Codex/Opus gate finding: in eager session-save mode the current user turn is
checkpointed into s.messages before the agent runs (no id yet); after
_assign_stable_message_ids stamps the returned result row, the display merge
keeps the durable eager checkpoint and skips the stamped result — leaving the
display row id-less while its context twin carries the minted id, silently
defeating id-based fork/truncate alignment for eager-mode users. The merge now
copies the minted id onto the kept checkpoint when it lacks one (guarded so it
can't overwrite or duplicate). Opus verified cross-array id pairing holds across
the real 3-turn transform pipeline.
nesquena-hermes
a8568749a1