diff --git a/circuitforge_core/community/models.py b/circuitforge_core/community/models.py
index 7f115f3..45c2eb7 100644
--- a/circuitforge_core/community/models.py
+++ b/circuitforge_core/community/models.py
@@ -66,29 +66,25 @@ class CommunityPost:
     protein_pct: float | None
     moisture_pct: float | None
 
-    def __new__(cls, **kwargs):
-        # Convert lists to tuples before frozen dataclass assignment
-        for key in ("slots", "dietary_tags", "allergen_flags", "flavor_molecules"):
-            if key in kwargs and isinstance(kwargs[key], list):
-                kwargs[key] = tuple(kwargs[key])
-        return object.__new__(cls)
-
     def __init__(self, **kwargs):
-        # Convert lists to tuples
+        # 1. Coerce list fields to tuples
         for key in ("slots", "dietary_tags", "allergen_flags", "flavor_molecules"):
             if key in kwargs and isinstance(kwargs[key], list):
                 kwargs[key] = tuple(kwargs[key])
-        for f in self.__dataclass_fields__:
-            object.__setattr__(self, f, kwargs[f])
-        self.__post_init__()
 
-    def __post_init__(self) -> None:
-        if self.post_type not in _VALID_POST_TYPES:
+        # 2. Validate BEFORE assignment
+        post_type = kwargs.get("post_type")
+        if post_type not in _VALID_POST_TYPES:
             raise ValueError(
-                f"post_type must be one of {sorted(_VALID_POST_TYPES)}, got {self.post_type!r}"
+                f"post_type must be one of {sorted(_VALID_POST_TYPES)}, got {post_type!r}"
             )
         for score_name in (
             "seasoning_score", "richness_score", "brightness_score",
             "depth_score", "aroma_score", "structure_score",
         ):
-            _validate_score(score_name, getattr(self, score_name))
+            if score_name in kwargs:
+                _validate_score(score_name, kwargs[score_name])
+
+        # 3. Assign all fields
+        for f in self.__dataclass_fields__:
+            object.__setattr__(self, f, kwargs[f])