diff --git a/.github/dependabot.yml b/.github/dependabot.yml
new file mode 100644
index 0000000..e684638
--- /dev/null
+++ b/.github/dependabot.yml
@@ -0,0 +1,14 @@
+version: 2
+updates:
+  # Actions are pinned by commit SHA (tests/test_workflow_action_pins.py), which
+  # is only safe if something moves the pins: an action nobody bumps stops
+  # receiving its own security fixes, and the pin hides that it has gone stale.
+  # Grouped so this arrives as one pull request a week rather than fifteen.
+  - package-ecosystem: github-actions
+    directory: /
+    schedule:
+      interval: weekly
+    groups:
+      github-actions:
+        patterns:
+          - '*'
diff --git a/.github/workflows/codeberg-mirror.yml b/.github/workflows/codeberg-mirror.yml
index 38edc3b..3c3438a 100644
--- a/.github/workflows/codeberg-mirror.yml
+++ b/.github/workflows/codeberg-mirror.yml
@@ -17,7 +17,7 @@ jobs:
     runs-on: ubuntu-latest
     if: github.repository == 'VocaHQ/vocalinux'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
         with:
           fetch-depth: 0
 
diff --git a/.github/workflows/distro-test-matrix.yml b/.github/workflows/distro-test-matrix.yml
index 4f5c4f9..0f11e15 100644
--- a/.github/workflows/distro-test-matrix.yml
+++ b/.github/workflows/distro-test-matrix.yml
@@ -37,7 +37,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Install basic dependencies
         run: |
diff --git a/.github/workflows/flatpak.yml b/.github/workflows/flatpak.yml
index ef0ac28..f98bf62 100644
--- a/.github/workflows/flatpak.yml
+++ b/.github/workflows/flatpak.yml
@@ -51,10 +51,10 @@ jobs:
       options: --privileged
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Build and bundle
-        uses: flatpak/flatpak-github-actions/flatpak-builder@v6
+        uses: flatpak/flatpak-github-actions/flatpak-builder@79327416609af08178ad73b352877e51450790b3 # v6
         with:
           bundle: vocalinux-${{ matrix.arch }}.flatpak
           manifest-path: packaging/flatpak/com.vocalinux.Vocalinux.yml
diff --git a/.github/workflows/issue-welcome.yml b/.github/workflows/issue-welcome.yml
index 73cdf94..6621de5 100644
--- a/.github/workflows/issue-welcome.yml
+++ b/.github/workflows/issue-welcome.yml
@@ -13,4 +13,8 @@ permissions:
 
 jobs:
   welcome:
+    # Deliberately unpinned: this is our own org's shared workflow, inside the
+    # same trust boundary as this repository, and the point of it is that a
+    # change to the welcome text reaches every VocaHQ repo without 30 bumps.
+    # Everything third-party is pinned by SHA (tests/test_workflow_action_pins.py).
     uses: VocaHQ/.github/.github/workflows/issue-welcome.yml@main
diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
index f0375f4..6220379 100644
--- a/.github/workflows/labeler.yml
+++ b/.github/workflows/labeler.yml
@@ -12,7 +12,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Label PR
-        uses: actions/labeler@v6
+        uses: actions/labeler@b8dd2d9be0f68b860e7dae5dae7d772984eacd6d # v6
         with:
           repo-token: "${{ secrets.GITHUB_TOKEN }}"
           sync-labels: true
diff --git a/.github/workflows/nightly.yml b/.github/workflows/nightly.yml
index eacaca9..b51635c 100644
--- a/.github/workflows/nightly.yml
+++ b/.github/workflows/nightly.yml
@@ -18,13 +18,13 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
         with:
           ref: main
           fetch-depth: 0
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: '3.11'
           cache: 'pip'
@@ -67,7 +67,7 @@ jobs:
       # glslc is built from the pinned shaderc commit inside the container -
       # Ubuntu 22.04 packages none - and depends on nothing but that commit.
       - name: Cache AppImage build tools
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.cache/vocalinux-appimage
           key: appimage-tools-${{ runner.arch }}-${{ hashFiles('packaging/appimage/tool_checksums.txt') }}
@@ -232,7 +232,7 @@ jobs:
           echo "tag=${RELEASE_TAG}" >> "$GITHUB_OUTPUT"
 
