refactor(oauth): add provider registry

2026-04-16 14:01:06 +00:00 · 2026-01-24 21:17:05 +01:00 · 2026-01-24 21:17:05 +01:00 · 3256d3c083
commit 3256d3c083
parent 89636cfe6e
19 changed files with 655 additions and 291 deletions
--- a/packages/ai/src/cli.ts
+++ b/packages/ai/src/cli.ts
@ -2,13 +2,8 @@

 import { existsSync, readFileSync, writeFileSync } from "fs";
 import { createInterface } from "readline";
-import { loginAnthropic } from "./utils/oauth/anthropic.js";
-import { loginGitHubCopilot } from "./utils/oauth/github-copilot.js";
-import { loginAntigravity } from "./utils/oauth/google-antigravity.js";
-import { loginGeminiCli } from "./utils/oauth/google-gemini-cli.js";
-import { getOAuthProviders } from "./utils/oauth/index.js";
-import { loginOpenAICodex } from "./utils/oauth/openai-codex.js";
-import type { OAuthCredentials, OAuthProvider } from "./utils/oauth/types.js";
+import { getOAuthProvider, getOAuthProviders } from "./utils/oauth/index.js";
+import type { OAuthCredentials, OAuthProviderId } from "./utils/oauth/types.js";

 const AUTH_FILE = "auth.json";
 const PROVIDERS = getOAuthProviders();
@ -30,78 +25,31 @@ function saveAuth(auth: Record<string, { type: "oauth" } & OAuthCredentials>): v
 	writeFileSync(AUTH_FILE, JSON.stringify(auth, null, 2), "utf-8");
 }

-async function login(provider: OAuthProvider): Promise<void> {
-	const rl = createInterface({ input: process.stdin, output: process.stdout });
+async function login(providerId: OAuthProviderId): Promise<void> {
+	const provider = getOAuthProvider(providerId);
+	if (!provider) {
+		console.error(`Unknown provider: ${providerId}`);
+		process.exit(1);
+	}

+	const rl = createInterface({ input: process.stdin, output: process.stdout });
 	const promptFn = (msg: string) => prompt(rl, `${msg} `);

 	try {
-		let credentials: OAuthCredentials;
-
-		switch (provider) {
-			case "anthropic":
-				credentials = await loginAnthropic(
-					(url) => {
-						console.log(`\nOpen this URL in your browser:\n${url}\n`);
-					},
-					async () => {
-						return await promptFn("Paste the authorization code:");
-					},
-				);
-				break;
-
-			case "github-copilot":
-				credentials = await loginGitHubCopilot({
-					onAuth: (url, instructions) => {
-						console.log(`\nOpen this URL in your browser:\n${url}`);
-						if (instructions) console.log(instructions);
-						console.log();
-					},
-					onPrompt: async (p) => {
-						return await promptFn(`${p.message}${p.placeholder ? ` (${p.placeholder})` : ""}:`);
-					},
-					onProgress: (msg) => console.log(msg),
-				});
-				break;
-
-			case "google-gemini-cli":
-				credentials = await loginGeminiCli(
-					(info) => {
-						console.log(`\nOpen this URL in your browser:\n${info.url}`);
-						if (info.instructions) console.log(info.instructions);
-						console.log();
-					},
-					(msg) => console.log(msg),
-				);
-				break;
-
-			case "google-antigravity":
-				credentials = await loginAntigravity(
-					(info) => {
-						console.log(`\nOpen this URL in your browser:\n${info.url}`);
-						if (info.instructions) console.log(info.instructions);
-						console.log();
-					},
-					(msg) => console.log(msg),
-				);
-				break;
-			case "openai-codex":
-				credentials = await loginOpenAICodex({
-					onAuth: (info) => {
-						console.log(`\nOpen this URL in your browser:\n${info.url}`);
-						if (info.instructions) console.log(info.instructions);
-						console.log();
-					},
-					onPrompt: async (p) => {
-						return await promptFn(`${p.message}${p.placeholder ? ` (${p.placeholder})` : ""}:`);
-					},
-					onProgress: (msg) => console.log(msg),
-				});
-				break;
-		}
+		const credentials = await provider.login({
+			onAuth: (info) => {
+				console.log(`\nOpen this URL in your browser:\n${info.url}`);
+				if (info.instructions) console.log(info.instructions);
+				console.log();
+			},
+			onPrompt: async (p) => {
+				return await promptFn(`${p.message}${p.placeholder ? ` (${p.placeholder})` : ""}:`);
+			},
+			onProgress: (msg) => console.log(msg),
+		});

 		const auth = loadAuth();
-		auth[provider] = { type: "oauth", ...credentials };
+		auth[providerId] = { type: "oauth", ...credentials };
 		saveAuth(auth);

 		console.log(`\nCredentials saved to ${AUTH_FILE}`);
@ -115,6 +63,7 @@ async function main(): Promise<void> {
 	const command = args[0];

 	if (!command || command === "help" || command === "--help" || command === "-h") {
+		const providerList = PROVIDERS.map((p) => `  ${p.id.padEnd(20)} ${p.name}`).join("\n");
 		console.log(`Usage: npx @mariozechner/pi-ai <command> [provider]

 Commands:
@ -122,11 +71,7 @@ Commands:
  list              List available providers

 Providers:
-  anthropic         Anthropic (Claude Pro/Max)
-  github-copilot    GitHub Copilot
-  google-gemini-cli Google Gemini CLI
-  google-antigravity Antigravity (Gemini 3, Claude, GPT-OSS)
-  openai-codex      OpenAI Codex (ChatGPT Plus/Pro)
+${providerList}

 Examples:
  npx @mariozechner/pi-ai login              # interactive provider selection
@ -145,7 +90,7 @@ Examples:
 	}

 	if (command === "login") {
-		let provider = args[1] as OAuthProvider | undefined;
+		let provider = args[1] as OAuthProviderId | undefined;

 		if (!provider) {
 			const rl = createInterface({ input: process.stdin, output: process.stdout });
--- a/packages/ai/src/utils/oauth/anthropic.ts
+++ b/packages/ai/src/utils/oauth/anthropic.ts
@ -3,7 +3,7 @@
 */

 import { generatePKCE } from "./pkce.js";
-import type { OAuthCredentials } from "./types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthProviderInterface } from "./types.js";

