b29c200801
* fix(mcp): invalidate tool prompt cache on connect/disconnect/error get_tool_descriptions_for_prompt cached its result keyed only on (disabled_map, len(_tools)). If a server reconnects with the same tool count (or transitions to error state), the cache was never busted — the agent received stale tool descriptions for the new connection state. Add a _generation counter incremented on every structural change (successful connect, disconnect, connection error) and include it in the cache key. * test(mcp): regression test for _generation cache invalidation
72 lines
2.8 KiB
Python
72 lines
2.8 KiB
Python
"""Regression test: McpManager._generation must bust the tool prompt cache
|
|
when a server connects/disconnects with the same tool count.
|
|
|
|
Before the fix, cache_key was (disabled_map, len(_tools)). A reconnect that
|
|
preserved the tool count left the stale description in place. After the fix
|
|
the _generation counter is included so any structural change invalidates it.
|
|
"""
|
|
import asyncio
|
|
|
|
from src.mcp_manager import McpManager
|
|
|
|
|
|
def _make_mgr():
|
|
return McpManager()
|
|
|
|
|
|
def _inject_tools(mgr, server_id: str, tools: list):
|
|
"""Directly populate internal dicts as _connect_stdio would after success."""
|
|
mgr._tools[server_id] = tools
|
|
mgr._connections[server_id] = {"status": "connected", "name": server_id}
|
|
|
|
|
|
# ---------------------------------------------------------------------------
|
|
# _generation increments on disconnect
|
|
# ---------------------------------------------------------------------------
|
|
|
|
def test_generation_increments_on_disconnect():
|
|
mgr = _make_mgr()
|
|
assert mgr._generation == 0
|
|
_inject_tools(mgr, "srv1", [{"name": "tool_a"}])
|
|
mgr._generation += 1 # simulate connect increment
|
|
|
|
gen_before = mgr._generation
|
|
asyncio.run(mgr.disconnect_server("srv1"))
|
|
assert mgr._generation == gen_before + 1
|
|
|
|
|
|
# ---------------------------------------------------------------------------
|
|
# Core cache-invalidation regression: stale description after reconnect
|
|
# ---------------------------------------------------------------------------
|
|
|
|
def test_prompt_cache_busted_after_disconnect_same_tool_count():
|
|
"""The stale-cache bug: two different servers each have 1 tool.
|
|
After the first disconnects and the second connects, the cache must
|
|
reflect the new server's tools, not the old one's description.
|
|
"""
|
|
mgr = _make_mgr()
|
|
|
|
# Connect server A with one tool
|
|
_inject_tools(mgr, "srv_a", [{"name": "tool_alpha", "description": "Alpha tool",
|
|
"inputSchema": {"type": "object", "properties": {}}}])
|
|
mgr._generation += 1 # simulated successful connect
|
|
|
|
desc_a = mgr.get_tool_descriptions_for_prompt()
|
|
assert "tool_alpha" in desc_a
|
|
|
|
# Disconnect A — same tool count (1) as what follows
|
|
asyncio.run(mgr.disconnect_server("srv_a")) # bumps _generation
|
|
|
|
# Connect server B with a *different* tool but same count (1)
|
|
_inject_tools(mgr, "srv_b", [{"name": "tool_beta", "description": "Beta tool",
|
|
"inputSchema": {"type": "object", "properties": {}}}])
|
|
mgr._generation += 1 # simulated successful connect
|
|
|
|
desc_b = mgr.get_tool_descriptions_for_prompt()
|
|
|
|
# Without the fix both describe tool_alpha (stale cache hit).
|
|
assert "tool_beta" in desc_b, (
|
|
"Cache was not invalidated: got stale description after reconnect"
|
|
)
|
|
assert "tool_alpha" not in desc_b
|