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[v2] e2e `protocol:timeout:max-total` is flaky over SSE: fake timers advance before the request reaches the server

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Evaluación

Dificultad
2/5
Tiempo estimado
1-3 horas
Aptitud para principiantes
72/100
Tipo de issue
Error
Claridad
Bastante claro
Estado de actividad
Activo
Stack tecnológico
typescript
Área
testing-qa

Línea de trabajo

Empieza con las variantes de SSE de protocol:timeout:max-total en test/e2e/scenarios/protocol.test.ts y compara sus pasos con temporizadores falsos con el patrón vi.waitFor del test timeout:reset-on-progress. Ejecuta el comando de reproducción del issue, incluidas ejecuciones repetidas, para confirmar el fallo intermitente. Se considera terminado cuando el test alcanza de forma fiable los eventos de progreso del servidor y SSE informa Maximum total timeout exceeded como los otros transportes.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

v1 v2
What happened?

On macOS, the two SSE variants of protocol:timeout:max-total in test/e2e/scenarios/protocol.test.ts fail intermittently on a clean clone of main. The other transports always pass, and CI on main is green.

AssertionError: expected 0 to be greater than or equal to 3
 ❯ scenarios/protocol.test.ts:713:30

followed by an unhandled SdkError: Request timed out.

The failure rate moves around. On Oct 14 it failed in the full suite and in 3 of 3 isolated runs. On Oct 16, -t "timeout:basic|timeout:max-total" failed 3 of 6 times, while the max-total test on its own passed 6 of 6.

What I think is happening: the test switches to fake timers, starts the call, and immediately advances the clock in 200ms steps. Over SSE, the tools/call request is a real HTTP POST, and the fake clock doesn't wait for it. When the POST is slow to land, the clock is already past the 500ms per-request timeout, so the call rejects with Request timed out before the server sends any progress. In those runs the test never reaches maxTotalTimeout at all.

To check, I added temporary logging of server-sent progress, client-received progress, and each clock step. In failing runs, the server's first progress shows up only after the clock reaches 600ms, by which point the call has already been rejected. Then I added 10ms of real time (a setTimeout captured before useFakeTimers) after each advanceTimersByTimeAsync. With that, all 12 variants passed on 3 of 3 runs, and SSE rejects with Maximum total timeout exceeded after 4 progress ticks, the same as the other transports.

The sleep only confirms the cause; it isn't a fix. protocol:timeout:reset-on-progress already avoids this race by awaiting vi.waitFor(() => expect(received.length).toBeGreaterThanOrEqual(i)) after each step, and max-total has no equivalent. Waiting until the server has received the call before advancing the clock should fix it. One wrinkle: vi.waitFor advances fake timers while it polls, so the wait needs to sit where it can't eat into the timeout budget under test.

Happy to open a test-only PR if that approach sounds right.

What did you expect?

The test passes regardless of machine speed, and actually exercises maxTotalTimeout over SSE.

Code to reproduce
cd test/e2e
pnpm vitest run scenarios/protocol.test.ts -t "timeout:basic|timeout:max-total"
# intermittent, so run it several times
SDK version

main @ 9bc40e90 (macOS / Darwin 27, Node 24.16.0, pnpm 10.26.1)

Area

Transports

Lenguaje dominante
TypeScript
Estrellas
13.6k
Forks
2.3k
Merge medio
1 d 2 h
PR fusionados (30 d)
51

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