fix: harden source startup script

start-aivideo.bat

@@ -3,22 +3,33 @@ setlocal
 
 set "ROOT=%~dp0"
 set "BACKEND_DIR=%ROOT%backend"
-set "VENV_PYTHON=%BACKEND_DIR%\.venv\Scripts\python.exe"
+set "VENV_DIR=%BACKEND_DIR%\.venv"
-set "SOURCE_BACKEND_ENV=set DATABASE_URL=sqlite:///./aivideo.sqlite3 && set CELERY_TASK_ALWAYS_EAGER=true && set STORAGE_PROVIDER=local && set LOCAL_STORAGE_PATH=storage_data && set STORAGE_PUBLIC_BASE_URL=http://127.0.0.1:8000/storage"
+set "VENV_PYTHON=%VENV_DIR%\Scripts\python.exe"
+
+if /i "%~1"==":run_backend" goto run_backend
+if /i "%~1"==":run_frontend" goto run_frontend
+
 cd /d "%ROOT%"
 
 echo [1/6] Checking Python...
 set "PYTHON_CMD="
 where py >nul 2>nul
+if not errorlevel 1 (
+  py -3 -c "import sys" >nul 2>nul
   if not errorlevel 1 set "PYTHON_CMD=py -3"
-
-if not defined PYTHON_CMD (
-  where python >nul 2>nul
-  if not errorlevel 1 set "PYTHON_CMD=python"
 )
 
 if not defined PYTHON_CMD (
-  echo Python was not found in PATH.
+  where python >nul 2>nul
+  if not errorlevel 1 (
+    python -c "import sys" >nul 2>nul
+    if not errorlevel 1 set "PYTHON_CMD=python"
+  )
+)
+
+if not defined PYTHON_CMD (
+  echo A working Python 3 installation was not found.
+  echo Install Python 3.11 or later, then make sure py -3 or python works in a new terminal.
   pause
   exit /b 1
 )
@@ -41,9 +52,25 @@ if exist "%BACKEND_DIR%\.env" (
   echo The backend will start with built-in defaults ^(SQLite, local storage, mock task flow^).
 )
 
-if not exist "%VENV_PYTHON%" (
+set "VENV_READY="
+if exist "%VENV_PYTHON%" (
+  "%VENV_PYTHON%" -c "import sys" >nul 2>nul
+  if not errorlevel 1 set "VENV_READY=1"
+)
+
+if not defined VENV_READY (
+  if exist "%VENV_DIR%" (
+    echo Existing backend virtual environment is broken or stale. Recreating it...
+    rmdir /s /q "%VENV_DIR%"
+    if exist "%VENV_DIR%" (
+      echo Failed to remove the broken backend virtual environment.
+      pause
+      exit /b 1
+    )
+  )
+
   echo [4/6] Creating backend virtual environment...
-  call %PYTHON_CMD% -m venv "%BACKEND_DIR%\.venv"
+  %PYTHON_CMD% -m venv "%VENV_DIR%"
   if errorlevel 1 (
     echo Failed to create backend virtual environment.
     pause
@@ -51,7 +78,7 @@ if not exist "%VENV_PYTHON%" (
   )
 
   echo Installing backend dependencies...
-  call "%VENV_PYTHON%" -m pip install --disable-pip-version-check -r "%BACKEND_DIR%\requirements.txt"
+  "%VENV_PYTHON%" -m pip install --disable-pip-version-check -r "%BACKEND_DIR%\requirements.txt"
   if errorlevel 1 (
     echo Failed to install backend dependencies.
     pause
@@ -74,8 +101,8 @@ if not exist "%ROOT%node_modules" (
 )
 
 echo [6/6] Starting backend and unified frontend...
-start "AIVideo Backend" cmd /k "cd /d ""%BACKEND_DIR%"" && %SOURCE_BACKEND_ENV% && ""%VENV_PYTHON%"" -m uvicorn app.main:app --reload --host 0.0.0.0 --port 8000"
+start "AIVideo Backend" cmd /k call "%~f0" :run_backend
-start "AIVideo Frontend" cmd /k "cd /d ""%ROOT%"" && npm run dev"
+start "AIVideo Frontend" cmd /k call "%~f0" :run_frontend
 
 echo.
 echo User UI:   http://localhost:3000
@@ -84,3 +111,19 @@ echo API:       http://localhost:8000
 echo.
 echo Two windows have been opened for backend and frontend.
 pause
+goto :eof
+
+:run_backend
+cd /d "%BACKEND_DIR%"
+set "DATABASE_URL=sqlite:///./aivideo.sqlite3"
+set "CELERY_TASK_ALWAYS_EAGER=true"
+set "STORAGE_PROVIDER=local"
+set "LOCAL_STORAGE_PATH=storage_data"
+set "STORAGE_PUBLIC_BASE_URL=http://127.0.0.1:8000/storage"
+"%VENV_PYTHON%" -m uvicorn app.main:app --reload --host 0.0.0.0 --port 8000
+goto :eof
+
+:run_frontend
+cd /d "%ROOT%"
+npm run dev
+goto :eof