diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 000000000..33aee19ec
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1,8 @@
+# Ported kernels are generated: <kernel>/port/port.kdl plus <kernel>/port/overlay
+# are the inputs, and <kernel>/src is kernel-port's output, committed so that
+# what ships stays reviewable and auditable.
+#
+# Collapse the generated tree in diffs so review lands on the inputs. The output
+# is not taken on trust: .github/workflows/check-ports.yaml regenerates every
+# port and fails if <kernel>/src does not match byte for byte.
+*/src/** linguist-generated=true
diff --git a/.github/scripts/check_kernel_test_versions.py b/.github/scripts/check_kernel_test_versions.py
index 433e5a7f1..f271084cc 100644
--- a/.github/scripts/check_kernel_test_versions.py
+++ b/.github/scripts/check_kernel_test_versions.py
@@ -40,7 +40,9 @@ def discover_kernels(repository_root: Path) -> list[Kernel]:
         if not manifest.is_file():
             # Ported kernels keep generated sources and build.toml under src/.
             manifest = root / "src" / "build.toml"
-        if not manifest.is_file() or not (root / "tests").is_dir():
+        # A ported kernel generates its tests next to build.toml in src/.
+        tests_root = manifest.parent if (manifest.parent / "tests").is_dir() else root
+        if not manifest.is_file() or not (tests_root / "tests").is_dir():
             continue
 
         with manifest.open("rb") as handle:
@@ -52,7 +54,7 @@ def discover_kernels(repository_root: Path) -> list[Kernel]:
             raise ValueError(f"{manifest}: [general.hub].repo-id must be a string")
         if type(version) is not int:
             raise ValueError(f"{manifest}: [general].version must be an integer")
-        kernels.append(Kernel(root=root, repo_id=repo_id, version=version))
+        kernels.append(Kernel(root=tests_root, repo_id=repo_id, version=version))
     return kernels
 
 
diff --git a/.github/scripts/kernel_maintainers.py b/.github/scripts/kernel_maintainers.py
index 5bd220db1..ee5ca0383 100755
--- a/.github/scripts/kernel_maintainers.py
+++ b/.github/scripts/kernel_maintainers.py
@@ -22,7 +22,9 @@ def load_registry() -> dict:
 
 def check_registry() -> None:
     registry = load_registry()
+    # Ported kernels keep build.toml in <kernel>/src.
     kernels = {path.parent.name for path in Path(".").glob("*/build.toml")}
+    kernels |= {path.parent.parent.name for path in Path(".").glob("*/src/build.toml")}
     registered = set(registry)
 
     problems = [
diff --git a/.github/scripts/pr_kernel_build_guidance.py b/.github/scripts/pr_kernel_build_guidance.py
index 1f100203d..4be60b4dd 100644
--- a/.github/scripts/pr_kernel_build_guidance.py
+++ b/.github/scripts/pr_kernel_build_guidance.py
@@ -43,7 +43,10 @@ def paginate(url: str, token: str) -> list[dict]:
 
 
 def kernel_directories(root: Path) -> set[str]:
-    return {manifest.parent.name for manifest in root.glob("*/build.toml")}
+    # Ported kernels keep build.toml in <kernel>/src.
+    return {manifest.parent.name for manifest in root.glob("*/build.toml")} | {
+        manifest.parent.parent.name for manifest in root.glob("*/src/build.toml")
+    }
 
 
 def is_documentation(path: PurePosixPath) -> bool:
@@ -55,7 +58,8 @@ def touched_source_kernels(files: list[dict], existing_kernels: set[str]) -> lis
     new_kernels = {
         path.parts[0]
         for path in paths
-        if len(path.parts) == 2 and path.name == "build.toml"
+        if path.name == "build.toml"
+        and (len(path.parts) == 2 or (len(path.parts) == 3 and path.parts[1] == "src"))
     }
     kernels = existing_kernels | new_kernels
     touched = set(new_kernels)
diff --git a/.github/scripts/test_check_kernel_test_versions.py b/.github/scripts/test_check_kernel_test_versions.py
index d60b8caaf..27eea2b86 100644
--- a/.github/scripts/test_check_kernel_test_versions.py
+++ b/.github/scripts/test_check_kernel_test_versions.py
@@ -46,6 +46,21 @@ def test_matching_import_with_nested_manifest(tmp_path):
     assert checker.check_repository(tmp_path) == ([], 1, 1)
 
