diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/codex_app_server/mod.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/codex_app_server/mod.rs
index 3cb7bc305..83c7de9f9 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/codex_app_server/mod.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/codex_app_server/mod.rs
@@ -1060,38 +1060,46 @@ fn should_emit_direct_codex_activity(
     true
 }
 
+/// 思考正文增量事件：`item/reasoning/summaryTextDelta`（reasoning item 的 `summary`）与
+/// `item/reasoning/textDelta`（它的 `content`）都下发正文，不降级成"preparing 活动文本"。
+///
+/// 这里只是把"完成时才看到"提前为"边生成边看到"：两段文本本来就随 `item/completed`
+/// 落进 `project.jsonl` 并展示给用户，可见范围没有放宽；未识别的 plan 文本与命令输出
+/// 仍然只降级为活动状态。运行态读取器和 `direct_codex_notification_event` 共用这一处，
+/// 避免两份实现再次分叉（分叉时就出现过"生产路径从不产生 ReasoningDelta"）。
+fn direct_codex_reasoning_delta_event(
+    method: &str,
+    params: &serde_json::Value,
+) -> Option<CodexTurnEvent> {
+    if !matches!(
+        method,
+        "item/reasoning/summaryTextDelta" | "item/reasoning/textDelta"
+    ) {
+        return None;
+    }
+    params
+        .get("delta")
+        .and_then(serde_json::Value::as_str)
+        .filter(|value| !value.is_empty())
+        .map(|delta| CodexTurnEvent::ReasoningDelta {
+            item_id: params
+                .get("itemId")
+                .and_then(serde_json::Value::as_str)
+                .filter(|value| !value.is_empty())
+                .map(str::to_string)
+                .unwrap_or_else(|| "direct-missing-item".to_string()),
+            delta: delta.to_string(),
+        })
+}
+
 fn direct_codex_notification_event(
     method: &str,
     params: &serde_json::Value,
     intermediate_text: Option<String>,
     safe_activity: Option<&'static str>,
 ) -> Option<CodexTurnEvent> {
-    // 思考正文走独立通道，交给 DirectProject 的运行态事件；它不因为
-    // "preparing 活动" 的降级规则被丢掉，否则界面只能等 item/completed 才看到思考。
-    //
-    // 两条通知都下发正文，不下发活动文本：
-    // - `item/reasoning/summaryTextDelta`（core `ReasoningContentDelta`）→ reasoning item 的 `summary`；
-    // - `item/reasoning/textDelta`（core `ReasoningRawContentDelta`）→ reasoning item 的 `content`，
-    //   正是 `project.jsonl` 里保存、并在此前 `item/completed` 已经展示给用户的同一段文本。
-    // 因此这里只是把"完成时才看到"提前为"边生成边看到"，没有放宽可见文本的范围；
-    // 未识别的 plan 文本与命令输出仍然只降级为活动状态，不下发正文。
-    if matches!(
-        method,
-        "item/reasoning/summaryTextDelta" | "item/reasoning/textDelta"
-    ) {
-        return params
-            .get("delta")
-            .and_then(serde_json::Value::as_str)
-            .filter(|value| !value.is_empty())
-            .map(|delta| CodexTurnEvent::ReasoningDelta {
-                item_id: params
-                    .get("itemId")
-                    .and_then(serde_json::Value::as_str)
-                    .filter(|value| !value.is_empty())
-                    .map(str::to_string)
-                    .unwrap_or_else(|| "direct-missing-item".to_string()),
-                delta: delta.to_string(),
-            });
+    if let Some(event) = direct_codex_reasoning_delta_event(method, params) {
+        return Some(event);
     }
     let (activity, intermediate_text) = match (&intermediate_text, safe_activity) {
         (Some(_), Some(activity)) if activity == "preparing" => (Some(activity), None),
@@ -3988,12 +3996,18 @@ async fn read_game_creator_codex_app_server_stdout(
         let Some(turn_id) = turn_id else {
             continue;
         };
-        if let Some(activity) = safe_activity {
-            let last_activity = last_direct_activity_by_turn
-                .entry(turn_id.clone())
-                .or_default();
-            if !should_emit_direct_codex_activity(last_activity, activity) {
