template-jj/scripts/jj-hook.sh

#!/usr/bin/env bash
# jj-hook.sh — Claude Code hook client for jj-commitd
#
# Thin client that sends events to the jj-commitd daemon over a Unix socket.
# The daemon handles all jj operations (debounced commits, session tracking,
# reaping, bookmarks).
#
# If the daemon isn't running, session-start launches it automatically.
# If the daemon binary isn't found, falls back to simple file tracking
# with commit-at-session-end (the original behavior).
#
# Usage from Claude Code hooks:
#   scripts/jj-hook.sh session-start
#   scripts/jj-hook.sh session-end
#   scripts/jj-hook.sh post-edit
# Manual:
#   scripts/jj-hook.sh squash-wip
#   scripts/jj-hook.sh status
#   scripts/jj-hook.sh reap

set -uo pipefail

warn() { echo "jj-hook.sh: $*" >&2; }

# shellcheck source=_lib.sh
source "$(dirname "${BASH_SOURCE[0]}")/_lib.sh"

ACTION="${1:-}"
# SHA256-based repo ID — must match Go daemon's repoID() function
REPO_ID=$(printf '%s' "$REPO_ROOT" | shasum -a 256 | cut -c1-12)
SOCK="/tmp/jj-commitd-${REPO_ID}.sock"

# ── Daemon management ────────────────────────────────────────────

find_daemon() {
  local script_dir
  script_dir="$(dirname "${BASH_SOURCE[0]}")"

  for candidate in \
    "${script_dir}/../bin/jj-commitd" \
    "${script_dir}/../cmd/jj-commitd/jj-commitd" \
    "$(command -v jj-commitd 2>/dev/null || true)" \
    "${HOME}/go/bin/jj-commitd" \
    "${GOPATH:-${HOME}/go}/bin/jj-commitd"; do
    [ -n "$candidate" ] && [ -x "$candidate" ] && echo "$candidate" && return 0
  done
  return 1
}

ensure_daemon() {
  # Already running?
  if [ -S "$SOCK" ]; then
    if echo '{"event":"status"}' | nc -U -w1 "$SOCK" >/dev/null 2>&1; then
      return 0
    fi
    rm -f "$SOCK"
  fi

  local daemon
  daemon=$(find_daemon) || return 1

  REPO_ROOT="$REPO_ROOT" nohup "$daemon" </dev/null >>/tmp/jj-commitd-"${REPO_ID}".log 2>&1 &

  # Wait for socket (up to 2s)
  local attempts=0
  while [ ! -S "$SOCK" ] && [ "$attempts" -lt 20 ]; do
    sleep 0.1
    attempts=$((attempts + 1))
  done
  [ -S "$SOCK" ]
}

send_event() {
  echo "$1" | nc -U -w2 "$SOCK" 2>/dev/null || true
}

# ── Fallback (no daemon) ────────────────────────────────────────

fallback_post_edit() {
  local file="$1" session="$2"
  local tracking="/tmp/jj-claude-${REPO_ID}-${session}-files"
  if [ -f "$tracking" ]; then
    grep -qxF "$file" "$tracking" 2>/dev/null || echo "$file" >> "$tracking"
  else
    echo "$file" >> "$tracking"
  fi
}

fallback_session_end() {
  local session="$1"
  local tracking="/tmp/jj-claude-${REPO_ID}-${session}-files"
  if [ -f "$tracking" ] && [ -s "$tracking" ]; then
    if jj diff --summary 2>/dev/null | grep -q .; then
      jj commit -m "wip(claude:${session}): session end" 2>/dev/null || true
    fi
    rm -f "$tracking"
  fi
}

