Add runtime capability scaffolding and align docs

tests/test_vm_network.py

@@ -0,0 +1,60 @@
+from __future__ import annotations
+
+import subprocess
+from pathlib import Path
+
+import pytest
+
+from pyro_mcp.vm_network import NetworkConfig, TapNetworkManager
+
+
+def test_tap_network_manager_allocation_disabled_by_default(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    monkeypatch.delenv("PYRO_VM_ENABLE_NETWORK", raising=False)
+    manager = TapNetworkManager()
+    config = manager.allocate("abcdef123456")
+    assert manager.enabled is False
+    assert config.tap_name == "pyroabcdef12"
+    assert config.guest_ip.startswith("172.29.")
+    metadata = manager.to_metadata(config)
+    assert metadata["network_enabled"] == "false"
+
+
+def test_tap_network_manager_network_info() -> None:
+    manager = TapNetworkManager(enabled=False)
+    config = NetworkConfig(
+        vm_id="abcdef123456",
+        tap_name="pyroabcdef12",
+        guest_ip="172.29.100.2",
+        gateway_ip="172.29.100.1",
+        subnet_cidr="172.29.100.0/24",
+        mac_address="06:00:ab:cd:ef:12",
+    )
+    info = manager.network_info(config)
+    assert info["tap_name"] == "pyroabcdef12"
+    assert info["outbound_connectivity_expected"] is False
+
+
+def test_tap_network_manager_enabled_runs_host_commands() -> None:
+    commands: list[list[str]] = []
+
+    def runner(command: list[str]) -> subprocess.CompletedProcess[str]:
+        commands.append(command)
+        return subprocess.CompletedProcess(command, 0, "", "")
+
+    manager = TapNetworkManager(enabled=True, runner=runner)
+    config = manager.allocate("abcdef123456")
+    manager.cleanup(config)
+    assert commands[0][:4] == ["ip", "tuntap", "add", "dev"]
+    assert commands[-1][:3] in (["ip", "link", "del"], ["nft", "delete", "table"])
+
+
+def test_tap_network_manager_missing_host_support(monkeypatch: pytest.MonkeyPatch) -> None:
+    monkeypatch.setattr(Path, "exists", lambda self: False if str(self) == "/dev/net/tun" else True)
+    manager = TapNetworkManager(
+        enabled=True,
+        runner=lambda command: subprocess.CompletedProcess(command, 0, "", ""),
+    )
+    with pytest.raises(RuntimeError, match="/dev/net/tun"):
+        manager.allocate("abcdef123456")