test: lock training workflow api contract

src/api/server.py

@@ -60,6 +60,8 @@ def route_request(
     if _is_training_progress_post(method, path):
         _validate_progress_identifier_body(body or {})
         return 404, {"error": "not_found"}
+    if _is_training_attempt_create_post(method, path):
+        _validate_attempt_create_body(body or {})
 
     deps = dependencies or build_api_dependencies()
 
@@ -254,6 +256,10 @@ def _is_training_progress_post(method: str, path: str) -> bool:
     return method == "POST" and path == "/training/progress"
 
 
+def _is_training_attempt_create_post(method: str, path: str) -> bool:
+    return method == "POST" and path == "/training/attempts"
+
+
 def _path_parts(path: str) -> list[str]:
     return [part for part in path.strip("/").split("/") if part]
 
@@ -284,6 +290,27 @@ def _validate_progress_identifier_body(body: dict) -> None:
             _parse_body_identifier(body[key], key)
 
 
+def _validate_attempt_create_body(body: dict) -> None:
+    _parse_required_json_identifier(body, "case_id")
+
+
+def _parse_required_json_identifier(body: dict, key: str) -> int:
+    if not isinstance(body, dict):
+        raise ValueError("invalid_json_body")
+    if body.get(key) is None:
+        raise ValueError(f"missing_required_json_field:{key}")
+    value = body[key]
+    if isinstance(value, bool):
+        raise ValueError(f"invalid_json_field:{key}")
+    try:
+        parsed = int(value)
+    except (TypeError, ValueError) as exc:
+        raise ValueError(f"invalid_json_field:{key}") from exc
+    if parsed < 1:
+        raise ValueError(f"invalid_json_field:{key}")
+    return parsed
+
+
 def _parse_body_identifier(value, key: str) -> int:
     if isinstance(value, bool):
         raise ValueError(f"invalid_body_field:{key}")