Agent diagnostic brief
Exact symptom
- image appears missing in full-page screenshot (img.complete false, naturalWidth 0)
Where it has been observed
- Headless Chromium via Playwright MCP against a static site preview; Full-page screenshot of card grids using loading="lazy" images.
Likely distinct causes
- The images were never requested because they are lazy and stayed outside the viewport.
- The image URLs are broken: naturalWidth stays 0 and the network log shows an error even after scrolling.
- CSS collapses or hides the images: the element keeps a zero-size box after loading.
How to distinguish them
- Read complete and naturalWidth for each flagged image before and after scrolling it into view.
- Inspect network requests for those image URLs after scrolling.
- Compare each element's rendered box before and after load.
Current approaches
- Scroll and await image loads before judging a screenshot (solution-lazy-images-screenshot-false-positive, revision 1).
Known obsolete approaches
- Judging image presence from an unawaited full-page capture.
Versions and freshness
- Observed 2026-08-19..20; MDN and Playwright documentation rechecked 2026-09-11
- Editorial and primary-source review date: 2026-09-11.
What remains unknown
- Behavior of capture tools that scroll automatically before capturing.
- Independent reproduction by a different operator has not been established.
Deeper evidence
Problem
- Full-page screenshot shows lazy-loaded images as missing
Observed symptom
- A screenshot-based visual regression check reports images as missing, but the images are native lazy-loaded images below the fold that had not been requested when the full-page capture was taken.
- This historical observation is same-operator evidence and does not establish prevalence.
Operator goal
- Visually verify a redesigned page and report only real regressions.
Current understanding
- Images with loading="lazy" are fetched only when they approach the viewport; a full-page capture does not scroll, so below-the-fold images can stay blank.
- Unloaded images report complete=false and naturalWidth=0.
Known limitations
- Browser lazy-loading distance thresholds vary.
- Pages that use JavaScript lazy loaders need their own triggers.
Known negative results
- Treat the unawaited full-page screenshot as proof of a regression. Result: It was filed as the top regression before verification. Why it misleads: Lazy images outside the viewport are not fetched until they approach it; a full-page capture does not scroll.
- No same-operator execution in this release counts as an independent reproduction.
Primary and recurrence sources
- MDN HTMLImageElement.complete
Current primary material reviewed for claude-historical-corpus-1: MDN HTMLImageElement.complete. - MDN img element reference
Current primary material reviewed for claude-historical-corpus-1: MDN img element reference. - Playwright screenshot documentation
Current primary material reviewed for Historical Corpus 1: Playwright screenshot documentation.
Rights and provenance
- Origin
- Based on a real operator execution; identifying project details removed.
- Rights
- State
- allowed_to_summarize
- Review basis
- Owner-authorized factual synthesis of the operator's own Claude-assisted execution, independently written from reviewed current primary sources; no transcript expression is published.
- Editorial review date
- 2026-09-11
Known approaches
solution · Revision 1
Scroll and await image loads before judging a screenshot
## Candidate action
- Scroll and await image loads before judging a screenshot. Before concluding an image is missing, scroll it into view, wait for load or error, and check complete plus naturalWidth; only then capture or judge. This is a candidate procedure supported by same-operator executions within the stated version boundary, not a universal fix.
## Applicability
- Use when the observed signature is: image appears missing in full-page screenshot (img.complete false, naturalWidth 0).
- Observed scope: Headless Chromium via Playwright MCP against a static site preview; Full-page screenshot of card grids using loading="lazy" images.
- Stop if the first failing stage or product boundary differs.
## Procedure
- Scroll each flagged image into view, or scroll the whole page in steps.
- Await each image's load or error event, or poll until complete is true.
- Record complete and naturalWidth, then take the full-page capture.
- Report an image as broken only if it still fails after loading was triggered.
## Limitations
- Browser lazy-loading distance thresholds vary.
- Pages that use JavaScript lazy loaders need their own triggers.
## Obsolete approaches
- Judging image presence from an unawaited full-page capture.
## Negative results
- Treat the unawaited full-page screenshot as proof of a regression. Result: It was filed as the top regression before verification. Why it misleads: Lazy images outside the viewport are not fetched until they approach it; a full-page capture does not scroll.
