[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

studio/backend/colab.py

@@ -7,8 +7,26 @@ Uses Colab's built-in proxy - no external tunneling needed!
 """
 
 from pathlib import Path
+import site
 import sys
 
+
+def _bootstrap_studio_venv() -> None:
+    """Expose the Studio venv's site-packages to the current interpreter.
+
+    On Colab, notebook cells run outside the venv subshell. Instead of
+    installing the full stack into system Python, we add the venv's
+    site-packages so that packages like structlog, fastapi, etc. are
+    importable from notebook cells.
+    """
+    venv_lib = Path.home() / ".unsloth" / "studio" / ".venv" / "lib"
+    for sp in venv_lib.glob("python*/site-packages"):
+        if str(sp) not in sys.path:
+            site.addsitedir(str(sp))
+
+
+_bootstrap_studio_venv()
+
 # Add backend to path early so local modules like loggers can be imported
 backend_path = str(Path(__file__).parent)
 if backend_path not in sys.path:

studio/backend/core/export/worker.py

@@ -40,59 +40,25 @@ def _activate_transformers_version(model_name: str) -> None:
     if backend_path not in sys.path:
         sys.path.insert(0, backend_path)
 
-    from utils.transformers_version import needs_transformers_5, _resolve_base_model
+    from utils.transformers_version import (
+        needs_transformers_5,
+        _resolve_base_model,
+        _ensure_venv_t5_exists,
+        _VENV_T5_DIR,
+    )
 
     resolved = _resolve_base_model(model_name)
     if needs_transformers_5(resolved):
-        venv_t5 = os.path.join(
-            os.path.expanduser("~"), ".unsloth", "studio", ".venv_t5"
-        )
-        if os.path.isdir(venv_t5):
-            sys.path.insert(0, venv_t5)
-            logger.info("Activated transformers 5.x from %s", venv_t5)
-        else:
-            # Fallback: pip install at runtime (slower, ~10-15s)
-            logger.warning(".venv_t5 not found at %s — installing at runtime", venv_t5)
-            import subprocess as sp
-
-            os.makedirs(venv_t5, exist_ok = True)
-            r1 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "transformers==5.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
+        if not _ensure_venv_t5_exists():
+            raise RuntimeError(
+                f"Cannot activate transformers 5.x: .venv_t5 missing at {_VENV_T5_DIR}"
             )
-            r2 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "huggingface_hub==1.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
-            )
-            if r1.returncode != 0 or r2.returncode != 0:
-                raise RuntimeError(
-                    f"Failed to install transformers 5.x into {venv_t5}. "
-                    f"pip returncode: transformers={r1.returncode}, huggingface_hub={r2.returncode}"
-                )
-            sys.path.insert(0, venv_t5)
+        if _VENV_T5_DIR not in sys.path:
+            sys.path.insert(0, _VENV_T5_DIR)
+        logger.info("Activated transformers 5.x from %s", _VENV_T5_DIR)
         # Propagate to child subprocesses (e.g. GGUF converter)
         _pp = os.environ.get("PYTHONPATH", "")
-        os.environ["PYTHONPATH"] = venv_t5 + (os.pathsep + _pp if _pp else "")
+        os.environ["PYTHONPATH"] = _VENV_T5_DIR + (os.pathsep + _pp if _pp else "")
     else:
         logger.info("Using default transformers (4.57.x) for %s", model_name)
 

studio/backend/core/inference/worker.py

@@ -42,59 +42,25 @@ def _activate_transformers_version(model_name: str) -> None:
     if backend_path not in sys.path:
         sys.path.insert(0, backend_path)
 
