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fix(tools/list): initialize the server mode before choosing which tools to list - #482
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echarles merged 2 commits intoOct 5, 2026
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…ls to list get_registered_tools() read ServerContext._mode, which is None until initialize() runs. On a freshly started Jupyter extension, REST GET /mcp/tools/list was answered as if in MCP_SERVER mode and listed connect_to_jupyter, until a JSON-RPC request initialized the context. Read the .mode property instead, which initializes on first use. Fixes datalayer#481 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
echarles
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Oct 5, 2026
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Fixes #481.
get_registered_tools()readServerContext._mode, which staysNoneuntilinitialize()runs. On a freshly started Jupyter extension, the first RESTGET /mcp/tools/listtherefore took theMCP_SERVERbranch and listedconnect_to_jupyter. That lasted until a JSON-RPC request on/mcpinitialized the context. The fix reads the.modeproperty instead, which initializes on first use.This is one line in
server.py. The JSON-RPC handler'scontext.initialize(); mode = context._modealready behaves correctly, so I left it alone.Testing
tests/test_registered_tools_initializes_mode.py: starts from an uninitializedServerContextinside a stubbed local-document extension, and checks thatget_registered_tools()resolvesJUPYTER_SERVERmode and leaves outconnect_to_jupyter. It fails onmain(assert None == ServerMode.JUPYTER_SERVER) and passes with the fix.test_allowed_jupyter_mcp_tools.pyandtest_capabilities.pystill pass (42 passed with the new test).document_url=local,code_sandbox_url=local): the firstGET /mcp/tools/listnow returns 21 tools withoutconnect_to_jupyter. Before the fix it returned 22.🤖 Generated with Claude Code