launcher: portable Python fallback + auto-install VC++ runtime

When no system Python is found, run.bat downloads an embeddable Python 3.12 into .pyenv/ and uses that. When onnxruntime fails to load due to missing Visual C++ 2015-2022 redistributable, app.py auto-downloads vc_redist.x64.exe, runs it elevated via UAC, then re-launches so the DLL load is retried in a fresh process.

web_interface/app.py

@@ -4,6 +4,10 @@ Oppai ONNX tagger — single-file launcher.
 First run: creates `.venv/`, installs requirements, re-execs inside the venv,
 then starts a local Gradio web UI on http://127.0.0.1:7860 .
 
+If the user has no Python at all, `run.bat` instead drops a portable Python
+into `.pyenv/` and uses that. In that case `app.py` skips venv creation and
+installs requirements directly into the portable Python's site-packages.
+
 Subsequent runs: skip install (marker file) and start the UI immediately.
 
 For most users:
@@ -34,6 +38,17 @@ ROOT = Path(__file__).resolve().parent
 VENV_DIR = ROOT / ".venv"
 MARKER = VENV_DIR / ".bootstrapped"
 
+# Portable Python lives here when run.bat had to download one because no
+# system Python was available. When app.py is launched by .pyenv/python.exe,
+# we install requirements directly into that interpreter — no venv needed.
+PYENV_DIR = ROOT / ".pyenv"
+PYENV_MARKER = PYENV_DIR / ".bootstrapped"
+
+# Microsoft Visual C++ 2015-2022 redistributable (x64). onnxruntime's native
+# DLLs depend on this; if it's missing the import fails with
+# "DLL load failed while importing onnxruntime_pybind11_state".
+VC_REDIST_URL = "https://aka.ms/vs/17/release/vc_redist.x64.exe"
+
 # Default folder if it exists; otherwise the first auto-discovered folder
 # next to this script is used. Override with --model-dir or the UI picker.
 DEFAULT_MODEL_DIR = ROOT / "V1.1_onnx"
@@ -114,6 +129,170 @@ def _bootstrap(force_reinstall: bool) -> None:
     sys.exit(subprocess.call([str(py), str(Path(__file__).resolve()), *args]))
 
