chat: sort custom modes alphabetically by name in ChatModes

[sundeep8967]

Problem

In multi-root workspaces and dynamic customization updates, custom chat modes retrieved via ChatModes.getCustomModes() can be enumerated in non-deterministic order or insertion order depending on dictionary/map iteration and asynchronous resolution timing.

Solution

Sort custom mode instances in ChatModes.getCustomModes() deterministically by name (using localeCompare) and tie-break by ID/URI.

Fixes #332339

Testing

• Added unit test in src/vs/workbench/contrib/chat/test/common/chatModeService.test.ts verifying that custom modes are returned sorted alphabetically by name.
• TypeScript compiler verification passed.

[Copilot]

Pull request overview

Sorts custom chat modes alphabetically for stable Agent dropdown ordering.

Changes:

• Sorts by name, then URI-backed ID.
• Adds unit coverage for unsorted input.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
chatModes.ts	Sorts custom modes deterministically.
chatModeService.test.ts	Tests alphabetical ordering.

Suppressed comments (1)

src/vs/workbench/contrib/chat/test/common/chatModeService.test.ts:389

• The test guidance asks tests to minimize fine-grained assertions and prefer one snapshot-style deep equality assertion. Mapping the names into one array also gives a clearer failure diff and removes the redundant length assertion.

		assert.strictEqual(modes.custom.length, 3);
		assert.strictEqual(modes.custom[0].name.get(), 'Alpha Mode');
		assert.strictEqual(modes.custom[1].name.get(), 'Beta Mode');
		assert.strictEqual(modes.custom[2].name.get(), 'Zeta Mode');

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[sundeep8967]

@microsoft-github-policy-service agree