hermes-agent/tests/cli/test_cli_mcp_config_watch.py
Teknium 60092f728c fix(mcp): move auto-reload opt-out to top-level mcp: section + regression tests
Follow-up on the salvaged #67449: auxiliary.mcp is the side-LLM task
provider block (provider/model/timeout for MCP aux calls) — a watcher
behavior toggle doesn't belong there. Move it to a new top-level mcp:
runtime section and read it from the same freshly-parsed config.yaml the
watcher already diffs (no second load_config() per tick, and flipping the
toggle + editing mcp_servers in one edit behaves correctly).

Also adds a regression test for the salvaged #55701 false-positive fix:
${VAR} templates in mcp_servers made the raw-yaml-vs-expanded-snapshot
comparison permanently unequal, so ANY save_config_value() rewrite (e.g.
/reasoning changing agent.reasoning_effort) fired a full MCP reconnect.

Credits: @OYLFLMH (#55701 env-expand fix), @TurgutKural (#67449 opt-out).
2026-07-20 00:41:05 -07:00

235 lines
9.3 KiB
Python

"""Tests for automatic MCP reload when config.yaml mcp_servers section changes."""
import time
from pathlib import Path
from unittest.mock import MagicMock, patch
def _make_cli(tmp_path, mcp_servers=None, extra_config=None):
"""Create a minimal HermesCLI instance with mocked config."""
import cli as cli_mod
obj = object.__new__(cli_mod.HermesCLI)
cfg = {"mcp_servers": mcp_servers or {}}
if extra_config:
cfg.update(extra_config)
obj.config = cfg
obj._agent_running = False
obj._last_config_check = 0.0
obj._config_mcp_servers = mcp_servers or {}
cfg_file = tmp_path / "config.yaml"
cfg_file.write_text("mcp_servers: {}\n")
obj._config_mtime = cfg_file.stat().st_mtime
obj._reload_mcp = MagicMock()
obj._busy_command = MagicMock()
obj._busy_command.return_value.__enter__ = MagicMock(return_value=None)
obj._busy_command.return_value.__exit__ = MagicMock(return_value=False)
obj._slow_command_status = MagicMock(return_value="reloading...")
return obj, cfg_file
class TestMCPConfigWatch:
def test_no_change_does_not_reload(self, tmp_path):
"""If mtime and mcp_servers unchanged, _reload_mcp is NOT called."""
obj, cfg_file = _make_cli(tmp_path)
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_not_called()
def test_mtime_change_with_same_mcp_servers_does_not_reload(self, tmp_path):
"""If file mtime changes but mcp_servers is identical, no reload."""
import yaml
obj, cfg_file = _make_cli(tmp_path, mcp_servers={"fs": {"command": "npx"}})
# Write same mcp_servers but touch the file
cfg_file.write_text(yaml.dump({"mcp_servers": {"fs": {"command": "npx"}}}))
# Force mtime to appear changed
obj._config_mtime = 0.0
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_not_called()
def test_new_mcp_server_triggers_reload(self, tmp_path):
"""Adding a new MCP server to config triggers auto-reload."""
import yaml
obj, cfg_file = _make_cli(tmp_path, mcp_servers={})
# Simulate user adding a new MCP server to config.yaml
cfg_file.write_text(yaml.dump({"mcp_servers": {"github": {"url": "https://mcp.github.com"}}}))
obj._config_mtime = 0.0 # force stale mtime
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_called_once()
def test_removed_mcp_server_triggers_reload(self, tmp_path):
"""Removing an MCP server from config triggers auto-reload."""
import yaml
obj, cfg_file = _make_cli(tmp_path, mcp_servers={"github": {"url": "https://mcp.github.com"}})
# Simulate user removing the server
cfg_file.write_text(yaml.dump({"mcp_servers": {}}))
obj._config_mtime = 0.0
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_called_once()
def test_interval_throttle_skips_check(self, tmp_path):
"""If called within CONFIG_WATCH_INTERVAL, stat() is skipped."""
obj, cfg_file = _make_cli(tmp_path)
obj._last_config_check = time.monotonic() # just checked
with patch("hermes_cli.config.get_config_path", return_value=cfg_file), \
patch.object(Path, "stat") as mock_stat:
obj._check_config_mcp_changes()
mock_stat.assert_not_called()
obj._reload_mcp.assert_not_called()
def test_missing_config_file_does_not_crash(self, tmp_path):
"""If config.yaml doesn't exist, _check_config_mcp_changes is a no-op."""
obj, cfg_file = _make_cli(tmp_path)
missing = tmp_path / "nonexistent.yaml"
with patch("hermes_cli.config.get_config_path", return_value=missing):
