diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/action_execution.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/action_execution.rs
index 5eead20f3..c85d9c1df 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/action_execution.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/action_execution.rs
@@ -544,18 +544,16 @@ fn append_agent_runtime_file_read_source_action_id(
     let Some(action_id) = action_id.map(str::trim).filter(|value| !value.is_empty()) else {
         return;
     };
-    let Some(detail) = observation.detail.as_deref() else {
-        return;
-    };
-    let Some(first) = detail.lines().next() else {
-        return;
-    };
-    if first.contains("sourceActionId=") {
+    if observation.summary.contains("sourceActionId=") {
         return;
     }
-    let rest = detail[first.len()..].to_string();
-    let first = first.to_string();
-    observation.detail = Some(format!("{first} · sourceActionId={action_id}{rest}"));
+    // 写进 **summary** 而不是 detail：`file.read` 的 detail 在投影给模型和事件流之前
+    // 会被换成 durable receipt 的 safe_detail（只有 path / contentSha256 / lines 三个
+    // 字段），追加在 detail 上的字段到不了模型手里。实测一次 run 里模型照着新指令
+    // 满世界找 sourceActionId、一次也没看到，只能反复重读全文再猜 actionId，28 次
+    // file.read、5 次 acceptance_update 才收敛。summary 是原样保留的，也没有任何
+    // 解析方依赖它的形状。
+    observation.summary = format!("{} · sourceActionId={action_id}", observation.summary);
 }
 
 pub(in crate::agent) fn observe_agent_runtime_project_snapshot_with_lock<F>(
@@ -935,12 +933,14 @@ mod file_read_source_action_id_tests {
             &mut observation,
             Some("action-0123456789abcdef01234567"),
         );
+        assert!(
+            observation
+                .summary
+                .ends_with("· sourceActionId=action-0123456789abcdef01234567"),
+            "actionId 必须写在 summary 上——detail 会被换成 safe_detail，到不了模型手里"
+        );
         let detail = observation.detail.clone().expect("detail");
-        assert!(detail
-            .lines()
-            .next()
-            .expect("first line")
-            .ends_with("· sourceActionId=action-0123456789abcdef01234567"));
+        assert!(!detail.contains("sourceActionId="), "detail 保持原样");
         assert!(detail.contains("第一行内容"), "首行之后的内容必须保留");
 
         let root = std::env::temp_dir();
@@ -958,19 +958,19 @@ mod file_read_source_action_id_tests {
     fn appending_is_a_no_op_without_a_successful_read_or_an_action_id() {
         let mut failed = file_read_observation();
         failed.status = "failed".to_string();
-        let before = failed.detail.clone();
+        let before = failed.summary.clone();
         append_agent_runtime_file_read_source_action_id(&mut failed, Some("action-1"));
-        assert_eq!(failed.detail, before);
+        assert_eq!(failed.summary, before);
 
         let mut missing = file_read_observation();
-        let before = missing.detail.clone();
+        let before = missing.summary.clone();
         append_agent_runtime_file_read_source_action_id(&mut missing, None);
-        assert_eq!(missing.detail, before);
+        assert_eq!(missing.summary, before);
 
         let mut twice = file_read_observation();
         append_agent_runtime_file_read_source_action_id(&mut twice, Some("action-1"));
-        let once = twice.detail.clone();
+        let once = twice.summary.clone();
         append_agent_runtime_file_read_source_action_id(&mut twice, Some("action-2"));
-        assert_eq!(twice.detail, once, "已经带了 id 就不再追加第二个");
+        assert_eq!(twice.summary, once, "已经带了 id 就不再追加第二个");
     }
 }