fix(codex): trust zero-credit usage response

[robinebers]

Summary

• Trust Codex credits.balance from the usage response body when credits data is present.
• Preserve the credits header as a fallback for responses without body credits.
• Add a regression test for accounts with has_credits: false and balance: "0".

Fixes #465

Test plan

• bunx vitest run plugins/codex/plugin.test.js

Made with Cursor

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Note

Low Risk
Low risk: small, localized change to how the Codex plugin derives remaining credits, plus a regression test to lock in behavior for zero-credit accounts.

Overview
Fixes Codex credit reporting to trust credits in the usage response body when present (including correctly treating has_credits: false / balance: "0" as zero), while keeping the x-codex-credits-balance header as a fallback when body credits are missing.

Adds a regression test covering the no-credits account case where the header reports a non-zero balance but the response body indicates zero credits.

^{Reviewed by Cursor Bugbot for commit efa6f36. Bugbot is set up for automated code reviews on this repo. Configure here.}

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Summary by cubic

Fixes Codex credit parsing to trust the usage response body when present, so zero-credit accounts show correct usage. Keeps the header as a fallback to avoid regressions.

• Bug Fixes
  • Read credits.balance from the body when available; if has_credits: false, treat as 0.
  • Fallback to x-codex-credits-balance header when body credits are missing.
  • Add a regression test for has_credits: false with balance: "0".

^{Written for commit efa6f36. Summary will update on new commits. Review in cubic}

[cubic-dev-ai]

No issues found across 2 files

_{Re-trigger cubic}