Whenever I use a frontier model or any model for plan mode, and then try using mutlitask or click build in paralel with composer 2.5 fast selected, it keeps using the model of the original plan mode.
Steps to Reproduce
Plan using different model, usually frontier models
After plan is done, below the markdown.md, there is a model selection option, choose composer 2.5. THen click build in Parallel.
Keep the chat model at the bottom as is, it would usually be the orginal frontier model uses for plan mode.
See the models that are chosen using frontier models.
Expected Behavior
The models that subagents choose should be the one I chose below the plan markdown option instead of the original frontier model.
Thanks for the report, @ZoellaB! This is a known issue that we’re currently tracking.
As a workaround: parallel/multitask children currently always inherit the model used in the chat, so you can set the main chat model to Composer 2.5 before clicking Build in Parallel, and the correct model should be used.
I experienced this yesterday. Using /multi-task, auto, I assigned the agent the task of acting as an orchestrator and parallel-developing 3 phases of my application. I noticed Sonnet 5 Medium was chosen for a number of the tasks. I was surprised to see a 10% use of API in my costs page given I ran it under auto mode.
The main session was on grok-4.5 and for some reason a gpt-5.5-xhigh was selected for multitasking and this took a nice chunky 10% bite out of my API usage. Luckily i was on 20% only, but such behavior makes multitasking a risky endeavour.
Best we can do right now is to change the model at the bottom to the model you want it to use for multi-task. It’s unfortunate the UI/UX isn’t following how it is supposed to be.