 
+# ---------------------------------------------------------------------------
+# Portable-Python bootstrap (run.bat path when no system Python exists)
+# ---------------------------------------------------------------------------
+
+def _running_portable_python() -> bool:
+    """True when sys.executable lives inside ROOT/.pyenv/."""
+    try:
+        return Path(sys.executable).resolve().parent == PYENV_DIR.resolve()
+    except OSError:
+        return False
+
+
+def _bootstrap_portable(force_reinstall: bool) -> None:
+    """Install pip + requirements directly into the embedded Python.
+
+    Embeddable Python ships without pip and disables `import site` by default,
+    so we fix both before pip-installing the rest. No re-exec is needed —
+    we're already running inside the target interpreter.
+    """
+    py = Path(sys.executable)
+
+    # 1) Enable site-packages by uncommenting `import site` in pythonXY._pth.
+    pth_files = sorted(py.parent.glob("python*._pth"))
+    for pth in pth_files:
+        try:
+            text = pth.read_text(encoding="utf-8")
+        except OSError:
+            continue
+        new_text = text
+        for needle in ("#import site", "# import site"):
+            if needle in new_text:
+                new_text = new_text.replace(needle, "import site")
+        if new_text != text:
+            try:
+                pth.write_text(new_text, encoding="utf-8")
+                print(f"[bootstrap] Enabled site-packages in {pth.name}.")
+            except OSError as e:
+                print(f"[bootstrap] Could not edit {pth}: {e}")
+
+    # 2) Install pip if missing.
+    has_pip = subprocess.call(
+        [str(py), "-m", "pip", "--version"],
+        stdout=subprocess.DEVNULL,
+        stderr=subprocess.DEVNULL,
+    ) == 0
+    if not has_pip:
+        print("[bootstrap] Installing pip into portable Python ...")
+        import urllib.request
+        getpip = py.parent / "_get-pip.py"
+        try:
+            urllib.request.urlretrieve("https://bootstrap.pypa.io/get-pip.py", getpip)
+            subprocess.check_call([str(py), str(getpip), "--no-warn-script-location"])
+        finally:
+            try:
+                getpip.unlink()
+            except OSError:
+                pass
+
+    # 3) Install requirements (skipped if marker says we already did it).
+    needs_install = force_reinstall or not PYENV_MARKER.exists()
+    if needs_install:
+        print("[bootstrap] Upgrading pip ...")
+        subprocess.check_call([str(py), "-m", "pip", "install", "--upgrade", "pip"])
+        print(f"[bootstrap] Installing: {', '.join(REQUIREMENTS)}")
+        subprocess.check_call([str(py), "-m", "pip", "install", *REQUIREMENTS])
+        PYENV_MARKER.write_text("ok\n", encoding="utf-8")
+    else:
+        print("[bootstrap] Requirements already installed (delete .pyenv/.bootstrapped to redo).")
+
+
+# ---------------------------------------------------------------------------
+# onnxruntime / Visual C++ runtime recovery
+# ---------------------------------------------------------------------------
+
+def _looks_like_vcredist_failure(err: BaseException) -> bool:
+    """Heuristic: did onnxruntime fail to load because VC++ runtime DLLs
+    aren't on the box? The exact wording varies slightly by Windows version
+    but always mentions the failed DLL by name."""
+    if os.name != "nt":
+        return False
+    msg = str(err)
+    return "DLL load failed" in msg and "onnxruntime_pybind11_state" in msg
+
+
+def _install_vcredist_with_uac() -> bool:
+    """Download vc_redist.x64.exe and run it elevated. Returns True on
+    apparent success (exit 0 or 3010 = success-pending-reboot)."""
+    if os.name != "nt":
+        return False
+    import urllib.request
+    dest = ROOT / ".vc_redist.x64.exe"
+    print(f"[runtime] Downloading {VC_REDIST_URL} ...")
+    try:
+        urllib.request.urlretrieve(VC_REDIST_URL, dest)
+    except Exception as e:  # noqa: BLE001
+        print(f"[runtime] Download failed: {e}")
+        return False
+
+    # Start-Process -Verb RunAs is what triggers the UAC prompt; -Wait blocks
+    # until the installer exits so we can read its exit code. Apostrophes in
+    # the path are escaped by doubling for PowerShell's single-quote syntax.
+    ps_dest = str(dest).replace("'", "''")
+    ps_cmd = (
+        "$ErrorActionPreference='Stop';"
+        f"$p = Start-Process -FilePath '{ps_dest}' "
+        "-ArgumentList '/install','/quiet','/norestart' "
+        "-Verb RunAs -Wait -PassThru;"
+        "exit $p.ExitCode"
+    )
+    print("[runtime] Launching installer — accept the UAC prompt to continue.")
+    try:
+        rc = subprocess.call(
+            ["powershell", "-NoProfile", "-ExecutionPolicy", "Bypass", "-Command", ps_cmd]
+        )
+    except OSError as e:
+        print(f"[runtime] Could not launch installer: {e}")
+        rc = -1
+    finally:
+        try:
+            dest.unlink()
+        except OSError:
+            pass
+
+    if rc in (0, 3010):
+        if rc == 3010:
+            print("[runtime] Install succeeded but Windows requested a reboot.")
+        return True
+    if rc == 1602 or rc == 1223:
+        print("[runtime] Install was cancelled at the UAC prompt.")
+    else:
+        print(f"[runtime] Installer exited with code {rc}.")
+    return False
+
+
+def _recover_and_relaunch_after_vcredist() -> None:
+    """Try to install the VC++ redistributable, then re-exec the launcher so
+    the onnxruntime DLL gets a fresh load attempt. Windows caches failed DLL
+    loads within a process, so re-importing in-place doesn't work."""
+    print()
+    print("=" * 60)
+    print("  onnxruntime failed to load")
+    print("=" * 60)
+    print("This almost always means the Microsoft Visual C++ 2015-2022")
+    print("Redistributable (x64) is missing on this Windows machine.")
+    print("Trying to install it for you now — you'll see a UAC prompt.")
+    print()
+
+    if not _install_vcredist_with_uac():
+        print()
+        print("Manual fix:")
+        print(f"  1. Download {VC_REDIST_URL}")
+        print("  2. Run it (accept the UAC prompt)")
+        print("  3. Re-run this script")
+        print()
+        print("If install keeps failing, your CPU may lack AVX2 support, which")
+        print("modern onnxruntime wheels require. Most CPUs from 2014+ have it.")
+        sys.exit(1)
+
+    args = [a for a in sys.argv[1:] if a != "--reinstall"]
+    print("\n[runtime] Visual C++ runtime installed. Re-launching the app ...\n")
+    rc = subprocess.call([sys.executable, str(Path(__file__).resolve()), *args])
+    sys.exit(rc)
+
+
 # ---------------------------------------------------------------------------
 # App
 # ---------------------------------------------------------------------------
@@ -284,7 +463,13 @@ def _run_app() -> None:
     import json
 
     import numpy as np
-    import onnxruntime as ort
+    try:
+        import onnxruntime as ort
+    except ImportError as e:
+        if _looks_like_vcredist_failure(e):
+            _recover_and_relaunch_after_vcredist()
+            sys.exit(1)  # only reached if recover failed without exiting
+        raise
     import gradio as gr
     from PIL import Image
 
