Module files 

File and tar transfer. Four routes, opaque bodies, one query type.

There are no request or response bodies to model here — a file’s contents and an uncompressed tar are byte streams — so protocol::fs::FsQuery is the entire typed surface, and its failures answer text/plain rather than the JSON error body.

Two things the daemon’s contract makes non-obvious, both of which this module has to preserve rather than improve on:

• mode is octal as a string. "644" and "0644" mean the same mode, and an integer would be read as decimal 644 by anything that stringifies it.
• A missing path key is 400, and a directory where a file was asked for is 400. Only a genuinely absent path is 404. That distinction is why [file_exists] can be written at all: it keys on 404 and lets every other refusal through, so a typo in the query does not read as a missing artifact.