[codex] MCP OAuth: concurrent processes race refresh-token rotation in .credentials.json; next startup hits invalid_grant and demands re-login

## Observed symptom MCP OAuth: concurrent processes race refresh-token rotation in .credentials.json; next startup hits invalid_grant and demands re-login What version of Codex CLI is running? `codex-cli 0.157.1` (npm), Linux x86_64, KDE/Wayland. Home on persistent ext4. `mcp_oauth_credentials_store = "file"`. ## Literal error text ``` WARN codex_rmcp_client::oauth::refresh_transaction|MCP OAuth refresh token was rejected; reauthorization required error=OAuth refresh token was rejected: Server returned error response: invalid_grant: Invalid refresh token ``` ## Environment GitHub openai/codex #48507 ## Trigger / context Public GitHub report in openai/codex (FRESH_7D). ## Source evidence - https://github.com/openai/codex/issues/48507 (2026-09-28T21:43:51Z) — evidence_class: PRIMARY_ISSUE_REPORT — #48507 ## Freshness - classification: FRESH_7D - retrieved_at: 2026-10-02T10:10:25.435874Z - scout_id: C64f23d030d ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.