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@alexander-alderman-webb alexander-alderman-webb commented Jan 12, 2026

Description

  • Patch StreamableHTTPServerTransport.handle_request() to store isolation and current scopes on the Starlette request object's scope attribute.

  • Run MCP handlers in the context of the stored scopes, if these are available.

  • Modify use_isolation_scope() and use_scope() context managers to accept None. The MCP protocol allows for transport layers that are not HTTP-based, so the scopes may not be available.

The Python MCP SDK uses an in-memory queue of requests. The HTTP propagation context is not active in the MCP decorators we patch, since they run after requests are retrieved from the queue.

Issues

Closes #5272
Closes PY-2022
Closes TET-1688

Reminders

@alexander-alderman-webb alexander-alderman-webb marked this pull request as ready for review January 12, 2026 14:43
@alexander-alderman-webb alexander-alderman-webb requested a review from a team as a code owner January 12, 2026 14:43
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github-actions bot commented Jan 13, 2026

Semver Impact of This PR

🟢 Patch (bug fixes)

📋 Changelog Preview

This is how your changes will appear in the changelog.
Entries from this PR are highlighted with a left border (blockquote style).


New Features ✨

Span Streaming

  • feat(span-streaming): Add spans to telemetry pipeline, add span name and attributes (3) by sentrivana in #5399
  • feat(span-streaming): Add span batcher (2) by sentrivana in #5398
  • feat(span-streaming): Add experimental trace_lifecycle switch (1) by sentrivana in #5397

Other

  • feat(integration): add gen_ai.conversation.id if available by constantinius in #5307

Bug Fixes 🐛

Google Genai

  • fix(google-genai): Token reporting by alexander-alderman-webb in #5404
  • fix(google-genai): deactivate google genai when langchain is used by shellmayr in #5389

Mcp

  • fix(mcp): Nest MCP spans under HTTP transactions by alexander-alderman-webb in #5292
  • fix(mcp): Handle all awaitable return types by alexander-alderman-webb in #5415

Span Streaming

  • fix(span-streaming): Always preserialize attributes by sentrivana in #5407
  • fix(span-streaming): Warn about thread usage if any batcher is active by sentrivana in #5408

Other

  • fix(anthropic): Token reporting by alexander-alderman-webb in #5403
  • fix(arq): handle settings_cls passed as keyword argument by nc9 in #5393
  • fix(dramatiq): cleanup isolated scope and transaction when message is skipped by frankie567 in #5346
  • fix(openai): Token reporting by alexander-alderman-webb in #5406
  • fix(openai-agents): Inject propagation headers for HostedMCPTool when streaming by alexander-alderman-webb in #5405
  • fix: Fix list attribute type by sentrivana in #5417
  • fix: Adapt to new packaging in toxgen by sentrivana in #5382

Internal Changes 🔧

Fastmcp

  • test(fastmcp): Wrap prompt in Message by alexander-alderman-webb in #5411
  • test(fastmcp): Remove test_fastmcp_without_request_context() by alexander-alderman-webb in #5412
  • test(fastmcp): Use AsyncClient for SSE by alexander-alderman-webb in #5400
  • test(fastmcp): Use TestClient for Streamable HTTP by alexander-alderman-webb in #5384
  • test(fastmcp): Simulate stdio transport with memory streams by alexander-alderman-webb in #5333

Mcp

  • test(mcp): Use AsyncClient for SSE by alexander-alderman-webb in #5396
  • test(mcp): Use TestClient for Streamable HTTP by alexander-alderman-webb in #5383
  • test(mcp): Remove unused stdio helpers by alexander-alderman-webb in #5409
  • test(mcp): Simulate stdio transport with memory streams by alexander-alderman-webb in #5329

Other

  • ci: Fix lint step by sentrivana in #5418
  • ci: 🤖 Update test matrix with new releases (02/02) by github-actions in #5413
  • ci: Update tox and pin packaging version for tox by alexander-alderman-webb in #5381
  • ci: migration to the new codecov action by MathurAditya724 in #5392

Other


🤖 This preview updates automatically when you update the PR.

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See comments, but other than that LGTM!

@alexander-alderman-webb alexander-alderman-webb marked this pull request as draft January 16, 2026 14:37
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github-actions bot commented Feb 4, 2026

Codecov Results 📊

13 passed | Total: 13 | Pass Rate: 100% | Execution Time: 7.35s

All tests are passing successfully.

❌ Patch coverage is 1.82%. Project has 13629 uncovered lines.

Files with missing lines (180)
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@alexander-alderman-webb alexander-alderman-webb marked this pull request as ready for review February 4, 2026 14:01
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@alexander-alderman-webb alexander-alderman-webb merged commit 3bb163a into master Feb 4, 2026
154 checks passed
@alexander-alderman-webb alexander-alderman-webb deleted the webb/mcp-in-http branch February 4, 2026 14:42
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MCP tool calls break distributed tracing within same service

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