       - name: Upload artifacts (backup)
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: vocalinux-nightly-${{ steps.version.outputs.version }}
           path: dist/
@@ -246,12 +246,12 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
         with:
           ref: main
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: '3.11'
           cache: 'pip'
@@ -278,7 +278,7 @@ jobs:
       # glslc is built from the pinned shaderc commit inside the container -
       # Ubuntu 22.04 packages none - and depends on nothing but that commit.
       - name: Cache AppImage build tools
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.cache/vocalinux-appimage
           key: appimage-tools-${{ runner.arch }}-${{ hashFiles('packaging/appimage/tool_checksums.txt') }}
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 5ce5722..1ca4895 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -5,10 +5,11 @@ on:
     tags:
       - 'v*'
 
+# Least privilege, granted per job. `id-token: write` at the top level handed an
+# OIDC token to every job in the workflow, including publish-aur, which runs a
+# third-party action with our AUR signing key.
 permissions:
-  contents: write
-  packages: write
-  id-token: write  # Required for PyPI trusted publishing
+  contents: read
 
 env:
   # Build against the supported floor (requires-python in pyproject.toml).
@@ -18,14 +19,16 @@ jobs:
   build-and-release:
     name: Build and Create Release
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
         with:
           fetch-depth: 0
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
           cache: 'pip'
@@ -33,7 +36,7 @@ jobs:
       - name: Install build dependencies
         run: |
           python -m pip install --upgrade pip
-          pip install build twine wheel setuptools
+          pip install build wheel setuptools
 
       - name: Extract version from tag
         id: get_version
@@ -54,16 +57,37 @@ jobs:
             echo "Warning: Version mismatch between tag ($TAG_VERSION) and package ($PACKAGE_VERSION)"
           fi
 
+      # Archive timestamps are what made two builds of one tag differ. Pinned to
+      # the tagged commit, re-running this workflow reproduces the bytes we
+      # published, so a checksum stays true for the life of the release.
+      - name: Pin the build timestamp to the tagged commit
+        run: |
+          echo "SOURCE_DATE_EPOCH=$(git log -1 --format=%ct "$GITHUB_SHA")" >> "$GITHUB_ENV"
+
+      # The only `python -m build` in this workflow. PyPI, the aarch64 AppImage
+      # and the checksums all consume the artifact below, so the wheel on PyPI
+      # is the wheel on the release. It used to be built three times, on three
+      # runners, and nothing guaranteed the three agreed.
       - name: Build package
         run: |
           python -m build
           echo "Built packages:"
           ls -la dist/
 
+      - name: Upload the built distributions
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: python-dist
+          path: |
+            dist/*.whl
+            dist/*.tar.gz
+          if-no-files-found: error
+          retention-days: 7
+
       # glslc is built from the pinned shaderc commit inside the container -
       # Ubuntu 22.04 packages none - and depends on nothing but that commit.
       - name: Cache AppImage build tools
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.cache/vocalinux-appimage
           key: appimage-tools-${{ runner.arch }}-${{ hashFiles('packaging/appimage/tool_checksums.txt') }}
@@ -75,9 +99,17 @@ jobs:
           bash packaging/appimage/docker-build.sh dist/*.whl "${{ steps.get_version.outputs.VERSION }}" dist
           ls -la dist/*.AppImage
 
+      - name: Upload the x86_64 AppImage
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: appimage-x86_64
+          path: dist/*.AppImage
+          if-no-files-found: error
+          retention-days: 7
+
       - name: Create Release
         id: create_release
-        uses: softprops/action-gh-release@v2
+        uses: softprops/action-gh-release@3bb12739c298aeb8a4eeaf626c5b8d85266b0e65 # v2
         with:
           files: |
             dist/*.whl
@@ -129,6 +161,19 @@ jobs:
             ```
             Still requires `xdotool`/`wtype`/`ydotool` on the host for text injection, same as the PyPI path.
 
+            ### Verifying what you downloaded
+            `SHA256SUMS` covers every file here and is attached once the aarch64 build finishes,
+            a few minutes after this release appears. The wheel and sdist below are the same bytes
+            published to PyPI.
+            ```bash
+            sha256sum -c --ignore-missing SHA256SUMS
+            ```
+            Each artifact also carries GitHub build provenance, which ties it to this workflow run:
+            ```bash
+            gh attestation verify Vocalinux-${{ steps.get_version.outputs.VERSION }}-x86_64.AppImage \
+              --repo ${{ github.repository }}
+            ```
+
             ---
             See [CHANGELOG](https://github.com/VocaHQ/vocalinux/releases) for detailed changes.
 
