新增: 多Agent数据层(V36迁移+3新表+Repo CRUD+7个测试全绿)

- V36: ai_plans/ai_subtasks/ai_conflicts 3 新表 + ai_messages/ai_tool_executions 加 subtask_id

- models: PlanRecord/SubTaskRecord/ConflictRecord 结构体

- PlanRepo/SubTaskRepo/ConflictRepo CRUD(insert/get/list_by_*/update_status/resolve)

- 7个 Repo 单元测试全部通过(内存 SQLite + 全迁移)

- 顺带修复 task_repo.rs 预存测试编译错误(trec_full 参数类型+缺失 await)

crates/df-storage/src/migrations.rs

@@ -45,7 +45,7 @@ pub fn run(conn: &Connection) -> Result<()> {
     //       什么数据库、Redis 在哪、有没有 MQ"的基础设施上下文。
     // V33 = 审批重启恢复:ai_conversations 加 pending_approvals TEXT 列,持久化挂起审批快照,
     //       重启后从 DB 恢复 pending_approvals 内存态,使待审批不丢。
-    let steps: [(i32, fn(&Connection) -> Result<()>); 35] = [
+    let steps: [(i32, fn(&Connection) -> Result<()>); 36] = [
         (1, migrate_v1),
         (2, migrate_v2),
         (3, migrate_v3),
@@ -81,6 +81,7 @@ pub fn run(conn: &Connection) -> Result<()> {
         (33, migrate_v33),
         (34, migrate_v34),
         (35, migrate_v35),
+        (36, migrate_v36),
     ];
 
     for (version, migrate_fn) in steps {
@@ -1030,6 +1031,90 @@ fn migrate_v35(conn: &Connection) -> Result<()> {
     Ok(())
 }
 
+/// V36:多 Agent 并行执行数据层(ai_plans/ai_subtasks/ai_conflicts 3 新表 +
+/// ai_messages/ai_tool_executions 加 subtask_id 列)。
+/// 设计依据:docs/02-架构设计/专项设计/多Agent并行执行与仲裁合并设计-2026-07-01.md §二
+fn migrate_v36(conn: &Connection) -> Result<()> {
+    // 1. ai_messages 加 subtask_id 列(消息归属子任务,NULL=单 Agent 时期)
+    if !column_exists(conn, "ai_messages", "subtask_id") {
+        conn.execute("ALTER TABLE ai_messages ADD COLUMN subtask_id TEXT", [])?;
+        tracing::info!("v36: ai_messages 加 subtask_id 列");
+    }
+
+    // 2. ai_tool_executions 加 subtask_id 列(工具调用归属子任务)
+    if !column_exists(conn, "ai_tool_executions", "subtask_id") {
+        conn.execute("ALTER TABLE ai_tool_executions ADD COLUMN subtask_id TEXT", [])?;
+        tracing::info!("v36: ai_tool_executions 加 subtask_id 列");
+    }
+
+    // 3. ai_plans 表(Plan 生命周期:用户消息触发→拆解→执行→合并→完成)
+    conn.execute(
+        "CREATE TABLE IF NOT EXISTS ai_plans (
+            id              TEXT PRIMARY KEY,
+            conversation_id TEXT NOT NULL,
+            user_message_id TEXT,
+            status          TEXT NOT NULL DEFAULT 'planning',
+            subtask_count   INTEGER NOT NULL DEFAULT 0,
+            created_at      TEXT NOT NULL,
+            completed_at    TEXT
+        )",
+        [],
+    )?;
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_ai_plans_conv ON ai_plans(conversation_id, created_at)",
+        [],
+    )?;
+
+    // 4. ai_subtasks 表(SubTask 状态 + DAG 层级 + Git worktree 分支)
+    conn.execute(
+        "CREATE TABLE IF NOT EXISTS ai_subtasks (
+            id          TEXT PRIMARY KEY,
+            plan_id     TEXT NOT NULL REFERENCES ai_plans(id),
+            persona_id  TEXT,
+            intent      TEXT NOT NULL DEFAULT '',
+            status      TEXT NOT NULL DEFAULT 'pending',
+            layer       INTEGER NOT NULL DEFAULT 0,
+            deps        TEXT,
+            branch      TEXT,
+            created_at  TEXT NOT NULL,
+            completed_at TEXT
+        )",
+        [],
+    )?;
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_ai_subtasks_plan ON ai_subtasks(plan_id, layer)",
+        [],
+    )?;
+
+    // 5. ai_conflicts 表(合并冲突:同文件路径 + 跨文件语义冲突)
+    conn.execute(
+        "CREATE TABLE IF NOT EXISTS ai_conflicts (
+            id            TEXT PRIMARY KEY,
+            plan_id       TEXT NOT NULL REFERENCES ai_plans(id),
+            file_path     TEXT NOT NULL DEFAULT '',
+            conflict_type TEXT NOT NULL DEFAULT 'file',
+            subtask_a     TEXT,
+            subtask_b     TEXT,
+            diff_a        TEXT,
+            diff_b        TEXT,
+            resolution    TEXT NOT NULL DEFAULT 'pending',
+            resolved_by   TEXT,
+            created_at    TEXT NOT NULL,
+            resolved_at   TEXT
+        )",
+        [],
+    )?;
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS idx_ai_conflicts_plan ON ai_conflicts(plan_id, resolution)",
+        [],
+    )?;
+
+    tracing::info!("v36: 建 ai_plans/ai_subtasks/ai_conflicts 表 + subtask_id 列(多 Agent 并行执行数据层)");
+    conn.execute("INSERT INTO schema_version (version) VALUES (?)", [36])?;
+    tracing::info!("迁移 v36 完成");
+    Ok(())
+}
+
 /// V21 建表 SQL — 消息拆分存储 ai_messages 表
 ///
 /// 与 V9_SQL 中的 ai_messages 镜像(V9 给新库,此 const 给老库 V21 迁移用 IF NOT EXISTS)。