diff --git a/.github/actions/build-cmake/action.yaml b/.github/actions/build-cmake/action.yaml
index bccaa938..314e00a6 100644
--- a/.github/actions/build-cmake/action.yaml
+++ b/.github/actions/build-cmake/action.yaml
@@ -23,10 +23,10 @@ runs:
   using: "composite"
   steps:
     - shell: bash
+      working-directory: ${{ inputs.build-path }}
       run: |
         # Source the container entrypoint script
         . /entrypoint.sh
-        cd "$GITHUB_WORKSPACE/$BUILD_PATH"
 
         # Determine parallel jobs
         if [ -n "$PARALLEL_JOBS" ]; then
@@ -47,8 +47,6 @@ runs:
         # Build
         cmake --build . $jobs_arg $target_arg
       env:
-        SOURCE_PATH: ${{ inputs.source-path }}
-        BUILD_PATH: ${{ inputs.build-path }}
         TARGET: ${{ inputs.target }}
         PARALLEL_JOBS: ${{ inputs.parallel-jobs }}
         CICOLOR_FORCE: 1
diff --git a/.github/actions/configure-cmake/action.yaml b/.github/actions/configure-cmake/action.yaml
index c0a2e717..42ce7b3a 100644
--- a/.github/actions/configure-cmake/action.yaml
+++ b/.github/actions/configure-cmake/action.yaml
@@ -43,11 +43,11 @@ runs:
   using: "composite"
   steps:
     - shell: bash
+      working-directory: ${{ inputs.build-path }}
       run: |
         # Source the container entrypoint script
         . /entrypoint.sh
 
-        cd "$GITHUB_WORKSPACE/$BUILD_PATH"
         SOURCE_DIR="$GITHUB_WORKSPACE/$SOURCE_PATH"
         echo "Configuring with CMake preset: $PRESET"
 
@@ -80,7 +80,6 @@ runs:
         echo "C++ compiler: $CPP_COMPILER"
       env:
         SOURCE_PATH: ${{ inputs.source-path }}
-        BUILD_PATH: ${{ inputs.build-path }}
         EXTRA_OPTIONS: ${{ inputs.extra-options }}
         ENABLE_FORM: ${{ inputs.enable-form }}
         FORM_ROOT_STORAGE: ${{ inputs.form-root-storage }}
diff --git a/.github/actions/generate-build-matrix/generate_matrix.py b/.github/actions/generate-build-matrix/generate_matrix.py
index a7d7e9f7..eb44d4cc 100644
--- a/.github/actions/generate-build-matrix/generate_matrix.py
+++ b/.github/actions/generate-build-matrix/generate_matrix.py
@@ -7,12 +7,10 @@
 
