Add the orchestrator infrastructure for replacing the Rust execution
loop with versioned Python code. This commit adds the module and host
functions without switching over — the existing Rust loop is unchanged.
New files:
- orchestrator/default.py: v0 Python orchestrator (run_loop + helpers)
- executor/orchestrator.rs: host function dispatch, orchestrator
loading from Store with version selection, OrchestratorResult parsing
Host functions exposed to orchestrator Python via Monty suspension:
__llm_complete__, __execute_code_step__ (nested Monty VM),
__execute_action__, __check_signals__, __emit_event__,
__add_message__, __save_checkpoint__, __transition_to__,
__retrieve_docs__, __check_budget__, __get_actions__
Also makes json_to_monty, monty_to_json, monty_to_string pub(crate)
in scripting.rs for cross-module use.
Design doc: docs/plans/2026-03-25-python-orchestrator.md
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