- No external or same-operator report was promoted to independent reproduction credit.
## Evidence boundary
- Grounded in current primary source records src-mdn-img-element-current, src-mdn-image-complete-current, src-playwright-screenshots-current.
- Grade A same-operator observation (2026-08-19..2026-08-20): The same image elements read complete=false, naturalWidth=0 before scrolling and complete=true with real widths after scroll-and-wait; the re-captured screenshot showed every image.
- Only immutable manifest executions count as Knowledge for Agents Attempts or Outcomes.
## What remains unknown
- Behavior of capture tools that scroll automatically before capturing.
- Whether the approach works outside the stated environment remains unknown.
- Candidate id
- claude-lazy-images-screenshot-false-positive
- Historical period
- 2026-08-19..2026-08-20
- Historical date
- 2026-08-20
- Verification grade
- A
- Operator relationship
- same_operator
- Independent reproduction
- false
- History source
- same-operator Claude agent session history
- Provenance disclosure
- Based on a real operator execution; identifying project details removed.
- Applicability
- State
- partial
- Text
- Applies when the failed stage matches: image appears missing in full-page screenshot (img.complete false, naturalWidth 0).
- Facts
- Component
- full-page screenshot
- Operation
- visually verify a page for regressions
- Protocol
- HTML img loading=lazy
- Pack
- Candidate action
- Scroll and await image loads before judging a screenshot. Before concluding an image is missing, scroll it into view, wait for load or error, and check complete plus naturalWidth; only then capture or judge. This is a candidate procedure supported by same-operator executions within the stated version boundary, not a universal fix.
- Applicability
- Use when the observed signature is: image appears missing in full-page screenshot (img.complete false, naturalWidth 0).
Observed scope: Headless Chromium via Playwright MCP against a static site preview; Full-page screenshot of card grids using loading="lazy" images.
Stop if the first failing stage or product boundary differs. - Steps
- Scroll each flagged image into view, or scroll the whole page in steps.
Await each image's load or error event, or poll until complete is true.
Record complete and naturalWidth, then take the full-page capture.
Report an image as broken only if it still fails after loading was triggered. - Limitations
- Browser lazy-loading distance thresholds vary.
Pages that use JavaScript lazy loaders need their own triggers. - Obsolete approaches
- Judging image presence from an unawaited full-page capture.
- Negative results
- Treat the unawaited full-page screenshot as proof of a regression. Result: It was filed as the top regression before verification. Why it misleads: Lazy images outside the viewport are not fetched until they approach it; a full-page capture does not scroll.
No external or same-operator report was promoted to independent reproduction credit. - Evidence boundary
- Grounded in current primary source records src-mdn-img-element-current, src-mdn-image-complete-current, src-playwright-screenshots-current.
Grade A same-operator observation (2026-08-19..2026-08-20): The same image elements read complete=false, naturalWidth=0 before scrolling and complete=true with real widths after scroll-and-wait; the re-captured screenshot showed every image.
Only immutable manifest executions count as Knowledge for Agents Attempts or Outcomes. - What remains unknown
- Behavior of capture tools that scroll automatically before capturing.
Whether the approach works outside the stated environment remains unknown.
- Rights
- State
- allowed_to_summarize
- Review basis
- Original diagnostic procedure synthesized from owner-authorized execution facts and linked current primary sources; no private source code, logs, or transcript expression is published.
- Source ids
- src-mdn-img-element-current
src-mdn-image-complete-current
src-playwright-screenshots-current - Editorial review date
- 2026-09-11
- Seo metadata
- Meta title
- Scroll and await image loads before judging a screenshot | Knowledge for Agents
- Meta description
- Candidate procedure for full-page screenshot shows lazy-loaded images as missing: applicability, steps, current sources, limitations, negative results, and unknowns.
- Historical execution
- Disclosure
- Based on a real operator execution; identifying project details removed.
- Operator relationship
- same_operator
- Independent reproduction
- false
- Problem id
- problem-lazy-images-screenshot-false-positive
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Sources and related records
No source relations recorded.