-    from utils.transformers_version import needs_transformers_5, _resolve_base_model
+    from utils.transformers_version import (
+        needs_transformers_5,
+        _resolve_base_model,
+        _ensure_venv_t5_exists,
+        _VENV_T5_DIR,
+    )
 
     resolved = _resolve_base_model(model_name)
     if needs_transformers_5(resolved):
-        venv_t5 = os.path.join(
-            os.path.expanduser("~"), ".unsloth", "studio", ".venv_t5"
-        )
-        if os.path.isdir(venv_t5):
-            sys.path.insert(0, venv_t5)
-            logger.info("Activated transformers 5.x from %s", venv_t5)
-        else:
-            # Fallback: pip install at runtime (slower, ~10-15s)
-            logger.warning(".venv_t5 not found at %s — installing at runtime", venv_t5)
-            import subprocess as sp
-
-            os.makedirs(venv_t5, exist_ok = True)
-            r1 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "transformers==5.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
+        if not _ensure_venv_t5_exists():
+            raise RuntimeError(
+                f"Cannot activate transformers 5.x: .venv_t5 missing at {_VENV_T5_DIR}"
             )
-            r2 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "huggingface_hub==1.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
-            )
-            if r1.returncode != 0 or r2.returncode != 0:
-                raise RuntimeError(
-                    f"Failed to install transformers 5.x into {venv_t5}. "
-                    f"pip returncode: transformers={r1.returncode}, huggingface_hub={r2.returncode}"
-                )
-            sys.path.insert(0, venv_t5)
+        if _VENV_T5_DIR not in sys.path:
+            sys.path.insert(0, _VENV_T5_DIR)
+        logger.info("Activated transformers 5.x from %s", _VENV_T5_DIR)
         # Propagate to child subprocesses (e.g. GGUF converter)
         _pp = os.environ.get("PYTHONPATH", "")
-        os.environ["PYTHONPATH"] = venv_t5 + (os.pathsep + _pp if _pp else "")
+        os.environ["PYTHONPATH"] = _VENV_T5_DIR + (os.pathsep + _pp if _pp else "")
     else:
         logger.info("Using default transformers (4.57.x) for %s", model_name)
 

studio/backend/core/training/worker.py

@@ -36,59 +36,25 @@ def _activate_transformers_version(model_name: str) -> None:
     if backend_path not in sys.path:
         sys.path.insert(0, backend_path)
 
-    from utils.transformers_version import needs_transformers_5, _resolve_base_model
+    from utils.transformers_version import (
+        needs_transformers_5,
+        _resolve_base_model,
+        _ensure_venv_t5_exists,
+        _VENV_T5_DIR,
+    )
 
     resolved = _resolve_base_model(model_name)
     if needs_transformers_5(resolved):
-        venv_t5 = os.path.join(
-            os.path.expanduser("~"), ".unsloth", "studio", ".venv_t5"
-        )
-        if os.path.isdir(venv_t5):
-            sys.path.insert(0, venv_t5)
-            logger.info("Activated transformers 5.x from %s", venv_t5)
-        else:
-            # Fallback: pip install at runtime (slower, ~10-15s)
-            logger.warning(".venv_t5 not found at %s — installing at runtime", venv_t5)
-            import subprocess as sp
-
-            os.makedirs(venv_t5, exist_ok = True)
-            r1 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "transformers==5.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
+        if not _ensure_venv_t5_exists():
+            raise RuntimeError(
+                f"Cannot activate transformers 5.x: .venv_t5 missing at {_VENV_T5_DIR}"
             )
-            r2 = sp.run(
-                [
-                    sys.executable,
-                    "-m",
-                    "pip",
-                    "install",
-                    "--target",
-                    venv_t5,
-                    "--no-deps",
-                    "huggingface_hub==1.3.0",
-                ],
-                stdout = sp.PIPE,
-                stderr = sp.STDOUT,
-            )
-            if r1.returncode != 0 or r2.returncode != 0:
-                raise RuntimeError(
-                    f"Failed to install transformers 5.x into {venv_t5}. "
-                    f"pip returncode: transformers={r1.returncode}, huggingface_hub={r2.returncode}"
-                )
-            sys.path.insert(0, venv_t5)
+        if _VENV_T5_DIR not in sys.path:
+            sys.path.insert(0, _VENV_T5_DIR)
+        logger.info("Activated transformers 5.x from %s", _VENV_T5_DIR)
         # Propagate to child subprocesses (e.g. GGUF converter)
         _pp = os.environ.get("PYTHONPATH", "")
-        os.environ["PYTHONPATH"] = venv_t5 + (os.pathsep + _pp if _pp else "")
+        os.environ["PYTHONPATH"] = _VENV_T5_DIR + (os.pathsep + _pp if _pp else "")
     else:
         logger.info("Using default transformers (4.57.x) for %s", model_name)
 

