diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c9d3b2f..b5dec78 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,6 +7,15 @@ on:
     branches: [ main ]
 
 jobs:
+  workflow-lint:
+    name: Lint GitHub Actions workflows
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v6
+      - name: actionlint
+        uses: rhysd/actionlint@v1.7.12
+
   changes:
     name: Detect package-impacting changes
     runs-on: ubuntu-latest
@@ -21,7 +30,7 @@ jobs:
       any_changed: ${{ steps.flags.outputs.any_changed }}
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 
@@ -33,6 +42,12 @@ jobs:
             workflows:
               - '.github/workflows/ci.yml'
               - '.github/workflows/release.yml'
+            tooling:
+              - 'Directory.Build.props'
+              - 'Directory.Packages.props'
+              - 'src/analyticsLibrary.ReleaseTooling/**'
+              - 'tools/analyticsLibrary.NuGetMaintenance/**'
+              - 'tests/analyticsLibrary.ReleaseTooling.Tests/**'
             core:
               - 'src/analyticsLibrary.Core/**'
             algorithms:
@@ -51,6 +66,13 @@ jobs:
       - name: Compute effective package flags
         id: flags
         run: |
+          if [ '${{ steps.filter.outputs.tooling }}' = "true" ]; then
+            for n in core_changed algorithms_changed statistics_changed excel_changed access_changed hadoop_changed root_changed any_changed; do
+              echo "${n}=true" >> "$GITHUB_OUTPUT"
+            done
+            exit 0
+          fi
+
           WORKFLOWS_CHANGED='${{ steps.filter.outputs.workflows }}'
           set_flag() {
             local name="$1"
@@ -86,7 +108,9 @@ jobs:
   no-package-changes:
     name: No package-impacting changes
     runs-on: ubuntu-latest
-    needs: changes
+    needs:
+      - changes
+      - workflow-lint
     if: needs.changes.outputs.any_changed != 'true'
     steps:
       - name: Skip message
@@ -95,15 +119,17 @@ jobs:
   build-test-pack:
     name: Build, Test, and Pack
     runs-on: ubuntu-latest
-    needs: changes
+    needs:
+      - changes
+      - workflow-lint
     if: needs.changes.outputs.any_changed == 'true'
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v5
         with:
           dotnet-version: '8.0.x'
 
@@ -114,7 +140,7 @@ jobs:
         run: dotnet build -c Release --no-restore
 
       - name: Test
-        run: dotnet test -c Release --no-build --verbosity normal
+        run: dotnet test -c Release --no-build --verbosity normal --filter "Category!=Integration"
 
       - name: Pack
         run: |
@@ -180,7 +206,7 @@ jobs:
             local package_name="$2"
             if [ "$should_pack" = "true" ]; then
               EXPECTED=$((EXPECTED+1))
-              if ! ls ./artifacts/${package_name}.*.nupkg 1>/dev/null 2>&1; then
+              if ! ls "./artifacts/${package_name}."*.nupkg 1>/dev/null 2>&1; then
                 echo "ERROR: Expected package not found: ${package_name}"
                 exit 1
               fi
@@ -202,7 +228,7 @@ jobs:
           echo "All expected packages found."
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: nuget-packages-${{ github.run_id }}
           path: ./artifacts/*.nupkg
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index d923308..6d71b00 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -12,125 +12,17 @@ on:
         default: '2.0.0'
 
