How do you merge or compose multiple LoRA adapters, and when does it break?
Merging one adapter is a single matrix add. Merging four is where careers get interesting: the low-rank updates were each trained as if the others did not exist, and they collide. Here is what actually works and when to route instead.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Merging one adapter is a single matrix add. Merging four is where careers get interesting: the low-rank updates were each trained as if the others did not exist, and they collide. Here is what actually works and when to route instead.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