studio/backend/requirements/extras-no-deps.txt

@@ -11,4 +11,4 @@ git+https://github.com/meta-pytorch/OpenEnv.git
 # executorch>=1.0.1               # 41.5 MB - no imports in unsloth/zoo/studio
 torch-c-dlpack-ext
 sentence_transformers==5.2.0
-transformers==4.57.1
+transformers==4.57.6

studio/backend/requirements/single-env/constraints.txt

@@ -1,6 +1,6 @@
 # Single-env pins for unsloth + studio + data-designer
 # Keep compatible with unsloth transformers bounds.
-transformers==4.57.1
+transformers==4.57.6
 trl==0.23.1
 huggingface-hub==0.36.2
 

studio/backend/utils/transformers_version.py

@@ -26,6 +26,7 @@ import json
 import structlog
 from loggers import get_logger
 import os
+import shutil
 import subprocess
 import sys
 from pathlib import Path
@@ -58,7 +59,7 @@ _tokenizer_class_cache: dict[str, bool] = {}
 
 # Versions
 TRANSFORMERS_5_VERSION = "5.3.0"
-TRANSFORMERS_DEFAULT_VERSION = "4.57.1"
+TRANSFORMERS_DEFAULT_VERSION = "4.57.6"
 
 # Pre-installed directory for transformers 5.x — created by setup.sh / setup.ps1
 _VENV_T5_DIR = str(Path.home() / ".unsloth" / "studio" / ".venv_t5")
@@ -216,15 +217,55 @@ def _purge_modules() -> int:
     return len(to_remove)
 
 
-def _ensure_venv_t5_exists() -> bool:
-    """Ensure .venv_t5/ exists. Install at runtime if missing."""
-    if os.path.isdir(_VENV_T5_DIR) and os.listdir(_VENV_T5_DIR):
-        return True
+_VENV_T5_PACKAGES = (
+    f"transformers=={TRANSFORMERS_5_VERSION}",
+    "huggingface_hub==1.7.1",
+    "hf_xet==1.4.2",
+)
 
-    logger.warning(".venv_t5 not found at %s — installing at runtime", _VENV_T5_DIR)
-    os.makedirs(_VENV_T5_DIR, exist_ok = True)
-    for pkg in (f"transformers=={TRANSFORMERS_5_VERSION}", "huggingface_hub==1.3.0"):
-        cmd = [
+
+def _venv_t5_is_valid() -> bool:
+    """Return True if .venv_t5/ has all required packages installed."""
+    if not os.path.isdir(_VENV_T5_DIR) or not os.listdir(_VENV_T5_DIR):
+        return False
+    # Check that the key package directories actually exist
+    for pkg_spec in _VENV_T5_PACKAGES:
+        pkg_name = pkg_spec.split("==")[0].replace("-", "_")
+        if not any(
+            (Path(_VENV_T5_DIR) / d).is_dir()
+            for d in (pkg_name, pkg_name.replace("_", "-"))
+        ):
+            return False
+    return True
+
+
+def _install_to_venv_t5(pkg: str) -> bool:
+    """Install a single package into .venv_t5/, preferring uv then pip."""
+    # Try uv first (faster) if already on PATH -- do NOT install uv at runtime
+    if shutil.which("uv"):
+        result = subprocess.run(
+            [
+                "uv",
+                "pip",
+                "install",
+                "--python",
+                sys.executable,
+                "--target",
+                _VENV_T5_DIR,
+                "--no-deps",
+                pkg,
+            ],
+            stdout = subprocess.PIPE,
+            stderr = subprocess.STDOUT,
+            text = True,
+        )
+        if result.returncode == 0:
+            return True
+        logger.warning("uv install of %s failed, falling back to pip", pkg)
+
+    # Fallback to pip
+    result = subprocess.run(
+        [
             sys.executable,
             "-m",
             "pip",
@@ -233,12 +274,28 @@ def _ensure_venv_t5_exists() -> bool:
             _VENV_T5_DIR,
             "--no-deps",
             pkg,
-        ]
-        result = subprocess.run(
-            cmd, stdout = subprocess.PIPE, stderr = subprocess.STDOUT, text = True
-        )
-        if result.returncode != 0:
-            logger.error("pip install failed:\n%s", result.stdout)
+        ],
+        stdout = subprocess.PIPE,
+        stderr = subprocess.STDOUT,
+        text = True,
+    )
+    if result.returncode != 0:
+        logger.error("install failed:\n%s", result.stdout)
+        return False
+    return True
+
+
+def _ensure_venv_t5_exists() -> bool:
+    """Ensure .venv_t5/ exists with all required packages. Install if missing."""
+    if _venv_t5_is_valid():
+        return True
+
+    logger.warning(
+        ".venv_t5 not found or incomplete at %s -- installing at runtime", _VENV_T5_DIR
+    )
+    os.makedirs(_VENV_T5_DIR, exist_ok = True)
+    for pkg in _VENV_T5_PACKAGES:
+        if not _install_to_venv_t5(pkg):
             return False
     logger.info("Installed transformers 5.x to %s", _VENV_T5_DIR)
     return True

