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https://github.com/langbot-app/LangBot.git
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feat(mcp): support mcp resources (#2215)
* feat(mcp): support mcp resources * feat(web): split MCP resources into tab * docs: add MCP resources PR review * feat(mcp): productionize resource support * feat(mcp): scope local agent tools and resources * fix(web): gate space embedding models behind login * fix(web): prevent clipped space model CTA * test: update preproc resource tool expectations * fix(web): expose skill authoring tools in selector --------- Co-authored-by: yang.xiang <yang.xiang@advancegroup.com> Co-authored-by: Hyu <chenhyu@proton.me> Co-authored-by: Junyan Qin <rockchinq@gmail.com>
This commit is contained in:
advancer-young
@@ -0,0 +1,278 @@
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from __future__ import annotations
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import base64
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from types import SimpleNamespace
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from unittest.mock import AsyncMock, Mock
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import pytest
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from mcp import types as mcp_types
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from langbot.pkg.provider.tools.loaders.mcp import (
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MCP_RESOURCE_CONTEXT_QUERY_KEY,
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MCP_RESOURCE_TRACE_QUERY_KEY,
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MCP_TOOL_LIST_RESOURCES,
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MCP_TOOL_READ_RESOURCE,
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MCPLoader,
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MCPSessionStatus,
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RuntimeMCPSession,
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)
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from langbot.pkg.telemetry import features as telemetry_features
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def _app() -> SimpleNamespace:
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return SimpleNamespace(logger=Mock())
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def _connected_session(
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*,
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name: str = 'docs',
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uuid: str = 'srv-1',
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resources: list[dict] | None = None,
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templates: list[dict] | None = None,
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) -> RuntimeMCPSession:
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session = RuntimeMCPSession(name, {'uuid': uuid, 'mode': 'remote'}, True, _app())
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session.status = MCPSessionStatus.CONNECTED
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session.session = SimpleNamespace(read_resource=AsyncMock())
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session.resources = resources or [
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{
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'uri': 'file:///README.md',
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'name': 'README.md',
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'title': '',
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'description': '',
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'mime_type': 'text/markdown',
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'size': None,
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'icons': [],
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'annotations': {},
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'_meta': {},
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}
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]
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session.resource_templates = templates or []
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return session
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def _query() -> SimpleNamespace:
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return SimpleNamespace(variables={})
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@pytest.mark.asyncio
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async def test_read_resource_envelope_truncates_caches_and_records_trace():
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session = _connected_session()
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session.session.read_resource.return_value = mcp_types.ReadResourceResult(
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contents=[
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mcp_types.TextResourceContents(
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uri='file:///README.md',
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mimeType='text/markdown',
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text='abcdef',
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)
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]
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)
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query = _query()
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first = await session.read_resource_envelope(
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'file:///README.md',
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max_bytes=4,
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source='ui_preview',
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query=query,
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)
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second = await session.read_resource_envelope(
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'file:///README.md',
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max_bytes=4,
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source='agent_tool',
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query=query,
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)
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assert first['contents'][0]['text'] == 'abcd'
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assert first['contents'][0]['bytes'] == 6
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assert first['truncated'] is True
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assert first['cache_hit'] is False
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assert second['cache_hit'] is True
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assert second['source'] == 'agent_tool'
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assert session.session.read_resource.await_count == 1
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traces = query.variables[MCP_RESOURCE_TRACE_QUERY_KEY]
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assert [trace['source'] for trace in traces] == ['ui_preview', 'agent_tool']
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assert traces[1]['cache_hit'] is True
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assert query.variables[telemetry_features.FEATURES_KEY]['mcp_resource_reads'] == {
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'ui_preview': 1,
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'agent_tool': 1,
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}
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@pytest.mark.asyncio
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async def test_read_resource_envelope_shares_byte_budget_across_text_contents():
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session = _connected_session()
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session.session.read_resource.return_value = mcp_types.ReadResourceResult(
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contents=[
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mcp_types.TextResourceContents(
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uri='file:///README.md#first',
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mimeType='text/plain',
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text='abc',
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),
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mcp_types.TextResourceContents(
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uri='file:///README.md#second',
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mimeType='text/plain',
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text='def',
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),
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]
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)
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envelope = await session.read_resource_envelope('file:///README.md', max_bytes=4)
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assert [item['text'] for item in envelope['contents']] == ['abc', 'd']
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assert envelope['contents'][0]['truncated'] is False
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assert envelope['contents'][1]['truncated'] is True
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assert envelope['bytes'] == 6
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assert envelope['truncated'] is True
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@pytest.mark.asyncio
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async def test_read_resource_envelope_omits_binary_by_default():
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session = _connected_session(
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resources=[
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{
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'uri': 'file:///image.png',
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'name': 'image.png',
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'title': '',
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'description': '',
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'mime_type': 'image/png',
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'size': 4,
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'icons': [],
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'annotations': {},
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'_meta': {},
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}
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]
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)
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session.session.read_resource.return_value = mcp_types.ReadResourceResult(
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contents=[
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mcp_types.BlobResourceContents(
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uri='file:///image.png',
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mimeType='image/png',
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blob=base64.b64encode(b'\x00\x01\x02\x03').decode(),
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)
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]
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)
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envelope = await session.read_resource_envelope('file:///image.png')
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content = envelope['contents'][0]
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assert content['type'] == 'blob'
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assert content['blob'] is None
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assert content['bytes'] == 4
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assert content['binary_omitted'] is True
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assert envelope['truncated'] is True
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assert envelope['warnings'] == ['Binary resource content omitted from response.']