# ── Main dispatch ────────────────────────────────────────────────

case "$ACTION" in
  session-start)
    command -v jq >/dev/null 2>&1 || { cat >/dev/null; exit 0; }
    INPUT=$(cat)
    SID=$(printf '%s\n' "$INPUT" | jq -r '.session_id // empty' 2>/dev/null | head -c 8)
    [ -z "$SID" ] && SID="unknown"

    if ensure_daemon; then
      # Pass PPID (Claude Code process), not $$ (this short-lived script).
      send_event "{\"event\":\"session-start\",\"session_id\":\"${SID}\",\"repo_root\":\"${REPO_ROOT}\",\"pid\":${PPID}}"
    fi
    ;;

  session-end)
    command -v jq >/dev/null 2>&1 || { cat >/dev/null; exit 0; }
    INPUT=$(cat)
    SID=$(printf '%s\n' "$INPUT" | jq -r '.session_id // empty' 2>/dev/null | head -c 8)
    [ -z "$SID" ] && SID="unknown"

    if [ -S "$SOCK" ]; then
      send_event "{\"event\":\"session-end\",\"session_id\":\"${SID}\"}"
    else
      fallback_session_end "$SID"
    fi
    ;;

  post-edit)
    command -v jq >/dev/null 2>&1 || { cat >/dev/null; exit 0; }
    INPUT=$(cat)
    SID=$(printf '%s\n' "$INPUT" | jq -r '.session_id // empty' 2>/dev/null | head -c 8)
    [ -z "$SID" ] && SID="unknown"
    FILE_PATH=$(printf '%s\n' "$INPUT" | jq -r '.tool_input.file_path // empty' 2>/dev/null)

    if [ -n "$FILE_PATH" ]; then
      if [ -S "$SOCK" ]; then
        send_event "{\"event\":\"post-edit\",\"session_id\":\"${SID}\",\"file\":\"${FILE_PATH}\",\"repo_root\":\"${REPO_ROOT}\"}"
      else
        REL_PATH="${FILE_PATH#"${REPO_ROOT}"/}"
        fallback_post_edit "$REL_PATH" "$SID"
      fi
    fi
    ;;

  squash-wip)
    set -e
    command -v jj >/dev/null 2>&1 || { warn "jj not found"; exit 1; }
    cd "$REPO_ROOT"

    if jj diff --summary 2>/dev/null | grep -q .; then
      warn "uncommitted changes — commit or stash first"; exit 1
    fi

    MAIN_REV=$(jj log --no-graph -r 'main' -T 'commit_id.short(12)' 2>/dev/null)
    [ -z "$MAIN_REV" ] && { warn "no 'main' bookmark found"; exit 1; }

    WIP_REVS=$(jj log --no-graph -r 'main..@-' -T 'change_id.short(8) ++ "\n"' 2>/dev/null | grep -c . || true)
    [ "$WIP_REVS" -eq 0 ] && { echo "nothing to squash"; exit 0; }

    WIP_MESSAGES=$(jj log --no-graph -r 'main..@-' -T 'description.first_line() ++ "\n"' 2>/dev/null)
    SESSION_IDS=$(echo "$WIP_MESSAGES" | grep -oE 'claude:[a-z0-9_]+' | sort -u | sed 's/claude://' | paste -sd, -)
    SQUASH_MSG="wip(squashed): ${WIP_REVS} commits${SESSION_IDS:+ from sessions $SESSION_IDS}"
    LAST_WIP=$(jj log --no-graph -r '@-' -T 'change_id.short(12)' 2>/dev/null)

    jj new main -m "$SQUASH_MSG" 2>/dev/null || { warn "failed to create squash base"; exit 1; }
    jj restore --from "$LAST_WIP" 2>/dev/null || { warn "restore failed"; jj undo 2>/dev/null; exit 1; }
    jj commit -m "$SQUASH_MSG" 2>/dev/null || { warn "commit failed"; jj undo 2>/dev/null; exit 1; }
    jj abandon "all:main..${LAST_WIP}" 2>/dev/null || true

    for bm in $(jj bookmark list 2>/dev/null | grep -oE 'wip/claude-[^:]+' || true); do
      jj bookmark delete "$bm" 2>/dev/null || true
    done
    echo "squashed ${WIP_REVS} wip commits into one: ${SQUASH_MSG}"
    ;;

  status)
    if [ -S "$SOCK" ]; then
      send_event '{"event":"status"}'
    else
      echo "daemon not running (no socket at $SOCK)"
    fi
    ;;

  reap)
    if [ -S "$SOCK" ]; then
      send_event '{"event":"shutdown"}'
      echo "shutdown signal sent"
    else
      echo "daemon not running"
    fi
    ;;

  *)
    echo "Usage: jj-hook.sh {session-start|session-end|post-edit|squash-wip|status|reap}" >&2
    exit 1
    ;;
esac