 
+def test_ported_kernel_tests_under_src(tmp_path):
+    kernel = tmp_path / "example"
+    (kernel / "src" / "tests").mkdir(parents=True)
+    (kernel / "src" / "build.toml").write_text(
+        '[general]\nversion = 2\n\n[general.hub]\nrepo-id = "kernels-community/example"\n'
+    )
+    (kernel / "src" / "tests" / "test_example.py").write_text(
+        "from kernels import get_kernel\n"
+        'example = get_kernel("kernels-community/example", version=1)\n'
+    )
+
+    problems, _, _ = checker.check_repository(tmp_path)
+    assert len(problems) == 1
+
+
 def test_matching_call_is_formatting_agnostic(tmp_path):
     kernel = write_kernel(tmp_path)
     (kernel / "tests" / "test_example.py").write_text(
diff --git a/.github/scripts/test_pr_kernel_build_guidance.py b/.github/scripts/test_pr_kernel_build_guidance.py
index 8ad5fed83..b7218814c 100644
--- a/.github/scripts/test_pr_kernel_build_guidance.py
+++ b/.github/scripts/test_pr_kernel_build_guidance.py
@@ -39,6 +39,22 @@ def test_unknown_extensions_and_test_changes_are_build_relevant(tmp_path):
     ) == ["relu"]
 
 
+def test_detects_ported_kernel_source(tmp_path):
+    (tmp_path / "einops" / "src").mkdir(parents=True)
+    (tmp_path / "einops" / "src" / "build.toml").touch()
+    files = [{"filename": "einops/port/port.kdl", "status": "modified"}]
+
+    assert guidance.touched_source_kernels(
+        files, guidance.kernel_directories(tmp_path)
+    ) == ["einops"]
+
+
+def test_detects_new_ported_kernel_from_added_manifest():
+    files = [{"filename": "new-kernel/src/build.toml", "status": "added"}]
+
+    assert guidance.touched_source_kernels(files, set()) == ["new-kernel"]
+
+
 def test_detects_new_kernel_from_added_manifest():
     files = [
         {"filename": "new-kernel/build.toml", "status": "added"},
diff --git a/.github/workflows/build-release-dispatch.yaml b/.github/workflows/build-release-dispatch.yaml
index c67b72a4a..cc09b4faa 100644
--- a/.github/workflows/build-release-dispatch.yaml
+++ b/.github/workflows/build-release-dispatch.yaml
@@ -40,7 +40,11 @@ jobs:
           KERNEL: ${{ inputs.kernel_name }}
         run: |
           if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
-            if [ -d "$KERNEL" ] && [ -f "$KERNEL/flake.nix" ] && [ -f "$KERNEL/build.toml" ]; then
+            # Ported kernels keep build.toml in <kernel>/src; the flake stays at
+            # <kernel> and points nix at it.
+            CONFIG="$KERNEL"
+            [ -f "$KERNEL/src/build.toml" ] && CONFIG="$KERNEL/src"
+            if [ -d "$KERNEL" ] && [ -f "$KERNEL/flake.nix" ] && [ -f "$CONFIG/build.toml" ]; then
               echo "kernel=$KERNEL" >> $GITHUB_OUTPUT
               echo "skip=false" >> $GITHUB_OUTPUT
             else
diff --git a/.github/workflows/check-ports.yaml b/.github/workflows/check-ports.yaml
new file mode 100644
index 000000000..b4e57ced7
--- /dev/null
+++ b/.github/workflows/check-ports.yaml
@@ -0,0 +1,50 @@
+name: Check Ports
+
+# Verify committed src trees match their port recipes. PRs check changed ports;
+# checker changes, pushes to main, scheduled runs and manual runs check all ports.
+on:
+  push:
+    branches: [main]
+  # Catch kernel-port regressions even when no port changes.
+  schedule:
+    - cron: "0 6 * * *"
+  pull_request:
+    branches: [main]
+    types: [opened, synchronize, reopened]
+    paths:
+      - "*/port/**"
+      - "*/src/**"
+      - "scripts/check_ports.py"
+      - ".github/workflows/check-ports.yaml"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  check-ports:
+    name: Check ports reproduce
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+        with:
+          fetch-depth: 0
+
+      - uses: DeterminateSystems/nix-installer-action@ef8a148080ab6020fd15196c2084a2eea5ff2d25 # v22
+
+      - name: Regenerate selected ports and compare
+        env:
+          # Refresh the runner to catch upstream changes.
+          # TODO: switch back to main once huggingface/kernels#877 is merged.
+          KERNEL_PORT: "nix run --refresh github:huggingface/kernels/kernel-port-no-importlib#kernel-port --"
+          BASE_REF: ${{ github.event_name == 'pull_request' && format('origin/{0}', github.base_ref) || '' }}
+        run: |
+          if [ -n "$BASE_REF" ]; then
+            python3 scripts/check_ports.py --changed-since "$BASE_REF"
+          else
+            python3 scripts/check_ports.py
+          fi
diff --git a/.gitignore b/.gitignore
index 4dcaf8670..c9216b6cf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,6 +15,7 @@ build
 # Editor files
 .*
 !.github/
+!/.gitattributes
 
