Copilot API (fork)

Fork of ericc-ch/copilot-api — a reverse-engineered proxy that exposes GitHub Copilot as an OpenAI- and Anthropic-compatible API, usable as a backend for Claude Code.

Warning

Reverse-engineered and unsupported by GitHub. Excessive automated/bulk requests may trigger GitHub's abuse detection and get your Copilot access suspended. Use responsibly. See GitHub Acceptable Use and the Copilot Terms.

What this fork adds

• VS Code token bridge / proxy-only auth — obtain the Copilot token from a running VS Code instead of the GitHub device-code flow. Lets the proxy run with no GH_TOKEN (see Token sources).
• Model mappings — MODEL_MAPPINGS env var rewrites incoming model IDs (e.g. the claude-* IDs Claude Code sends) to the internal Copilot model names. This is what makes Claude Code work against Copilot.
• /v1/responses endpoint — OpenAI Responses API support, in addition to the upstream chat/messages/embeddings routes.
• Hardened token refresh — centralized 401 handling, retry with backoff, and survives long-running sessions.
• Enterprise account type by default — bun run dev / bun run auth pass --account-type enterprise.
• Windows .cmd helpers + Claude Code settings.json for a one-double-click workflow (see below).

Prerequisites

• Bun (>= 1.2.x)
• A GitHub account with a Copilot subscription, or a running VS Code signed in to Copilot (for the token bridge)

bun install

Quick start (Windows)

The repo ships .cmd launchers. Set them up once as Windows Terminal profiles (Settings → Add a new profile → New empty profile → paste the script path into Command line), or just double-click them.

Script	What it does
start-copilot-api.cmd	Starts the proxy server (npm run dev) on http://localhost:4141.
start-claude.cmd	Launches Claude Code pointed at the proxy (working dir c:\src\controlplane).
start-cc-copilot-api.cmd	Launches Claude Code in this repo's dir (handy for working on the proxy itself).
re-auth.cmd	Re-runs the GitHub auth flow (npm run auth) when the token expires.

Typical flow: run start-copilot-api.cmd, then start-claude.cmd.

The model IDs and effort level Claude Code uses are set as set ANTHROPIC_* lines at the top of start-claude.cmd / start-cc-copilot-api.cmd — edit those to change models.

Running without the scripts

bun run dev     # watch mode (account-type enterprise)
bun run start   # production
bun run auth    # GitHub auth only

See the upstream README for npx, Docker, and the full CLI option tables — they apply unchanged.

Token sources

The proxy resolves a Copilot token in this order:

1. GitHub token (GH_TOKEN / --github-token, or the interactive device-code flow) → exchanged for a Copilot token, then auto-refreshed.
2. VS Code token bridge (fallback, or proxy-only mode when no GitHub token is present) — the proxy fetches a token from a small VS Code extension at http://127.0.0.1:<VSCODE_PROXY_PORT>/token.

Setting up the VS Code token bridge

Source: wenbo97/copilot-token-bridge — the extension is open source; the bundled .vsix below is a prebuilt copy.

1. Install the bundled extension: copilot-token-bridge-0.3.0.vsix

   code --install-extension copilot-token-bridge-0.3.0.vsix

2. Make sure VS Code is signed in to GitHub Copilot and left running.
3. (Optional) If the extension uses a non-default port, set VSCODE_PROXY_PORT in .env (default 18774).

With the bridge available the proxy can run with no GitHub token at all — useful when the device-code flow is blocked.

Configuration (.env)

Copy .env.example to .env. Fork-relevant keys:

Variable	Purpose	Default
MODEL_MAPPINGS	Rewrite model IDs, source:target comma-separated (e.g. claude-opus-4-8:claude-opus-4.8).	none
VSCODE_PROXY_PORT	Port of the Copilot Token Bridge VS Code extension.	18774
IDLE_TIMEOUT	Bun server idle timeout (seconds).	255
TRACE_OUTPUT_FOLDER	Where request/response traces go when --trace is set.	./traces

MODEL_MAPPINGS example (maps the IDs Claude Code sends to internal Copilot model names):

MODEL_MAPPINGS="claude-opus-4-8:claude-opus-4.8,claude-opus-4-7:claude-opus-4.7-1m-internal,claude-sonnet-4-6:claude-sonnet-4.6,claude-haiku-4-5:claude-haiku-4.5"

Using with the VS Code Claude extension

1. Copy settings.json to C:/Users/<user-name>/.claude/settings.json (create the file if needed).
2. Restart the Claude chat (close and reopen it).

settings.json points ANTHROPIC_BASE_URL at http://localhost:4141 and sets the model IDs — adjust to taste.

Development

Command
bun run dev	Watch-mode server
bun run lint	ESLint (@echristian/eslint-config) — bun run lint --fix to autofix
bun test	Run the test suite (tests/*.test.ts)
bun run typecheck	tsc

See AGENTS.md for code-style conventions.

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Credit: original work by Erick Christian (ko-fi). This fork only layers on the Windows/Claude-Code/token-bridge changes described above.