diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index dad3ecd..bb17dcd 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -21,10 +21,10 @@ jobs:
       matrix:
         python: ["3.10", "3.11", "3.12", "3.13"]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v3
+        uses: astral-sh/setup-uv@caf0cab7a618c569241d31dcd442f54681755d39 # v3
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -56,10 +56,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v3
+        uses: astral-sh/setup-uv@caf0cab7a618c569241d31dcd442f54681755d39 # v3
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -77,7 +77,7 @@ jobs:
       - name: List artifacts
         run: ls -la dist/
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: dist
           path: dist/
@@ -93,7 +93,7 @@ jobs:
       # fetch-depth: 0 so gitleaks scans every commit on the branch, not just
       # the tip — secrets that were briefly committed and then removed still
       # live in history and remain harvestable.
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
         with:
           fetch-depth: 0
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index f89a706..ed8633d 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -16,10 +16,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 10
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v3
+        uses: astral-sh/setup-uv@caf0cab7a618c569241d31dcd442f54681755d39 # v3
         with:
           enable-cache: true
           cache-dependency-glob: "pyproject.toml"
@@ -77,7 +77,7 @@ jobs:
       - name: Validate distribution metadata
         run: uv tool run twine check dist/*
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
         with:
           name: dist
           path: dist/
@@ -97,7 +97,7 @@ jobs:
     permissions:
       id-token: write  # OIDC for trusted publishing
     steps:
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
         with:
           name: dist
           path: dist/
@@ -119,7 +119,7 @@ jobs:
     permissions:
       id-token: write
     steps:
-      - uses: actions/download-artifact@v4
+      - uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4
         with:
           name: dist
           path: dist/
diff --git a/.github/workflows/sync-upstream.yml b/.github/workflows/sync-upstream.yml
index 51ea754..3d09624 100644
--- a/.github/workflows/sync-upstream.yml
+++ b/.github/workflows/sync-upstream.yml
@@ -19,10 +19,10 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 15
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Install uv
-        uses: astral-sh/setup-uv@v3
+        uses: astral-sh/setup-uv@caf0cab7a618c569241d31dcd442f54681755d39 # v3
 
       - name: Set up Python 3.13
         run: uv python install 3.13