Initial commit: multi-peer torrent download engine

Reactor/loop-pool engine with TCP/µTP/MSE transports, per-connection
pipelining, priority-driven piece selection with endgame, and the Python
FFI test harness.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

interop/seed_deluge.py

@@ -0,0 +1,82 @@
+from __future__ import annotations
+
+import argparse
+import os
+import signal
+import subprocess
+import time
+
+from common import touch_ready, wait_for_tcp
+
+
+def console(config: str, command: str, check: bool = True) -> subprocess.CompletedProcess:
+    return subprocess.run(
+        ["deluge-console", "-c", config, command],
+        text=True,
+        stdout=subprocess.PIPE,
+        stderr=subprocess.STDOUT,
+        check=check,
+        timeout=15,
+    )
+
+
+def main() -> int:
+    ap = argparse.ArgumentParser(description="Seed a fixture with Deluge.")
+    ap.add_argument("--torrent", required=True)
+    ap.add_argument("--data", required=True)
+    ap.add_argument("--port", type=int, required=True)
+    ap.add_argument("--daemon-port", type=int, default=58846)
+    args = ap.parse_args()
+
+    config = "/tmp/deluge-config"
+    os.makedirs(config, exist_ok=True)
+    proc = subprocess.Popen([
+        "deluged",
+        "-d",
+        "-c", config,
+        "-i", "0.0.0.0",
+        "-p", str(args.daemon_port),
+        "-L", "warning",
+    ])
+    stop = False
+
+    def _stop(signum, frame):
+        nonlocal stop
+        stop = True
+        proc.terminate()
+
+    signal.signal(signal.SIGTERM, _stop)
+    signal.signal(signal.SIGINT, _stop)
+
+    try:
+        wait_for_tcp("127.0.0.1", args.daemon_port, timeout=45)
+        settings = [
+            ("listen_ports", f"({args.port}, {args.port})"),
+            ("random_port", "False"),
+            ("dht", "False"),
+            ("lsd", "False"),
+            ("upnp", "False"),
+            ("natpmp", "False"),
+            ("add_paused", "False"),
+            ("download_location", args.data),
+        ]
+        for key, value in settings:
+            console(config, f"config -s {key} {value}")
+        console(config, f"add -p {args.data} {args.torrent}")
+        wait_for_tcp("127.0.0.1", args.port, timeout=45)
+        touch_ready()
+        print(f"Deluge seeding on {args.port}", flush=True)
+        while not stop and proc.poll() is None:
+            time.sleep(1)
+        return proc.returncode or 0
+    finally:
+        if proc.poll() is None:
+            proc.terminate()
+            try:
+                proc.wait(timeout=10)
+            except subprocess.TimeoutExpired:
+                proc.kill()
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())