A chart can now ask for what it draws instead of reading the ring the
engine keeps. It publishes a request — the window and the resolution —
exactly as a slider publishes a value, and draws the series a flow
answers with. What serves the request is the flow's business, so the
widget never learns which database was behind it.
The answer says what it was computed for and one computed for another
window is ignored, so two charts on one node cost a duplicate query
rather than overwriting each other's picture. Identical requests still
in flight are asked once per tab, and the refresh has a floor under it.
The panel gains the presentation the document could already hold: the
per-series label, a unit, and a y axis that can be pinned.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>