feat(v2): Auto-migrate v1 .msgs data to SQLite on first startup

Reads the existing .msgs JSONL file and imports channel messages and DMs
into the v2 SQLite database. Runs automatically when device connects and
DB is empty. Handles sender parsing, pubkey resolution, and FK constraints.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_database.py

@@ -413,3 +413,83 @@ class TestPaths:
         db.insert_path('aa', pkt_payload='PKT', path='A>B>C', snr=-5.0, path_len=3)
         stats = db.get_stats()
         assert stats['paths'] == 1
+
+
+# ================================================================
+# v1 Migration
+# ================================================================
+
+class TestV1Migration:
+    def _write_msgs(self, path, lines):
+        """Write JSONL lines to a .msgs file."""
+        import json
+        with open(path, 'w') as f:
+            for line in lines:
+                f.write(json.dumps(line) + '\n')
+
+    def test_migrate_channel_messages(self, db):
+        import tempfile, json
+        from app.migrate_v1 import migrate_v1_data, should_migrate
+
+        with tempfile.TemporaryDirectory() as tmp:
+            data_dir = Path(tmp)
+            self._write_msgs(data_dir / 'TestDevice.msgs', [
+                {'type': 'CHAN', 'channel_idx': 0, 'text': 'Alice: Hello world', 'timestamp': 1000, 'SNR': -5.0, 'path_len': 2},
+                {'type': 'SENT_CHAN', 'channel_idx': 0, 'text': 'My message', 'timestamp': 1001, 'sender': 'TestDevice'},
+                {'type': 'CHAN', 'channel_idx': 1, 'text': 'Bob: On channel 1', 'timestamp': 1002},
+            ])
+
+            assert should_migrate(db, data_dir, 'TestDevice')
+
+            result = migrate_v1_data(db, data_dir, 'TestDevice')
+            assert result['status'] == 'completed'
+            assert result['channel_messages'] == 3
+
+            msgs = db.get_channel_messages()
+            assert len(msgs) == 3
+            assert msgs[0]['sender'] == 'Alice'
+            assert msgs[0]['content'] == 'Hello world'
+            assert msgs[1]['sender'] == 'TestDevice'
+            assert msgs[1]['content'] == 'My message'
+            assert msgs[1]['is_own'] == 1
+            assert msgs[2]['sender'] == 'Bob'
+            assert msgs[2]['channel_idx'] == 1
+
+    def test_migrate_dm_messages(self, db):
+        import tempfile, json
+        from app.migrate_v1 import migrate_v1_data
+
+        with tempfile.TemporaryDirectory() as tmp:
+            data_dir = Path(tmp)
+            self._write_msgs(data_dir / 'TestDevice.msgs', [
+                {'type': 'PRIV', 'text': 'Hello from Alice', 'timestamp': 2000, 'pubkey_prefix': 'aabb', 'name': 'Alice'},
+                {'type': 'SENT_MSG', 'text': 'Reply to Alice', 'timestamp': 2001, 'recipient': 'Alice', 'txt_type': 0},
+                {'type': 'SENT_MSG', 'text': 'Channel sent', 'timestamp': 2002, 'txt_type': 1},  # should be skipped
+            ])
+
+            result = migrate_v1_data(db, data_dir, 'TestDevice')
+            assert result['status'] == 'completed'
+            assert result['direct_messages'] == 2
+            assert result['skipped'] == 1
+
+    def test_should_migrate_false_when_db_has_data(self, db):
+        import tempfile
+        from app.migrate_v1 import should_migrate
+
+        with tempfile.TemporaryDirectory() as tmp:
+            data_dir = Path(tmp)
+            self._write_msgs(data_dir / 'Dev.msgs', [
+                {'type': 'CHAN', 'text': 'Test: msg', 'timestamp': 1000},
+            ])
+
+            # Add a message to DB first
+            db.insert_channel_message(0, 'X', 'Existing', int(time.time()))
+
+            assert not should_migrate(db, data_dir, 'Dev')
+
+    def test_should_migrate_false_when_no_msgs_file(self, db):
+        import tempfile
+        from app.migrate_v1 import should_migrate
+
+        with tempfile.TemporaryDirectory() as tmp:
+            assert not should_migrate(db, Path(tmp), 'NoDevice')