David decided: Separated assignment planner from lecture notes pipeline with a feature flag

David asked Codex to disable assignment planner candidates without making the system state messy or hard to reverse.

i dont want assignent planner AI calls (or the assignment planner fallbacks) to be running, not for now. ie. i dont want assignment candidates being producted or assignment plans being produced. we should just do soemthign to stop this from happening in a way that makes it super easy to turn them back on and have assignment planners work again later when we want them back.

When the agent proposed an env-flag approach (ASSIGNMENT_PLANNER_ENABLED=false), David immediately asked whether it would bleed into module planners or lecture notes — confirming the decision required surgical isolation. The investigation confirmed the flag was safe and scoped only to assignment planning.