ci: Add CircleCI image download script

.circleci/config.yml

@@ -303,6 +303,7 @@ jobs:
       - run:
           name: Compare pixels
           command: .circleci/test.sh test-image ; find build -maxdepth 1 -type f -delete
+      - image-diff-message
       - store_artifacts:
           path: build
           destination: /
@@ -317,6 +318,7 @@ jobs:
       - run:
           name: Compare pixels
           command: .circleci/test.sh test-image-virtual-webgl ; find build -maxdepth 1 -type f -delete
+      - image-diff-message
       - store_artifacts:
           path: build
           destination: /
@@ -331,6 +333,7 @@ jobs:
       - run:
           name: Compare pixels
           command: .circleci/test.sh test-image ; find build -maxdepth 1 -type f -delete
+      - image-diff-message
       - store_artifacts:
           path: build
           destination: /
@@ -345,6 +348,7 @@ jobs:
       - run:
           name: Compare pixels of mathjax v3 baselines
           command: .circleci/test.sh test-image-mathjax3
+      - image-diff-message
       - store_artifacts:
           path: build
           destination: /
@@ -515,6 +519,16 @@ jobs:
       - store_artifacts:
           path: topojson.tar
 
+commands:
+  image-diff-message:
+    steps:
+      - run:
+          name: IMAGE DIFF DETECTED - SEE NOTE BELOW
+          when: on_fail
+          command: |
+            echo "Image Diff Detected: baseline images may need to be updated. Run 'tasks/circleci_image_artifact_download.sh' to download the baseline images generated by this job."
+            echo "Add the new images to 'test/image/baselines/' and commit them to this pull request."
+
 workflows:
   version: 2
   build-and-test:

tasks/circleci_image_artifact_download.sh

@@ -0,0 +1,36 @@
+#!/usr/bin/env bash
+
+# Usage: $ ./circleci_image_artifact_download.sh JOB_NUMBER DEST_DIR
+
+# The job number is shown on the job page in the navigation breadcrumbs under 'Job':
+# ...   Job
+# ... > test-baselines (123456)
+# It's also shown in the URL: '.../jobs/123456/...'
+
+set -euo pipefail
+
+# Arguments
+JOB_NUMBER="${1:-}"
+DEST_DIR="${2:-.}"
+
+# Check if job number is provided
+if [[ -z "$JOB_NUMBER" ]]; then
+  echo "CircleCI job number required. Usage: $0 <job-number> [destination-directory]"
+  exit 1
+fi
+
+mkdir -p "$DEST_DIR"
+cd "$DEST_DIR"
+
+# Get list of artifact URLs (filtering for .png files not containing 'diff')
+artifact_urls=$(curl https://circleci.com/api/v2/project/github/plotly/plotly.js/$JOB_NUMBER/artifacts \
+  | grep -oE "https.*png" \
+  | grep -v "diff")
+
+# Download each artifact
+echo "$artifact_urls" | while read -r url; do
+  echo "Downloading $url..."
+  curl -s -L -O "$url"
+done
+
+echo "✅ All PNG artifacts saved to: $DEST_DIR"