Fix model picker to handle metadata.id collisions between vendors

[vritant24]

No description provided.

[Copilot]

Pull request overview

This PR updates the chat model picker collision handling so models from different vendors that share the same metadata.id are not hidden from the grouped picker.

Changes:

• Separates placement tracking for globally unique model identifiers vs control-manifest ids.
• Preserves the first metadata-id lookup entry for legacy/id-based resolution.
• Adds regression tests for BYOK/Copilot metadata-id collisions.

Show a summary per file

File	Description
src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts	Adjusts grouped picker placement and Other Models filtering for metadata-id collisions.
src/vs/workbench/contrib/chat/test/browser/widget/input/chatModelPicker.test.ts	Adds regression coverage for BYOK models sharing metadata ids with Copilot models.

Copilot's findings

Comments suppressed due to low confidence (2)

src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts:623

• Surfacing colliding BYOK models in Other Models is incomplete because the rendering path below still looks up controlModels[model.metadata.id]. A Copilot control entry with a minVSCodeVersion for this id will disable the BYOK model as unavailable even though that manifest entry only describes copilot/<id>; Other Models should avoid applying Copilot-only control entries to non-Copilot models with the same metadata id.

			// Filter only by identifier — metadata.id is not unique across
			// vendors, so a BYOK model with the same metadata.id as an
			// already-placed Copilot model must still be surfaced here.
			otherModels = models.filter(m => !placedIdentifiers.has(m.identifier));

src/vs/workbench/contrib/chat/browser/widget/input/chatModelPicker.ts:533

• This promoted-model path still applies controlModels[model.metadata.id] after resolving by a full model identifier. If the selected or recent model is a BYOK model whose metadata id collides with a Copilot entry, the Copilot entry's version gate/unavailable metadata can disable or relabel the BYOK model; only apply metadata-id control entries to the Copilot model they describe.

				if (model && !placedIdentifiers.has(model.identifier)) {
					markModelPlaced(model);
					const entry = controlModels[model.metadata.id];

• Files reviewed: 2/2 changed files
• Comments generated: 2