Docs

Get started with StudioCat

StudioCat connects ChatGPT on the web to projects on your Mac. ChatGPT decides what to do; StudioCat runs it locally, checks every call against the permissions you set, and shows every change in its workbench.

Requirements

• A Mac with macOS 14 or later.
• A ChatGPT account that can use developer mode on the web. ChatGPT on iPhone, iPad and Android can't call custom MCP servers yet.
• An OpenAI Platform organization where you can create a tunnel and an API key. This involves no model API billing.
• The toolchains your projects already use (Go, Swift, Node, …). StudioCat runs them; it doesn't bundle them.

Install

Download the signed and notarized DMG, open it, and drag StudioCat to Applications. StudioCat updates itself; you'll be asked before an update is installed. During the private beta, request access from the home page.

On first launch, the setup assistant walks you through the next three steps. You can reopen it any time from the tunnel status in the top bar or StudioCat → Setup Assistant….

1 · Create a tunnel

1. Open Platform → Tunnels and create a tunnel. Copy its Tunnel ID (tunnel_…).
2. Open Platform → API keys and create a key. Choose Restricted and enable only Tunnels: Read and Use.
3. If your account belongs to several organizations (for example a personal one and a work one), note the ID of the organization that owns the tunnel (org-…, under Settings → Organization).

2 · Connect StudioCat

Paste the Tunnel ID, the API key and, if needed, the organization ID into the setup assistant (or Settings → General → Tunnel Credentials) and choose Save and connect. The credentials go into your macOS Keychain. The tunnel status in the top bar turns green when StudioCat is connected. Your Mac only makes outbound HTTPS connections — StudioCat never opens a port.

3 · Add the MCP server in ChatGPT

1. In a desktop browser, open chatgpt.com/plugins. If you don't see a way to add one, turn on developer mode in ChatGPT's advanced settings first.
2. Add an MCP server named StudioCat. For Connection, choose Tunnel and select your tunnel (or paste the Tunnel ID).
3. Save, refresh, and start a new chat with StudioCat enabled. Try: “Use StudioCat to list the files at the root of my project.”

If you later switch to a different tunnel, point the MCP server in ChatGPT at the new tunnel too — otherwise calls report that the tunnel client isn't connected.

Projects & permissions

StudioCat only works inside projects you open with File → Open Workspace… (⌘O). When you open a project you decide what it may do:

• Read, search, edit, patch, checkpoints and code intelligence are allowed by default inside the project.
• Terminal (running commands) and Commits are off by default. Turn them on per project — or approve them when ChatGPT first asks.
• Commands that match a dangerous pattern ask for your confirmation on the Mac. Denying is final; nothing runs.

There are two confirmations by design: ChatGPT may ask whether to send a call, and StudioCat may ask before running a risky one. Neither replaces the other.

Review & roll back

• The Activity view shows each call as it happens; Output shows command output.
• Every edit lands as a card in Review Diff. Roll Back restores the files, including renames and file modes. If a file changed again afterwards, the older card refuses rather than overwriting your newer edit.
• Checkpoints snapshot the project in hidden git refs; your branch, HEAD, index and stash are never touched.

Checkpoints are not backups. Files deleted with rm -rf in the terminal that git ignores (like build/) can't be recovered.

Several projects at once

Each ChatGPT conversation is bound to the project it first worked in. You can switch what the workbench shows; the conversation keeps working in its own project in the background. Opening another project from a conversation (with an explicit path) moves that conversation.

Troubleshooting

“API key is invalid”

Copy the whole key again, or create a new one. Revoked keys stop working immediately.

“This key can't use the tunnel” (tunnel_use_forbidden)

Give the key Tunnels Read and Use. New permissions can take a few minutes.

“Organization ID needed” (tunnel_active_organization_required)

Your key belongs to several organizations. Enter the tunnel's organization ID in Settings and reconnect.

ChatGPT says the tunnel client isn't connected

Check that the top bar shows the tunnel as connected, and that the MCP server in ChatGPT uses the same tunnel as StudioCat.

It works on the web but not on my phone

Expected: ChatGPT's mobile apps can't call custom MCP servers yet.

Can't reach OpenAI

Check your network. If you use a proxy, make sure the system proxy is on; StudioCat follows it and retries on its own.

Data & uninstall

• Settings, permissions, logs and the local audit log live in ~/.cache/StudioCat/.
• Tunnel credentials live in the Keychain item StudioCat.mcp-tunnel. Settings → Remove deletes it.
• To uninstall, quit StudioCat, move it to the Trash, and delete ~/.cache/StudioCat/. Remove the MCP server in ChatGPT and revoke the API key in Platform.