CI: revert smoke-test '| cat > file' workaround when .NET 11 preview 4 SDK ships

[richlander]

Context

CI smoke tests in .github/workflows/ci.yml were temporarily changed from

dotnet-inspect ... > smoke.md

to

dotnet-inspect ... | cat > smoke.md

(see commits in PR #317 and PR #312) to work around a .NET 11 preview 3 SDK regression.

Root cause (upstream)

dotnet/runtime#125512 routed ConsolePal.Unix.Write through RandomAccess.Write(fd, buffer, fileOffset: 0). On a seekable fd (regular file opened by shell > redirection), that becomes pwrite(fd, buffer, 0) on every call — so each Console.WriteLine overwrites from byte 0 of the file. On a pipe (e.g. | cat) the runtime falls back to write(2) and the output is correct.

Symptom for dotnet-inspect: cmd > file.md produced ~256 bytes of fragmented mid-line content (the truncated tail of whatever the last buffer flush wrote); cmd | cat > file.md produced the full ~2 KB of valid markdown.

Local repro (50 line program, 3750 bytes total):

SDK	> file	| cat > file
11.0.100-preview.1.26104.118	3750	3750
11.0.100-preview.2.26159.112	3750	3750
11.0.100-preview.3.26207.106	75	3750

(75 bytes = exactly the last Console.WriteLine.)

Already fixed upstream

dotnet/runtime#126844 (issue #126843, merged 2026-04-20) reverts the RandomAccess.Write switch back to the original Interop.Sys.Write loop.

The fix did not make the preview 3 cut, so GitHub-hosted runners are still on the broken SDK.

Action

When .NET 11 preview 4 ships (expected 2026-05-12, Patch Tuesday) and the GitHub Actions runner image picks it up:

• Verify a fresh CI run on main works with cmd > file (revert workaround locally and try)
• Remove | cat from the six smoke tests in .github/workflows/ci.yml (steps "Smoke test - package quiet/normal/...", "type/member command (oneline/markdown)") and the explanatory comment above the first one
• Close this issue