The fs-policy gate throws FS_NOT_OBSERVED when the model edits a file it
never read; that rejection surfaces as a failed tool_call_update, but no
snapshot pinned it — a regression that dropped or mis-rendered the failed
card would pass every gate. Record a scenario that edits a seeded file
without a preceding read: the edit is vetoed, the file stays unchanged on
disk, and the transcript shows the pending edit card followed by a
status:'failed' update carrying the policy error.
