board-delivery

How the hot /api/board surface reaches its clients cheaply — the payload stays a lean summary and freshness is pushed, not polled.

raw source

/api/board is the dashboard's single source and its hottest fetch, so its wire cost is a product concern of its own: the snapshot once shipped over a megabyte of detail the overview never renders, re-fetched on a blind timer. Delivery — what the payload carries and when a client re-fetches it — is one seam, distinct from what the board contains (assembly stays with sessions).

expanded spec

Two halves of one budget:

• board-lean — the payload: the board carries only the summary the graph overview actually renders; per-node detail is lazy-loaded where it is viewed, and stays fresh by construction.
• board-stream — the freshness: a push signal fires on real change so the client re-fetches on transition instead of a tight poll, with conditional requests keeping a no-change reload bodyless.

The two compound: the stream decides when the wire is paid, the lean payload decides how much — together they take the board from megabyte-every-poll toward a small, mostly-static summary fetched only on change. Neither owns the board's contents (sessions) nor the slow cold-path poll for tree reshapes (dashboard-shell); this group owns only the wire between the board and its viewers.