[kevmo314]

The Agent issues alert recorded an authenticated Twitch /ban request on 2026-10-28 at 22:51:55 UTC: Twitch returned HTTP 400, but the agent returned HTTP 500/INTERNAL and emitted an Error Reporting event. The existing log does not retain Twitch's response message, so the exact rejection in that incident cannot be recovered.

Recognize known ban-state rejections (already banned, not banned, and protected targets) and return a callable failed-precondition with a fixed, safe message. These responses use HTTP 400 and informational request logs. Unknown 400s, missing-parameter errors, permission failures, transport errors, and 5xx responses retain error reporting. The moderation lookup also returns not-found before submitting an invalid ban/unban/timeout request when Twitch returns no matching user.

The room-readiness test keeps its fake connection open until its assertion completes, so cancellation cannot race with connection completion.

Regression tests exercise the callable protocol through the real Twitch client, verify reporting severity and response-body redaction, retain existing rate-limit behavior, and check that missing users cause no moderation request. Validation passed: CI=true TWITCH_CLI=/tmp/rtchat-twitch-cli/twitch go test -race ./..., go vet ./..., and git diff --check. The room-readiness fixture also passed 1,000 race-enabled repetitions.

Twitch documents these HTTP 400 ban-state rejections: https://dev.twitch.tv/docs/api/reference/#ban-user and https://dev.twitch.tv/docs/api/reference/#unban-user.