diff --git a/.github/actions/github/branch-protection/lock/action.yml b/.github/actions/github/branch-protection/lock/action.yml
new file mode 100644
index 00000000..7a493cce
--- /dev/null
+++ b/.github/actions/github/branch-protection/lock/action.yml
@@ -0,0 +1,37 @@
+name: 'Lock branch'
+author: 'Pete Sramek'
+description: 'Apply branch protection to prevent direct pushes. Requires PRs with at least one approval.'
+inputs:
+  branch:
+    description: 'Branch name to lock.'
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: 'Lock branch ${{ inputs.branch }}'
+      shell: bash
+      env:
+        GH_TOKEN: ${{ github.token }}
+      run: |
+        if ! gh api --method PUT /repos/${{ github.repository }}/branches/${{ inputs.branch }}/protection \
+          --input - << 'EOF'
+        {
+          "required_status_checks": null,
+          "enforce_admins": false,
+          "required_pull_request_reviews": {
+            "dismiss_stale_reviews": true,
+            "require_code_owner_reviews": false,
+            "required_approving_review_count": 1
+          },
+          "restrictions": null,
+          "allow_force_pushes": false,
+          "allow_deletions": false,
+          "lock_branch": false
+        }
+        EOF
+        then
+          echo "::error::Failed to apply branch protection to '${{ inputs.branch }}'. Ensure the token has 'administration: write' permission and the branch exists."
+          exit 1
+        fi
+        echo "🔒 Branch '${{ inputs.branch }}' is now protected." >> $GITHUB_STEP_SUMMARY
diff --git a/.github/actions/github/branch-protection/unlock/action.yml b/.github/actions/github/branch-protection/unlock/action.yml
new file mode 100644
index 00000000..5bd37baa
--- /dev/null
+++ b/.github/actions/github/branch-protection/unlock/action.yml
@@ -0,0 +1,18 @@
+name: 'Unlock branch'
+author: 'Pete Sramek'
+description: 'Remove branch protection to allow a workflow to push directly. Always re-lock after the operation.'
+inputs:
+  branch:
+    description: 'Branch name to unlock.'
+    required: true
+
+runs:
+  using: composite
+  steps:
+    - name: 'Unlock branch ${{ inputs.branch }}'
+      shell: bash
+      env:
+        GH_TOKEN: ${{ github.token }}
+      run: |
+        gh api --method DELETE /repos/${{ github.repository }}/branches/${{ inputs.branch }}/protection || true
+        echo "🔓 Branch protection removed from '${{ inputs.branch }}'." >> $GITHUB_STEP_SUMMARY
diff --git a/.github/workflows/bump-version.yml b/.github/workflows/bump-version.yml
new file mode 100644
index 00000000..5fa8e79f
--- /dev/null
+++ b/.github/workflows/bump-version.yml
@@ -0,0 +1,157 @@
+name: 'Bump version'
+
+on:
+  workflow_dispatch:
+    inputs:
+      bump-type:
+        type: choice
+        options:
+          - 'minor'
+          - 'major'
+        description: 'Version bump type. Use ''minor'' to add features (keeps API files), ''major'' for breaking changes (resets API files).'
+        required: true
+
+permissions:
+  actions: read
+  contents: write
+  pull-requests: write
+  administration: write
+
+concurrency:
+  group: bump-version
+  cancel-in-progress: false
+
+env:
+  dotnet-sdk-version: '10.x'
+
+jobs:
+  detect-version:
+    name: 'Detect current version and calculate next'
+    runs-on: ubuntu-latest
+    outputs:
+      current-version: ${{ steps.detect.outputs.current-version }}
+      next-version: ${{ steps.calculate.outputs.next-version }}
+      target-branch: ${{ steps.calculate.outputs.target-branch }}
+    steps:
+      - name: 'Checkout main'
+        uses: actions/checkout@v6
+        with:
+          ref: main
+          fetch-depth: 0
+
+      - name: 'Detect highest release branch'
+        id: detect
+        run: |
+          git fetch origin
+          latest=$(git ls-remote --heads origin 'release/*' | grep -oP 'release/\K\d+\.\d+' | sort -V | tail -1)
+          if [[ -z "$latest" ]]; then
+            latest="0.0"
+          fi
+          echo "Detected current version: $latest"
+          echo "current-version=$latest" >> $GITHUB_OUTPUT
+
+      - name: 'Calculate next version'
+        id: calculate
+        run: |
+          current="${{ steps.detect.outputs.current-version }}"
+          major="${current%%.*}"
+          minor="${current##*.}"
+          if [[ "${{ inputs.bump-type }}" == "major" ]]; then
+            next_major=$((major + 1))
+            next_version="${next_major}.0"
+          else
+            next_minor=$((minor + 1))
+            next_version="${major}.${next_minor}"
+          fi
+          echo "Next version: $next_version"
+          echo "next-version=$next_version" >> $GITHUB_OUTPUT
+          echo "target-branch=develop/${next_version}" >> $GITHUB_OUTPUT
+
+  validate:
+    name: 'Validate bump'
+    needs: [detect-version]
+    runs-on: ubuntu-latest
+    steps:
+      - name: 'Checkout main'
+        uses: actions/checkout@v6
+        with:
+          ref: main
+          fetch-depth: 1
+
+      - name: 'Validate workflow is running from main'
+        if: ${{ github.ref_name != 'main' }}
+        run: |
+          echo "This workflow must be run from the 'main' branch. Current branch: '${{ github.ref_name }}'."
