Stale Branch Detection
Identify git branches that are candidates for cleanup: merged-but-not-deleted and inactive branches with no recent commits.
Auto-Invoke Triggers
This skill automatically activates when:
- Keywords: "stale branches", "old branches", "branch cleanup", "prune branches", "dead branches", "unused branches", "inactive branches", "branch hygiene"
- Actions: "list branches to delete", "find stale branches", "clean up branches"
Arguments
--threshold <months>— Inactivity threshold in months (default: 3)--base <branch>— Base branch for merge check (default: main)--remote— Include remote branch analysis
Workflow
Execute each step below using the Bash tool. This is a read-only skill — never delete branches, only report findings.
Step 1: Validate Git Repository
git rev-parse --is-inside-work-tree 2>/dev/null || echo "NOT_A_GIT_REPO"If not a git repo, stop and inform the user.
Step 2: Parse Arguments
Parse $ARGUMENTS for:
--threshold N→ set THRESHOLD_MONTHS=N (default: 3)--base BRANCH→ set BASE_BRANCH=BRANCH (default: main)--remote→ set INCLUDE_REMOTE=true (default: false)
Verify the base branch exists:
git rev-parse --verify "$BASE_BRANCH" 2>/dev/null || echo "BASE_BRANCH_NOT_FOUND"If the base branch doesn't exist, try master as fallback. If neither exists, stop and inform the user.
Step 3: Calculate Inactivity Threshold
Cross-platform threshold date (epoch seconds):
# macOS
if [[ "$OSTYPE" == "darwin"* ]]; then
threshold=$(date -v-${THRESHOLD_MONTHS}m +%s)
else
# Linux
threshold=$(date -d "${THRESHOLD_MONTHS} months ago" +%s)
fi
echo "Threshold date (epoch): $threshold"Step 4: List Merged Branches
Find local branches already merged into the base branch (safe to delete):
echo "=== MERGED BRANCHES (safe to delete) ==="
merged_count=$(git branch --merged "$BASE_BRANCH" | grep -v "^\*" | grep -vw "$BASE_BRANCH" | wc -l | tr -d ' ')
git branch --merged "$BASE_BRANCH" | grep -v "^\*" | grep -vw "$BASE_BRANCH" | while IFS= read -r branch; do
branch="${branch## }"
last_commit_date=$(git log -1 --format='%ci' "$branch" 2>/dev/null | cut -d' ' -f1)
echo " $branch (last commit: ${last_commit_date:-unknown})"
done
if [ "$merged_count" -eq 0 ]; then
echo " (none)"
fi
echo "Total merged: $merged_count"Step 5: Detect Squash-Merged Branches
Detect branches whose changes are already in base via squash-and-merge or rebase-merge. Uses git cherry to compare patch-ids — if all commits have equivalents in base, the branch is squash-merged and safe to delete.
echo "=== SQUASH-MERGED BRANCHES (safe to delete) ==="
squash_count=0
squash_list=""
for branch in $(git for-each-ref --format='%(refname:short)' refs/heads/); do
[ "$branch" = "$BASE_BRANCH" ] && continue
# Skip branches already detected as merged
merged=$(git branch --merged "$BASE_BRANCH" | grep -w "$branch" | wc -l | tr -d ' ')
[ "$merged" -gt 0 ] && continue
# Count commits on branch since merge-base
merge_base=$(git merge-base "$BASE_BRANCH" "$branch" 2>/dev/null)
[ -z "$merge_base" ] && continue
unique_commits=$(git log --oneline "$merge_base".."$branch" --no-merges 2>/dev/null | wc -l | tr -d ' ')
[ "$unique_commits" -eq 0 ] && continue
# git cherry: + means NOT in base, - means equivalent exists in base
unpicked=$(git cherry "$BASE_BRANCH" "$branch" 2>/dev/null | grep '^+' | wc -l | tr -d ' ')
if [ "$unpicked" -eq 0 ]; then
relative=$(git log -1 --format='%cr' "$branch")
echo " $branch ($relative)"
squash_count=$((squash_count + 1))
squash_list="$squash_list|$branch"
fi
done
if [ "$squash_count" -eq 0 ]; then
echo " (none)"
fi
echo "Total squash-merged: $squash_count"Step 6: List Inactive Unmerged Branches
Find local branches NOT merged into base with no commits within the threshold period. Include ahead/behind counts:
echo "=== INACTIVE UNMERGED BRANCHES (review before delete) ==="
git for-each-ref --sort=committerdate --format='%(refname:short) %(committerdate:unix) %(committerdate:relative)' refs/heads/ | while IFS= read -r line; do
branch=$(echo "$line" | awk '{print $1}')
timestamp=$(echo "$line" | awk '{print $2}')
relative=$(echo "$line" | cut -d' ' -f3-)
# Skip base branch, current branch, and squash-merged branches
[ "$branch" = "$BASE_BRANCH" ] && continue
echo "$squash_list" | grep -qw "$branch" && continue
# Check if branch is inactive (older than threshold)
if [[ "$timestamp" =~ ^[0-9]+$ ]] && [ "$timestamp" -lt "$threshold" ]; then
# Check if NOT merged
merged=$(git branch --merged "$BASE_BRANCH" | grep -w "$branch" | wc -l | tr -d ' ')
if [ "$merged" -eq 0 ]; then
# Get ahead/behind counts relative to base
counts=$(git rev-list --left-right --count "$BASE_BRANCH"..."$branch" 2>/dev/null)
behind=$(echo "$counts" | awk '{print $1}')
ahead=$(echo "$counts" | awk '{print $2}')
echo " $branch ($relative) [ahead $ahead, behind $behind]"
fi
fi
doneStep 7: Remote Branch Analysis (if --remote)
Only execute this step if --remote flag was provided.
