From 817f31345fb345adad0188b98e5ea1332346267f Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 17:13:53 +0530
Subject: [PATCH 01/23] add e2e tests for kernel builder cli.

---
 .github/workflows/test_e2e.yaml | 176 +++++++++++++
 e2e-test-plan.md                | 435 ++++++++++++++++++++++++++++++++
 2 files changed, 611 insertions(+)
 create mode 100644 .github/workflows/test_e2e.yaml
 create mode 100644 e2e-test-plan.md

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
new file mode 100644
index 00000000..21d1a108
--- /dev/null
+++ b/.github/workflows/test_e2e.yaml
@@ -0,0 +1,176 @@
+name: "E2E: kernel-builder init + build + upload + download"
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+    paths:
+      - "kernel-builder/**"
+      - "kernels/src/**"
+      - "nix-builder/**"
+      - "kernels-data/**"
+      - ".github/workflows/test_e2e.yaml"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  init-and-build:
+    name: Init and build kernel
+    runs-on:
+      group: aws-highmemory-32-plus-nix
+    steps:
+      - uses: actions/checkout@v6
+      - uses: DeterminateSystems/nix-installer-action@main
+        with:
+          extra-conf: |
+            max-jobs = 8
+            cores = 12
+            sandbox-fallback = false
+      - uses: cachix/cachix-action@v16
+        with:
+          name: huggingface
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+        env:
+          USER: runner
+
+      - name: Build kernel-builder CLI
+        run: cargo build --release --manifest-path kernel-builder/Cargo.toml
+
+      - name: Init kernel project
+        run: |
+          cd /tmp
+          $GITHUB_WORKSPACE/target/release/kernel-builder init \
+            --name kernels-test/e2e-test-kernel \
+            --backends cuda
+
+      - name: Validate scaffold
+        run: |
+          cd /tmp/e2e-test-kernel
+          test -f build.toml
+          test -f flake.nix
+          test -f torch-ext/e2e_test_kernel/__init__.py
+          test -f torch-ext/torch_binding.cpp
+          test -f torch-ext/torch_binding.h
+          test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
+          test -f tests/test_e2e_test_kernel.py
+          test -f example.py
+          grep -q 'name = "e2e-test-kernel"' build.toml
+          grep -q 'repo-id = "kernels-test/e2e-test-kernel"' build.toml
+          grep -q 'backend = "cuda"' build.toml
+
+      - name: Patch flake.nix to use local nix-builder
+        run: |
+          cd /tmp/e2e-test-kernel
+          sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
+
+      - name: Build one CUDA variant
+        run: |
+          cd /tmp/e2e-test-kernel
+          nix build .#ci -L
+          mkdir -p build
+          cp -rL result/* build/
+
+      - name: Verify build artifacts
+        run: |
+          cd /tmp/e2e-test-kernel
+          VARIANT_DIR=$(ls -d build/torch* | head -1)
+          echo "Built variant: $VARIANT_DIR"
+          test -f "$VARIANT_DIR/__init__.py"
+          test -f "$VARIANT_DIR/metadata.json"
+          ls "$VARIANT_DIR"/*.so
+
+      - name: Upload built kernel
+        uses: actions/upload-artifact@v6
+        with:
+          name: e2e-built-kernel
+          path: /tmp/e2e-test-kernel/
+
+      - name: Upload kernel-builder binary
+        uses: actions/upload-artifact@v6
+        with:
+          name: kernel-builder-bin
+          path: ${{ github.workspace }}/target/release/kernel-builder
+
+  upload:
+    name: Upload kernel to Hub
+    needs: init-and-build
+    runs-on:
+      group: aws-g6-12xlarge-plus
+    env:
+      HF_TOKEN: ${{ secrets.HF_TOKEN }}
+    steps:
+      - name: Download built kernel
+        uses: actions/download-artifact@v7
+        with:
+          name: e2e-built-kernel
+          path: /tmp/e2e-test-kernel
+
+      - name: Download kernel-builder binary
+        uses: actions/download-artifact@v7
+        with:
+          name: kernel-builder-bin
+          path: /tmp/bin
+
+      - name: Make binary executable
+        run: chmod +x /tmp/bin/kernel-builder
+
+      - name: Upload kernel to Hub
+        run: |
+          /tmp/bin/kernel-builder upload /tmp/e2e-test-kernel \
+            --repo-id kernels-test/kernels-upload-test
+
+  download-and-test:
+    name: Download and test kernel via get_kernel
+    needs: upload
+    runs-on:
+      group: aws-g6-12xlarge-plus
+    env:
+      HF_TOKEN: ${{ secrets.HF_TOKEN }}
+      UV_PYTHON_PREFERENCE: only-managed
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install uv and set Python version
+        uses: astral-sh/setup-uv@v7
+        with:
+          python-version: "3.12"
+
+      - name: Install Python deps
+        working-directory: ./kernels
+        run: |
+          uv sync --all-extras --dev
+          uv pip install torch==2.10.0
+
+      - name: Test get_kernel download and usage
+        working-directory: ./kernels
+        run: |
+          uv run python -c "
+          import torch
+          from kernels import get_kernel
+
+          kernel = get_kernel('kernels-test/kernels-upload-test', version=1)
+
+          x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
+          result = kernel.e2e_test_kernel(x)
+          expected = x + 1.0
+          torch.testing.assert_close(result, expected)
+          print('E2E test passed: get_kernel + correctness check')
+          "
+
+      - name: Cleanup Hub repo
+        if: always()
+        working-directory: ./kernels
+        run: |
+          uv run python -c "
+          from huggingface_hub import HfApi
+          api = HfApi()
+          try:
+              api.delete_repo('kernels-test/kernels-upload-test')
+              print('Cleaned up repo')
+          except Exception as e:
+              print(f'Cleanup warning: {e}')
+          "
diff --git a/e2e-test-plan.md b/e2e-test-plan.md
new file mode 100644
index 00000000..dfc83fda
--- /dev/null
+++ b/e2e-test-plan.md
@@ -0,0 +1,435 @@
+# E2E Test Plan: kernel-builder init + build + upload + get_kernel
+
+## Goal
+
+Validate the full lifecycle: `kernel-builder init` creates a valid project, the template builds successfully, the built kernel can be uploaded to the Hub, and `get_kernel()` can download and use it.
+
+---
+
+## Overview
+
+A single GitHub Actions workflow with three jobs for fault isolation:
+
+1. **init-and-build** (Nix runner) -- `kernel-builder init`, validate scaffold, `nix build` one CUDA variant.
+2. **upload** (GPU runner) -- `kernel-builder upload` the built artifacts to Hub.
+3. **download-and-test** (GPU runner) -- `get_kernel()` download + correctness check, cleanup.
+
+If init+build fails, we know the template or build infra is broken. If upload fails, the Rust upload logic is broken. If download+test fails, the Python `get_kernel()` path is broken. Each job's failure points to a specific component.
+
+---
+
+## Speed considerations
+
+- **Build exactly one variant.** Use the `ci` Nix target which selects one variant per framework (one CUDA variant in our case).
+- **No matrix.** Single Python version (3.12), single Torch version (latest: 2.10), single backend (CUDA).
+- **Cachix.** Leverage the existing `huggingface` Cachix cache so Nix derivations are fetched, not rebuilt.
+- **Compile `kernel-builder` with `--release` once** in the build job and pass the binary via artifact to the GPU jobs (avoids compiling Rust twice).
+
+---
+
+## Trigger paths
+
+The workflow should run on changes to the core components that affect this lifecycle:
+
+```yaml
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+    paths:
+      - "kernel-builder/**"      # CLI: init, build, upload commands
+      - "kernels/src/**"         # Python library: get_kernel, variants, install
+      - "nix-builder/**"         # Nix build infrastructure
+      - "kernels-data/**"        # Shared config/data structures
+  workflow_dispatch:
+```
+
+This keeps the e2e tests focused on changes that could actually break the init/build/upload/download cycle, avoiding unnecessary runs on docs-only or CI config changes.
+
+---
+
+## Job 1: `init-and-build`
+
+### What it validates
+
+- `kernel-builder init` produces a complete, well-formed project.
+- The generated `build.toml` is valid.
+- The project builds via Nix without errors.
+- The build produces a working kernel variant.
+
+### Implementation
+
+**Runner:** `aws-highmemory-32-plus-nix` (matches existing `build_kernel.yaml`)
+
+#### Step 1: Build `kernel-builder` CLI
+
+```bash
+cargo build --release --manifest-path kernel-builder/Cargo.toml
+```
+
+#### Step 2: Init a fresh kernel project
+
+```bash
+cd /tmp
+kernel-builder init --name kernels-test/e2e-test-kernel --backends cuda
+```
+
+Creates `/tmp/e2e-test-kernel/` with the full scaffold.
+
+#### Step 3: Validate the scaffold
+
+Quick checks that key files exist:
+
+```bash
+cd /tmp/e2e-test-kernel
+test -f build.toml
+test -f flake.nix
+test -f torch-ext/e2e_test_kernel/__init__.py
+test -f torch-ext/torch_binding.cpp
+test -f torch-ext/torch_binding.h
+test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
+test -f tests/test_e2e_test_kernel.py
+test -f example.py
+```
+
+Verify key fields in `build.toml`:
+- `name = "e2e-test-kernel"`
+- `repo-id = "kernels-test/e2e-test-kernel"`
+- `backend = "cuda"` appears in a kernel section
+