 jobs:
-  changes:
-    name: Detect package-impacting changes
-    runs-on: ubuntu-latest
-    outputs:
-      core_changed: ${{ steps.flags.outputs.core_changed }}
-      algorithms_changed: ${{ steps.flags.outputs.algorithms_changed }}
-      statistics_changed: ${{ steps.flags.outputs.statistics_changed }}
-      excel_changed: ${{ steps.flags.outputs.excel_changed }}
-      access_changed: ${{ steps.flags.outputs.access_changed }}
-      hadoop_changed: ${{ steps.flags.outputs.hadoop_changed }}
-      root_changed: ${{ steps.flags.outputs.root_changed }}
-      any_changed: ${{ steps.flags.outputs.any_changed }}
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v4
-        with:
-          fetch-depth: 0
-
-      - name: Resolve comparison base
-        id: base
-        run: |
-          if [ "${{ github.event_name }}" = "push" ]; then
-            BASE="${{ github.event.before }}"
-            if [ -n "$BASE" ] && [ "$BASE" != "0000000000000000000000000000000000000000" ]; then
-              echo "base_ref=$BASE" >> "$GITHUB_OUTPUT"
-              exit 0
-            fi
-          fi
-
-          PREV_TAG="$(git tag --sort=-creatordate | sed -n '2p')"
-          if [ -z "$PREV_TAG" ]; then
-            BASE="$(git rev-list --max-parents=0 HEAD | sed -n '1p')"
-          else
-            BASE="$(git rev-list -n 1 "$PREV_TAG")"
-          fi
-          echo "base_ref=$BASE" >> "$GITHUB_OUTPUT"
-
-      - name: Detect changed paths
-        id: filter
-        uses: dorny/paths-filter@v3
-        with:
-          base: ${{ steps.base.outputs.base_ref }}
-          ref: ${{ github.sha }}
-          filters: |
-            workflows:
-              - '.github/workflows/ci.yml'
-              - '.github/workflows/release.yml'
-            core:
-              - 'src/analyticsLibrary.Core/**'
-            algorithms:
-              - 'src/analyticsLibrary.Algorithms/**'
-            statistics:
-              - 'src/analyticsLibrary.Statistics/**'
-            excel:
-              - 'src/analyticsLibrary.Excel/**'
-            access:
-              - 'src/analyticsLibrary.Access/**'
-            hadoop:
-              - 'src/analyticsLibrary.Hadoop/**'
-            root:
-              - 'src/analyticsLibrary/**'
-
-      - name: Compute effective package flags
-        id: flags
-        run: |
-          WORKFLOWS_CHANGED='${{ steps.filter.outputs.workflows }}'
-          set_flag() {
-            local name="$1"
-            local raw="$2"
-            if [ "$raw" = "true" ] || [ "$WORKFLOWS_CHANGED" = "true" ]; then
-              echo "${name}=true" >> "$GITHUB_OUTPUT"
-            else
-              echo "${name}=false" >> "$GITHUB_OUTPUT"
-            fi
-          }
-
-          set_flag core_changed '${{ steps.filter.outputs.core }}'
-          set_flag algorithms_changed '${{ steps.filter.outputs.algorithms }}'
-          set_flag statistics_changed '${{ steps.filter.outputs.statistics }}'
-          set_flag excel_changed '${{ steps.filter.outputs.excel }}'
-          set_flag access_changed '${{ steps.filter.outputs.access }}'
-          set_flag hadoop_changed '${{ steps.filter.outputs.hadoop }}'
-          set_flag root_changed '${{ steps.filter.outputs.root }}'
-
-          if [ '${{ steps.filter.outputs.core }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.algorithms }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.statistics }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.excel }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.access }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.hadoop }}' = "true" ] || \
-             [ '${{ steps.filter.outputs.root }}' = "true" ] || \
-             [ "$WORKFLOWS_CHANGED" = "true" ]; then
-            echo "any_changed=true" >> "$GITHUB_OUTPUT"
-          else
-            echo "any_changed=false" >> "$GITHUB_OUTPUT"
-          fi
-
-  no-package-changes:
-    name: No package-impacting changes
-    runs-on: ubuntu-latest
-    needs: changes
-    if: needs.changes.outputs.any_changed != 'true'
-    steps:
-      - name: Skip message
-        run: echo "No package-impacting changes detected since the release baseline; skipping NuGet release."
-
   release:
-    name: Build, Test, Pack, and Deploy
+    name: Build, Test, Pack, Deploy, and Deprecate
     runs-on: ubuntu-latest
     environment: nuget-release
-    needs: changes
-    if: needs.changes.outputs.any_changed == 'true'
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup .NET
-        uses: actions/setup-dotnet@v4
+        uses: actions/setup-dotnet@v5
         with:
           dotnet-version: '8.0.x'
 
@@ -140,10 +32,9 @@ jobs:
           if [ "${{ github.event_name }}" = "workflow_dispatch" ]; then
             VERSION="${{ github.event.inputs.version }}"
           else
-            # Strip the leading 'v' from tag name (e.g. v2.0.0 -> 2.0.0)
             VERSION="${GITHUB_REF_NAME#v}"
           fi
-          echo "VERSION=$VERSION" >> $GITHUB_OUTPUT
+          echo "VERSION=$VERSION" >> "$GITHUB_OUTPUT"
           echo "Release version: $VERSION"
 
       - name: Restore
@@ -153,85 +44,70 @@ jobs:
         run: dotnet build -c Release --no-restore
 
       - name: Test
-        run: dotnet test -c Release --no-build --verbosity normal
+        run: dotnet test -c Release --no-build --verbosity normal --filter "Category!=Integration"
 
-      - name: Pack
+      - name: Validate release version against project versions
         run: |
-          mkdir -p ./artifacts
-          PACKED=0
-
-          if [ "${{ needs.changes.outputs.core_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Core/analyticsLibrary.Core.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.algorithms_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Algorithms/analyticsLibrary.Algorithms.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.statistics_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Statistics/analyticsLibrary.Statistics.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.excel_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Excel/analyticsLibrary.Excel.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.access_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Access/analyticsLibrary.Access.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.hadoop_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary.Hadoop/analyticsLibrary.Hadoop.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-          if [ "${{ needs.changes.outputs.root_changed }}" = "true" ]; then
-            dotnet pack src/analyticsLibrary/analyticsLibrary.csproj -c Release --no-build -o ./artifacts
-            PACKED=$((PACKED+1))
-          fi
-
-          if [ "$PACKED" -eq 0 ]; then
-            echo "No package projects selected for packing."
+          V="${{ steps.version.outputs.VERSION }}"
+          if ! [[ "$V" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+            echo "ERROR: Release version must be SemVer major.minor.patch (got '$V')."
             exit 1
           fi
 