+          exit 1
+
+      - name: 'Validate target branch does not exist'
+        run: |
+          set +e
+          git ls-remote --exit-code --heads origin "${{ needs.detect-version.outputs.target-branch }}"
+          if [[ $? -eq 0 ]]; then
+            echo "Target branch '${{ needs.detect-version.outputs.target-branch }}' already exists."
+            exit 1
+          fi
+          set -e
+
+  create-branch:
+    name: 'Create ${{ needs.detect-version.outputs.target-branch }}'
+    needs: [detect-version, validate]
+    runs-on: ubuntu-latest
+    env:
+      next-version: ${{ needs.detect-version.outputs.next-version }}
+      target-branch: ${{ needs.detect-version.outputs.target-branch }}
+    steps:
+      - name: 'Checkout main'
+        uses: actions/checkout@v6
+        with:
+          ref: main
+          fetch-depth: 0
+
+      - name: 'Setup .NET ${{ env.dotnet-sdk-version }}'
+        uses: actions/setup-dotnet@v5
+        with:
+          dotnet-version: ${{ env.dotnet-sdk-version }}
+
+      - name: 'Configure git'
+        run: |
+          git config user.name "$(git log -n 1 --pretty=format:%an)"
+          git config user.email "$(git log -n 1 --pretty=format:%ae)"
+
+      - name: 'Create develop branch from main'
+        run: |
+          git checkout -b ${{ env.target-branch }}
+
+      - name: 'Reset PublicAPI files for major bump'
+        if: ${{ inputs.bump-type == 'major' }}
+        run: |
+          find . \( -name "PublicAPI.Shipped.txt" -o -name "PublicAPI.Unshipped.txt" \) | while read file; do
+            printf '\xef\xbb\xbf#nullable enable\n' > "$file"
+            echo "Reset: $file"
+          done
+
+      - name: 'Commit API file reset'
+        if: ${{ inputs.bump-type == 'major' }}
+        run: |
+          git add .
+          git diff --staged --quiet || git commit -m "Reset PublicAPI files for major version ${{ env.next-version }}"
+
+      - name: 'Push develop branch'
+        run: |
+          git push --set-upstream origin ${{ env.target-branch }}
+
+      - name: 'Write summary'
+        run: |
+          echo "## ✅ Branch created: \`${{ env.target-branch }}\`" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "| | |" >> $GITHUB_STEP_SUMMARY
+          echo "|---|---|" >> $GITHUB_STEP_SUMMARY
+          echo "| **Bump type** | ${{ inputs.bump-type }} |" >> $GITHUB_STEP_SUMMARY
+          echo "| **Previous version** | ${{ needs.detect-version.outputs.current-version }} |" >> $GITHUB_STEP_SUMMARY
+          echo "| **New version** | ${{ env.next-version }} |" >> $GITHUB_STEP_SUMMARY
+          echo "| **Target branch** | \`${{ env.target-branch }}\` |" >> $GITHUB_STEP_SUMMARY
+          if [[ "${{ inputs.bump-type }}" == "major" ]]; then
+            echo "| **API files** | Reset (major bump) |" >> $GITHUB_STEP_SUMMARY
+          else
+            echo "| **API files** | Preserved (minor bump) |" >> $GITHUB_STEP_SUMMARY
+          fi
diff --git a/.github/workflows/promote-branch.yml b/.github/workflows/promote-branch.yml
index 03df4b47..645d712c 100644
--- a/.github/workflows/promote-branch.yml
+++ b/.github/workflows/promote-branch.yml
@@ -21,6 +21,7 @@ permissions:
   id-token: write
   contents: write
   pull-requests: write
+  administration: write
 
 concurrency:
     group: 'promote-branch-${{ inputs.promotion-type }}-${{github.ref_name }}'
@@ -30,6 +31,7 @@ env:
   dotnet-sdk-version: '10.x'
   is-development-branch: ${{ startsWith(github.ref_name, 'develop') }}
   is-maintenance-branch: ${{ startsWith(github.ref_name, 'support') }}
+  is-preview-branch: ${{ startsWith(github.ref_name, 'preview') }}
 
 jobs:
   versioning:
@@ -159,10 +161,15 @@ jobs:
         run: |
           echo "Invalid promotion type ${{ inputs.promotion-type }}"
           exit 1
-      - name: 'Validate current branch'
-        if: ${{ (env.is-development-branch == 'false') && (env.is-maintenance-branch == 'false') }}
+      - name: 'Validate source branch for preview promotion'
+        if: ${{ env.promotion-type == 'preview' && (env.is-development-branch == 'false') && (env.is-maintenance-branch == 'false') }}
         run: |
-          echo "Invalid current branch '${{ github.ref_name }}'"
