#!/usr/bin/env python3
"""Reap orphaned/runaway processes that saturate the Nautilus box.

Two known offenders (2026-06-07):
  1. ``task-master-mcp`` (Node) — spawned by the Claude Code VSCode extension,
     orphaned to ``ppid=1`` when its session ends, then **balloons to ~3GB
     each**. They accrue as sessions cycle and exhaust RAM within minutes,
     risking the OOM-killer hitting Postgres/Paperclip. See memory
     ``project_taskmaster_mcp_memory_leak``.
  2. ``camoufox-bin`` (Firefox) — the X13 court-fetch browser. A fetch that
     hangs or is killed mid-flight can leave a stray browser orphaned to
     ``ppid=1``. Serial-only fetching means any ``ppid=1`` camoufox-bin is
     stale and safe to kill.

Safety: only processes **orphaned to ``ppid=1``** are reaped — a process still
owned by a live parent (an attached MCP server, or a browser a fetch is
actively using) is never touched. Pure ``/proc`` parsing, no psutil dependency.

Usage:
    python scripts/reap_orphan_procs.py            # one pass, print what was reaped
    python scripts/reap_orphan_procs.py --dry-run  # report only
    python scripts/reap_orphan_procs.py --loop 180 # daemon: reap every 180s
"""

from __future__ import annotations

import argparse
import os
import signal
import sys
import time

# Process-name substrings to reap when orphaned (ppid==1).
TARGETS = ("task-master-mcp", "camoufox-bin")


def _read(path: str) -> str:
    try:
        with open(path, "rb") as f:
            return f.read().decode("utf-8", "replace")
    except OSError:
        return ""


def _proc_info(pid: str) -> tuple[int, str, int] | None:
    """Return (ppid, cmdline, rss_kb) for a pid, or None if it vanished."""
    status = _read(f"/proc/{pid}/status")
    if not status:
        return None
    ppid, rss = 0, 0
    for line in status.splitlines():
        if line.startswith("PPid:"):
            try: ppid = int(line.split()[1])
            except (IndexError, ValueError): pass
        elif line.startswith("VmRSS:"):
            try: rss = int(line.split()[1])
            except (IndexError, ValueError): pass
    cmd = _read(f"/proc/{pid}/cmdline").replace("\x00", " ").strip()
    return ppid, cmd, rss


def find_orphans() -> list[tuple[str, str, int]]:
    """Return [(pid, cmd, rss_kb)] of ppid==1 processes matching TARGETS."""
    out = []
    for pid in os.listdir("/proc"):
        if not pid.isdigit():
            continue
        info = _proc_info(pid)
        if not info:
            continue
        ppid, cmd, rss = info
        if ppid == 1 and any(t in cmd for t in TARGETS):
            out.append((pid, cmd, rss))
    return out


def reap(dry_run: bool = False) -> int:
    orphans = find_orphans()
    freed_mb = 0
    for pid, cmd, rss in orphans:
        name = next((t for t in TARGETS if t in cmd), cmd[:30])
        freed_mb += rss // 1024
        if dry_run:
            print(f"[dry-run] would reap pid={pid} ({name}) rss={rss//1024}MB", flush=True)
            continue
        try:
            os.kill(int(pid), signal.SIGKILL)
            print(f"reaped pid={pid} ({name}) rss={rss//1024}MB", flush=True)
        except ProcessLookupError:
            pass
        except PermissionError:
            print(f"  permission denied for pid={pid} ({name})", flush=True)
    if orphans:
        print(f"{'would free' if dry_run else 'freed'} ~{freed_mb}MB "
              f"from {len(orphans)} orphan(s)", flush=True)
    return len(orphans)


def main() -> int:
    ap = argparse.ArgumentParser(description="Reap orphaned task-master-mcp / camoufox-bin")
    ap.add_argument("--dry-run", action="store_true", help="report only, kill nothing")
    ap.add_argument("--loop", type=int, default=0, metavar="SECONDS",
                    help="run forever, reaping every N seconds")
    args = ap.parse_args()
    if args.loop:
        print(f"reaper loop: every {args.loop}s targets={TARGETS}", flush=True)
        while True:
            try:
                reap(args.dry_run)
            except Exception as e:  # never let the daemon die
                print(f"reap error: {e}", flush=True)
            time.sleep(args.loop)
    else:
        reap(args.dry_run)
    return 0


if __name__ == "__main__":
    sys.exit(main())