 # Python stuff
 __pycache__/
diff --git a/einops/flake.nix b/einops/flake.nix
index 0b2a92f1e..70f28b83d 100644
--- a/einops/flake.nix
+++ b/einops/flake.nix
@@ -1,5 +1,5 @@
 {
-  description = "Flake for eigen kernel";
+  description = "Flake for einops kernel";
 
   inputs = {
     kernel-builder.url = "github:huggingface/kernels";
@@ -12,6 +12,6 @@
     }:
     kernel-builder.lib.genKernelFlakeOutputs {
       inherit self;
-      path = ./.;
+      path = ./src;
     };
 }
diff --git a/einops/port/overlay/tests/conftest.py b/einops/port/overlay/tests/conftest.py
new file mode 100644
index 000000000..3fe86a864
--- /dev/null
+++ b/einops/port/overlay/tests/conftest.py
@@ -0,0 +1,4 @@
+import os
+
+# Use the CI backends by default, while allowing local overrides.
+os.environ.setdefault("EINOPS_TEST_BACKENDS", "torch,numpy")
diff --git a/einops/port/port.kdl b/einops/port/port.kdl
new file mode 100644
index 000000000..89ac6b50b
--- /dev/null
+++ b/einops/port/port.kdl
@@ -0,0 +1,78 @@
+recipe version=1
+
+// Pin the exact clean upstream tree this recipe transforms.
+source \
+    repo="https://github.com/arogozhnikov/einops.git" \
+    commit="ad2c8d67d08cbebb45e1aff2be21dc88635fc695"
+
+// Retain only the Python package and its upstream tests.
+prune keep="einops/**"
+
+// Lift upstream tests out of the package into the kernel test root.
+move \
+    from="einops/tests" \
+    to="tests"
+
+// Place the distributable package in the torch extension tree.
+move \
+    from="einops" \
+    to="torch-ext/einops"
+
+// Make package-internal imports work under the Hub-generated module name.
+relativize_imports \
+    in="torch-ext/einops/**" \
+    package_root="torch-ext/einops"
+
+// Expose array_api because Hub consumers cannot import it by package name.
+ensure_import \
+    in="torch-ext/einops/__init__.py" \
+    from="." \
+    name="array_api"
+
+// Point imports of the former einops.tests package at the lifted tests.
+remap_module \
+    in="tests/{__init__,test_*}.py" \
+    from="einops.tests" \
+    to="tests"
+
+// Make imports between lifted test modules package-relative.
+relativize_imports \
+    in="tests/{__init__,test_*}.py" \
+    package_root="tests"
+
+// Resolve product imports through the locally built Hub kernel. The package
+// init binds it privately so `from . import *` cannot pick it up.
+kernelize_imports \
+    in="tests/__init__.py" \
+    package="einops" \
+    binding="_einops" \
+    kernel="kernels-community/einops" \
+    version=1
+
+kernelize_imports \
+    in="tests/test_*.py" \
+    package="einops" \
+    kernel="kernels-community/einops" \
+    version=1
+
+// Default to Torch and NumPy tests, with an EINOPS_TEST_BACKENDS override.
+overlay from="overlay"
+
+// Use the supported replacement for NumPy 2's removed in1d API.
+replace in="tests/test_layers.py" \
+    find="numpy.in1d(grad, [0, 1])" \
+    with="numpy.isin(grad, [0, 1])"
+
+// Select every upstream test for the kernel CI suite.
+mark_tests in="tests/test_*.py" marker="kernels_ci" changes=63
+
+// Emit the noarch kernel manifest and supported runtime backends.
+manifest \
+    name="einops" \
+    version=1 \
+    edition=5 \
+    license="MIT" \
+    upstream="https://github.com/arogozhnikov/einops.git" \
+    backends="cpu,cuda,metal,rocm,xpu" \
+    repo_id="kernels-community/einops" \
+    noarch=#true
diff --git a/einops/build.toml b/einops/src/build.toml
similarity index 72%
rename from einops/build.toml
rename to einops/src/build.toml
index fcf94d562..5fd31b09b 100644
--- a/einops/build.toml
+++ b/einops/src/build.toml
@@ -4,7 +4,13 @@ version = 1
 edition = 5
 license = "MIT"
 upstream = "https://github.com/arogozhnikov/einops.git"
-backends = ["cpu", "cuda", "metal", "rocm", "xpu"]
+backends = [
+    "cpu",
+    "cuda",
+    "metal",
+    "rocm",
+    "xpu",
+]
 
