diff --git a/.github/workflows/benchmarks.yaml b/.github/workflows/benchmarks.yaml
index c80a582..de5fd45 100644
--- a/.github/workflows/benchmarks.yaml
+++ b/.github/workflows/benchmarks.yaml
@@ -37,12 +37,12 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             10.0.x
diff --git a/.github/workflows/build-all-versions.yaml b/.github/workflows/build-all-versions.yaml
index 9e77141..150c67f 100644
--- a/.github/workflows/build-all-versions.yaml
+++ b/.github/workflows/build-all-versions.yaml
@@ -25,13 +25,13 @@ jobs:
 
     steps:
       - name: Checkout repository (full history + all tags)
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           fetch-depth: 0 # Full history so all tags are reachable
           persist-credentials: false
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             5.0.x
diff --git a/.github/workflows/codeql.yaml b/.github/workflows/codeql.yaml
index 0b2b6f9..29a43fc 100644
--- a/.github/workflows/codeql.yaml
+++ b/.github/workflows/codeql.yaml
@@ -31,7 +31,7 @@ jobs:
 
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v7
+      uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
       with:
         persist-credentials: false
 
@@ -77,7 +77,7 @@ jobs:
 
     - name: Initialize CodeQL
       if: steps.check-csharp.outputs.has-csharp == 'true'
-      uses: github/codeql-action/init@v4
+      uses: github/codeql-action/init@e0647621c2984b5ed2f768cb892365bf2a616ad1 # v4
       with:
         languages: ${{ matrix.language }}
         # security-extended adds the broader security query pack on top of the
@@ -86,7 +86,7 @@ jobs:
 
     - name: Setup .NET
       if: steps.check-csharp.outputs.has-csharp == 'true'
-      uses: actions/setup-dotnet@v6
+      uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
       with:
         dotnet-version: '10.0.x'
 
@@ -159,7 +159,7 @@ jobs:
     - name: Perform CodeQL Analysis
       id: perform-codeql-analysis
       if: steps.check-csharp.outputs.has-csharp == 'true'
-      uses: github/codeql-action/analyze@v4
+      uses: github/codeql-action/analyze@e0647621c2984b5ed2f768cb892365bf2a616ad1 # v4
       with:
         category: "/language:${{matrix.language}}"
 
diff --git a/.github/workflows/docfx.yaml b/.github/workflows/docfx.yaml
index 4f08c31..c0279e9 100644
--- a/.github/workflows/docfx.yaml
+++ b/.github/workflows/docfx.yaml
@@ -60,7 +60,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           fetch-depth: 0  # Full history needed to enumerate all v* tags
           persist-credentials: false
@@ -127,7 +127,7 @@ jobs:
           }
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             5.0.x
diff --git a/.github/workflows/pr.yaml b/.github/workflows/pr.yaml
index f062a57..4e59bf4 100644
--- a/.github/workflows/pr.yaml
+++ b/.github/workflows/pr.yaml
@@ -42,7 +42,7 @@ jobs:
     if: github.repository != 'Chris-Wolfgang/repo-template'
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -96,7 +96,7 @@ jobs:
     
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -251,7 +251,7 @@ jobs:
     
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -338,7 +338,7 @@ jobs:
           sudo rm /etc/apt/sources.list.d/focal-security.list
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -626,7 +626,7 @@ jobs:
 
       - name: Upload Linux coverage results
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: coverage-linux
           path: |
@@ -634,7 +634,7 @@ jobs:
             CoverageReport/
 
       - name: Upload build artifacts
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: build-output
           path: |
@@ -652,7 +652,7 @@ jobs:
     
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -720,7 +720,7 @@ jobs:
           Write-Host "✅ Configuration files secured - using versions from main branch"
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -958,7 +958,7 @@ jobs:
 
       - name: Upload Windows coverage results
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: coverage-windows
           path: |
@@ -976,7 +976,7 @@ jobs:
     
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -1048,7 +1048,7 @@ jobs:
           echo "✅ Configuration files secured - using versions from main branch"
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             6.0.x
@@ -1313,7 +1313,7 @@ jobs:
 
       - name: Upload macOS coverage results
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: coverage-macos
           path: |
@@ -1363,7 +1363,7 @@ jobs:
     
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           ref: refs/pull/${{ github.event.pull_request.number }}/head
           persist-credentials: false
@@ -1468,7 +1468,7 @@ jobs:
 
       - name: Upload security scan results
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: devskim-results
           path: devskim-results.txt
diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index d6c43d4..ad50826 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -26,7 +26,7 @@ jobs:
     if: github.repository != 'Chris-Wolfgang/repo-template'
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
@@ -85,7 +85,7 @@ jobs:
           }
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -340,7 +340,7 @@ jobs:
 
