diff --git a/src/cleveragents/core/validation.py b/src/cleveragents/core/validation.py
index f03ee5044..d24ce63cd 100644
--- a/src/cleveragents/core/validation.py
+++ b/src/cleveragents/core/validation.py
@@ -56,7 +56,7 @@ DECISION_CLI_REQUIRED_FIELDS: dict[str, type | tuple[type, ...] | None] = {
     "sequence": int,             # sequence_number
     "question": str,             # question text
     "chosen": str,               # chosen_option text
-    "confidence": (float, None), # ge=0.0, le=1.0 or None
+    "confidence": (float, type(None)), # ge=0.0, le=1.0 or None
     "parent": str,               # parent ULID or "(root)"
     "is_correction": bool,       # True / False
     "superseded": bool,          # True / False
@@ -151,8 +151,13 @@ def validate_plan_tree(nodes: list[dict[str, Any]]) -> dict[str, Any]:
 
         # --- type ---
         node_type = node.get("type")
-        if node_type is not None and (not isinstance(node_type, str) or not node_type.strip()):
-            errors.append(f"node[{idx}] 'type' must be a non-empty string")
+        if (
+            node_type is not None
+            and (not isinstance(node_type, str) or not node_type.strip())
+        ):
+            errors.append(
+                f"node[{idx}] 'type' must be a non-empty string"
+            )
             valid = False
 
         # --- sequence ---
@@ -160,7 +165,8 @@ def validate_plan_tree(nodes: list[dict[str, Any]]) -> dict[str, Any]:
         if seq is not None:
             if not isinstance(seq, int) or isinstance(seq, bool) or seq < 0:
                 errors.append(
-                    f"node[{idx}] 'sequence' must be a non-negative integer, got {seq!r}"
+                    f"node[{idx}] 'sequence' must be a non-negative "
+                    f"integer, got {seq!r}"
                 )
                 valid = False
             else:
@@ -178,8 +184,13 @@ def validate_plan_tree(nodes: list[dict[str, Any]]) -> dict[str, Any]:
 
         # --- question ---
         question = node.get("question")
-        if question is not None and (not isinstance(question, str) or not question.strip()):
-            errors.append(f"node[{idx}] 'question' must be a non-empty string")
+        if (
+            question is not None
+            and (not isinstance(question, str) or not question.strip())
+        ):
+            errors.append(
+                f"node[{idx}] 'question' must be a non-empty string"
+            )
             valid = False
 
         # --- children ---
@@ -236,7 +247,7 @@ def validate_decision_dict(d: dict[str, Any]) -> dict[str, Any]:
     warnings: list[str] = []
     valid = True
 
-    for field, expected in DECISION_CLI_REQUIRED_FIELDS.items():
+    for field in DECISION_CLI_REQUIRED_FIELDS:
         if field not in d:
             errors.append(f"missing required field: {field}")
             valid = False
@@ -294,12 +305,11 @@ def validate_decision_dict(d: dict[str, Any]) -> dict[str, Any]:
                 valid = False
 
         # --- sequence (int) ---
-        elif field == "sequence":
-            if not isinstance(value, int) or isinstance(value, bool):
-                errors.append(
-                    f"'{field}' must be an integer, got {type(value).__name__}"
-                )
-                valid = False
+        elif not (isinstance(value, int) and not isinstance(value, bool)):
+            errors.append(
+                f"'{field}' must be an integer, got {type(value).__name__}"
+            )
+            valid = False
 
     return {
         "valid": valid,
@@ -476,8 +486,8 @@ def validate_structured_component_output(
 __all__ = [
     "DECISION_CLI_REQUIRED_FIELDS",
     "PLAN_TREE_REQUIRED_KEYS",
-    "VALID_STATUSES",
     "ULID_PATTERN",
+    "VALID_STATUSES",
     "ValidationError",
     "ValidationWarning",
     "validate_decision_dict",