Engine interface
The adapter contract every generation engine implements.
Each engine exports key, label, isReady(), and generate({ characterPhotoPaths, posePhotoPath, prompt, outputPath, outputSettings, apiKey, model }). isReady() returns { ready, reason? }; generate must write an image to outputPath or throw a clear Error. outputSettings and model are optional and adapters must provide safe defaults.
characterPhotoPaths is an array of 1-4 local file paths (one per person in the generation, in order — this is also the order the prompt text refers to them by, e.g. "Image 1", "Image 2"). Every path must be included in the request to the underlying model; dropping any of them means that person won't appear in the output. prompt (built by lib/promptTemplate.js) already accounts for however many paths were given, so adapters don't need to reason about the count themselves — just forward every image, in order, followed by the pose reference.