Add GitHub Copilot support (#191)

- OAuth login for GitHub Copilot via /login command
- Support for github.com and GitHub Enterprise
- Models sourced from models.dev (Claude, GPT, Gemini, Grok, etc.)
- Dynamic base URL from token's proxy-ep field
- Use vscode-chat integration ID for API compatibility
- Documentation for model enablement at github.com/settings/copilot/features

Co-authored-by: cau1k <cau1k@users.noreply.github.com>

packages/coding-agent/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## [Unreleased]
 
+### Added
+
+- **GitHub Copilot support**: Use GitHub Copilot models via OAuth login (`/login` -> "GitHub Copilot"). Supports both github.com and GitHub Enterprise. Models are sourced from models.dev and include Claude, GPT, Gemini, Grok, and more. Some models require enablement at https://github.com/settings/copilot/features before use. ([#191](https://github.com/badlogic/pi-mono/pull/191) by [@cau1k](https://github.com/cau1k))
+
 ### Fixed
 
 - Model selector fuzzy search now matches against provider name (not just model ID) and supports space-separated tokens where all tokens must match

packages/coding-agent/README.md

@@ -125,6 +125,23 @@ pi
 /login  # Select "Anthropic (Claude Pro/Max)", authorize in browser
 ```
 
+**GitHub Copilot:**
+
+```bash
+pi
+/login  # Select "GitHub Copilot", authorize in browser
+```
+
+During login, you'll be prompted for an enterprise domain. Press Enter to use github.com, or enter your GitHub Enterprise Server domain (e.g., `github.mycompany.com`).
+
+Some models require explicit enablement before use. If you get "The requested model is not supported" error, enable the model at:
+
+**https://github.com/settings/copilot/features**
+
+For enterprise users, check with your organization's Copilot administrator for model availability and policies.
+
+Note: Enabling some models (e.g., Grok from xAI) may involve sharing usage data with the provider. Review the terms before enabling.
+
 Tokens stored in `~/.pi/agent/oauth.json` (mode 0600). Use `/logout` to clear.
 
 ### Quick Start

packages/coding-agent/src/core/model-config.ts

@@ -242,18 +242,15 @@ export function loadAndMergeModels(): { models: Model<Api>[]; error: string | nu
 
 	const combined = [...builtInModels, ...customModels];
 
+	// Update github-copilot base URL based on OAuth token or enterprise domain
 	const copilotCreds = loadOAuthCredentials("github-copilot");
-	if (copilotCreds?.enterpriseUrl) {
-		const domain = normalizeDomain(copilotCreds.enterpriseUrl);
-		if (domain) {
-			const baseUrl = getGitHubCopilotBaseUrl(domain);
-			return {
-				models: combined.map((m) =>
-					m.provider === "github-copilot" && m.baseUrl === "https://api.githubcopilot.com" ? { ...m, baseUrl } : m,
-				),
-				error: null,
-			};
-		}
+	if (copilotCreds) {
+		const domain = copilotCreds.enterpriseUrl ? normalizeDomain(copilotCreds.enterpriseUrl) : undefined;
+		const baseUrl = getGitHubCopilotBaseUrl(copilotCreds.access, domain ?? undefined);
+		return {
+			models: combined.map((m) => (m.provider === "github-copilot" ? { ...m, baseUrl } : m)),
+			error: null,
+		};
 	}
 
 	return { models: combined, error: null };
@@ -288,23 +285,31 @@ export async function getApiKeyForModel(model: Model<Api>): Promise<string | und
 	}
 
 	if (model.provider === "github-copilot") {
+		// 1. Check OAuth storage (from device flow login)
 		const oauthToken = await getOAuthToken("github-copilot");
 		if (oauthToken) {
 			return oauthToken;
 		}
 
+		// 2. Use GitHub token directly (works with copilot scope on github.com)
 		const githubToken = process.env.COPILOT_GITHUB_TOKEN || process.env.GH_TOKEN || process.env.GITHUB_TOKEN;
 		if (!githubToken) {
 			return undefined;
 		}
 
+		// 3. For enterprise, exchange token for short-lived Copilot token
 		const enterpriseDomain = process.env.COPILOT_ENTERPRISE_URL
 			? normalizeDomain(process.env.COPILOT_ENTERPRISE_URL)
 			: undefined;
 
-		const creds = await refreshGitHubCopilotToken(githubToken, enterpriseDomain || undefined);
-		saveOAuthCredentials("github-copilot", creds);
-		return creds.access;
+		if (enterpriseDomain) {
+			const creds = await refreshGitHubCopilotToken(githubToken, enterpriseDomain);
+			saveOAuthCredentials("github-copilot", creds);
+			return creds.access;
+		}
+
+		// 4. For github.com, use token directly
+		return githubToken;
 	}
 
 	// For built-in providers, use getApiKey from @mariozechner/pi-ai

packages/coding-agent/src/core/oauth/github-copilot.ts

@@ -4,11 +4,9 @@ const CLIENT_ID = "Iv1.b507a08c87ecfe98";
 
 const COPILOT_HEADERS = {
 	"User-Agent": "GitHubCopilotChat/0.35.0",
-	"Editor-Version": "vscode/1.105.1",
+	"Editor-Version": "vscode/1.107.0",
 	"Editor-Plugin-Version": "copilot-chat/0.35.0",
-	"Copilot-Integration-Id": "copilot-developer-cli",
-	"Openai-Intent": "conversation-edits",
-	"X-Initiator": "agent",
+	"Copilot-Integration-Id": "vscode-chat",
 } as const;
 
 type DeviceCodeResponse = {
@@ -54,9 +52,29 @@ function getUrls(domain: string): {
 	};
 }
 
-export function getGitHubCopilotBaseUrl(enterpriseDomain?: string): string {
-	if (!enterpriseDomain) return "https://api.githubcopilot.com";
-	return `https://copilot-api.${enterpriseDomain}`;
+/**
+ * Parse the proxy-ep from a Copilot token and convert to API base URL.
+ * Token format: tid=...;exp=...;proxy-ep=proxy.individual.githubcopilot.com;...
+ * Returns API URL like https://api.individual.githubcopilot.com
+ */
+export function getBaseUrlFromToken(token: string): string | null {
+	const match = token.match(/proxy-ep=([^;]+)/);
+	if (!match) return null;
+	const proxyHost = match[1];
+	// Convert proxy.xxx to api.xxx
+	const apiHost = proxyHost.replace(/^proxy\./, "api.");
+	return `https://${apiHost}`;
+}
+
+export function getGitHubCopilotBaseUrl(token?: string, enterpriseDomain?: string): string {
+	// If we have a token, extract the base URL from proxy-ep
+	if (token) {
+		const urlFromToken = getBaseUrlFromToken(token);
+		if (urlFromToken) return urlFromToken;
+	}
+	// Fallback for enterprise or if token parsing fails
+	if (enterpriseDomain) return `https://copilot-api.${enterpriseDomain}`;
+	return "https://api.individual.githubcopilot.com";
 }
 
 async function fetchJson(url: string, init: RequestInit): Promise<unknown> {