 const decode = (s: string) => atob(s);
 const CLIENT_ID = decode("OWQxYzI1MGEtZTYxYi00NGQ5LTg4ZWQtNTk0NGQxOTYyZjVl");
@ -116,3 +116,23 @@ export async function refreshAnthropicToken(refreshToken: string): Promise<OAuth
 		expires: Date.now() + data.expires_in * 1000 - 5 * 60 * 1000,
 	};
 }
+
+export const anthropicOAuthProvider: OAuthProviderInterface = {
+	id: "anthropic",
+	name: "Anthropic (Claude Pro/Max)",
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginAnthropic(
+			(url) => callbacks.onAuth({ url }),
+			() => callbacks.onPrompt({ message: "Paste the authorization code:" }),
+		);
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		return refreshAnthropicToken(credentials.refresh);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		return credentials.access;
+	},
+};
--- a/packages/ai/src/utils/oauth/github-copilot.ts
+++ b/packages/ai/src/utils/oauth/github-copilot.ts
@ -3,7 +3,12 @@
 */

 import { getModels } from "../../models.js";
-import type { OAuthCredentials } from "./types.js";
+import type { Api, Model } from "../../types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthProviderInterface } from "./types.js";
+
+type CopilotCredentials = OAuthCredentials & {
+	enterpriseUrl?: string;
+};

 const decode = (s: string) => atob(s);
 const CLIENT_ID = decode("SXYxLmI1MDdhMDhjODdlY2ZlOTg=");
@ -344,3 +349,33 @@ export async function loginGitHubCopilot(options: {
 	await enableAllGitHubCopilotModels(credentials.access, enterpriseDomain ?? undefined);
 	return credentials;
 }
+
+export const githubCopilotOAuthProvider: OAuthProviderInterface = {
+	id: "github-copilot",
+	name: "GitHub Copilot",
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginGitHubCopilot({
+			onAuth: (url, instructions) => callbacks.onAuth({ url, instructions }),
+			onPrompt: callbacks.onPrompt,
+			onProgress: callbacks.onProgress,
+			signal: callbacks.signal,
+		});
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		const creds = credentials as CopilotCredentials;
+		return refreshGitHubCopilotToken(creds.refresh, creds.enterpriseUrl);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		return credentials.access;
+	},
+
+	modifyModels(models: Model<Api>[], credentials: OAuthCredentials): Model<Api>[] {
+		const creds = credentials as CopilotCredentials;
+		const domain = creds.enterpriseUrl ? (normalizeDomain(creds.enterpriseUrl) ?? undefined) : undefined;
+		const baseUrl = getGitHubCopilotBaseUrl(creds.access, domain);
+		return models.map((m) => (m.provider === "github-copilot" ? { ...m, baseUrl } : m));
+	},
+};
--- a/packages/ai/src/utils/oauth/google-antigravity.ts
+++ b/packages/ai/src/utils/oauth/google-antigravity.ts
@ -8,7 +8,11 @@

 import type { Server } from "http";
 import { generatePKCE } from "./pkce.js";
-import type { OAuthCredentials } from "./types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthProviderInterface } from "./types.js";
+
+type AntigravityCredentials = OAuthCredentials & {
+	projectId: string;
+};

 // Antigravity OAuth credentials (different from Gemini CLI)
 const decode = (s: string) => atob(s);
@ -411,3 +415,26 @@ export async function loginAntigravity(
 		server.server.close();
 	}
 }
+
+export const antigravityOAuthProvider: OAuthProviderInterface = {
+	id: "google-antigravity",
+	name: "Antigravity (Gemini 3, Claude, GPT-OSS)",
+	usesCallbackServer: true,
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginAntigravity(callbacks.onAuth, callbacks.onProgress, callbacks.onManualCodeInput);
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		const creds = credentials as AntigravityCredentials;
+		if (!creds.projectId) {
+			throw new Error("Antigravity credentials missing projectId");
+		}
+		return refreshAntigravityToken(creds.refresh, creds.projectId);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		const creds = credentials as AntigravityCredentials;
+		return JSON.stringify({ token: creds.access, projectId: creds.projectId });
+	},
+};
--- a/packages/ai/src/utils/oauth/google-gemini-cli.ts
+++ b/packages/ai/src/utils/oauth/google-gemini-cli.ts
@ -8,7 +8,11 @@

 import type { Server } from "http";
 import { generatePKCE } from "./pkce.js";
-import type { OAuthCredentials } from "./types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthProviderInterface } from "./types.js";
+
+type GeminiCredentials = OAuthCredentials & {
+	projectId: string;
+};

 const decode = (s: string) => atob(s);
 const CLIENT_ID = decode(
@ -553,3 +557,26 @@ export async function loginGeminiCli(
 		server.server.close();
 	}
 }
+
+export const geminiCliOAuthProvider: OAuthProviderInterface = {
+	id: "google-gemini-cli",
+	name: "Google Cloud Code Assist (Gemini CLI)",
+	usesCallbackServer: true,
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginGeminiCli(callbacks.onAuth, callbacks.onProgress, callbacks.onManualCodeInput);
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		const creds = credentials as GeminiCredentials;
+		if (!creds.projectId) {
+			throw new Error("Google Cloud credentials missing projectId");
+		}
+		return refreshGoogleCloudToken(creds.refresh, creds.projectId);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		const creds = credentials as GeminiCredentials;
+		return JSON.stringify({ token: creds.access, projectId: creds.projectId });
+	},
+};
--- a/packages/ai/src/utils/oauth/index.ts
+++ b/packages/ai/src/utils/oauth/index.ts
@ -10,100 +10,111 @@
 */

 // Anthropic
-export { loginAnthropic, refreshAnthropicToken } from "./anthropic.js";
+export { anthropicOAuthProvider, loginAnthropic, refreshAnthropicToken } from "./anthropic.js";
 // GitHub Copilot
 export {
 	getGitHubCopilotBaseUrl,
+	githubCopilotOAuthProvider,
 	loginGitHubCopilot,
 	normalizeDomain,
 	refreshGitHubCopilotToken,
 } from "./github-copilot.js";
 // Google Antigravity
-export {
-	loginAntigravity,
-	refreshAntigravityToken,
-} from "./google-antigravity.js";
+export { antigravityOAuthProvider, loginAntigravity, refreshAntigravityToken } from "./google-antigravity.js";
 // Google Gemini CLI
-export {
-	loginGeminiCli,
-	refreshGoogleCloudToken,
-} from "./google-gemini-cli.js";
+export { geminiCliOAuthProvider, loginGeminiCli, refreshGoogleCloudToken } from "./google-gemini-cli.js";
 // OpenAI Codex (ChatGPT OAuth)
-export {
-	loginOpenAICodex,
-	refreshOpenAICodexToken,
-} from "./openai-codex.js";
+export { loginOpenAICodex, openaiCodexOAuthProvider, refreshOpenAICodexToken } from "./openai-codex.js";

 export * from "./types.js";

 // ============================================================================
-// High-level API
+// Provider Registry
 // ============================================================================

