BYOK models with toolCalling=false still appear in Ask mode model picker

Problem

Currently in Eclipse Copilot, when a user adds a custom BYOK model with Support Tool Calling unchecked (i.e. oolCalling=false), the model still appears in the model picker under Ask mode.

In VS Code, such models do not appear in the model picker under any mode (including Ask), because Ask mode now also supports and relies on tool calling.

Current Behavior (Eclipse)

• toolCalling=false BYOK model → has CHAT_PANEL scope only (no AGENT_PANEL)
• Ask mode maps to chat-panel scope → model appears in Ask model picker
• Agent/Plan mode maps to agent-panel scope → model does not appear

Expected Behavior

Since Ask mode now also uses tool calling, a BYOK model with toolCalling=false should arguably not appear in any mode's model picker — matching VS Code's behavior.

Key Code Paths

• ModelUtils.java (com.microsoft.copilot.eclipse.ui.utils): assigns CHAT_PANEL scope to all BYOK models, and only adds AGENT_PANEL when toolCalling=true
• ModelService.java: filters models by scope based on current chat mode (Ask → chat-panel, Agent → agent-panel)
• AddByokModelDialog.java: builds the BYOK model with capabilities from user input

Discussion Points

• Should we filter out toolCalling=false BYOK models from all modes (including Ask)?
• Or should we keep them visible in Ask but clearly indicate they have limited capability?
• Need to align with VS Code's latest behavior for consistency across editors.

Start with ModelUtils.java, ModelService.java, and AddByokModelDialog.java to trace BYOK capabilities and scope filtering for Ask, Agent, and Plan modes. Compare the current Eclipse behavior with the VS Code behavior described in the issue, then confirm the chosen visibility rule and verify that the model picker reflects it consistently.