add-git-sync

name	add-git-sync
description	Add git-as-state hooks to an agent — auto-commits on Stop, rebases on SessionStart, snapshots on PreCompact. Gives agents durable cross-session memory through their own repo.
allowed-tools	Read, Write, Edit, Bash, Glob, Grep, AskUserQuestion
user-invocable	true
metadata	{"version":"1.0","created":"2026-04-21T00:00:00.000Z","author":"Ability.ai","changelog":["1.0: Initial version — installs git-as-state hooks (Stop auto-commit, SessionStart rebase, PreCompact snapshot) so an agent's own repo becomes durable cross-session memory"]}

Add Git Sync

ℹ️ First, set expectations: before anything else, print one short line with this skill's version and its most recent change — the top entry of metadata.changelog above — e.g. add-git-sync vX.Y — recent: <summary>. Then proceed.

Installs three hooks that turn the agent's own repo into its durable state layer:

Hook	Event	Job
git-session-start.sh	SessionStart (startup/resume)	Stash local drift → fetch → rebase onto remote branch → restore drift. Every session begins consistent with origin.
git-pre-compact.sh	PreCompact	Fast local commit so in-flight work survives context compaction. No push.
git-sync.sh	Stop (async)	git add -A → commit → push with rebase-on-reject retry. Drops .git/SYNC_FAILED if it can't reconcile; SessionStart surfaces the note next run.

Who this is for: any agent whose directory is its own git repo and benefits from cross-session continuity (Trinity-deployed agents, autonomous workers, long-running research agents). Not appropriate for agents nested inside a larger monorepo.

Escape hatches baked in:

• touch .git/NO_AUTOSYNC — disables all three hooks
• echo "..." > .git/SELF_SELECT_MSG — subagents write structured commit messages that survive the generic Stop-hook commit
• .git/SYNC_FAILED — propagates push failures forward to the next session

---

Process

Step 1: Preflight

Run from inside the target agent directory (or ask the user for the path). Verify:

# 1. CWD has CLAUDE.md (i.e. is an agent root)
[ -f CLAUDE.md ] || ask_user_for_agent_path

# 2. CWD is a git repo root (not nested). Resolve both sides with `pwd -P`
#    so macOS /tmp vs /private/tmp symlinks don't cause a false positive.
REPO_ROOT=$(git rev-parse --show-toplevel 2>/dev/null)
if [ -z "$REPO_ROOT" ]; then
  # Not a git repo — ask whether to init
  :
elif [ "$(cd "$REPO_ROOT" && pwd -P)" != "$(pwd -P)" ]; then
  # Nested inside a larger repo — refuse or offer local-only
  echo "ERROR: Agent dir is nested inside $REPO_ROOT. Hooks would push the wrong scope."
  exit 1
fi

# 3. Does .claude/settings.json exist? (create if missing)
# 4. Do any of the target hooks already exist? (if yes, diff and ask)

If no .git/: ask "Initialize git repo here?" If yes, git init.

Step 2: Ask configuration questions

Use AskUserQuestion with these three questions (in order):

Q1 — Sync mode

• remote-push (default) — Stop hook commits and pushes
• local-only — Stop hook commits but does not push (use when there's no remote or the agent is air-gapped)

Q2 — Remote and branch (only if Q1 = remote-push)

• Default: origin / main
• If git remote get-url origin fails, ask for the remote URL and set it up before continuing

Q3 — Commit co-author line

• Default: Co-Authored-By: Claude <[e-mail]>
• Or blank (no co-author)

Step 3: Install hook scripts

Templates live in this skill's templates/ directory. Copy to the agent's .claude/hooks/ with placeholder substitution:

SKILL_DIR="$(dirname "$0")"  # resolved at runtime
TEMPLATES="$SKILL_DIR/templates"
HOOKS_DIR="$AGENT_DIR/.claude/hooks"
mkdir -p "$HOOKS_DIR"

substitute() {
  local src="$1" dst="$2"
  sed -e "s|__BRANCH__|$BRANCH|g" \
      -e "s|__REMOTE__|$REMOTE|g" \
      -e "s|__COAUTHOR__|$COAUTHOR|g" \
      "$src" > "$dst"
  chmod +x "$dst"
}

if [ "$MODE" = "remote-push" ]; then
  substitute "$TEMPLATES/git-session-start.sh" "$HOOKS_DIR/git-session-start.sh"
  substitute "$TEMPLATES/git-pre-compact.sh"   "$HOOKS_DIR/git-pre-compact.sh"
  substitute "$TEMPLATES/git-sync.sh"          "$HOOKS_DIR/git-sync.sh"
else
  # local-only: no SessionStart (no remote to rebase from)
  substitute "$TEMPLATES/git-pre-compact.sh"   "$HOOKS_DIR/git-pre-compact.sh"
  substitute "$TEMPLATES/git-sync-local.sh"    "$HOOKS_DIR/git-sync.sh"
fi

Idempotency: before overwriting any existing hook file, diff content. If identical, skip silently. If different, show the diff and ask the user whether to overwrite.

