fix: resolve SQLite embedding ValueError by using TypeDecorator (fixes #382)

The SQLite models inherited embedding: list[float] from parent classes
but never overrode it with an SQLAlchemy-compatible column type. When
SQLModel tried to create table columns, list had no matching SQLAlchemy
type, raising ValueError.

Replace the embedding_json + property pattern with a JSONEncodedList
TypeDecorator that maps list[float] to TEXT via JSON serialization,
matching how PostgreSQL models use Column(Vector()) to override the
parent field.

Author: octo-patch

src/memu/database/sqlite/models.py

@@ -11,13 +11,39 @@
 import pendulum
 from pydantic import BaseModel
 from sqlalchemy import JSON, MetaData, String, Text
+from sqlalchemy.types import TypeDecorator
 from sqlmodel import Column, DateTime, Field, Index, SQLModel, func
 
 from memu.database.models import CategoryItem, MemoryCategory, MemoryItem, MemoryType, Resource
 
 logger = logging.getLogger(__name__)
 
 
+class JSONEncodedList(TypeDecorator):
+    """Store a list of floats as a JSON-encoded TEXT column.
+
+    SQLite has no native vector type, so embeddings are serialized to JSON
+    strings for storage and deserialized back to ``list[float]`` on read.
+    """
+
+    impl = Text
+    cache_ok = True
+
+    def process_bind_param(self, value: list[float] | None, dialect: Any) -> str | None:
+        if value is not None:
+            return json.dumps(value)
+        return None
+
+    def process_result_value(self, value: str | None, dialect: Any) -> list[float] | None:
+        if value is not None:
+            try:
+                return [float(x) for x in json.loads(value)]
+            except (json.JSONDecodeError, TypeError, ValueError):
+                logger.warning("Failed to decode embedding JSON from SQLite")
+                return None
+        return None
+
+
 class TZDateTime(DateTime):
     """DateTime type with timezone support."""
 
@@ -52,27 +78,7 @@ class SQLiteResourceModel(SQLiteBaseModelMixin, Resource):
     modality: str = Field(sa_column=Column(String, nullable=False))
     local_path: str = Field(sa_column=Column(String, nullable=False))
     caption: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-    # Store embedding as JSON string since SQLite doesn't have native vector type
-    embedding_json: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
-
-    @property
-    def embedding(self) -> list[float] | None:
-        """Parse embedding from JSON string."""
-        if self.embedding_json is None:
-            return None
-        try:
-            return list(json.loads(self.embedding_json))
-        except (json.JSONDecodeError, TypeError) as e:
-            logger.warning("Failed to parse resource embedding JSON: %s", e)
-            return None
-
-    @embedding.setter
-    def embedding(self, value: list[float] | None) -> None:
-        """Serialize embedding to JSON string."""
-        if value is None:
-            self.embedding_json = None
-        else:
-            self.embedding_json = json.dumps(value)
+    embedding: list[float] | None = Field(default=None, sa_column=Column(JSONEncodedList(), nullable=True))
 
 
 class SQLiteMemoryItemModel(SQLiteBaseModelMixin, MemoryItem):
@@ -81,59 +87,19 @@ class SQLiteMemoryItemModel(SQLiteBaseModelMixin, MemoryItem):
     resource_id: str | None = Field(sa_column=Column(String, nullable=True))
     memory_type: MemoryType = Field(sa_column=Column(String, nullable=False))
     summary: str = Field(sa_column=Column(Text, nullable=False))
-    # Store embedding as JSON string since SQLite doesn't have native vector type
-    embedding_json: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    embedding: list[float] | None = Field(default=None, sa_column=Column(JSONEncodedList(), nullable=True))
     happened_at: datetime | None = Field(default=None, sa_column=Column(DateTime, nullable=True))
     extra: dict[str, Any] = Field(default={}, sa_column=Column(JSON, nullable=True))
 
