Intent of copilotAgent.ts ×3

All 3 exact tests in this concept. Every test is marked by where it enters the hierarchy.

mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/ 3 tests
- platform/ 3 tests
  - agentHost/ 3 tests
    
    test/ 3 tests
    
    node/ 3 tests
    
    copilotAgent.test|title=CopilotAgent peer chat create / 2 tests
    
    fork / 2 tests
    
    model+agent / 2 tests
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent peer chat create / fork / model+agent / restore round-trip createChat side chat forks hidden context and filters inherited turns|occurrence=1 Inherited restore round-trip createChat side chat forks hidden context and filters inherited turns|occurrence=1
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent peer chat create / fork / model+agent / restore round-trip createChat side chat preserves a local source turn id while forking from the concrete provider anchor|occurrence=1 Inherited copilotAgent.ts ×4
    
    mocha:v1|namespace=vscode@05c208e9e28d8c1c723fa08f85e2b7a96092e8e5|file=vs/platform/agentHost/test/node/copilotAgent.test|title=CopilotAgent chat surface (IAgentChats) getMessages returns the peer chat history|occurrence=1 Inherited agentPeerChats.ts ×1