Implement session state tracking for "Run and Debug" button when Inte…

[Prashant Kumar Rai (8prashant)]

Fixes #13001

When C_Cpp.intelliSenseEngine is set to "disabled", the language server client is not started. Previously, cpptools.buildAndDebug.isSourceFile and cpptools.buildAndDebug.isFolderOpen context keys (which control the visibility of the "Run / Debug C/C++ File" and "Add Debug Configuration" editor action buttons) were only updated within the language server client (client.ts). Consequently, disabling IntelliSense would cause the Run/Debug shortcut buttons to never appear in the editor title bar.

This PR updates the Debugger extension initialization (Debugger/extension.ts) to track active text editor changes and keep buildAndDebugIsSourceFile and buildAndDebugIsFolderOpen up to date regardless of whether IntelliSense is enabled or disabled.

Changes

1. Added updateBuildAndDebugSessionState and registered an onDidChangeActiveTextEditor listener in DebuggerExtension.initialize.
2. Added unit tests in Extension/test/scenarios/SingleRootProject/tests/buildAndDebug.test.ts verifying session state updates for source files, header files, non-C/C++ files, and undefined editors.

Verification

• Compiled with TypeScript (yarn compile) with 0 errors.
• Ran tests via yarn test --scenario=SingleRootProject and verified all BuildAndDebug SessionState Tests pass.

[Copilot]

Pull request overview

Ensures Run/Debug editor actions remain available when IntelliSense is disabled.

Changes:

• Tracks active editor changes in the debugger extension.
• Updates build/debug session context keys.
• Adds source, header, non-C/C++, and undefined-editor tests.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
Extension/src/Debugger/extension.ts	Adds independent session-state tracking.
Extension/test/scenarios/SingleRootProject/tests/buildAndDebug.test.ts	Tests source-file state updates.

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[Sean McManus (sean-mcmanus)]

Found one session-state lifecycle gap that should be addressed before merging.

[Sean McManus (sean-mcmanus)]

✨Copilot (agent146): [Moderate] Please keep the folder context key current on every transition that can change isFolderOpen. This listener recomputes it only when the active editor is C/C++, and there is no debugger-side onDidChangeWorkspaceFolders listener. With IntelliSense disabled, opening an in-workspace C++ file sets the key to true; switching to a non-C/C++ editor leaves it true, so the editor context menu still offers C_Cpp.AddDebugConfiguration because that contribution checks only cpptools.buildAndDebug.isFolderOpen. Likewise, adding or removing the active file's workspace folder leaves the key stale until another editor change. Clear/recompute this key for non-C++/undefined editors and recompute it when workspace folders change; the tests should assert the folder key for those transitions as well.