diff --git a/sgl-router/src/routers/grpc/responses/conversions.rs b/sgl-router/src/routers/grpc/responses/conversions.rs
index 431e02ea6..b55b8c1ca 100644
--- a/sgl-router/src/routers/grpc/responses/conversions.rs
+++ b/sgl-router/src/routers/grpc/responses/conversions.rs
@@ -187,7 +187,7 @@ fn extract_text_from_content(content: &[ResponseContentPart]) -> String {
 /// Convert a ChatCompletionResponse to ResponsesResponse
 ///
 /// # Conversion Logic
-/// - `id` → `id` (pass through)
+/// - `id` → `response_id_override` if provided, otherwise `chat_resp.id`
 /// - `model` → `model` (pass through)
 /// - `choices[0].message` → `output` array (convert to ResponseOutputItem::Message)
 /// - `choices[0].finish_reason` → determines `status` (stop/length → Completed)
@@ -195,6 +195,7 @@ fn extract_text_from_content(content: &[ResponseContentPart]) -> String {
 pub fn chat_to_responses(
     chat_resp: &ChatCompletionResponse,
     original_req: &ResponsesRequest,
+    response_id_override: Option<String>,
 ) -> Result<ResponsesResponse, String> {
     // Extract the first choice (responses API doesn't support n>1)
     let choice = chat_resp
@@ -275,7 +276,7 @@ pub fn chat_to_responses(
 
     // Generate response
     Ok(ResponsesResponse {
-        id: chat_resp.id.clone(),
+        id: response_id_override.unwrap_or_else(|| chat_resp.id.clone()),
         object: "response".to_string(),
         created_at: chat_resp.created as i64,
         status,
diff --git a/sgl-router/src/routers/grpc/responses/handlers.rs b/sgl-router/src/routers/grpc/responses/handlers.rs
index 3c2d774ee..89309df44 100644
--- a/sgl-router/src/routers/grpc/responses/handlers.rs
+++ b/sgl-router/src/routers/grpc/responses/handlers.rs
@@ -21,7 +21,7 @@ use futures_util::StreamExt;
 use serde_json::json;
 use tokio::sync::{mpsc, RwLock};
 use tokio_stream::wrappers::UnboundedReceiverStream;
-use tracing::{debug, warn};
+use tracing::{debug, error, warn};
 use uuid::Uuid;
 
 use super::{
@@ -935,14 +935,14 @@ async fn execute_without_mcp(
             headers,
             model_id,
             components,
-            response_id,
+            response_id.clone(),
             background_tasks,
         )
         .await
         .map_err(|e| format!("Pipeline execution failed: {}", e))?;
 
     // Convert ChatCompletionResponse → ResponsesResponse
-    conversions::chat_to_responses(&chat_response, original_request)
+    conversions::chat_to_responses(&chat_response, original_request, response_id)
         .map_err(|e| format!("Failed to convert to responses format: {}", e))
 }
 
@@ -1207,13 +1207,20 @@ pub async fn cancel_response_impl(
                         )
                             .into_response()
                     } else {
-                        // Task handle not found (may have already completed)
+                        // Task handle not found but status is queued/in_progress
+                        // This can happen if: (1) task crashed, or (2) storage persistence failed
+                        error!(
+                            "Response {} has status '{}' but task handle is missing. Task may have crashed or storage update failed.",
+                            response_id, current_status
+                        );
                         (
-                            StatusCode::OK,
+                            StatusCode::INTERNAL_SERVER_ERROR,
                             axum::Json(json!({
-                                "id": response_id,
-                                "status": "completed_or_not_found",
-                                "message": "Task may have already completed before cancellation"
+                                "error": {
+                                    "message": "Internal error: background task completed but failed to update status in storage",
+                                    "type": "internal_error",
+                                    "code": "status_update_failed"
+                                }
                             })),
                         )
                             .into_response()
diff --git a/sgl-router/src/routers/grpc/responses/tool_loop.rs b/sgl-router/src/routers/grpc/responses/tool_loop.rs
index e81bad118..2c0dfe109 100644
--- a/sgl-router/src/routers/grpc/responses/tool_loop.rs
+++ b/sgl-router/src/routers/grpc/responses/tool_loop.rs
@@ -365,9 +365,12 @@ pub(super) async fn execute_tool_loop(
                 );
 
                 // Convert chat response to responses format and mark as incomplete
-                let mut responses_response =
-                    conversions::chat_to_responses(&chat_response, original_request)
-                        .map_err(|e| format!("Failed to convert to responses format: {}", e))?;
+                let mut responses_response = conversions::chat_to_responses(
+                    &chat_response,
+                    original_request,
+                    response_id.clone(),
+                )
+                .map_err(|e| format!("Failed to convert to responses format: {}", e))?;
 
                 // Mark as completed but with incomplete details
                 responses_response.status = ResponseStatus::Completed;
@@ -461,9 +464,12 @@ pub(super) async fn execute_tool_loop(
             );
 
             // Convert final chat response to responses format
-            let mut responses_response =
-                conversions::chat_to_responses(&chat_response, original_request)
-                    .map_err(|e| format!("Failed to convert to responses format: {}", e))?;
+            let mut responses_response = conversions::chat_to_responses(
+                &chat_response,
+                original_request,
+                response_id.clone(),
+            )
+            .map_err(|e| format!("Failed to convert to responses format: {}", e))?;
 
             // Inject MCP metadata into output
             if state.total_calls > 0 {