Cleanup and fix transient error detection in review

packages/engine/src/transient-error-detector.test.ts

@@ -86,6 +86,17 @@ describe("Transient Error Detector", () => {
       expect(isTransientError("Error: request was aborted")).toBe(true);
     });
 
+    it("matches 'operation was aborted' (DOMException-style abort errors)", () => {
+      expect(isTransientError("operation was aborted")).toBe(true);
+      expect(isTransientError("This operation was aborted")).toBe(true);
+      expect(isTransientError("OPERATION WAS ABORTED")).toBe(true);
+    });
+
+    it("does NOT match user-initiated 'operation was aborted by user'", () => {
+      expect(isTransientError("The operation was aborted by user")).toBe(false);
+      expect(isTransientError("operation was aborted by the signal")).toBe(false);
+    });
+
     // Edge cases
     it("returns false for empty string", () => {
       expect(isTransientError("")).toBe(false);

packages/engine/src/transient-error-detector.ts

@@ -52,6 +52,10 @@ export const TRANSIENT_ERROR_PATTERNS: RegExp[] = [
   // AI provider abort errors — temporary request cancellations (e.g., Anthropic streaming aborts)
   // These occur when the provider's infrastructure drops an in-flight request.
   /request was aborted/i,
+  // DOMException-style AbortError ("This operation was aborted"), emitted by fetch/
+  // AbortController when a provider drops an in-flight operation. Excludes user-
+  // initiated cancellations like "operation was aborted by user" — those are not transient.
+  /operation was aborted(?!\s+by\b)/i,
 ];
 
 /**
@@ -91,6 +95,7 @@ export function isTransientError(errorMessage: string): boolean {
  */
 const SILENT_TRANSIENT_PATTERNS: RegExp[] = [
   /request was aborted/i,
+  /operation was aborted(?!\s+by\b)/i,
 ];
 
 /**