auto find next available local port

packages/node/meshnet_node/cli.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import argparse
+import socket
 import sys
 import time
 from pathlib import Path
@@ -49,6 +50,19 @@ def _run_node(cfg: dict) -> None:
         )
 
 
+def _first_available_port(host: str, start: int = 7000, attempts: int = 100) -> int:
+    """Return the first TCP port bindable on host, starting at start."""
+    bind_host = "" if host == "0.0.0.0" else host
+    for port in range(start, start + attempts):
+        with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+            try:
+                sock.bind((bind_host, port))
+            except OSError:
+                continue
+            return port
+    raise OSError(f"no available TCP port in range {start}-{start + attempts - 1}")
+
+
 def _cmd_default(args) -> int:
     """No subcommand: wizard if no config, else start with saved config."""
     from .config import load_config, save_config, merge_cli_overrides
@@ -145,7 +159,7 @@ def _cmd_start(args) -> int:
     # Build a transient config from flags (don't write to disk)
     cfg = dict(DEFAULTS)
     cfg["tracker_url"] = args.tracker
-    cfg["port"] = args.port
+    cfg["port"] = args.port if args.port is not None else _first_available_port(args.host)
     if args.model_id is None and "/" in args.model:
         cfg["model_hf_repo"] = args.model
         cfg["model_name"] = args.model.split("/")[-1]
@@ -236,7 +250,7 @@ def main() -> None:
     # start subcommand (legacy / backward-compat)
     start_cmd = subparsers.add_parser("start", help="Start node (legacy flags)")
     start_cmd.add_argument("--tracker", default="http://localhost:8080")
-    start_cmd.add_argument("--port", type=int, default=7000)
+    start_cmd.add_argument("--port", type=int)
     start_cmd.add_argument("--model", default="stub-model")
     start_cmd.add_argument("--model-id", help="HuggingFace repo ID")
     start_cmd.add_argument("--shard-start", type=int)

tests/test_mining_cli.py

@@ -3,6 +3,7 @@
 from __future__ import annotations
 
 import json
+import socket
 import sys
 import types
 from pathlib import Path
@@ -387,6 +388,43 @@ def test_legacy_start_treats_repo_model_as_model_id(monkeypatch):
     assert captured["model_id"] == "Qwen/Qwen2.5-0.5B-Instruct"
 
 
+def test_legacy_start_without_port_uses_next_available_port(monkeypatch):
+    """Omitting --port skips an occupied default port before startup loads the model."""
+    from meshnet_node.cli import main
+
+    captured = {}
+
+    def fake_run_startup(*args, **kwargs):
+        captured.update(kwargs)
+        class _FakeNode:
+            chat_completion_count = 0
+            def stop(self): pass
+        return _FakeNode()
+
+    occupied = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    occupied.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+    occupied.bind(("127.0.0.1", 7000))
+    occupied.listen(1)
+    try:
+        monkeypatch.setattr(sys, "argv", [
+            "meshnet-node", "start",
+            "--tracker", "http://192.168.0.179:8081",
+            "--model", "Qwen/Qwen2.5-0.5B-Instruct",
+            "--host", "127.0.0.1",
+        ])
+
+        with patch("meshnet_node.startup.run_startup", side_effect=fake_run_startup):
+            with patch("time.sleep", side_effect=KeyboardInterrupt):
+                try:
+                    main()
+                except SystemExit as exc:
+                    assert exc.code == 0
+    finally:
+        occupied.close()
+
+    assert captured["port"] == 7001
+
+
 def test_default_cli_passes_advertise_host(monkeypatch):
     """The documented no-subcommand LAN flag reaches startup."""
     from meshnet_node.cli import main