The reveal

Motion alone cannot establish how much work remains. A determinate HTML progress element exposes a value supplied by the page; that value may be a measured step count or an estimate, while an indeterminate one exposes no completion value.

You picked: —

In this run, Bar A exposed a value attribute; Bar B did not. That semantic difference was not visible in the motion, and a supplied value still does not prove a real backend task.

You committed to Bar A. Motion could not establish that Bar A knew more; the page only reveals its value state after your commitment.

You committed to Bar B. Motion could not establish that Bar B knew more; the page only reveals its value state after your commitment.

You treated convincing motion as evidence that both bars knew their remaining time. The animation carried no such guarantee.

You withheld a claim the motion could not support. That is the defensible boundary — but a value exposed later still needs a provenance check.

Your first run was stacked — the bar without a value got the lifelike stutter. Every rerun after that was a coin flip. Neither choreography nor side tells you where a value came from.

You marked Certain — on a question where certainty was never available.

Motion is not information.

The rebuilt model

Run it again — one variable

Keep the motion. Remove the semantic signal, then test which data source could justify a report.

Evidence

• WHATWG HTML Standard — The progress element

  The determinate and indeterminate states and the role of the value attribute.

  standard — checked 2026-07-19.
• MDN — <progress>: The Progress Indicator element

  Practical browser semantics and accessibility guidance for progress indicators.

  official-doc — checked 2026-07-19.

Evidence reviewed 2026-07-20. Corrections and review policy.

Scope: This page demonstrates the semantic states of the HTML progress element and the provenance boundary between a supplied value, an estimate, and timer-only choreography.

Does not prove: A value attribute does not prove that the application measured its real task correctly, an estimate is not a completed-work measurement, and an animation does not prove that any task is running.

Take it with you