squashing-history

name	squashing-history
description	Squashes all commits on the repo's default branch (main, falling back to master) to a single "Initial commit" with backup branch, integrity verification, and user confirmation before force push. Use when cleaning history or preparing for fresh start.
user-invocable	true
allowed-tools	AskUserQuestion, Bash(git:*), Bash(diff:*), Bash(rm:*), Bash(ls:*)
model	claude-haiku-4-5
context	fork

squashing-history

Squash all commits on the default branch to a single "Initial commit" while preserving code integrity.

Process

Phase 1: Pre-flight

Resolve the default branch (per the fleet's Default branch fallback rule — prefer main, fall back to master), then verify the working directory is clean and the current branch matches. Do not proceed otherwise.

BASE=$(git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's@^refs/remotes/origin/@@')
if [ -z "$BASE" ] && git show-ref --verify --quiet refs/remotes/origin/main;   then BASE=main;   fi
if [ -z "$BASE" ] && git show-ref --verify --quiet refs/remotes/origin/master; then BASE=master; fi
BASE="${BASE:-main}"

git status
CURRENT=$(git branch --show-current)
if [ "$CURRENT" != "$BASE" ]; then
  echo "Refusing to squash: current branch '$CURRENT' is not the default branch '$BASE'"
  exit 1
fi

Phase 2: Create Backup

BACKUP_BRANCH="backup-$(date +%Y%m%d-%H%M%S)"
git branch "$BACKUP_BRANCH"

Verify backup branch exists and points to current HEAD.

Phase 3: Capture Baseline

Record original HEAD SHA and commit count for reporting.

Phase 4: Squash

FIRST_COMMIT=$(git rev-list --max-parents=0 HEAD)
git reset --soft "$FIRST_COMMIT"
git commit -m "Initial commit"

Verify commit count is exactly 1.

Phase 5: Verify Integrity

git diff --ignore-submodules "$BACKUP_BRANCH"

Output must be completely empty. If any differences appear, rollback immediately with git reset --hard $BACKUP_BRANCH.

Phase 6: Confirm with User

Show summary (original count, backup branch name, integrity status) and ask for explicit confirmation via AskUserQuestion before force push.

Phase 7: Force Push

git push --force origin "$BASE"

Verify local and remote SHAs match after push.

Phase 8: Report

Report completion with backup branch name and rollback instructions.

See reference.md for retry loops and edge case handling.