-import { refreshAnthropicToken } from "./anthropic.js";
-import { refreshGitHubCopilotToken } from "./github-copilot.js";
-import { refreshAntigravityToken } from "./google-antigravity.js";
-import { refreshGoogleCloudToken } from "./google-gemini-cli.js";
-import { refreshOpenAICodexToken } from "./openai-codex.js";
-import type { OAuthCredentials, OAuthProvider, OAuthProviderInfo } from "./types.js";
+import { anthropicOAuthProvider } from "./anthropic.js";
+import { githubCopilotOAuthProvider } from "./github-copilot.js";
+import { antigravityOAuthProvider } from "./google-antigravity.js";
+import { geminiCliOAuthProvider } from "./google-gemini-cli.js";
+import { openaiCodexOAuthProvider } from "./openai-codex.js";
+import type { OAuthCredentials, OAuthProviderId, OAuthProviderInfo, OAuthProviderInterface } from "./types.js";
+
+const oauthProviderRegistry = new Map<string, OAuthProviderInterface>([
+	[anthropicOAuthProvider.id, anthropicOAuthProvider],
+	[githubCopilotOAuthProvider.id, githubCopilotOAuthProvider],
+	[geminiCliOAuthProvider.id, geminiCliOAuthProvider],
+	[antigravityOAuthProvider.id, antigravityOAuthProvider],
+	[openaiCodexOAuthProvider.id, openaiCodexOAuthProvider],
+]);
+
+/**
+ * Get an OAuth provider by ID
+ */
+export function getOAuthProvider(id: OAuthProviderId): OAuthProviderInterface | undefined {
+	return oauthProviderRegistry.get(id);
+}
+
+/**
+ * Register a custom OAuth provider
+ */
+export function registerOAuthProvider(provider: OAuthProviderInterface): void {
+	oauthProviderRegistry.set(provider.id, provider);
+}
+
+/**
+ * Get all registered OAuth providers
+ */
+export function getOAuthProviders(): OAuthProviderInterface[] {
+	return Array.from(oauthProviderRegistry.values());
+}
+
+/**
+ * @deprecated Use getOAuthProviders() which returns OAuthProviderInterface[]
+ */
+export function getOAuthProviderInfoList(): OAuthProviderInfo[] {
+	return getOAuthProviders().map((p) => ({
+		id: p.id,
+		name: p.name,
+		available: true,
+	}));
+}
+
+// ============================================================================
+// High-level API (uses provider registry)
+// ============================================================================

 /**
 * Refresh token for any OAuth provider.
- * Saves the new credentials and returns the new access token.
+ * @deprecated Use getOAuthProvider(id).refreshToken() instead
 */
 export async function refreshOAuthToken(
-	provider: OAuthProvider,
+	providerId: OAuthProviderId,
 	credentials: OAuthCredentials,
 ): Promise<OAuthCredentials> {
-	if (!credentials) {
-		throw new Error(`No OAuth credentials found for ${provider}`);
+	const provider = getOAuthProvider(providerId);
+	if (!provider) {
+		throw new Error(`Unknown OAuth provider: ${providerId}`);
 	}
-
-	let newCredentials: OAuthCredentials;
-
-	switch (provider) {
-		case "anthropic":
-			newCredentials = await refreshAnthropicToken(credentials.refresh);
-			break;
-		case "github-copilot":
-			newCredentials = await refreshGitHubCopilotToken(credentials.refresh, credentials.enterpriseUrl);
-			break;
-		case "google-gemini-cli":
-			if (!credentials.projectId) {
-				throw new Error("Google Cloud credentials missing projectId");
-			}
-			newCredentials = await refreshGoogleCloudToken(credentials.refresh, credentials.projectId);
-			break;
-		case "google-antigravity":
-			if (!credentials.projectId) {
-				throw new Error("Antigravity credentials missing projectId");
-			}
-			newCredentials = await refreshAntigravityToken(credentials.refresh, credentials.projectId);
-			break;
-		case "openai-codex":
-			newCredentials = await refreshOpenAICodexToken(credentials.refresh);
-			break;
-		default:
-			throw new Error(`Unknown OAuth provider: ${provider}`);
-	}
-
-	return newCredentials;
+	return provider.refreshToken(credentials);
 }

 /**
 * Get API key for a provider from OAuth credentials.
 * Automatically refreshes expired tokens.
 *
- * For google-gemini-cli and antigravity, returns JSON-encoded { token, projectId }
- *
- * @returns API key string, or null if no credentials
+ * @returns API key string and updated credentials, or null if no credentials
 * @throws Error if refresh fails
 */
 export async function getOAuthApiKey(
-	provider: OAuthProvider,
+	providerId: OAuthProviderId,
 	credentials: Record<string, OAuthCredentials>,
 ): Promise<{ newCredentials: OAuthCredentials; apiKey: string } | null> {
-	let creds = credentials[provider];
+	const provider = getOAuthProvider(providerId);
+	if (!provider) {
+		throw new Error(`Unknown OAuth provider: ${providerId}`);
+	}
+
+	let creds = credentials[providerId];
 	if (!creds) {
 		return null;
 	}
@ -111,47 +122,12 @@ export async function getOAuthApiKey(
 	// Refresh if expired
 	if (Date.now() >= creds.expires) {
 		try {
-			creds = await refreshOAuthToken(provider, creds);
+			creds = await provider.refreshToken(creds);
 		} catch (_error) {
-			throw new Error(`Failed to refresh OAuth token for ${provider}`);
+			throw new Error(`Failed to refresh OAuth token for ${providerId}`);
 		}
 	}

-	// For providers that need projectId, return JSON
-	const needsProjectId = provider === "google-gemini-cli" || provider === "google-antigravity";
-	const apiKey = needsProjectId ? JSON.stringify({ token: creds.access, projectId: creds.projectId }) : creds.access;
+	const apiKey = provider.getApiKey(creds);
 	return { newCredentials: creds, apiKey };
 }
-
-/**
- * Get list of OAuth providers
- */
-export function getOAuthProviders(): OAuthProviderInfo[] {
-	return [
-		{
-			id: "anthropic",
-			name: "Anthropic (Claude Pro/Max)",
-			available: true,
-		},
-		{
-			id: "openai-codex",
-			name: "ChatGPT Plus/Pro (Codex Subscription)",
-			available: true,
-		},
-		{
-			id: "github-copilot",
-			name: "GitHub Copilot",
-			available: true,
-		},
-		{
-			id: "google-gemini-cli",
-			name: "Google Cloud Code Assist (Gemini CLI)",
-			available: true,
-		},
-		{
-			id: "google-antigravity",
-			name: "Antigravity (Gemini 3, Claude, GPT-OSS)",
-			available: true,
-		},
-	];
-}
--- a/packages/ai/src/utils/oauth/openai-codex.ts
+++ b/packages/ai/src/utils/oauth/openai-codex.ts
@ -18,7 +18,7 @@ if (typeof process !== "undefined" && (process.versions?.node || process.version
 }