 [general.hub]
 repo-id = "kernels-community/einops"
diff --git a/einops/src/port-provenance.json b/einops/src/port-provenance.json
new file mode 100644
index 000000000..c683484df
--- /dev/null
+++ b/einops/src/port-provenance.json
@@ -0,0 +1,12 @@
+{
+  "format": 1,
+  "recipe": "sha256:238127312e85c9489a67de689d3b2e59c75c456f6839afb640f344ef0e7965d5",
+  "runner": "kernel-port 0.1.0",
+  "sources": {
+    "upstream": {
+      "repo": "https://github.com/arogozhnikov/einops.git",
+      "commit": "ad2c8d67d08cbebb45e1aff2be21dc88635fc695"
+    }
+  },
+  "tree": "sha256:418031b9de86c73cadcf391017cb3f666fd816137449513b481f4af2caa6fe53"
+}
diff --git a/einops/tests/__init__.py b/einops/src/tests/__init__.py
similarity index 82%
rename from einops/tests/__init__.py
rename to einops/src/tests/__init__.py
index b8c629217..8972f0707 100644
--- a/einops/tests/__init__.py
+++ b/einops/src/tests/__init__.py
@@ -46,23 +46,15 @@ def unparse_backends(backend_names: List[str]) -> Tuple[str, str]:
 
 @lru_cache(maxsize=1)
 def parse_backends_to_test() -> List[str]:
-    if ENVVAR_NAME in os.environ:
-        parsed_backends = os.environ[ENVVAR_NAME].split(",")
-        _known_backends = find_names_of_all_frameworks()
-        for backend_name in parsed_backends:
-            if backend_name not in _known_backends:
-                raise RuntimeError(f"Unknown framework: {backend_name}")
-        return parsed_backends
-
-    # Auto-detect available frameworks.
-    available = []
-    for module, name in [("torch", "torch"), ("jax", "jax"), ("numpy", "numpy"), ("tensorflow", "tensorflow")]:
-        try:
-            __import__(module)
-            available.append(name)
-        except ImportError:
-            pass
-    return available
+    if ENVVAR_NAME not in os.environ:
+        raise RuntimeError(f"Testing frameworks were not specified, env var {ENVVAR_NAME} not set")
+    parsed_backends = os.environ[ENVVAR_NAME].split(",")
+    _known_backends = find_names_of_all_frameworks()
+    for backend_name in parsed_backends:
+        if backend_name not in _known_backends:
+            raise RuntimeError(f"Unknown framework: {backend_name}")
+
+    return parsed_backends
 
