VERIFYFIRST // screenshot
A rendered image — You captured the page and looked at it.

WHAT IT CAPTURES
  One frame's worth of pixels, at one viewport size, at one moment.

WHAT IT CANNOT SEE
  - Time. A still frame cannot distinguish 'renders one frame then stops' from 'renders one frame correctly'.
  - Whether scripts ran at all, as opposed to running and producing this.
  - Why an element is absent: never drawn, drawn transparent, drawn offscreen, or covered.
  - Which typeface actually resolved, when the fallback is also a real font.
  - Whether an asset arrived slowly or was requested late.

KNOWN FAILURES (6)

  NS-001  The compositor-free browser reports frozen animation as no animation
    reads as   A screenshot shows the element static. Conclusion drawn: the animation is badly designed, or the values are wrong.
    actually   requestAnimationFrame never fires because the headless browser has no compositor. Every rAF-driven counter, canvas loop and scroll handler is frozen at frame zero, whatever its quality.
    check      let n=0; requestAnimationFrame(()=>n++); setTimeout(()=>console.log('rAF fired:', n), 1000)

  NS-002  A var assignment silently overwrites a hoisted function of the same name
    reads as   A canvas is blank and unanimated. Conclusion drawn: a rendering or design problem.
    actually   The file already used `var start` as a timestamp. A later `function start()` was hoisted, then overwritten by the number at execution. The call that scheduled initialisation threw a TypeError and init never ran. The element sat at its untouched default size with zero painted pixels.
    check      Read the element's backing store, not its appearance: canvas.width/height still at the 300x150 default means resize() never ran.

  NS-004  A relative font URL resolves one directory too deep and fails into a plausible fallback
    reads as   Text renders in a serif. Conclusion drawn: the font loaded.
    actually   A stylesheet at /assets/fonts.css requesting url('assets/fonts/x.woff2') resolves to /assets/assets/fonts/x.woff2 and 404s. The browser substitutes a system serif without complaint.
    check      document.fonts.check('1em "Family Name"') or a 404 on the font path in the network log.

  NS-009  Assets are not slow, they are queued behind synchronous work
    reads as   Images take seconds to appear. Conclusion drawn: the images are too large.
    actually   Their request had not been issued. Heavy synchronous work earlier in the document held the main thread, and the fetch that would load them sat unsent behind it.
    check      performance.getEntriesByType('resource') — startTime separates 'requested late' from 'transferred slowly'.

  NS-010  Reveal-on-scroll renders a blank page when the observer never fires
    reads as   A page loads blank in an embedded or scripted context. Conclusion drawn: a rendering failure.
    actually   Elements start at opacity 0 and are revealed by an IntersectionObserver callback. Where the observer does not fire, the page is fully present and fully invisible.
    check      Compare element count against visible count: document.querySelectorAll('.reveal').length versus those with computed opacity above zero.

  NS-030  A transparent overlay takes the click the screenshot shows landing on the button
    reads as   The screenshot shows the button unobscured and correctly placed, and the click was dispatched without error. Conclusion drawn: the button was clicked.
    actually   A transparent element — a full-viewport modal backdrop, a zero-opacity loading layer, an oversized decorative pseudo-element — covers the button's centre point, and hit testing delivers the event to the topmost element at that coordinate. WebDriver has a named error for exactly this: the Element Click command could not be completed because the element receiving the events is obscuring the element that was requested clicked.
    check      Ask the document what occupies the point: `const r = el.getBoundingClientRect(); document.elementFromPoint(r.left + r.width/2, r.top + r.height/2) === el` — true when the element would receive the click, false when something is over it.

---
Full registry: https://verifyfirst.dev/registry.json
This page:     https://verifyfirst.dev/screenshot/
CC0-1.0. Every entry observed, none hypothetical.