[drewstone]

Problem. opencode reports a provider refusal as an APIError, { name: 'APIError', data: { message, statusCode, isRetryable } }. The opencode backend kept only data.message. A 429 therefore reached agent-runtime as bare prose, e.g. bridgeExecutor: bridge stream error: opencode: Rate limit reached for requests or ... opencode: Usage limit reached. Runtime reads a status field, never prose (src/runtime/supervise/upstream-unavailable.ts), so it classed the error transient and retried after about 4.5 s instead of pausing. Measured on discovery-lab run magnetar-rust-20261017c: 636 driver attempts ended this way (569 usage-limit, 67 rate-limit), each with classification: transient and a retryInMs of a few seconds. The Lab scorecard counts each one as 'a 429 killed the turn'.

Change. src/backends/opencode.ts builds a BackendFailureReason and carries data.statusCode as status when it is an integer HTTP status. It never infers a status from prose, the same rule codexFailureReason follows. The end-of-process path yields the terminal error delta instead of throwing, as codex does, so the status reaches the caller there too. agent-runtime's bridgeUpstreamError already reads error.status; a 429 maps to http-429, then unavailable, then a recorded paused row (15 s, doubling to 300 s) that spends no attempt.

Tests. tests/opencode-error-message.test.ts is deleted, not updated: it is a mock-spawner test that asserted the thrown error, and test policy deletes a mock test that breaks on a valid API change. The proof is live: the next Discovery free-seat canary must record 0 driver attempts ended by a rate or usage limit, against 636 on magnetar-rust-20261017c.

Deploy. discovery-lab's bridges (disco-bridge@8899/8900/8901) run detached checkouts at ebd7466. op-research ordered the rollout one bridge at a time, after the running RSS proof's verdict.

Run ID: run_c626287e8a8ebbf7f143ad22de478074

[tangletools]

✅ Auto-approved PR — f1be90b6

Blanket team auto-approval is intentional. This is not a code review.
No automated review runs on this PR. This approval rests on the rule above alone.

_{tangletools · auto-approval · reason: blanket_auto_approve · 2026-10-18T23:56:49Z}