studio/install_python_stack.py

@@ -140,15 +140,15 @@ def _bootstrap_uv() -> bool:
     global UV_NEEDS_SYSTEM
     if not shutil.which("uv"):
         return False
-    # Probe: try a dry-run install without --system.
-    # If uv can't find a venv it exits with code 2.
+    # Probe: try a dry-run install targeting the current Python explicitly.
+    # Without --python, uv can ignore the activated venv on some platforms.
     probe = subprocess.run(
-        ["uv", "pip", "install", "--dry-run", "pip"],
+        ["uv", "pip", "install", "--dry-run", "--python", sys.executable, "pip"],
         stdout = subprocess.PIPE,
         stderr = subprocess.STDOUT,
     )
     if probe.returncode != 0:
-        # Retry with --system to confirm it works
+        # Retry with --system (some envs need it when uv can't find a venv)
         probe_sys = subprocess.run(
             ["uv", "pip", "install", "--dry-run", "--system", "pip"],
             stdout = subprocess.PIPE,
@@ -204,6 +204,10 @@ def _build_uv_cmd(args: tuple[str, ...]) -> list[str]:
     cmd = ["uv", "pip", "install"]
     if UV_NEEDS_SYSTEM:
         cmd.append("--system")
+    # Always pass --python so uv targets the correct environment.
+    # Without this, uv can ignore an activated venv and install into
+    # the system Python (observed on Colab and similar environments).
+    cmd.extend(["--python", sys.executable])
     cmd.extend(_translate_pip_args_for_uv(args))
     cmd.append("--torch-backend=auto")
     return cmd

studio/setup.ps1

@@ -748,9 +748,39 @@ Write-Host ""
 # ==========================================================================
 #  PHASE 2: Frontend build (skip if pip-installed -- already bundled)
 # ==========================================================================
+$DistDir = Join-Path $FrontendDir "dist"
+# Skip build if dist/ exists and no tracked input is newer than dist/.
+# Checks src/, public/, package.json, config files -- not just src/.
+$NeedFrontendBuild = $true
 if ($IsPipInstall) {
+    $NeedFrontendBuild = $false
     Write-Host "[OK] Running from pip install - frontend already bundled, skipping build" -ForegroundColor Green
-} else {
+} elseif (Test-Path $DistDir) {
+    $DistTime = (Get-Item $DistDir).LastWriteTime
+    $NewerFile = $null
+    # Check src/ and public/ recursively (probe paths directly, not via -Include)
+    foreach ($subDir in @("src", "public")) {
+        $subPath = Join-Path $FrontendDir $subDir
+        if (Test-Path $subPath) {
+            $NewerFile = Get-ChildItem -Path $subPath -Recurse -File -ErrorAction SilentlyContinue |
+                Where-Object { $_.LastWriteTime -gt $DistTime } | Select-Object -First 1
+            if ($NewerFile) { break }
+        }
+    }
+    # Also check ALL top-level files (package.json, index.html, bun.lock, configs, etc.)
+    if (-not $NewerFile) {
+        $NewerFile = Get-ChildItem -Path $FrontendDir -File -ErrorAction SilentlyContinue |
+            Where-Object { $_.LastWriteTime -gt $DistTime } |
+            Select-Object -First 1
+    }
+    if (-not $NewerFile) {
+        $NeedFrontendBuild = $false
+        Write-Host "[OK] Frontend already built and up to date -- skipping build" -ForegroundColor Green
+    } else {
+        Write-Host "[INFO] Frontend source changed since last build -- rebuilding..." -ForegroundColor Yellow
+    }
+}
+if ($NeedFrontendBuild -and -not $IsPipInstall) {
     Write-Host ""
     Write-Host "Building frontend..." -ForegroundColor Cyan
     # npm writes warnings to stderr; lower ErrorActionPreference so PS doesn't
@@ -758,9 +788,6 @@ if ($IsPipInstall) {
     $prevEAP_npm = $ErrorActionPreference
     $ErrorActionPreference = "Continue"
     Push-Location $FrontendDir
-    # Remove stale node_modules and package-lock.json to avoid version conflicts
-    if (Test-Path "node_modules") { Remove-Item -Recurse -Force "node_modules" }
-    if (Test-Path "package-lock.json") { Remove-Item -Force "package-lock.json" }
     npm install 2>&1 | Out-Null
     if ($LASTEXITCODE -ne 0) {
         Pop-Location
@@ -845,7 +872,35 @@ $ErrorActionPreference = "Continue"
 
