Asc Screenshot Resize Agent Skill
Resize and validate App Store screenshots with current asc screenshot-size data and macOS sips. Use when preparing or fixing screenshots for App Store Connect submission.
Install
one command, takes just this skill from the repositorynpx skills add https://github.com/rorkai/app-store-connect-cli-skills --skill asc-screenshot-resizeThe instruction itself
9 sections, as written by the authorasc screenshot resize
Use this skill to prepare screenshots for App Store Connect. Do not rely on a hard-coded dimension table in this skill; the CLI owns the current size matrix.
Source of truth
Always discover current accepted sizes from asc first:
asc screenshots sizes --output table
asc screenshots sizes --all --output table
For local validation before upload:
asc screenshots validate --path "./screenshots/iphone" --device-type "IPHONE_65" --output table
asc screenshots validate --path "./screenshots/ipad" --device-type "IPAD_PRO_3GEN_129" --output table
Common current device-type anchors:
IPHONE_65for the common 6.5-inch iPhone screenshot set.IPAD_PRO_3GEN_129for the common 12.9/13-inch iPad screenshot set.
Run asc screenshots sizes --all when targeting other display types such as 6.9-inch iPhone, Apple TV, Mac, Vision Pro, iMessage, or Watch.
Workflow
1. Sanitize filenames
macOS screenshots can contain hidden Unicode spaces that make tools fail with "not a valid file". Sanitize before batch work:
python3 -c "
import os
for f in os.listdir('.'):
clean = f.replace('\u202f', ' ')
if f != clean:
os.rename(f, clean)
print(f'Renamed: {clean}')
"
2. Inspect dimensions and metadata
sips -g pixelWidth -g pixelHeight screenshot.png
sips -g hasAlpha -g space screenshot.png
App Store Connect rejects screenshots with alpha transparency. Strip alpha by round-tripping through JPEG:
sips -s format jpeg input.png --out /tmp/asc-screenshot-no-alpha.jpg
sips -s format png /tmp/asc-screenshot-no-alpha.jpg --out output.png
rm /tmp/asc-screenshot-no-alpha.jpg
Batch-strip alpha from PNGs:
for f in *.png; do
if sips -g hasAlpha "$f" | grep -q "yes"; then
sips -s format jpeg "$f" --out /tmp/asc-screenshot-no-alpha.jpg
sips -s format png /tmp/asc-screenshot-no-alpha.jpg --out "$f"
rm /tmp/asc-screenshot-no-alpha.jpg
echo "Stripped alpha: $f"
fi
done
3. Resize only after choosing a target from asc
Pick a width and height from asc screenshots sizes --all. sips -z takes height first, then width:
# Example: portrait IPHONE_65 1284 x 2778
sips -z 2778 1284 input.png --out output.png
Batch resize to a chosen target:
mkdir -p resized
for f in *.png; do
sips -z 2778 1284 "$f" --out "resized/$f"
done
4. Validate outputs with asc
sips -g pixelWidth -g pixelHeight -g hasAlpha resized/*.png
asc screenshots validate --path "./resized" --device-type "IPHONE_65" --output table
5. Upload only after validation
asc screenshots upload --version-localization "LOC_ID" --path "./resized" --device-type "IPHONE_65" --dry-run --output table
asc screenshots upload --version-localization "LOC_ID" --path "./resized" --device-type "IPHONE_65"
Guardrails
- Treat
asc screenshots sizes --allas authoritative; Apple size requirements change. - Do not stretch screenshots across incompatible aspect ratios unless the user accepts the visual tradeoff.
- Always output to a separate file or directory to preserve originals.
- Screenshots must be PNG or JPEG and must not include alpha transparency.
- Convert Display P3 or other color spaces to sRGB when needed:
sips -m "/System/Library/ColorSync/Profiles/sRGB IEC61966-2.1.icc" input.png --out output.png
- Prefer
asc screenshots validateover visual inspection before upload.
Other skills for the same job
different authors, same section of the catalogue
Use when the user explicitly asks for a desktop or system screenshot (full screen, specific app or window, or a pixel region), or when tool-specific capture capabilities are unavailable and an OS-level capture is needed.
Mirror an iOS Simulator into the Codex in-app browser and render SwiftUI previews from importable Swift packages in that simulator with hot reload. Use when a user wants to watch or interact with an iOS app in the browser, see a SwiftUI preview outside Xcode Canvas, iterate live on a preview, or capture browser-visible simulator proof.
Annotate UI screenshots with documentation callouts in Fellyph's established visual style — uniform-width orange arrows with white halos, double-stroke target outlines, numbered callout cards, dim overlays and a framed canvas. Use this whenever the user asks to annotate a screenshot, add arrows or callouts to a screenshot, create documentation images, highlight UI controls in a capture, or produce docs/tutorial visuals for Playground, Studio or any web UI — even if they just say "add arrows to this" or "make a docs screenshot".
Render pixel-accurate iMessage screenshot mockups (DM or group) from a thread JSON. Supports minimal, with-keyboard, and full iPhone 15 Pro frame variants. Outputs HTML + PNG.
> End-to-end skill that turns a single reference image into a published Gooseworks style — analyzes the image, drafts the slim style spec, renders a hero example plus 2-3 additional formats via Playwright, writes the `gooseworks-style.json` manifest, and publishes via `npx gooseworks styles publish` so other agents can discover it. Mirrors goose-graphics-create-format but for styles.
Generates an automated App Store screenshot pipeline with UI tests for screenshot capture, device framing, localized caption overlays, and multi-size batch export. Use when user wants automated screenshots, App Store screenshot generation, or a fastlane snapshot replacement.
Dependency checker and installer for agent-canvas, agent-eyes, and canvas-edit skills. Use BEFORE running any canvas skill for the first time, or when canvas skills fail with import/browser errors. Triggers on "setup agent canvas", "install canvas dependencies", "canvas not working", "playwright not found", or any setup/installation request for canvas skills.
Generate high-density editorial HTML info cards in a modern magazine and Swiss-international style, then capture them as ratio-specific screenshots. Use when the user provides text or core information and wants: (1) a complete responsive HTML info card, (2) the design to follow the stored editorial prompt, (3) output in fixed visual ratios such as 3:4, 4:3, 1:1, 16:9, 9:16, 2.35:1, 3:1, or 5:2, or (4) both HTML and a rendered PNG cover/card from the same content.
How to use it
Take rorkai/asc-screenshot-resize from the repository into ~/.claude/skills for personal
use, or into .claude/skills inside a project.
The agent identifies a skill by the name field in its header. Two skills with the
same name cannot sit side by side — one of them will be ignored.