+#### Step 4: Patch flake.nix for local nix-builder
+
+The init template generates a `flake.nix` that references `github:huggingface/kernels` (the remote repo). For CI, we need it to use the **local checkout** so the test validates the current code:
+
+```bash
+cd /tmp/e2e-test-kernel
+sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
+```
+
+This changes `kernel-builder.url = "github:huggingface/kernels"` to `kernel-builder.url = "path:/path/to/checkout"`, matching how the example kernels work (`path:../../..`).
+
+#### Step 5: Build one CUDA variant with Nix
+
+```bash
+cd /tmp/e2e-test-kernel
+nix build .#ci -L
+cp -rL result/* build/
+```
+
+The `ci` Nix target builds exactly one variant per framework. This is the fastest path -- it's the same target the existing `build_kernel.yaml` CI uses.
+
+#### Step 6: Verify build artifacts
+
+```bash
+VARIANT_DIR=$(ls -d build/torch* | head -1)
+test -f "$VARIANT_DIR/__init__.py"
+test -f "$VARIANT_DIR/metadata.json"
+ls "$VARIANT_DIR"/*.so  # At least one shared object
+```
+
+#### Step 7: Upload artifacts
+
+Upload the built kernel directory and `kernel-builder` binary for downstream jobs.
+
+---
+
+## Job 2: `upload`
+
+### What it validates
+
+- `kernel-builder upload` successfully pushes build artifacts to a Hub repo.
+
+### Implementation
+
+**Runner:** `aws-g6-12xlarge-plus` (GPU runner -- needed for Job 3 anyway, reuse the same runner group)
+**Depends on:** `init-and-build`
+
+#### Step 1: Download artifacts from Job 1
+
+Download the built kernel directory and `kernel-builder` binary.
+
+#### Step 2: Upload kernel to Hub
+
+```bash
+kernel-builder upload /tmp/e2e-test-kernel \
+  --repo-id kernels-test/kernels-upload-test \
+  --private
+```
+
+Uses `HF_TOKEN` secret for authentication.
+
+---
+
+## Job 3: `download-and-test`
+
+### What it validates
+
+- `get_kernel()` can download the uploaded kernel and resolve the correct variant.
+- The imported module is callable and produces correct results.
+
+### Implementation
+
+**Runner:** `aws-g6-12xlarge-plus` (GPU runner)
+**Depends on:** `upload`
+
+#### Step 1: Install Python deps
+
+```bash
+cd kernels
+uv sync --all-extras --dev
+uv pip install torch==2.10.0
+```
+
+#### Step 2: Download and test via `get_kernel()`
+
+```python
+import torch
+from kernels import get_kernel
+
+kernel = get_kernel("kernels-test/kernels-upload-test", version=1)
+
+x = torch.randn(1024, 1024, dtype=torch.float32, device="cuda")
+result = kernel.e2e_test_kernel(x)
+expected = x + 1.0
+torch.testing.assert_close(result, expected)
+print("E2E test passed!")
+```
+
+#### Step 3: Cleanup (always runs)
+
+Delete the Hub repo regardless of test outcome:
+
+```python
+from huggingface_hub import HfApi
+api = HfApi()
+api.delete_repo("kernels-test/kernels-upload-test")
+```
+
+---
+
+## Key risks and mitigations
+
+| Risk | Mitigation |
+|------|------------|
+| Init template `flake.nix` points to remote nix-builder | `sed` patch to use `path:$GITHUB_WORKSPACE` |
+| Leftover repos on failure | `if: always()` cleanup step in Job 3 |
+| Nix build is slow | Use `ci` target (one variant) + Cachix caching |
+| Rust recompilation on GPU runner | Pass pre-built binary via artifact |
+
+---
+
+## Complete workflow file
+
+```yaml
+name: "E2E: kernel-builder init + build + upload + download"
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+    paths:
+      - "kernel-builder/**"
+      - "kernels/src/**"
+      - "nix-builder/**"
+      - "kernels-data/**"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  init-and-build:
+    name: Init and build kernel
+    runs-on:
+      group: aws-highmemory-32-plus-nix
+    steps:
+      - uses: actions/checkout@v6
+      - uses: DeterminateSystems/nix-installer-action@main
+        with:
+          extra-conf: |
+            max-jobs = 8
+            cores = 12
+            sandbox-fallback = false
+      - uses: cachix/cachix-action@v16
+        with:
+          name: huggingface
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+        env:
+          USER: runner
+
+      - name: Build kernel-builder CLI
+        run: cargo build --release --manifest-path kernel-builder/Cargo.toml
+
+      - name: Init kernel project
+        run: |
+          cd /tmp
+          $GITHUB_WORKSPACE/target/release/kernel-builder init \
+            --name kernels-test/e2e-test-kernel \
+            --backends cuda
+
+      - name: Validate scaffold
+        run: |
+          cd /tmp/e2e-test-kernel
+          test -f build.toml
+          test -f flake.nix
+          test -f torch-ext/e2e_test_kernel/__init__.py
+          test -f torch-ext/torch_binding.cpp
+          test -f torch-ext/torch_binding.h
+          test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
+          test -f tests/test_e2e_test_kernel.py
+          test -f example.py
+          grep -q 'name = "e2e-test-kernel"' build.toml
+          grep -q 'repo-id = "kernels-test/e2e-test-kernel"' build.toml
+          grep -q 'backend = "cuda"' build.toml
+
+      - name: Patch flake.nix to use local nix-builder
+        run: |
+          cd /tmp/e2e-test-kernel
+          sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
+
+      - name: Build one CUDA variant
+        run: |
+          cd /tmp/e2e-test-kernel
+          nix build .#ci -L
+          mkdir -p build
+          cp -rL result/* build/
+
+      - name: Verify build artifacts
+        run: |
+          cd /tmp/e2e-test-kernel
+          VARIANT_DIR=$(ls -d build/torch* | head -1)
+          echo "Built variant: $VARIANT_DIR"
+          test -f "$VARIANT_DIR/__init__.py"
+          test -f "$VARIANT_DIR/metadata.json"
+          ls "$VARIANT_DIR"/*.so
+
+      - name: Upload built kernel
+        uses: actions/upload-artifact@v6
+        with:
+          name: e2e-built-kernel
+          path: /tmp/e2e-test-kernel/
+
+      - name: Upload kernel-builder binary
+        uses: actions/upload-artifact@v6
+        with:
+          name: kernel-builder-bin
+          path: ${{ github.workspace }}/target/release/kernel-builder
+
+  upload:
+    name: Upload kernel to Hub
+    needs: init-and-build
+    runs-on:
+      group: aws-g6-12xlarge-plus
+    env:
+      HF_TOKEN: ${{ secrets.HF_TOKEN }}
+    steps:
+      - name: Download built kernel
+        uses: actions/download-artifact@v7
+        with:
+          name: e2e-built-kernel
+          path: /tmp/e2e-test-kernel
+
+      - name: Download kernel-builder binary
+        uses: actions/download-artifact@v7
+        with:
+          name: kernel-builder-bin
+          path: /tmp/bin
+
+      - name: Make binary executable
+        run: chmod +x /tmp/bin/kernel-builder
+
+      - name: Upload kernel to Hub
+        run: |
+          /tmp/bin/kernel-builder upload /tmp/e2e-test-kernel \
+            --repo-id kernels-test/kernels-upload-test \
+
+  download-and-test:
+    name: Download and test kernel via get_kernel
+    needs: upload
+    runs-on:
+      group: aws-g6-12xlarge-plus
+    env:
+      HF_TOKEN: ${{ secrets.HF_TOKEN }}
+      UV_PYTHON_PREFERENCE: only-managed
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Install uv and set Python version
+        uses: astral-sh/setup-uv@v7
+        with:
+          python-version: "3.12"
+
+      - name: Install Python deps
+        working-directory: ./kernels
+        run: |
+          uv sync --all-extras --dev
+          uv pip install torch==2.10.0
+
+      - name: Test get_kernel download and usage
+        working-directory: ./kernels
+        run: |
+          uv run python -c "
+          import torch
+          from kernels import get_kernel
+
+          kernel = get_kernel('kernels-test/kernels-upload-test', version=1)
+
+          x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
+          result = kernel.e2e_test_kernel(x)
+          expected = x + 1.0
+          torch.testing.assert_close(result, expected)
+          print('E2E test passed: get_kernel + correctness check')
+          "
+
+      - name: Cleanup Hub repo
+        if: always()
+        working-directory: ./kernels
+        run: |
+          uv run python -c "
+          from huggingface_hub import HfApi
+          api = HfApi()
+          try:
+              api.delete_repo('kernels-test/kernels-upload-test')
+              print('Cleaned up repo')
+          except Exception as e:
+              print(f'Cleanup warning: {e}')
+          "
+```
+
+---
+
+## Files to create
+
+| File | Purpose |
+|------|---------|
+| `.github/workflows/test_e2e.yaml` | The workflow above |
+
+No new Python test files needed -- the e2e test is self-contained in the workflow.
+
+---
+
+## Execution flow
+
+```
+Job 1: init-and-build (Nix runner, no GPU)
+  1. cargo build kernel-builder
+  2. kernel-builder init --backends cuda
+  3. validate scaffold files + build.toml
+  4. patch flake.nix → local nix-builder
+  5. nix build .#ci (one CUDA variant)
+  6. verify artifacts (*.so, metadata.json)
+  → artifacts: built kernel dir + kernel-builder binary
+
+Job 2: upload (GPU runner)
+  7. kernel-builder upload → Hub
+  ✗ Failure here = upload logic is broken
+
+Job 3: download-and-test (GPU runner)
+  8. get_kernel() → download + import
+  9. call kernel function + assert correctness
+  10. delete Hub repo (always)
+  ✗ Failure here = Python get_kernel / variant resolution is broken
+```

