Say what changes for somebody running a Bot people watch

The checklist in docs/development.md asks for this when a deployment behaves
differently afterwards, and it does: a computer that was stopped stays
stopped, a watched Bot stops being immune to the idle timeout and the cap,
and a viewer whose screen ends is told why.

It also says plainly that the app does not show that message yet, so nobody
reads this and expects to see it on screen.

Author: beardthelion

CHANGELOG.md

@@ -8,6 +8,30 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## Unreleased
 
+### Stopping a Bot's computer stops it, and the person watching is told
+
+A computer somebody stopped came back up on its own about a second later, and reset did the same. The
+live screen kept a loop asking for the Bot's current page once a second, asking for a page is what
+starts a browser, and nothing tore that loop down when the browser it was showing went away. The same
+loop kept the browser marked recently used, so a Bot with somebody watching was also immune to the
+idle timeout and came straight back after being closed to stay under the cap on running browsers.
+Those last two never involved a request at all, so nothing on the stop path could have covered them.
+
+Two smaller failures went with it. A person who reconnected, leaving their old window open, could
+have that old window's typing land in the page the new one was watching, with nothing said to either.
+And a window closed while the browser was still starting left a screencast and its loop behind for a
+connection that had already gone.
+
+The screen is now held per connection rather than per Bot, so closing one only ever ends its own, and
+teardown hangs off the browser closing rather than off the two requests that ask for it. A viewer
+whose screen ends is sent a message saying why, whether the computer stopped, was reset, or the
+screen was taken over by another window.
+
+Nothing to configure, and no change for a deployment where nobody watches a Bot work. **The app does
+not yet show that message**: it arrives at the browser and is held in state the live screen does not
+read, so a person still sees the last frame until they reopen the screen. That half is tracked
+separately in #287.
+
 ### The framework Bot answers on 5.6-tier models, and can be told how hard to think
 
 Pointing `BOT_MODEL` at a `gpt-5.6-*` model gave a Bot that started, reported healthy, and then said