Copilot API Proxy (Fork)

[!NOTE] This is a fork of @hsupu/copilot-api, which itself is a fork of ericc-ch/copilot-api, with additional improvements and bug fixes.

[!WARNING] This is a reverse-engineered proxy of GitHub Copilot API. It is not supported by GitHub, and may break unexpectedly. Use at your own risk.

New Features (over @hsupu/copilot-api)

• Responses API endpoint: /v1/responses passthrough for codex models (e.g., gpt-5.2-codex, gpt-5.3-codex) used by tools like OpenCode. Includes stream ID synchronization for @ai-sdk/openai compatibility.
• SubagentStart marker support: Detects __SUBAGENT_MARKER__ injected by Claude Code hooks to override X-Initiator header to "agent" for subagent requests, ensuring correct credit tier usage. Includes a ready-to-use Claude plugin (claude-plugin/).
• Token analytics tab: The /history page includes a Tokens tab with per-model token usage summary table and cumulative ECharts line chart for visualizing API consumption over time.
• Real-time history updates: The /history UI uses WebSocket for live updates instead of polling, with automatic fallback to polling and exponential backoff reconnection.
• Graceful shutdown: 4-phase shutdown sequence — stops accepting requests, waits for in-flight requests to complete, sends abort signal, then force-closes. Configurable via --shutdown-graceful-wait and --shutdown-abort-wait.
• Stream repetition detection: Detects when models get stuck in repetitive output loops using KMP-based pattern matching and logs a warning.
• Stale request reaping: Automatically force-fails requests that exceed a configurable maximum age (default 600s) to prevent resource leaks.
• Gemini API compatibility: /v1beta/models endpoints translate Gemini API requests to OpenAI format for Copilot. Enables Google Gemini CLI to use Copilot models via GOOGLE_GEMINI_BASE_URL environment variable.
• PostHog analytics: Optional PostHog Cloud integration (--posthog-key) sends per-request token usage events for long-term trend analysis. Free tier (1M events/month) is more than sufficient for individual use.

Quick Start

Install from npm (Recommended)

# Run directly with npx
npx @dianshuv/copilot-api start

# Or install globally
npm install -g @dianshuv/copilot-api
copilot-api start

Development

# Start the server (foreground, production mode)
make up

# Stop the server (graceful shutdown)
make down

Command Reference

| Command | Description | |---------|-------------| | start | Start the API server (handles auth if needed) | | auth | Run GitHub authentication flow only | | logout | Remove stored GitHub token | | check-usage | Show Copilot usage and quota | | debug | Display diagnostic information | | patch-claude | Patch Claude Code's context window limit |

Start Command Options

| Option | Description | Default | |--------|-------------|---------| | --port, -p | Port to listen on | 4141 | | --host, -H | Host/interface to bind to | (all interfaces) | | --verbose, -v | Enable verbose logging | false | | --account-type, -a | Account type (individual, business, enterprise) | individual | | --manual | Manual request approval mode | false | | --no-rate-limit | Disable adaptive rate limiting | false | | --retry-interval | Seconds to wait before retrying after rate limit | 10 | | --request-interval | Seconds between requests in rate-limited mode | 10 | | --recovery-timeout | Minutes before attempting recovery | 10 | | --consecutive-successes | Successes needed to exit rate-limited mode | 5 | | --github-token, -g | Provide GitHub token directly | none | | --claude-code, -c | Generate Claude Code launch command | false | | --show-token | Show tokens on fetch/refresh | false | | --proxy-env | Use proxy from environment | false | | --no-history | Disable request history UI at /history | false | | --history-limit | Max history entries in memory | 1000 | | --no-auto-truncate | Disable auto-truncate when exceeding token limits | false | | --compress-tool-results | Compress old tool results before truncating | false | | --redirect-anthropic | Force Anthropic through OpenAI translation | false | | --strip-server-tools | Strip server-side tools from Anthropic requests | false | | --context-editing | Context editing mode: off, clear-thinking, clear-tooluse, clear-both | off | | --timezone-offset | Timezone offset in hours from UTC for log timestamps (e.g., +8, -5, 0) | +8 | | --posthog-key | PostHog API key for token usage analytics (opt-in) | none |

Patch-Claude Command Options

| Option | Description | Default | |--------|-------------|---------| | --limit, -l | Context window limit in tokens | 128000 | | --restore, -r | Restore original 200k limit | false | | --path, -p | Path to Claude Code cli.js | auto-detect | | --status, -s | Show current patch status | false |

API Endpoints

OpenAI Compatible

| Endpoint | Method | Description | |----------|--------|-------------| | /v1/chat/completions | POST | Chat completions | | /v1/models | GET | List available models | | /v1/embeddings | POST | Text embeddings | | /v1/responses | POST | Responses API (for codex models) |

Anthropic Compatible

| Endpoint | Method | Description | |----------|--------|-------------| | /v1/messages | POST | Messages API | | /v1/messages/count_tokens | POST | Token counting | | /v1/event_logging/batch | POST | Event logging (no-op) |

Gemini Compatible

| Endpoint | Method | Description | |----------|--------|-------------| | /v1beta/models/{model}:generateContent | POST | Non-streaming generation | | /v1beta/models/{model}:streamGenerateContent | POST | Streaming generation (SSE) | | /v1beta/models/{model}:countTokens | POST | Token counting |

Utility

| Endpoint | Method | Description | |----------|--------|-------------| | / | GET | Server status | | /usage | GET | Copilot usage stats | | /token | GET | Current Copilot token | | /health | GET | Health check | | /history | GET | Request history Web UI with token analytics (enabled by default) | | /history/api/* | GET/DELETE | History API endpoints |

Auto-Truncate

When enabled (default), auto-truncate automatically compacts conversation history when it exceeds the model's token limit. This prevents request failures due to context overflow.

• Token-based truncation: Uses the model's max_context_window_tokens from the Copilot API to determine when truncation is needed. A 2% safety margin is applied.
• No preset byte limit: There is no hardcoded request body size limit. If the Copilot API returns a 413 (Request Entity Too Large), the proxy dynamically learns the byte limit and applies it to subsequent requests.
• Smart compression: With --compress-tool-results, old tool results are compressed before removing messages, preserving more conversation context.
• Orphan filtering: After truncation, orphaned tool results (without matching tool calls) are automatically removed.

Using with Claude Code

Create .claude/settings.json in your project:

{
  "env": {
    "ANTHROPIC_BASE_URL": "http://localhost:4141",
    "ANTHROPIC_AUTH_TOKEN": "dummy",
    "ANTHROPIC_MODEL": "gpt-4.1",
    "ANTHROPIC_SMALL_FAST_MODEL": "gpt-4.1",
    "DISABLE_NON_ESSENTIAL_MODEL_CALLS": "1",
    "CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC": "1"
  },
  "permissions": {
    "deny": ["WebSearch"]
  }
}

Or use the interactive setup:

bun run start --claude-code

Using with Gemini CLI

# Start the proxy
copilot-api start

# Configure Gemini CLI to use the proxy
export GEMINI_API_KEY="placeholder"
export GOOGLE_GEMINI_BASE_URL="http://localhost:4141"

# Basic conversation
gemini -p "Explain this code"

# Pipe review
git diff HEAD~1 | gemini -p "Review this diff for bugs"

Upstream Project

For the original project documentation, features, and updates, see: ericc-ch/copilot-api