fix: prevent _auth_ metadata from leaking to upstream MCP servers#325
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fix: prevent _auth_ metadata from leaking to upstream MCP servers#325
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injectAuthMetadata() was mutating the args map in-place, causing _auth_* fields to be forwarded to upstream servers via CallTool(). FastMCP-based servers using Pydantic's validate_call reject unknown keyword arguments, breaking tool calls for authenticated users. Fix: injectAuthMetadata() now returns a shallow copy. All call sites use separate activityArgs for logging and clean args for upstream forwarding. Closes #322 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
injectAuthMetadata()was mutating theargsmap in-place, causing_auth_*fields (auth_type, agent_name, token_prefix) to be forwarded to upstream MCP servers viaCallTool()validate_callreject unknown keyword arguments, breaking all tool calls for authenticated usersinjectAuthMetadata()now returns a shallow copy; all 3 call sites use separateactivityArgsfor logging and cleanargsfor upstream forwardingTestInjectAuthMetadata_DoesNotMutateOriginalto prevent regressionCloses #322
Test plan
TestInjectAuthMetadata_*/TestGetAuthMetadata_*tests passinternal/...test suite passes (only pre-existing e2e timeout unrelated to change)🤖 Generated with Claude Code