A degenerate tool name stored in conversation history (dots, spaces,
unicode from an earlier model degeneration) bricks every subsequent
Codex Responses turn with a non-retryable HTTP 400:
Invalid input[N].name: string does not match pattern '^[a-zA-Z0-9_-]+'
The 400 replays forever until the user manually starts a new session.
Add _sanitize_replayed_fn_name() — replaces invalid chars with '_'
(runs collapsed), degrades all-invalid names to 'fn' instead of empty
(an empty name would trade one 400 for a preflight ValueError). Applied
at both replay sites: the chat-message converter and the preflight
choke-point. Live tool-definition names are left untouched — they must
match the dispatch registry exactly. Pairing is by call_id, so
renaming a replayed function_call is safe.
call_id overflow (the sibling half of #49224) was already fixed on main
by #73492 (_clamp_responses_call_id); this commit covers the remaining
invalid-name defect.
Credit: @Morad37 (#31678 — identified the bug, the replay sites, and
the regex contract), @lubosxyz (#49224 — replace-not-strip semantics
and 'fn' fallback to avoid the empty-name trap).
Fixes#31666
kshitijk4poor
31485d50ea