constrain torch version

.github/workflows/tests.yml

@@ -83,7 +83,8 @@ jobs:
         run: |
           uv pip show --system torch
           uv pip install --system wheel
-          uv pip install --system --no-build-isolation -e ".[dev]"
+          printf "torch==${{ matrix.pytorch_version }}\n" > torch-constraints.txt
+          uv pip install --system --no-build-isolation -e ".[dev]" --constraints torch-constraints.txt
           set -o pipefail
           python scripts/unsloth_install.py | bash
           python scripts/cutcrossentropy_install.py | bash
@@ -160,7 +161,8 @@ jobs:
           uv pip install --system dist/*.tar.gz
           python scripts/unsloth_install.py | sh
           python scripts/cutcrossentropy_install.py | sh
-          uv pip install --system ".[dev]"
+          printf "torch==${{ matrix.pytorch_version }}\n" > torch-constraints.txt
+          uv pip install --system ".[dev]" --constraints torch-constraints.txt
 
       - name: Make sure PyTorch version wasn't clobbered
         run: |

scripts/unsloth_install.py

@@ -1,6 +1,23 @@
-"""Print the uv commands required to install Unsloth."""
+"""Print the uv commands required to install Unsloth without altering Torch."""
 
-UNSLOTH_BASE = "uv pip install --system unsloth-zoo==2025.9.12"
-UNSLOTH_HF = 'uv pip install --system --no-deps "unsloth[huggingface]==2025.9.9"'
+try:
+    import torch
+except ImportError as error:
+    raise ImportError("Install torch via `pip install torch`") from error
 
-print(f"{UNSLOTH_BASE} && {UNSLOTH_HF}")
+from packaging.version import Version as V
+
+TORCH_MIN = V("2.6.0")
+UNSLOTH_BASE = (
+    "uv pip install --system --no-deps unsloth-zoo==2025.9.12"
+    ' && uv pip install --system --no-deps "unsloth[huggingface]==2025.9.9"'
+)
+
+version = V(torch.__version__)
+if version < TORCH_MIN:
+    raise RuntimeError(
+        f"Torch {version} detected, but Unsloth requires >= {TORCH_MIN}. "
+        "Upgrade your torch install and re-run this helper."
+    )
+
+print(UNSLOTH_BASE)