diff --git a/src-tauri/src/commands/gitea.rs b/src-tauri/src/commands/gitea.rs
index e935f99..1c52842 100644
--- a/src-tauri/src/commands/gitea.rs
+++ b/src-tauri/src/commands/gitea.rs
@@ -549,6 +549,11 @@ pub fn poll_all_repos() -> Result<(usize, usize), String> {
             &format!("PR 轮询新采集 {pr_ingested} 条事件"), None);
     }
 
+    // staleness 自知：至少成功拉到一个仓库才算一次有效同步
+    if polled > 0 {
+        crate::db::touch_sync_state(&conn, "flywheel");
+    }
+
     Ok((polled, ingested))
 }
 
diff --git a/src-tauri/src/db.rs b/src-tauri/src/db.rs
index 2e81c9e..f8d0557 100644
--- a/src-tauri/src/db.rs
+++ b/src-tauri/src/db.rs
@@ -564,6 +564,14 @@ fn migrate(conn: &rusqlite::Connection) {
         CREATE INDEX IF NOT EXISTS idx_pr_events_project ON pr_events(project_id);
     ").expect("create pr_events table");
 
+    // 飞轮同步状态（staleness 自知：派生数据类 MCP 工具据此标注数据新鲜度）
+    conn.execute_batch("
+        CREATE TABLE IF NOT EXISTS sync_state (
+            domain    TEXT PRIMARY KEY,
+            synced_at TEXT NOT NULL DEFAULT (datetime('now'))
+        );
+    ").expect("create sync_state table");
+
     // 仪表盘全局快启应用（无项目 FK 约束）
     conn.execute_batch("
         CREATE TABLE IF NOT EXISTS global_tools (
@@ -909,6 +917,26 @@ pub fn conn_with_schema() -> rusqlite::Connection {
     conn
 }
 
+/// 记录某数据域最近一次成功同步时间（upsert）。失败时静默（同步标记不能反噬业务逻辑）
+pub fn touch_sync_state(conn: &rusqlite::Connection, domain: &str) {
+    let _ = conn.execute(
+        "INSERT INTO sync_state (domain, synced_at) VALUES (?1, datetime('now'))
+         ON CONFLICT(domain) DO UPDATE SET synced_at = datetime('now')",
+        rusqlite::params![domain],
+    );
+}
+
+/// 读取某数据域最近同步时间与距今分钟数；无记录返回 None
+pub fn read_sync_state(conn: &rusqlite::Connection, domain: &str) -> Option<(String, i64)> {
+    conn.query_row(
+        "SELECT synced_at, CAST((julianday('now') - julianday(synced_at)) * 1440 AS INTEGER)
+         FROM sync_state WHERE domain = ?1",
+        rusqlite::params![domain],
+        |r| Ok((r.get(0)?, r.get(1)?)),
+    )
+    .ok()
+}
+
 /// 写入运行时日志。失败时静默（不能让日志写入反过来崩溃业务逻辑）
 pub fn log_event(category: &str, level: &str, message: &str, context: Option<&str>) {
     let pool = match POOL.get() {
@@ -946,6 +974,27 @@ mod tests {
         migrate(&conn);
     }
 
+    #[test]
+    fn sync_state_touch_then_read() {
+        let conn = conn_with_schema();
+        touch_sync_state(&conn, "flywheel");
+        let (at, mins) = read_sync_state(&conn, "flywheel").expect("应有同步记录");
+        assert!(!at.is_empty());
+        assert!(mins >= 0 && mins < 2, "刚 touch 的记录距今应为 0~1 分钟，实际 {mins}");
+        // upsert：重复 touch 不报错、仍只有一行
+        touch_sync_state(&conn, "flywheel");
+        let count: i64 = conn
+            .query_row("SELECT COUNT(*) FROM sync_state WHERE domain='flywheel'", [], |r| r.get(0))
+            .unwrap();
+        assert_eq!(count, 1);
+    }
+
+    #[test]
+    fn sync_state_unknown_domain_returns_none() {
+        let conn = conn_with_schema();
+        assert!(read_sync_state(&conn, "nonexistent").is_none());
+    }
+
     #[test]
     fn core_tables_exist() {
         let conn = conn_with_schema();
diff --git a/src-tauri/src/mcp_tools.rs b/src-tauri/src/mcp_tools.rs
index 3ea0e9c..7451e83 100644
--- a/src-tauri/src/mcp_tools.rs
+++ b/src-tauri/src/mcp_tools.rs
@@ -468,10 +468,16 @@ pub async fn tools_call(params: Option<&Value>) -> Value {
                     format!("{icon} PR #{num} [{action}] {title}\n   {head} → {base} by {author} @ {at}")
                 })
                 .collect();
+            let fresh_line = match db::read_sync_state(&conn, "flywheel") {
+                Some((at, mins)) => format!(
+                    "⏱ 飞轮数据最近同步：{at} UTC（约 {mins} 分钟前）。数据可能滞后——PR 是否已存在以 create_pull_request 返回的 already_exists 为准。\n\n"
+                ),
+                None => "⏱ 飞轮数据同步时间未知（尚无同步记录，可先调 poll_now）。\n\n".to_string(),
+            };
             if rows.is_empty() {
-                Ok(format!("项目 {} 暂无 PR 事件记录", pid))
+                Ok(format!("{fresh_line}项目 {} 暂无 PR 事件记录", pid))
             } else {
-                Ok(format!("PR 事件（最近 {} 条）：\n\n{}", rows.len(), rows.join("\n\n")))
+                Ok(format!("{fresh_line}PR 事件（最近 {} 条）：\n\n{}", rows.len(), rows.join("\n\n")))
             }
         }
         "get_commit_metrics" => {
@@ -509,6 +515,12 @@ pub async fn tools_call(params: Option<&Value>) -> Value {
                 )
                 .unwrap_or(0);
             let mut out = format!("## 提交飞轮数据（最近 {} 天）\n\n", days);
+            match db::read_sync_state(&conn, "flywheel") {
+                Some((at, mins)) => out.push_str(&format!(
+                    "⏱ 飞轮数据最近同步：{at} UTC（约 {mins} 分钟前）\n\n"
+                )),
+                None => out.push_str("⏱ 飞轮数据同步时间未知（尚无同步记录，可先调 poll_now）\n\n"),
+            }
             out.push_str(&format!("- **总提交数**：{}\n", total));
             out.push_str(&format!(
                 "- **返工提交**：{} 条（{:.0}%）\n",
diff --git a/src-tauri/src/mcp_webhook.rs b/src-tauri/src/mcp_webhook.rs
index 116c70d..46d52bb 100644
--- a/src-tauri/src/mcp_webhook.rs
+++ b/src-tauri/src/mcp_webhook.rs
@@ -151,6 +151,9 @@ async fn handle_push(project_id: &str, body: &Bytes) -> Response {
             received += 1;
         }
     }
+    if received > 0 {
+        db::touch_sync_state(&conn, "flywheel");
+    }
     log_event(
         "gitea_webhook",
         "info",
@@ -215,6 +218,7 @@ async fn handle_pull_request(project_id: &str, body: &Bytes) -> Response {
 
     match result {
         Ok(_) => {
+            db::touch_sync_state(&conn, "flywheel");
             log_event(
                 "gitea_webhook",
                 "info",