A pure async control-flow engine that executes a task across a TopologyGraph
by sequencing safe agent turns. Safety by construction: the engine can only
invoke turns via a generic TurnExecutor — it performs no side effects itself,
so §15 gating (inside each turn) is inherited and switching topology cannot
escalate authority.
- TurnExecutor trait + TurnRequest/TurnOutcome (real impl will wrap
cm-runtime::Runtime; tests use a scripted Echo executor).
- Pure planners (plan.rs): hierarchical (delegate down / synthesize up),
pipeline (topo-ordered threading), swarm (parallel attempts + aggregate).
- RunRecord journal (per-step + RunMetrics: tokens, gated actions, approvals
granted/blocked, turns) — feeds the Phase 4 comparison harness/paper.
- Unsupported kinds return an error (no panic). 5 tests, clippy clean.
Next (Phase 2b): a real TurnExecutor adapter over cm-runtime::send_message.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
