DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
The inbox polling system (used for processing queued messages when the session becomes available) has been refactored to accept an explicit enabled parameter. This improves control flow by allowing the polling behavior to be conditionally disabled rather than relying on implicit checks throughout the function.
Evidence
Inbox poller function signature change — ijq() at line ~547956 (search for "[InboxPoller]")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.