# M10 SSH source evidence

The released source capability is `ssh`: private-key-only, pinned-host-key,
forced-SFTP chroot access. No password, shell, command channel, agent, default
key discovery, or arbitrary remote root is supported.

## Fixture

`tests/compose.ssh.yaml` builds a test-only OpenSSH server. Each run generates
host and client Ed25519 keys under pytest `tmp_path`, mounts no committed keys,
and configures a dedicated `backup` account with `ChrootDirectory /home/backup`
and `ForceCommand internal-sftp`. The ordinary operator Compose stack is not
modified. Run `make test-ssh-integration` to build, run, and tear down the
fixture.

## Verification

- Fake transport tests cover pin mismatch before authentication/SFTP, bounded
  reads, unsafe entries, and accepted/rejected private-key algorithms.
- The opt-in live test covers a private-key probe, backup, signed verification,
  and restore through the forced-SFTP fixture.
- `make test-ssh-integration` passed after fixture isolation and SFTP-channel
  concurrency fixes.
- Final `make check` passed: 107 unit/contract, 73 integration (one skipped),
  15 fault, and 33 security tests; Ruff, mypy, TypeScript, and the frontend
  build passed.

See `docs/runbooks/ssh-sources.md` for deployment prerequisites, rotation, and
containment limitations.