The gallery picker

What the person sees. The gallery picker: the screen the feed's create button opens in the POST mode.

What you do. PostingGalleryPickerScreen is that screen: the person's photos and videos in a grid, under the mode selector. This page's mode is the post mode. This is the POST mode's gallery; STORY and REEL open the creation camera (camera). Opening the screen sends no request of its own.

Actions:

• pickPhoto(photo) — one photo; opens the post editor (post).
• pickPhotos(photos) — several photos, the grid's Select mode: a carousel. The selection takes at least one photo by type, so a post with no photo is not a representable input.
• pickMedia(files) — the same Select mode with photos and videos mixed (at least two files): a carousel with a video child, each file's kind read from its bytes.
• pickVideo(video) — one video; the app takes it through the creation camera's pass and publishes it as a reel (reel).
• switchMode(mode) — the selector's move to REEL or STORY, which opens the creation camera.

A file the app's picker does not offer, or one that carries a content-credentials manifest, an IPTC record or a generated-media source type, is the typed PostingMediaFormatError at the pick (Publishing). The picks' programs are on a post and a Reel.