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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

Comment on lines 1874 to 1902
def use_isolation_scope(isolation_scope: "Scope") -> "Generator[Scope, None, None]":
def use_isolation_scope(isolation_scope: "S") -> "Generator[S, None, None]":
"""
.. versionadded:: 2.0.0
Context manager that uses the given `isolation_scope` and runs the wrapped code in it.
The current scope is also forked to not bleed data into the existing current scope.
After the wrapped code is executed, the original scopes are restored.
Example Usage:
.. code-block:: python
import sentry_sdk
with sentry_sdk.isolation_scope() as scope:
scope.set_tag("color", "green")
sentry_sdk.capture_message("hello") # will include `color` tag.
sentry_sdk.capture_message("hello, again") # will NOT include `color` tag.
"""
if isolation_scope is None:
yield isolation_scope
return
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@alexander-alderman-webb alexander-alderman-webb Jan 12, 2026

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I'm not sure about accepting None in the context managers. It's convenient in the MCP integration since it helps avoid code duplication (or the need to break stuff into more functions).

We could also just check if the scopes are None, so I can adjust if needed.

@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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MCP tool calls break distributed tracing within same service

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