feat(changelog): Detect nested merged branches

.github/actions/universal-detect-changes-and-generate-changelog/README.md

@@ -4,6 +4,8 @@ This GitHub Action detects changes since the last built commit and generates a c
 
 ## Features
 
+- ✅ **Nested Merge Detection**: Detects ALL merged branches including nested merges (e.g., B→A→develop reports both A and B)
+- ✅ **Smart Filtering**: Automatically filters out reverse merges (main→feature) used for conflict resolution
 - ✅ **Modular Design**: Split into separate bash scripts for better maintainability
 - ✅ **Customizable Cache Keys**: Support for custom cache key prefixes (format: `latest_builded_commit-` or `{prefix}-latest_builded_commit-`)
 - ✅ **GitHub-Native**: Leverages GitHub's built-in branch handling (no manual sanitization)
@@ -18,6 +20,8 @@ This GitHub Action detects changes since the last built commit and generates a c
 | `debug` | No | `false` | Enable debug mode for detailed logging |
 | `fallback_lookback` | No | `"24 hours"` | Time to look back for merge commits when no previous build commit is found |
 | `cache_key_prefix` | No | - | Custom prefix for cache keys. If not provided, will use `latest_builded_commit-`. If provided, format will be `{prefix}-latest_builded_commit-` |
+| `use_git_lfs` | No | `false` | Whether to download Git-LFS files during checkout |
+| `exclude_source_branches` | No | `"(main\|develop\|master)"` | Exclude merged commits of given branches. Regex pattern (ERE). Example: `"(release.*\|hotfix.*)"` |
 
 ## Outputs
 
@@ -28,6 +32,31 @@ This GitHub Action detects changes since the last built commit and generates a c
 | `merged_branches` | List of merged branch names |
 | `cache_key` | Cache key to store latest built commit for this branch |
 
+## Nested Merge Detection
+
+The action detects **all merged branches** including nested merges where one feature branch merges into another before merging to main.
+
+### How It Works
+
+**Example:** Branch B merges into branch A, then A merges into develop
+- **Output:** Both `feature-A` and `feature-B` are detected
+- **Filtering:** Reverse merges (e.g., `develop→feature-A` for conflict resolution) are automatically excluded
+
+### Implementation Details
+
+- **Branch Names**: Uses `git log --merges` (without `--first-parent`) to see all merge commits
+- **Changelog Messages**: Uses `git log --merges --first-parent` to follow only main branch history
+- **Filtering**: Excludes source branches via `grep -v "Merge branch '(EXCLUDE_SOURCE_BRANCHES)' into"`
+
+### Performance Considerations
+
+Removing `--first-parent` for branch detection means git traverses more of the commit graph:
+- **Impact**: Minimal for typical workflows (10-100 commits between builds)
+- **Large histories**: May add 1-2 seconds for repos with 1000+ commits in the range
+- **Recommendation**: Use `checkout_depth` to limit git history fetch depth if needed
+
+The performance tradeoff is generally acceptable given the improved accuracy in branch detection.
+
 ## Scripts
 
 ### `cache-keys.sh`
@@ -53,16 +82,17 @@ Determines commit range and skip build logic.
 - `to_commit`: Ending commit for changelog
 
 ### `generate-changelog.sh`
-Generates formatted changelog and branch names.
+Generates formatted changelog and branch names with nested merge detection.
 
 **Environment Variables:**
 - `FROM_COMMIT`: Starting commit
 - `TO_COMMIT`: Ending commit
+- `EXCLUDE_SOURCE_BRANCHES`: Regex pattern for excluding source branches (default: `(main|develop|master)`)
 - `DEBUG`: Debug mode flag
 
 **Outputs:**
-- `changelog_string`: Formatted changelog
-- `merged_branches`: List of merged branches
+- `changelog_string`: Formatted changelog (from main branch history only)
+- `merged_branches`: List of all merged branches (includes nested merges)
 