+          PROJECTS=(
+            src/analyticsLibrary.Core/analyticsLibrary.Core.csproj
+            src/analyticsLibrary.Algorithms/analyticsLibrary.Algorithms.csproj
+            src/analyticsLibrary.Statistics/analyticsLibrary.Statistics.csproj
+            src/analyticsLibrary.Excel/analyticsLibrary.Excel.csproj
+            src/analyticsLibrary.Access/analyticsLibrary.Access.csproj
+            src/analyticsLibrary.Hadoop/analyticsLibrary.Hadoop.csproj
+            src/analyticsLibrary/analyticsLibrary.csproj
+          )
+
+          for csproj in "${PROJECTS[@]}"; do
+            current=$(grep -oPm1 '<Version>\K[^<]+' "$csproj")
+            if [ -z "$current" ]; then
+              echo "ERROR: Could not read <Version> from $csproj"
+              exit 1
+            fi
+
+            max_version=$(printf '%s\n%s\n' "$V" "$current" | sort -V | tail -n1)
+            if [ "$max_version" != "$V" ]; then
+              echo "ERROR: Requested release version $V is lower than project version $current in $csproj"
+              exit 1
+            fi
+          done
+
+      - name: Pack all packages
+        run: |
+          mkdir -p ./artifacts
+          V="${{ steps.version.outputs.VERSION }}"
+          dotnet pack src/analyticsLibrary.Core/analyticsLibrary.Core.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary.Algorithms/analyticsLibrary.Algorithms.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary.Statistics/analyticsLibrary.Statistics.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary.Excel/analyticsLibrary.Excel.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary.Access/analyticsLibrary.Access.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary.Hadoop/analyticsLibrary.Hadoop.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+          dotnet pack src/analyticsLibrary/analyticsLibrary.csproj -c Release --no-build "-p:Version=$V" -o ./artifacts
+
       - name: Inspect packages
         run: |
           echo "Produced packages:"
           ls -la ./artifacts/*.nupkg
-          EXPECTED=0
-          MISSING=0
-          verify_pkg() {
-            local should_pack="$1"
-            local package_name="$2"
-            if [ "$should_pack" = "true" ]; then
-              EXPECTED=$((EXPECTED+1))
-              if ! ls ./artifacts/${package_name}.*.nupkg 1>/dev/null 2>&1; then
-                echo "ERROR: Expected package not found: ${package_name}"
-                MISSING=$((MISSING+1))
-              fi
+          for id in analyticsLibrary.Core analyticsLibrary.Algorithms analyticsLibrary.Statistics analyticsLibrary.Excel analyticsLibrary.Access analyticsLibrary.Hadoop; do
+            if ! ls "./artifacts/${id}."*.nupkg 1>/dev/null 2>&1; then
+              echo "ERROR: Expected package not found: ${id}"
+              exit 1
             fi
-          }
-
-          verify_pkg "${{ needs.changes.outputs.core_changed }}" "analyticsLibrary.Core"
-          verify_pkg "${{ needs.changes.outputs.algorithms_changed }}" "analyticsLibrary.Algorithms"
-          verify_pkg "${{ needs.changes.outputs.statistics_changed }}" "analyticsLibrary.Statistics"
-          verify_pkg "${{ needs.changes.outputs.excel_changed }}" "analyticsLibrary.Excel"
-          verify_pkg "${{ needs.changes.outputs.access_changed }}" "analyticsLibrary.Access"
-          verify_pkg "${{ needs.changes.outputs.hadoop_changed }}" "analyticsLibrary.Hadoop"
-          verify_pkg "${{ needs.changes.outputs.root_changed }}" "analyticsLibrary"
-
-          if [ "$EXPECTED" -eq 0 ]; then
-            echo "Aborting: No packages were expected after change detection."
+          done
+          if ! ls ./artifacts/analyticsLibrary.[0-9]*.nupkg 1>/dev/null 2>&1; then
+            echo "ERROR: Expected root package not found: analyticsLibrary.<semver>.nupkg"
             exit 1
           fi
-          if [ "$MISSING" -gt 0 ]; then
-            echo "Aborting: $MISSING expected package(s) are missing."
-            exit 1
-          fi
-          echo "All expected packages found and ready for deployment."
+          echo "All ${{ steps.version.outputs.VERSION }} packages found and ready for deployment."
 