From 14a258abdccf911e624ed127ac7bc7cbca6b74ac Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 17:31:58 +0530
Subject: [PATCH 02/23] fix more.

---
 .github/workflows/test_e2e.yaml | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 21d1a108..7795289a 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -20,6 +20,8 @@ concurrency:
 jobs:
   init-and-build:
     name: Init and build kernel
+    outputs:
+      torch_version: ${{ steps.detect-variant.outputs.torch_version }}
     runs-on:
       group: aws-highmemory-32-plus-nix
     steps:
@@ -74,7 +76,8 @@ jobs:
           mkdir -p build
           cp -rL result/* build/
 
-      - name: Verify build artifacts
+      - name: Verify build artifacts and detect Torch version
+        id: detect-variant
         run: |
           cd /tmp/e2e-test-kernel
           VARIANT_DIR=$(ls -d build/torch* | head -1)
@@ -83,6 +86,15 @@ jobs:
           test -f "$VARIANT_DIR/metadata.json"
           ls "$VARIANT_DIR"/*.so
 
+          # Extract Torch version from variant dir name (e.g. torch210 -> 2.10.0)
+          VARIANT_NAME=$(basename "$VARIANT_DIR")
+          TORCH_DIGITS=$(echo "$VARIANT_NAME" | grep -oP '(?<=torch)\d+')
+          TORCH_MAJOR=${TORCH_DIGITS:0:1}
+          TORCH_MINOR=${TORCH_DIGITS:1}
+          TORCH_VERSION="${TORCH_MAJOR}.${TORCH_MINOR}.0"
+          echo "Detected Torch version: $TORCH_VERSION"
+          echo "torch_version=$TORCH_VERSION" >> "$GITHUB_OUTPUT"
+
       - name: Upload built kernel
         uses: actions/upload-artifact@v6
         with:
@@ -125,7 +137,7 @@ jobs:
 
   download-and-test:
     name: Download and test kernel via get_kernel
-    needs: upload
+    needs: [upload, init-and-build]
     runs-on:
       group: aws-g6-12xlarge-plus
     env:
@@ -143,7 +155,7 @@ jobs:
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install torch==2.10.0
+          uv pip install "torch==${{ needs.init-and-build.outputs.torch_version }}"
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From da37bc9f0d08366fbb4045b3ce8c736f7558afca Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 17:42:44 +0530
Subject: [PATCH 03/23] fix cargo failure.

---
 .github/workflows/test_e2e.yaml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 7795289a..d7d633e5 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -40,12 +40,12 @@ jobs:
           USER: runner
 
       - name: Build kernel-builder CLI
-        run: cargo build --release --manifest-path kernel-builder/Cargo.toml
+        run: nix build .#kernel-builder -L
 
       - name: Init kernel project
         run: |
           cd /tmp
-          $GITHUB_WORKSPACE/target/release/kernel-builder init \
+          $GITHUB_WORKSPACE/result/bin/kernel-builder init \
             --name kernels-test/e2e-test-kernel \
             --backends cuda
 
@@ -105,7 +105,7 @@ jobs:
         uses: actions/upload-artifact@v6
         with:
           name: kernel-builder-bin
-          path: ${{ github.workspace }}/target/release/kernel-builder
+          path: ${{ github.workspace }}/result/bin/kernel-builder
 
   upload:
     name: Upload kernel to Hub

From fe582588b24377984671792c2067a9c575df251d Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 18:44:57 +0530
Subject: [PATCH 04/23] empty


From db6abc902a9bb25a3d7380f36e7a3657bb337073 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 20:19:15 +0530
Subject: [PATCH 05/23] fix cachix.

