fix(agents): treat provider request-aborted as timeout for fallback (#1576)

* fix(agents): treat request-aborted as timeout for fallback

* test(e2e): add provider timeout fallback

src/agents/failover-error.ts

@@ -1,6 +1,7 @@
 import { classifyFailoverReason, type FailoverReason } from "./pi-embedded-helpers.js";
 
 const TIMEOUT_HINT_RE = /timeout|timed out|deadline exceeded|context deadline exceeded/i;
+const ABORT_TIMEOUT_RE = /request was aborted|request aborted/i;
 
 export class FailoverError extends Error {
   readonly reason: FailoverReason;
@@ -104,6 +105,8 @@ export function isTimeoutError(err: unknown): boolean {
   if (hasTimeoutHint(err)) return true;
   if (!err || typeof err !== "object") return false;
   if (getErrorName(err) !== "AbortError") return false;
+  const message = getErrorMessage(err);
+  if (message && ABORT_TIMEOUT_RE.test(message)) return true;
   const cause = "cause" in err ? (err as { cause?: unknown }).cause : undefined;
   const reason = "reason" in err ? (err as { reason?: unknown }).reason : undefined;
   return hasTimeoutHint(cause) || hasTimeoutHint(reason);

src/agents/model-fallback.test.ts

@@ -346,6 +346,28 @@ describe("runWithModelFallback", () => {
     expect(run.mock.calls[1]?.[1]).toBe("claude-haiku-3-5");
   });
 
+  it("falls back on provider abort errors with request-aborted messages", async () => {
+    const cfg = makeCfg();
+    const run = vi
+      .fn()
+      .mockRejectedValueOnce(
+        Object.assign(new Error("Request was aborted"), { name: "AbortError" }),
+      )
+      .mockResolvedValueOnce("ok");
+
+    const result = await runWithModelFallback({
+      cfg,
+      provider: "openai",
+      model: "gpt-4.1-mini",
+      run,
+    });
+
+    expect(result.result).toBe("ok");
+    expect(run).toHaveBeenCalledTimes(2);
+    expect(run.mock.calls[1]?.[0]).toBe("anthropic");
+    expect(run.mock.calls[1]?.[1]).toBe("claude-haiku-3-5");
+  });
+
   it("does not fall back on user aborts", async () => {
     const cfg = makeCfg();
     const run = vi