08 — Water Tank Multi-Page

Same simulation as 07, but with a second page (/diagnostics) that displays accumulated counters and a level history table. Both pages are independently polled by HTTP Refresh headers, so /diagnostics keeps refreshing itself rather than ping-ponging back to the schematic.

Interactivity level: 3 — Polling (whole page refresh, per-page) State scope: Global (server build) / Individual (WASM build)

Launch Demo Source on Codeberg

Schematic page — pump filling, level 30% — / — schematic

→

Diagnostics page — counters and level history table — /diagnostics — counters & history

Same simulation, two views: the schematic page polls /, the diagnostics page polls /diagnostics. Both views read from the same shared Simulation. The schematic uses the shared watertank widget; the diagnostics view is rendered straight to the buffer via lofigui.Print/Table.

Diagnostics counters

Simulation accumulates pump/valve cycles, on-time durations, and a rolling level history. Diagnostics() returns a DiagSnapshot for the diagnostics page to render:

type DiagSnapshot struct {
    PumpCycles  int
    PumpOnTime  time.Duration
    ValveCycles int
    ValveOnTime time.Duration
    FloatTrips  int
    TickCount   int
    History     []LevelEntry
}

The level history is kept down-sampled (one entry every N ticks) so the table stays a manageable size.

Multi-page refresh

The Refresh header reloads whichever URL the browser was on, so each page polls itself:

GET /             → renderSchematic() → app.HandleDisplay(w, r)
GET /diagnostics  → renderDiagnostics() → app.HandleDisplay(w, r)

app.HandleDisplay writes a Refresh header pointing at r.URL.Path. Hitting /diagnostics keeps refreshing /diagnostics; hitting / keeps refreshing /. Add a third page and it just works.

Source on Codeberg

Running

task go-example:08         # server on :1348
task docs:capture:08       # capture the two screenshots above