pdf-diff

name	pdf-diff
description	Visual PDF regression test comparing current Beamer output against a baseline branch. Use when checking if slide changes introduced visual regressions.
argument-hint	[PaperName] [branch, default: main]
allowed-tools	["Read","Bash","Glob"]

Visual PDF Regression Test

Compare the current Beamer PDF output against a baseline branch to detect visual regressions.

Prerequisites

• diff-pdf must be installed (brew install diff-pdf)
• The paper's .tex file must compile successfully

Steps

Step 1: Parse arguments

• First argument: PaperName (required, e.g., SUNY, DreamZero)
• Second argument: baseline branch (optional, default: main)

Step 2: Compile current version

cd /Users/iyunseong/maangeek/paper2pr/Slides
TEXINPUTS=../Preambles:$TEXINPUTS xelatex -interaction=nonstopmode $PAPER.tex
cp $PAPER.pdf /tmp/${PAPER}_current.pdf

Step 3: Get baseline version

cd /Users/iyunseong/maangeek/paper2pr
git stash --include-untracked
git checkout $BRANCH -- Slides/$PAPER.tex
cd Slides
TEXINPUTS=../Preambles:$TEXINPUTS xelatex -interaction=nonstopmode $PAPER.tex
cp $PAPER.pdf /tmp/${PAPER}_baseline.pdf
git checkout - -- Slides/$PAPER.tex
git stash pop

Step 4: Run diff-pdf

diff-pdf --output-diff=/tmp/${PAPER}_diff.pdf /tmp/${PAPER}_baseline.pdf /tmp/${PAPER}_current.pdf
echo "Exit code: $?"

• Exit code 0: PDFs are visually identical
• Exit code 1: Visual differences detected (diff PDF saved)

Step 5: Report results

• If identical: "No visual regressions detected."
• If different: "Visual differences found. Diff PDF saved to /tmp/${PAPER}_diff.pdf"
  • Open the diff PDF: open /tmp/${PAPER}_diff.pdf
  • Differences are highlighted in red

Step 6: Cleanup

rm -f /tmp/${PAPER}_current.pdf /tmp/${PAPER}_baseline.pdf

Keep the diff PDF for review if differences were found.

Notes

• This compares full visual output, including fonts, spacing, and figure rendering
• Single-pass XeLaTeX is sufficient for visual comparison (no bibtex needed)
• For multi-page diffs, diff-pdf --skip-identical shows only changed pages