[loop-cycle-951] refactor: break up _migrate_schema() (#552) (#558)

src/timmy/memory_system.py

@@ -98,6 +98,73 @@ def _get_table_columns(conn: sqlite3.Connection, table_name: str) -> set[str]:
     return {row[1] for row in cursor.fetchall()}
 
 
+def _migrate_episodes(conn: sqlite3.Connection) -> None:
+    """Migrate episodes table rows into the unified memories table."""
+    logger.info("Migration: Converting episodes table to memories")
+    try:
+        cols = _get_table_columns(conn, "episodes")
+        context_type_col = "context_type" if "context_type" in cols else "'conversation'"
+
+        conn.execute(f"""
+            INSERT INTO memories (
+                id, content, memory_type, source, embedding,
+                metadata, agent_id, task_id, session_id,
+                created_at, access_count, last_accessed
+            )
+            SELECT
+                id, content,
+                COALESCE({context_type_col}, 'conversation'),
+                COALESCE(source, 'agent'),
+                embedding,
+                metadata, agent_id, task_id, session_id,
+                COALESCE(timestamp, datetime('now')), 0, NULL
+            FROM episodes
+        """)
+        conn.execute("DROP TABLE episodes")
+        logger.info("Migration: Migrated episodes to memories")
+    except sqlite3.Error as exc:
+        logger.warning("Migration: Failed to migrate episodes: %s", exc)
+
+
+def _migrate_chunks(conn: sqlite3.Connection) -> None:
+    """Migrate chunks table rows into the unified memories table."""
+    logger.info("Migration: Converting chunks table to memories")
+    try:
+        cols = _get_table_columns(conn, "chunks")
+
+        id_col = "id" if "id" in cols else "CAST(rowid AS TEXT)"
+        content_col = "content" if "content" in cols else "text"
+        source_col = (
+            "filepath" if "filepath" in cols else ("source" if "source" in cols else "'vault'")
+        )
+        embedding_col = "embedding" if "embedding" in cols else "NULL"
+        created_col = "created_at" if "created_at" in cols else "datetime('now')"
+
+        conn.execute(f"""
+            INSERT INTO memories (
+                id, content, memory_type, source, embedding,
+                created_at, access_count
+            )
+            SELECT
+                {id_col}, {content_col}, 'vault_chunk', {source_col},
+                {embedding_col}, {created_col}, 0
+            FROM chunks
+        """)
+        conn.execute("DROP TABLE chunks")
+        logger.info("Migration: Migrated chunks to memories")
+    except sqlite3.Error as exc:
+        logger.warning("Migration: Failed to migrate chunks: %s", exc)
+
+
+def _drop_legacy_table(conn: sqlite3.Connection, table: str) -> None:
+    """Drop a legacy table if it exists."""
+    try:
+        conn.execute(f"DROP TABLE {table}")  # noqa: S608
+        logger.info("Migration: Dropped old %s table", table)
+    except sqlite3.Error as exc:
+        logger.warning("Migration: Failed to drop %s: %s", table, exc)
+
+
 def _migrate_schema(conn: sqlite3.Connection) -> None:
     """Migrate from old three-table schema to unified memories table.
 
@@ -110,78 +177,16 @@ def _migrate_schema(conn: sqlite3.Connection) -> None:
     tables = {row[0] for row in cursor.fetchall()}
 
     has_memories = "memories" in tables
-    has_episodes = "episodes" in tables
-    has_chunks = "chunks" in tables
-    has_facts = "facts" in tables
 
-    # Check if we need to migrate (old schema exists)
-    if not has_memories and (has_episodes or has_chunks or has_facts):
+    if not has_memories and (tables & {"episodes", "chunks", "facts"}):
         logger.info("Migration: Creating unified memories table")
-        # Schema will be created by _ensure_schema above
 
-    # Migrate episodes -> memories
-    if has_episodes and has_memories:
-        logger.info("Migration: Converting episodes table to memories")
-        try:
-            cols = _get_table_columns(conn, "episodes")
-            context_type_col = "context_type" if "context_type" in cols else "'conversation'"
-
-            conn.execute(f"""
-                INSERT INTO memories (
-                    id, content, memory_type, source, embedding,
-                    metadata, agent_id, task_id, session_id,
-                    created_at, access_count, last_accessed
-                )
-                SELECT 
-                    id, content, 
-                    COALESCE({context_type_col}, 'conversation'),
-                    COALESCE(source, 'agent'),
-                    embedding,
-                    metadata, agent_id, task_id, session_id,
-                    COALESCE(timestamp, datetime('now')), 0, NULL
-                FROM episodes
-            """)
-            conn.execute("DROP TABLE episodes")
-            logger.info("Migration: Migrated episodes to memories")
-        except sqlite3.Error as exc:
-            logger.warning("Migration: Failed to migrate episodes: %s", exc)
-
-    # Migrate chunks -> memories as vault_chunk
-    if has_chunks and has_memories:
-        logger.info("Migration: Converting chunks table to memories")
-        try:
-            cols = _get_table_columns(conn, "chunks")
-
-            id_col = "id" if "id" in cols else "CAST(rowid AS TEXT)"
-            content_col = "content" if "content" in cols else "text"
-            source_col = (
-                "filepath" if "filepath" in cols else ("source" if "source" in cols else "'vault'")
-            )
-            embedding_col = "embedding" if "embedding" in cols else "NULL"
-            created_col = "created_at" if "created_at" in cols else "datetime('now')"
-
-            conn.execute(f"""
-                INSERT INTO memories (
-                    id, content, memory_type, source, embedding,
-                    created_at, access_count
-                )
-                SELECT 
-                    {id_col}, {content_col}, 'vault_chunk', {source_col},
-                    {embedding_col}, {created_col}, 0
-                FROM chunks
-            """)
-            conn.execute("DROP TABLE chunks")
-            logger.info("Migration: Migrated chunks to memories")
-        except sqlite3.Error as exc:
-            logger.warning("Migration: Failed to migrate chunks: %s", exc)
-
-    # Drop old tables
-    if has_facts:
-        try:
-            conn.execute("DROP TABLE facts")
-            logger.info("Migration: Dropped old facts table")
-        except sqlite3.Error as exc:
-            logger.warning("Migration: Failed to drop facts: %s", exc)
+    if "episodes" in tables and has_memories:
+        _migrate_episodes(conn)
+    if "chunks" in tables and has_memories:
+        _migrate_chunks(conn)
+    if "facts" in tables:
+        _drop_legacy_table(conn, "facts")
 
     conn.commit()