Refactoring

lib/data/database/app_database.dart

@@ -1,17 +1,23 @@
-import 'package:drift/drift.dart';
-import 'package:drift/native.dart';
-import 'package:path_provider/path_provider.dart';
-import 'package:path/path.dart' as p;
-import 'package:trainhub_flutter/core/constants/app_constants.dart';
-import 'package:trainhub_flutter/data/database/daos/exercise_dao.dart';
-import 'package:trainhub_flutter/data/database/daos/training_plan_dao.dart';
-import 'package:trainhub_flutter/data/database/daos/program_dao.dart';
-import 'package:trainhub_flutter/data/database/daos/analysis_dao.dart';
-import 'package:trainhub_flutter/data/database/daos/chat_dao.dart';
 import 'dart:io';
 
+import 'package:drift/drift.dart';
+import 'package:drift/native.dart';
+import 'package:path/path.dart' as p;
+import 'package:path_provider/path_provider.dart';
+import 'package:trainhub_flutter/core/constants/app_constants.dart';
+import 'package:trainhub_flutter/data/database/daos/analysis_dao.dart';
+import 'package:trainhub_flutter/data/database/daos/chat_dao.dart';
+import 'package:trainhub_flutter/data/database/daos/exercise_dao.dart';
+import 'package:trainhub_flutter/data/database/daos/knowledge_chunk_dao.dart';
+import 'package:trainhub_flutter/data/database/daos/program_dao.dart';
+import 'package:trainhub_flutter/data/database/daos/training_plan_dao.dart';
+
 part 'app_database.g.dart';
 
+// ---------------------------------------------------------------------------
+// Existing tables (unchanged)
+// ---------------------------------------------------------------------------
+
 class Exercises extends Table {
   TextColumn get id => text()();
   TextColumn get name => text()();
@@ -116,6 +122,35 @@ class ChatMessages extends Table {
   Set<Column> get primaryKey => {id};
 }
 
+// ---------------------------------------------------------------------------
+// v2: Knowledge base chunks
+// ---------------------------------------------------------------------------
+
+/// Stores text chunks and their JSON-encoded embedding vectors.
+/// Used for Retrieval-Augmented Generation (RAG) in the AI chat.
+class KnowledgeChunks extends Table {
+  /// UUID for this individual chunk.
+  TextColumn get id => text()();
+
+  /// All chunks from the same `addNote()` call share this ID.
+  TextColumn get sourceId => text()();
+
+  /// The raw text of the chunk (max ~500 chars).
+  TextColumn get content => text()();
+
+  /// JSON-encoded `List<double>` — the 768-dim Nomic embedding vector.
+  TextColumn get embedding => text()();
+
+  TextColumn get createdAt => text()();
+
+  @override
+  Set<Column> get primaryKey => {id};
+}
+
+// ---------------------------------------------------------------------------
+// Database class
+// ---------------------------------------------------------------------------
+
 @DriftDatabase(
   tables: [
     Exercises,
@@ -127,6 +162,7 @@ class ChatMessages extends Table {
     Annotations,
     ChatSessions,
     ChatMessages,
+    KnowledgeChunks, // added in schema v2
   ],
   daos: [
     ExerciseDao,
@@ -134,13 +170,24 @@ class ChatMessages extends Table {
     ProgramDao,
     AnalysisDao,
     ChatDao,
+    KnowledgeChunkDao, // added in schema v2
   ],
 )
 class AppDatabase extends _$AppDatabase {
   AppDatabase() : super(_openConnection());
 
   @override
-  int get schemaVersion => 1;
+  int get schemaVersion => 2;
+
+  @override
+  MigrationStrategy get migration => MigrationStrategy(
+        onUpgrade: (migrator, from, to) async {
+          // v1 → v2: add knowledge chunks table
+          if (from < 2) {
+            await migrator.createTable(knowledgeChunks);
+          }
+        },
+      );
 }
 
 LazyDatabase _openConnection() {