@@ -136,20 +181,11 @@ jobs:
     name: Build and Attach AppImage (aarch64)
     needs: build-and-release
     runs-on: ubuntu-24.04-arm
+    permissions:
+      contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
-
-      - name: Set up Python
-        uses: actions/setup-python@v5
-        with:
-          python-version: ${{ env.PYTHON_VERSION }}
-          cache: 'pip'
-
-      - name: Install build dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install build wheel setuptools
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Extract version from tag
         id: get_version
@@ -157,15 +193,19 @@ jobs:
           VERSION=${GITHUB_REF#refs/tags/v}
           echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
 
-      - name: Build package
-        run: |
-          python -m build
-          ls -la dist/
+      # The wheel is py3-none-any, so this is the wheel the release and PyPI
+      # carry. Building it again here made a third copy of the same version that
+      # no published checksum could describe.
+      - name: Download the built distributions
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
+        with:
+          name: python-dist
+          path: dist
 
       # glslc is built from the pinned shaderc commit inside the container -
       # Ubuntu 22.04 packages none - and depends on nothing but that commit.
       - name: Cache AppImage build tools
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.cache/vocalinux-appimage
           key: appimage-tools-${{ runner.arch }}-${{ hashFiles('packaging/appimage/tool_checksums.txt') }}
@@ -177,6 +217,14 @@ jobs:
           bash packaging/appimage/docker-build.sh dist/*.whl "${{ steps.get_version.outputs.VERSION }}" dist
           ls -la dist/*.AppImage
 
+      - name: Upload the aarch64 AppImage
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+        with:
+          name: appimage-aarch64
+          path: dist/*.AppImage
+          if-no-files-found: error
+          retention-days: 7
+
       - name: Attach to release
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -186,49 +234,89 @@ jobs:
             --repo ${{ github.repository }} \
             --clobber
 
+  # Runs last because the aarch64 AppImage lands after the release is created:
+  # a checksum manifest that covers three of the four files is worse than none,
+  # since the missing one looks like the tampered one.
+  publish-checksums:
+    name: Checksums and Provenance
+    needs: [build-and-release, build-appimage-arm64]
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      id-token: write
+      attestations: write
+    steps:
+      - name: Collect every artifact this run published
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
+        with:
+          merge-multiple: true
+          path: dist
+
+      - name: Generate SHA256SUMS
+        working-directory: dist
+        run: |
+          set -euo pipefail
+          ls -la
+          # Bare names, so `sha256sum -c` works in whatever directory the user
+          # downloaded the release into.
+          sha256sum -- *.whl *.tar.gz *.AppImage | tee SHA256SUMS
+
+      # Attesting from the manifest rather than a second glob: the file we
+      # publish and the set we attest cannot drift apart.
+      - name: Attest build provenance
+        uses: actions/attest-build-provenance@4d101475d8b20a2381f78447822ac1eab6504dd8 # v4
+        with:
+          subject-checksums: dist/SHA256SUMS
+
+      - name: Attach SHA256SUMS to the release
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          gh release upload "${{ github.ref_name }}" \
+            dist/SHA256SUMS \
+            --repo ${{ github.repository }} \
+            --clobber
+
   publish-pypi:
     name: Publish to PyPI
     needs: build-and-release
     runs-on: ubuntu-latest
+    permissions:
+      id-token: write  # PyPI trusted publishing; there is no API token to leak
     environment:
       name: pypi
       url: https://pypi.org/project/vocalinux/
     steps:
-      - name: Checkout code
-        uses: actions/checkout@v5
+      # Not a rebuild: the artifact attached to the GitHub release, so one
+      # checksum describes both.
+      - name: Download the built distributions
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
+        with:
+          name: python-dist
+          path: dist
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: ${{ env.PYTHON_VERSION }}
-          cache: 'pip'
-
-      - name: Install build dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install build twine
-
-      - name: Build package
-        run: |
-          python -m build
-          echo "Built packages:"
-          ls -la dist/
 
       - name: Verify package
         run: |
+          python -m pip install --upgrade pip
+          pip install twine
           twine check dist/*
 