 
 def is_backend_tested(backend: str) -> bool:
diff --git a/einops/src/tests/conftest.py b/einops/src/tests/conftest.py
new file mode 100644
index 000000000..3fe86a864
--- /dev/null
+++ b/einops/src/tests/conftest.py
@@ -0,0 +1,4 @@
+import os
+
+# Use the CI backends by default, while allowing local overrides.
+os.environ.setdefault("EINOPS_TEST_BACKENDS", "torch,numpy")
diff --git a/einops/tests/run_tests.py b/einops/src/tests/run_tests.py
similarity index 100%
rename from einops/tests/run_tests.py
rename to einops/src/tests/run_tests.py
diff --git a/einops/tests/test_einsum.py b/einops/src/tests/test_einsum.py
similarity index 99%
rename from einops/tests/test_einsum.py
rename to einops/src/tests/test_einsum.py
index 2e05d939d..addf117b3 100644
--- a/einops/tests/test_einsum.py
+++ b/einops/src/tests/test_einsum.py
@@ -1,10 +1,10 @@
 from typing import Any, Callable
+from . import collect_test_backends
 import kernels
 einops = kernels.get_kernel("kernels-community/einops", version=1)
 _compactify_pattern_for_einsum = einops.einops._compactify_pattern_for_einsum
 einsum = einops.einops.einsum
-EinopsError = einops.EinopsError
-from . import collect_test_backends
+EinopsError = einops.einops.EinopsError
 import numpy as np
 import pytest
 import string
diff --git a/einops/tests/test_examples.py b/einops/src/tests/test_examples.py
similarity index 100%
rename from einops/tests/test_examples.py
rename to einops/src/tests/test_examples.py
diff --git a/einops/tests/test_layers.py b/einops/src/tests/test_layers.py
similarity index 99%
rename from einops/tests/test_layers.py
rename to einops/src/tests/test_layers.py
index 538b3b8e1..eab53c908 100644
--- a/einops/tests/test_layers.py
+++ b/einops/src/tests/test_layers.py
@@ -9,8 +9,7 @@
 rearrange = einops.rearrange
 reduce = einops.reduce
 EinopsError = einops.EinopsError
-from . import collect_test_backends, is_backend_tested
-from . import FLOAT_REDUCTIONS as REDUCTIONS
+from . import collect_test_backends, is_backend_tested, FLOAT_REDUCTIONS as REDUCTIONS
 
 __author__ = "Alex Rogozhnikov"
 
diff --git a/einops/tests/test_ops.py b/einops/src/tests/test_ops.py
similarity index 98%
rename from einops/tests/test_ops.py
rename to einops/src/tests/test_ops.py
index ff668bb50..1873524e1 100644
--- a/einops/tests/test_ops.py
+++ b/einops/src/tests/test_ops.py
@@ -11,8 +11,7 @@
 reduce = einops.einops.reduce
 repeat = einops.einops.repeat
 _enumerate_directions = einops.einops._enumerate_directions
-from . import collect_test_backends, is_backend_tested
-from . import FLOAT_REDUCTIONS as REDUCTIONS
+from . import collect_test_backends, is_backend_tested, FLOAT_REDUCTIONS as REDUCTIONS
 
 imp_op_backends = collect_test_backends(symbolic=False, layers=False)
 sym_op_backends = collect_test_backends(symbolic=True, layers=False)
@@ -370,10 +369,7 @@ def logsumexp_numpy(x, tuple_of_axes):
         y = numpy.sum(y, axis=tuple_of_axes)
         return numpy.log(y) + minused
 