 $ActivateScript = Join-Path $VenvDir "Scripts\Activate.ps1"
 . $ActivateScript
-pip install --upgrade pip 2>&1 | Out-Null
+
+# Try to use uv (much faster than pip), fall back to pip if unavailable
+$UseUv = $false
+if (Get-Command uv -ErrorAction SilentlyContinue) {
+    $UseUv = $true
+} else {
+    Write-Host "   Installing uv package manager..." -ForegroundColor Cyan
+    try {
+        powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex" 2>&1 | Out-Null
+        Refresh-Environment
+        # Re-activate venv since Refresh-Environment rebuilds PATH from
+        # registry and drops the venv's Scripts directory
+        . $ActivateScript
+        if (Get-Command uv -ErrorAction SilentlyContinue) { $UseUv = $true }
+    } catch { }
+}
+
+# Helper: install a package, preferring uv with pip fallback
+function Fast-Install {
+    param([Parameter(ValueFromRemainingArguments=$true)]$Args_)
+    if ($UseUv) {
+        $VenvPy = (Get-Command python).Source
+        $result = & uv pip install --python $VenvPy @Args_ 2>&1
+        if ($LASTEXITCODE -eq 0) { return }
+    }
+    & python -m pip install @Args_ 2>&1
+}
+
+Fast-Install --upgrade pip | Out-Null
 
 # if (-not $IsPipInstall) {
 #     # Running from repo: copy requirements and do editable install
@@ -882,14 +937,14 @@ Write-Host "[OK] TORCHINDUCTOR_CACHE_DIR set to $TorchCacheDir (avoids MAX_PATH
 
 $CuTag = Get-PytorchCudaTag
 Write-Host "   Installing PyTorch with CUDA support ($CuTag)..." -ForegroundColor Cyan
-pip install torch torchvision torchaudio --index-url "https://download.pytorch.org/whl/$CuTag" 2>&1 | Out-Null
+Fast-Install torch torchvision torchaudio --index-url "https://download.pytorch.org/whl/$CuTag" | Out-Null
 
-# Install Triton for Windows (enables torch.compile — without it training can hang)
+# Install Triton for Windows (enables torch.compile -- without it training can hang)
 Write-Host "   Installing Triton for Windows..." -ForegroundColor Cyan
-pip install "triton-windows<3.7" 2>&1 | Out-Null
+Fast-Install "triton-windows<3.7" | Out-Null
 Write-Host "[OK] Triton for Windows installed (enables torch.compile)" -ForegroundColor Green
 
