fix(engine): prevent CDP screenshot viewport edge bleed#1037
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miguel-heygen wants to merge 1 commit into
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fix(engine): prevent CDP screenshot viewport edge bleed#1037miguel-heygen wants to merge 1 commit into
miguel-heygen wants to merge 1 commit into
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Change captureBeyondViewport from false to true in pageScreenshotCapture. The explicit clip rect already constrains output to exact viewport dimensions, making the additional viewport-boundary clipping from captureBeyondViewport:false redundant. Under compositor load (especially multi-worker parallelism), Chrome occasionally rounds the viewport boundary inward by 1-2px before applying the clip, exposing the body background at the bottom/right edge of the captured frame. With captureBeyondViewport:true, Chrome skips the viewport-boundary pre-clip and uses only the explicit clip rect, eliminating the intermittent edge bleed. Add viewport-edge-bleed regression test: a magenta body background with dark grid cells filling 1920×1080 edge-to-edge. Any background bleed at the edges drops PSNR sharply against the golden baseline.
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Summary
Fixes an intermittent rendering artifact where 1-2px of body background bleeds through at the bottom/right edge of captured frames.
Root cause:
pageScreenshotCapture()inscreenshotService.tspassescaptureBeyondViewport: falseto Chrome's CDPPage.captureScreenshot. This adds a viewport-boundary pre-clip before the explicit clip rect is applied. Under compositor load (especially multi-worker parallelism), Chrome occasionally rounds that viewport boundary inward by 1-2px, exposing the body background at the edges.Fix: Change
captureBeyondViewporttotrue. The explicit clip rect{x:0, y:0, width, height, scale:dpr}already constrains output to exact viewport dimensions — the redundant viewport boundary clip was only causing problems.Changes
packages/engine/src/services/screenshotService.ts:captureBeyondViewport: false→trueinpageScreenshotCapture()viewport-edge-bleed: magenta body background with dark grid cells edge-to-edge. Any background bleed drops PSNR sharply.Test plan
bun run --cwd packages/producer docker:test viewport-edge-bleed