check-worktree-first and verify-before-
recreating-external-artifacts instructions; skipped for
coordinator/_resume/breakpoint tasks and when no record
exists, never fabricated); attempts surfaced read-only in
GET /tasks/{id}/timeline under existing project-read
permission. Fresh PG schema, migrations table list, and
server/worker ensure paths share one DDL.

Deliberately NOT claimed: the preamble is an instruction,
not a hard guarantee like creation idempotency or merge
CAS; the ledger does not track worktree files or external
artifacts (no worktree snapshot, executor-dependent paths;
hard dedup for those still rests on their existing gates);
manual retry paths do not go through auto_resume, so they
get no ledger record or preamble. Tests:
test_attempts.py (7 tests).

cloud/worker.py

@@ -137,6 +137,10 @@ from types import SimpleNamespace
 from cloud.agent_def import AgentDefinition as _AgentDefinition
 from cloud.agent_def import format_instructions_header as _agent_header
 from cloud.agent_def import missing_required_tools as _missing_tools
+from cloud.attempts import build_resume_preamble as _resume_preamble
+from cloud.attempts import ensure_attempts_table as _ensure_attempts
+from cloud.attempts import latest_attempt as _latest_attempt
+from cloud.attempts import record_attempt as _record_attempt
 from cloud.auth import AuthStore
 from cloud.coordinator import build_report as _coord_build_report
 from cloud.coordinator import DEFAULT_POLL_INTERVAL as _COORD_POLL_INTERVAL
@@ -1025,7 +1029,9 @@ class Worker:
                     " model, interrupted_reason, resume_after,"
                     " auto_resume_stall_count,"
                     " checkpoint_round_at_last_resume,"
-                    " goal_mode, verify_command, goal FROM tasks"
+                    " goal_mode, verify_command, goal,"
+                    " result_text, error_text, auto_resume_count"
+                    " FROM tasks"
                     " WHERE status = 'interrupted'"
                     " AND (paused_by_user IS NULL OR paused_by_user = 0)"
                     " AND (interrupted_reason IS NULL OR"
@@ -1093,6 +1099,24 @@ class Worker:
                         # 消息，防它劫持新跑的 prompt。
                         resume_set = ("goal_resume_pending = 0,"
                                       " resume_message = NULL")
+                    # 尝试账本（v6）：清掉旧结果之前，先把正结束
+                    # 的这次尝试记下来；记账与回 queued 在同一
+                    # 事务里提交。attempt_no = 旧 auto_resume_count
+                    # + 1，即正结束尝试的序号；kind 按 goal 与否
+                    # 分断点续跑与平台全新重排。记账失败不单独
+                    # 炸恢复循环——外层已兜底，但本轮仍继续回
+                    # queued（账本缺一条记录好过任务卡住不恢复；
+                    # 认领时查不到账本即不贴前言，不编造）。
+                    try:
+                        _ensure_attempts(conn)
+                        _record_attempt(
+                            conn, task_id,
+                            (row[14] or 0) + 1,
+                            "goal_breakpoint" if is_goal
+                            else "platform_fresh",
+                            row[5], cp_round, row[12], row[13])
+                    except Exception:
+                        pass
                     cur = conn.execute(
                         "UPDATE tasks SET status = 'queued', "
                         + resume_set +
@@ -1528,6 +1552,12 @@ class Worker:
                 "summary TEXT, "
                 "state_sha TEXT, "
                 "created_at DOUBLE PRECISION)")
+            # 尝试账本（v6，见 cloud/attempts.py）：worker 直连
+            # 老库时也补，与 server ensure 同 DDL。
+            try:
+                _ensure_attempts(conn)
+            except Exception:
+                pass
             conn.execute(
                 "CREATE INDEX IF NOT EXISTS idx_task_steps_task"
                 " ON task_steps(task_id, step_no)")
@@ -1920,6 +1950,45 @@ class Worker:
                     task["id"])
         return new_task
 
+    def _apply_resume_preamble(self, task):
+        """重跑前言注入（v6，见 cloud/attempts.py）：只改内存副本。
+
+        跳过：协调员任务、_resume 任务、断点续跑任务（已有
+        会话连续性）、auto_resume_count 为 0 的首轮任务、账本
+        里查不到记录的老任务、最新尝试不是 platform_fresh
+        的任务（goal 断点续跑走线程连续性，不贴前言）。
+        贴法与项目注入同款：前言 + 原 prompt，goal 任务若
+        意外走到这里也同步贴 goal（执行器取 goal 优先于
+        prompt）；查账本失败时原样返回，不炸认领。
+        """
+        if task.get("coordinator_parts"):
+            return task
+        if task.get("_resume") or task.get("_goal_resume_breakpoint"):
+            return task
+        if not task.get("auto_resume_count"):
+            return task
+        try:
+            conn = _db_connect(self.db_path)
+            try:
+                attempt = _latest_attempt(conn, task["id"])
+            finally:
+                conn.close()
+        except Exception:
+            return task
+        preamble = _resume_preamble(attempt)
+        if not preamble:
+            return task
+        new_task = dict(task)
+        new_task["prompt"] = preamble + "\n\n" + (
+            task.get("prompt") or "")
+        if task.get("goal_mode") or task.get("verify_command"):
+            new_task["goal"] = preamble + "\n\n" + (
+                task.get("goal") or task.get("prompt") or "")
+        new_task["_resume_preamble_injected"] = True
+        self._audit(task["project_id"], "worker_resume_preamble_injected",
+                    task["id"])
+        return new_task
+
     def _tree_snapshot_source(self, task):
         """首轮目录树快照的宿主侧来源目录，或 None。
 
@@ -5742,6 +5811,9 @@ class Worker:
         # _apply_project_injection 的跳过规则；只改内存副本；
         # 最后贴，排在待办与记忆之前（最通用上下文在最前）。
         task = self._apply_project_injection(task)
+        # 重跑前言：平台全新重排的任务在项目注入之后贴，离原
+        # prompt 最近；只改内存副本，原 prompt 不落库。
+        task = self._apply_resume_preamble(task)
         self._audit(task["project_id"], "worker_claim",
                     "%s executor=%s" % (task_id, self._executor_name()))
         # log_event 只接受 task_id/project_id/status/message 四个