[bug]: Copilot Business over-limit usage falls back to plan-only

[vmvarela]

Pre-flight checks

• I searched existing issues and did not find a duplicate request.
• I verified this on the current production OpenCode release.

OpenCode version tested

2.0.20

opencode-quota version tested

5.0.0

Bug summary

For GitHub Copilot Business on token-based billing, usage beyond the included AI-credit allowance is displayed as plan-only, even though GitHub reports the used credit count and a 0% remaining percentage.

Steps to reproduce

1. Sign in to GitHub Copilot Business from OpenCode.
2. Exceed the included AI-credit entitlement for the current billing cycle.
3. Check the quota sidebar or /quota_status.

The GitHub Copilot internal user response for the affected account reports token_based_billing: true and a premium_interactions snapshot with entitlement: 3000, quota_remaining: -739.5, remaining: -740, credits_used: 3739, percent_remaining: 0, and has_quota: false. The GitHub UI shows 3,739 / 3,000 AI credits and says usage is paused until reset.

Expected behavior

Show the reported usage and remaining percentage, e.g. 3,739/3,000 and 0% left, with the reset time.

Actual behavior

The live probe succeeds, but the entry is Plan: business | quota details unavailable; the over-limit usage amount and percentage are omitted.

Relevant logs/output

copilot_quota_auth:
- billing_model: ai_credits
- quota_api: copilot_internal_user
- oauth_configured: true
- effective_source: oauth
- live_probe: success
- live_entry_1: Plan: value=business | quota details unavailable reset_at=2026-10-01T00:00:00.000Z

The snapshot has a negative remaining value after the allowance is exceeded. This is distinct from #57, which addressed displaying percentages above 100%, and #126, which added general Copilot AI Credit support.

[llucax]

Thanks for the quick fix in #301! Would you consider putting it in a 4.10.x release too? 5.x is OpenCode 2 only, and on OpenCode 1 (1.18.33 here) with 4.10.6 I hit exactly this today: a Copilot Business seat over its AI credits shows "quota details unavailable" instead of 0% left. The copilot_internal/user response has the same shape as the one in this issue (quota_remaining -102.8, remaining -103, credits_used 7203 of entitlement 7100, percent_remaining 0, has_quota false), and the new block in parseCopilotInternalUser() looks like it would apply to 4.10.6 as is. Totally fine if 4.x is frozen now, just asking.

[slkiser]

@llucax I've backported this fix to the 4.x line for OpenCode 1. It will ship in v4.10.7, which @slkiser/opencode-quota@4 picks up automatically once it's published.