Codex · App Store Connect

Make and upload App Store screenshots from Codex

Point Codex at your raw simulator captures. MetaRun's Screenshot Studio lays them out in device frames with captions, translates the captions, renders every slide on the server, and uploads them to App Store Connect once you approve.

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Setup checked October 2026 against Codex MCP docs, non-interactive mode

01 · Uplink

Connect Codex once

01 · Add the server

Codex sees that MetaRun offers sign-in and starts it straight away, in your browser. Pick read-only or read and change.

codex mcp add metarun --url https://metarun.dev/api/mcp

02 · Sign in again later

If the sign-in expires or you disconnected it in MetaRun's settings. --no-browser prints the link instead, for SSH sessions.

codex mcp login metarun

03 · Or edit ~/.codex/config.toml

The Codex CLI, the IDE extension and Codex in the ChatGPT desktop app read the same file, so one entry covers all three.

[mcp_servers.metarun]
url = "https://metarun.dev/api/mcp"

Prefer a personal access token (scripts, CI)?

Add the server with a token

Mint a personal access token in MetaRun under Settings, MCP. It's shown once and can be revoked any time. Codex reads it from the environment variable you name.

export METARUN_TOKEN="mr_pat_..."
codex mcp add metarun --url https://metarun.dev/api/mcp --bearer-token-env-var METARUN_TOKEN

Or in config.toml

[mcp_servers.metarun]
url = "https://metarun.dev/api/mcp"
bearer_token_env_var = "METARUN_TOKEN"

02 · Briefing

What Codex handles here

Screenshots are the part of a release people dread: frame every capture, write captions that fit, redo it all per language, export at Apple's sizes, then upload ten images per display size per language by hand.

MetaRun's studio is fully tool-driven, so Codex can build a project, apply a template, set captions, translate them, render previews you can look at, and then upload. Uploads go through the same preview gate as every other write.

03 · Preflight

Before you start

Raw captures of your app: simulator screenshots, UI test output or exported images.
An editable version to upload to.
For iPhone Duo, app previews or creative assets: the App Asset Library tools.

04 · Execution

How it runs

01
Start from your captures
Local files get an https URL with npx metarun upload, or the studio's own upload tools. Codex creates a project and assigns one capture per slide.
02
Design and caption
The agent applies a template and writes captions. Every slide can be rendered on the server and returned as an image, so you see the real result in the conversation.
03
Translate
Captions are translated per language, and the lint flags text that overflows its frame in a longer language.
04
Upload behind a preview
Each upload previews the target set, size and position. The confirm token is bound to the image bytes, so what you approved is exactly what reaches Apple.

05 · Session

An example session in Codex

Use the PNGs in fastlane/screenshots/en-US to build a 6-slide screenshot set with the Keynote template. Write captions from our feature list in README.md.

studio_create_projectProject created with six slides, one capture each.
Codex asks before running studio_apply_template. You read the preview above and approve.
studio_apply_templateKeynote template applied: background, device frame, caption type.
studio_render_slideSlide 1 rendered at 1320 x 2868 and shown in the conversation.
apple_preview_upload_screenshotPreview: slide 1 to the iPhone 6.9-inch set, English (U.S.), position 1.
Codex asks before running apple_apply_upload_screenshot. You read the preview above and approve.
apple_apply_upload_screenshotUploaded. Apple is processing the image.

Illustrative: your apps, versions and numbers will differ. The tool names and their order are real.

06 · Tools

The MetaRun tools Codex calls

Tool	What it does
studio_create_projectMetaRun	A new screenshot project for the app.
studio_apply_templateMetaRun	One of eight complete designs: background, device placement, caption type.
studio_set_slide_textMetaRun	Captions per slide and per language.
studio_translate_slidesMetaRun	Translate every caption into the project's languages.
studio_render_slideMetaRun	Render a slide on the server so you can see it before anything uploads.
studio_lint_assetsread	Check captions against Apple's asset rules.
apple_preview_upload_screenshotpreview + apply	Upload one rendered image to a screenshot set. The token is bound to the image's MD5.
apple_preview_reorder_screenshotspreview + apply	Set the order shoppers see.
apple_preview_upload_library_assetpreview + apply	Upload to Apple's App Asset Library (API 4.5.1), needed for app previews and iPhone Duo.