 def get_default_combinations(event_name, all_combinations):
     """Gets the default build combinations based on the GitHub event type."""
-    if event_name in ("push", "pull_request", "pull_request_target"):
+    if event_name in ("push", "pull_request", "pull_request_target", "workflow_dispatch"):
         return ["gcc/none"]
     elif event_name == "issue_comment":
         return ["gcc/none", "clang/none"]
-    elif event_name == "workflow_dispatch":
-        return all_combinations
     else:
         # Default to a minimal safe configuration for unknown events
         return ["gcc/none"]
diff --git a/.github/actions/run-change-detection/action.yaml b/.github/actions/run-change-detection/action.yaml
index 4a3278f7..0c5d23fc 100644
--- a/.github/actions/run-change-detection/action.yaml
+++ b/.github/actions/run-change-detection/action.yaml
@@ -42,6 +42,12 @@ runs:
       with:
         fetch-depth: 0
         path: ${{ inputs.checkout-path }}
+        # This action is never called from a pull_request_target workflow; all callers
+        # use pull_request, issue_comment, workflow_dispatch, or workflow_call triggers.
+        # Even if it were called from pull_request_target, the empty sparse checkout
+        # below ensures no files from the ref are materialized on disk — only git
+        # objects are fetched — so no code from the PR is ever executed.
+        # codeql[actions/pull-request-target-injection]
         ref: ${{ inputs.ref }}
         repository: ${{ inputs.repo }}
         persist-credentials: false
diff --git a/.github/workflows/clang-tidy-fix.yaml b/.github/workflows/clang-tidy-fix.yaml
index c35e5273..cffa27a8 100644
--- a/.github/workflows/clang-tidy-fix.yaml
+++ b/.github/workflows/clang-tidy-fix.yaml
@@ -111,19 +111,17 @@ jobs:
         if:
           needs.setup.outputs.tidy_checks == '' && (steps.download_fixes_check.outcome == 'success' ||
           steps.download_fixes_fix.outcome == 'success')
-        env:
-          CHECKOUT_PATH: ${{ needs.setup.outputs.checkout_path }}
+        working-directory: ${{ needs.setup.outputs.checkout_path }}
         run: |
           # The artifact preserves the build directory prefix in its path structure.
           FIXES_FILE=""
-          if [ -d fixes ]; then
-            FIXES_FILE=$(find fixes -name "clang-tidy-fixes.yaml" | head -1)
+          if [ -d "$GITHUB_WORKSPACE/fixes" ]; then
+            FIXES_FILE=$(find "$GITHUB_WORKSPACE/fixes" -name "clang-tidy-fixes.yaml" | head -1)
           fi
           if [ -n "$FIXES_FILE" ]; then
             echo "Applying fixes from existing artifact..."
             . /entrypoint.sh
             FIXES_DIR="$(realpath "${FIXES_FILE%/*}")"
-            cd "${CHECKOUT_PATH}"
             clang-apply-replacements "${FIXES_DIR}" || true
             echo "applied=true" >> "$GITHUB_OUTPUT"
           else
@@ -143,7 +141,6 @@ jobs:
           TIDY_CHECKS: ${{ needs.setup.outputs.tidy_checks }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE"
 
           CLANG_TIDY_OPTS="clang-tidy;--export-fixes=clang-tidy-fixes.yaml"
           if [ -n "$TIDY_CHECKS" ]; then
@@ -165,20 +162,16 @@ jobs:
 
       - name: Generate clang-tidy fixes using CMake build
         if: steps.apply_from_artifact.outputs.applied != 'true'
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
           cmake --build . -j "$(nproc)" || true
 
       - name: Apply clang-tidy fixes
         if: steps.apply_from_artifact.outputs.applied != 'true'
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
           if [ -f clang-tidy-fixes.yaml ]; then
             clang-apply-replacements . || true
           fi
diff --git a/.github/workflows/cmake-build.yaml b/.github/workflows/cmake-build.yaml
index 3b2535f3..d68ea35e 100644
--- a/.github/workflows/cmake-build.yaml
+++ b/.github/workflows/cmake-build.yaml
@@ -21,7 +21,7 @@ run-name: "${{ github.actor }} building and testing ${{ github.repository }}"
           - `all` (run all combinations)
           - `all -clang/none -clang/valgrind` (run all except specified)
           - `+clang/none +clang/valgrind` (run default matrix plus specified)
-          Default (if empty): Run all except clang/none and clang/valgrind.
+          Default (if empty): Run `gcc/none`
         required: false
         default: ""
   workflow_call:
@@ -109,7 +109,12 @@ jobs:
 
   generate-matrix:
     needs: setup
-    if: needs.setup.result == 'success'
+    if: >
+      needs.setup.result == 'success' && (
+        github.event_name == 'workflow_dispatch' ||
+        inputs.skip-relevance-check ||
+        needs.setup.outputs.has_changes == 'true'
+      )
     runs-on: ubuntu-latest
     outputs:
       matrix: ${{ steps.generate.outputs.matrix }}
@@ -179,11 +184,9 @@ jobs:
 
       - name: Run tests
         if: matrix.sanitizer != 'valgrind'
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Running tests..."
           echo "::group::Running ctest"
@@ -198,11 +201,9 @@ jobs:
 