       - name: Upload release artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: nuget-packages-${{ steps.version.outputs.VERSION }}
           path: ./artifacts/*.nupkg
@@ -240,6 +116,16 @@ jobs:
       - name: Deploy to NuGet
         run: |
           dotnet nuget push ./artifacts/*.nupkg \
-            --api-key ${{ secrets.NUGET_API_KEY }} \
+            --api-key "${{ secrets.NUGET_API_KEY }}" \
             --source https://api.nuget.org/v3/index.json \
             --skip-duplicate
+
+      - name: Deprecate prior versions on NuGet.org
+        env:
+          NUGET_API_KEY: ${{ secrets.NUGET_API_KEY }}
+        run: |
+          if [ -z "$NUGET_API_KEY" ]; then
+            echo "NUGET_API_KEY is not set; skipping deprecation."
+            exit 0
+          fi
+          dotnet run -c Release --no-build --project tools/analyticsLibrary.NuGetMaintenance -- apply-deprecations "${{ steps.version.outputs.VERSION }}"
diff --git a/Analytics Library.sln b/Analytics Library.sln
index 75a7170..0741ad0 100755
--- a/Analytics Library.sln	
+++ b/Analytics Library.sln	
@@ -29,6 +29,14 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "analyticsLibrary.Algorithms
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "analyticsLibrary.Excel.Tests", "tests\analyticsLibrary.Excel.Tests\analyticsLibrary.Excel.Tests.csproj", "{660F8C89-9149-452D-9E97-222E18D769D3}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "analyticsLibrary.ReleaseTooling", "src\analyticsLibrary.ReleaseTooling\analyticsLibrary.ReleaseTooling.csproj", "{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tools", "tools", "{07C2787E-EAC7-C090-1BA3-A61EC2A24D84}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "analyticsLibrary.NuGetMaintenance", "tools\analyticsLibrary.NuGetMaintenance\analyticsLibrary.NuGetMaintenance.csproj", "{1AAC51AF-5725-4377-8B33-0C094DE34B17}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "analyticsLibrary.ReleaseTooling.Tests", "tests\analyticsLibrary.ReleaseTooling.Tests\analyticsLibrary.ReleaseTooling.Tests.csproj", "{9BB1015E-6FA9-4734-9527-23ACB23898C2}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		CD_ROM|Any CPU = CD_ROM|Any CPU
@@ -516,6 +524,132 @@ Global
 		{660F8C89-9149-452D-9E97-222E18D769D3}.SingleImage|x64.Build.0 = Debug|Any CPU
 		{660F8C89-9149-452D-9E97-222E18D769D3}.SingleImage|x86.ActiveCfg = Debug|Any CPU
 		{660F8C89-9149-452D-9E97-222E18D769D3}.SingleImage|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.CD_ROM|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug x86|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Debug|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.DVD-5|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release x86|x86.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|Any CPU.Build.0 = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|x64.ActiveCfg = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|x64.Build.0 = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|x86.ActiveCfg = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.Release|x86.Build.0 = Release|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|Any CPU.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|Any CPU.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|x64.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|x64.Build.0 = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|x86.ActiveCfg = Debug|Any CPU
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90}.SingleImage|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.CD_ROM|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug x86|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Debug|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.DVD-5|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release x86|x86.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|Any CPU.Build.0 = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|x64.ActiveCfg = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|x64.Build.0 = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|x86.ActiveCfg = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.Release|x86.Build.0 = Release|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|Any CPU.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|Any CPU.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|x64.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|x64.Build.0 = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|x86.ActiveCfg = Debug|Any CPU
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17}.SingleImage|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.CD_ROM|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug x86|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Debug|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.DVD-5|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release x86|x86.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|Any CPU.Build.0 = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|x64.ActiveCfg = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|x64.Build.0 = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|x86.ActiveCfg = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.Release|x86.Build.0 = Release|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|Any CPU.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|Any CPU.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|x64.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|x64.Build.0 = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|x86.ActiveCfg = Debug|Any CPU
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2}.SingleImage|x86.Build.0 = Debug|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -532,6 +666,9 @@ Global
 		{23A3F035-185E-485F-80D8-DCBBDBD6CFA9} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
 		{1C80F5C6-8A99-4941-8A81-97A28C60C3E8} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
 		{660F8C89-9149-452D-9E97-222E18D769D3} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
+		{D5B7B9CE-2BF9-44D1-991F-8D175B183A90} = {827E0CD3-B72D-47B6-A68D-7590B98EB39B}
+		{1AAC51AF-5725-4377-8B33-0C094DE34B17} = {07C2787E-EAC7-C090-1BA3-A61EC2A24D84}
+		{9BB1015E-6FA9-4734-9527-23ACB23898C2} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {52B0CB57-8044-4EA5-BC6B-F17324054845}
diff --git a/Directory.Packages.props b/Directory.Packages.props
index 32f3799..3caa684 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -27,5 +27,6 @@
     <PackageVersion Include="xunit" Version="2.9.3" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.8.2" />
     <PackageVersion Include="coverlet.collector" Version="6.0.4" />
+    <PackageVersion Include="NuGet.Versioning" Version="6.12.1" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/README.md b/README.md
index f4a9e7a..1ad77c8 100644
--- a/README.md
+++ b/README.md
@@ -249,18 +249,24 @@ dotnet pack -c Release -o ./nupkgs
 
 **Beta packages (pull requests)**
 
-Opening or updating a pull request against `main` triggers `ci.yml`. The workflow builds, tests, packs beta packages versioned `2.0.0-beta.pr-<pr>.<run>`, and uploads them as workflow artifacts. Beta packages are only pushed to NuGet.org when the `NUGET_API_KEY` secret is available and the PR is not from a fork.
+Opening or updating a pull request against `main` triggers `ci.yml`. The workflow builds, tests, packs only the package projects whose `src/analyticsLibrary.*` paths changed (or when central/tooling paths change—see workflow filters), using beta versions read from each `.csproj` `<Version>` plus `-beta.pr-<pr>.<run>`. It uploads `.nupkg` files as workflow artifacts. Beta packages are pushed to NuGet.org only on the `pull_request` event when `NUGET_API_KEY` is set and the PR branch is from the same repository (not a fork). Merging the PR to `main` does **not** publish betas to NuGet.org.
 
-**Release packages**
+**Stable release packages**
 
-Push a version tag (e.g. `v2.0.0`) or trigger `release.yml` manually via workflow dispatch. The workflow:
-1. Builds and tests the solution from the tagged commit.
-2. Packs all seven packages.
-3. Verifies all expected `.nupkg` files are present.
-4. Deploys to NuGet.org under the `nuget-release` GitHub Environment, which requires explicit approval before the deploy step runs.
+Publishing a stable release to NuGet.org is **not** triggered by merging a pull request alone. You must either push a SemVer tag matching `v*.*.*` (for example `v3.0.0`) at the commit you want to ship, or run `release.yml` manually via **workflow dispatch** and enter the version (for example `3.0.0`).
+
+The `release.yml` workflow then:
+
+1. Builds and tests the full solution (including release-tooling tests under `tests/analyticsLibrary.ReleaseTooling.Tests/`).
+2. Packs **all seven** packages at the same release version (no path-based skipping).
+3. Verifies every expected `.nupkg` is present.
+4. Pushes packages to NuGet.org. This step uses the `nuget-release` GitHub Environment so you can require manual approval before anything is published.
+5. Deprecates previously published versions on NuGet.org: all CI beta builds whose versions contain `-beta.pr-` are marked with an “other” deprecation reason and a testing-only message; every older **stable** version below the version you just shipped is marked **legacy** with the message: `This package is legacy and is no longer maintained`. The deprecation client calls NuGet.org’s HTTP API (`PUT https://www.nuget.org/api/v2/package/{packageId}/deprecations`) using the same `NUGET_API_KEY`. The key must include permission to **push** and **unlist** (deprecation uses the unlist scope on nuget.org). If NuGet.org returns **403** for deprecation, the account may not yet have the manage-deprecation API enabled for API keys; in that case you can deprecate versions manually on nuget.org until the API is available.
 