-# Ordered heavy dependency installation — shared cross-platform script
+# Ordered heavy dependency installation -- shared cross-platform script
 Write-Host "   Running ordered dependency installation..." -ForegroundColor Cyan
 python "$PSScriptRoot\install_python_stack.py"
 # Restore ErrorActionPreference after pip/python work
@@ -898,7 +953,7 @@ $ErrorActionPreference = $prevEAP
 # ── Pre-install transformers 5.x into .venv_t5/ ──
 # Models like GLM-4.7-Flash need transformers>=5.3.0. Instead of pip-installing
 # at runtime (slow, ~10-15s), we pre-install into a separate directory.
-# The training subprocess just prepends .venv_t5/ to sys.path — instant switch.
+# The training subprocess just prepends .venv_t5/ to sys.path -- instant switch.
 Write-Host ""
 Write-Host "   Pre-installing transformers 5.x for newer model support..." -ForegroundColor Cyan
 $VenvT5Dir = Join-Path $env:USERPROFILE ".unsloth\studio\.venv_t5"
@@ -906,17 +961,13 @@ if (Test-Path $VenvT5Dir) { Remove-Item -Recurse -Force $VenvT5Dir }
 New-Item -ItemType Directory -Path $VenvT5Dir -Force | Out-Null
 $prevEAP_t5 = $ErrorActionPreference
 $ErrorActionPreference = "Continue"
-pip install --target $VenvT5Dir --no-deps "transformers==5.3.0" 2>&1 | Out-Null
-if ($LASTEXITCODE -ne 0) {
-    Write-Host "[FAIL] Could not install transformers 5.3.0 into .venv_t5/" -ForegroundColor Red
-    $ErrorActionPreference = $prevEAP_t5
-    exit 1
-}
-pip install --target $VenvT5Dir --no-deps "huggingface_hub==1.3.0" 2>&1 | Out-Null
-if ($LASTEXITCODE -ne 0) {
-    Write-Host "[FAIL] Could not install huggingface_hub 1.3.0 into .venv_t5/" -ForegroundColor Red
-    $ErrorActionPreference = $prevEAP_t5
-    exit 1
+foreach ($pkg in @("transformers==5.3.0", "huggingface_hub==1.7.1", "hf_xet==1.4.2")) {
+    Fast-Install --target $VenvT5Dir --no-deps $pkg | Out-Null
+    if ($LASTEXITCODE -ne 0) {
+        Write-Host "[FAIL] Could not install $pkg into .venv_t5/" -ForegroundColor Red
+        $ErrorActionPreference = $prevEAP_t5
+        exit 1
+    }
 }
 $ErrorActionPreference = $prevEAP_t5
 Write-Host "[OK] Transformers 5.x pre-installed to .venv_t5/" -ForegroundColor Green

studio/setup.sh

@@ -41,13 +41,25 @@ if [[ "$keynames" == *$'\nCOLAB_'* ]]; then
 fi
 
 # ── Detect whether frontend needs building ──
-# Only skip when BOTH conditions are true:
-#   1. We're inside site-packages (PyPI / pip install, not editable)
-#   2. dist/ already exists (pre-built in the wheel)
-# Otherwise always (re)build — handles upgrades, editable installs, and
-# pip-from-source where dist/ was never built.
-if [[ "$SCRIPT_DIR" == */site-packages/* ]] && [ -d "$SCRIPT_DIR/frontend/dist" ]; then
-    echo "✅ Frontend pre-built (PyPI) — skipping Node/npm check."
+# Skip if dist/ exists AND no tracked input is newer than dist/.
+# Checks src/, public/, package.json, config files -- not just src/.
+# This handles: PyPI installs (dist/ bundled), repeat runs (no changes),
+# and upgrades/pulls (source newer than dist/ triggers rebuild).
+_NEED_FRONTEND_BUILD=true
+if [ -d "$SCRIPT_DIR/frontend/dist" ]; then
+    # Check top-level config files (package.json, vite.config.ts, index.html, bun.lock, etc.)
+    _changed=$(find "$SCRIPT_DIR/frontend" -maxdepth 1 -type f -newer "$SCRIPT_DIR/frontend/dist" 2>/dev/null | head -1)
+    # Check src/ and public/ recursively
+    if [ -z "$_changed" ]; then
+        _changed=$(find "$SCRIPT_DIR/frontend/src" "$SCRIPT_DIR/frontend/public" \
+            -type f -newer "$SCRIPT_DIR/frontend/dist" 2>/dev/null | head -1)
+    fi
+    if [ -z "$_changed" ]; then
+        _NEED_FRONTEND_BUILD=false
+    fi
+fi
+if [ "$_NEED_FRONTEND_BUILD" = false ]; then
+    echo "✅ Frontend already built and up to date -- skipping Node/npm check."
 else
 NEED_NODE=true
 if command -v node &>/dev/null && command -v npm &>/dev/null; then
@@ -146,12 +158,17 @@ run_quiet "npm run build" npm run build
 
