Fix local nbextensions path resolution for kernels launched from local kernelspec

[Copilot]

This PR fixes an issue where local nbextensions could not be found when kernels were launched from local kernelspecs, even when those kernelspecs had an associated Python interpreter with nbextensions installed.

Problem

The NbExtensionsPathProvider was missing a case for handling 'startUsingLocalKernelSpec' kernel connections. This caused the provider to always return undefined for local kernelspec-based kernels, resulting in the error message "No nbextensions folder found for kernel" and preventing widgets from working when CDN access was unavailable.

Root Cause

The switch statement in NbExtensionsPathProvider.node.ts only handled:

• 'startUsingPythonInterpreter' → returns sysPrefix/share/jupyter
• 'connectToLiveRemoteKernel' and 'startUsingRemoteKernelSpec' → returns baseUrl
• default → returns undefined

Local kernelspecs ('startUsingLocalKernelSpec') fell through to the default case and always returned undefined, even when they had an associated Python interpreter.

Solution

Added a new case for 'startUsingLocalKernelSpec' that:

1. Checks if the kernelspec has an associated Python interpreter
2. If yes, uses the same logic as 'startUsingPythonInterpreter' to return sysPrefix/share/jupyter
3. If no interpreter, returns undefined (maintaining existing behavior for non-Python kernels)

Testing

• Added comprehensive test coverage for the new case
• Verified all existing tests continue to pass
• Confirmed the fix works for both Node.js and Web environments appropriately

This change is minimal, safe, and maintains backward compatibility while fixing the specific scenario described in the issue.

Fixes #16823.

Warning

Firewall rules blocked me from connecting to one or more addresses

I tried to connect to the following addresses, but was blocked by firewall rules:

• 0.0.0.123
  • Triggering command: node /home/REDACTED/work/vscode-jupyter/vscode-jupyter/node_modules/.bin/mocha --config ./build/.mocha.unittests.js.json ./out/interactive-window/generatedCodeStorageManager.unit.test.js ./out/interactive-window/shiftEnterBanner.unit.test.js ./out/kernels/helpers.unit.test.js ./out/kernels/kernelAutoReConnectMonitor.unit.test.js ./out/kernels/kernelAutoRestartMonitor.unit.test.js ./out/kernels/kernelCrashMonitor.unit.test.js ./out/kernels/kernelDependencyService.unit.test.js ./out/kernels/kernelFinder.unit.test.js ./out/kernels/kernelProvider.node.unit.test.js ./out/kernels/kernelProvider.web.unit.test.js ./out/kernels/kernelRefreshIndicator.node.unit.test.js ./out/kernels/kernelRefreshIndicator.web.unit.test.js ./out/test/package.nls.json.unit.test.js out/**/ipyWidgetScriptSourceProvider.unit.test.js (packet block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
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[DonJayamanne]

@copilot there are some formatting errors, run npm run format-fix and commit the changes

[Copilot]

@copilot there are some formatting errors, run npm run format-fix and commit the changes

Fixed formatting errors with npm run format-fix. The trailing whitespace in the comment has been removed. (02d065c)