fix(opencode): cap retry backoff when response headers lack retry-after - #33733

Issue for this PR

Closes #33728

Type of change

• Bug fix
• New feature
• Refactor / code improvement
• Documentation

What does this PR do?

SessionRetry.delay() in packages/opencode/src/session/retry.ts only applied the 30-second RETRY_MAX_DELAY_NO_HEADERS cap in the no-headers branch (line 65). When a retryable error carried any responseHeaders object — which real 502/503 responses almost always do, since they always send content-type, date, etc. — but the headers did not include a parseable retry-after / retry-after-ms, the fallback path used uncapped exponential backoff bounded only by RETRY_MAX_DELAY (2,147,483,647 ms, the setTimeout limit).

That meant a single flaky 5xx could grow the backoff to ~17 min by attempt 10, ~9 hours by attempt 15, and ~12 days by attempt 20. The 30 s cap was effectively dead in production because real responses always carry headers.

The fix applies the same Math.min(..., RETRY_MAX_DELAY_NO_HEADERS) to the headers-branch fallback that the no-headers branch already uses. One-line change.

How did you verify your code works?

• Added two regression tests in packages/opencode/test/session/retry.test.ts:
  • caps delay at 30 seconds when headers present but lack retry-after — runs 10 attempts with { "content-type": "application/json" } and asserts the same [2000, 4000, 8000, 16000, 30000, 30000, 30000, 30000, 30000, 30000] shape the no-headers test already expects.
  • caps delay at 30 seconds when retry-after header is unparseable — delay(8, ...) with { "retry-after": "not-a-number" } returns 30000 (was returning 256000 before the fix).
• Confirmed both new tests fail without the source fix and pass with it.
• bun test test/session/retry.test.ts from packages/opencode → 35 pass / 0 fail.
• bun run typecheck from packages/opencode → clean.

Screenshots / recordings

N/A — no UI changes.

Checklist

• I have tested my changes locally
• I have not included unrelated changes in this PR