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coder/coderd/externalauth
J. Scott Miller 3da8226876 fix(coderd/externalauth): support disabling token refresh retries (#26231)
`TestRefreshToken/RefreshRetries` flakes on Windows. The subtest
disables transient-failure refresh retries by setting
`RefreshRetryTimeout = time.Nanosecond`, but a near-zero timeout cannot
deterministically prevent a retry: on coarse-clock platforms the 1ns
deadline may not register as expired until after the first refresh
attempt completes, and `retry.Wait`'s first delay is zero, so an extra
IDP refresh attempt slips through and the attempt-count assertion fails
with `refreshCount = totalRefreshes + 1`.

A negative `RefreshRetryTimeout` now disables transient-failure retries
explicitly so exactly one refresh attempt is made, and the test sets
`-1` instead of `time.Nanosecond`. The retry config fields are only set
from tests, so default refresh behavior is unchanged.

Closes https://github.com/coder/internal/issues/1550 (PLAT-293)

<details>
<summary>Root cause analysis</summary>

1. The test sets `RefreshRetryTimeout = time.Nanosecond` intending "no
retries".
2. `refreshTokenWithRetry` creates `context.WithTimeout(ctx, 1ns)`. On
Linux this context is canceled synchronously at creation: consecutive
`time.Now()` reads differ by more than 1ns, so `context.WithDeadline`
observes `time.Until(deadline) <= 0`. The `retryCtx.Err() != nil` guard
then deterministically stops after one attempt.
3. On Windows, `time.Now()` is coarse, so both clock reads inside
`WithTimeout` can return the same instant, and a real 1ns timer is
scheduled instead of synchronous cancellation.
4. The fake IDP is served in-process, so the first refresh attempt can
complete before that timer fires. `retryCtx.Err()` is still nil and
`retry.Wait`'s first delay is zero, so a second refresh attempt happens.
5. `require.Equal(t, refreshCount, totalRefreshes)` then fails with
`expected: 2, actual: 1` (or `4 vs 3` when the race hits a later loop
iteration), matching all CI occurrences.

Timing-based test-side mitigations cannot close this race, so the fix
adds explicit retry-disable semantics instead. `RefreshRetries` passed
100 consecutive local runs with the change.

</details>

*This PR was generated by Coder Agents on behalf of @jscottmiller.*
2026-06-11 15:33:20 -05:00
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