-                continue;
+        // 思考正文走正文通道，不参与 `preparing` 活动的降级与节流：活动节流按类别抑制
+        // 连续的 preparing，逐段思考正文会被整段吃掉——这正是生产路径此前从不产生
+        // `ReasoningDelta` 的原因。正文仍沿用下面的正文节流，避免重复 chunk 反复入队。
+        let reasoning_delta = direct_codex_reasoning_delta_event(method, &params);
+        if reasoning_delta.is_none() {
+            if let Some(activity) = safe_activity {
+                let last_activity = last_direct_activity_by_turn
+                    .entry(turn_id.clone())
+                    .or_default();
+                if !should_emit_direct_codex_activity(last_activity, activity) {
+                    continue;
+                }
             }
         }
         if let Some(text) = intermediate_text.as_deref() {
@@ -4004,7 +4018,9 @@ async fn read_game_creator_codex_app_server_stdout(
                 continue;
             }
         }
-        let event = if let Some(kind) = direct_codex_resolution_event_type(method) {
+        let event = if let Some(event) = reasoning_delta {
+            event
+        } else if let Some(kind) = direct_codex_resolution_event_type(method) {
             CodexTurnEvent::Request { kind, params }
         } else if let Some(activity) = safe_activity {
             // Preparing notifications may carry private plan/reasoning text;
@@ -4783,18 +4799,49 @@ mod tests {
         );
     }
 
+    /// 判据：思考正文走 `ReasoningDelta` 正文通道（与 ADR 一致），不再被 `preparing`
+    /// 活动降级吃掉；plan 文本与命令输出仍然只降级成活动类别，不带正文。
     #[test]
-    fn direct_preparing_notifications_emit_thinking_activity_without_raw_text() {
-        let reasoning = serde_json::json!({ "delta": "hidden reasoning must not leak" });
-        assert!(matches!(
-            direct_codex_notification_event(
+    fn direct_reasoning_deltas_stream_text_while_plan_and_command_output_stay_activity() {
+        let reasoning = serde_json::json!({ "itemId": "reasoning-1", "delta": "思考正文" });
+        for method in [
+            "item/reasoning/summaryTextDelta",
+            "item/reasoning/textDelta",
+        ] {
+            assert!(
+                matches!(
+                    direct_codex_reasoning_delta_event(method, &reasoning),
+                    Some(CodexTurnEvent::ReasoningDelta { item_id, delta })
+                        if item_id == "reasoning-1" && delta == "思考正文"
+                ),
+                "{method} 必须下发明文思考增量"
+            );
+            // 运行态读取器用的就是这一个分类函数，不能再走「preparing 活动」降级。
+            assert!(
+                matches!(
+                    direct_codex_notification_event(
+                        method,
+                        &reasoning,
+                        Some("思考正文".to_string()),
+                        Some("preparing"),
+                    ),
+                    Some(CodexTurnEvent::ReasoningDelta { .. })
+                ),
+                "{method} 在通知分类里不能降级成活动"
+            );
+        }
+        assert!(
+            direct_codex_reasoning_delta_event(
                 "item/reasoning/textDelta",
-                &reasoning,
-                Some("hidden reasoning must not leak".to_string()),
-                Some("preparing"),
-            ),
-            Some(CodexTurnEvent::Activity("preparing"))
-        ));
+                &serde_json::json!({ "delta": "" }),
+            )
+            .is_none(),
+            "空增量不产生正文事件"
+        );
+        assert!(
+            direct_codex_reasoning_delta_event("turn/plan/updated", &reasoning).is_none(),
+            "非 reasoning 通知不进正文通道"
+        );
 
         let plan = serde_json::json!({ "explanation": "private plan text must not leak" });
         assert!(matches!(
@@ -6288,6 +6335,79 @@ while IFS= read -r line; do :; done