       - name: Run Valgrind tests
         if: matrix.sanitizer == 'valgrind'
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Running Valgrind tests..."
           echo "::group::Running ctest -T memcheck"
@@ -214,6 +215,20 @@ jobs:
             echo "⚠️ Valgrind tests failed, but the workflow will continue."
           fi
 
+  cmake-build-skipped:
+    needs: [setup]
+    if: >
+      needs.setup.result == 'success' && github.event_name != 'workflow_dispatch' &&
+      !inputs.skip-relevance-check && needs.setup.outputs.is_act != 'true' &&
+      needs.setup.outputs.has_changes != 'true'
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+
+    steps:
+      - name: No relevant C++ or CMake changes detected
+        run: echo "::notice::No relevant C++ or CMake changes detected; build skipped."
+
   build-complete:
     needs: [setup, build]
     if: >
@@ -233,7 +248,7 @@ jobs:
             **Result:** ${{ needs.build.result == 'success' && '✅ All builds and tests passed.'
               || needs.build.result == 'failure' && '❌ Some builds or tests failed.'
               || needs.build.result == 'cancelled' && '⚠️ Build was cancelled before completion.'
-              || needs.build.result == 'skipped' && 'ℹ️ Build job was skipped.'
+              || needs.build.result == 'skipped' && 'ℹ️ No relevant C++ or CMake changes detected; build skipped.'
               || format('ℹ️ Build job completed with status: {0}.', needs.build.result) }}
 
             See the [workflow run](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) for detailed results.
diff --git a/.github/workflows/coverage.yaml b/.github/workflows/coverage.yaml
index 0bc751dd..fafa41d3 100644
--- a/.github/workflows/coverage.yaml
+++ b/.github/workflows/coverage.yaml
@@ -162,14 +162,12 @@ jobs:
           build-path: ${{ needs.setup.outputs.build_path }}
 
       - name: Run tests with coverage
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Running tests with coverage..."
-          PROFILE_ROOT="$GITHUB_WORKSPACE/${BUILD_PATH}/test/profraw"
+          PROFILE_ROOT="$(pwd)/test/profraw"
           echo "Cleaning LLVM profile directory: $PROFILE_ROOT"
           rm -rf "$PROFILE_ROOT"
           mkdir -p "$PROFILE_ROOT"
@@ -189,11 +187,9 @@ jobs:
         id: report_gcc
         if: ${{ steps.coverage_options.outputs.compiler == 'gcc' }}
         shell: bash
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Generating coverage reports for GCC..."
           echo "::group::Running coverage-gcov target"
@@ -210,11 +206,9 @@ jobs:
         id: report_clang
         if: ${{ steps.coverage_options.outputs.compiler == 'clang' }}
         shell: bash
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Generating coverage reports for Clang..."
           echo "::group::Running coverage-llvm target"
@@ -231,11 +225,9 @@ jobs:
         id: report_python
         if: ${{ steps.report_gcc.outcome != 'skipped' || steps.report_clang.outcome != 'skipped' }}
         shell: bash
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           . /entrypoint.sh
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
 
