diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 5051716..5dfc44a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -15,8 +15,19 @@ jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v7
-      - uses: actions/setup-node@v7
+      # Every `uses:` in this repository is pinned to a full commit SHA, with
+      # the release it belongs to in the trailing comment, and the repository
+      # requires it -- an unpinned ref fails the run rather than quietly
+      # resolving. A tag is a mutable pointer: `@v7` is whatever the publisher
+      # last moved it to, so trusting one is trusting every future version of
+      # that action, including the one pushed by whoever compromises the
+      # account. Read the comment for the version; the SHA is what runs.
+      #
+      # Dependabot updates both halves together on its weekly github-actions
+      # run, so this costs nothing to keep current -- do not "simplify" a pin
+      # back to a tag.
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 26
           cache: npm
diff --git a/.github/workflows/cleanup.yml b/.github/workflows/cleanup.yml
index fb9ddbb..95fb156 100644
--- a/.github/workflows/cleanup.yml
+++ b/.github/workflows/cleanup.yml
@@ -39,11 +39,12 @@ jobs:
     permissions:
       packages: write
     steps:
-      # Pinned to a commit rather than a moving major tag. This action is
-      # handed `packages: write` and its whole job is deletion, so a tag
-      # repointed at something else -- by a compromise or a mistake upstream --
-      # is a bad day. v1.2.2.
-      - uses: dataaxiom/ghcr-cleanup-action@d52806a0dc70b430571a37da1fde39733ffd640f
+      # The only third-party action here that is not published by GitHub or
+      # Docker, and the one with the most to lose: it is handed
+      # `packages: write` and its whole job is deletion, so a ref repointed at
+      # something else -- by a compromise or a mistake upstream -- is a bad
+      # day. It was pinned to a commit long before the rest of them were.
+      - uses: dataaxiom/ghcr-cleanup-action@d52806a0dc70b430571a37da1fde39733ffd640f # v1.2.2
         with:
           owner: Coffey-Labs
           package: ihasmail
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index a734e8d..20797c2 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -76,11 +76,11 @@ jobs:
       version: ${{ steps.v.outputs.version }}
       docker_tag: ${{ steps.v.outputs.docker_tag }}
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           ref: ${{ inputs.ref || github.ref }}
           fetch-depth: 0
-      - uses: actions/setup-node@v7
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 26
       - id: v
@@ -108,18 +108,18 @@ jobs:
           - platform: linux/arm64
             runner: ubuntu-24.04-arm
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           ref: ${{ inputs.ref || github.ref }}
-      - uses: docker/setup-buildx-action@v4
-      - uses: docker/login-action@v4
+      - uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
+      - uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Build and push by digest
         id: push
-        uses: docker/build-push-action@v7
+        uses: docker/build-push-action@c3c9e263c25d99ce0380d002d59b67737d91b0dc # v7.4.0
         with:
           context: .
           platforms: ${{ matrix.platform }}
@@ -140,7 +140,7 @@ jobs:
           # `image@sha256:sha256:...` when the reference is rebuilt.
           digest="${{ steps.push.outputs.digest }}"
           touch "/tmp/digests/${digest#sha256:}"
-      - uses: actions/upload-artifact@v7
+      - uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7.0.1
         with:
           # One artifact per platform; the merge job globs them back together.
           name: digest-${{ strategy.job-index }}
@@ -157,13 +157,13 @@ jobs:
       contents: read
       packages: write
     steps:
-      - uses: actions/download-artifact@v8
+      - uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           path: /tmp/digests
           pattern: digest-*
           merge-multiple: true
-      - uses: docker/setup-buildx-action@v4
-      - uses: docker/login-action@v4
+      - uses: docker/setup-buildx-action@594f3bf4285d9ea8dc53c9a0c9c4092420091003 # v4.4.0
+      - uses: docker/login-action@dbcb813823bdd20940b903addbd779551569679f # v4.6.0
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 89ed715..be509e9 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -54,11 +54,11 @@ jobs:
       previous: ${{ steps.decide.outputs.previous }}
       count: ${{ steps.decide.outputs.count }}
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           ref: main
           fetch-depth: 0
-      - uses: actions/setup-node@v7
+      - uses: actions/setup-node@820762786026740c76f36085b0efc47a31fe5020 # v7.0.0
         with:
           node-version: 26
       - id: decide
@@ -130,7 +130,7 @@ jobs:
     permissions:
       contents: write
     steps:
-      - uses: actions/checkout@v7
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
         with:
           ref: main
           fetch-depth: 0