-    TorchBackend = einops._backends.TorchBackend
-    TensorflowBackend = einops._backends.TensorflowBackend
-    TFKerasBackend = einops._backends.TFKerasBackend
-    NumpyBackend = einops._backends.NumpyBackend
+    TorchBackend, TensorflowBackend, TFKerasBackend, NumpyBackend = einops._backends.TorchBackend, einops._backends.TensorflowBackend, einops._backends.TFKerasBackend, einops._backends.NumpyBackend
 
     backend2callback = {
         TorchBackend.framework_name: logsumexp_torch,
diff --git a/einops/tests/test_other.py b/einops/src/tests/test_other.py
similarity index 100%
rename from einops/tests/test_other.py
rename to einops/src/tests/test_other.py
diff --git a/einops/tests/test_packing.py b/einops/src/tests/test_packing.py
similarity index 100%
rename from einops/tests/test_packing.py
rename to einops/src/tests/test_packing.py
diff --git a/einops/tests/test_parsing.py b/einops/src/tests/test_parsing.py
similarity index 100%
rename from einops/tests/test_parsing.py
rename to einops/src/tests/test_parsing.py
diff --git a/einops/torch-ext/einops/__init__.py b/einops/src/torch-ext/einops/__init__.py
similarity index 100%
rename from einops/torch-ext/einops/__init__.py
rename to einops/src/torch-ext/einops/__init__.py
diff --git a/einops/torch-ext/einops/_backends.py b/einops/src/torch-ext/einops/_backends.py
similarity index 100%
rename from einops/torch-ext/einops/_backends.py
rename to einops/src/torch-ext/einops/_backends.py
diff --git a/einops/torch-ext/einops/_torch_specific.py b/einops/src/torch-ext/einops/_torch_specific.py
similarity index 100%
rename from einops/torch-ext/einops/_torch_specific.py
rename to einops/src/torch-ext/einops/_torch_specific.py
diff --git a/einops/torch-ext/einops/array_api.py b/einops/src/torch-ext/einops/array_api.py
similarity index 100%
rename from einops/torch-ext/einops/array_api.py
rename to einops/src/torch-ext/einops/array_api.py
diff --git a/einops/torch-ext/einops/einops.py b/einops/src/torch-ext/einops/einops.py
similarity index 100%
rename from einops/torch-ext/einops/einops.py
rename to einops/src/torch-ext/einops/einops.py
diff --git a/einops/torch-ext/einops/experimental/__init__.py b/einops/src/torch-ext/einops/experimental/__init__.py
similarity index 100%
rename from einops/torch-ext/einops/experimental/__init__.py
rename to einops/src/torch-ext/einops/experimental/__init__.py
diff --git a/einops/torch-ext/einops/experimental/indexing.py b/einops/src/torch-ext/einops/experimental/indexing.py
similarity index 100%
rename from einops/torch-ext/einops/experimental/indexing.py
rename to einops/src/torch-ext/einops/experimental/indexing.py
diff --git a/einops/torch-ext/einops/layers/__init__.py b/einops/src/torch-ext/einops/layers/__init__.py
similarity index 100%
rename from einops/torch-ext/einops/layers/__init__.py
rename to einops/src/torch-ext/einops/layers/__init__.py
diff --git a/einops/torch-ext/einops/layers/_einmix.py b/einops/src/torch-ext/einops/layers/_einmix.py
similarity index 100%
rename from einops/torch-ext/einops/layers/_einmix.py
rename to einops/src/torch-ext/einops/layers/_einmix.py
diff --git a/einops/torch-ext/einops/layers/flax.py b/einops/src/torch-ext/einops/layers/flax.py
similarity index 100%
rename from einops/torch-ext/einops/layers/flax.py
rename to einops/src/torch-ext/einops/layers/flax.py
diff --git a/einops/torch-ext/einops/layers/keras.py b/einops/src/torch-ext/einops/layers/keras.py
similarity index 100%
rename from einops/torch-ext/einops/layers/keras.py
rename to einops/src/torch-ext/einops/layers/keras.py
diff --git a/einops/torch-ext/einops/layers/oneflow.py b/einops/src/torch-ext/einops/layers/oneflow.py
similarity index 100%
rename from einops/torch-ext/einops/layers/oneflow.py
rename to einops/src/torch-ext/einops/layers/oneflow.py