---
 .github/workflows/test_e2e.yaml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index d7d633e5..26c65071 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -111,10 +111,11 @@ jobs:
     name: Upload kernel to Hub
     needs: init-and-build
     runs-on:
-      group: aws-g6-12xlarge-plus
+      group: aws-highmemory-32-plus-nix
     env:
       HF_TOKEN: ${{ secrets.HF_TOKEN }}
     steps:
+      - uses: DeterminateSystems/nix-installer-action@main
       - name: Download built kernel
         uses: actions/download-artifact@v7
         with:

From 7abe3d8ed54863b996cde4bc9a338fdff3a76ba4 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 20:32:53 +0530
Subject: [PATCH 06/23] up

---
 .github/workflows/test_e2e.yaml | 28 ++++++++++++----------------
 1 file changed, 12 insertions(+), 16 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 26c65071..66683326 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -101,12 +101,6 @@ jobs:
           name: e2e-built-kernel
           path: /tmp/e2e-test-kernel/
 
-      - name: Upload kernel-builder binary
-        uses: actions/upload-artifact@v6
-        with:
-          name: kernel-builder-bin
-          path: ${{ github.workspace }}/result/bin/kernel-builder
-
   upload:
     name: Upload kernel to Hub
     needs: init-and-build
@@ -115,25 +109,27 @@ jobs:
     env:
       HF_TOKEN: ${{ secrets.HF_TOKEN }}
     steps:
+      - uses: actions/checkout@v6
       - uses: DeterminateSystems/nix-installer-action@main
+      - uses: cachix/cachix-action@v16
+        with:
+          name: huggingface
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+        env:
+          USER: runner
+
+      - name: Build kernel-builder CLI
+        run: nix build .#kernel-builder -L
+
       - name: Download built kernel
         uses: actions/download-artifact@v7
         with:
           name: e2e-built-kernel
           path: /tmp/e2e-test-kernel
 
-      - name: Download kernel-builder binary
-        uses: actions/download-artifact@v7
-        with:
-          name: kernel-builder-bin
-          path: /tmp/bin
-
-      - name: Make binary executable
-        run: chmod +x /tmp/bin/kernel-builder
-
       - name: Upload kernel to Hub
         run: |
-          /tmp/bin/kernel-builder upload /tmp/e2e-test-kernel \
+          ./result/bin/kernel-builder upload /tmp/e2e-test-kernel \
             --repo-id kernels-test/kernels-upload-test
 
   download-and-test:

From 1031a965158d2159cfff4dcdcf8a3ed0c66d1222 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Mon, 30 Mar 2026 20:48:45 +0530
Subject: [PATCH 07/23] up

---
 .github/workflows/test_e2e.yaml | 44 ++++++---------------------------
 1 file changed, 7 insertions(+), 37 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 66683326..aa3c9736 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -18,12 +18,14 @@ concurrency:
   cancel-in-progress: true
 
 jobs:
-  init-and-build:
-    name: Init and build kernel
+  init-build-upload:
+    name: Init, build, and upload kernel
     outputs:
       torch_version: ${{ steps.detect-variant.outputs.torch_version }}
     runs-on:
       group: aws-highmemory-32-plus-nix
+    env:
+      HF_TOKEN: ${{ secrets.HF_TOKEN }}
     steps:
       - uses: actions/checkout@v6
       - uses: DeterminateSystems/nix-installer-action@main
@@ -95,46 +97,14 @@ jobs:
           echo "Detected Torch version: $TORCH_VERSION"
           echo "torch_version=$TORCH_VERSION" >> "$GITHUB_OUTPUT"
 
-      - name: Upload built kernel
-        uses: actions/upload-artifact@v6
-        with:
-          name: e2e-built-kernel
-          path: /tmp/e2e-test-kernel/
-
-  upload:
-    name: Upload kernel to Hub
-    needs: init-and-build
-    runs-on:
-      group: aws-highmemory-32-plus-nix
-    env:
-      HF_TOKEN: ${{ secrets.HF_TOKEN }}
-    steps:
-      - uses: actions/checkout@v6
-      - uses: DeterminateSystems/nix-installer-action@main
-      - uses: cachix/cachix-action@v16
-        with:
-          name: huggingface
-          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-        env:
-          USER: runner
-
-      - name: Build kernel-builder CLI
-        run: nix build .#kernel-builder -L
-
-      - name: Download built kernel
-        uses: actions/download-artifact@v7
-        with:
-          name: e2e-built-kernel
-          path: /tmp/e2e-test-kernel
-
       - name: Upload kernel to Hub
         run: |
-          ./result/bin/kernel-builder upload /tmp/e2e-test-kernel \
+          $GITHUB_WORKSPACE/result/bin/kernel-builder upload /tmp/e2e-test-kernel \
             --repo-id kernels-test/kernels-upload-test
 
   download-and-test:
     name: Download and test kernel via get_kernel
-    needs: [upload, init-and-build]
+    needs: init-build-upload
     runs-on:
       group: aws-g6-12xlarge-plus
     env:
@@ -152,7 +122,7 @@ jobs:
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install "torch==${{ needs.init-and-build.outputs.torch_version }}"
+          uv pip install "torch==${{ needs.init-build-upload.outputs.torch_version }}"
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From 4af65e016e3943fa5ee8a201821ce402021100ca Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 09:16:47 +0530
Subject: [PATCH 08/23] remove plan

---
 e2e-test-plan.md | 435 -----------------------------------------------
 1 file changed, 435 deletions(-)
 delete mode 100644 e2e-test-plan.md

