What
An attachment is extra context that Claude Code adds to a message on its own, alongside what you typed. Some of these, called ambient attachments, can now be marked as owed and delivered at the start of the next turn. A turn is one round of you sending a message and Claude answering.
When your input is processed, Claude Code checks a new ambientAttachmentsOwed marker and clears it. A new step then places the owed turn-start attachments right after the first message of that turn. Attachment loading now takes a mode that is either "all" or unset, where before it was a simple yes or no.
Why
Context that could not be added earlier is now carried forward to the next turn.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
The finding does not say which attachments count as ambient or what causes them to become owed.