feat(trigger): 新增"任务创建"触发机制(on_task_create)

自定义 agent 触发条件从 5 种扩展到 6 种,新增任务被创建时触发。
用 tasks.id 单调水位线 + scheduler_state 防重复,重启不补触发;
触发消息完整分行给出任务ID/描述/目标。DB 加列并带 ALTER 迁移。

Co-Authored-By: Claude Opus 4.8 <[email protected]>

db/schema.sql

@@ -457,11 +457,13 @@ CREATE TABLE IF NOT EXISTS agent_triggers (
     on_goal_met                 BOOLEAN NOT NULL DEFAULT false,
     on_task_timeout             BOOLEAN NOT NULL DEFAULT false,
     on_tool_call                BOOLEAN NOT NULL DEFAULT false,
+    on_task_create              BOOLEAN NOT NULL DEFAULT false,
     interval_message            TEXT NOT NULL DEFAULT '',
     finding_message             TEXT NOT NULL DEFAULT '',
     goal_message                TEXT NOT NULL DEFAULT '',
     task_timeout_message        TEXT NOT NULL DEFAULT '',
     tool_call_message           TEXT NOT NULL DEFAULT '',
+    task_create_message         TEXT NOT NULL DEFAULT '',
     tool_names                  TEXT NOT NULL DEFAULT '',
     last_fire                   TIMESTAMPTZ,
     created_at                  TIMESTAMPTZ NOT NULL DEFAULT now(),
@@ -469,9 +471,11 @@ CREATE TABLE IF NOT EXISTS agent_triggers (
 );
 CREATE INDEX IF NOT EXISTS idx_agent_triggers_agent ON agent_triggers(agent_key);
 -- 加列迁移(已发版,旧库升级补列;新库 CREATE 已含这些列,ALTER 为 no-op)。幂等,每次启动可重复执行。
-ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS on_tool_call      BOOLEAN NOT NULL DEFAULT false;
-ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS tool_call_message TEXT    NOT NULL DEFAULT '';
-ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS tool_names        TEXT    NOT NULL DEFAULT '';
+ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS on_tool_call        BOOLEAN NOT NULL DEFAULT false;
+ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS tool_call_message   TEXT    NOT NULL DEFAULT '';
+ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS tool_names          TEXT    NOT NULL DEFAULT '';
+ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS on_task_create      BOOLEAN NOT NULL DEFAULT false;
+ALTER TABLE agent_triggers ADD COLUMN IF NOT EXISTS task_create_message TEXT    NOT NULL DEFAULT '';
 DROP TRIGGER IF EXISTS trg_agent_triggers_upd ON agent_triggers;
 CREATE TRIGGER trg_agent_triggers_upd BEFORE UPDATE ON agent_triggers
     FOR EACH ROW EXECUTE FUNCTION set_updated_at();