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#!/usr/bin/env python3
"""Enumerate cross-agent destinations: local projects + tailnet peers.
See cross-agent-discover.md. Local: scan ~/projects/*/.ai/. Peers: read
peers.toml, SSH-probe each for reachability. --enumerate-remote optionally
runs `ls -d ~/projects/*/.ai/` over SSH to list remote projects.
Cache results for 5 min at ~/.cache/cross-agent-comms/discovery.json so
repeated invocations don't re-probe.
HALT: prints a banner; otherwise continues.
"""
from __future__ import annotations
import argparse
import datetime as _dt
import json
import os
import subprocess
import sys
import time
import tomllib
from pathlib import Path
CONFIG_DIR = Path.home() / ".config" / "cross-agent-comms"
PEERS_TOML = CONFIG_DIR / "peers.toml"
HALT_FILE = CONFIG_DIR / "HALT"
CACHE_DIR = Path.home() / ".cache" / "cross-agent-comms"
CACHE_FILE = CACHE_DIR / "discovery.json"
CACHE_TTL_SECONDS = 300
EXIT_OK = 0
EXIT_GENERAL = 1
EXIT_PEERS_TOML = 1
def err(msg: str) -> None:
print(msg, file=sys.stderr)
def render_banner_if_halt() -> None:
if not HALT_FILE.exists():
return
try:
reason = HALT_FILE.read_text().strip()
except OSError:
reason = "(HALT file unreadable; treated as halted)"
print("⚠ HALT ACTIVE — cross-agent comms paused")
if reason:
print(f" reason: {reason}")
print()
def enumerate_local_projects() -> list[str]:
projects_dir = Path.home() / "projects"
if not projects_dir.is_dir():
return []
found = []
for child in sorted(projects_dir.iterdir()):
if child.is_dir() and (child / ".ai").is_dir():
found.append(child.name)
return found
def load_peers() -> dict:
if not PEERS_TOML.exists():
return {"peers": {}}
try:
return tomllib.loads(PEERS_TOML.read_text())
except (tomllib.TOMLDecodeError, OSError) as e:
err(f"cannot parse peers.toml: {e}")
sys.exit(EXIT_PEERS_TOML)
def probe_peer_reachability(host: str, ssh_user: str | None) -> tuple[bool, str | None]:
"""Run a short SSH probe with BatchMode=yes (no interactive prompt)."""
target = f"{ssh_user}@{host}" if ssh_user else host
try:
result = subprocess.run(
["ssh", "-o", "ConnectTimeout=2", "-o", "BatchMode=yes", target, "true"],
capture_output=True,
text=True,
timeout=5,
)
except (FileNotFoundError, subprocess.TimeoutExpired):
return False, "ssh probe failed"
if result.returncode == 0:
return True, None
return False, (result.stderr.strip().splitlines() or [f"exit {result.returncode}"])[-1]
def enumerate_remote_projects(host: str, ssh_user: str | None) -> list[str] | None:
target = f"{ssh_user}@{host}" if ssh_user else host
try:
result = subprocess.run(
[
"ssh", "-o", "ConnectTimeout=3", "-o", "BatchMode=yes", target,
"ls -d ~/projects/*/.ai/ 2>/dev/null",
],
capture_output=True,
text=True,
timeout=10,
)
except (FileNotFoundError, subprocess.TimeoutExpired):
return None
if result.returncode != 0:
return None
projects = []
for line in result.stdout.splitlines():
# Each line looks like /home/<user>/projects/<name>/.ai/
parts = line.rstrip("/").split("/")
if len(parts) >= 2 and parts[-1] == ".ai":
projects.append(parts[-2])
return projects
def read_cache() -> dict | None:
if not CACHE_FILE.exists():
return None
try:
age = time.time() - CACHE_FILE.stat().st_mtime
if age > CACHE_TTL_SECONDS:
return None
return json.loads(CACHE_FILE.read_text())
except (OSError, json.JSONDecodeError):
return None
def write_cache(payload: dict) -> None:
CACHE_DIR.mkdir(parents=True, exist_ok=True)
CACHE_FILE.write_text(json.dumps(payload, indent=2))
def discover(peer_filter: str | None, enumerate_remote: bool) -> dict:
local = enumerate_local_projects()
peers_cfg = load_peers().get("peers", {})
peers_out = []
for name, cfg in sorted(peers_cfg.items()):
if peer_filter and name != peer_filter:
continue
host = cfg.get("host", name)
ssh_user = cfg.get("ssh_user")
reachable, error = probe_peer_reachability(host, ssh_user)
entry = {
"name": name,
"host": host,
"reachable": reachable,
}
if not reachable:
entry["error"] = error
if enumerate_remote and reachable:
entry["projects"] = enumerate_remote_projects(host, ssh_user) or []
peers_out.append(entry)
return {
"scanned_at": _dt.datetime.now(_dt.timezone.utc).isoformat(),
"halt_active": HALT_FILE.exists(),
"local": local,
"peers": peers_out,
}
def render_table(payload: dict, enumerate_remote: bool) -> None:
local = payload.get("local", [])
print(f"Local ({_local_hostname()}):")
if local:
wrapped = ", ".join(local)
print(f" {wrapped} [{len(local)} project{'s' if len(local) != 1 else ''}]")
else:
print(" (no projects with .ai/ found)")
print()
peers = payload.get("peers", [])
if not peers:
print("Peers (from peers.toml):")
print(" (no peers configured)")
return
print("Peers (from ~/.config/cross-agent-comms/peers.toml):")
for p in peers:
marker = "✓ reachable" if p.get("reachable") else f"✗ UNREACHABLE ({p.get('error', 'unknown')})"
print(f" {p['name']:<16} {p['host']:<24} {marker}")
if enumerate_remote and p.get("projects"):
wrapped = ", ".join(p["projects"])
print(f" projects: {wrapped}")
def _local_hostname() -> str:
import socket
return socket.gethostname().split(".")[0]
def main() -> int:
parser = argparse.ArgumentParser(description="Discover cross-agent destinations.")
parser.add_argument("--enumerate-remote", action="store_true",
help="SSH into each peer and list ~/projects/*/.ai/")
parser.add_argument("--no-cache", action="store_true", help="Skip cache; force fresh probe")
parser.add_argument("--peer", help="Limit to a single peer name from peers.toml")
parser.add_argument("--json", action="store_true", help="Machine-readable output")
args = parser.parse_args()
render_banner_if_halt()
payload = None
if not args.no_cache:
cached = read_cache()
if cached is not None:
# Honor --peer filter on cached payload.
if args.peer:
cached["peers"] = [p for p in cached.get("peers", []) if p["name"] == args.peer]
payload = cached
if payload is None:
payload = discover(args.peer, args.enumerate_remote)
if not args.no_cache and not args.peer:
# Only cache full (unfiltered) discoveries.
write_cache(payload)
if args.json:
print(json.dumps(payload, indent=2))
return EXIT_OK
render_table(payload, args.enumerate_remote)
return EXIT_OK
if __name__ == "__main__":
sys.exit(main())
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