OpenClaw uses strict host-key checking for SCP, so the relay host key must already exist in `~/.ssh/known_hosts`.

Attachment paths are validated against allowed roots (`attachmentRoots` / `remoteAttachmentRoots`).

<Warning>

Any `cliPath` wrapper or SSH proxy you put in front of `imsg` MUST behave like a transparent stdio pipe for long-lived JSON-RPC. OpenClaw exchanges small newline-framed JSON-RPC messages over the wrapper's stdin/stdout for the lifetime of the channel:

- Forward each stdin chunk/line **as soon as bytes are available** — don't wait for EOF.

- Forward each stdout chunk/line promptly in the reverse direction.

- Preserve newlines.

- Avoid fixed-size blocking reads (`read(4096)`, `cat | buffer`, default shell `read`) that can starve small frames.

- Keep stderr separate from the JSON-RPC stdout stream.

A wrapper that buffers stdin until a large block fills will produce symptoms that look like an iMessage outage — `imsg rpc timeout (chats.list)` or repeated channel restarts — even though `imsg rpc` itself is healthy. `ssh -T host imsg "$@"` (above) is safe because it forwards OpenClaw's `cliPath` arguments such as `rpc` and `--db`. Pipelines like `ssh host imsg | grep -v '^DEBUG'` are NOT — line-buffered tools can still hold frames; use `stdbuf -oL -eL` on every stage if you must filter.

</Warning>

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