Function seed_launch 

pub(crate) fn seed_launch(
    provider_id: &str,
    base: Vec<String>,
    provider_flags: &str,
) -> SeededLaunch

Build cmd:args and agent:runtime for a freshly opened pane.

base is the catalog argv for the pane’s controller. provider_flags is the agent definition’s own flags: they are appended last, exactly as the frontend does, and a --model / --effort among them is the agent’s own choice — it becomes the runtime the menu shows and no second flag is added, so the two cannot disagree.