ChatThreadRecentItemSerializer_V2

Represents a single recent chat thread in the flat chronological list.

thread_id + agent_id → frontend builds nav URL: /agents/{agent_id}/chat/{thread_id}

agent_name → shown as a label on each thread item in the sidebar

agent_image → agent avatar/image URL with SAS token appended (1 hour expiry)

last_active → frontend uses this to group threads into Today / Yesterday / Last 7 Days / Older

{
    "thread_id": 0,
    "thread_title": "string",
    "agent_id": 0,
    "agent_name": "string",
    "agent_image": "string",
    "last_active": "2019-08-24T14:15:22.123Z"
}