 Store the NuGet API key as a repository secret named `NUGET_API_KEY`. Never commit credentials.
 
+CI also runs [actionlint](https://github.com/rhysd/actionlint) on workflow files.
+
 ---
 
 ## Contributing
diff --git a/src/analyticsLibrary.ReleaseTooling/FlatContainerIndexParser.cs b/src/analyticsLibrary.ReleaseTooling/FlatContainerIndexParser.cs
new file mode 100644
index 0000000..5efa69c
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/FlatContainerIndexParser.cs
@@ -0,0 +1,30 @@
+using System.Text.Json;
+
+namespace analyticsLibrary.ReleaseTooling;
+
+public static class FlatContainerIndexParser
+{
+    public static IReadOnlyList<string> ParseVersions(string json)
+    {
+        using var doc = JsonDocument.Parse(json);
+        if (!doc.RootElement.TryGetProperty("versions", out var versions) || versions.ValueKind != JsonValueKind.Array)
+        {
+            return Array.Empty<string>();
+        }
+
+        var list = new List<string>();
+        foreach (var el in versions.EnumerateArray())
+        {
+            if (el.ValueKind == JsonValueKind.String)
+            {
+                var s = el.GetString();
+                if (!string.IsNullOrEmpty(s))
+                {
+                    list.Add(s);
+                }
+            }
+        }
+
+        return list;
+    }
+}
diff --git a/src/analyticsLibrary.ReleaseTooling/NuGetFlatContainerHttp.cs b/src/analyticsLibrary.ReleaseTooling/NuGetFlatContainerHttp.cs
new file mode 100644
index 0000000..c9759fc
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/NuGetFlatContainerHttp.cs
@@ -0,0 +1,24 @@
+namespace analyticsLibrary.ReleaseTooling;
+
+public static class NuGetFlatContainerHttp
+{
+    public static Uri GetPackageIndexUri(string packageId) =>
+        new($"https://api.nuget.org/v3-flatcontainer/{packageId.ToLowerInvariant()}/index.json", UriKind.Absolute);
+
+    public static async Task<IReadOnlyList<string>> GetPublishedVersionsAsync(
+        HttpClient http,
+        string packageId,
+        CancellationToken cancellationToken = default)
+    {
+        var uri = GetPackageIndexUri(packageId);
+        using var response = await http.GetAsync(uri, cancellationToken).ConfigureAwait(false);
+        if (response.StatusCode == System.Net.HttpStatusCode.NotFound)
+        {
+            return Array.Empty<string>();
+        }
+
+        response.EnsureSuccessStatusCode();
+        var json = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+        return FlatContainerIndexParser.ParseVersions(json);
+    }
+}
diff --git a/src/analyticsLibrary.ReleaseTooling/NuGetGalleryDeprecationApi.cs b/src/analyticsLibrary.ReleaseTooling/NuGetGalleryDeprecationApi.cs
new file mode 100644
index 0000000..2d26ae0
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/NuGetGalleryDeprecationApi.cs
@@ -0,0 +1,62 @@
+namespace analyticsLibrary.ReleaseTooling;
+
+public static class NuGetGalleryDeprecationApi
+{
+    public const string DeprecationEndpointTemplate = "https://www.nuget.org/api/v2/package/{0}/deprecations";
+
+    public static HttpRequestMessage CreateDeprecationRequest(
+        string packageId,
+        IReadOnlyList<string> versions,
+        bool isLegacy,
+        bool hasCriticalBugs,
+        bool isOther,
+        string? customMessage,
+        string alternatePackageId,
+        string alternatePackageVersion,
+        string apiKey)
+    {
+        if (versions.Count == 0)
+        {
+            throw new ArgumentException("At least one version is required.", nameof(versions));
+        }
+
+        var pairs = new List<KeyValuePair<string, string>>();
+        for (var i = 0; i < versions.Count; i++)
+        {
+            pairs.Add(new KeyValuePair<string, string>($"versions[{i}]", versions[i]));
+        }
+
+        if (isLegacy)
+        {
+            pairs.Add(new KeyValuePair<string, string>("isLegacy", "true"));
+        }
+
+        if (hasCriticalBugs)
+        {
+            pairs.Add(new KeyValuePair<string, string>("hasCriticalBugs", "true"));
+        }
+
+        if (isOther)
+        {
+            pairs.Add(new KeyValuePair<string, string>("isOther", "true"));
+        }
+
+        if (!string.IsNullOrEmpty(customMessage))
+        {
+            pairs.Add(new KeyValuePair<string, string>("message", customMessage));
+        }
+
+        pairs.Add(new KeyValuePair<string, string>("alternatePackageId", alternatePackageId));
+        pairs.Add(new KeyValuePair<string, string>("alternatePackageVersion", alternatePackageVersion));
+        pairs.Add(new KeyValuePair<string, string>("listedVerb", "Unchanged"));
+
+        var url = string.Format(DeprecationEndpointTemplate, Uri.EscapeDataString(packageId));
+        var request = new HttpRequestMessage(HttpMethod.Put, url);
+        request.Headers.TryAddWithoutValidation("X-NuGet-ApiKey", apiKey);
+        request.Headers.TryAddWithoutValidation(
+            "User-Agent",
+            "analyticsLibrary-release-workflow/1.0 (+https://github.com/hpractv/analyticsLibrary)");