-    @property
-    def embedding(self) -> list[float] | None:
-        """Parse embedding from JSON string."""
-        if self.embedding_json is None:
-            return None
-        try:
-            return list(json.loads(self.embedding_json))
-        except (json.JSONDecodeError, TypeError) as e:
-            logger.warning("Failed to parse memory item embedding JSON: %s", e)
-            return None
-
-    @embedding.setter
-    def embedding(self, value: list[float] | None) -> None:
-        """Serialize embedding to JSON string."""
-        if value is None:
-            self.embedding_json = None
-        else:
-            self.embedding_json = json.dumps(value)
-
 
 class SQLiteMemoryCategoryModel(SQLiteBaseModelMixin, MemoryCategory):
     """SQLite memory category model."""
 
     name: str = Field(sa_column=Column(String, nullable=False, index=True))
     description: str = Field(sa_column=Column(Text, nullable=False))
-    # Store embedding as JSON string since SQLite doesn't have native vector type
-    embedding_json: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
+    embedding: list[float] | None = Field(default=None, sa_column=Column(JSONEncodedList(), nullable=True))
     summary: str | None = Field(default=None, sa_column=Column(Text, nullable=True))
 
-    @property
-    def embedding(self) -> list[float] | None:
-        """Parse embedding from JSON string."""
-        if self.embedding_json is None:
-            return None
-        try:
-            return list(json.loads(self.embedding_json))
-        except (json.JSONDecodeError, TypeError) as e:
-            logger.warning("Failed to parse category embedding JSON: %s", e)
-            return None
-
-    @embedding.setter
-    def embedding(self, value: list[float] | None) -> None:
-        """Serialize embedding to JSON string."""
-        if value is None:
-            self.embedding_json = None
-        else:
-            self.embedding_json = json.dumps(value)
-
 
 class SQLiteCategoryItemModel(SQLiteBaseModelMixin, CategoryItem):
     """SQLite category-item relation model."""

src/memu/database/sqlite/repositories/memory_category_repo.py

@@ -70,7 +70,7 @@ def list_categories(self, where: Mapping[str, Any] | None = None) -> dict[str, M
                 id=row.id,
                 name=row.name,
                 description=row.description,
-                embedding=self._normalize_embedding(row.embedding_json),
+                embedding=row.embedding,
                 summary=row.summary,
                 created_at=row.created_at,
                 updated_at=row.updated_at,
@@ -104,7 +104,7 @@ def clear_categories(self, where: Mapping[str, Any] | None = None) -> dict[str,
                     id=row.id,
                     name=row.name,
                     description=row.description,
-                    embedding=self._normalize_embedding(row.embedding_json),
+                    embedding=row.embedding,
                     summary=row.summary,
                     created_at=row.created_at,
                     updated_at=row.updated_at,
@@ -156,7 +156,7 @@ def get_or_create_category(
                     id=existing.id,
                     name=existing.name,
                     description=existing.description,
-                    embedding=self._normalize_embedding(existing.embedding_json),
+                    embedding=existing.embedding,
                     summary=existing.summary,
                     created_at=existing.created_at,
                     updated_at=existing.updated_at,
@@ -170,7 +170,7 @@ def get_or_create_category(
             row = self._memory_category_model(
                 name=name,
                 description=description,
-                embedding_json=self._prepare_embedding(embedding),
+                embedding=embedding,
                 summary=None,
                 created_at=now,
                 updated_at=now,
@@ -230,7 +230,7 @@ def update_category(
             if description is not None:
                 row.description = description
             if embedding is not None:
-                row.embedding_json = self._prepare_embedding(embedding)
+                row.embedding = embedding
             if summary is not None:
                 row.summary = summary
             row.updated_at = self._now()
@@ -243,7 +243,7 @@ def update_category(
             id=row.id,
             name=row.name,
             description=row.description,
-            embedding=self._normalize_embedding(row.embedding_json),
+            embedding=row.embedding,
             summary=row.summary,
             created_at=row.created_at,
             updated_at=row.updated_at,