Step 4: Merge into .claude/settings.json

Load existing settings (create {} if missing), merge the hooks block, write back. Use jq to keep the JSON canonical:

SETTINGS="$AGENT_DIR/.claude/settings.json"
[ -f "$SETTINGS" ] || echo '{}' > "$SETTINGS"

# Build the hooks JSON we want to ensure is present
NEW_HOOKS=$(jq -n --arg mode "$MODE" '{
  SessionStart: (if $mode == "remote-push" then [{
    matcher: "startup|resume",
    hooks: [{
      type: "command",
      command: "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/git-session-start.sh",
      timeout: 20,
      statusMessage: "Syncing from git..."
    }]
  }] else null end),
  PreCompact: [{
    hooks: [{
      type: "command",
      command: "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/git-pre-compact.sh",
      timeout: 15,
      statusMessage: "Snapshotting pre-compact..."
    }]
  }],
  Stop: [{
    hooks: [{
      type: "command",
      command: "\"$CLAUDE_PROJECT_DIR\"/.claude/hooks/git-sync.sh",
      timeout: 45,
      statusMessage: "Syncing to git...",
      async: true
    }]
  }]
} | with_entries(select(.value != null))')

# Merge: existing + new (new entries fill gaps; do NOT overwrite existing hook arrays
# for the same event — append instead, and warn the user if there are duplicates).
jq --argjson new "$NEW_HOOKS" '
  .hooks = (
    (.hooks // {}) as $existing
    | $new as $toAdd
    | reduce ($toAdd | keys_unsorted[]) as $event ($existing;
        .[$event] = (( .[$event] // [] ) + $toAdd[$event])
      )
  )
' "$SETTINGS" > "$SETTINGS.tmp" && mv "$SETTINGS.tmp" "$SETTINGS"

Idempotency check: before merging, scan existing hooks.<event> arrays for any entry whose command already points at .claude/hooks/git-*.sh. If found, skip that event and print [already installed].

Step 5: Append runtime-state exclusions to .gitignore

Add only entries not already present. Block-wrap with a header so it's clear what added them:

# --- agent-dev:add-git-sync runtime exclusions ---
.claude/projects/
.claude/statsig/
.claude/todos/
.claude/debug/
.claude/sessions/
.claude/shell-snapshots/
.claude/telemetry/
.claude/cache/
.claude/backups/
.claude.json
.mcp.json
.env
*.key
*.pem
credentials.json
# --- end add-git-sync ---

Before appending, grep each line against the existing .gitignore and skip duplicates. If the entire block header is already present, skip the section entirely.

Step 6: Add a section to the agent's CLAUDE.md

Check if a ## Git Sync or **[GIT SYNC (AUTOMATIC)]** section already exists. If yes, skip. If no, append:

---

## Git Sync (Automatic)

Three hooks manage git sync for this agent. Defined in `.claude/settings.json`, scripts in `.claude/hooks/`.

| Hook | Script | Purpose |
|---|---|---|
| `SessionStart` | `git-session-start.sh` | Auto-stash drift, fetch + rebase onto `<REMOTE>/<BRANCH>`, restore drift. |
| `PreCompact` | `git-pre-compact.sh` | Snapshot commit before compaction so mid-flight work survives context loss. No push. |
| `Stop` (async) | `git-sync.sh` | Commit staged files, push with rebase-on-reject retry (max 2). Honors `.git/SELF_SELECT_MSG` for structured commit messages. |

**Escape hatches:**
- `touch .git/NO_AUTOSYNC` — disable all three hooks until removed
- `echo "msg" > .git/SELF_SELECT_MSG` — override Stop-hook commit message (consumed after use)
- `.git/SYNC_FAILED` — written when push can't reconcile; surfaced in next SessionStart

**Design principle:** hooks enforce session-boundary consistency. Inside a session the agent is free; at boundaries (start / compact / stop) the repo reconciles.

Substitute <REMOTE> and <BRANCH> (or drop the SessionStart row entirely in local-only mode).

Step 7: Smoke test

Before declaring success, run:

# Syntax check each hook
for h in "$HOOKS_DIR"/git-*.sh; do
  bash -n "$h" || { echo "SYNTAX ERROR in $h"; exit 1; }
done

# settings.json parses
jq empty "$SETTINGS" || { echo "settings.json is invalid JSON"; exit 1; }

# .gitignore parses (just ensure it's readable)
[ -r "$AGENT_DIR/.gitignore" ]

Print a summary of what was added and what was skipped (idempotent no-ops).

Step 8: Print next steps

## Git Sync Installed

Mode: **<MODE>** (remote-push / local-only)
Remote: `<REMOTE>/<BRANCH>`  (if applicable)

### What's active
- SessionStart: auto-rebase onto remote
- PreCompact: safety snapshot
- Stop: auto-commit (and push, if remote-push)

### First-run checklist
1. Commit this setup: `git add .claude/ .gitignore CLAUDE.md && git commit -m "Add git-sync hooks"`
2. If remote-push: confirm `git remote -v` points at the right repo
3. Trigger a test: make a trivial edit, let the session end, verify a Heartbeat commit appears

### Disable temporarily
`touch .git/NO_AUTOSYNC` — re-enable by deleting the file.

---

Notes

• Prerequisite: jq must be installed (it's used by every hook and by this skill's settings merge). Check with command -v jq in Step 1; bail with install instructions if missing.
• Monorepo guard: the preflight refuses to install when the agent dir is nested inside a larger repo. The user can either pull the agent into its own repo or pick local-only mode at their own risk (the Stop hook would still commit to the wrong scope — safer to refuse).
• Co-author line: the __COAUTHOR__ placeholder is substituted as a single line. If the user wants multi-line sign-offs, they can edit git-sync.sh directly post-install.
• Re-running is safe. Every write checks for prior state. Running the skill twice produces no diff on the second run.