       - name: Upload coverage report
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: release-coverage
           path: CoverageReport/
@@ -354,12 +354,12 @@ jobs:
       has-packages: ${{ steps.check-packages.outputs.has-packages }}
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -562,7 +562,7 @@ jobs:
 
 
       - name: Upload NuGet packages
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: nuget-packages
           path: ./nuget-packages/
@@ -581,7 +581,7 @@ jobs:
     if: github.repository != 'Chris-Wolfgang/repo-template'
     steps:
       - name: Checkout code
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
@@ -598,7 +598,7 @@ jobs:
 
       - name: Setup .NET
         if: steps.check.outputs.found == 'true'
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           # Install the same SDK set as validate-release so dotnet build can
           # compile every TFM the solution targets (some test projects span
@@ -674,7 +674,7 @@ jobs:
     runs-on: windows-latest
     steps:
       - name: Setup .NET
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -686,7 +686,7 @@ jobs:
             10.0.x
 
       - name: Download packages
-        uses: actions/download-artifact@v8.0.1
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: nuget-packages
           path: ./packages
@@ -758,13 +758,13 @@ jobs:
       contents: write  # Required to upload assets to the GitHub Release
     steps:
       - name: Download NuGet packages artifact
-        uses: actions/download-artifact@v8.0.1
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: nuget-packages
           path: ./nuget-packages
 
       - name: Download coverage report artifact
-        uses: actions/download-artifact@v8.0.1
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8.0.1
         with:
           name: release-coverage
           path: ./release-coverage
diff --git a/.github/workflows/sourcelink-stepinto.yaml b/.github/workflows/sourcelink-stepinto.yaml
index 593867d..8b9ecff 100644
--- a/.github/workflows/sourcelink-stepinto.yaml
+++ b/.github/workflows/sourcelink-stepinto.yaml
@@ -47,7 +47,7 @@ jobs:
     timeout-minutes: 20
     steps:
       - name: Checkout code
-        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
@@ -63,7 +63,7 @@ jobs:
 
       - name: Setup .NET
         if: steps.detect.outputs.found == 'true'
-        uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: '10.0.x'
 
diff --git a/.github/workflows/sourcelink.yaml b/.github/workflows/sourcelink.yaml
index 1ffd5df..abbc94b 100644
--- a/.github/workflows/sourcelink.yaml
+++ b/.github/workflows/sourcelink.yaml
@@ -40,7 +40,7 @@ jobs:
     timeout-minutes: 10
     steps:
       - name: Checkout code
-        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
@@ -56,7 +56,7 @@ jobs:
 
       - name: Setup .NET
         if: steps.detect.outputs.found == 'true'
-        uses: actions/setup-dotnet@26b0ec14cb23fa6904739307f278c14f94c95bf1 # v5
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: '10.0.x'
 
diff --git a/.github/workflows/stryker.yaml b/.github/workflows/stryker.yaml
index 576059c..5eafc46 100644
--- a/.github/workflows/stryker.yaml
+++ b/.github/workflows/stryker.yaml
@@ -43,7 +43,7 @@ jobs:
     timeout-minutes: 120
     steps:
       - name: Check out repo
-        uses: actions/checkout@v7
+        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7
         with:
           persist-credentials: false
 
@@ -52,7 +52,7 @@ jobs:
         # through .NET 10.0). Stryker has to be able to build whichever
         # TFM each test project targets; pinning to a subset would
         # silently fail repos that target older runtimes.
-        uses: actions/setup-dotnet@v6
+        uses: actions/setup-dotnet@a98b56852c35b8e3190ac28c8c2271da59106c68 # v6
         with:
           dotnet-version: |
             3.1.x
@@ -123,7 +123,7 @@ jobs:
 
       - name: Upload Stryker report
         if: always()
-        uses: actions/upload-artifact@v7
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
         with:
           name: stryker-report-${{ github.run_id }}
           path: |
diff --git a/.zizmor.yml b/.zizmor.yml
new file mode 100644
index 0000000..f9d2374
--- /dev/null
+++ b/.zizmor.yml
@@ -0,0 +1,14 @@
+# zizmor configuration (#143 follow-up).
+#
+# NOTE: zizmor does NOT auto-discover this file — it must be passed explicitly
+# with `--config .zizmor.yml` on every invocation (see actions-audit.yaml).
+#
+# Every action in .github/workflows/** is pinned to a full commit SHA with a
+# `# vX` version comment (fleet SHA-pin convention). Enforce that: require a
+# hash pin for all actions, so a future tag-pin (`@v7`) or unpinned ref is
+# flagged by the `unpinned-uses` rule.
+rules:
+  unpinned-uses:
+    config:
+      policies:
+        "*": hash-pin