diff --git a/einops/torch-ext/einops/layers/paddle.py b/einops/src/torch-ext/einops/layers/paddle.py
similarity index 100%
rename from einops/torch-ext/einops/layers/paddle.py
rename to einops/src/torch-ext/einops/layers/paddle.py
diff --git a/einops/torch-ext/einops/layers/tensorflow.py b/einops/src/torch-ext/einops/layers/tensorflow.py
similarity index 100%
rename from einops/torch-ext/einops/layers/tensorflow.py
rename to einops/src/torch-ext/einops/layers/tensorflow.py
diff --git a/einops/torch-ext/einops/layers/torch.py b/einops/src/torch-ext/einops/layers/torch.py
similarity index 100%
rename from einops/torch-ext/einops/layers/torch.py
rename to einops/src/torch-ext/einops/layers/torch.py
diff --git a/einops/torch-ext/einops/packing.py b/einops/src/torch-ext/einops/packing.py
similarity index 100%
rename from einops/torch-ext/einops/packing.py
rename to einops/src/torch-ext/einops/packing.py
diff --git a/einops/torch-ext/einops/parsing.py b/einops/src/torch-ext/einops/parsing.py
similarity index 100%
rename from einops/torch-ext/einops/parsing.py
rename to einops/src/torch-ext/einops/parsing.py
diff --git a/einops/torch-ext/einops/py.typed b/einops/src/torch-ext/einops/py.typed
similarity index 100%
rename from einops/torch-ext/einops/py.typed
rename to einops/src/torch-ext/einops/py.typed
diff --git a/scripts/check_ports.py b/scripts/check_ports.py
new file mode 100644
index 000000000..d6dd27644
--- /dev/null
+++ b/scripts/check_ports.py
@@ -0,0 +1,165 @@
+#!/usr/bin/env python3
+import filecmp
+import os
+import re
+import shlex
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+# Extract source arguments; kernel-port validates them.
+SOURCE_RE = re.compile(
+    r"^source\b(?P<body>(?:[^\n\\]|\\\s*\n)*)", re.MULTILINE
+)
+ARG_RE = re.compile(r'(\w+)="([^"]*)"')
+
+DEFAULT_RUNNER = "kernel-port"
+
+CHECKER_FILES = {"scripts/check_ports.py", ".github/workflows/check-ports.yaml"}
+
+
+def runner_cmd() -> list:
+    return shlex.split(os.environ.get("KERNEL_PORT", DEFAULT_RUNNER))
+
+
+def find_ports(root: Path) -> list:
+    return sorted(p.parent.parent.name for p in root.glob("*/port/port.kdl"))
+
+
+def changed_ports(root: Path, ref: str) -> list:
+    """Select changed ports, or all ports when the checker or workflow changes."""
+    out = subprocess.run(
+        ["git", "diff", "--name-only", f"{ref}...HEAD"],
+        capture_output=True,
+        text=True,
+        check=True,
+    ).stdout
+    touched = set()
+    for line in out.splitlines():
+        if line in CHECKER_FILES:
+            return find_ports(root)
+        parts = line.split("/")
+        if len(parts) >= 3 and parts[1] in ("port", "src"):
+            touched.add(parts[0])
+    return sorted(k for k in find_ports(root) if k in touched)
+
+
+def parse_source(recipe: Path) -> tuple:
+    text = recipe.read_text()
+    m = SOURCE_RE.search(text)
+    if not m:
+        raise SystemExit(f"{recipe}: no `source` op found")
+    args = dict(ARG_RE.findall(m.group("body").replace("\\\n", " ")))
+    try:
+        return args["repo"], args["commit"]
+    except KeyError as exc:
+        raise SystemExit(f"{recipe}: source is missing {exc}") from exc
+
+
+def checkout(repo: str, commit: str, dest: Path) -> None:
+    subprocess.run(
+        ["git", "clone", "--quiet", "--filter=blob:none", "--no-checkout", repo, str(dest)],
+        check=True,
+    )
+    subprocess.run(["git", "-C", str(dest), "checkout", "--quiet", commit], check=True)
+
+
+def tree_files(root: Path) -> set:
+    return {
+        p.relative_to(root).as_posix()
+        for p in root.rglob("*")
+        if p.is_file() and "__pycache__" not in p.parts
+    }
+
+
+def compare(generated: Path, committed: Path) -> list:
+    gen, com = tree_files(generated), tree_files(committed)
+    problems = []
+    for rel in sorted(com - gen):
