Top wears the skin; the refresh rate reaches every machine; bug bash 4

The process table's columns fit the box they are in, the rate control saves, curves are
timed on the viewer's clock and keep to the stride, the power icon is drawn, and a young
history draws in from the right instead of being stretched.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

SENSORS.md

@@ -206,7 +206,17 @@ with their name set into the border, curves drawn as dots that climb green → y
 It reads nothing of its own — the sensor stream for everything measured, `/api/procs` for the
 table — so it works on any machine the console can reach, whether or not btop is installed
 there, and it follows the same refresh rate and history window as the rest of the console.
-(The look is btop's, `web/src/Top.tsx` is ours; btop itself is Apache-2.0.)
+Its colours are the active skin's: the terminal background for the ground, the skin's sixteen
+terminal colours for the curves and meters. (The look is btop's, `web/src/Top.tsx` is ours;
+btop itself is Apache-2.0.)
+
+## How often a machine samples
+
+The console's refresh rate (Settings, or `− rate +` on Top) is also the fleet's sampling rate.
+It is saved with the UI prefs on the hub, which sets its own sampler and passes the rate to
+every machine it manages — `PUT /api/prefs/sampler {"ms": …}`, 100 ms to 60 s, sampled no
+slower than the collector's 10 s — and repeats it at start-up. `GET` answers `{ms, min_ms,
+max_ms}`. Before 2026-09-21 only an open Dashboard page told a machine its rate.
 
 ## How far back a history reaches