       - name: Publish to PyPI
-        env:
-          TWINE_USERNAME: __token__
-          TWINE_PASSWORD: ${{ secrets.PYPI_API_TOKEN }}
-        run: |
-          twine upload dist/* --skip-existing
+        uses: pypa/gh-action-pypi-publish@dc37677b2e1c63e2034f94d8a5b11f265b73ba33 # release/v1
+        with:
+          skip-existing: true
 
   publish-aur:
     name: Publish to AUR
     needs: build-and-release
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     # Secrets: AUR_SSH_PRIVATE_KEY, AUR_USERNAME, AUR_EMAIL — see docs/AUR.md
     steps:
       - name: Check for AUR credentials
@@ -245,7 +333,7 @@ jobs:
 
       - name: Checkout code
         if: steps.aur.outputs.configured == 'true'
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Bump PKGBUILD version
         if: steps.aur.outputs.configured == 'true'
@@ -258,7 +346,7 @@ jobs:
 
       - name: Publish AUR package
         if: steps.aur.outputs.configured == 'true'
-        uses: KSXGitHub/github-actions-deploy-aur@v4.2.0
+        uses: KSXGitHub/github-actions-deploy-aur@084b0d9b15415bf9cdb65d44dad1efe37a354050 # v4.2.0
         with:
           pkgname: vocalinux
           pkgbuild: packaging/aur/vocalinux/PKGBUILD
@@ -272,12 +360,14 @@ jobs:
     name: Deploy Website
     runs-on: ubuntu-latest
     needs: [build-and-release, publish-pypi]
+    permissions:
+      contents: write
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Setup Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
         with:
           node-version: '24'
           cache: 'npm'
@@ -319,7 +409,7 @@ jobs:
           npm run deploy
 
       - name: Deploy to gh-pages
-        uses: peaceiris/actions-gh-pages@v4
+        uses: peaceiris/actions-gh-pages@84c30a85c19949d7eee79c4ff27748b70285e453 # v4
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./web/out
diff --git a/.github/workflows/unified-pipeline.yml b/.github/workflows/unified-pipeline.yml
index 0e681f4..2646e65 100644
--- a/.github/workflows/unified-pipeline.yml
+++ b/.github/workflows/unified-pipeline.yml
@@ -25,8 +25,8 @@ jobs:
       python: ${{ steps.filter.outputs.python }}
       deploy_website: ${{ steps.deploy_check.outputs.deploy }}
     steps:
-      - uses: actions/checkout@v5
-      - uses: dorny/paths-filter@v3
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
+      - uses: dorny/paths-filter@0e4a8c6effa4802afeda77dc8d303f8176d7dfad # v3
         id: filter
         with:
           filters: |
@@ -79,10 +79,10 @@ jobs:
     needs: changes
     if: needs.changes.outputs.python == 'true'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Set up uv
-        uses: astral-sh/setup-uv@v6
+        uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6
         with:
           enable-cache: true
 
@@ -116,10 +116,10 @@ jobs:
         python-version: ['3.11', '3.12', '3.13', '3.14']
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Set up uv
-        uses: astral-sh/setup-uv@v6
+        uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6
         with:
           enable-cache: true
           python-version: ${{ matrix.python-version }}
@@ -162,14 +162,14 @@ jobs:
 
       - name: Upload test results
         if: always()
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: test-results-${{ matrix.python-version }}
           path: junit-${{ matrix.python-version }}.xml
 
       - name: Upload coverage to Codecov
         if: matrix.python-version == '3.13'
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@b9fd7d16f6d7d1b5d2bec1a2887e65ceed900238 # v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           files: coverage.xml
@@ -182,10 +182,10 @@ jobs:
     needs: [changes, python-lint]
     if: needs.changes.outputs.python == 'true'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Set up uv
-        uses: astral-sh/setup-uv@v6
+        uses: astral-sh/setup-uv@d0cc045d04ccac9d8b7881df0226f9e82c39688e # v6
         with:
           # Caches uv's download cache, not .venv/, so the checkout below stays
           # the fresh clone this job exists to exercise.
@@ -231,10 +231,10 @@ jobs:
           - arch: aarch64
             runner: ubuntu-24.04-arm
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
         with:
           python-version: '3.11'
           cache: 'pip'
@@ -248,7 +248,7 @@ jobs:
       # glslc is built from the pinned shaderc commit inside the container -
       # Ubuntu 22.04 packages none - and depends on nothing but that commit.
       - name: Cache AppImage build tools
-        uses: actions/cache@v4
+        uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
         with:
           path: ~/.cache/vocalinux-appimage
           key: appimage-tools-${{ matrix.arch }}-${{ hashFiles('packaging/appimage/tool_checksums.txt') }}
@@ -263,7 +263,7 @@ jobs:
           ls -la dist/*.AppImage
 
