diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index a5507a9..83fdce8 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,7 +13,14 @@ concurrency:
 
 jobs:
   validate:
-    runs-on: macos-latest
+    name: Validate (${{ matrix.os }})
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - macos-latest
+          - ubuntu-latest
+    runs-on: ${{ matrix.os }}
     timeout-minutes: 10
     steps:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
@@ -27,3 +34,43 @@ jobs:
         run: python -m pip install ".[dev]"
       - name: Run Python tests
         run: python -m pytest
+
+  linux-distributions:
+    name: Validate (${{ matrix.name }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: Debian 12
+            image: debian:12-slim
+            family: debian
+          - name: Fedora latest
+            image: fedora:latest
+            family: fedora
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Run distribution validation in Docker
+        env:
+          DISTRO_IMAGE: ${{ matrix.image }}
+          DISTRO_FAMILY: ${{ matrix.family }}
+        run: |
+          docker run --rm \
+            --volume "$GITHUB_WORKSPACE:/workspace" \
+            --workdir /workspace \
+            --env DISTRO_FAMILY \
+            "$DISTRO_IMAGE" \
+            sh -lc '
+              set -eu
+              if [ "$DISTRO_FAMILY" = debian ]; then
+                apt-get update
+                DEBIAN_FRONTEND=noninteractive apt-get install -y bash python3 python3-pip python3-venv
+              else
+                dnf install -y python3 python3-pip
+              fi
+              ./tests/validate.sh
+              python3 -m venv /tmp/base-cli-venv
+              /tmp/base-cli-venv/bin/python -m pip install ".[dev]"
+              /tmp/base-cli-venv/bin/python -m pytest
+              /tmp/base-cli-venv/bin/python -c "import base_cli; print(base_cli.__version__)"
+            '
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9603a75..b16f056 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and versions are tracked in the repo-root `VERSION` file.
   locking backends.
 - Make terminal detection tolerate closed streams and record `COMSPEC` when
   Windows has no `SHELL` environment variable.
+- Add Linux distribution and WSL2 validation guidance for the generic package.
 
 ## [0.2.0] - 2026-08-01
 
diff --git a/docs/platform-support.md b/docs/platform-support.md
new file mode 100644
index 0000000..3841e9d
--- /dev/null
+++ b/docs/platform-support.md
@@ -0,0 +1,27 @@
+# Platform support
+
+`base-cli` is a pure-Python framework. Its Linux support is distribution-neutral
+and is validated on Ubuntu, Debian, and Fedora-family environments. The
+package does not install or manage operating-system packages; consumers remain
+responsible for Python and any external tools their commands need.
+
+## WSL2
+
+WSL2 is supported when Python runs inside the Linux distribution. Validate a
+checkout from the WSL shell with:
+
+```bash
+python3 -m venv .venv
+.venv/bin/python -m pip install --upgrade pip
+.venv/bin/python -m pip install ".[dev]"
+.venv/bin/python -m pytest
+```
+
+Prefer a checkout in the WSL filesystem (for example, under `~/work`) for
+normal development. Windows-mounted paths such as `/mnt/c` remain usable, but
+their filesystem performance, case-sensitivity, and permission behavior are
+provided by the Windows mount and are outside the Linux filesystem contract.
+
+WSL2 support does not imply that the generic package translates paths between
+Linux and Windows or that a consumer's native Windows commands are available
+inside the distribution.
diff --git a/tests/test_app_runtime_errors.py b/tests/test_app_runtime_errors.py
index bc55dfa..2e2354d 100644
--- a/tests/test_app_runtime_errors.py
+++ b/tests/test_app_runtime_errors.py
@@ -42,7 +42,7 @@ def main(ctx: base_cli.Context) -> None:
                 invoke(app, [])
 
     @unittest.skipUnless(importlib.util.find_spec("click"), "Click is not installed")
-    def test_run_app_reports_unwritable_cache_root_without_traceback(self) -> None:
+    def test_run_app_reports_unusable_cache_root_without_traceback(self) -> None:
         app = generic_app(name="cache-failure", version="0.1.0")
 
         @app.command()
@@ -55,18 +55,17 @@ def main(ctx: base_cli.Context) -> None:
             home = root / "home"
             cache_root = root / "cache-root"
             home.mkdir()
-            cache_root.mkdir()
-            cache_root.chmod(0o500)
+            # A regular file is unusable as a cache root on every platform and
+            # also behaves consistently when the test suite runs as root in a
+            # Linux distribution container (where mode bits are bypassed).
+            cache_root.write_text("not a directory", encoding="utf-8")
             stderr = io.StringIO()
-            try:
-                with mock.patch.dict(os.environ, {"HOME": str(home), "BASE_CLI_CACHE_DIR": str(cache_root)}):
-                    with redirect_stderr(stderr):
-                        try:
-                            exit_code = base_cli.run_app(app, [])
-                        except PermissionError as exc:
-                            self.fail(f"run_app should handle context creation permission errors: {exc}")
-            finally:
-                cache_root.chmod(0o700)
+            with mock.patch.dict(os.environ, {"HOME": str(home), "BASE_CLI_CACHE_DIR": str(cache_root)}):
+                with redirect_stderr(stderr):
+                    try:
+                        exit_code = base_cli.run_app(app, [])
+                    except PermissionError as exc:
+                        self.fail(f"run_app should handle context creation permission errors: {exc}")
 
         error = stderr.getvalue()
         self.assertEqual(exit_code, 1)