 import { generatePKCE } from "./pkce.js";
-import type { OAuthCredentials, OAuthPrompt } from "./types.js";
+import type { OAuthCredentials, OAuthLoginCallbacks, OAuthPrompt, OAuthProviderInterface } from "./types.js";

 const CLIENT_ID = "app_EMoamEEZ73f0CkXaXp7hrann";
 const AUTHORIZE_URL = "https://auth.openai.com/oauth/authorize";
@ -430,3 +430,26 @@ export async function refreshOpenAICodexToken(refreshToken: string): Promise<OAu
 		accountId,
 	};
 }
+
+export const openaiCodexOAuthProvider: OAuthProviderInterface = {
+	id: "openai-codex",
+	name: "ChatGPT Plus/Pro (Codex Subscription)",
+	usesCallbackServer: true,
+
+	async login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials> {
+		return loginOpenAICodex({
+			onAuth: callbacks.onAuth,
+			onPrompt: callbacks.onPrompt,
+			onProgress: callbacks.onProgress,
+			onManualCodeInput: callbacks.onManualCodeInput,
+		});
+	},
+
+	async refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials> {
+		return refreshOpenAICodexToken(credentials.refresh);
+	},
+
+	getApiKey(credentials: OAuthCredentials): string {
+		return credentials.access;
+	},
+};
--- a/packages/ai/src/utils/oauth/types.ts
+++ b/packages/ai/src/utils/oauth/types.ts
@ -1,19 +1,16 @@
+import type { Api, Model } from "../../types.js";
+
 export type OAuthCredentials = {
 	refresh: string;
 	access: string;
 	expires: number;
-	enterpriseUrl?: string;
-	projectId?: string;
-	email?: string;
-	accountId?: string;
+	[key: string]: unknown;
 };

-export type OAuthProvider =
-	| "anthropic"
-	| "github-copilot"
-	| "google-gemini-cli"
-	| "google-antigravity"
-	| "openai-codex";
+export type OAuthProviderId = string;
+
+/** @deprecated Use OAuthProviderId instead */
+export type OAuthProvider = OAuthProviderId;

 export type OAuthPrompt = {
 	message: string;
@ -26,8 +23,37 @@ export type OAuthAuthInfo = {
 	instructions?: string;
 };