Detect the remote for the base branch and fetch:
remote=$(git config --get "branch.$BASE_BRANCH.remote" 2>/dev/null || echo "origin")
if ! git fetch --prune 2>/dev/null; then
echo "Warning: Could not reach remote. Skipping remote analysis."
fiIf the fetch warning was shown, skip the rest of Step 7. Otherwise, continue:
List remote merged branches:
echo "=== REMOTE MERGED BRANCHES ==="
remote_merged_count=$(git branch -r --merged "$BASE_BRANCH" | grep -v "HEAD" | grep -vw "$BASE_BRANCH" | wc -l | tr -d ' ')
git branch -r --merged "$BASE_BRANCH" | grep -v "HEAD" | grep -vw "$BASE_BRANCH" | while IFS= read -r branch; do
branch="${branch## }"
last_commit_date=$(git log -1 --format='%ci' "$branch" 2>/dev/null | cut -d' ' -f1)
echo " $branch (last commit: ${last_commit_date:-unknown})"
done
if [ "$remote_merged_count" -eq 0 ]; then
echo " (none)"
fiList remote inactive unmerged branches:
echo "=== REMOTE INACTIVE UNMERGED BRANCHES ==="
git for-each-ref --sort=committerdate --format='%(refname:short) %(committerdate:unix) %(committerdate:relative)' "refs/remotes/$remote/" | grep -v "HEAD" | grep -vw "$BASE_BRANCH" | while IFS= read -r line; do
branch=$(echo "$line" | awk '{print $1}')
timestamp=$(echo "$line" | awk '{print $2}')
relative=$(echo "$line" | cut -d' ' -f3-)
if [[ "$timestamp" =~ ^[0-9]+$ ]] && [ "$timestamp" -lt "$threshold" ]; then
merged=$(git branch -r --merged "$BASE_BRANCH" | grep -w "$branch" | wc -l | tr -d ' ')
if [ "$merged" -eq 0 ]; then
echo " $branch ($relative)"
fi
fi
doneStep 8: Summary
Present a summary report:
current_branch=$(git branch --show-current)
total_local=$(git branch | wc -l | tr -d ' ')
merged_into_base=$(git branch --merged "$BASE_BRANCH" | grep -vw "$BASE_BRANCH" | wc -l | tr -d ' ')
echo "=== SUMMARY ==="
echo "Current branch: $current_branch"
echo "Base branch: $BASE_BRANCH"
echo "Inactivity threshold: $THRESHOLD_MONTHS months"
echo "Total local branches: $total_local"
echo "Merged into $BASE_BRANCH: $merged_into_base"
echo "Squash-merged (detected via git cherry): $squash_count"After the summary, suggest cleanup commands (but never execute them):
Cleanup commands (run manually):
Delete merged local: git branch -d <branch>
Delete unmerged local: git branch -D <branch>
Delete remote: git push origin --delete <branch>
Delete all merged: git branch --merged main | grep -v main | xargs git branch -dImportant Caveats
- Squash merges: Branches merged via squash-and-merge are detected using
git cherry(patch-id comparison). Edge cases where detection may fail: amended commits after squash, or partial cherry-picks. If a branch appears in "inactive unmerged" but you know it was squash-merged, verify withgit cherry main <branch>. - Read-only: This skill never deletes branches. Deletion commands are shown as suggestions only.
- Remote analysis: The
--remoteflag runsgit fetch --prunewhich contacts the remote. This requires network access.
Progressive Disclosure
For more details, see:
- WORKFLOW.md — Detailed 5-phase methodology
- EXAMPLES.md — Usage scenarios with sample output
- TROUBLESHOOTING.md — Common issues and solutions
Version
1.1.0