diff --git a/e2e-test-plan.md b/e2e-test-plan.md
deleted file mode 100644
index dfc83fda..00000000
--- a/e2e-test-plan.md
+++ /dev/null
@@ -1,435 +0,0 @@
-# E2E Test Plan: kernel-builder init + build + upload + get_kernel
-
-## Goal
-
-Validate the full lifecycle: `kernel-builder init` creates a valid project, the template builds successfully, the built kernel can be uploaded to the Hub, and `get_kernel()` can download and use it.
-
----
-
-## Overview
-
-A single GitHub Actions workflow with three jobs for fault isolation:
-
-1. **init-and-build** (Nix runner) -- `kernel-builder init`, validate scaffold, `nix build` one CUDA variant.
-2. **upload** (GPU runner) -- `kernel-builder upload` the built artifacts to Hub.
-3. **download-and-test** (GPU runner) -- `get_kernel()` download + correctness check, cleanup.
-
-If init+build fails, we know the template or build infra is broken. If upload fails, the Rust upload logic is broken. If download+test fails, the Python `get_kernel()` path is broken. Each job's failure points to a specific component.
-
----
-
-## Speed considerations
-
-- **Build exactly one variant.** Use the `ci` Nix target which selects one variant per framework (one CUDA variant in our case).
-- **No matrix.** Single Python version (3.12), single Torch version (latest: 2.10), single backend (CUDA).
-- **Cachix.** Leverage the existing `huggingface` Cachix cache so Nix derivations are fetched, not rebuilt.
-- **Compile `kernel-builder` with `--release` once** in the build job and pass the binary via artifact to the GPU jobs (avoids compiling Rust twice).
-
----
-
-## Trigger paths
-
-The workflow should run on changes to the core components that affect this lifecycle:
-
-```yaml
-on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
-    paths:
-      - "kernel-builder/**"      # CLI: init, build, upload commands
-      - "kernels/src/**"         # Python library: get_kernel, variants, install
-      - "nix-builder/**"         # Nix build infrastructure
-      - "kernels-data/**"        # Shared config/data structures
-  workflow_dispatch:
-```
-
-This keeps the e2e tests focused on changes that could actually break the init/build/upload/download cycle, avoiding unnecessary runs on docs-only or CI config changes.
-
----
-
-## Job 1: `init-and-build`
-
-### What it validates
-
-- `kernel-builder init` produces a complete, well-formed project.
-- The generated `build.toml` is valid.
-- The project builds via Nix without errors.
-- The build produces a working kernel variant.
-
-### Implementation
-
-**Runner:** `aws-highmemory-32-plus-nix` (matches existing `build_kernel.yaml`)
-
-#### Step 1: Build `kernel-builder` CLI
-
-```bash
-cargo build --release --manifest-path kernel-builder/Cargo.toml
-```
-
-#### Step 2: Init a fresh kernel project
-
-```bash
-cd /tmp
-kernel-builder init --name kernels-test/e2e-test-kernel --backends cuda
-```
-
-Creates `/tmp/e2e-test-kernel/` with the full scaffold.
-
-#### Step 3: Validate the scaffold
-
-Quick checks that key files exist:
-
-```bash
-cd /tmp/e2e-test-kernel
-test -f build.toml
-test -f flake.nix
-test -f torch-ext/e2e_test_kernel/__init__.py
-test -f torch-ext/torch_binding.cpp
-test -f torch-ext/torch_binding.h
-test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
-test -f tests/test_e2e_test_kernel.py
-test -f example.py
-```
-
-Verify key fields in `build.toml`:
-- `name = "e2e-test-kernel"`
-- `repo-id = "kernels-test/e2e-test-kernel"`
-- `backend = "cuda"` appears in a kernel section
-
-#### Step 4: Patch flake.nix for local nix-builder
-
-The init template generates a `flake.nix` that references `github:huggingface/kernels` (the remote repo). For CI, we need it to use the **local checkout** so the test validates the current code:
-
-```bash
-cd /tmp/e2e-test-kernel
-sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
-```
-
-This changes `kernel-builder.url = "github:huggingface/kernels"` to `kernel-builder.url = "path:/path/to/checkout"`, matching how the example kernels work (`path:../../..`).
-
-#### Step 5: Build one CUDA variant with Nix
-
-```bash
-cd /tmp/e2e-test-kernel
-nix build .#ci -L
-cp -rL result/* build/
-```
-
-The `ci` Nix target builds exactly one variant per framework. This is the fastest path -- it's the same target the existing `build_kernel.yaml` CI uses.
-
-#### Step 6: Verify build artifacts
-
-```bash
-VARIANT_DIR=$(ls -d build/torch* | head -1)
-test -f "$VARIANT_DIR/__init__.py"
-test -f "$VARIANT_DIR/metadata.json"
-ls "$VARIANT_DIR"/*.so  # At least one shared object
-```
-
-#### Step 7: Upload artifacts
-
-Upload the built kernel directory and `kernel-builder` binary for downstream jobs.
-
----
-
-## Job 2: `upload`
-
-### What it validates
-
-- `kernel-builder upload` successfully pushes build artifacts to a Hub repo.
-
-### Implementation
-
-**Runner:** `aws-g6-12xlarge-plus` (GPU runner -- needed for Job 3 anyway, reuse the same runner group)
-**Depends on:** `init-and-build`
-
-#### Step 1: Download artifacts from Job 1
-
-Download the built kernel directory and `kernel-builder` binary.
-
-#### Step 2: Upload kernel to Hub
-
-```bash
-kernel-builder upload /tmp/e2e-test-kernel \
-  --repo-id kernels-test/kernels-upload-test \
-  --private
-```
-
-Uses `HF_TOKEN` secret for authentication.
-
----
-
-## Job 3: `download-and-test`
-
-### What it validates
-
-- `get_kernel()` can download the uploaded kernel and resolve the correct variant.
-- The imported module is callable and produces correct results.
-
-### Implementation
-
-**Runner:** `aws-g6-12xlarge-plus` (GPU runner)
-**Depends on:** `upload`
-
-#### Step 1: Install Python deps
-
-```bash
-cd kernels
-uv sync --all-extras --dev
-uv pip install torch==2.10.0
-```
-
-#### Step 2: Download and test via `get_kernel()`
-
-```python
-import torch
-from kernels import get_kernel
-
-kernel = get_kernel("kernels-test/kernels-upload-test", version=1)
-
-x = torch.randn(1024, 1024, dtype=torch.float32, device="cuda")
-result = kernel.e2e_test_kernel(x)
-expected = x + 1.0
-torch.testing.assert_close(result, expected)
-print("E2E test passed!")
-```
-
-#### Step 3: Cleanup (always runs)
-
-Delete the Hub repo regardless of test outcome:
-
-```python
-from huggingface_hub import HfApi
-api = HfApi()
-api.delete_repo("kernels-test/kernels-upload-test")
-```
-
----
-
-## Key risks and mitigations
-
-| Risk | Mitigation |
-|------|------------|
-| Init template `flake.nix` points to remote nix-builder | `sed` patch to use `path:$GITHUB_WORKSPACE` |
-| Leftover repos on failure | `if: always()` cleanup step in Job 3 |
-| Nix build is slow | Use `ci` target (one variant) + Cachix caching |
-| Rust recompilation on GPU runner | Pass pre-built binary via artifact |
-
----
-
-## Complete workflow file
-
-```yaml
-name: "E2E: kernel-builder init + build + upload + download"
-
-on:
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
-    paths:
-      - "kernel-builder/**"
-      - "kernels/src/**"
-      - "nix-builder/**"
-      - "kernels-data/**"
-  workflow_dispatch:
-
-concurrency:
-  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
-  cancel-in-progress: true
-
-jobs:
-  init-and-build:
-    name: Init and build kernel
-    runs-on:
-      group: aws-highmemory-32-plus-nix
-    steps:
-      - uses: actions/checkout@v6
-      - uses: DeterminateSystems/nix-installer-action@main
-        with:
-          extra-conf: |
-            max-jobs = 8
-            cores = 12
-            sandbox-fallback = false
-      - uses: cachix/cachix-action@v16
-        with:
-          name: huggingface
-          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
-        env:
-          USER: runner
-
-      - name: Build kernel-builder CLI
-        run: cargo build --release --manifest-path kernel-builder/Cargo.toml
-
-      - name: Init kernel project
-        run: |
-          cd /tmp
-          $GITHUB_WORKSPACE/target/release/kernel-builder init \
-            --name kernels-test/e2e-test-kernel \
-            --backends cuda
-
-      - name: Validate scaffold
-        run: |
-          cd /tmp/e2e-test-kernel
-          test -f build.toml
-          test -f flake.nix
-          test -f torch-ext/e2e_test_kernel/__init__.py
-          test -f torch-ext/torch_binding.cpp
-          test -f torch-ext/torch_binding.h
-          test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
-          test -f tests/test_e2e_test_kernel.py
-          test -f example.py
-          grep -q 'name = "e2e-test-kernel"' build.toml
-          grep -q 'repo-id = "kernels-test/e2e-test-kernel"' build.toml
-          grep -q 'backend = "cuda"' build.toml
-
-      - name: Patch flake.nix to use local nix-builder
-        run: |
-          cd /tmp/e2e-test-kernel
-          sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
-
-      - name: Build one CUDA variant
-        run: |
-          cd /tmp/e2e-test-kernel
-          nix build .#ci -L
-          mkdir -p build
-          cp -rL result/* build/
-
-      - name: Verify build artifacts
-        run: |
-          cd /tmp/e2e-test-kernel
-          VARIANT_DIR=$(ls -d build/torch* | head -1)
-          echo "Built variant: $VARIANT_DIR"
-          test -f "$VARIANT_DIR/__init__.py"
-          test -f "$VARIANT_DIR/metadata.json"
-          ls "$VARIANT_DIR"/*.so
-
-      - name: Upload built kernel
-        uses: actions/upload-artifact@v6
-        with:
-          name: e2e-built-kernel
-          path: /tmp/e2e-test-kernel/
-
-      - name: Upload kernel-builder binary
-        uses: actions/upload-artifact@v6
-        with:
-          name: kernel-builder-bin
-          path: ${{ github.workspace }}/target/release/kernel-builder
-
-  upload:
-    name: Upload kernel to Hub
-    needs: init-and-build
-    runs-on:
-      group: aws-g6-12xlarge-plus
-    env:
-      HF_TOKEN: ${{ secrets.HF_TOKEN }}
-    steps:
-      - name: Download built kernel
-        uses: actions/download-artifact@v7
-        with:
-          name: e2e-built-kernel
-          path: /tmp/e2e-test-kernel
-
-      - name: Download kernel-builder binary
-        uses: actions/download-artifact@v7
-        with:
-          name: kernel-builder-bin
-          path: /tmp/bin
-
-      - name: Make binary executable
-        run: chmod +x /tmp/bin/kernel-builder
-
-      - name: Upload kernel to Hub
-        run: |
-          /tmp/bin/kernel-builder upload /tmp/e2e-test-kernel \
-            --repo-id kernels-test/kernels-upload-test \
-
-  download-and-test:
-    name: Download and test kernel via get_kernel
-    needs: upload
-    runs-on:
-      group: aws-g6-12xlarge-plus
-    env:
-      HF_TOKEN: ${{ secrets.HF_TOKEN }}
-      UV_PYTHON_PREFERENCE: only-managed
-    steps:
-      - uses: actions/checkout@v6
-
-      - name: Install uv and set Python version
-        uses: astral-sh/setup-uv@v7
-        with:
-          python-version: "3.12"
-
-      - name: Install Python deps
-        working-directory: ./kernels
-        run: |
-          uv sync --all-extras --dev
-          uv pip install torch==2.10.0
-
-      - name: Test get_kernel download and usage
-        working-directory: ./kernels
-        run: |
-          uv run python -c "
-          import torch
-          from kernels import get_kernel
-
-          kernel = get_kernel('kernels-test/kernels-upload-test', version=1)
-
-          x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
-          result = kernel.e2e_test_kernel(x)
-          expected = x + 1.0
-          torch.testing.assert_close(result, expected)
-          print('E2E test passed: get_kernel + correctness check')
-          "
-
-      - name: Cleanup Hub repo
-        if: always()
-        working-directory: ./kernels
-        run: |
-          uv run python -c "
-          from huggingface_hub import HfApi
-          api = HfApi()
-          try:
-              api.delete_repo('kernels-test/kernels-upload-test')
-              print('Cleaned up repo')
-          except Exception as e:
-              print(f'Cleanup warning: {e}')
-          "
-```
-
----
-
-## Files to create
-
-| File | Purpose |
-|------|---------|
-| `.github/workflows/test_e2e.yaml` | The workflow above |
-
-No new Python test files needed -- the e2e test is self-contained in the workflow.
-
----
-
-## Execution flow
-
-```
-Job 1: init-and-build (Nix runner, no GPU)
-  1. cargo build kernel-builder
-  2. kernel-builder init --backends cuda
-  3. validate scaffold files + build.toml
-  4. patch flake.nix → local nix-builder
-  5. nix build .#ci (one CUDA variant)
-  6. verify artifacts (*.so, metadata.json)
-  → artifacts: built kernel dir + kernel-builder binary
-
-Job 2: upload (GPU runner)
-  7. kernel-builder upload → Hub
-  ✗ Failure here = upload logic is broken
-
-Job 3: download-and-test (GPU runner)
-  8. get_kernel() → download + import
-  9. call kernel function + assert correctness
-  10. delete Hub repo (always)
-  ✗ Failure here = Python get_kernel / variant resolution is broken
-```