+        request.Content = new FormUrlEncodedContent(pairs);
+        return request;
+    }
+}
diff --git a/src/analyticsLibrary.ReleaseTooling/ReleaseConstants.cs b/src/analyticsLibrary.ReleaseTooling/ReleaseConstants.cs
new file mode 100644
index 0000000..9922ef9
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/ReleaseConstants.cs
@@ -0,0 +1,23 @@
+namespace analyticsLibrary.ReleaseTooling;
+
+public static class ReleaseConstants
+{
+    public const string LegacyDeprecationMessage =
+        "This package is legacy and is no longer maintained";
+
+    public const string PrereleaseTestingDeprecationMessage =
+        "This pre-release package was published for pull request validation only. Install the latest stable release instead.";
+
+    public static readonly string[] PackageIds =
+    [
+        "analyticsLibrary.Core",
+        "analyticsLibrary.Algorithms",
+        "analyticsLibrary.Statistics",
+        "analyticsLibrary.Excel",
+        "analyticsLibrary.Access",
+        "analyticsLibrary.Hadoop",
+        "analyticsLibrary",
+    ];
+
+    public const string PrereleaseLabelPrefix = "-beta.pr-";
+}
diff --git a/src/analyticsLibrary.ReleaseTooling/VersionDeprecationPlanner.cs b/src/analyticsLibrary.ReleaseTooling/VersionDeprecationPlanner.cs
new file mode 100644
index 0000000..2dd1e4e
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/VersionDeprecationPlanner.cs
@@ -0,0 +1,39 @@
+using NuGet.Versioning;
+
+namespace analyticsLibrary.ReleaseTooling;
+
+public static class VersionDeprecationPlanner
+{
+    public static bool IsCiBetaPrerelease(string versionString)
+    {
+        if (string.IsNullOrWhiteSpace(versionString))
+        {
+            return false;
+        }
+
+        if (!NuGetVersion.TryParse(versionString, out var v) || !v.IsPrerelease)
+        {
+            return false;
+        }
+
+        return versionString.Contains(ReleaseConstants.PrereleaseLabelPrefix, StringComparison.OrdinalIgnoreCase);
+    }
+
+    public static bool IsOlderStableThan(string versionString, NuGetVersion releaseVersion)
+    {
+        if (!NuGetVersion.TryParse(versionString, out var v))
+        {
+            return false;
+        }
+
+        if (v.IsPrerelease)
+        {
+            return false;
+        }
+
+        return v < releaseVersion;
+    }
+
+    public static NuGetVersion? TryParseReleaseVersion(string versionString) =>
+        NuGetVersion.TryParse(versionString, out var v) ? v : null;
+}
diff --git a/src/analyticsLibrary.ReleaseTooling/analyticsLibrary.ReleaseTooling.csproj b/src/analyticsLibrary.ReleaseTooling/analyticsLibrary.ReleaseTooling.csproj
new file mode 100644
index 0000000..251d4a1
--- /dev/null
+++ b/src/analyticsLibrary.ReleaseTooling/analyticsLibrary.ReleaseTooling.csproj
@@ -0,0 +1,12 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <RootNamespace>analyticsLibrary.ReleaseTooling</RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="NuGet.Versioning" />
+  </ItemGroup>
+</Project>
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/FlatContainerIndexParserTests.cs b/tests/analyticsLibrary.ReleaseTooling.Tests/FlatContainerIndexParserTests.cs
new file mode 100644
index 0000000..aafac55
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/FlatContainerIndexParserTests.cs
@@ -0,0 +1,26 @@
+using analyticsLibrary.ReleaseTooling;
+
+namespace analyticsLibrary.ReleaseTooling.Tests;
+
+public class FlatContainerIndexParserTests
+{
+    [Fact]
+    public void ParseVersions_extracts_ordered_strings()
+    {
+        const string json = """
+            {"versions":["1.0.0","2.0.0-beta.pr-1.2"]}
+            """;
+
+        var v = FlatContainerIndexParser.ParseVersions(json);
+
+        Assert.Equal(new[] { "1.0.0", "2.0.0-beta.pr-1.2" }, v);
+    }
+
+    [Fact]
+    public void ParseVersions_missing_array_returns_empty()
+    {
+        const string json = """{"other":[]}""";
+
+        Assert.Empty(FlatContainerIndexParser.ParseVersions(json));
+    }
+}
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/GlobalUsings.cs b/tests/analyticsLibrary.ReleaseTooling.Tests/GlobalUsings.cs
new file mode 100644
index 0000000..c802f44
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/GlobalUsings.cs
@@ -0,0 +1 @@
+global using Xunit;
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetFlatContainerTests.cs b/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetFlatContainerTests.cs
new file mode 100644
index 0000000..c59d322
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetFlatContainerTests.cs
@@ -0,0 +1,27 @@
+using System.Net;
+using System.Net.Http;
+using analyticsLibrary.ReleaseTooling;
+
+namespace analyticsLibrary.ReleaseTooling.Tests;
+
+public class NuGetFlatContainerTests
+{
+    [Fact]
+    public async Task Flat_container_index_for_core_has_versions_array()
+    {
+        var handler = new StubHttpMessageHandler(_ =>
+            new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("""{"versions":["1.0.0","2.0.0"]}""")
+            });
+        using var http = new HttpClient(handler);
