Walk & Test: destination cards, warm-up discard, 1s tick; drop the traffic monitor

[TechLuddite]

Three changes from testing the deployed build on a real network, plus one bug the browser run caught.

1. Facebook out, Atlassian in

Facebook did not respond on a healthy network. Meta domains sit on most ad and tracker blocklists, so that card failed for reasons that had nothing to do with the network path, and a false alarm in a diagnostic is worse than one fewer destination.

Atlassian replaces it: a business staple that is not commonly filtered, answering 200 terminally, and riding a different edge network from anything else in the list, which adds path diversity. The list is now four consumer and six business, and a test pins the blocklist-prone hosts out of it.

The card copy and both disclosure lists now name the blocklist case explicitly, since "unanswered" has one more cause a reader should know about.

2. A card per destination

Replaces the live table. Each card carries the last round trip, answered count, median, jitter and max, plus a sparkline in the style of the dashboard's traffic monitor. One to five columns depending on width.

Every sparkline shares one y-scale, printed above the grid. Per-card scaling would make a 400 ms destination and a 40 ms destination draw the same shape, which defeats the point of showing ten at once. A destination with nothing measured draws no line at all, because a flat trace along the bottom reads as "instant".

Warm-up rounds are discarded

The first two rounds, plus each destination's first answered probe, carry DNS, TCP and TLS. Left in, they pinned the top of every scale near a second for the rest of the session and flattened the real measurements into a line along the bottom, which is the "graph never recovers" problem.

They are counted and shown as discarded, never deleted: a destination that failed during warm-up still failed. Keying the setup flag on the first answer rather than the first attempt also fixes a destination that is silent for twenty rounds and then replies, which pays its handshake on round twenty-one. Charts additionally window to the last 60 rounds, so one spike cannot hold the axis for a whole walk.

One-second interval

Safe because the loop awaits a whole round before starting the timer, so the interval is a gap between rounds rather than a fixed cadence, and a struggling link stretches it rather than piling requests up. Measured at 1.10 s per round with all ten cards charting, and 104 ms click latency during it.

3. Live Traffic Monitor removed

Gone from the dashboard, with docs/REMOVED-TRAFFIC-MONITOR.md as the reference record: what it showed, how the PerformanceObserver aggregation worked, the || 1 latency bug it once had, why it went, and what would need fixing first if it came back.

It was passive, so its numbers described NetReady's own activity rather than the network, and it needed a traffic-generating button to look useful on an idle tab. Walk & Test is the active version done properly.

Its httpbin.org disclosure was rewritten rather than deleted: httpbin is still reachable as one of the HTTP Probe's one-click sample targets, so removing the row would have understated the app's reach. The disclosure list has to stay exactly as wide as what the app actually touches.

A bug the browser run caught

Offline, the shared-scale caption read "0 to 10 ms" — a chart-axis default that no probe produced, sitting on a page where every other figure was correctly an em-dash. The scale is now null when nothing has been measured and the caption says so instead.

Verification

• npm run check green. 308 tests, 10 new.
• Offline: zero occurrences of "N ms" anywhere on the page, verified by scanning the whole body rather than the table that no longer exists. 62 em-dashes, every card reading "no answer from this destination".
• Simulated two-spot walk with the first two rounds at ~930 ms to exercise the discard: the shared scale settled at 450 ms rather than 1000 ms, and the aggregate line correctly starts at round 3.
• Dashboard confirmed clear of the traffic monitor, with the Walk & Test card still present.

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