Nothing to try yetTier: how much it should matter to you
2Useful: my rating, 1 to 5
5Signal: worth watching, 1 to 5
ToolsArea: what it touches
In DevelopmentKind: in v2.1.248,
What probably matters to youSection of the release
The Monitor tool is described in full but conditionally available.
What
A Monitor tool is now fully described in the build: user-facing name "Monitor", allowed to run code, results capped at 10,000 characters, deferrable, safe to run concurrently, and it tells the model it will be notified on each event so it should keep working rather than poll.
Details
Availability is the conjunction of two runtime checks, so the tool is not unconditionally on; neither check is resolved in this build.
Evidence
You will be notified on each event. Keep working — do not poll or sleep.
Strings lifted out of the shipped bundle, so the claim above can be checked against them.