From d1152ffecd6b092a010159a9cc51c855f5dbe05a Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 09:24:13 +0530
Subject: [PATCH 09/23] up

---
 .github/workflows/test_e2e.yaml | 18 ++++++------------
 1 file changed, 6 insertions(+), 12 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index aa3c9736..d4f2073e 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -13,6 +13,9 @@ on:
       - ".github/workflows/test_e2e.yaml"
   workflow_dispatch:
 
+env:
+  E2E_REPO_ID: kernels-test/kernels-upload-test
+
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
   cancel-in-progress: true
@@ -100,7 +103,7 @@ jobs:
       - name: Upload kernel to Hub
         run: |
           $GITHUB_WORKSPACE/result/bin/kernel-builder upload /tmp/e2e-test-kernel \
-            --repo-id kernels-test/kernels-upload-test
+            --repo-id ${{ env.E2E_REPO_ID }}
 
   download-and-test:
     name: Download and test kernel via get_kernel
@@ -131,7 +134,7 @@ jobs:
           import torch
           from kernels import get_kernel
 
-          kernel = get_kernel('kernels-test/kernels-upload-test', version=1)
+          kernel = get_kernel('${{ env.E2E_REPO_ID }}', version=1)
 
           x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
           result = kernel.e2e_test_kernel(x)
@@ -143,13 +146,4 @@ jobs:
       - name: Cleanup Hub repo
         if: always()
         working-directory: ./kernels
-        run: |
-          uv run python -c "
-          from huggingface_hub import HfApi
-          api = HfApi()
-          try:
-              api.delete_repo('kernels-test/kernels-upload-test')
-              print('Cleaned up repo')
-          except Exception as e:
-              print(f'Cleanup warning: {e}')
-          "
+        run: uv run huggingface-cli delete-repo ${{ env.E2E_REPO_ID }} --yes || true

From 035577a9440c5431cc956264ae08070ba0b19ec8 Mon Sep 17 00:00:00 2001
From: Sayak Paul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 14:27:50 +0530
Subject: [PATCH 10/23] Apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Daniël de Kok <me@danieldk.eu>
---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index d4f2073e..5a7f882a 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -50,7 +50,7 @@ jobs:
       - name: Init kernel project
         run: |
           cd /tmp
-          $GITHUB_WORKSPACE/result/bin/kernel-builder init \
+          nix run $GITHUB_WORKSPACE#kernel-builder -- init \
             --name kernels-test/e2e-test-kernel \
             --backends cuda
 

From 380bf24eac03281f50ba73394a10e904fcc1fed3 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 14:42:31 +0530
Subject: [PATCH 11/23] use kernel-builder buil

---
 .github/workflows/test_e2e.yaml | 27 +++++----------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 5a7f882a..6dd84963 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -23,8 +23,6 @@ concurrency:
 jobs:
   init-build-upload:
     name: Init, build, and upload kernel
-    outputs:
-      torch_version: ${{ steps.detect-variant.outputs.torch_version }}
     runs-on:
       group: aws-highmemory-32-plus-nix
     env:
@@ -44,9 +42,6 @@ jobs:
         env:
           USER: runner
 
