Description
Scrolling capture with Auto Scroll can stitch the same content more than once. On long pages with repeated visual structure (GitHub markdown, headings, tables, code blocks), the saved image shows duplicated sections that are not in the live page.
Manual scrolling of the same region usually stitches cleanly. Auto Scroll is the path that goes wrong.
Steps to Reproduce
- Open a long GitHub markdown file in the browser (example:
vercel-labs/skills AGENTS.md).
- Start scrolling capture (
⇧⌘6) and select only the moving content.
- Lock the first frame, then turn on Auto Scroll.
- Let it run to the end and press Done (or let it auto-finish).
- Compare with a second capture of the same region using manual scrolling.
Expected Behavior
Auto Scroll should produce one continuous long screenshot. Each heading and paragraph should appear once, in page order, matching a careful manual-scroll capture.
Actual Behavior
The stitched image repeats blocks of content. Typical artifacts:
- The same heading appears twice in a row (
Improve existing skills, Test your skills locally).
- A later section jumps backward into content that was already captured.
- The stitcher has accepted a small false overlap while the page kept moving, so later frames stay pinned to the wrong delta.
Screenshots / Recordings
Reproduced on a GitHub markdown file: the Auto Scroll result duplicated section headings that the manual-scroll result did not.
Snapzy Version
1.32.0-beta.4 (built from source)
macOS Version
Other (specify in description)
Installation Method
Built from source
Additional Context
macOS 26. Auto Scroll currently posts wheel events continuously (-15px / 40ms) and stitches on opportunistic scroll-event commits. The page is often still animating when a frame is committed, so overlap is wrong. A small false match then becomes the prior for later frames, which duplicates sections.
A local fix is in progress: closed-loop steps (bounded scroll → settle → stitch), suppress mid-scroll commits, and stop the last accepted delta from overriding a known expected step. No PR yet.
Description
Scrolling capture with Auto Scroll can stitch the same content more than once. On long pages with repeated visual structure (GitHub markdown, headings, tables, code blocks), the saved image shows duplicated sections that are not in the live page.
Manual scrolling of the same region usually stitches cleanly. Auto Scroll is the path that goes wrong.
Steps to Reproduce
vercel-labs/skillsAGENTS.md).⇧⌘6) and select only the moving content.Expected Behavior
Auto Scroll should produce one continuous long screenshot. Each heading and paragraph should appear once, in page order, matching a careful manual-scroll capture.
Actual Behavior
The stitched image repeats blocks of content. Typical artifacts:
Improve existing skills,Test your skills locally).Screenshots / Recordings
Reproduced on a GitHub markdown file: the Auto Scroll result duplicated section headings that the manual-scroll result did not.
Snapzy Version
1.32.0-beta.4 (built from source)
macOS Version
Other (specify in description)
Installation Method
Built from source
Additional Context
macOS 26. Auto Scroll currently posts wheel events continuously (
-15px/ 40ms) and stitches on opportunistic scroll-event commits. The page is often still animating when a frame is committed, so overlap is wrong. A small false match then becomes the prior for later frames, which duplicates sections.A local fix is in progress: closed-loop steps (bounded scroll → settle → stitch), suppress mid-scroll commits, and stop the last accepted delta from overriding a known expected step. No PR yet.