[rudycelekli]

Problem

IsolationManager.DetectRuntimeType switches on filepath.Base(command) exactly. On Windows the launchers carry an executable suffix: uvx.exe, npx.cmd, npm.cmd, yarn.cmd, pip.exe, go.exe. Configs often name them that way, either by full path or because npx.cmd is what resolves. None of those match a case, so they fall to the binary default. python.exe and node.exe only work through the substring fallback.

With Docker isolation enabled, binary selects the generic image, and TransformCommandForContainer passes the original command through. The container is asked to run npx.cmd (or uvx.exe) inside a Linux image where it doesn't exist, so the server never starts.

Fix

Lowercase the base name and strip a .exe, .cmd or .bat suffix before the switch, so npx.cmd maps to npx, uvx.exe to uvx, and so on. Then the right image and in-container command are used. Unsuffixed names are unchanged.

Test

TestDetectRuntimeType_WindowsExecutableSuffix covers uvx.exe, npx.cmd, NPX.CMD, npm.cmd, yarn.cmd, pip.exe and go.exe, plus uvx and an unknown my-tool. On main all seven suffixed names return binary; with this change they map to their runtime. go test -count=1 ./internal/upstream/core/ passes.

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[codecov-commenter]

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Codecov Report

❌ Patch coverage is 83.33333% with 2 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
internal/diagnostics/remediation.go	75.00%	0 Missing and 2 partials ⚠️

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[Dumbris]

Verified the bug on main and the fix; thank you! The review found one gap, so I pushed a small maintainer commit on top of your branch: internal/diagnostics.detectDockerRuntimeType is documented as a mirror of DetectRuntimeType; the commit applies the same suffix stripping there, so remediation hints for uvx.exe match what spawn actually does.

I will merge once CI is green.

[Dumbris]

Verified: the bug reproduces on main and the PR fixes it. The review found one gap, closed by the maintainer commit on top (regression test included). Race tests and CI lint for the touched packages are clean on this branch merged with main, and the result was cross-reviewed clean.

[Dumbris]

Merged. Thank you, @rudycelekli! Windows launchers like uvx.exe and npx.cmd now get the right runtime detection (and the matching isolation image) instead of falling through to a plain binary, and diagnostics stay in step with it.

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