What
Before forwarding a tool call to a remote or bridged host, Claude Code pushes your local file changes and asks the peer to take them in. The barrier answers go, go with a note, or hold. On hold the call is never made and comes back as an error with code sync_failed plus an explanation of what would clear it.
Details
- Not behind a feature flag, but it short-circuits to go when the peer's Claude Code does not advertise the
sync_filesplumbing tool or the transport has no plumbing channel, so only sessions using directory sync with a new enough peer see holds.
Evidence
Not run on ${r}: ${e}, so the command would have acted on stale files. ${r} was not contacted. What clears it: ${t}.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.