Summary

Closes: #20

Changes

Adds crates/cpex-hosts-python — a new Rust crate that lets the Rust PluginManager host Python plugins via subprocess isolation, rather than requiring a Python host process.

Key pieces:

• cpex-hosts-python crate — drives Python plugin classes over the same JSON-lines stdin/stdout protocol that worker.py uses. Manages venv creation/caching, subprocess lifecycle, and hook dispatch from Rust.
• IsolatedPythonPluginAdapter — a Plugin + AnyHookHandler impl that wraps one Python class in a dedicated worker subprocess.
• VenvManager — creates and caches per-plugin virtual environments from a requirements.txt.
• WorkerProcess — manages the worker.py subprocess lifecycle (spawn, send, recv, restart on failure).
• Python-side fixes (cpex/framework/base.py, isolated/worker.py):
  • HookRef now resolves namespaced hooks like cmf.tool_pre_invoke by falling back to the bare name tool_pre_invoke, so convention-named plugin methods work with CMF-namespaced hooks.
  • worker.py normalizes namespaced hook names the same way, and preserves request_id in unexpected error responses.

Checks

• make lint passes
• make test passes
• CHANGELOG updated (if user-facing)