       - name: Upload AppImage artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: vocalinux-appimage-${{ matrix.arch }}
           path: dist/*.AppImage
@@ -289,10 +289,10 @@ jobs:
           - archlinux:latest
           - opensuse/tumbleweed
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Download the AppImage built above
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
         with:
           name: vocalinux-appimage-x86_64
           path: dist
@@ -313,10 +313,10 @@ jobs:
     needs: changes
     if: needs.changes.outputs.deploy_website == 'true'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Setup Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
         with:
           node-version: '24'
           cache: 'npm'
@@ -371,10 +371,10 @@ jobs:
       needs.changes.outputs.deploy_website == 'true' &&
       needs.web-build.result == 'success'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@fbc6f3992d24b796d5a048ff273f7fcc4a7b6c09 # v5
 
       - name: Setup Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@a0853c24544627f65ddf259abe73b1d18a591444 # v5
         with:
           node-version: '24'
           cache: 'npm'
@@ -387,7 +387,7 @@ jobs:
           npm run deploy
 
       - name: Deploy to gh-pages
-        uses: peaceiris/actions-gh-pages@v4
+        uses: peaceiris/actions-gh-pages@84c30a85c19949d7eee79c4ff27748b70285e453 # v4
         with:
           github_token: ${{ secrets.GITHUB_TOKEN }}
           publish_dir: ./web/out
diff --git a/docs/RELEASE_PROCESS.md b/docs/RELEASE_PROCESS.md
index aba0c96..184f0d6 100644
--- a/docs/RELEASE_PROCESS.md
+++ b/docs/RELEASE_PROCESS.md
@@ -10,6 +10,33 @@ Vocalinux uses [Semantic Versioning](https://semver.org/) with pre-release suffi
 - **RC** (Release Candidate): Final testing before stable (e.g., `0.5.0-rc1`)
 - **Stable**: Production-ready (e.g., `1.0.0`)
 
+## Release Infrastructure (one-time setup)
+
+These are configured once per repository. A tag pushed before they exist will fail
+in the corresponding job.
+
+### PyPI trusted publishing (required)
+
+`publish-pypi` authenticates with a short-lived OIDC token instead of a stored API
+token, so there is no `PYPI_API_TOKEN` secret to leak or rotate. It only works once
+PyPI knows about this workflow. On https://pypi.org/manage/project/vocalinux/settings/publishing/
+add a GitHub publisher:
+
+| field | value |
+|---|---|
+| Owner | `VocaHQ` |
+| Repository | `vocalinux` |
+| Workflow name | `release.yml` |
+| Environment | `pypi` |
+
+Until that publisher exists, `publish-pypi` fails with `invalid-publisher`. The old
+`PYPI_API_TOKEN` secret can be deleted from the repository once the first trusted
+publish succeeds.
+
+### AUR (optional)
+
+`publish-aur` skips itself when `AUR_SSH_PRIVATE_KEY` is unset. See docs/AUR.md.
+
 ## Quick Release Checklist
 
 Use this checklist for every release:
@@ -350,20 +377,29 @@ git push origin v0.5.0-beta
 
 After pushing the tag, the GitHub Actions workflow will automatically:
 