           echo "➡️ Generating Python coverage report..."
           echo "::group::Running coverage-python target"
@@ -258,10 +250,8 @@ jobs:
         id: coverage_outputs
         if: ${{ steps.report_gcc.outcome != 'skipped' || steps.report_clang.outcome != 'skipped' }}
         shell: bash
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
           if [ -f coverage.xml ]; then
             echo "has_coverage_xml=true" >> "$GITHUB_OUTPUT"
           else
@@ -292,14 +282,12 @@ jobs:
       - name: Prepare coverage artifact bundle
         if: ${{ steps.report_gcc.outcome != 'skipped' || steps.report_clang.outcome != 'skipped' }}
         shell: bash
-        env:
-          BUILD_PATH: ${{ needs.setup.outputs.build_path }}
+        working-directory: ${{ needs.setup.outputs.build_path }}
         run: |
           set -euo pipefail
           ARTIFACT_DIR="$GITHUB_WORKSPACE/coverage-artifacts"
           rm -rf "$ARTIFACT_DIR"
           mkdir -p "$ARTIFACT_DIR"
-          cd "$GITHUB_WORKSPACE/${BUILD_PATH}"
           for file in \
             coverage-llvm.txt \
             coverage-llvm.info \
diff --git a/.github/workflows/dependabot-auto-merge.yaml b/.github/workflows/dependabot-auto-merge.yaml
index 61ff9d02..adcb4125 100644
--- a/.github/workflows/dependabot-auto-merge.yaml
+++ b/.github/workflows/dependabot-auto-merge.yaml
@@ -67,14 +67,53 @@ jobs:
         # yamllint disable rule:line-length
         run: |
           set -o pipefail
-          if ! gh pr merge --auto --rebase "${PR_NUMBER}" --repo "$GITHUB_REPOSITORY" 2>&1 | tee /tmp/gh-output.txt; then
-            if grep -qE "auto-merge is already enabled|[Rr]equired.*status.*check|[Rr]equired approving review|[Rr]equired.*review" /tmp/gh-output.txt; then
-              echo "Auto-merge not enabled yet - this is expected when requirements are not met or already enabled"
-              exit 0
-            else
-              echo "Unexpected error enabling auto-merge:"
+
+          attempt_merge() {
+            gh pr merge --auto --rebase "${PR_NUMBER}" --repo "$GITHUB_REPOSITORY" 2>&1 | tee /tmp/gh-output.txt
+          }
+
+          if attempt_merge; then
+            exit 0
+          fi
+
+          # Not a real failure: requirements not yet met, or auto-merge already enabled.
+          if grep -qE "auto-merge is already enabled|[Rr]equired.*status.*check|[Rr]equired approving review|[Rr]equired.*review" /tmp/gh-output.txt; then
+            echo "Auto-merge not enabled yet - this is expected when requirements are not met or already enabled"
+            exit 0
+          fi
+
+          # The repository-level "Allow auto-merge" setting is off. Re-enable it and retry once.
+          # This can happen if the setting is accidentally toggled in the repository admin UI.
+          if grep -qF "Auto merge is not allowed for this repository" /tmp/gh-output.txt; then
+            echo "Repository Allow auto-merge is disabled; attempting to re-enable..."
+            if ! gh api "repos/${GITHUB_REPOSITORY}" --method PATCH --field allow_auto_merge=true > /dev/null; then
+              echo "Could not re-enable Allow auto-merge on the repository. Manual intervention required."
+              exit 1
+            fi
+            echo "Repository setting re-enabled; retrying..."
+            if ! attempt_merge; then
+              echo "Auto-merge still failed after re-enabling repository setting:"
               cat /tmp/gh-output.txt
               exit 1
             fi
+            exit 0
           fi
+
+          # Concurrent merge race: another PR merged while this one was being processed,
+          # moving the base branch. Request a Dependabot rebase to update this branch;
+          # this workflow re-triggers naturally via check_suite:completed when the rebased
+          # branch passes checks. With N concurrent Dependabot PRs, this converges in N-1
+          # rounds: each round merges one PR, and any PRs that fall behind again each get
+          # a fresh rebase request on the next trigger.
+          if grep -qF "Base branch was modified" /tmp/gh-output.txt; then
+            echo "Base branch was modified by a concurrent merge. Requesting Dependabot rebase..."
+            gh pr comment "${PR_NUMBER}" --repo "$GITHUB_REPOSITORY" --body "@dependabot rebase" || true
+            echo "Rebase requested; workflow will re-trigger when the rebased branch passes checks."
+            exit 0
+          fi
+
+          # Unexpected error.
+          echo "Unexpected error enabling auto-merge:"
+          cat /tmp/gh-output.txt
+          exit 1
         # yamllint enable