Fix C# listFiles E2E ordering assumption

[stephentoub]

The C# and Rust E2E tests assumed workspaces.listFiles returns files in sorted or stable order, but the runtime does not guarantee workspace file enumeration order. That made the tests flaky when created files came back in a different filesystem/RPC order.

This updates both tests to assert the supported behavior instead: each listFiles call includes all files created by the test without asserting the returned order. The assertions compare the filtered results after ordinal sorting in C# and use presence checks for each Rust call.

Validation:

• dotnet test dotnet\test\GitHub.Copilot.SDK.Test.csproj --filter "FullyQualifiedName~Workspaces_CreateFile_Then_ListFiles_Returns_All_Files" --logger "console;verbosity=minimal"
• cargo +nightly-2026-04-14 fmt --check && cargo test --features test-support --test e2e workspaces_createfile_then_listfiles_returns_all_files -- --nocapture

[Copilot]

Pull request overview

This PR fixes a flaky .NET E2E test that incorrectly assumed workspaces.listFiles returns files in a stable/sorted order. The test now validates the supported contract: all created files are present, without asserting enumeration order.

Changes:

• Renamed the E2E test to reflect the intended assertion (all files returned, not order).
• Updated assertions to compare results after ordinal sorting, avoiding filesystem/RPC enumeration-order dependence.
• Updated comments to document that ordering is not guaranteed and to clarify the repeated-call expectation.

Show a summary per file

File	Description
dotnet/test/E2E/RpcAdditionalEdgeCasesE2ETests.cs	Makes the ListFiles E2E test order-independent by sorting filtered results before asserting equality.

Copilot's findings

• Files reviewed: 1/1 changed files
• Comments generated: 0

[github-actions]

Cross-SDK Consistency Review ✅

This PR fixes both the .NET and Rust E2E tests consistently — the same ordering assumption was present in both, and both are corrected in parallel with equivalent logic. The fix pattern is symmetric:

SDK	Before	After
.NET	Assert.Equal(paths, matchingFiles) (sorted assumption)	Assert.Equal(paths, matchingFiles.OrderBy(...))
Rust	assert_eq!(first.files, second.files) (stable assumption)	assert!(files.iter().any(...)) for each file

The other SDKs do not have this specific "sorted or stable order" assertion — their listFiles tests already use order-independent checks (toContain in Node.js, in in Python, containsString in Go), so no changes are needed there.

No cross-SDK consistency issues found.

Generated by SDK Consistency Review Agent for issue #1261 · ● 342.2K · ◷