Claude OAuth token requires re-authentication after every usage limit reset #15562

Description

Describe the bug
When using Claude via OAuth (claude.ai subscription), opencode requires me to re-authenticate every time a usage limit resets. Claude.ai has two types of limits:

A 5-hour rolling limit (resets every ~5 hours)
A monthly quota

Both trigger a full re-authentication flow in opencode. This means I may need to re-login multiple times per day.
Expected behavior
OAuth tokens should be refreshed automatically using the refresh token. Re-authentication should only be required when the user explicitly logs out or when the token is truly invalidated — not on usage limit resets.
Actual behavior
After hitting either the 5-hour or monthly usage limit, opencode throws an authentication error and requires a full re-login via opencode auth login.
Why this matters
Users on Claude.ai subscription plans (Pro/Max) cannot use API keys — OAuth is their only option. Other providers do not have this issue. This is likely caused by opencode treating a 429 rate-limited or quota-exceeded response as an auth failure, and/or not properly storing/using the OAuth refresh token.
Steps to reproduce

Log in with opencode auth login using Claude OAuth
Use opencode until Claude.ai usage limit is hit (can happen within 5 hours)
Wait for the limit to reset
Try to use opencode again → re-authentication required

Environment

Provider: Claude (claude.ai OAuth)
Subscription: Claude Pro/Max (not API key)

Plugins

No response

OpenCode version

1.2.15

Steps to reproduce

No response

Screenshot and/or share link

No response

Operating System

No response

Terminal

No response