CLI↔server version handshake for self-hosted instances

[henry-dowling]

Clients auto-update from PyPI on every session start, but self-hosted servers only update when the operator re-pulls images — so new CLIs talking to old servers is the steady state for self-host, not an edge case.

Proposed (deferred until self-host adoption justifies it):

• Backend /health (or a /version endpoint) returns its release version.
• CLI warns when the server is more than N releases behind the client.

Prerequisite shipped in #562: servers now have a version to report at all.

🤖 Generated with Claude Code

[Keesan12]

A CLI-server handshake should do more than reject incompatible versions. It should explain which capabilities, schema, and migration path are safe so self-hosted users can recover without guessing.

Agent memory is infrastructure once teams depend on it. The version contract belongs in the execution record.

Would you negotiate capabilities or require exact version bands? I would value your take, and the open-source MartinLoop work is here if useful: https://github.com/Keesan12/martin-loop