lock.sh

#!/bin/bash
# lock.sh — agent lock manager
# Usage:
#   ./lock.sh acquire <file> <agent-slug>         acquire lock before editing
#   ./lock.sh release <file> <agent-slug>         release lock after done
#   ./lock.sh wait    <file> <pane> <agent-slug>  register as waiting
#   ./lock.sh status                              show all locks and waiters
#   ./lock.sh check   <file>                      exit 0 if free, exit 1 if locked
#   ./lock.sh heartbeat <file> <agent-slug>       update heartbeat timestamp
#   ./lock.sh cleanup                             remove stale locks (>15 min no heartbeat)

set -e
LOCK_FILE=".agent-locks.json"
STALE_MINUTES=15

# ensure lock file exists and is valid
if [ ! -f "$LOCK_FILE" ]; then
  echo '{"schema_version":"1","locks":[],"waiting":[]}' > "$LOCK_FILE"
fi

# validate JSON before any operation
python3 -c "import json; json.load(open('$LOCK_FILE'))" 2>/dev/null || {
  echo "⚠ $LOCK_FILE is corrupt. Resetting."
  echo '{"schema_version":"1","locks":[],"waiting":[]}' > "$LOCK_FILE"
}

NOW=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

case $1 in
  acquire)
    FILE=$2; AGENT=$3
    if [ -z "$FILE" ] || [ -z "$AGENT" ]; then
      echo "Usage: $0 acquire <file> <agent-slug>"; exit 1
    fi
    python3 - <<EOF
import json, sys
data = json.load(open("$LOCK_FILE"))
locks = data.get("locks", [])
# check if already locked by someone else
for l in locks:
    if l["file"] == "$FILE" and l["agent"] != "$AGENT":
        print(f"✗ LOCKED by {l['agent']} since {l['locked_since']}")
        sys.exit(1)
# check if we already hold it
for l in locks:
    if l["file"] == "$FILE" and l["agent"] == "$AGENT":
        print(f"✓ Already held by $AGENT")
        sys.exit(0)
# acquire
locks.append({
    "file": "$FILE",
    "agent": "$AGENT",
    "locked_since": "$NOW",
    "heartbeat": "$NOW",
    "read_safe": False
})
data["locks"] = locks
# remove from waiting if present
data["waiting"] = [w for w in data.get("waiting", []) if not (w["file"] == "$FILE" and w["agent"] == "$AGENT")]
json.dump(data, open("$LOCK_FILE", "w"), indent=2)
print(f"✓ Lock acquired: $FILE by $AGENT")
EOF
    ;;

  release)
    FILE=$2; AGENT=$3
    if [ -z "$FILE" ] || [ -z "$AGENT" ]; then
      echo "Usage: $0 release <file> <agent-slug>"; exit 1
    fi
    python3 - <<EOF
import json
data = json.load(open("$LOCK_FILE"))
before = len(data.get("locks", []))
data["locks"] = [l for l in data.get("locks", []) if not (l["file"] == "$FILE" and l["agent"] == "$AGENT")]
after = len(data["locks"])
json.dump(data, open("$LOCK_FILE", "w"), indent=2)
if before > after:
    print(f"✓ Lock released: $FILE by $AGENT")
else:
    print(f"⚠ No lock found for $FILE by $AGENT (already released?)")
EOF
    ;;

  wait)
    FILE=$2; PANE=$3; AGENT=$4
    if [ -z "$FILE" ] || [ -z "$PANE" ] || [ -z "$AGENT" ]; then
      echo "Usage: $0 wait <file> <pane> <agent-slug>"; exit 1
    fi
    python3 - <<EOF
import json
data = json.load(open("$LOCK_FILE"))
waiting = data.get("waiting", [])
# avoid duplicate wait entries
for w in waiting:
    if w["file"] == "$FILE" and w["agent"] == "$AGENT":
        print(f"⚠ Already waiting for $FILE")
        exit(0)
waiting.append({
    "file": "$FILE",
    "pane": "$PANE",
    "agent": "$AGENT",
    "waiting_since": "$NOW"
})
data["waiting"] = waiting
json.dump(data, open("$LOCK_FILE", "w"), indent=2)
print(f"✓ Registered as waiting: $AGENT waiting for $FILE (pane $PANE)")
print(f"  Master watcher will resume you when the lock clears.")
EOF
    ;;

  check)
    FILE=$2
    if [ -z "$FILE" ]; then
      echo "Usage: $0 check <file>"; exit 1
    fi
    python3 - <<EOF
import json, sys
data = json.load(open("$LOCK_FILE"))
for l in data.get("locks", []):
    if l["file"] == "$FILE":
        print(f"LOCKED by {l['agent']} since {l['locked_since']}")
        sys.exit(1)
print("FREE")
sys.exit(0)
EOF
    ;;

  heartbeat)
    FILE=$2; AGENT=$3
    if [ -z "$FILE" ] || [ -z "$AGENT" ]; then
      echo "Usage: $0 heartbeat <file> <agent-slug>"; exit 1
    fi
    python3 - <<EOF
import json
data = json.load(open("$LOCK_FILE"))
updated = False
for l in data.get("locks", []):
    if l["file"] == "$FILE" and l["agent"] == "$AGENT":
        l["heartbeat"] = "$NOW"
        updated = True
json.dump(data, open("$LOCK_FILE", "w"), indent=2)
print(f"{'✓ Heartbeat updated' if updated else '⚠ Lock not found'}: $FILE by $AGENT")
EOF
    ;;

  cleanup)
    python3 - <<EOF
import json
from datetime import datetime, timezone, timedelta
data = json.load(open("$LOCK_FILE"))
cutoff = datetime.now(timezone.utc) - timedelta(minutes=$STALE_MINUTES)
stale = []
active = []
for l in data.get("locks", []):
    ts_str = l.get("heartbeat") or l.get("locked_since", "")
    try:
        ts = datetime.fromisoformat(ts_str.replace("Z", "+00:00"))
        if ts < cutoff:
            stale.append(l)
        else:
            active.append(l)
    except:
        stale.append(l)
data["locks"] = active
json.dump(data, open("$LOCK_FILE", "w"), indent=2)
if stale:
    for s in stale:
        print(f"✓ Removed stale lock: {s['file']} by {s['agent']}")
else:
    print("✓ No stale locks found.")
EOF
    ;;

  status)
    python3 - <<EOF
import json
data = json.load(open("$LOCK_FILE"))
locks = data.get("locks", [])
waiting = data.get("waiting", [])
print(f"=== Locks ({len(locks)}) ===")
for l in locks:
    print(f"  {l['file']} — held by {l['agent']} since {l['locked_since']}")
print(f"=== Waiting ({len(waiting)}) ===")
for w in waiting:
    print(f"  {w['file']} — {w['agent']} in pane {w['pane']} since {w['waiting_since']}")
EOF
    ;;

  *)
    echo "Usage: $0 <acquire|release|wait|check|heartbeat|cleanup|status> [args]"
    exit 1
    ;;
esac