diff --git a/src-tauri/src/claude_desktop_config.rs b/src-tauri/src/claude_desktop_config.rs
index 4f51c65ff..d629db2eb 100644
--- a/src-tauri/src/claude_desktop_config.rs
+++ b/src-tauri/src/claude_desktop_config.rs
@@ -378,6 +378,9 @@ fn inference_model_json(spec: &InferenceModelSpec) -> Value {
         }
         if spec.supports_1m {
             item["supports1m"] = json!(true);
+            // 只有 `supports1m` 时 Desktop 每个模型列两行（原名 + 「1M context window」）。
+            // 加上 `prefer1m`（1.21459.0 起）只列原名，交给内嵌 CLI 时自动补 `[1m]`。
+            item["prefer1m"] = json!(true);
         }
         item
     } else {
@@ -1844,7 +1847,7 @@ mod tests {
         );
         assert_eq!(
             profile["inferenceModels"],
-            json!([{ "name": "claude-sonnet-4-6", "supports1m": true }])
+            json!([{ "name": "claude-sonnet-4-6", "supports1m": true, "prefer1m": true }])
         );
     }
 
@@ -1887,7 +1890,7 @@ mod tests {
             .starts_with("ccs-"));
         assert_eq!(
             profile["inferenceModels"],
-            json!([{ "name": "claude-sonnet-4-6", "labelOverride": "Kimi K2", "supports1m": true }])
+            json!([{ "name": "claude-sonnet-4-6", "labelOverride": "Kimi K2", "supports1m": true, "prefer1m": true }])
         );
         assert!(!profile.to_string().contains("kimi-k2"));
     }
diff --git a/src-tauri/src/mode/stack.rs b/src-tauri/src/mode/stack.rs
index aa758e60b..1f128048d 100644
--- a/src-tauri/src/mode/stack.rs
+++ b/src-tauri/src/mode/stack.rs
@@ -114,7 +114,7 @@ fn slug(text: &str) -> String {
 }
 
 /// Stack 模型 id。Claude 的上游是 1M 窗口时末尾带 `[1M]`，Claude Code 才按 1M 计算；Claude
-/// Desktop 的 1M 写在模型条目里（`supports1m`），id 不带标记。
+/// Desktop 的 1M 写在模型条目里（`supports1m` + `prefer1m`），id 不带标记。
 pub fn encode(app: &AppType, key: &str, model: &str, one_m: bool) -> String {
     match app {
         AppType::Codex => format!("{CODEX_PREFIX}{key}{CODEX_SEPARATOR}{model}"),
@@ -182,7 +182,7 @@ pub fn decode<'a>(app: &AppType, id: &'a str) -> Decoded<'a> {
             let Some(rest) = id.strip_prefix(DESKTOP_PREFIX) else {
                 return Decoded::Plain;
             };
-            // Desktop 给 `supports1m` 的条目多生成一行 `<id>[1m]`
+            // 1M 条目 Desktop 发请求时用 `<id>[1m]`（`prefer1m` 自动补；旧版另列一行）
             let code = strip_one_m_suffix_for_upstream(rest);
             return if code.len() == DESKTOP_CODE_DIGITS && code.bytes().all(|b| b.is_ascii_digit())
             {
diff --git a/src-tauri/src/services/provider/mod.rs b/src-tauri/src/services/provider/mod.rs
index f680b9058..b87159a11 100644
--- a/src-tauri/src/services/provider/mod.rs
+++ b/src-tauri/src/services/provider/mod.rs
@@ -2382,7 +2382,7 @@ requires_openai_auth = true
         assert_eq!(profile["inferenceGatewayAuthScheme"], json!("bearer"));
         assert_eq!(
             profile["inferenceModels"],
-            json!([{ "name": "claude-sonnet-4-6", "labelOverride": "DeepSeek V4 Flash Updated", "supports1m": true }]),
+            json!([{ "name": "claude-sonnet-4-6", "labelOverride": "DeepSeek V4 Flash Updated", "supports1m": true, "prefer1m": true }]),
             "provider edits should propagate into the Claude Desktop 3P profile during takeover"
         );
     }