+export interface OAuthLoginCallbacks {
+	onAuth: (info: OAuthAuthInfo) => void;
+	onPrompt: (prompt: OAuthPrompt) => Promise<string>;
+	onProgress?: (message: string) => void;
+	onManualCodeInput?: () => Promise<string>;
+	signal?: AbortSignal;
+}
+
+export interface OAuthProviderInterface {
+	readonly id: OAuthProviderId;
+	readonly name: string;
+
+	/** Run the login flow, return credentials to persist */
+	login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials>;
+
+	/** Whether login uses a local callback server and supports manual code input. */
+	usesCallbackServer?: boolean;
+
+	/** Refresh expired credentials, return updated credentials to persist */
+	refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials>;
+
+	/** Convert credentials to API key string for the provider */
+	getApiKey(credentials: OAuthCredentials): string;
+
+	/** Optional: modify models for this provider (e.g., update baseUrl) */
+	modifyModels?(models: Model<Api>[], credentials: OAuthCredentials): Model<Api>[];
+}
+
+/** @deprecated Use OAuthProviderInterface instead */
 export interface OAuthProviderInfo {
-	id: OAuthProvider;
+	id: OAuthProviderId;
 	name: string;
 	available: boolean;
 }
--- a/packages/coding-agent/docs/extensions.md
+++ b/packages/coding-agent/docs/extensions.md
@ -1146,6 +1146,67 @@ pi.events.on("my:event", (data) => { ... });
 pi.events.emit("my:event", { ... });
 ```

+### pi.registerProvider(name, config)
+
+Register or override a model provider dynamically. Useful for proxies, custom endpoints, or team-wide model configurations.
+
+```typescript
+// Register a new provider with custom models
+pi.registerProvider("my-proxy", {
+  baseUrl: "https://proxy.example.com",
+  apiKey: "PROXY_API_KEY",  // env var name or literal
+  api: "anthropic-messages",
+  models: [
+    {
+      id: "claude-sonnet-4-20250514",
+      name: "Claude 4 Sonnet (proxy)",
+      reasoning: false,
+      input: ["text", "image"],
+      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+      contextWindow: 200000,
+      maxTokens: 16384
+    }
+  ]
+});
+
+// Override baseUrl for an existing provider (keeps all models)
+pi.registerProvider("anthropic", {
+  baseUrl: "https://proxy.example.com"
+});
+
+// Register provider with OAuth support for /login
+pi.registerProvider("corporate-ai", {
+  baseUrl: "https://ai.corp.com",
+  api: "openai-responses",
+  models: [...],
+  oauth: {
+    name: "Corporate AI (SSO)",
+    async login(callbacks) {
+      // Custom OAuth flow
+      callbacks.onAuth({ url: "https://sso.corp.com/..." });
+      const code = await callbacks.onPrompt({ message: "Enter code:" });
+      return { refresh: code, access: code, expires: Date.now() + 3600000 };
+    },
+    async refreshToken(credentials) {
+      // Refresh logic
+      return credentials;
+    },
+    getApiKey(credentials) {
+      return credentials.access;
+    }
+  }
+});
+```
+
+**Config options:**
+- `baseUrl` - API endpoint URL. Required when defining models.
+- `apiKey` - API key or environment variable name. Required when defining models (unless `oauth` provided).
+- `api` - API type: `"anthropic-messages"`, `"openai-completions"`, `"openai-responses"`, etc.
+- `headers` - Custom headers to include in requests.
+- `authHeader` - If true, adds `Authorization: Bearer` header automatically.
+- `models` - Array of model definitions. If provided, replaces all existing models for this provider.
+- `oauth` - OAuth provider config for `/login` support. When provided, the provider appears in the login menu.
+
 ## State Management

 Extensions with state should store it in tool result `details` for proper branching support:
--- a/packages/coding-agent/src/core/auth-storage.ts
+++ b/packages/coding-agent/src/core/auth-storage.ts
@ -9,13 +9,11 @@
 import {
 	getEnvApiKey,
 	getOAuthApiKey,
-	loginAnthropic,
-	loginAntigravity,
-	loginGeminiCli,
-	loginGitHubCopilot,
-	loginOpenAICodex,
+	getOAuthProvider,
+	getOAuthProviders,
 	type OAuthCredentials,
-	type OAuthProvider,
+	type OAuthLoginCallbacks,
+	type OAuthProviderId,
 } from "@mariozechner/pi-ai";
 import { chmodSync, existsSync, mkdirSync, readFileSync, writeFileSync } from "fs";
 import { dirname, join } from "path";
@ -156,54 +154,14 @@ export class AuthStorage {
 	/**
 	 * Login to an OAuth provider.
 	 */
-	async login(
-		provider: OAuthProvider,
-		callbacks: {
-			onAuth: (info: { url: string; instructions?: string }) => void;
-			onPrompt: (prompt: { message: string; placeholder?: string }) => Promise<string>;
-			onProgress?: (message: string) => void;
-			/** For providers with local callback servers (e.g., openai-codex), races with browser callback */
-			onManualCodeInput?: () => Promise<string>;
-			/** For cancellation support (e.g., github-copilot polling) */
-			signal?: AbortSignal;
-		},
-	): Promise<void> {
-		let credentials: OAuthCredentials;
-
-		switch (provider) {
-			case "anthropic":
-				credentials = await loginAnthropic(
-					(url) => callbacks.onAuth({ url }),
-					() => callbacks.onPrompt({ message: "Paste the authorization code:" }),
-				);
-				break;
-			case "github-copilot":
-				credentials = await loginGitHubCopilot({
-					onAuth: (url, instructions) => callbacks.onAuth({ url, instructions }),
-					onPrompt: callbacks.onPrompt,
-					onProgress: callbacks.onProgress,
-					signal: callbacks.signal,
-				});
-				break;
-			case "google-gemini-cli":
-				credentials = await loginGeminiCli(callbacks.onAuth, callbacks.onProgress, callbacks.onManualCodeInput);
-				break;
-			case "google-antigravity":
-				credentials = await loginAntigravity(callbacks.onAuth, callbacks.onProgress, callbacks.onManualCodeInput);
-				break;
-			case "openai-codex":
-				credentials = await loginOpenAICodex({
-					onAuth: callbacks.onAuth,
-					onPrompt: callbacks.onPrompt,
-					onProgress: callbacks.onProgress,
-					onManualCodeInput: callbacks.onManualCodeInput,
-				});
-				break;
-			default:
-				throw new Error(`Unknown OAuth provider: ${provider}`);
+	async login(providerId: OAuthProviderId, callbacks: OAuthLoginCallbacks): Promise<void> {
+		const provider = getOAuthProvider(providerId);
+		if (!provider) {
+			throw new Error(`Unknown OAuth provider: ${providerId}`);
 		}

-		this.set(provider, { type: "oauth", ...credentials });
+		const credentials = await provider.login(callbacks);
+		this.set(providerId, { type: "oauth", ...credentials });
 	}

 	/**
@ -219,8 +177,13 @@ export class AuthStorage {
 	 * This ensures only one instance refreshes while others wait and use the result.
 	 */
 	private async refreshOAuthTokenWithLock(
-		provider: OAuthProvider,
+		providerId: OAuthProviderId,
 	): Promise<{ apiKey: string; newCredentials: OAuthCredentials } | null> {
+		const provider = getOAuthProvider(providerId);
+		if (!provider) {
+			return null;
+		}
+
 		// Ensure auth file exists for locking
 		if (!existsSync(this.authPath)) {
 			const dir = dirname(this.authPath);
@ -250,7 +213,7 @@ export class AuthStorage {
 			// Re-read file after acquiring lock - another instance may have refreshed
 			this.reload();

-			const cred = this.data[provider];
+			const cred = this.data[providerId];
 			if (cred?.type !== "oauth") {
 				return null;
 			}
@ -259,10 +222,7 @@ export class AuthStorage {
