Use symlinked source tree to restrict Codecov file discovery

Build a curated codecov_root/ with symlinks to only include/ (minus
contrib/ and flatbuffers/) and src/. Rewrite coverage.info paths to
relative so they resolve against the clean tree. This prevents Codecov
from discovering and displaying files outside the intended coverage scope.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: facontidavide

.github/workflows/cmake_ubuntu.yml

@@ -96,10 +96,28 @@ jobs:
              --ignore-errors unused
         lcov --list coverage.info
 
+    - name: Prepare coverage source tree
+      run: |
+        # Build a clean source tree with only the directories we want
+        # Codecov to see, excluding contrib/ and flatbuffers/
+        mkdir -p codecov_root/include/behaviortree_cpp
+        ln -s "$PWD/src" codecov_root/src
+        for item in include/behaviortree_cpp/*; do
+          name=$(basename "$item")
+          case "$name" in
+            contrib|flatbuffers) continue ;;
+          esac
+          ln -s "$PWD/$item" "codecov_root/include/behaviortree_cpp/$name"
+        done
+        # Rewrite absolute paths in coverage.info to be relative to codecov_root
+        sed -i "s|$PWD/||g" coverage.info
+
     - name: Upload coverage reports to Codecov
       uses: codecov/codecov-action@v5
       with:
         files: coverage.info
         flags: unittests
         disable_search: true
+        root_dir: codecov_root
+        plugins: noop
         token: ${{ secrets.CODECOV_TOKEN }}