Fix remaining blocking I/O calls and N+1 project query

- tab_batch_ng.py: async create_batch with to_thread save/sync
- tab_raw_ng.py: async do_save with to_thread, replace deepcopy
  with dict comprehension for display data
- main.py: async create_new with to_thread save
- tab_projects_ng.py: replace per-project count_data_files with
  single list_projects_with_file_counts JOIN query
- db.py: add list_projects_with_file_counts method

Zero blocking I/O calls remain in UI callbacks.

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

db.py

@@ -93,6 +93,16 @@ class ProjectDB:
         ).fetchall()
         return [dict(r) for r in rows]
 
+    def list_projects_with_file_counts(self) -> list[dict]:
+        """List projects with data file counts in a single query."""
+        rows = self.conn.execute(
+            "SELECT p.id, p.name, p.folder_path, p.description, p.created_at, p.updated_at, "
+            "COUNT(df.id) AS file_count "
+            "FROM projects p LEFT JOIN data_files df ON df.project_id = p.id "
+            "GROUP BY p.id ORDER BY p.name"
+        ).fetchall()
+        return [dict(r) for r in rows]
+
     def get_project(self, name: str) -> dict | None:
         row = self.conn.execute(
             "SELECT id, name, folder_path, description, created_at, updated_at "

main.py

@@ -476,7 +476,7 @@ def render_sidebar(state: AppState, dual_pane: dict):
             with ui.expansion('Create New JSON'):
                 new_fn_input = ui.input('Filename', placeholder='my_prompt_vace').classes('w-full')
 
-                def create_new():
+                async def create_new():
                     fn = new_fn_input.value
                     if not fn:
                         return
@@ -485,7 +485,7 @@ def render_sidebar(state: AppState, dual_pane: dict):
                     path = state.current_dir / fn
                     first_item = copy.deepcopy(DEFAULTS)
                     first_item[KEY_SEQUENCE_NUMBER] = 1
-                    save_json(path, {KEY_BATCH_DATA: [first_item]})
+                    await asyncio.to_thread(save_json, path, {KEY_BATCH_DATA: [first_item]})
                     new_fn_input.set_value('')
                     render_file_list.refresh()
 

tab_batch_ng.py

@@ -199,7 +199,7 @@ def render_batch_processor(state: AppState):
         ui.label('This is a Single file. To use Batch mode, create a copy.').classes(
             'text-warning')
 
-        def create_batch():
+        async def create_batch():
             new_name = f'batch_{file_path.name}'
             new_path = file_path.parent / new_name
             if new_path.exists():
@@ -211,9 +211,9 @@ def render_batch_processor(state: AppState):
             first_item[KEY_SEQUENCE_NUMBER] = 1
             new_data = {KEY_BATCH_DATA: [first_item], KEY_HISTORY_TREE: {},
                         KEY_PROMPT_HISTORY: []}
-            save_json(new_path, new_data)
+            await asyncio.to_thread(save_json, new_path, new_data)
             if state.db_enabled and state.current_project and state.db:
-                sync_to_db(state.db, state.current_project, new_path, new_data)
+                await asyncio.to_thread(sync_to_db, state.db, state.current_project, new_path, new_data)
             ui.notify(f'Created {new_name}', type='positive')
 
         ui.button('Create Batch Copy', icon='content_copy', on_click=create_batch)

tab_projects_ng.py

@@ -60,8 +60,8 @@ def render_projects_tab(state: AppState):
             ui.button('Create Project', icon='add', on_click=create_project).classes('w-full')
 
         # --- Active project indicator ---
-        # Fetch once and reuse in render_project_list
-        _cached_projects = state.db.list_projects()
+        # Fetch once with file counts and reuse in render_project_list
+        _cached_projects = state.db.list_projects_with_file_counts()
 
         if state.current_project:
             # Check if active project actually exists in the database
@@ -102,7 +102,7 @@ def render_projects_tab(state: AppState):
         @ui.refreshable
         def render_project_list():
             nonlocal _cached_projects
-            projects = state.db.list_projects()
+            projects = state.db.list_projects_with_file_counts()
             _cached_projects = projects
             if not projects:
                 ui.label('No projects yet. Create one above.').classes('text-caption q-pa-md')
@@ -119,8 +119,7 @@ def render_projects_tab(state: AppState):
                             if proj['description']:
                                 ui.label(proj['description']).classes('text-caption')
                             ui.label(f'Path: {proj["folder_path"]}').classes('text-caption')
-                            file_count = state.db.count_data_files(proj['id'])
-                            ui.label(f'{file_count} data file(s)').classes('text-caption')
+                            ui.label(f'{proj["file_count"]} data file(s)').classes('text-caption')
 
                         with ui.row().classes('q-gutter-xs'):
                             if not is_active:

tab_raw_ng.py

@@ -1,4 +1,4 @@
-import copy
+import asyncio
 import json
 
 from nicegui import ui
@@ -21,11 +21,10 @@ def render_raw_editor(state: AppState):
 
         @ui.refreshable
         def render_editor():
-            # Prepare display data
+            # Prepare display data — shallow copy, just pop keys
             if hide_history.value:
-                display_data = copy.deepcopy(data)
-                display_data.pop(KEY_HISTORY_TREE, None)
-                display_data.pop(KEY_PROMPT_HISTORY, None)
+                display_data = {k: v for k, v in data.items()
+                                if k not in (KEY_HISTORY_TREE, KEY_PROMPT_HISTORY)}
             else:
                 display_data = data
 
@@ -40,7 +39,7 @@ def render_raw_editor(state: AppState):
                 value=json_str,
             ).classes('w-full font-mono').props('outlined rows=30')
 
-            def do_save():
+            async def do_save():
                 try:
                     input_data = json.loads(text_area.value)
 
@@ -51,9 +50,9 @@ def render_raw_editor(state: AppState):
                         if KEY_PROMPT_HISTORY in data:
                             input_data[KEY_PROMPT_HISTORY] = data[KEY_PROMPT_HISTORY]
 
-                    save_json(file_path, input_data)
+                    await asyncio.to_thread(save_json, file_path, input_data)
                     if state.db_enabled and state.current_project and state.db:
-                        sync_to_db(state.db, state.current_project, file_path, input_data)
+                        await asyncio.to_thread(sync_to_db, state.db, state.current_project, file_path, input_data)
 
                     data.clear()
                     data.update(input_data)