[Feature Request / Bug] Handle Rate Limit (Quota Exceeded 429) automatically with retry delay

Description

Description: When using Gemini API models (e.g., gemini-3.8-flash) on the free tier, hitting rate limits results in a hard failure instead of automatic waiting/retrying based on the suggested backoff time.

Error Message:

You exceeded your current quota, please check your plan and billing details. For more information on this error, head to: https://ai.google.dev/gemini-api/docs/rate-limits. To monitor your current usage, head to: https://ai.dev/rate-limit.

• Quota exceeded for metric: generativelanguage.googleapis.com/generate_content_free_tier_requests, limit: 20, model: gemini-3.8-flash
  Please retry in 38.601658672s.

Proposed Solution: Implement automatic retry logic (exponential backoff or waiting for the exact seconds specified in the error message like Please retry in X seconds) when encountering API quota/rate-limit errors.

Plugins

No response

OpenCode version

1.18.31

Steps to reproduce

Ask any question requiring a sequence of 5–10 processing steps using the latest Gemini LLM via the Gemini API.

Screenshot and/or share link

No response

Operating System

fedora 44

Terminal

No response