fix(screenshot): scale full-page captures past the png budget

[Kikobeats]

Summary

• A full-page PNG of a very tall page (about 30k CSS px at 2x, ~150 megapixels) encodes past a 30s browser budget. https://www.wuling.com/carDetail?id=301 hit EBRWSRTIMEOUT that way. A JPEG of the same surface comes back empty from Chrome.
• When fullPage would exceed 40 megapixels, capture the document as a clip scaled to stay inside that budget. Shorter full pages stay at full resolution.

Test plan

• packages/screenshot/test/full-page-budget.js — a 20_000px page is scaled under 40 megapixels; a 400px page is not

Made with Cursor

Summary by CodeRabbit

• Bug Fixes
  • Full-page PNG screenshots of exceptionally large pages are now limited to 40 million pixels, reducing the risk of oversized captures. Smaller screenshots retain their expected dimensions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: defaults
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• Run ID: 71351c79-f70d-499b-8334-bbbd60d01c09

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📥 Commits

Reviewing files that changed from the base of the PR and between eecdb73 and 106ef4a.

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📒 Files selected for processing (2)

• packages/screenshot/src/index.js
• packages/screenshot/test/full-page-budget.js

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📝 Walkthrough

Walkthrough

Full-page PNG captures now use a 40-million-device-pixel limit. Captures above the limit use a proportional clip. Browser-backed tests check PNG validity and dimensions for captures above and below the limit.

Changes

Full-page PNG pixel budget

Layer / File(s)	Summary
Measure dimensions and adjust capture options packages/screenshot/src/index.js	For unclipped full-page captures, the code retains the original options when dimensions are invalid or the device-pixel area is within the limit. Above the limit, it sets a proportional clip and captureBeyondViewport, then removes fullPage.
Apply options and test PNG dimensions packages/screenshot/src/index.js, packages/screenshot/test/full-page-budget.js	captureExpanded applies the adjusted options before capture. Browser-backed tests check PNG validity and dimensions for pages above and below the limit.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

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Merge Risk: 🟡 Moderate · up to 106ef

In a supported runtime configuration with an unset viewport and a high device scale factor, the new guard can still allow an oversized full-page capture. Fix this edge case before merging so the pixel budget applies consistently.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: scaling full-page screenshot captures when they exceed the PNG pixel budget.
Docstring Coverage		No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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[coderabbitai]

Actionable comments posted: 2

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• 🪄 Fix CodeRabbit comments on this PR

🤖 Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
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Inline comments:
Review comments at @packages/screenshot/src/index.js:
- Line 245: Update the pixel-count calculation to obtain window.devicePixelRatio
alongside the document dimensions and use that value instead of relying on
page.viewport()?.deviceScaleFactor, which can be unavailable when the viewport
is null.

Review comments at @packages/screenshot/test/full-page-budget.js:
- Around line 42-43: Update the screenshot budget test so it verifies full-page
capture rather than allowing viewport-only images: at
packages/screenshot/test/full-page-budget.js lines 42–43, add a lower bound for
the scaled full-page height; at lines 47–47, use a below-budget page taller than
the viewport; and at lines 50–50, assert the expected full-page height for that
page.

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ℹ️ Review info

⚙️ Run configuration

• Configuration used: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: bcf5872d-90c0-4933-9b19-c9b0094d8e09

📥 Commits

Reviewing files that changed from the base of the PR and between 99015d0 and eecdb73.

📒 Files selected for processing (2)

• packages/screenshot/src/index.js
• packages/screenshot/test/full-page-budget.js

Included review availability: This review used your included allowance. Your plan provides up to 4 included reviews per hour; 3 remain after this review.

[coveralls]

coverage: 77.242%. first build — fix/full-page-png-budget into master