@@ -655,6 +840,14 @@ def main() -> None:
             pass
 
     force = "--reinstall" in sys.argv[1:]
+
+    if _running_portable_python():
+        # run.bat downloaded an embeddable Python because the user had none.
+        # Install requirements directly into it; no venv re-exec needed.
+        _bootstrap_portable(force_reinstall=force)
+        _run_app()
+        return
+
     if not _in_target_venv():
         _bootstrap(force_reinstall=force)
         return  # _bootstrap re-execs and exits

web_interface/run.bat

@@ -8,11 +8,17 @@ chcp 65001 >nul 2>nul
 set "PYTHONUTF8=1"
 set "PYTHONIOENCODING=utf-8"
 
-rem Pick a Python launcher. Try py first (works on most python.org installs),
-rem then `python`, then `python3`. enabledelayedexpansion + !ERRORLEVEL! is
-rem required so each check reads the value AFTER the preceding `where` runs.
+rem Pick a Python launcher. Order:
+rem   1. .pyenv\python.exe — portable Python downloaded by a previous run
+rem   2. py / python / python3 — user's system Python
+rem   3. Download a portable Python on the fly (no admin, no PATH changes)
 set "PYCMD="
 
+if exist "%~dp0.pyenv\python.exe" (
+    set "PYCMD=%~dp0.pyenv\python.exe"
+    goto :launch
+)
+
 where py >nul 2>nul
 if !ERRORLEVEL! EQU 0 set "PYCMD=py"
 
@@ -26,20 +32,48 @@ if not defined PYCMD (
     if !ERRORLEVEL! EQU 0 set "PYCMD=python3"
 )
 
-if not defined PYCMD (
-    echo [run.bat] No Python found on PATH.
-    echo [run.bat] Install Python 3.10+ from https://www.python.org/downloads/
-    echo [run.bat] During install, tick "Add Python to PATH".
+if defined PYCMD goto :launch
+
+echo [run.bat] No Python detected on this machine.
+echo [run.bat] Downloading a portable Python (~30 MB) into .pyenv\ next to this script.
+echo [run.bat] Nothing is installed system-wide; delete .pyenv\ to remove it.
+echo.
+
+powershell -NoProfile -ExecutionPolicy Bypass -Command ^
+  "$ErrorActionPreference='Stop';" ^
+  "$ver='3.12.7';" ^
+  "$dest='%~dp0.pyenv';" ^
+  "$zip=Join-Path $env:TEMP 'oppai-py-embed.zip';" ^
+  "[void](New-Item -ItemType Directory -Force -Path $dest);" ^
+  "Invoke-WebRequest -UseBasicParsing -Uri \"https://www.python.org/ftp/python/$ver/python-$ver-embed-amd64.zip\" -OutFile $zip;" ^
+  "Expand-Archive -Path $zip -DestinationPath $dest -Force;" ^
+  "Remove-Item $zip -Force"
+
+if !ERRORLEVEL! NEQ 0 (
+    echo.
+    echo [run.bat] Failed to download portable Python.
+    echo [run.bat] Check your internet connection, or install Python 3.10-3.12
+    echo           from https://www.python.org/downloads/ ^(tick "Add Python to PATH"^)
+    echo           and re-run this script.
+    pause
+    exit /b 1
+)
+
+if not exist "%~dp0.pyenv\python.exe" (
+    echo [run.bat] Portable Python download finished but python.exe is missing.
+    echo [run.bat] Try deleting .pyenv\ and re-running, or install Python manually.
     pause
     exit /b 1
 )
 
+set "PYCMD=%~dp0.pyenv\python.exe"
+
+:launch
 echo [run.bat] Using !PYCMD! to launch app.py.
-echo [run.bat] First run creates .venv and installs ~500 MB of packages.
-echo [run.bat] That can take several minutes; it only happens once.
+echo [run.bat] First run installs ~500 MB of packages; that only happens once.
 echo.
 
-!PYCMD! "%~dp0app.py" %*
+"!PYCMD!" "%~dp0app.py" %*
 set "EXITCODE=!ERRORLEVEL!"
 
 if !EXITCODE! NEQ 0 (