Task flow engine implementation

api/routers/capability_requests.py

@@ -7,6 +7,7 @@ from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from api.database import get_session
+from api.flow_defs import assertion_result_to_dict, evaluate_transition, flow_result_to_dict
 from api.models.agent_message import AgentMessage
 from api.models.capability_catalog import CapabilityCatalog
 from api.models.capability_request import CapabilityRequest
@@ -28,22 +29,6 @@ from api.schemas.capability_request import (
 
 router = APIRouter(tags=["capability-requests"])
 
-# ---------------------------------------------------------------------------
-# Lifecycle guard
-# ---------------------------------------------------------------------------
-
-_VALID_TRANSITIONS: dict[str, set[str]] = {
-    "requested":         {"accepted", "rejected", "withdrawn", "routing_disputed"},
-    "routing_disputed":  {"requested", "withdrawn"},
-    "accepted":          {"in_progress", "rejected", "withdrawn"},
-    "in_progress":       {"ready_for_review", "rejected", "withdrawn"},
-    "ready_for_review":  {"completed", "in_progress", "withdrawn"},
-    "completed":         set(),
-    "rejected":          set(),
-    "withdrawn":         set(),
-}
-
-
 # ---------------------------------------------------------------------------
 # Capability Catalog endpoints
 # ---------------------------------------------------------------------------
@@ -602,12 +587,21 @@ async def _get_request_or_404(request_id: uuid.UUID, session: AsyncSession) -> C
 
 
 def _check_transition(current: str, target: str) -> None:
-    allowed = _VALID_TRANSITIONS.get(current, set())
-    if target not in allowed:
+    can_reach, failures, flow_result = evaluate_transition(
+        "capability_request",
+        current,
+        target,
+    )
+    if not can_reach:
         raise HTTPException(
             status_code=422,
-            detail=(
-                f"Cannot transition from '{current}' to '{target}'. "
-                f"Allowed: {sorted(allowed) or 'none (terminal state)'}"
-            ),
+            detail={
+                "message": f"Cannot transition from '{current}' to '{target}'.",
+                "current_workstation": current,
+                "target_workstation": target,
+                "blocking_assertions": [
+                    assertion_result_to_dict(item) for item in failures
+                ],
+                "flow_result": flow_result_to_dict(flow_result),
+            },
         )