-1. Build the Python package (wheel and sdist)
-2. Build and attach AppImages for x86_64 and aarch64
+1. Build the Python package (wheel and sdist) — **once**, with `SOURCE_DATE_EPOCH`
+   pinned to the tagged commit. Every later job downloads that artifact instead of
+   rebuilding, so the wheel on PyPI is byte-for-byte the wheel on the release
+2. Build and attach AppImages for x86_64 and aarch64, both from that same wheel
 3. Create a GitHub Release with auto-generated notes
-4. Publish to PyPI
-5. Publish the AUR package (when the `AUR_SSH_PRIVATE_KEY` secret is configured)
-6. Deploy the website to vocalinux.com
-7. Mark as pre-release if version contains alpha/beta/rc
+4. Attach `SHA256SUMS` covering all four artifacts, and generate build provenance
+   attestations from that manifest (runs after the aarch64 AppImage lands, so a
+   partial manifest never gets published)
+5. Publish to PyPI via trusted publishing
+6. Publish the AUR package (when the `AUR_SSH_PRIVATE_KEY` secret is configured)
+7. Deploy the website to vocalinux.com
+8. Mark as pre-release if version contains alpha/beta/rc
 
 Monitor at: https://github.com/VocaHQ/vocalinux/actions
 
 ### Step 9: Post-Release Tasks
 
 - [ ] Verify GitHub Release was created correctly
-- [ ] Verify PyPI package was published (if applicable)
+- [ ] Verify `SHA256SUMS` is attached and lists all four artifacts (wheel, sdist,
+      both AppImages) — the release notes tell users to run `sha256sum -c` against it
+- [ ] Verify provenance: `gh attestation verify <artifact> --repo VocaHQ/vocalinux`
+- [ ] Verify PyPI package was published (if applicable), and that its wheel sha256
+      matches the line for that wheel in `SHA256SUMS`
 - [ ] Verify website was deployed (check vocalinux.com)
 - [ ] Announce on social media/communities
 - [ ] Update any pinned issues or discussions
diff --git a/tests/test_release_integrity.py b/tests/test_release_integrity.py
new file mode 100644
index 0000000..cc6e695
--- /dev/null
+++ b/tests/test_release_integrity.py
@@ -0,0 +1,162 @@
+"""Guard what a published release promises about itself.
+
+v0.16.1 shipped four assets — two AppImages of ~100 MB, a wheel and an sdist —
+with no checksum, no signature and no provenance, in a project that pins the
+digest of all 67 models it downloads. It also built the same version three times
+on three runners (`build-and-release`, `build-appimage-arm64`, `publish-pypi`),
+so the wheel on PyPI was never the wheel on the GitHub release, and a checksum
+for one would not have described the other.
+
+These tests pin the shape of the fix: build once, publish that, and cover every
+artifact with one manifest. Parsed as text rather than YAML on purpose — the
+sibling workflow guards do the same, and the only YAML parser on hand reaches
+the venv transitively through pre-commit.
+"""
+
+import re
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+RELEASE = REPO_ROOT / ".github" / "workflows" / "release.yml"
+
+#: The artifact holding the wheel and sdist that every other job consumes.
+DIST_ARTIFACT = "python-dist"
+
+
+def _text() -> str:
+    return RELEASE.read_text(encoding="utf-8")
+
+
+def _without_comments(text: str) -> str:
+    return "\n".join(line for line in text.splitlines() if not line.lstrip().startswith("#"))
+
+
+def _jobs() -> dict:
+    """job name -> its block of the workflow, split on the 2-space indent."""
+    text = _text()
+    start = text.index("\njobs:\n")
+    headers = list(re.finditer(r"^  ([a-z0-9][a-z0-9-]*):$", text[start:], re.M))
+    assert headers, "no jobs found; release.yml's layout moved"
+
+    jobs = {}
+    for index, header in enumerate(headers):
+        end = headers[index + 1].start() if index + 1 < len(headers) else len(text) - start
+        jobs[header.group(1)] = text[start:][header.start() : end]
+    return jobs
+
+
+def _needs(block: str) -> set:
+    match = re.search(r"^    needs: (.+)$", block, re.M)
+    if not match:
+        return set()
+    return set(re.findall(r"[a-z0-9][a-z0-9-]*", match.group(1)))
+
+
+def _permissions(block: str) -> dict:
+    match = re.search(r"^    permissions:\n((?:      \S+: \S+.*\n)+)", block, re.M)
+    if not match:
+        return {}
+    return dict(re.findall(r"^      (\S+): (\S+)", match.group(1), re.M))
