feat: certify codegen chat drafts through loop

packages/casan-harness/scripts/bash/prompt-mode-router.py

@@ -2,7 +2,8 @@
 """Plan-18 deterministic prompt mode router.
 
 MVP-0 emits READ_ONLY/BLOCK/NOT_SUPPORTED. MVP-1 adds OPERATOR only for
-registered action phrases; free commands remain NOT_SUPPORTED/BLOCK.
+registered action phrases; MVP-2 adds CODEGEN draft mode. Free commands remain
+NOT_SUPPORTED/BLOCK.
 """
 import argparse
 import json
@@ -120,23 +121,39 @@ def classify(message: str, model_verdict: str = ""):
             "classified_at": now_iso(),
         }
 
+    codegen_hits = contains_any(text, policy.get("codegen_terms", []))
+    if codegen_hits:
+        return {
+            "mode": "CODEGEN",
+            "risk": policy["codegen"]["risk"],
+            "gates": policy["codegen"]["gates"],
+            "needs_approval": bool(policy["codegen"]["needs_approval"]),
+            "reason": "codegen_draft_requested",
+            "matched_rules": codegen_hits,
+            "side_effect_allowed": False,
+            "classified_at": now_iso(),
+        }
+
     read_terms = policy.get("read_only_terms", [])
     read_hits = [t for t in read_terms if re.search(rf"\b{re.escape(t.lower())}\b", text)]
     # Model-assisted verdict can only increase caution. In MVP-0 an unsafe model
     # verdict is refused, while READ_ONLY from the model cannot override rules.
     mv = (model_verdict or "").strip().upper()
-    if mv in {"BLOCK", "NOT_SUPPORTED", "OPERATOR"}:
+    if mv in {"BLOCK", "NOT_SUPPORTED", "OPERATOR", "CODEGEN"}:
         mode = mv
-        cfg = policy["block" if mode == "BLOCK" else ("operator" if mode == "OPERATOR" else "not_supported")]
+        cfg = policy["block" if mode == "BLOCK" else ("operator" if mode == "OPERATOR" else ("codegen" if mode == "CODEGEN" else "not_supported"))]
         if mode == "OPERATOR" and not operator_hits:
             mode = "NOT_SUPPORTED"
             cfg = policy["not_supported"]
+        if mode == "CODEGEN" and not codegen_hits:
+            mode = "NOT_SUPPORTED"
+            cfg = policy["not_supported"]
         return {
             "mode": mode,
             "risk": cfg["risk"],
             "gates": cfg["gates"],
             "needs_approval": bool(cfg["needs_approval"]),
-            "reason": "model_escalated" if mode != "NOT_SUPPORTED" else "model_operator_without_registered_action",
+            "reason": "model_escalated" if mode != "NOT_SUPPORTED" else "model_requested_unsupported_action",
             "matched_rules": [f"model:{mode}"],
             "side_effect_allowed": mode == "OPERATOR",
             "classified_at": now_iso(),