 ## Testing
 
@@ -78,6 +108,7 @@ The action includes comprehensive unit tests using BATS (Bash Automated Testing
 bats test/test_cache-keys.bats
 bats test/test_determine-range.bats
 bats test/test_generate-changelog.bats
+bats test/test_merged-branches.bats
 ```
 
 ### CI Testing
@@ -94,6 +125,9 @@ Tests run automatically on pull requests when relevant files change. The CI work
 - ✅ Commit range determination logic
 - ✅ Skip build decision making
 - ✅ Changelog generation and formatting
+- ✅ **Nested merge detection** (B→A→develop, C→B→A→develop)
+- ✅ **Reverse merge filtering** (conflict resolution exclusion)
+- ✅ **Custom target branch patterns**
 - ✅ Error handling and edge cases
 - ✅ Debug output functionality
 - ✅ Git command failure scenarios

.github/actions/universal-detect-changes-and-generate-changelog/action.yml

@@ -24,6 +24,10 @@ inputs:
     description: 'Whether to download Git-LFS files during checkout. Default is false.'
     type: boolean
     default: false
+  exclude_source_branches:
+    required: false
+    description: 'Exclude merged commits of given branches. Regex pattern (ERE). Example: "(release.*|hotfix.*)"'
+    default: "(main|develop|master)"
 
 outputs:
   skip_build:
@@ -91,3 +95,4 @@ runs:
         FROM_COMMIT: ${{ steps.determine_range.outputs.from_commit }}
         TO_COMMIT: ${{ steps.determine_range.outputs.to_commit }}
         DEBUG: ${{ inputs.debug }}
+        EXCLUDE_SOURCE_BRANCHES: ${{ inputs.exclude_source_branches }}

.github/actions/universal-detect-changes-and-generate-changelog/generate-changelog.sh

@@ -4,6 +4,7 @@
 # Global variables
 FROM_COMMIT="$FROM_COMMIT"
 TO_COMMIT="$TO_COMMIT"
+EXCLUDE_SOURCE_BRANCHES="${EXCLUDE_SOURCE_BRANCHES:-(main|develop|master)}"
 FORMATTED_CHANGELOG=""
 FORMATTED_BRANCH_NAMES=""
 
@@ -15,10 +16,14 @@ debug_log() {
 }
 
 # Get git log for changelog (commit messages)
+# NOTE: This intentionally uses --first-parent to follow the main branch history.
+# We only want changelog messages from direct merges to the main branch, not from
+# nested feature branch merges. Branch name detection (get_branch_names) does NOT
+# use --first-parent so it can detect nested branches.
 get_changelog() {
   local from_commit="$1"
   local to_commit="$2"
-  
+
   if [ "$from_commit" == "$to_commit" ]; then
     debug_log "FROM_COMMIT is same as HEAD. Using range HEAD~1..HEAD"
     git log --merges --first-parent --pretty=format:"%b" HEAD~1..HEAD 2>&1
@@ -34,14 +39,16 @@ get_changelog() {
 get_branch_names() {
   local from_commit="$1"
   local to_commit="$2"
-  
+
   if [ "$from_commit" == "$to_commit" ]; then
-    git log --merges --first-parent --pretty=format:"%s" HEAD~1..HEAD | \
+    git log --merges --pretty=format:"%s" HEAD~1..HEAD | \
+      grep -v -E "Merge branch '(${EXCLUDE_SOURCE_BRANCHES})' into" | \
       sed -e "s/^Merge branch '//" -e "s/^Merge pull request .* from //" -e "s/' into.*$//" -e "s/ into.*$//" | \
       grep -v '^$' 2>&1 || true
     return 0
   else
-    git log --merges --first-parent --pretty=format:"%s" "${from_commit}..${to_commit}" | \
+    git log --merges --pretty=format:"%s" "${from_commit}..${to_commit}" | \
+      grep -v -E "Merge branch '(${EXCLUDE_SOURCE_BRANCHES})' into" | \
       sed -e "s/^Merge branch '//" -e "s/^Merge pull request .* from //" -e "s/' into.*$//" -e "s/ into.*$//" | \
       grep -v '^$' 2>&1 || true
     return 0
@@ -135,11 +142,14 @@ main() {
 
   if [ "$FROM_COMMIT" == "$TO_COMMIT" ]; then
     debug_log "FROM_COMMIT is same as HEAD. Using range HEAD~1..HEAD"
+    # Changelog uses --first-parent to follow main branch history only
     raw_changelog=$(git log --merges --first-parent --pretty=format:"%b" HEAD~1..HEAD 2>&1)
     git_exit_code=$?
-    
+
     if [ $git_exit_code -eq 0 ]; then
-      raw_branch_names=$(git log --merges --first-parent --pretty=format:"%s" HEAD~1..HEAD 2>&1 | \
+      # Branch names do NOT use --first-parent to detect nested merges
+      raw_branch_names=$(git log --merges --pretty=format:"%s" HEAD~1..HEAD 2>&1 | \
+        grep -v -E "Merge branch '(${EXCLUDE_SOURCE_BRANCHES})' into" | \
         sed -e "s/^Merge branch '//" -e "s/^Merge pull request .* from //" -e "s/' into.*$//" -e "s/ into.*$//" | \
         grep -v '^$' 2>&1 || true)
       git_exit_code=0
@@ -148,11 +158,14 @@ main() {
     fi
   else
     debug_log "Using range ${FROM_COMMIT}..${TO_COMMIT}"
+    # Changelog uses --first-parent to follow main branch history only
     raw_changelog=$(git log --merges --first-parent --pretty=format:"%b" "${FROM_COMMIT}..${TO_COMMIT}" 2>&1)
     git_exit_code=$?
-    
+
     if [ $git_exit_code -eq 0 ]; then
-      raw_branch_names=$(git log --merges --first-parent --pretty=format:"%s" "${FROM_COMMIT}..${TO_COMMIT}" 2>&1 | \
+      # Branch names do NOT use --first-parent to detect nested merges
+      raw_branch_names=$(git log --merges --pretty=format:"%s" "${FROM_COMMIT}..${TO_COMMIT}" 2>&1 | \
+        grep -v -E "Merge branch '(${EXCLUDE_SOURCE_BRANCHES})' into" | \
         sed -e "s/^Merge branch '//" -e "s/^Merge pull request .* from //" -e "s/' into.*$//" -e "s/ into.*$//" | \
         grep -v '^$' 2>&1 || true)
       git_exit_code=0