debt - cleanup from sidebar support in modal editors

[bpasero]

Removes leftover modal-editor sidebar/min-width configurability plumbing and centralizes "changes list" rendering/styling so the same list can be used in the modal editor sidebar.

Changes Made

• Removed workbench.editor.modalMinWidth configuration and simplified modal min-width handling.
• Refactored ChangesViewPane to reuse a shared createChangesTree helper for both the main Changes view and the modal sidebar list; adjusted CSS scoping accordingly.
• Parameterized createChangesTree with an optional getSelection callback so the ChangesViewActionRunner for the sidebar tree reads from the sidebar tree's own selection instead of the main view's selection.
• Added a new unit test suite to validate modal sidebar behaviors.
• Fixed JSDoc comment on IModalEditorPartOptions.sidebar to accurately describe that the sidebar cannot be added, removed, or updated after the modal editor is opened.

Testing

• TypeScript compilation passes with no errors.
• Verify that row toolbar actions in the sidebar list operate on the sidebar tree's selection rather than the main Changes view's selection.

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[Copilot]

Pull request overview

Removes leftover modal-editor sidebar/min-width configurability plumbing and centralizes “changes list” rendering/styling so the same list can be used in the modal editor sidebar.

Changes:

• Removed workbench.editor.modalMinWidth configuration and simplified modal min-width handling.
• Refactored ChangesViewPane to reuse a shared tree-creation helper for both the main Changes view and the modal sidebar list; adjusted CSS scoping accordingly.
• Added a new unit test suite intended to validate modal sidebar behaviors.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/vs/workbench/test/browser/parts/editor/modalEditorSidebar.test.ts	Adds a new test harness + tests for modal sidebar width/content behaviors.
src/vs/workbench/browser/workbench.contribution.ts	Removes the workbench.editor.modalMinWidth setting contribution.
src/vs/workbench/browser/parts/editor/modalEditorPart.ts	Simplifies effective min-width calculation and removes sidebar dynamic update wiring.
src/vs/workbench/browser/parts/editor/media/modalEditorPart.css	Removes modal-editor sidebar styling that was specific to changes-list badges/stats.
src/vs/sessions/contrib/configuration/browser/configuration.contribution.ts	Removes sessions default override for workbench.editor.modalMinWidth.
src/vs/sessions/contrib/changes/browser/media/changesView.css	Broadens selectors to style .chat-editing-session-list outside .changes-view-body.
src/vs/sessions/contrib/changes/browser/changesView.ts	Extracts createChangesTree and reuses it for the modal editor sidebar list.
src/vs/platform/editor/common/editor.ts	Updates sidebar option documentation to reflect reduced dynamic behavior.

Comments suppressed due to low confidence (2)

src/vs/sessions/contrib/changes/browser/changesView.ts:1258

• createChangesTree hard-codes the tree id as 'ChangesViewTree'. This method is now used to create both the main Changes tree and the modal editor sidebar tree, so the ids will collide if both exist (state/telemetry/context can become ambiguous). Consider accepting the id as a parameter (e.g. 'ChangesViewTree' vs 'ModalEditorSidebar').

		return disposables.add(this.instantiationService.createInstance(
			WorkbenchCompressibleObjectTree<ChangesTreeElement>,
			'ChangesViewTree',
			container,

src/vs/sessions/contrib/changes/browser/changesView.ts:1266

• createChangesTree uses a widget aria label of “Changes Tree” for all instances. This regresses the modal sidebar list accessibility label (previously “Files”). Consider parameterizing the aria label (and related sidebar-specific options like multipleSelectionSupport, compressionEnabled, and dnd) so the sidebar tree can keep an appropriate, context-specific label.

				accessibilityProvider: {
					getAriaLabel: (element: ChangesTreeElement) => isChangesFileItem(element) ? basename(element.uri.path) : element.name,
					getWidgetAriaLabel: () => localize('changesViewTree', "Changes Tree")
				},