Codex login can leave the current auth fingerprint marked as already synchronized even after the matching saved snapshot file is removed or pruned. The sync fast path now verifies the session snapshot still exists before skipping, and use resolves exact email requests to the saved duplicate snapshot when the canonical filename is absent.

Constraint: Operators use official codex login as the primary auth source

Rejected: Only improving the not-found message | leaves the refresh-required loop and missing snapshot unrepaired

Confidence: high

Scope-risk: narrow

Directive: Do not skip external auth sync solely from fingerprint unless the mapped snapshot file still exists

Tested: npm test -- --runInBand

Tested: npm pack --dry-run

Not-tested: live codex login against real OpenAI account

Co-authored-by: NagyVikt <nagy.viktordp@gmail.com>

Co-authored-by: OmX <omx@oh-my-codex.dev>