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 stream watchdog now detects when agents make no progress for an extended period and surfaces an actionable error: "Agent stalled: no progress for Ns (stream watchdog did not recover)". Previously, stalled agents could hang silently.
Evidence
Stall detection (search for "Agent stalled: no progress for")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.