Let Compact continue on another model or vendor

internal/agents/leadtools.go

@@ -325,13 +325,24 @@ func (m *Manager) leadTools(l *live) []mcp.Tool {
 				return "Interrupted.", nil
 			}),
 
-		tool("compact_task", "Have a task's idle agent write a handoff and continue in a fresh session.", taskOnly,
+		tool("compact_task", "Have a task's idle agent write a handoff and continue in a fresh session.",
+			`{"type": "object", "properties": {
+				"task_id": {"type": "string"},
+				"model": {"type": "string", "description": "Start the fresh session on this model, on either vendor; the current agent still writes the handoff. Defaults to the current model."}
+			}, "required": ["task_id"]}`,
 			func(ctx context.Context, user api.User, raw json.RawMessage) (string, error) {
+				args := struct {
+					Model string `json:"model"`
+				}{}
+				err := json.Unmarshal(raw, &args)
+				if err != nil {
+					return "", err
+				}
 				sess, err := m.taskSessionArg(ctx, raw)
 				if err != nil {
 					return "", err
 				}
-				_, err = m.Compact(ctx, sess.Id)
+				_, err = m.Compact(ctx, sess.Id, args.Model)
 				if err != nil {
 					return "", err
 				}