Improve performance on unread endpoint

app/migrations.py

@@ -233,6 +233,13 @@ async def run_migrations(conn: aiosqlite.Connection) -> int:
         await set_version(conn, 28)
         applied += 1
 
+    # Migration 29: Add covering index for unread counts query
+    if version < 29:
+        logger.info("Applying migration 29: add covering index for unread counts query")
+        await _migrate_029_add_unread_covering_index(conn)
+        await set_version(conn, 29)
+        applied += 1
+
     if applied > 0:
         logger.info(
             "Applied %d migration(s), schema now at version %d", applied, await get_version(conn)
@@ -1790,3 +1797,25 @@ async def _migrate_028_payload_hash_text_to_blob(conn: aiosqlite.Connection) ->
 
     await conn.commit()
     logger.info("Converted %d payload_hash values from TEXT to BLOB", total)
+
+
+async def _migrate_029_add_unread_covering_index(conn: aiosqlite.Connection) -> None:
+    """
+    Add a covering index for the unread counts query.
+
+    The /api/read-state/unreads endpoint runs three queries against messages.
+    The last-message-times query (GROUP BY type, conversation_key + MAX(received_at))
+    was doing a full table scan. This covering index lets SQLite resolve the
+    grouping and MAX entirely from the index without touching the table.
+    It also improves the unread count queries which filter on outgoing and received_at.
+    """
+    # Guard: table or columns may not exist in partial-schema test setups
+    cursor = await conn.execute("PRAGMA table_info(messages)")
+    columns = {row[1] for row in await cursor.fetchall()}
+    required = {"type", "conversation_key", "outgoing", "received_at"}
+    if required <= columns:
+        await conn.execute(
+            "CREATE INDEX IF NOT EXISTS idx_messages_unread_covering "
+            "ON messages(type, conversation_key, outgoing, received_at)"
+        )
+    await conn.commit()

tests/test_migrations.py

@@ -100,8 +100,8 @@ class TestMigration001:
             # Run migrations
             applied = await run_migrations(conn)
 
-            assert applied == 28  # All migrations run
-            assert await get_version(conn) == 28
+            assert applied == 29  # All migrations run
+            assert await get_version(conn) == 29
 
             # Verify columns exist by inserting and selecting
             await conn.execute(
@@ -183,9 +183,9 @@ class TestMigration001:
             applied1 = await run_migrations(conn)
             applied2 = await run_migrations(conn)
 
-            assert applied1 == 28  # All migrations run
+            assert applied1 == 29  # All migrations run
             assert applied2 == 0  # No migrations on second run
-            assert await get_version(conn) == 28
+            assert await get_version(conn) == 29
         finally:
             await conn.close()
 
@@ -246,8 +246,8 @@ class TestMigration001:
             applied = await run_migrations(conn)
 
             # All migrations applied (version incremented) but no error
-            assert applied == 28
-            assert await get_version(conn) == 28
+            assert applied == 29
+            assert await get_version(conn) == 29
         finally:
             await conn.close()
 
@@ -376,8 +376,8 @@ class TestMigration013:
 
             # Run migration 13 (plus 14-27 which also run)
             applied = await run_migrations(conn)
-            assert applied == 16
-            assert await get_version(conn) == 28
+            assert applied == 17
+            assert await get_version(conn) == 29
 
             # Verify bots array was created with migrated data
             cursor = await conn.execute("SELECT bots FROM app_settings WHERE id = 1")
@@ -497,7 +497,7 @@ class TestMigration018:
             assert await cursor.fetchone() is not None
 
             await run_migrations(conn)
-            assert await get_version(conn) == 28
+            assert await get_version(conn) == 29
 
             # Verify autoindex is gone
             cursor = await conn.execute(
@@ -575,8 +575,8 @@ class TestMigration018:
             await conn.commit()
 
             applied = await run_migrations(conn)
-            assert applied == 11  # Migrations 18-28 run (18+19 skip internally)
-            assert await get_version(conn) == 28
+            assert applied == 12  # Migrations 18-29 run (18+19 skip internally)
+            assert await get_version(conn) == 29
         finally:
             await conn.close()
 
@@ -648,7 +648,7 @@ class TestMigration019:
             assert await cursor.fetchone() is not None
 
             await run_migrations(conn)
-            assert await get_version(conn) == 28
+            assert await get_version(conn) == 29
 
             # Verify autoindex is gone
             cursor = await conn.execute(
@@ -714,8 +714,8 @@ class TestMigration020:
             assert (await cursor.fetchone())[0] == "delete"
 
             applied = await run_migrations(conn)
-            assert applied == 9  # Migrations 20-28
-            assert await get_version(conn) == 28
+            assert applied == 10  # Migrations 20-29
+            assert await get_version(conn) == 29
 
             # Verify WAL mode
             cursor = await conn.execute("PRAGMA journal_mode")
@@ -745,7 +745,7 @@ class TestMigration020:
             await set_version(conn, 20)
 
             applied = await run_migrations(conn)
-            assert applied == 8  # Migrations 21-28 still run
+            assert applied == 9  # Migrations 21-29 still run
 
             # Still WAL + INCREMENTAL
             cursor = await conn.execute("PRAGMA journal_mode")
@@ -803,8 +803,8 @@ class TestMigration028:
             await conn.commit()
 
             applied = await run_migrations(conn)
-            assert applied == 1
-            assert await get_version(conn) == 28
+            assert applied == 2
+            assert await get_version(conn) == 29
 
             # Verify payload_hash column is now BLOB
             cursor = await conn.execute("PRAGMA table_info(raw_packets)")
@@ -873,8 +873,8 @@ class TestMigration028:
             await conn.commit()
 
             applied = await run_migrations(conn)
-            assert applied == 1  # Version still bumped
-            assert await get_version(conn) == 28
+            assert applied == 2  # Version still bumped
+            assert await get_version(conn) == 29
 
             # Verify data unchanged
             cursor = await conn.execute("SELECT payload_hash FROM raw_packets")