-      - name: Build kernel-builder CLI
-        run: nix build .#kernel-builder -L
-
       - name: Init kernel project
         run: |
           cd /tmp
@@ -74,15 +69,12 @@ jobs:
           cd /tmp/e2e-test-kernel
           sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
 
-      - name: Build one CUDA variant
+      - name: Build kernel
         run: |
           cd /tmp/e2e-test-kernel
-          nix build .#ci -L
-          mkdir -p build
-          cp -rL result/* build/
+          nix run $GITHUB_WORKSPACE#kernel-builder -- build . -L
 
-      - name: Verify build artifacts and detect Torch version
-        id: detect-variant
+      - name: Verify build artifacts
         run: |
           cd /tmp/e2e-test-kernel
           VARIANT_DIR=$(ls -d build/torch* | head -1)
@@ -91,18 +83,9 @@ jobs:
           test -f "$VARIANT_DIR/metadata.json"
           ls "$VARIANT_DIR"/*.so
 
-          # Extract Torch version from variant dir name (e.g. torch210 -> 2.10.0)
-          VARIANT_NAME=$(basename "$VARIANT_DIR")
-          TORCH_DIGITS=$(echo "$VARIANT_NAME" | grep -oP '(?<=torch)\d+')
-          TORCH_MAJOR=${TORCH_DIGITS:0:1}
-          TORCH_MINOR=${TORCH_DIGITS:1}
-          TORCH_VERSION="${TORCH_MAJOR}.${TORCH_MINOR}.0"
-          echo "Detected Torch version: $TORCH_VERSION"
-          echo "torch_version=$TORCH_VERSION" >> "$GITHUB_OUTPUT"
-
       - name: Upload kernel to Hub
         run: |
-          $GITHUB_WORKSPACE/result/bin/kernel-builder upload /tmp/e2e-test-kernel \
+          nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/e2e-test-kernel \
             --repo-id ${{ env.E2E_REPO_ID }}
 
   download-and-test:
@@ -125,7 +108,7 @@ jobs:
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install "torch==${{ needs.init-build-upload.outputs.torch_version }}"
+          uv pip install torch
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From 8a721f8a0da3645b18e3a9d4595a1c4643d41e93 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 14:59:20 +0530
Subject: [PATCH 12/23] add

---
 .github/workflows/test_e2e.yaml | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 6dd84963..113a5e40 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -15,6 +15,7 @@ on:
 
 env:
   E2E_REPO_ID: kernels-test/kernels-upload-test
+  E2E_BRANCH: e2e-${{ github.event.pull_request.number || github.run_id }}-${{ github.run_attempt }}
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
@@ -86,7 +87,8 @@ jobs:
       - name: Upload kernel to Hub
         run: |
           nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/e2e-test-kernel \
-            --repo-id ${{ env.E2E_REPO_ID }}
+            --repo-id ${{ env.E2E_REPO_ID }} \
+            --branch ${{ env.E2E_BRANCH }}
 
   download-and-test:
     name: Download and test kernel via get_kernel
@@ -117,7 +119,7 @@ jobs:
           import torch
           from kernels import get_kernel
 
-          kernel = get_kernel('${{ env.E2E_REPO_ID }}', version=1)
+          kernel = get_kernel('${{ env.E2E_REPO_ID }}', revision='${{ env.E2E_BRANCH }}')
 
           x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
           result = kernel.e2e_test_kernel(x)
@@ -125,8 +127,3 @@ jobs:
           torch.testing.assert_close(result, expected)
           print('E2E test passed: get_kernel + correctness check')
           "
-
-      - name: Cleanup Hub repo
-        if: always()
-        working-directory: ./kernels
-        run: uv run huggingface-cli delete-repo ${{ env.E2E_REPO_ID }} --yes || true

From 87f57fcb11be82ccd79d365d6e9842904c192dfa Mon Sep 17 00:00:00 2001
From: Sayak Paul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 15:04:42 +0530
Subject: [PATCH 13/23] Apply suggestions from code review
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Daniël de Kok <me@danieldk.eu>
---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 113a5e40..75f54e2d 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -47,7 +47,7 @@ jobs:
         run: |
           cd /tmp
           nix run $GITHUB_WORKSPACE#kernel-builder -- init \
-            --name kernels-test/e2e-test-kernel \
+            --name ${{ env.E2E_REPO_ID }} \
             --backends cuda
 
       - name: Validate scaffold

From 13d526830689d6cc9e69305ee0a863609de8639c Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 15:17:05 +0530
Subject: [PATCH 14/23] fix more

---
 .github/workflows/test_e2e.yaml | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 75f54e2d..ca63cb9c 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -52,32 +52,32 @@ jobs:
 
       - name: Validate scaffold
         run: |
-          cd /tmp/e2e-test-kernel
+          cd /tmp/kernels-upload-test
           test -f build.toml
           test -f flake.nix
-          test -f torch-ext/e2e_test_kernel/__init__.py
+          test -f torch-ext/kernels_upload_test/__init__.py
           test -f torch-ext/torch_binding.cpp
           test -f torch-ext/torch_binding.h
-          test -f e2e_test_kernel_cuda/e2e_test_kernel.cu
-          test -f tests/test_e2e_test_kernel.py
+          test -f kernels_upload_test_cuda/kernels_upload_test.cu
+          test -f tests/test_kernels_upload_test.py
           test -f example.py
-          grep -q 'name = "e2e-test-kernel"' build.toml
-          grep -q 'repo-id = "kernels-test/e2e-test-kernel"' build.toml
+          grep -q 'name = "kernels-upload-test"' build.toml
+          grep -q 'repo-id = "kernels-test/kernels-upload-test"' build.toml
           grep -q 'backend = "cuda"' build.toml
 
       - name: Patch flake.nix to use local nix-builder
         run: |
-          cd /tmp/e2e-test-kernel
+          cd /tmp/kernels-upload-test
           sed -i 's|github:huggingface/kernels|path:'"$GITHUB_WORKSPACE"'|' flake.nix
 
       - name: Build kernel
         run: |
-          cd /tmp/e2e-test-kernel
+          cd /tmp/kernels-upload-test
           nix run $GITHUB_WORKSPACE#kernel-builder -- build . -L
 
       - name: Verify build artifacts
         run: |
-          cd /tmp/e2e-test-kernel
+          cd /tmp/kernels-upload-test
           VARIANT_DIR=$(ls -d build/torch* | head -1)
           echo "Built variant: $VARIANT_DIR"
           test -f "$VARIANT_DIR/__init__.py"
@@ -86,7 +86,7 @@ jobs:
 
       - name: Upload kernel to Hub
         run: |
-          nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/e2e-test-kernel \
+          nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/kernels-upload-test \
             --repo-id ${{ env.E2E_REPO_ID }} \
             --branch ${{ env.E2E_BRANCH }}
 
@@ -122,7 +122,7 @@ jobs:
           kernel = get_kernel('${{ env.E2E_REPO_ID }}', revision='${{ env.E2E_BRANCH }}')
 
           x = torch.randn(1024, 1024, dtype=torch.float32, device='cuda')
-          result = kernel.e2e_test_kernel(x)
+          result = kernel.kernels_upload_test(x)
           expected = x + 1.0
           torch.testing.assert_close(result, expected)
           print('E2E test passed: get_kernel + correctness check')

From 0234a8ce940dec9bc6ba2fa8e1ebc7ba08daaffa Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 15:25:50 +0530
Subject: [PATCH 15/23] more

---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index ca63cb9c..75279926 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -73,7 +73,7 @@ jobs:
       - name: Build kernel
         run: |
           cd /tmp/kernels-upload-test
-          nix run $GITHUB_WORKSPACE#kernel-builder -- build . -L
+          nix run $GITHUB_WORKSPACE#kernel-builder -- build-and-copy . -L
 
       - name: Verify build artifacts
         run: |

From 7b5eb82a170dc501a9810e18761ce30fb69065d3 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 15:39:13 +0530
Subject: [PATCH 16/23] remove repo-id from the upload command.

