fix(server): Prevent error message on stream abort (complete fix)

Root Cause Analysis:
When user presses ESC to abort streaming, the AI SDK throws NoOutputGeneratedError
which propagates through TWO error handlers:
1. ai-orchestrator.ts: Stream error events (case "error")
2. stream-orchestrator.ts: Outer catch block for execution errors

Previously, both handlers unconditionally emitted error events, causing
"No output generated" to appear in UI on intentional abort.

Complete Fix:

1. ai-orchestrator.ts (lines 400-422):
   - Stream error events now check if error contains "No output generated"
   - Abort errors → set state.aborted, call onAbort() (no error emitted)
   - Real errors → add error part, emit error event

2. stream-orchestrator.ts (lines 564-571):
   - Outer catch block now checks errorMessage and state.aborted
   - Abort errors → skip emitError(), only complete observer
   - Real errors → emit error event normally

Architecture:
- Two-layer error detection prevents abort errors at both levels
- state.aborted provides additional signal for abort detection
- Error message pattern matching catches AI SDK abort errors
- Real errors still emit properly for debugging

Result: ESC abort now cleanly stops without error message or hanging.

Author: shtse8

packages/code-server/src/services/streaming/ai-orchestrator.ts

@@ -398,14 +398,26 @@ export async function processAIStream(
 				}
 
 				case "error": {
-					state.currentStepParts.push({
-						type: "error",
-						error: String(chunk.error),
-						status: "completed",
-					});
-					hasError = true;
-					emitError(observer, String(chunk.error));
-					callbacks.onError?.(String(chunk.error));
+					// Check if this is an abort-related error (NoOutputGeneratedError)
+					// These errors are expected when user cancels stream via ESC key
+					const errorStr = String(chunk.error);
+					const isAbortError = errorStr.includes("No output generated") || state.aborted;
+
+					if (isAbortError) {
+						// Treat as abort, not error
+						state.aborted = true;
+						callbacks.onAbort?.();
+					} else {
+						// Real error - add to parts and emit
+						state.currentStepParts.push({
+							type: "error",
+							error: errorStr,
+							status: "completed",
+						});
+						hasError = true;
+						emitError(observer, errorStr);
+						callbacks.onError?.(errorStr);
+					}
 					break;
 				}
 

packages/code-server/src/services/streaming/stream-orchestrator.ts

@@ -560,7 +560,26 @@ export function streamAIResponse(opts: StreamAIResponseOptions): Observable<Stre
 					console.error("[StreamOrchestrator] Error keys:", Object.keys(error));
 					console.error("[StreamOrchestrator] Error JSON:", JSON.stringify(error, null, 2));
 				}
-				emitError(observer, error instanceof Error ? error.message : String(error));
+
+				// Check if this is an abort error (NoOutputGeneratedError or intentional abort)
+				const errorMessage = error instanceof Error ? error.message : String(error);
+				const isAbortError = errorMessage.includes("No output generated") || state.aborted;
+
+				if (isAbortError) {
+					// For abort errors: update message status to trigger cleanup, but don't emit error event
+					await updateMessageStatus(
+						assistantMessageId,
+						"abort",
+						undefined, // no finishReason
+						undefined, // no usage
+						messageRepository,
+						observer,
+					);
+				} else {
+					// Real error: emit error event for debugging
+					emitError(observer, errorMessage);
+				}
+
 				observer.complete();
 			}
 		})();