obj._check_config_mcp_changes() # should not raise
obj._reload_mcp.assert_not_called()
def test_optout_disables_auto_reload(self, tmp_path, capsys):
"""When mcp.auto_reload_on_config_change is False, a changed
mcp_servers section must NOT trigger an automatic reload — but the
change is still detected and the user is told how to apply it.
This protects the provider prompt cache: every automatic reload
rebuilds the agent tool surface and invalidates cached prefixes.
The toggle is the top-level ``mcp:`` section in config.yaml, and the
watcher reads it from the same freshly-parsed file it diffs — so
flipping the toggle and editing mcp_servers in one edit behaves
correctly.
"""
import yaml
obj, cfg_file = _make_cli(
tmp_path,
mcp_servers={},
)
# Simulate a changed mcp_servers section with auto-reload opted out.
cfg_file.write_text(yaml.dump({
"mcp": {"auto_reload_on_config_change": False},
"mcp_servers": {"github": {"url": "https://mcp.github.com"}},
}))
obj._config_mtime = 0.0 # force stale mtime
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_not_called()
out = capsys.readouterr().out
assert "reload skipped" in out
assert "/reload-mcp" in out
assert "prompt cache" in out
def test_optout_updates_snapshot_so_reload_mcp_applies_cleanly(self, tmp_path):
"""After an opted-out change, the watcher must not re-notify every
tick: the snapshot is updated so the same content compares equal on
the next pass."""
import yaml
obj, cfg_file = _make_cli(tmp_path, mcp_servers={})
cfg_file.write_text(yaml.dump({
"mcp": {"auto_reload_on_config_change": False},
"mcp_servers": {"github": {"url": "https://mcp.github.com"}},
}))
obj._config_mtime = 0.0
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
# Second pass: same file content, new mtime — no reload, no change.
obj._last_config_check = 0.0
obj._config_mtime = 0.0
obj._check_config_mcp_changes()
obj._reload_mcp.assert_not_called()
assert obj._config_mcp_servers == {"github": {"url": "https://mcp.github.com"}}
def test_optout_path_is_top_level_mcp_not_auxiliary(self, tmp_path):
"""Regression guard: the opt-out toggle is the top-level
``mcp.auto_reload_on_config_change`` key, NOT ``auxiliary.mcp``
(which holds side-LLM task provider settings).
A config that sets ONLY ``auxiliary.mcp.auto_reload_on_config_change:
false`` must NOT disable the reload."""
import yaml
obj, cfg_file = _make_cli(
tmp_path,
mcp_servers={},
)
cfg_file.write_text(yaml.dump({
"auxiliary": {"mcp": {"auto_reload_on_config_change": False}},
"mcp_servers": {"github": {"url": "https://mcp.github.com"}},
}))
obj._config_mtime = 0.0
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
# Reload happened because the aux-task path is not the toggle.
obj._reload_mcp.assert_called()
def test_env_var_templates_do_not_false_positive_on_unrelated_saves(
self, tmp_path, monkeypatch, capsys
):
"""Regression for the '/reasoning triggers MCP reload' bug (#55701).
Init snapshots mcp_servers from the loaded config, which has been
through _expand_env_vars() — so ``${MCP_GH_API_KEY}`` is stored
expanded. The watcher re-parses the RAW yaml. Without expanding the
watcher side too, the comparison is always unequal whenever any
template is in use, so EVERY config.yaml rewrite (e.g.
save_config_value('agent.reasoning_effort', ...) from /reasoning)
fired a full MCP reconnect.
"""
import yaml
monkeypatch.setenv("MCP_GH_API_KEY", "sekrit-token")
raw_servers = {
"github": {
"url": "https://mcp.github.com",
"headers": {"Authorization": "Bearer ${MCP_GH_API_KEY}"},
}
}
expanded_servers = {
"github": {
"url": "https://mcp.github.com",
"headers": {"Authorization": "Bearer sekrit-token"},
}
}
# Init snapshot holds the EXPANDED form (as load_cli_config produces).
obj, cfg_file = _make_cli(tmp_path, mcp_servers=expanded_servers)
# Unrelated-key save: mcp_servers content identical (raw templates),
# only reasoning_effort changed — mtime moves.
cfg_file.write_text(yaml.dump({
"agent": {"reasoning_effort": "high"},
"mcp_servers": raw_servers,
}))
obj._config_mtime = 0.0
with patch("hermes_cli.config.get_config_path", return_value=cfg_file):
obj._check_config_mcp_changes()
obj._reload_mcp.assert_not_called()
assert "MCP server config changed" not in capsys.readouterr().out