---
 .github/workflows/test_e2e.yaml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 75279926..ae3a30d6 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -86,9 +86,7 @@ jobs:
 
       - name: Upload kernel to Hub
         run: |
-          nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/kernels-upload-test \
-            --repo-id ${{ env.E2E_REPO_ID }} \
-            --branch ${{ env.E2E_BRANCH }}
+          nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/kernels-upload-test --branch ${{ env.E2E_BRANCH }}
 
   download-and-test:
     name: Download and test kernel via get_kernel

From 82e9067da68f54c4d256b399545ff13c6d3a557f Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 19:00:45 +0530
Subject: [PATCH 17/23] scope the token.

---
 .github/workflows/test_e2e.yaml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index ae3a30d6..6557e6f8 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -26,8 +26,6 @@ jobs:
     name: Init, build, and upload kernel
     runs-on:
       group: aws-highmemory-32-plus-nix
-    env:
-      HF_TOKEN: ${{ secrets.HF_TOKEN }}
     steps:
       - uses: actions/checkout@v6
       - uses: DeterminateSystems/nix-installer-action@main
@@ -85,6 +83,8 @@ jobs:
           ls "$VARIANT_DIR"/*.so
 
       - name: Upload kernel to Hub
+        env:
+          HF_TOKEN: ${{ secrets.HF_TOKEN }}
         run: |
           nix run $GITHUB_WORKSPACE#kernel-builder -- upload /tmp/kernels-upload-test --branch ${{ env.E2E_BRANCH }}
 
@@ -94,7 +94,6 @@ jobs:
     runs-on:
       group: aws-g6-12xlarge-plus
     env:
-      HF_TOKEN: ${{ secrets.HF_TOKEN }}
       UV_PYTHON_PREFERENCE: only-managed
     steps:
       - uses: actions/checkout@v6
@@ -112,6 +111,8 @@ jobs:
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels
+        env:
+          HF_TOKEN: ${{ secrets.HF_TOKEN }}
         run: |
           uv run python -c "
           import torch

From 56beb52353d49a24cb1e82cbd9d95f21d5c5a8f7 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 19:34:33 +0530
Subject: [PATCH 18/23] upgrade forcefully.

---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 6557e6f8..6d8c1df2 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -107,7 +107,7 @@ jobs:
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install torch
+          uv pip install --upgrade torch
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From a0f806ec965b03eee5cb68ffc3764aaa590e7d88 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 20:53:04 +0530
Subject: [PATCH 19/23] check

---
 .github/workflows/test_e2e.yaml | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 6d8c1df2..8b1c2e99 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -103,11 +103,21 @@ jobs:
         with:
           python-version: "3.12"
 
+      - name: Detect CUDA version
+        id: cuda
+        run: |
+          nvidia-smi
+          CUDA_RT=$(nvidia-smi | grep -oP 'CUDA Version: \K[\d.]+')
+          CUDA_TAG="cu$(echo $CUDA_RT | tr -d '.')"
+          echo "Detected CUDA: $CUDA_RT -> $CUDA_TAG"
+          echo "cuda_tag=$CUDA_TAG" >> "$GITHUB_OUTPUT"
+
       - name: Install Python deps
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install --upgrade torch
+          uv pip install --upgrade torch --index-url https://download.pytorch.org/whl/${{ steps.cuda.outputs.cuda_tag }}
+          pip show torch
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From 66795d1c8c635389ceffe24bdbca03939bf2eeb3 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 21:03:42 +0530
Subject: [PATCH 20/23] switch to test_kernels runner

---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 8b1c2e99..20d11c14 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -92,7 +92,7 @@ jobs:
     name: Download and test kernel via get_kernel
     needs: init-build-upload
     runs-on:
-      group: aws-g6-12xlarge-plus
+      group: aws-g6-24xlarge
     env:
       UV_PYTHON_PREFERENCE: only-managed
     steps:

From 46436ae70382276e91b30247163686ad3b9c0941 Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 21:17:06 +0530
Subject: [PATCH 21/23] up

---
 .github/workflows/test_e2e.yaml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 20d11c14..19ab1262 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -117,7 +117,7 @@ jobs:
         run: |
           uv sync --all-extras --dev
           uv pip install --upgrade torch --index-url https://download.pytorch.org/whl/${{ steps.cuda.outputs.cuda_tag }}
-          pip show torch
+          uv pip show torch
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From a82db5b5353367a60f20480027923dfe9bd222be Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 21:36:48 +0530
Subject: [PATCH 22/23] abi compilation issues.

---
 .github/workflows/test_e2e.yaml | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 19ab1262..10fc445f 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -103,21 +103,12 @@ jobs:
         with:
           python-version: "3.12"
 
-      - name: Detect CUDA version
-        id: cuda
-        run: |
-          nvidia-smi
-          CUDA_RT=$(nvidia-smi | grep -oP 'CUDA Version: \K[\d.]+')
-          CUDA_TAG="cu$(echo $CUDA_RT | tr -d '.')"
-          echo "Detected CUDA: $CUDA_RT -> $CUDA_TAG"
-          echo "cuda_tag=$CUDA_TAG" >> "$GITHUB_OUTPUT"
-
       - name: Install Python deps
         working-directory: ./kernels
         run: |
           uv sync --all-extras --dev
-          uv pip install --upgrade torch --index-url https://download.pytorch.org/whl/${{ steps.cuda.outputs.cuda_tag }}
-          uv pip show torch
+          uv pip install --upgrade torch
+          uv run python -c "import torch; print(f'torch={torch.__version__}, cuda={torch.version.cuda}, cxx11_abi={torch.compiled_with_cxx11_abi()}')"
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels

From b5eab6440bf88afb63400886141456ed5f64d0be Mon Sep 17 00:00:00 2001
From: sayakpaul <spsayakpaul@gmail.com>
Date: Tue, 31 Mar 2026 22:40:00 +0530
Subject: [PATCH 23/23] up

---
 .github/workflows/test_e2e.yaml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/test_e2e.yaml b/.github/workflows/test_e2e.yaml
index 10fc445f..44a2166e 100644
--- a/.github/workflows/test_e2e.yaml
+++ b/.github/workflows/test_e2e.yaml
@@ -108,14 +108,14 @@ jobs:
         run: |
           uv sync --all-extras --dev
           uv pip install --upgrade torch
-          uv run python -c "import torch; print(f'torch={torch.__version__}, cuda={torch.version.cuda}, cxx11_abi={torch.compiled_with_cxx11_abi()}')"
+          uv run --no-sync python -c "import torch; print(f'torch={torch.__version__}, cuda={torch.version.cuda}, cxx11_abi={torch.compiled_with_cxx11_abi()}')"
 
       - name: Test get_kernel download and usage
         working-directory: ./kernels
         env:
           HF_TOKEN: ${{ secrets.HF_TOKEN }}
         run: |
-          uv run python -c "
+          uv run --no-sync python -c "
           import torch
           from kernels import get_kernel