 			// (another instance may have already refreshed it)
 			if (Date.now() < cred.expires) {
 				// Token is now valid - another instance refreshed it
-				const needsProjectId = provider === "google-gemini-cli" || provider === "google-antigravity";
-				const apiKey = needsProjectId
-					? JSON.stringify({ token: cred.access, projectId: cred.projectId })
-					: cred.access;
+				const apiKey = provider.getApiKey(cred);
 				return { apiKey, newCredentials: cred };
 			}

@ -274,9 +234,9 @@ export class AuthStorage {
 				}
 			}

-			const result = await getOAuthApiKey(provider, oauthCreds);
+			const result = await getOAuthApiKey(providerId, oauthCreds);
 			if (result) {
-				this.data[provider] = { type: "oauth", ...result.newCredentials };
+				this.data[providerId] = { type: "oauth", ...result.newCredentials };
 				this.save();
 				return result;
 			}
@ -303,41 +263,44 @@ export class AuthStorage {
 	 * 4. Environment variable
 	 * 5. Fallback resolver (models.json custom providers)
 	 */
-	async getApiKey(provider: string): Promise<string | undefined> {
+	async getApiKey(providerId: string): Promise<string | undefined> {
 		// Runtime override takes highest priority
-		const runtimeKey = this.runtimeOverrides.get(provider);
+		const runtimeKey = this.runtimeOverrides.get(providerId);
 		if (runtimeKey) {
 			return runtimeKey;
 		}

-		const cred = this.data[provider];
+		const cred = this.data[providerId];

 		if (cred?.type === "api_key") {
 			return cred.key;
 		}

 		if (cred?.type === "oauth") {
+			const provider = getOAuthProvider(providerId);
+			if (!provider) {
+				// Unknown OAuth provider, can't get API key
+				return undefined;
+			}
+
 			// Check if token needs refresh
 			const needsRefresh = Date.now() >= cred.expires;

 			if (needsRefresh) {
 				// Use locked refresh to prevent race conditions
 				try {
-					const result = await this.refreshOAuthTokenWithLock(provider as OAuthProvider);
+					const result = await this.refreshOAuthTokenWithLock(providerId);
 					if (result) {
 						return result.apiKey;
 					}
 				} catch {
 					// Refresh failed - re-read file to check if another instance succeeded
 					this.reload();
-					const updatedCred = this.data[provider];
+					const updatedCred = this.data[providerId];

 					if (updatedCred?.type === "oauth" && Date.now() < updatedCred.expires) {
 						// Another instance refreshed successfully, use those credentials
-						const needsProjectId = provider === "google-gemini-cli" || provider === "google-antigravity";
-						return needsProjectId
-							? JSON.stringify({ token: updatedCred.access, projectId: updatedCred.projectId })
-							: updatedCred.access;
+						return provider.getApiKey(updatedCred);
 					}

 					// Refresh truly failed - return undefined so model discovery skips this provider
@ -346,16 +309,22 @@ export class AuthStorage {
 				}
 			} else {
 				// Token not expired, use current access token
-				const needsProjectId = provider === "google-gemini-cli" || provider === "google-antigravity";
-				return needsProjectId ? JSON.stringify({ token: cred.access, projectId: cred.projectId }) : cred.access;
+				return provider.getApiKey(cred);
 			}
 		}

 		// Fall back to environment variable
-		const envKey = getEnvApiKey(provider);
+		const envKey = getEnvApiKey(providerId);
 		if (envKey) return envKey;

 		// Fall back to custom resolver (e.g., models.json custom providers)
-		return this.fallbackResolver?.(provider) ?? undefined;
+		return this.fallbackResolver?.(providerId) ?? undefined;
+	}
+
+	/**
+	 * Get all registered OAuth providers
+	 */
+	getOAuthProviders() {
+		return getOAuthProviders();
 	}
 }
--- a/packages/coding-agent/src/core/extensions/index.ts
+++ b/packages/coding-agent/src/core/extensions/index.ts
@ -76,6 +76,9 @@ export type {
 	MessageRenderOptions,
 	ModelSelectEvent,
 	ModelSelectSource,
+	// Provider Registration
+	ProviderConfig,
+	ProviderModelConfig,
 	ReadToolResultEvent,
 	// Commands
 	RegisteredCommand,
--- a/packages/coding-agent/src/core/extensions/loader.ts
+++ b/packages/coding-agent/src/core/extensions/loader.ts
@ -32,6 +32,7 @@ import type {
 	ExtensionRuntime,
 	LoadExtensionsResult,
 	MessageRenderer,
+	ProviderConfig,
 	RegisteredCommand,
 	ToolDefinition,
 } from "./types.js";
@ -122,6 +123,7 @@ export function createExtensionRuntime(): ExtensionRuntime {
 		getThinkingLevel: notInitialized,
 		setThinkingLevel: notInitialized,
 		flagValues: new Map(),
+		pendingProviderRegistrations: [],
 	};
 }

@ -238,6 +240,10 @@ function createExtensionAPI(
 			runtime.setThinkingLevel(level);
 		},

+		registerProvider(name: string, config: ProviderConfig) {
+			runtime.pendingProviderRegistrations.push({ name, config });
+		},
+
 		events: eventBus,
 	} as ExtensionAPI;

--- a/packages/coding-agent/src/core/extensions/runner.ts
+++ b/packages/coding-agent/src/core/extensions/runner.ts
@ -203,6 +203,12 @@ export class ExtensionRunner {
 		this.shutdownHandler = contextActions.shutdown;
 		this.getContextUsageFn = contextActions.getContextUsage;
 		this.compactFn = contextActions.compact;
+
+		// Process provider registrations queued during extension loading
+		for (const { name, config } of this.runtime.pendingProviderRegistrations) {
+			this.modelRegistry.registerProvider(name, config);
+		}
+		this.runtime.pendingProviderRegistrations = [];
 	}

 	bindCommandContext(actions?: ExtensionCommandContextActions): void {
--- a/packages/coding-agent/src/core/extensions/types.ts
+++ b/packages/coding-agent/src/core/extensions/types.ts
@ -14,7 +14,15 @@ import type {
 	AgentToolUpdateCallback,
 	ThinkingLevel,
 } from "@mariozechner/pi-agent-core";
-import type { ImageContent, Model, TextContent, ToolResultMessage } from "@mariozechner/pi-ai";
+import type {
+	Api,
+	ImageContent,
+	Model,
+	OAuthCredentials,
+	OAuthLoginCallbacks,
+	TextContent,
+	ToolResultMessage,
+} from "@mariozechner/pi-ai";
 import type {
 	AutocompleteItem,
 	Component,
@ -854,10 +862,119 @@ export interface ExtensionAPI {
 	/** Set thinking level (clamped to model capabilities). */
 	setThinkingLevel(level: ThinkingLevel): void;

+	// =========================================================================
+	// Provider Registration
+	// =========================================================================
+
+	/**
+	 * Register or override a model provider.
+	 *
+	 * If `models` is provided: replaces all existing models for this provider.
+	 * If only `baseUrl` is provided: overrides the URL for existing models.
+	 * If `oauth` is provided: registers OAuth provider for /login support.
+	 *
+	 * @example
+	 * // Register a new provider with custom models
+	 * pi.registerProvider("my-proxy", {
+	 *   baseUrl: "https://proxy.example.com",
+	 *   apiKey: "PROXY_API_KEY",
+	 *   api: "anthropic-messages",
+	 *   models: [
+	 *     {
+	 *       id: "claude-sonnet-4-20250514",
+	 *       name: "Claude 4 Sonnet (proxy)",
+	 *       reasoning: false,
+	 *       input: ["text", "image"],
+	 *       cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+	 *       contextWindow: 200000,
+	 *       maxTokens: 16384
+	 *     }
+	 *   ]
+	 * });
+	 *
+	 * @example
+	 * // Override baseUrl for an existing provider
+	 * pi.registerProvider("anthropic", {