+
+
+def _top_level_permissions() -> dict:
+    text = _text()
+    match = re.search(r"^permissions:\n((?:  \S+: \S+.*\n)+)", text, re.M)
+    assert match, "release.yml declares no top-level permissions"
+    return dict(re.findall(r"^  (\S+): (\S+)", match.group(1), re.M))
+
+
+def test_the_release_is_built_exactly_once():
+    """Three builds meant three sets of bytes and no `SOURCE_DATE_EPOCH`, so
+    neither a checksum nor an attestation could speak for the whole release."""
+    builds = _without_comments(_text()).count("python -m build")
+    assert builds == 1, f"the release is built {builds} times; build once and pass the artifact"
+
+
+def test_the_build_timestamp_is_pinned_to_the_tagged_commit():
+    """Otherwise re-running the tag produces bytes the published checksum no
+    longer matches."""
+    block = _jobs()["build-and-release"]
+    assert "SOURCE_DATE_EPOCH=" in block
+    assert block.index("SOURCE_DATE_EPOCH=") < block.index(
+        "python -m build\n"
+    ), "SOURCE_DATE_EPOCH is set after the build, which is the same as not setting it"
+
+
+def test_every_consumer_downloads_the_build_instead_of_repeating_it():
+    jobs = _jobs()
+    for name in ("build-appimage-arm64", "publish-pypi"):
+        block = jobs[name]
+        assert "actions/download-artifact" in block, f"{name} does not consume the build"
+        assert f"name: {DIST_ARTIFACT}" in block, f"{name} downloads some other artifact"
+        assert "python -m build" not in _without_comments(
+            block
+        ), f"{name} rebuilds what build-and-release already published"
+
+
+def _jobs_that_attach_to_the_release() -> set:
+    return {
+        name
+        for name, block in _jobs().items()
+        if "gh release upload" in block or "softprops/action-gh-release" in block
+    }
+
+
+def test_the_manifest_waits_for_every_artifact_it_has_to_cover():
+    """A SHA256SUMS listing three of the four files is worse than none: the
+    missing one is indistinguishable from a tampered one. The aarch64 AppImage
+    lands in its own job after the release exists, which is what makes this
+    ordering a real constraint rather than a formality."""
+    jobs = _jobs()
+    assert "publish-checksums" in jobs, "nothing generates a checksum manifest"
+
+    producers = _jobs_that_attach_to_the_release() - {"publish-checksums"}
+    missing = producers - _needs(jobs["publish-checksums"])
+    assert not missing, f"publish-checksums runs before {sorted(missing)} attach their artifacts"
+
+
+def test_the_manifest_covers_every_kind_of_artifact_we_publish():
+    block = _jobs()["publish-checksums"]
+    assert "merge-multiple: true" in block, "it collects one artifact, not all of them"
+    checksum_line = re.search(r"sha256sum -- (.+)$", block, re.M)
+    assert checksum_line, "publish-checksums does not generate SHA256SUMS"
+    for pattern in ("*.whl", "*.tar.gz", "*.AppImage"):
+        assert pattern in checksum_line.group(1), f"{pattern} is published but unchecksummed"
+
+
+def test_provenance_is_generated_from_the_published_manifest():
+    """Attesting a second glob would let the file users check and the set we
+    attest drift apart."""
+    block = _jobs()["publish-checksums"]
+    assert "actions/attest-build-provenance" in block, "no build provenance is generated"
+    assert (
+        "subject-checksums: dist/SHA256SUMS" in block
+    ), "provenance is not driven by the manifest we publish"
+    assert _permissions(block).get("attestations") == "write"
+
+
+def test_pypi_is_published_without_a_stored_token():
+    text = _text()
+    assert "PYPI_API_TOKEN" not in text, "trusted publishing needs no API token"
+    assert "TWINE_PASSWORD" not in text
+    block = _jobs()["publish-pypi"]
+    assert "pypa/gh-action-pypi-publish" in block
+    assert _permissions(block).get("id-token") == "write"
+
+
+def test_only_the_jobs_that_need_it_can_mint_an_oidc_token():
+    """`id-token: write` at the top level handed one to publish-aur too, which
+    runs a third-party action holding our AUR signing key."""
+    assert "id-token" not in _top_level_permissions()
+    minters = {
+        name for name, block in _jobs().items() if _permissions(block).get("id-token") == "write"
+    }
