Codex assigns assistant message items server-side ids that can run
400+ chars (base64 encrypted blobs), but the Responses API caps
input[].id at 64 chars and rejects the whole request with a
non-retryable HTTP 400. Once a session captures one of these long
ids, every subsequent turn replays it and 400s forever, since the
history persists it in codex_message_items.
Add a 64-char length guard at both replay sites — the history-to-
input converter and the final preflight gate — so oversized ids are
dropped while short ids (msg_...) are kept for prefix-cache hits.
Mirrors the existing pattern for reasoning items, which already
strip their id before replay because store=False means the API
can't resolve ids server-side anyway.
Fixes#27038
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
joaomarcos
0b2907f586