Worker results may report image attachments stored inside the workspace;
the runtime validates them (containment, png/jpg magic, size) and
delivers them with the pending event. Assistants gain a send_image
action so users can ask for an image later. QQ uploads via /files with
base64 file_data and sends msg_type 7 rich media, sharing the same
msg_id/msg_seq counter as text replies; non-image adapters flatten
images to text.
Proposal semantics: worker results no longer distinguish success/fail;
only an explicit finish settles a pending proposal. Pending owner input
follows up by resuming the original worker session. Dirty pending blocks
start_next globally; clean pending only blocks its owner.
QQ adapter now downloads image attachments and passes them as ACP image
content blocks; video/file attachments degrade to link text.
zenord