+	 *   baseUrl: "https://proxy.example.com"
+	 * });
+	 *
+	 * @example
+	 * // Register provider with OAuth support
+	 * pi.registerProvider("corporate-ai", {
+	 *   baseUrl: "https://ai.corp.com",
+	 *   api: "openai-responses",
+	 *   models: [...],
+	 *   oauth: {
+	 *     name: "Corporate AI (SSO)",
+	 *     async login(callbacks) { ... },
+	 *     async refreshToken(credentials) { ... },
+	 *     getApiKey(credentials) { return credentials.access; }
+	 *   }
+	 * });
+	 */
+	registerProvider(name: string, config: ProviderConfig): void;
+
 	/** Shared event bus for extension communication. */
 	events: EventBus;
 }

+// ============================================================================
+// Provider Registration Types
+// ============================================================================
+
+/** Configuration for registering a provider via pi.registerProvider(). */
+export interface ProviderConfig {
+	/** Base URL for the API endpoint. Required when defining models. */
+	baseUrl?: string;
+	/** API key or environment variable name. Required when defining models (unless oauth provided). */
+	apiKey?: string;
+	/** API type. Required at provider or model level when defining models. */
+	api?: Api;
+	/** Custom headers to include in requests. */
+	headers?: Record<string, string>;
+	/** If true, adds Authorization: Bearer header with the resolved API key. */
+	authHeader?: boolean;
+	/** Models to register. If provided, replaces all existing models for this provider. */
+	models?: ProviderModelConfig[];
+	/** OAuth provider for /login support. The `id` is set automatically from the provider name. */
+	oauth?: {
+		/** Display name for the provider in login UI. */
+		name: string;
+		/** Run the login flow, return credentials to persist. */
+		login(callbacks: OAuthLoginCallbacks): Promise<OAuthCredentials>;
+		/** Refresh expired credentials, return updated credentials to persist. */
+		refreshToken(credentials: OAuthCredentials): Promise<OAuthCredentials>;
+		/** Convert credentials to API key string for the provider. */
+		getApiKey(credentials: OAuthCredentials): string;
+		/** Optional: modify models for this provider (e.g., update baseUrl based on credentials). */
+		modifyModels?(models: Model<Api>[], credentials: OAuthCredentials): Model<Api>[];
+	};
+}
+
+/** Configuration for a model within a provider. */
+export interface ProviderModelConfig {
+	/** Model ID (e.g., "claude-sonnet-4-20250514"). */
+	id: string;
+	/** Display name (e.g., "Claude 4 Sonnet"). */
+	name: string;
+	/** API type override for this model. */
+	api?: Api;
+	/** Whether the model supports extended thinking. */
+	reasoning: boolean;
+	/** Supported input types. */
+	input: ("text" | "image")[];
+	/** Cost per token (for tracking, can be 0). */
+	cost: { input: number; output: number; cacheRead: number; cacheWrite: number };
+	/** Maximum context window size in tokens. */
+	contextWindow: number;
+	/** Maximum output tokens. */
+	maxTokens: number;
+	/** Custom headers for this model. */
+	headers?: Record<string, string>;
+	/** OpenAI compatibility settings. */
+	compat?: Model<Api>["compat"];
+}
+
 /** Extension factory function type. Supports both sync and async initialization. */
 export type ExtensionFactory = (pi: ExtensionAPI) => void | Promise<void>;

@ -926,6 +1043,8 @@ export type SetLabelHandler = (entryId: string, label: string | undefined) => vo
 */
 export interface ExtensionRuntimeState {
 	flagValues: Map<string, boolean | string>;
+	/** Provider registrations queued during extension loading, processed when runner binds */
+	pendingProviderRegistrations: Array<{ name: string; config: ProviderConfig }>;
 }

 /**
--- a/packages/coding-agent/src/core/model-registry.ts
+++ b/packages/coding-agent/src/core/model-registry.ts
@ -4,12 +4,12 @@

 import {
 	type Api,
-	getGitHubCopilotBaseUrl,
 	getModels,
 	getProviders,
 	type KnownProvider,
 	type Model,
-	normalizeDomain,
+	type OAuthProviderInterface,
+	registerOAuthProvider,
 } from "@mariozechner/pi-ai";
 import { type Static, Type } from "@sinclair/typebox";
 import AjvModule from "ajv";
@ -26,7 +26,13 @@ const OpenAICompletionsCompatSchema = Type.Object({
 	supportsStore: Type.Optional(Type.Boolean()),
 	supportsDeveloperRole: Type.Optional(Type.Boolean()),
 	supportsReasoningEffort: Type.Optional(Type.Boolean()),
+	supportsUsageInStreaming: Type.Optional(Type.Boolean()),
 	maxTokensField: Type.Optional(Type.Union([Type.Literal("max_completion_tokens"), Type.Literal("max_tokens")])),
+	requiresToolResultName: Type.Optional(Type.Boolean()),
+	requiresAssistantAfterToolResult: Type.Optional(Type.Boolean()),
+	requiresThinkingAsText: Type.Optional(Type.Boolean()),
+	requiresMistralToolIds: Type.Optional(Type.Boolean()),
+	thinkingFormat: Type.Optional(Type.Union([Type.Literal("openai"), Type.Literal("zai")])),
 });

 const OpenAIResponsesCompatSchema = Type.Object({
@ -174,6 +180,7 @@ export function clearApiKeyCache(): void {
 export class ModelRegistry {
 	private models: Model<Api>[] = [];
 	private customProviderApiKeys: Map<string, string> = new Map();
+	private registeredProviders: Map<string, ProviderConfigInput> = new Map();
 	private loadError: string | undefined = undefined;

 	constructor(
@ -200,6 +207,10 @@ export class ModelRegistry {
 		this.customProviderApiKeys.clear();
 		this.loadError = undefined;
 		this.loadModels();
+
+		for (const [providerName, config] of this.registeredProviders.entries()) {
+			this.applyProviderConfig(providerName, config);
+		}
 	}

 	/**
@ -224,19 +235,17 @@ export class ModelRegistry {
 		}

 		const builtInModels = this.loadBuiltInModels(replacedProviders, overrides);
-		const combined = [...builtInModels, ...customModels];
+		let combined = [...builtInModels, ...customModels];

-		// Update github-copilot base URL based on OAuth credentials
-		const copilotCred = this.authStorage.get("github-copilot");
-		if (copilotCred?.type === "oauth") {
-			const domain = copilotCred.enterpriseUrl
-				? (normalizeDomain(copilotCred.enterpriseUrl) ?? undefined)
-				: undefined;
-			const baseUrl = getGitHubCopilotBaseUrl(copilotCred.access, domain);
-			this.models = combined.map((m) => (m.provider === "github-copilot" ? { ...m, baseUrl } : m));
-		} else {
-			this.models = combined;
+		// Let OAuth providers modify their models (e.g., update baseUrl)
+		for (const oauthProvider of this.authStorage.getOAuthProviders()) {
+			const cred = this.authStorage.get(oauthProvider.id);
+			if (cred?.type === "oauth" && oauthProvider.modifyModels) {
+				combined = oauthProvider.modifyModels(combined, cred);
+			}
 		}
+
+		this.models = combined;
 	}

 	/** Load built-in models, skipping replaced providers and applying overrides */
@ -449,4 +458,118 @@ export class ModelRegistry {
 		const cred = this.authStorage.get(model.provider);
 		return cred?.type === "oauth";
 	}
+
+	/**
+	 * Register a provider dynamically (from extensions).
+	 *
+	 * If provider has models: replaces all existing models for this provider.
+	 * If provider has only baseUrl/headers: overrides existing models' URLs.
+	 * If provider has oauth: registers OAuth provider for /login support.
+	 */
+	registerProvider(providerName: string, config: ProviderConfigInput): void {
+		this.registeredProviders.set(providerName, config);