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@pytest.mark.asyncio
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async def test_read_resource_envelope_rejects_unlisted_uri():
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session = _connected_session()
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with pytest.raises(ValueError, match='Resource URI is not available'):
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await session.read_resource_envelope('file:///secret.txt')
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session.session.read_resource.assert_not_called()
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def test_resource_uri_allowed_supports_listed_templates_conservatively():
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session = _connected_session(
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resources=[],
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templates=[
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{
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'uri_template': 'repo://{owner}/{repo}/file/{path}',
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'name': 'repository file',
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'title': '',
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'description': '',
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'mime_type': 'text/plain',
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'icons': [],
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'annotations': {},
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'_meta': {},
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}
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],
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)
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assert session.resource_uri_allowed('repo://langbot-app/LangBot/file/src/main.py') is True
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assert session.resource_uri_allowed('repo://langbot-app/LangBot/issues/1') is False
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assert session.resource_uri_allowed('https://example.com/secret') is False
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@pytest.mark.asyncio
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async def test_mcp_loader_can_hide_synthetic_resource_tools():
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loader = MCPLoader(_app())
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session = _connected_session()
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loader.sessions = {'docs': session}
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with_resource_tools = await loader.get_tools(['srv-1'], include_resource_tools=True)
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without_resource_tools = await loader.get_tools(['srv-1'], include_resource_tools=False)
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assert {tool.name for tool in with_resource_tools} == {
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MCP_TOOL_LIST_RESOURCES,
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MCP_TOOL_READ_RESOURCE,
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}
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assert without_resource_tools == []
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@pytest.mark.asyncio
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async def test_mcp_loader_refuses_resource_tool_calls_when_agent_read_disabled():
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loader = MCPLoader(_app())
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session = _connected_session()
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loader.sessions = {'docs': session}
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query = SimpleNamespace(
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variables={
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'_pipeline_bound_mcp_servers': ['srv-1'],
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'_pipeline_mcp_resource_agent_read_enabled': False,
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}
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)
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result = await loader.invoke_tool(
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MCP_TOOL_READ_RESOURCE,
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{'server_name': 'docs', 'uri': 'file:///README.md'},
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query,
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)
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assert result[0].text == 'Error: MCP resource agent reads are disabled.'
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session.session.read_resource.assert_not_called()
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@pytest.mark.asyncio
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async def test_build_resource_context_for_query_uses_only_bound_attached_text_resources():
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loader = MCPLoader(_app())
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docs = _connected_session(name='docs', uuid='srv-1')
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docs.session.read_resource.return_value = mcp_types.ReadResourceResult(
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contents=[
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mcp_types.TextResourceContents(
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uri='file:///README.md',
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mimeType='text/markdown',
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text='LangBot MCP resource context',
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)
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]
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)
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other = _connected_session(name='other', uuid='srv-2')
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other.session.read_resource.return_value = mcp_types.ReadResourceResult(
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contents=[
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mcp_types.TextResourceContents(
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uri='file:///README.md',
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mimeType='text/markdown',
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text='must not be injected',
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)
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]
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)
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loader.sessions = {'docs': docs, 'other': other}
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query = SimpleNamespace(
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variables={
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'_pipeline_bound_mcp_servers': ['srv-1'],
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'_pipeline_mcp_resource_attachments': [
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{'server_uuid': 'srv-1', 'server_name': 'docs', 'uri': 'file:///README.md', 'mode': 'pinned'},
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{'server_uuid': 'srv-2', 'server_name': 'other', 'uri': 'file:///README.md', 'mode': 'pinned'},
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],
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}
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)
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context = await loader.build_resource_context_for_query(query)
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assert '<mcp_resource ' in context
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assert 'server="docs"' in context
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assert 'LangBot MCP resource context' in context
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assert 'must not be injected' not in context
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assert query.variables[MCP_RESOURCE_CONTEXT_QUERY_KEY]['resource_count'] == 1
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docs.session.read_resource.assert_awaited_once()
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other.session.read_resource.assert_not_called()
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