Typing `@shot.png` in the line attaches that picture to the turn — no separate
command — and `@notes.txt` appends the file as text under a `--- @path ---`
header, capped like a tool result with a resumable `truncate_token`.
`@"my shot.png"` is the quoted form, and Tab completes the path after `@`
(directories end in `/`, a name with a space completes quoted).
An image is skipped, with a note naming the key to set, on a model without
`image_in`; a missing or denylisted path is a note too, and the turn still goes.
The default catalogs mark what can take a picture (`deepseek-flash` yes,
`deepseek-v4-pro` no, the OpenAI defaults yes).
`Agent.run` takes the parts, so the turn is stored with its images and shows up
as `[image]` wherever only prose is wanted.