         assert_eq!(connection.inner.threads.lock().await.len(), 1);
     }
 
+    /// 判据：生产读取器不再把思考正文降级成 `preparing` 活动。
+    ///
+    /// fixture 刻意不发 `turn/started` 等先导活动，所以"活动节流"这条退路不存在：
+    /// 一旦读取器把 `item/reasoning/*Delta` 归回活动通道，observations 里就会出现
+    /// `Activity("preparing")`。同时明文思考只走 DirectProject 正文通道，
+    /// 不得漏进旧的运行态 observation。
+    #[cfg(unix)]
+    #[tokio::test]
+    async fn codex_app_server_streams_reasoning_deltas_without_activity_fallback() {
+        use std::os::unix::fs::PermissionsExt;
+
+        let temp = tempfile::tempdir().expect("temp dir");
+        let executable = temp.path().join("fake-codex-app-server-reasoning-delta");
+        std::fs::write(
+            &executable,
+            r#"#!/bin/sh
+IFS= read -r initialize
+case "$initialize" in *'"method":"initialize"'*) ;; *) exit 51 ;; esac
+printf '%s\n' '{"id":1,"result":{"codexHome":"/tmp","platformFamily":"unix","platformOs":"linux","userAgent":"fixture"}}'
+IFS= read -r initialized
+case "$initialized" in *'"method":"initialized"'*) ;; *) exit 52 ;; esac
+IFS= read -r thread_start
+case "$thread_start" in *'"method":"thread/start"'*) ;; *) exit 53 ;; esac
+printf '%s\n' '{"id":2,"result":{"thread":{"id":"thread-1"}}}'
+IFS= read -r turn_start
+case "$turn_start" in *'"method":"turn/start"'*) ;; *) exit 54 ;; esac
+printf '%s\n' '{"id":3,"result":{"turn":{"id":"turn-1","items":[],"status":"inProgress"}}}'
+printf '%s\n' '{"method":"item/reasoning/textDelta","params":{"threadId":"thread-1","turnId":"turn-1","itemId":"reasoning-1","delta":"SECRET_REASONING_TEXT"}}'
+printf '%s\n' '{"method":"item/agentMessage/delta","params":{"threadId":"thread-1","turnId":"turn-1","itemId":"item-1","delta":"{\"toolCalls\":[]}"}}'
+printf '%s\n' '{"method":"item/completed","params":{"completedAtMs":1,"threadId":"thread-1","turnId":"turn-1","item":{"id":"item-1","type":"agentMessage","text":"{\"toolCalls\":[]}"}}}'
+printf '%s\n' '{"method":"turn/completed","params":{"threadId":"thread-1","turn":{"id":"turn-1","items":[],"status":"completed"}}}'
+while IFS= read -r line; do :; done
+"#,
+        )
+        .expect("write fake app-server");
+        let mut permissions = std::fs::metadata(&executable)
+            .expect("fake metadata")
+            .permissions();
+        permissions.set_mode(0o700);
+        std::fs::set_permissions(&executable, permissions).expect("chmod fake app-server");
+
+        let llm = test_llm();
+        let connection =
+            CodexAppServerConnection::spawn_with_executable(&llm, executable.as_os_str())
+                .await
+                .expect("spawn fake app-server");
+        let mut observations = Vec::new();
+        let mut observer = |observation| observations.push(observation);
+        connection
+            .run_turn_with_direct_observer(
+                &test_snapshot(),
+                &llm,
+                tool_request(),
+                None,
+                Some(&mut observer),
+                None,
+            )
+            .await
+            .expect("run fake app-server turn");
+        drop(observer);
+        assert!(
+            !observations.iter().any(|observation| matches!(
+                observation,
+                DirectCodexTurnObservation::Activity("preparing")
+            )),
+            "思考增量必须走 ReasoningDelta 正文通道，不能降级成 preparing 活动"
+        );
+        assert!(
+            !format!("{observations:?}").contains("SECRET_REASONING_TEXT"),
+            "明文思考不得漏进运行态 observation"
+        );
+    }
+
     #[cfg(unix)]
     #[tokio::test]
     async fn direct_home_app_server_uses_read_only_protocol_and_rejects_file_change_items() {