List files in the user's workspace.

When session_id is provided, only files for that session are returned. Otherwise, all files across sessions are listed. Results are paginated via limit/offset; has_more indicates whether additional pages exist.

The Artifacts page uses q for name search and origin to filter between Uploaded (user-uploaded) and Generated (agent/block output) files.

session_id (a per-session view) and the folder filters (folder_id / root_only) are distinct, mutually exclusive axes, and folder_id and root_only likewise conflict; passing conflicting filters returns a 400 rather than silently yielding an empty list.

expert_id narrows the listing to that hired expert's own conversations. It conflicts with session_id — both name which conversations to show — but composes with the folder filters, which select across the whole workspace. An expert the caller does not own (or no longer has) yields an empty list.

include_user_files widens an expert_id listing with the user's own files, which an expert may read but which are nobody's conversation. It is opt-in so that a view already filtered to one expert keeps showing that expert's files and nothing else; the composer's picker sends it when its "only this expert" filter is switched off.

The listing is of the user's files: skill packages and Otto's working files (isInternal, decided when each file is written) are left out in the query, so paging stays correct. include_internal lists them too, for a view that shows them apart.