+    assert minters == {"publish-pypi", "publish-checksums"}, minters
+
+
+def test_the_release_notes_tell_users_how_to_verify_the_download():
+    """Publishing a manifest nobody is told about verifies nothing."""
+    body = _jobs()["build-and-release"]
+    assert "SHA256SUMS" in body, "the release notes never mention the manifest"
+    assert "sha256sum -c" in body, "the notes do not show how to check it"
+    assert "gh attestation verify" in body, "the notes do not show how to check provenance"
diff --git a/tests/test_workflow_action_pins.py b/tests/test_workflow_action_pins.py
new file mode 100644
index 0000000..e55db96
--- /dev/null
+++ b/tests/test_workflow_action_pins.py
@@ -0,0 +1,84 @@
+"""Pin what a third-party action actually resolves to when CI runs it.
+
+Every `uses:` in this repository floated on a moving tag — `@v4`, `@v5`,
+`@release/v1`. A tag is writable by whoever owns the action, so
+`KSXGitHub/github-actions-deploy-aur@v4.2.0`, which is handed the SSH key that
+can push to our AUR package, was whatever that tag happened to point at on the
+morning of a release. Same for the action that uploads our release assets and
+the one that publishes to PyPI.
+
+Parsed as text rather than YAML for the same reason as the sibling guards: the
+only YAML parser in the venv arrives transitively through pre-commit.
+"""
+
+import re
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+WORKFLOWS = REPO_ROOT / ".github" / "workflows"
+DEPENDABOT = REPO_ROOT / ".github" / "dependabot.yml"
+
+#: Owner whose refs may float: our own org is inside this repository's trust
+#: boundary, and a shared workflow exists to propagate without 30 version bumps.
+OWN_ORG = "vocahq"
+
+SHA = re.compile(r"^[0-9a-f]{40}$")
+
+
+def _uses() -> list:
+    """(workflow, line number, ref, trailing comment) for every `uses:`."""
+    found = []
+    for workflow in sorted(WORKFLOWS.glob("*.yml")):
+        for number, line in enumerate(workflow.read_text(encoding="utf-8").splitlines(), 1):
+            match = re.match(r"\s*uses:\s*(\S+)\s*(?:#\s*(.*))?$", line)
+            if match:
+                found.append((workflow.name, number, match.group(1), match.group(2)))
+    return found
+
+
+def test_the_workflows_are_still_where_this_test_thinks_they_are():
+    """A guard that silently scans nothing passes forever."""
+    entries = _uses()
+    assert len(entries) > 40, f"only found {len(entries)} `uses:` entries"
+
+
+def test_every_third_party_action_is_pinned_to_a_commit():
+    floating = [
+        f"{workflow}:{number} {ref}"
+        for workflow, number, ref, _ in _uses()
+        if not SHA.match(ref.rpartition("@")[2]) and not ref.lower().startswith(f"{OWN_ORG}/")
+    ]
+    assert not floating, "these run with our secrets off a moving tag:\n" + "\n".join(floating)
+
+
+def test_only_our_own_org_may_float():
+    """The exemption is a rule about trust boundaries, not a list to append to."""
+    for workflow, number, ref, _ in _uses():
+        if SHA.match(ref.rpartition("@")[2]):
+            continue
+        owner = ref.split("/")[0].lower()
+        assert owner == OWN_ORG, f"{workflow}:{number} exempts {owner}, which we do not own"
+
+
+def test_every_pin_records_the_version_it_came_from():
+    """A bare 40-hex SHA tells a reader nothing and gives Dependabot nothing to
+    bump against."""
+    unlabelled = [
+        f"{workflow}:{number} {ref}"
+        for workflow, number, ref, comment in _uses()
+        if SHA.match(ref.rpartition("@")[2]) and not comment
+    ]
+    assert not unlabelled, "pinned with no version comment:\n" + "\n".join(unlabelled)
+
+
+def test_something_moves_the_pins():
+    """A pin nobody bumps is an action that stops getting its own security
+    fixes, with the pin hiding that it has gone stale."""
+    assert DEPENDABOT.exists(), "actions are pinned but nothing updates them"
+    config = DEPENDABOT.read_text(encoding="utf-8")
+    # Anchored on the ecosystem declaration, not the bare word: "github-actions"
+    # is also the group name and appears in the comment, so a looser check passed
+    # while the ecosystem had been switched to pip.
+    assert re.search(
+        r"^\s*-\s*package-ecosystem:\s*[\"']?github-actions[\"']?\s*$", config, re.M
+    ), "dependabot.yml does not update the action pins"