 _restore_gitignores
 trap - EXIT
-cd "$SCRIPT_DIR/backend/core/data_recipe/oxc-validator"
-run_quiet "npm install (oxc validator runtime)" npm install
 cd "$SCRIPT_DIR"
 echo "✅ Frontend built to frontend/dist"
 
-fi  # end frontend dist check
+fi  # end frontend build check
+
+# ── oxc-validator runtime (needs npm -- skip if not available) ──
+if [ -d "$SCRIPT_DIR/backend/core/data_recipe/oxc-validator" ] && command -v npm &>/dev/null; then
+    cd "$SCRIPT_DIR/backend/core/data_recipe/oxc-validator"
+    run_quiet "npm install (oxc validator runtime)" npm install
+    cd "$SCRIPT_DIR"
+fi
 
 # ── 6. Python venv + deps ──
 
@@ -223,50 +240,73 @@ install_python_stack() {
     python "$SCRIPT_DIR/install_python_stack.py"
 }
 
-if [ "$IS_COLAB" = true ]; then
-    # Colab: install packages directly without venv
-    install_python_stack
-else
-    # Local: create venv under ~/.unsloth/studio/ (shared location, not in repo)
-    STUDIO_HOME="$HOME/.unsloth/studio"
-    VENV_DIR="$STUDIO_HOME/.venv"
-    VENV_T5_DIR="$STUDIO_HOME/.venv_t5"
-    mkdir -p "$STUDIO_HOME"
+# Create venv under ~/.unsloth/studio/ (shared location, not in repo).
+# All platforms (including Colab) use the same isolated venv so that
+# studio dependencies are never installed into the system Python.
+STUDIO_HOME="$HOME/.unsloth/studio"
+VENV_DIR="$STUDIO_HOME/.venv"
+VENV_T5_DIR="$STUDIO_HOME/.venv_t5"
+mkdir -p "$STUDIO_HOME"
 
-    # Clean up legacy in-repo venvs if they exist
-    [ -d "$REPO_ROOT/.venv" ] && rm -rf "$REPO_ROOT/.venv"
-    [ -d "$REPO_ROOT/.venv_overlay" ] && rm -rf "$REPO_ROOT/.venv_overlay"
-    [ -d "$REPO_ROOT/.venv_t5" ] && rm -rf "$REPO_ROOT/.venv_t5"
+# Clean up legacy in-repo venvs if they exist
+[ -d "$REPO_ROOT/.venv" ] && rm -rf "$REPO_ROOT/.venv"
+[ -d "$REPO_ROOT/.venv_overlay" ] && rm -rf "$REPO_ROOT/.venv_overlay"
+[ -d "$REPO_ROOT/.venv_t5" ] && rm -rf "$REPO_ROOT/.venv_t5"
 
-    rm -rf "$VENV_DIR"
-    rm -rf "$VENV_T5_DIR"
-    "$BEST_PY" -m venv "$VENV_DIR"
+rm -rf "$VENV_DIR"
+rm -rf "$VENV_T5_DIR"
+# Try creating venv with pip; fall back to --without-pip + bootstrap
+# (some environments like Colab have broken ensurepip)
+if ! "$BEST_PY" -m venv "$VENV_DIR" 2>/dev/null; then
+    "$BEST_PY" -m venv --without-pip "$VENV_DIR"
     source "$VENV_DIR/bin/activate"
-    cd "$SCRIPT_DIR"
-    install_python_stack
+    curl -sS https://bootstrap.pypa.io/get-pip.py | python > /dev/null
+else
+    source "$VENV_DIR/bin/activate"
+fi
 
