Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add Xopoko/build-swift-apps --skill appstore-screenshot-validatorgit clone --depth 1 https://github.com/Xopoko/build-swift-appsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/xopoko/build-swift-apps/appstore-screenshot-validator)<a href="https://agentmods.dev/skills/xopoko/build-swift-apps/appstore-screenshot-validator"><img src="https://agentmods.dev/badge/skills/xopoko/build-swift-apps/appstore-screenshot-validator/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/xopoko/build-swift-apps/appstore-screenshot-validator"><img src="https://agentmods.dev/badge/skills/xopoko/build-swift-apps/appstore-screenshot-validator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00038 | $0.00561 |
| Opus 5 | $0.00019 | $0.00280 |
| Sonnet 5 | $0.00008 | $0.00112 |
| Haiku 4.5 | $0.00004 | $0.00056 |
Grade A, and why
appstore-screenshot-validator scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 51 lines — stays where its author put it; the contents beside it link to each section on GitHub.
App Store Screenshot Validator
Before invoking Apple-only binaries, confirm the execution context is macOS. From Windows or Linux, run those steps in a Mac SSH project or through an already configured remote transport; do not retry missing Apple binaries locally.
Prepare screenshots for App Store Connect. Do not hard-code Apple size tables here; asc screenshots sizes is the source of truth.
Source Of Truth
asc screenshots sizes --output table
asc screenshots sizes --all --output table
For apps that run on each device family, the current required anchors are the
iPhone 6.9-inch slot (IPHONE_69) and iPad 13-inch slot
(IPAD_PRO_3GEN_129). Apple accepts the iPhone 6.5-inch slot when 6.9-inch
screenshots are not provided. Use --all for every accepted iPhone size, Apple
TV, Mac, Vision Pro, iMessage, or Watch slot.
Local Audit Helper
After choosing target dimensions from ASC, inspect local screenshots with the bundled helper:
python3 "$PLUGIN_ROOT/skills/appstore-screenshot-validator/scripts/screenshot_audit.py" \
"./screenshots/iphone" --recursive --allow-size 1290x2796 --allow-rotated --fail-on-alpha
The helper reads PNG/JPEG headers only. It does not resize, rewrite, strip alpha, upload, or call ASC. Pass --json for machine-readable output.
Workflow
- Query current screenshot size requirements with
asc screenshots sizes --all. - Run
screenshot_audit.pyagainst candidate PNG/JPEG files; fail on alpha and hidden Unicode filename spaces before upload. - Preserve originals. Write sanitized, alpha-stripped, resized, or color-converted images to a separate directory.
- Use
sipsfor macOS image rewrites only after selecting an ASC target size;sips -ztakes height then width. - Run
asc screenshots validateon the final directory, thenasc screenshots upload --dry-run, then upload only after the dry-run is clean.
Guardrails
Preserve originals by writing to a separate directory. Do not stretch across incompatible aspect ratios unless the user accepts the visual tradeoff. Prefer asc screenshots validate over visual inspection before upload.
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 11d ago First seen · 51 lines · 38 tokens per session scan A 1d41dbcfec85
appstore-screenshot-validator is a skill published in the GitHub repository Xopoko/build-swift-apps (45 stars, last pushed 14d ago), licensed MIT. It adds 38 tokens to every session and 561 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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