+        var versions = await NuGetFlatContainerHttp.GetPublishedVersionsAsync(http, "analyticsLibrary.Core");
+        Assert.NotEmpty(versions);
+    }
+
+    private sealed class StubHttpMessageHandler(Func<HttpRequestMessage, HttpResponseMessage> handler) : HttpMessageHandler
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) =>
+            Task.FromResult(handler(request));
+    }
+}
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetGalleryDeprecationApiTests.cs b/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetGalleryDeprecationApiTests.cs
new file mode 100644
index 0000000..31e71e7
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/NuGetGalleryDeprecationApiTests.cs
@@ -0,0 +1,28 @@
+using System.Net.Http;
+using analyticsLibrary.ReleaseTooling;
+
+namespace analyticsLibrary.ReleaseTooling.Tests;
+
+public class NuGetGalleryDeprecationApiTests
+{
+    [Fact]
+    public void CreateDeprecationRequest_uses_put_form_urlencoded()
+    {
+        using var req = NuGetGalleryDeprecationApi.CreateDeprecationRequest(
+            "Some.Package",
+            new[] { "1.0.0", "1.0.1" },
+            isLegacy: true,
+            hasCriticalBugs: false,
+            isOther: false,
+            "msg",
+            "Some.Package",
+            "2.0.0",
+            "fake-key");
+
+        Assert.Equal(HttpMethod.Put, req.Method);
+        Assert.Contains("Some.Package", req.RequestUri!.AbsoluteUri, StringComparison.OrdinalIgnoreCase);
+        Assert.True(req.Headers.Contains("X-NuGet-ApiKey"));
+        Assert.NotNull(req.Content);
+        Assert.Equal("application/x-www-form-urlencoded", req.Content.Headers.ContentType!.MediaType);
+    }
+}
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/VersionDeprecationPlannerTests.cs b/tests/analyticsLibrary.ReleaseTooling.Tests/VersionDeprecationPlannerTests.cs
new file mode 100644
index 0000000..1e9b2e5
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/VersionDeprecationPlannerTests.cs
@@ -0,0 +1,33 @@
+using analyticsLibrary.ReleaseTooling;
+using NuGet.Versioning;
+
+namespace analyticsLibrary.ReleaseTooling.Tests;
+
+public class VersionDeprecationPlannerTests
+{
+    [Theory]
+    [InlineData("2.0.0-beta.pr-6.2", true)]
+    [InlineData("2.0.0-beta", false)]
+    [InlineData("2.0.0", false)]
+    [InlineData("2.0.0-rc.1", false)]
+    public void IsCiBetaPrerelease_matches_pr_build_suffix(string version, bool expected) =>
+        Assert.Equal(expected, VersionDeprecationPlanner.IsCiBetaPrerelease(version));
+
+    [Fact]
+    public void IsOlderStableThan_excludes_prerelease_and_current()
+    {
+        var rel = NuGetVersion.Parse("3.0.0");
+        Assert.True(VersionDeprecationPlanner.IsOlderStableThan("2.0.0", rel));
+        Assert.False(VersionDeprecationPlanner.IsOlderStableThan("3.0.0", rel));
+        Assert.False(VersionDeprecationPlanner.IsOlderStableThan("3.0.1", rel));
+        Assert.False(VersionDeprecationPlanner.IsOlderStableThan("3.0.0-beta.pr-1.1", rel));
+    }
+
+    [Fact]
+    public void Legacy_message_constant_is_exact()
+    {
+        Assert.Equal(
+            "This package is legacy and is no longer maintained",
+            ReleaseConstants.LegacyDeprecationMessage);
+    }
+}
diff --git a/tests/analyticsLibrary.ReleaseTooling.Tests/analyticsLibrary.ReleaseTooling.Tests.csproj b/tests/analyticsLibrary.ReleaseTooling.Tests/analyticsLibrary.ReleaseTooling.Tests.csproj
new file mode 100644
index 0000000..7a609eb
--- /dev/null
+++ b/tests/analyticsLibrary.ReleaseTooling.Tests/analyticsLibrary.ReleaseTooling.Tests.csproj
@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <IsPackable>false</IsPackable>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <RootNamespace>analyticsLibrary.ReleaseTooling.Tests</RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="xunit" />
+    <PackageReference Include="xunit.runner.visualstudio">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\analyticsLibrary.ReleaseTooling\analyticsLibrary.ReleaseTooling.csproj" />
+  </ItemGroup>
+</Project>
diff --git a/tools/analyticsLibrary.NuGetMaintenance/Program.cs b/tools/analyticsLibrary.NuGetMaintenance/Program.cs
new file mode 100644
index 0000000..d270a29
--- /dev/null
+++ b/tools/analyticsLibrary.NuGetMaintenance/Program.cs
@@ -0,0 +1,167 @@
+using System.Net;
+using analyticsLibrary.ReleaseTooling;
+using NuGet.Versioning;
+
+if (args.Length < 2 || !string.Equals(args[0], "apply-deprecations", StringComparison.Ordinal))
+{
+    Console.Error.WriteLine("Usage: analyticsLibrary.NuGetMaintenance apply-deprecations <releaseVersion>");
+    return 1;
+}
+
+var releaseRaw = args[1];
+var release = VersionDeprecationPlanner.TryParseReleaseVersion(releaseRaw);
+if (release is null)
+{
+    Console.Error.WriteLine($"Invalid release version: {releaseRaw}");
+    return 1;
+}
+
+var apiKey = Environment.GetEnvironmentVariable("NUGET_API_KEY");
+if (string.IsNullOrWhiteSpace(apiKey))
+{
+    Console.Error.WriteLine("NUGET_API_KEY is not set.");
+    return 1;
+}
+
