BUG: "Too Many Requests: Rate limit exceeded" error appears excessively frequently #596

Summary

The session surfaces "Too Many Requests: Rate limit exceeded / retrying in 1s - attempt #2"
very frequently during normal use. The user expects this message to appear rarely or not at
all; instead it fires repeatedly and intrudes on the workflow.

Context

• Extension: harmoniqs.amicode 0.3.0 (darwin-arm64)
• Engine pin: v1.18.10-amicode.17 (upstream base v1.18.10), repo harmoniqs/opencode
• OS: Darwin 25.6.0 arm64
• No active run at time of report.

Expected vs actual

Expected: Rate-limit retries are infrequent or invisible; normal sessions proceed without
interruption.
Actual: The "Too Many Requests: Rate limit exceeded / retrying in 1s - attempt #2" message
surfaces very frequently during a session, indicating the retry loop fires far more often
than expected.

intake: not-ready — mature per the maturity contract before picking up
suggested_path: B
diagnostics: pointer-only
upstream: anomalyco/opencode#30510 (open) — "Rate limit retries every ~1 second with no backoff or max limit"; anomalyco/opencode#33955 (open) — "Zen gateway loses provider retry timing and retries 429s early"