defaultMaxLines constant
How many settled lines are kept per service — the pane's scrollback depth, since the oldest line reachable by scrolling is the oldest line still kept.
This was an invisible default until the pane could scroll, and 500 is
deliberately left where it was. A full Dart stack trace runs well under a
hundred lines, so 500 holds one whole with the build that preceded it —
which is as far as anyone reads before switching to the log file. Raising
it trades a real cost for depth nobody reaches: the cap is per service and
revali up runs the whole fleet, so it multiplies by ten, and lines
copies the entire buffer on every rebuild — which is once per chunk of
child output, for every service at once.
A service that scrolls to the very top and keeps printing will have lines
evicted out from under it; _settle keeps the view stationary while that
happens rather than letting it drift.
Implementation
static const defaultMaxLines = 500;