+using var http = new HttpClient();
+return await RunAsync(http, apiKey, release, CancellationToken.None).ConfigureAwait(false);
+
+static async Task<int> RunAsync(HttpClient http, string apiKey, NuGetVersion releaseVersion, CancellationToken cancellationToken)
+{
+    const int chunkSize = 40;
+    foreach (var packageId in ReleaseConstants.PackageIds)
+    {
+        IReadOnlyList<string> published;
+        try
+        {
+            published = await NuGetFlatContainerHttp.GetPublishedVersionsAsync(http, packageId, cancellationToken)
+                .ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            Console.Error.WriteLine($"Failed to list versions for {packageId}: {ex.Message}");
+            return 1;
+        }
+
+        if (published.Count == 0)
+        {
+            Console.WriteLine($"No published versions found for {packageId}; skipping.");
+            continue;
+        }
+
+        var betas = published.Where(VersionDeprecationPlanner.IsCiBetaPrerelease).ToList();
+        var legacyStables = published
+            .Where(v => VersionDeprecationPlanner.IsOlderStableThan(v, releaseVersion))
+            .ToList();
+
+        foreach (var chunk in Chunk(betas, chunkSize))
+        {
+            var code = await SendDeprecationAsync(
+                    http,
+                    apiKey,
+                    packageId,
+                    chunk,
+                    isLegacy: false,
+                    hasCriticalBugs: false,
+                    isOther: true,
+                    ReleaseConstants.PrereleaseTestingDeprecationMessage,
+                    releaseVersion,
+                    cancellationToken)
+                .ConfigureAwait(false);
+            if (code != 0)
+            {
+                return code;
+            }
+        }
+
+        foreach (var chunk in Chunk(legacyStables, chunkSize))
+        {
+            var code = await SendDeprecationAsync(
+                    http,
+                    apiKey,
+                    packageId,
+                    chunk,
+                    isLegacy: true,
+                    hasCriticalBugs: false,
+                    isOther: false,
+                    ReleaseConstants.LegacyDeprecationMessage,
+                    releaseVersion,
+                    cancellationToken)
+                .ConfigureAwait(false);
+            if (code != 0)
+            {
+                return code;
+            }
+        }
+    }
+
+    return 0;
+}
+
+static List<List<string>> Chunk(IReadOnlyList<string> items, int size)
+{
+    var chunks = new List<List<string>>();
+    for (var i = 0; i < items.Count; i += size)
+    {
+        var end = Math.Min(i + size, items.Count);
+        var chunk = new List<string>(end - i);
+        for (var j = i; j < end; j++)
+        {
+            chunk.Add(items[j]);
+        }
+
+        chunks.Add(chunk);
+    }
+
+    return chunks;
+}
+
+static async Task<int> SendDeprecationAsync(
+    HttpClient http,
+    string apiKey,
+    string packageId,
+    IReadOnlyList<string> versions,
+    bool isLegacy,
+    bool hasCriticalBugs,
+    bool isOther,
+    string message,
+    NuGetVersion releaseVersion,
+    CancellationToken cancellationToken)
+{
+    if (versions.Count == 0)
+    {
+        return 0;
+    }
+
+    var normalizedRelease = releaseVersion.ToNormalizedString();
+    using var request = NuGetGalleryDeprecationApi.CreateDeprecationRequest(
+        packageId,
+        versions,
+        isLegacy,
+        hasCriticalBugs,
+        isOther,
+        message,
+        packageId,
+        normalizedRelease,
+        apiKey);
+
+    using var response = await http.SendAsync(request, cancellationToken).ConfigureAwait(false);
+    if (response.IsSuccessStatusCode)
+    {
+        Console.WriteLine(
+            $"Deprecated {versions.Count} version(s) of {packageId} (legacy={isLegacy}, other={isOther}).");
+        return 0;
+    }
+
+    var body = await response.Content.ReadAsStringAsync(cancellationToken).ConfigureAwait(false);
+    Console.Error.WriteLine(
+        $"NuGet deprecation failed for {packageId}: {(int)response.StatusCode} {response.ReasonPhrase}. Body: {body}");
+
+    if (response.StatusCode == HttpStatusCode.Forbidden)
+    {
+        Console.Error.WriteLine(
+            "Hint: ensure the API key allows package push/unlist and that the NuGet.org account has the manage-deprecation API enabled for this key.");
+    }
+
+    return 1;
+}
diff --git a/tools/analyticsLibrary.NuGetMaintenance/analyticsLibrary.NuGetMaintenance.csproj b/tools/analyticsLibrary.NuGetMaintenance/analyticsLibrary.NuGetMaintenance.csproj
new file mode 100644
index 0000000..4567cdb
--- /dev/null
+++ b/tools/analyticsLibrary.NuGetMaintenance/analyticsLibrary.NuGetMaintenance.csproj
@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <RootNamespace>analyticsLibrary.NuGetMaintenance</RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\analyticsLibrary.ReleaseTooling\analyticsLibrary.ReleaseTooling.csproj" />
+  </ItemGroup>
+</Project>