+        problems.append(f"committed but not generated: {rel}")
+    for rel in sorted(gen - com):
+        problems.append(f"generated but not committed: {rel}")
+    for rel in sorted(gen & com):
+        if not filecmp.cmp(generated / rel, committed / rel, shallow=False):
+            problems.append(f"differs: {rel}")
+    return problems
+
+
+def check(kernel: str, root: Path, workdir: Path) -> list:
+    recipe = root / kernel / "port" / "port.kdl"
+    repo, commit = parse_source(recipe)
+    print(f"  {kernel}: {repo} @ {commit[:12]}")
+
+    # Reuse checkouts for kernels sharing an upstream commit.
+    src = workdir / f"upstream-{commit[:12]}"
+    if not src.exists():
+        checkout(repo, commit, src)
+
+    out = workdir / f"out-{kernel}"
+    shutil.rmtree(out, ignore_errors=True)
+    proc = subprocess.run(
+        [*runner_cmd(), str(recipe), "--dir", str(src), "--out", str(out)],
+        capture_output=True,
+        text=True,
+    )
+    if proc.returncode != 0:
+        tail = (proc.stderr or proc.stdout).strip().splitlines()[-8:]
+        return [f"kernel-port failed:\n    " + "\n    ".join(tail)]
+
+    return compare(out, root / kernel / "src")
+
+
+def main() -> int:
+    root = Path.cwd()
+    args = sys.argv[1:]
+    if args[:1] == ["--changed-since"]:
+        if len(args) != 2:
+            raise SystemExit("usage: check_ports.py --changed-since <ref>")
+        kernels = changed_ports(root, args[1])
+        if not kernels:
+            print(f"No ported kernels changed since {args[1]}.")
+            return 0
+    else:
+        kernels = args or find_ports(root)
+    if not kernels:
+        print("No ported kernels found (no */port/port.kdl).")
+        return 0
+
+    print(f"Checking {len(kernels)} port(s) reproduce their committed tree:\n")
+    failed = {}
+    with tempfile.TemporaryDirectory() as tmp:
+        workdir = Path(tmp)
+        for kernel in kernels:
+            if not (root / kernel / "port" / "port.kdl").is_file():
+                failed[kernel] = [f"no port/port.kdl under {kernel}/"]
+                continue
+            problems = check(kernel, root, workdir)
+            if problems:
+                failed[kernel] = problems
+            else:
+                print("     ok - regenerates byte for byte")
+
+    if failed:
+        print("\nERROR: committed tree does not match the recipe.\n", file=sys.stderr)
+        for kernel, problems in failed.items():
+            print(f"  {kernel}:", file=sys.stderr)
+            for p in problems:
+                print(f"    - {p}", file=sys.stderr)
+        print(
+            "\nRegenerate with:\n"
+            "  kernel-port <kernel>/port/port.kdl --dir <upstream> --out <kernel>/src\n"
+            "If an overlay file went stale, refresh it from <kernel>/src first.\n"
+            "If only port-provenance.json differs, the recipe changed and the\n"
+            "port was not rerun.",
+            file=sys.stderr,
+        )
+        return 1
+
+    print("\nAll ports reproduce their committed tree.")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/scripts/run_kernels_checks.py b/scripts/run_kernels_checks.py
index 39a75b2e1..ca854d43c 100644
--- a/scripts/run_kernels_checks.py
+++ b/scripts/run_kernels_checks.py
@@ -57,7 +57,10 @@ def discover_kernel_dirs(root: Path, excludes: list[str]) -> list[str]:
         name = entry.name
         if name in filtered:
             continue
-        elif entry.is_dir() and not (entry / "build.toml").exists():
+        # Ported kernels keep build.toml in <kernel>/src.
+        elif entry.is_dir() and not (
+            (entry / "build.toml").exists() or (entry / "src" / "build.toml").exists()
+        ):
             logging.debug(f"Skipping {name} because it doesn't contain a `build.toml`.")
             continue
         if entry.is_dir():