Dual-gate (Codex + Opus) findings on the Claude Code transcript parse cache:
1. Cache-key staleness hardening: add st_ctime_ns to the (path, mtime_ns, size,
max_messages) key so a rare same-size, same-mtime in-place edit can't serve a
stale parse. Size is already the strong discriminator for append-only JSONL;
ctime_ns is cheap defense-in-depth (a spurious bump costs one harmless re-parse,
never a stale read).
2. Timestamp-fallback bug-for-bug fix: the row-builder guard used identity
(first_ts is None and last_ts is None) but the field assignment uses truthiness
(first_ts or last_ts or _mtime). They disagreed on a falsy 0.0 timestamp
(epoch-0/1970 transcripts), leaving created_at/updated_at/last_message_at = None
instead of the file mtime the pre-cache inline code fell back to. Guard now uses
the same 'not first_ts and not last_ts' test.
Adds 3 regression tests: epoch-0 mtime fallback, the shared-dict read-only
contract (pins the load-bearing invariant), and same-size+mtime ctime invalidation.
nesquena-hermes
d61ca37bd1