-    # ── 6b. Pre-install transformers 5.x into .venv_t5/ ──
-    # Models like GLM-4.7-Flash need transformers>=5.3.0. Instead of pip-installing
-    # at runtime (slow, ~10-15s), we pre-install into a separate directory.
-    # The training subprocess just prepends .venv_t5/ to sys.path — instant switch.
-    echo ""
-    echo "   Pre-installing transformers 5.x for newer model support..."
-    mkdir -p "$VENV_T5_DIR"
-    run_quiet "pip install transformers 5.x" pip install --target "$VENV_T5_DIR" --no-deps "transformers==5.3.0"
-    run_quiet "pip install huggingface_hub for t5" pip install --target "$VENV_T5_DIR" --no-deps "huggingface_hub==1.3.0"
-    echo "✅ Transformers 5.x pre-installed to $VENV_T5_DIR/"
+# ── Ensure uv is available (much faster than pip) ──
+USE_UV=false
+if command -v uv &>/dev/null; then
+    USE_UV=true
+elif curl -LsSf https://astral.sh/uv/install.sh | sh > /dev/null 2>&1; then
+    export PATH="$HOME/.local/bin:$PATH"
+    command -v uv &>/dev/null && USE_UV=true
+fi
 
-    # ── 7. WSL: pre-install GGUF build dependencies ──
-    # On WSL, sudo requires a password and can't be entered during GGUF export
-    # (runs in a non-interactive subprocess). Install build deps here instead.
-    if grep -qi microsoft /proc/version 2>/dev/null; then
-        echo ""
-        echo "⚠️  WSL detected — installing build dependencies for GGUF export..."
-        echo "   You may be prompted for your password."
-        sudo apt-get update -y
-        sudo apt-get install -y build-essential cmake curl git libcurl4-openssl-dev
-        echo "✅ GGUF build dependencies installed"
+# Helper: install a package, preferring uv with pip fallback
+fast_install() {
+    if [ "$USE_UV" = true ]; then
+        uv pip install --python "$(command -v python)" "$@" && return 0
     fi
+    python -m pip install "$@"
+}
+
+cd "$SCRIPT_DIR"
+install_python_stack
+
+# ── 6b. Pre-install transformers 5.x into .venv_t5/ ──
+# Models like GLM-4.7-Flash need transformers>=5.3.0. Instead of pip-installing
+# at runtime (slow, ~10-15s), we pre-install into a separate directory.
+# The training subprocess just prepends .venv_t5/ to sys.path -- instant switch.
+echo ""
+echo "   Pre-installing transformers 5.x for newer model support..."
+mkdir -p "$VENV_T5_DIR"
+run_quiet "install transformers 5.x" fast_install --target "$VENV_T5_DIR" --no-deps "transformers==5.3.0"
+run_quiet "install huggingface_hub for t5" fast_install --target "$VENV_T5_DIR" --no-deps "huggingface_hub==1.7.1"
+run_quiet "install hf_xet for t5" fast_install --target "$VENV_T5_DIR" --no-deps "hf_xet==1.4.2"
+echo "✅ Transformers 5.x pre-installed to $VENV_T5_DIR/"
+
+# ── 7. WSL: pre-install GGUF build dependencies ──
+# On WSL, sudo requires a password and can't be entered during GGUF export
+# (runs in a non-interactive subprocess). Install build deps here instead.
+if grep -qi microsoft /proc/version 2>/dev/null; then
+    echo ""
+    echo "⚠️  WSL detected -- installing build dependencies for GGUF export..."
+    echo "   You may be prompted for your password."
+    sudo apt-get update -y
+    sudo apt-get install -y build-essential cmake curl git libcurl4-openssl-dev
+    echo "✅ GGUF build dependencies installed"
 fi
 
 # ── 8. Build llama.cpp binaries for GGUF inference + export ──
@@ -405,6 +445,9 @@ if [ "$IS_COLAB" = true ]; then
     echo "╠══════════════════════════════════════╣"
     echo "║ Unsloth Studio is ready to start     ║"
     echo "║ in your Colab notebook!              ║"
+    echo "║                                      ║"
+    echo "║ from colab import start              ║"
+    echo "║ start()                              ║"
     echo "╚══════════════════════════════════════╝"
 else
     echo "╔══════════════════════════════════════╗"