cli: start MCP servers around chat and add /mcp slash command

tests/test_cli/test_mcp_cmd.py

@@ -0,0 +1,122 @@
+"""CLI slash ``/mcp`` command and MCP wiring in ``ReplState``."""
+
+from __future__ import annotations
+
+import json
+import sys
+from pathlib import Path
+from typing import TYPE_CHECKING
+
+import pytest
+import tomlkit
+
+from plyngent.cli.slash import handle_slash
+from plyngent.cli.state import ReplState
+from plyngent.config.models import DatabaseConfig, McpConfig, McpServerConfig, OpenAIProvider
+from plyngent.config.store import ConfigStore
+from plyngent.memory import MemoryStore
+from plyngent.runtime.mcp_client import McpManager
+
+if TYPE_CHECKING:
+    from collections.abc import AsyncIterator
+
+_FAKE_SERVER = Path(__file__).parent.parent / "test_runtime" / "mcp_fake_server.py"
+
+
+def _server_config(**overrides: object) -> McpServerConfig:
+    base: dict[str, object] = {
+        "command": sys.executable,
+        "args": [str(_FAKE_SERVER)],
+        "timeout": 5.0,
+    }
+    return McpServerConfig(**{**base, **overrides})  # type: ignore[arg-type]
+
+
+@pytest.fixture
+async def state(tmp_path: Path) -> AsyncIterator[ReplState]:
+    memory = await MemoryStore.open(DatabaseConfig())
+    provider = OpenAIProvider(access_key_or_token="sk-test")
+    config = ConfigStore(path=tmp_path / "plyngent.toml", document=tomlkit.document())
+    config.providers = {"local": provider}
+    st = ReplState(
+        config=config,
+        memory=memory,
+        workspace=tmp_path,
+        provider_name="local",
+        provider=provider,
+        model="gpt-test",
+        tools_enabled=False,
+    )
+    await st.new_session("t")
+    yield st
+    await memory.close()
+
+
+async def test_slash_mcp_list_without_manager(state: ReplState, capsys: pytest.CaptureFixture[str]) -> None:
+    assert await handle_slash(state, "/mcp") is True
+    assert "no servers configured" in capsys.readouterr().out
+    assert await handle_slash(state, "/mcp list") is True
+    assert "no servers configured" in capsys.readouterr().out
+
+
+async def test_slash_mcp_list_statuses(state: ReplState, capsys: pytest.CaptureFixture[str]) -> None:
+    manager = McpManager(McpConfig(servers={"fake": _server_config()}, disable=[]))
+    await manager.ensure_started()
+    state.mcp_manager = manager
+    try:
+        assert await handle_slash(state, "/mcp list") is True
+        out = capsys.readouterr().out
+        assert "fake" in out
+        assert "connected" in out
+        assert "tools=3" in out
+    finally:
+        await manager.aclose()
+
+
+async def test_slash_mcp_reconnect_connects_new_config(
+    state: ReplState,
+    capsys: pytest.CaptureFixture[str],
+    tmp_path: Path,
+) -> None:
+    # The fixture's config file does not exist yet; write one with an MCP server.
+    payload = (
+        "[mcp.servers.fake]\n"
+        f"command = {json.dumps(sys.executable)}\n"
+        f"args = [{json.dumps(str(_FAKE_SERVER))}]\n"
+        "timeout = 5.0\n"
+    )
+    _ = (tmp_path / "plyngent.toml").write_text(payload, encoding="utf-8")
+    assert await handle_slash(state, "/mcp reconnect") is True
+    try:
+        assert state.mcp_manager is not None
+        statuses = state.mcp_manager.statuses()
+        assert [name for name, _, _ in statuses] == ["fake"]
+        assert statuses[0][1] == "connected"
+        assert statuses[0][2] == 3
+        out = capsys.readouterr().out
+        assert "tools=off" in out
+        assert "fake" in out
+    finally:
+        if state.mcp_manager is not None:
+            await state.mcp_manager.aclose()
+
+
+async def test_mcp_tools_registered_on_tools_rebuild(state: ReplState) -> None:
+    manager = McpManager(McpConfig(servers={"fake": _server_config()}, disable=[]))
+    await manager.ensure_started()
+    state.mcp_manager = manager
+    try:
+        from plyngent.tools.catalog import catalog_scope
+
+        state.tools_enabled = True
+        with catalog_scope(empty=True):
+            state.rebuild_client()
+        registry = state.agent.tools
+        assert registry is not None
+        assert registry.get("mcp__fake__echo") is not None
+        assert registry.get("mcp__fake__fail") is not None
+        # Handler proxies to the live server subprocess.
+        out = await registry.execute("mcp__fake__echo", '{"text": "hi"}')
+        assert out == "echo: hi"
+    finally:
+        await manager.aclose()