+		this.applyProviderConfig(providerName, config);
+	}
+
+	private applyProviderConfig(providerName: string, config: ProviderConfigInput): void {
+		// Register OAuth provider if provided
+		if (config.oauth) {
+			// Ensure the OAuth provider ID matches the provider name
+			const oauthProvider: OAuthProviderInterface = {
+				...config.oauth,
+				id: providerName,
+			};
+			registerOAuthProvider(oauthProvider);
+		}
+
+		// Store API key for auth resolution
+		if (config.apiKey) {
+			this.customProviderApiKeys.set(providerName, config.apiKey);
+		}
+
+		if (config.models && config.models.length > 0) {
+			// Full replacement: remove existing models for this provider
+			this.models = this.models.filter((m) => m.provider !== providerName);
+
+			// Validate required fields
+			if (!config.baseUrl) {
+				throw new Error(`Provider ${providerName}: "baseUrl" is required when defining models.`);
+			}
+			if (!config.apiKey && !config.oauth) {
+				throw new Error(`Provider ${providerName}: "apiKey" or "oauth" is required when defining models.`);
+			}
+
+			// Parse and add new models
+			for (const modelDef of config.models) {
+				const api = modelDef.api || config.api;
+				if (!api) {
+					throw new Error(`Provider ${providerName}, model ${modelDef.id}: no "api" specified.`);
+				}
+
+				// Merge headers
+				const providerHeaders = resolveHeaders(config.headers);
+				const modelHeaders = resolveHeaders(modelDef.headers);
+				let headers = providerHeaders || modelHeaders ? { ...providerHeaders, ...modelHeaders } : undefined;
+
+				// If authHeader is true, add Authorization header
+				if (config.authHeader && config.apiKey) {
+					const resolvedKey = resolveConfigValue(config.apiKey);
+					if (resolvedKey) {
+						headers = { ...headers, Authorization: `Bearer ${resolvedKey}` };
+					}
+				}
+
+				this.models.push({
+					id: modelDef.id,
+					name: modelDef.name,
+					api: api as Api,
+					provider: providerName,
+					baseUrl: config.baseUrl,
+					reasoning: modelDef.reasoning,
+					input: modelDef.input as ("text" | "image")[],
+					cost: modelDef.cost,
+					contextWindow: modelDef.contextWindow,
+					maxTokens: modelDef.maxTokens,
+					headers,
+					compat: modelDef.compat,
+				} as Model<Api>);
+			}
+		} else if (config.baseUrl) {
+			// Override-only: update baseUrl/headers for existing models
+			const resolvedHeaders = resolveHeaders(config.headers);
+			this.models = this.models.map((m) => {
+				if (m.provider !== providerName) return m;
+				return {
+					...m,
+					baseUrl: config.baseUrl ?? m.baseUrl,
+					headers: resolvedHeaders ? { ...m.headers, ...resolvedHeaders } : m.headers,
+				};
+			});
+		}
+	}
+}
+
+/**
+ * Input type for registerProvider API.
+ */
+export interface ProviderConfigInput {
+	baseUrl?: string;
+	apiKey?: string;
+	api?: Api;
+	headers?: Record<string, string>;
+	authHeader?: boolean;
+	/** OAuth provider for /login support */
+	oauth?: Omit<OAuthProviderInterface, "id">;
+	models?: Array<{
+		id: string;
+		name: string;
+		api?: Api;
+		reasoning: boolean;
+		input: ("text" | "image")[];
+		cost: { input: number; output: number; cacheRead: number; cacheWrite: number };
+		contextWindow: number;
+		maxTokens: number;
+		headers?: Record<string, string>;
+		compat?: Model<Api>["compat"];
+	}>;
 }
--- a/packages/coding-agent/src/index.ts
+++ b/packages/coding-agent/src/index.ts
@ -76,6 +76,8 @@ export type {
 	LoadExtensionsResult,
 	MessageRenderer,
 	MessageRenderOptions,
+	ProviderConfig,
+	ProviderModelConfig,
 	RegisteredCommand,
 	RegisteredTool,
 	SessionBeforeCompactEvent,
--- a/packages/coding-agent/src/main.ts
+++ b/packages/coding-agent/src/main.ts
@ -432,10 +432,6 @@ export async function main(args: string[]) {
 	// Run migrations (pass cwd for project-local migrations)
 	const { migratedAuthProviders: migratedProviders, deprecationWarnings } = runMigrations(process.cwd());

-	// Create AuthStorage and ModelRegistry upfront
-	const authStorage = new AuthStorage();
-	const modelRegistry = new ModelRegistry(authStorage);
-
 	// First pass: parse args to get --extension paths
 	const firstPass = parseArgs(args);

@ -443,6 +439,8 @@ export async function main(args: string[]) {
 	const cwd = process.cwd();
 	const agentDir = getAgentDir();
 	const settingsManager = SettingsManager.create(cwd, agentDir);
+	const authStorage = new AuthStorage();
+	const modelRegistry = new ModelRegistry(authStorage, getModelsPath());

 	const resourceLoader = new DefaultResourceLoader({
 		cwd,
--- a/packages/coding-agent/src/modes/interactive/components/oauth-selector.ts
+++ b/packages/coding-agent/src/modes/interactive/components/oauth-selector.ts
@ -1,4 +1,4 @@
-import { getOAuthProviders, type OAuthProviderInfo } from "@mariozechner/pi-ai";
+import { getOAuthProviders, type OAuthProviderInterface } from "@mariozechner/pi-ai";
 import { Container, getEditorKeybindings, Spacer, TruncatedText } from "@mariozechner/pi-tui";
 import type { AuthStorage } from "../../../core/auth-storage.js";
 import { theme } from "../theme/theme.js";
@ -9,7 +9,7 @@ import { DynamicBorder } from "./dynamic-border.js";
 */
 export class OAuthSelectorComponent extends Container {
 	private listContainer: Container;
-	private allProviders: OAuthProviderInfo[] = [];
+	private allProviders: OAuthProviderInterface[] = [];
 	private selectedIndex: number = 0;
 	private mode: "login" | "logout";
 	private authStorage: AuthStorage;
@ -66,7 +66,6 @@ export class OAuthSelectorComponent extends Container {
 			if (!provider) continue;

 			const isSelected = i === this.selectedIndex;
-			const isAvailable = provider.available;

 			// Check if user is logged in for this provider
 			const credentials = this.authStorage.get(provider.id);
@ -76,10 +75,10 @@ export class OAuthSelectorComponent extends Container {
 			let line = "";
 			if (isSelected) {
 				const prefix = theme.fg("accent", "→ ");
-				const text = isAvailable ? theme.fg("accent", provider.name) : theme.fg("dim", provider.name);
+				const text = theme.fg("accent", provider.name);
 				line = prefix + text + statusIndicator;
 			} else {
-				const text = isAvailable ? `  ${provider.name}` : theme.fg("dim", `  ${provider.name}`);
+				const text = `  ${provider.name}`;
 				line = text + statusIndicator;
 			}

@ -109,7 +108,7 @@ export class OAuthSelectorComponent extends Container {
 		// Enter
 		else if (kb.matches(keyData, "selectConfirm")) {
 			const selectedProvider = this.allProviders[this.selectedIndex];
-			if (selectedProvider?.available) {
+			if (selectedProvider) {
 				this.onSelectCallback(selectedProvider.id);
 			}
 		}
--- a/packages/coding-agent/src/modes/interactive/interactive-mode.ts
+++ b/packages/coding-agent/src/modes/interactive/interactive-mode.ts
@ -3529,8 +3529,7 @@ export class InteractiveMode {
 		const providerName = providerInfo?.name || providerId;

 		// Providers that use callback servers (can paste redirect URL)
-		const usesCallbackServer =
-			providerId === "openai-codex" || providerId === "google-gemini-cli" || providerId === "google-antigravity";
+		const usesCallbackServer = providerInfo?.usesCallbackServer ?? false;

 		// Create login dialog component
 		const dialog = new LoginDialogComponent(this.ui, providerId, (_success, _message) => {