Stabilize Fusion execution-timeout test against cold-start flake

[glen-84]

Summary

• CancellationTests.Request_Is_Running_Into_Execution_Timeout_While_Http_Request_In_Node_Is_Still_Ongoing flaked under CI load: the snapshot dropped the sourceSchemas[].interactions: block whenever the 250ms execution timeout elapsed before the gateway dispatched to the subgraph.
• Root cause: TimeoutMiddleware sits above parsing, planning, and execution in the pipeline, so first-request cold start (planning plus JIT, inside the timed window) can consume the 250ms before onBeforeSend records the subgraph request, leaving no interaction to snapshot.
• Fix: warm the gateway with a { __typename } request first. It resolves on the gateway, never reaches the subgraph, and records no interaction, so the executor build and pipeline JIT happen outside the tight timeout. The measured request then reliably records the interaction. The 250ms timeout and the committed snapshot are unchanged.

Test plan

• Ran the full CancellationTests class (both methods across net8.0, net9.0, and net10.0): all pass.
• Ran the previously-failing test 5 times on net10.0: consistently green.

[Copilot]

Pull request overview

Stabilizes a flaky Fusion execution-timeout snapshot test by warming up the gateway before running the time-budgeted request, reducing first-request cold-start/JIT overhead impact on the measured timeout window.

Changes:

• Adds a preliminary { __typename } request to warm the gateway before the 250ms execution-timeout scenario is exercised.

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[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall coverage in the gai/deflake-fusion-e... branch remains at 49%, unchanged from the main branch.

Show a code coverage summary of the most impacted files.

File	main eeb6a28	gai/deflake-fusion-e... 5d5b055	+/-
/home/runner/wo...erMiddleware.cs	100%	89%	-11%
/home/runner/wo...gerMessage.g.cs	15%	11%	-4%
/home/runner/wo...boxProcessor.cs	74%	72%	-2%
/home/runner/wo...ationPlanner.cs	88%	88%	0%
/home/runner/wo...geDispatcher.cs	72%	75%	+3%
/home/runner/wo...gerMessage.g.cs	6%	10%	+4%
/home/runner/wo...entsListener.cs	62%	66%	+4%
/home/runner/wo...gerMessage.g.cs	18%	23%	+5%
/home/runner/wo...heMiddleware.cs	86%	92%	+6%
/home/runner/wo...eiveEndpoint.cs	68%	77%	+9%

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_{Updated June 17, 2026 13:19 UTC
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