flake: TestProxy_HotReloadRouting (multiple variants, Windows EOF)

This issue tracks intermittent Windows EOF failures from routed HTTPS requests in the enterprise/aibridgeproxyd hot-reload test family. The routing decision succeeds, but the loopback proxy-to-aibridged round trip returns no response; goproxy closes the MITM connection and the test client surfaces EOF.

Original occurrence:

CI Run: https://github.com/coder/coder/actions/runs/26933139214
Job: https://github.com/coder/coder/actions/runs/26933139214/job/79456825080
Commit: becc858fa85182ed55a45d1a317bc7e60da8f8bb (author: Ethan)

Failure:

=== FAIL: enterprise/aibridgeproxyd TestProxy_HotReloadRoutingInvalidProviders/RefreshErrorPreservesPreviousSnapshot
    reload_test.go:574:
        Error: Received unexpected error:
        Post "https://alpha.invalid/v1/messages": EOF
        Messages: request to routed host must succeed

Error analysis:

• The proxy routed request to aibridged returned EOF during the "refresh error preserves previous snapshot" assertion.
• The test expects the previous router snapshot to continue serving requests after a reload error; the EOF suggests a transient proxy/MITM connection failure.

Root cause classification: flaky test / Windows loopback infrastructure pressure.

Race/Panic/OOM evidence: none found in the original logs.

Assignment analysis:

• git log --oneline -10 --follow enterprise/aibridgeproxyd/reload_test.go
  • 12520ee964 "feat: add ai provider status and reload freshness metrics" (Danny Kopping)
  • a9f5ed7644 "fix: re-validate provider per request and classify reloads" (Danny Kopping)
  • 79e007cf30 "feat: hot-reload aibridged and aibridgeproxyd providers on DB changes" (Danny Kopping; introduced this test file and CRUD test)

Assigned to Danny based on test/component ownership, not the failing commit author.

Reproduction:

• go test ./enterprise/aibridgeproxyd -run 'TestProxy_HotReloadRouting' -count=100
• The original occurrence could not be reproduced on Linux after 5,000+ iterations; the observed failures are on Windows under full-suite loopback connection churn.