Stop retrying unrecoverable native sessions

[laotoutou]

Summary

• terminalize a native Session after three consecutive same-epoch codex_native_session_unrecoverable responses
• atomically clear stale active/pending control state and mark the product Session failed
• preserve retries for transport and other transient failures so normal long-running work is unaffected
• document the terminal reconciliation path and its compare-and-swap protections

Root cause

An unreadable Codex rollout caused every thread/read reconciliation to return codex_native_session_unrecoverable. Sandpi treated that explicit permanent failure like a transient error forever, leaving active/pending state set and preventing the Environment idle-pause guard from succeeding.

Validation

• npm test — 703 passed
• npm run lint
• npm run typecheck
• npm run openapi:check
• npm run build