Each target's row shows its result as soon as its check ends (closes #91)

tick drew no row until the round's slowest check ended, up to 24
seconds at a 30-second interval since checks time out at 80% of it.
Each check now pushes its sample and redraws its row as it ends. When
the last check ends, every row is redrawn, so none still reads "paused"
after a pause and resume, and sorting, the summary, the health box and
offline detection run once. A check that ends while paused or after its
round is given up draws nothing, and the first round is still discarded
as a whole. The row is looked up when the check ends, as a pin click can
re-sort the rows mid-round.

Unit tests run tick on the mocked clock against a stand-in page.

Model: opus-5-5

src/main.js

@@ -263,7 +263,7 @@ class HostState {
     }
 }
 
-class AppState {
+export class AppState {
     constructor(localHosts) {
         this.wan = WAN_HOSTS.map(
             (h) => new HostState(h, h.name === "datavi.be"),
@@ -1105,7 +1105,7 @@ function sortAndRebuildWAN(state) {
 
 // --- Main Loop ---------------------------------------------------------------
 
-async function tick(state, signal, onOffline) {
+export async function tick(state, signal, onOffline) {
     const ts = Date.now();
 
     if (state.paused) {
@@ -1126,12 +1126,26 @@ async function tick(state, signal, onOffline) {
 
     log.debug(`Tick #${state.tickCount + 1} started`);
 
-    const results = await Promise.all(
-        state.allHosts.map((h) => measureLatency(h.url, signal)),
+    // Each host's row shows its result as soon as its check ends. The
+    // result is discarded if by then the user has paused or the next round
+    // has given up this one's checks, and in the first tick (tickCount is
+    // still 0), which is discarded as a whole below. The row is looked up
+    // when the check ends, as a pin click may have re-sorted the rows since
+    // the round started.
+    await Promise.all(
+        state.allHosts.map(async (host) => {
+            const r = await measureLatency(host.url, signal);
+            if (state.paused || signal.aborted || state.tickCount === 0) {
+                return;
+            }
+            host.pushSample(ts, r);
+            updateHostRow(host, state.allHosts.indexOf(host));
+            log.debug(`${host.name}: ${r.error ? r.error : r.latency + "ms"}`);
+        }),
     );
 
     // User may have paused, or the next round may have given up this
-    // one's checks, while awaiting results — discard them
+    // one's checks, while awaiting results — skip the rest of the round
     if (state.paused || signal.aborted) return;
 
     state.tickCount++;
@@ -1142,12 +1156,9 @@ async function tick(state, signal, onOffline) {
         return;
     }
 
-    state.allHosts.forEach((host, i) => {
-        const r = results[i];
-        host.pushSample(ts, r);
-        updateHostRow(host, i);
-        log.debug(`${host.name}: ${r.error ? r.error : r.latency + "ms"}`);
-    });
+    // Redraw every row: if the user paused and resumed during this round,
+    // rows whose check ended before the resume still read "paused"
+    state.allHosts.forEach((host, i) => updateHostRow(host, i));
 
     // Sort after the first real check, then every 10 ticks thereafter
     if (state.tickCount === 2 || state.tickCount % 10 === 1) {
@@ -1213,7 +1224,7 @@ function stopRecoveryProbe(state) {
 
 // --- Pause / Resume ----------------------------------------------------------
 
-function greyOutUI(state) {
+export function greyOutUI(state) {
     // Grey out all host rows
     state.allHosts.forEach((host, i) => {
         const latencyEl = document.querySelector(
@@ -1385,10 +1396,10 @@ async function init() {
     setInterval(updateClocks, 1000);
 
     // Rounds never overlap: a round first gives up the last round's checks
-    // if they are still waiting, and the last round then records nothing.
-    // At a steady interval they never are, as they time out at 80% of it;
-    // they can be when a round starts early, after an interval change or
-    // when the recovery probe finds a target answering.
+    // if they are still waiting, and the last round then records nothing
+    // more. At a steady interval they never are, as they time out at 80% of
+    // it; they can be when a round starts early, after an interval change
+    // or when the recovery probe finds a target answering.
     let roundChecks = new AbortController();
     function doTick() {
         roundChecks.abort();