[abruption]

Summary

Closes #16.

Rolling out 0.3.0 meant running install.sh against four machines by hand, from memory, with nothing to say which were stale. That is exactly the case where being behind matters most — a messaging tool's whole job is the fleet.

$ cc-peer list --host build-server
build-server runs cc-peer 0.2.0; this machine has 0.3.0.
Update it with:  cc-peer update --host build-server

NAME         PID   STATUS  CWD
api-worker   4011  idle    /srv/api

$ cc-peer update --check
cc-peer 0.3.0 — up to date

A mistake worth recording

The first draft read the version out of the run_remote() response. That looks right and is wrong: run_remote ships this file and runs it over there, so the reply always echoes our own version. It surfaced when a host I had deliberately put on 0.4.0-test reported 0.3.0.

The fix asks the machine what it has installed, over SSH, at the path install.sh uses — the copy a session over there will actually run, and the only one that can fall behind. That probe validates its ssh arguments too, since it builds its own command (#6).

Design notes

• update stages and renames. We are running from the file being replaced, so it writes cc_peer.py.new alongside and moves it into place; a failed download can't leave half a script behind. Permissions are carried over.
• update --host reports, it does not make the target fetch. Hosts with no route to GitHub are one of the reasons this tool exists, and install.sh --host already pushes over the SSH connection itself. Making the far side reach out would break the air-gapped case the README advertises.
• A missing or too-old remote install says so plainly rather than looking like a version match.

Type

• feat
• fix
• docs
• chore / refactor / test / perf

Checklist

• python3 cc_peer.py list works locally
• python3 cc_peer.py list --host <a real host> works over SSH
• --dry-run resolves a target without posting anything
• Commits follow Conventional Commits
• Docs updated if behavior changed (README / SKILL.md / CLAUDE.md)
• No secrets, tokens, or session keys in the diff

Verified against

v2.1.263 — 41/41 tests passing (7 new). Mismatch detection exercised for real by installing 0.4.0-test on the KR host, confirming the warning, then restoring 0.3.0. Backwards compatible: a remote without the probe path reports nothing rather than failing.