src/memu/database/sqlite/repositories/memory_item_repo.py

@@ -75,7 +75,7 @@ def get_item(self, item_id: str) -> MemoryItem | None:
             resource_id=row.resource_id,
             memory_type=row.memory_type,
             summary=row.summary,
-            embedding=self._normalize_embedding(row.embedding_json),
+            embedding=row.embedding,
             created_at=row.created_at,
             updated_at=row.updated_at,
             **self._scope_kwargs_from(row),
@@ -106,7 +106,7 @@ def list_items(self, where: Mapping[str, Any] | None = None) -> dict[str, Memory
                 resource_id=row.resource_id,
                 memory_type=row.memory_type,
                 summary=row.summary,
-                embedding=self._normalize_embedding(row.embedding_json),
+                embedding=row.embedding,
                 created_at=row.created_at,
                 updated_at=row.updated_at,
                 **self._scope_kwargs_from(row),
@@ -151,7 +151,7 @@ def list_items_by_ref_ids(
                 resource_id=row.resource_id,
                 memory_type=row.memory_type,
                 summary=row.summary,
-                embedding=self._normalize_embedding(row.embedding_json),
+                embedding=row.embedding,
                 created_at=row.created_at,
                 updated_at=row.updated_at,
                 **self._scope_kwargs_from(row),
@@ -185,7 +185,7 @@ def clear_items(self, where: Mapping[str, Any] | None = None) -> dict[str, Memor
                     resource_id=row.resource_id,
                     memory_type=row.memory_type,
                     summary=row.summary,
-                    embedding=self._normalize_embedding(row.embedding_json),
+                    embedding=row.embedding,
                     created_at=row.created_at,
                     updated_at=row.updated_at,
                     **self._scope_kwargs_from(row),
@@ -257,7 +257,7 @@ def create_item(
             resource_id=resource_id,
             memory_type=memory_type,
             summary=summary,
-            embedding_json=self._prepare_embedding(embedding),
+            embedding=embedding,
             extra=extra if extra else {},
             created_at=now,
             updated_at=now,
@@ -338,7 +338,7 @@ def create_item_reinforce(
                     resource_id=existing.resource_id,
                     memory_type=existing.memory_type,
                     summary=existing.summary,
-                    embedding=self._normalize_embedding(existing.embedding_json),
+                    embedding=existing.embedding,
                     created_at=existing.created_at,
                     updated_at=existing.updated_at,
                     extra=existing.extra,
@@ -360,7 +360,7 @@ def create_item_reinforce(
                 resource_id=resource_id,
                 memory_type=memory_type,
                 summary=summary,
-                embedding_json=self._prepare_embedding(embedding),
+                embedding=embedding,
                 extra=item_extra,
                 created_at=now,
                 updated_at=now,
@@ -424,7 +424,7 @@ def update_item(
             if summary is not None:
                 row.summary = summary
             if embedding is not None:
-                row.embedding_json = self._prepare_embedding(embedding)
+                row.embedding = embedding
 
             # Merge extra and tool_record into existing extra dict
             current_extra = row.extra or {}
@@ -449,7 +449,7 @@ def update_item(
             resource_id=row.resource_id,
             memory_type=row.memory_type,
             summary=row.summary,
-            embedding=self._normalize_embedding(row.embedding_json),
+            embedding=row.embedding,
             extra=row.extra,
             created_at=row.created_at,
             updated_at=row.updated_at,

src/memu/database/sqlite/repositories/resource_repo.py

@@ -76,7 +76,7 @@ def list_resources(self, where: Mapping[str, Any] | None = None) -> dict[str, Re
                 modality=row.modality,
                 local_path=row.local_path,
                 caption=row.caption,
-                embedding=self._normalize_embedding(row.embedding_json),
+                embedding=row.embedding,
                 created_at=row.created_at,
                 updated_at=row.updated_at,
                 **self._scope_kwargs_from(row),
@@ -111,7 +111,7 @@ def clear_resources(self, where: Mapping[str, Any] | None = None) -> dict[str, R
                     modality=row.modality,
                     local_path=row.local_path,
                     caption=row.caption,
-                    embedding=self._normalize_embedding(row.embedding_json),
+                    embedding=row.embedding,
                     created_at=row.created_at,
                     updated_at=row.updated_at,
                     **self._scope_kwargs_from(row),
@@ -163,7 +163,7 @@ def create_resource(
             modality=modality,
             local_path=local_path,
             caption=caption,
-            embedding_json=self._prepare_embedding(embedding),
+            embedding=embedding,
             created_at=now,
             updated_at=now,
             **user_data,