Engine v0.2: flow graph, datapoint states, gates, modes, overrides, deviations (RBT-WP-0007)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Assistant: claude-code
Assistant-Model: sonnet
Assistant-Process: 295952@bnt-lap001
Assistant-Session: e93f64ad-516c-46eb-9666-aad8d300c477

rtut/v2.py

@@ -151,6 +151,11 @@ def _check_refs(m: _Model, data: dict) -> None:
             m.errs.append(f"datapoint {d['id']}: produced_by names unknown step {d['produced_by']}")
         if d.get("confirmed_by") and d["confirmed_by"] not in steps | gates:
             m.errs.append(f"datapoint {d['id']}: confirmed_by names unknown step or gate")
+    for g_id in gates:                     # a gate that requires a datapoint to be ok cannot be what confirms it
+        for ck in m.flow[g_id]["checks"]:
+            for d in ck.get("datapoints_ok", []):
+                if dps.get(d, {}).get("confirmed_by") == g_id:
+                    m.errs.append(f"gate {g_id}: checks datapoint {d} that it is itself confirmed_by (circular)")
     for a in data.get("artefacts", []):
         if a["location"]["datapoint"] not in dps:
             m.errs.append(f"artefact {a['id']}: location names unknown datapoint")