Each preview has an apply twin (the same name with apply instead of preview) that only runs with the confirm token from a fresh preview, and refuses if App Store Connect changed in between. MetaRun tools save to your MetaRun workspace only (studio projects, tracked keywords), never to Apple.

07 · Apple rules

What Apple enforces, and how MetaRun handles it

Ten screenshots per display size per language

Apple caps each set at ten. The first three are what most shoppers see in search results, which is why order is its own tool.

Uploads come from https URLs

MetaRun fetches the image from an https URL behind an SSRF guard, checks its size and type from the bytes, and binds the confirm token to the file's MD5.

iPhone Duo needs the App Asset Library

Apple's older screenshot sets have no iPhone Duo display type, and Apple requires Duo screenshots on submissions from April 2027. Duo, app preview videos and creative assets go through the library tools.

Server renders skip the 3D frame

Slides rendered on the server use the 2D device frame. 3D mockups render in the studio in your browser; the tool says so in its notes when it falls back.

08 · Comms

What to ask Codex

Ask Codex: Use the PNGs in fastlane/screenshots/en-US to build a 6-slide screenshot set with the Keynote template. Write captions from our feature list in README.md.
Ask Codex: Render slides 1 to 3 and show me before uploading anything.
Ask Codex: Translate the captions into German and Japanese, check for overflow, then upload the English and German sets.

09 · Unattended

Run it from a script with Codex

codex exec runs one request without an interactive session and with its approval policy set to never. MetaRun's reads and previews still run, because they're marked read-only; anything that would ask is refused.

Read-only check, safe to schedule

codex exec "List the screenshot sets on the editable version of com.example.app, with the count per display size and language. Read only."

Applies are refused in codex exec by design. Don't set MetaRun's approval mode to approve just to make them pass; keep App Store changes in an interactive session.

10 · Safety

How Codex asks before a change

Codex decides per tool from the hints MetaRun sends with each one. In its default mode it runs tools marked read-only, which covers MetaRun's reads and previews, and asks before the rest, which covers every apply. You can change that per server with default_tools_approval_mode, or per tool with tools.<name>.approval_mode in config.toml; keep the apply tools on prompt.

Apple key stays on MetaRun, encryptedPreview before every writeRecorded, revertible from history

11 · FAQ

Frequently asked questions

Can Codex upload screenshots from my machine?

Yes, via an https URL. npx metarun upload <file> returns one for a local PNG or JPEG, and the studio tools take uploads directly. The upload itself runs on MetaRun's servers with your Apple key, which never touches your machine.

Do I have to use MetaRun's studio?

No. If you already have final images, Codex can upload and order them directly with the screenshot tools. The studio is for when you want framing, captions and translations done too.

What sizes does it support?

Every display size Apple lists for screenshot sets, plus the App Asset Library's catalog for newer placements such as iPhone Duo. apple_get_asset_catalog returns Apple's current specs.

Can I see the screenshots before they go up?

Yes. studio_render_slide returns each slide as an image and studio_store_preview shows them in App Store context. Nothing uploads until you approve the apply.

How do I connect Codex to App Store Connect?

Run codex mcp add metarun --url https://metarun.dev/api/mcp; Codex detects MetaRun's sign-in and opens it in your browser. After that, ask for "screenshots" in plain words and Codex picks the MetaRun tools.

Does Codex see my App Store Connect key?

No. Your App Store Connect API key stays envelope-encrypted on MetaRun's servers and is decrypted per request. Codex holds a MetaRun token that you can revoke in Settings at any time.

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