ChampCity GPT MCP Launcher

ChampCity GPT MCP Launcher is a pre-release ChatGPT-compatible MCP server and Electron launcher for controlled local project-file access. It can expose read-only and approval-gated write tools over local STDIO or local HTTP, with optional OAuth and HTTPS tunneling for ChatGPT.com-compatible MCP connectors.

Current maturity: v0.1.0, pre-release/private-tooling quality. Review the code and security model before using it with sensitive repositories.

License: not yet selected. See docs/LICENSE_DECISION_NEEDED.md.

What It Does

• Lists, reads, and searches files inside configured allowed roots.

• Reports git status and git diffs for allowed git worktrees.

• Supports write modes: off, docs, patch, and elevated.

• Provides an Electron launcher for local setup, status checks, OAuth administration, and client config generation.

• Supports local STDIO MCP for trusted local clients.

• Supports local Streamable HTTP MCP on 127.0.0.1.

• Supports OAuth metadata, Dynamic Client Registration, PKCE, access tokens, refresh token rotation, and scopes for ChatGPT.com-compatible public HTTPS endpoints.

• Includes optional Cloudflare Tunnel docs and examples.

Related MCP server: chatgpt-codex-local-mcp

What It Does Not Do

• It does not make hosted ChatGPT local-only; file contents returned by tools can enter the model/tool context.

• It does not safely expose arbitrary folders. You must configure narrow allowed roots.

• It does not require Cloudflare or any specific domain. https://mcp.example.com/mcp is only a placeholder.

• It does not enable writes by default.

• It does not replace human review. Review generated patches and git diffs before committing.

Security Model

Filesystem access is limited to configured allowed roots. Use project-level roots such as:

C:\Users\<you>\Projects\<project>

Avoid broad roots such as C:\, C:\Users\<you>, home directories, cloud sync roots, browser profile folders, SSH folders, and credential stores.

HTTP mode should bind to 127.0.0.1 by default. ChatGPT.com compatibility requires an HTTPS-reachable endpoint with OAuth and Dynamic Client Registration. For public use, set:

CHAMPCITY_GPT_PUBLIC_BASE_URL=https://mcp.example.com

OAuth scopes:

• files.read: list/read/search files, git status/diff, write-access status, and tool discovery.

• files.write: propose patches, write Markdown artifacts, apply approved patches, and run allowlisted scripts, still gated by local write mode.

Never expose unauthenticated HTTP mode through a tunnel.

Write Modes

• off: default. Blocks write tools.

• docs: allows Markdown artifact writes for planning or notes.

• patch: allows proposed patch workflows and approved patch application.

• elevated: allows rare allowlisted script/elevated operations with a local approval token.

Set the mode with:

$env:CHAMPCITY_GPT_WRITE_MODE='off'

Local Configuration

On first launch, the Electron app opens a setup wizard where each user chooses allowed roots, local-only or public endpoint mode, OAuth admin password, optional Cloudflare guidance, and write mode. Write mode defaults to off, and the OAuth admin password is stored only as a local hash.

For source development, you can still copy example config files and create repo-local versions as needed:

Copy-Item config\allowed-roots.example.json config\allowed-roots.local.json
Copy-Item config\write-access.example.json config\write-access.local.json

Local files matching config/*.local.json are ignored by git. Do not commit OAuth stores, auth tokens, local paths, tunnel credentials, logs, generated configs, release outputs, or .env files.

Useful examples:

• config/allowed-roots.example.json

• config/write-access.example.json

• config/http-auth.example.json

• config/oauth.example.json

• examples/cloudflared-config.example.yml

• examples/mcp-client-config.example.json

Development

Requirements:

• Node.js >=20.10.0

• npm

Install, build, and test:

npm install
npm run build
npm test
npm run typecheck
npm run lint

Public clone/build flow:

git clone https://github.com/<owner>/<repo>.git
cd <repo>
npm install
npm run build
npm test
npm run app:dist

Run the local MCP server after building:

node dist\src\index.js

Run the Electron app:

npm run app:dev

Package the Electron app:

npm run app:dist

Release binaries belong in GitHub Releases, not in the repository.

Runtime Paths

Development mode uses the source checkout and can use repo-local config/*.local.json for development.

Installed mode stores runtime-local files under Electron userData:

• config

• logs

• generated

Portable mode activates when a data folder exists next to the executable:

• <exeDir>\data\config

• <exeDir>\data\logs

• <exeDir>\data\generated

The app status panel shows runtime mode, config directory, logs directory, generated directory, and bundled server resource path.

ChatGPT-Compatible HTTPS Endpoint

For ChatGPT.com-compatible MCP registration, use an HTTPS endpoint like:

https://mcp.example.com/mcp

The server exposes OAuth metadata under:

https://mcp.example.com/.well-known/oauth-protected-resource
https://mcp.example.com/.well-known/oauth-authorization-server
https://mcp.example.com/oauth/register
https://mcp.example.com/oauth/authorize
https://mcp.example.com/oauth/token

Cloudflare Tunnel is optional. Any equivalent HTTPS reverse tunnel can work if OAuth remains enabled and the local service is still bound narrowly.

Publication Safety

Before publishing, run the release and publication checklists:

• docs/RELEASE_CHECKLIST.md

• docs/GITHUB_PUBLICATION_CHECKLIST.md

• docs/PUBLICATION_AUDIT.md

Do not publish until the license, GitHub owner/repo, and release-binary policy are decided.

Final local checks:

npm run check:public
npm run app:dist
npm run check:release