+          echo "Preview promotion requires a 'develop/**' or 'support/**' source branch. Current branch: '${{ github.ref_name }}'"
+          exit 1
+      - name: 'Validate source branch for release promotion'
+        if: ${{ env.promotion-type == 'release' && env.is-preview-branch == 'false' }}
+        run: |
+          echo "Release promotion requires a 'preview/**' source branch. Current branch: '${{ github.ref_name }}'"
           exit 1
       - name: 'Validate default and current branch'
         if: ${{ env.base-branch == env.current-branch }}
@@ -206,6 +213,11 @@ jobs:
           git switch ${{ needs.workflow-variables.outputs.base-branch }}
           git checkout -b ${{ needs.workflow-variables.outputs.target-branch }} origin/${{ needs.workflow-variables.outputs.target-branch }} || git checkout -b ${{ needs.workflow-variables.outputs.target-branch }}
           git push --set-upstream origin ${{ needs.workflow-variables.outputs.target-branch }}
+      - name: 'Lock target branch'
+        if: ${{ needs.workflow-variables.outputs.target-branch-exists == 'false' }}
+        uses: './.github/actions/github/branch-protection/lock'
+        with:
+          branch: ${{ needs.workflow-variables.outputs.target-branch }}
       - name: 'Create PR: "Promote ${{ env.current-branch }} to ${{ env.target-branch }}"'
         if: ${{ needs.workflow-variables.outputs.pull-request-exists == 'false' }}
         env:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 30379531..cfdc85a7 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -257,3 +257,60 @@ jobs:
           release-version: ${{ env.release-version }}
           is-preview: ${{ env.is-preview }}
           notes-start-tag: ${{ steps.determine-notes-start-tag.outputs.notes-start-tag }}
+
+  merge-to-main:
+    name: 'Merge ${{ github.ref_name }} into main'
+    needs: [workflow-variables, release, versioning]
+    if: ${{ needs.workflow-variables.outputs.is-release == 'true' }}
+    runs-on: ubuntu-latest
+    env:
+      GH_TOKEN: ${{ github.token }}
+      current-branch: ${{ github.ref_name }}
+      current-version: ${{ needs.versioning.outputs.friendly-version }}
+    steps:
+      - name: 'Checkout ${{ github.head_ref || github.ref }}'
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: 'Detect if current branch is the latest release'
+        id: detect-latest
+        run: |
+          git fetch origin
+          latest_version=$(git ls-remote --heads origin 'release/*' | grep -oP 'release/\K\d+\.\d+' | sort -V | tail -1)
+          current_version=$(echo "${{ env.current-version }}" | grep -oP '^\d+\.\d+')
+          echo "Latest release branch version: $latest_version"
+          echo "Current version (normalized): $current_version"
+          if [[ "$latest_version" == "$current_version" ]]; then
+            echo "is-latest=true" >> $GITHUB_OUTPUT
+          else
+            echo "is-latest=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: 'Check if PR to main already exists'
+        id: check-pr
+        if: ${{ steps.detect-latest.outputs.is-latest == 'true' }}
+        run: |
+          pr_count=$(gh pr list --head "${{ env.current-branch }}" --base main --state open --limit 1 --json id --jq '. | length')
+          if [[ $pr_count -gt 0 ]]; then
+            echo "pr-exists=true" >> $GITHUB_OUTPUT
+          else
+            echo "pr-exists=false" >> $GITHUB_OUTPUT
+          fi
+
+      - name: 'Create PR: Merge ${{ env.current-branch }} into main'
+        if: ${{ steps.detect-latest.outputs.is-latest == 'true' && steps.check-pr.outputs.pr-exists == 'false' }}
+        run: |
+          gh pr create \
+            --title "Merge ${{ env.current-branch }} into main" \
+            --fill \
+            --base main \
+            --head "${{ env.current-branch }}"
+
+      - name: 'Write merge summary'
+        run: |
+          if [[ "${{ steps.detect-latest.outputs.is-latest }}" == "true" ]]; then
+            echo "✅ PR created to merge **${{ env.current-branch }}** into **main**." >> $GITHUB_STEP_SUMMARY
+          else
+            echo "⏭️ Skipped merge to main: **${{ env.current-branch }}** is not the highest release branch." >> $GITHUB_STEP_SUMMARY
+          fi