fix(compute): preserve waitUntil rejection semantics (#83)

Author: rtbenfield

packages/compute/src/scale-to-zero.ts

@@ -139,9 +139,13 @@ export function waitUntil(
 ): void {
   const guard = new ScaleToZeroGuard(options);
 
-  void Promise.resolve(promise)
-    .finally(() => {
+  // Do not attach a catch here; callers rely on the underlying promise keeping
+  // its normal unhandled-rejection behavior.
+  void Promise.resolve(promise).finally(() => {
+    try {
       guard.release();
-    })
-    .catch(() => {});
+    } catch {
+      // Guard cleanup must not replace the application promise's result.
+    }
+  });
 }

packages/compute/tests/scale-to-zero.test.ts

@@ -83,17 +83,6 @@ describe("scale-to-zero guard", () => {
     expect(await readSignals(file)).toBe("+-");
   });
 
-  it("waitUntil releases after the promise rejects", async () => {
-    const { file } = await createControlFile();
-    const promise = Promise.reject(new Error("background failed"));
-
-    expect(waitUntil(promise)).toBeUndefined();
-    await expect(promise).rejects.toThrow("background failed");
-    await Promise.resolve();
-
-    expect(await readSignals(file)).toBe("+-");
-  });
-
   it("waitUntil signal abort releases before a still-pending promise settles", async () => {
     const { file } = await createControlFile();
     const controller = new AbortController();