feat(ai): add Radius gateway support

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

@@ -6,10 +6,10 @@ import {
 	type AnthropicMessagesCompat,
 	type Api,
 	type AssistantMessageEventStream,
+	type BuiltinProvider,
 	type Context,
 	getModels,
 	getProviders,
-	type KnownProvider,
 	type Model,
 	type OAuthProviderInterface,
 	type OpenAICompletionsCompat,
@@ -29,6 +29,7 @@ import { stripJsonComments } from "../utils/json.ts";
 import { normalizePath } from "../utils/paths.ts";
 import type { AuthStatus, AuthStorage } from "./auth-storage.ts";
 import { BUILT_IN_PROVIDER_DISPLAY_NAMES } from "./provider-display-names.ts";
+import { registerCustomRadiusOAuthProvider } from "./radius.ts";
 import {
 	clearConfigValueCache,
 	getConfigValueEnvVarNames,
@@ -224,6 +225,9 @@ const ProviderConfigSchema = Type.Object({
 	baseUrl: Type.Optional(Type.String({ minLength: 1 })),
 	apiKey: Type.Optional(Type.String({ minLength: 1 })),
 	api: Type.Optional(Type.String({ minLength: 1 })),
+	/** OAuth flavor spoken by this provider's endpoint. Registers a sign-in
+	 * provider with a dynamic model catalog (e.g. a custom Radius gateway). */
+	oauth: Type.Optional(Type.Literal("radius")),
 	headers: Type.Optional(Type.Record(Type.String(), Type.String())),
 	compat: Type.Optional(ProviderCompatSchema),
 	authHeader: Type.Optional(Type.Boolean()),
@@ -453,7 +457,7 @@ export class ModelRegistry {
 		modelOverrides: Map<string, Map<string, ModelOverride>>,
 	): Model<Api>[] {
 		return getProviders().flatMap((provider) => {
-			const models = getModels(provider as KnownProvider) as Model<Api>[];
+			const models = getModels(provider as BuiltinProvider) as Model<Api>[];
 			const providerOverride = overrides.get(provider);
 			const perModelOverrides = modelOverrides.get(provider);
 
@@ -537,6 +541,12 @@ export class ModelRegistry {
 					});
 				}
 
+				if (providerConfig.oauth === "radius") {
+					// Must run before the modifyModels loop in loadModels() so the
+					// credential-cached catalog is injected on this load.
+					registerCustomRadiusOAuthProvider(providerName, providerConfig.name, providerConfig.baseUrl!);
+				}
+
 				this.storeProviderRequestConfig(providerName, providerConfig);
 
 				if (providerConfig.modelOverrides) {
@@ -568,7 +578,11 @@ export class ModelRegistry {
 			const hasModelOverrides =
 				providerConfig.modelOverrides && Object.keys(providerConfig.modelOverrides).length > 0;
 
-			if (models.length === 0) {
+			if (providerConfig.oauth && !providerConfig.baseUrl) {
+				throw new Error(`Provider ${providerName}: "baseUrl" is required when "oauth" is set.`);
+			}
+
+			if (models.length === 0 && !providerConfig.oauth) {
 				// Override-only config: needs baseUrl, headers, compat, modelOverrides, or some combination.
 				if (!providerConfig.baseUrl && !providerConfig.headers && !providerConfig.compat && !hasModelOverrides) {
 					throw new Error(
@@ -614,7 +628,7 @@ export class ModelRegistry {
 		const getBuiltInDefaults = (providerName: string): { api: string; baseUrl: string } | undefined => {
 			if (!builtInProviders.has(providerName)) return undefined;
 			if (builtInDefaultsCache.has(providerName)) return builtInDefaultsCache.get(providerName);
-			const builtIn = getModels(providerName as KnownProvider) as Model<Api>[];
+			const builtIn = getModels(providerName as BuiltinProvider) as Model<Api>[];
 			if (builtIn.length === 0) return undefined;
 			const defaults = { api: builtIn[0].api, baseUrl: builtIn[0].baseUrl };
 			builtInDefaultsCache.set(providerName, defaults);

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

@@ -18,6 +18,7 @@ export const defaultModelPerProvider: Record<KnownProvider, string> = {
 	openai: "gpt-5.5",
 	"azure-openai-responses": "gpt-5.4",
 	"openai-codex": "gpt-5.5",
+	radius: "auto",
 	nvidia: "nvidia/nemotron-3-super-120b-a12b",
 	deepseek: "deepseek-v4-pro",
 	google: "gemini-3.1-pro-preview",

packages/coding-agent/src/core/provider-display-names.ts

@@ -23,6 +23,7 @@ export const BUILT_IN_PROVIDER_DISPLAY_NAMES: Record<string, string> = {
 	"opencode-go": "OpenCode Go",
 	openai: "OpenAI",
 	openrouter: "OpenRouter",
+	radius: "Radius",
 	together: "Together AI",
 	"vercel-ai-gateway": "Vercel AI Gateway",
 	xai: "xAI",

packages/coding-agent/src/core/radius.ts

@@ -0,0 +1,34 @@
+/**
+ * Radius (pi-messages gateway) provider wiring.
+ *
+ * The main Radius provider is a built-in OAuth provider in pi-ai; models are
+ * dynamic, cached on the stored OAuth credential (`gatewayConfig`) and
+ * injected via the OAuth provider's `modifyModels` hook, so startup, /reload,
+ * and registry refreshes work without network access. The catalog refreshes
+ * on login and on every token refresh.
+ *
+ * Additional gateways (e.g. a local dev gateway) can be declared in
+ * models.json with `"oauth": "radius"`; each entry is an independent Radius
+ * instance with its own credentials and catalog.
+ */
+
+import { createRadiusOAuthProvider, registerOAuthProvider } from "@earendil-works/pi-ai/oauth";
+
+export const RADIUS_PROVIDER_ID = "radius";
+
+/**
+ * Register a Radius-style OAuth provider for a custom gateway declared in
+ * models.json (`"oauth": "radius"`). Runs on every models.json load so the
+ * registration survives `resetOAuthProviders()` during registry refreshes.
+ */
+export function registerCustomRadiusOAuthProvider(id: string, name: string | undefined, gateway: string): void {
+	registerOAuthProvider(
+		createRadiusOAuthProvider({
+			id,
+			name: name ?? id,
+			// Tolerate an API base URL: the gateway root is what the OAuth and
+			// config discovery endpoints hang off.
+			gateway: gateway.replace(/\/v1\/?$/u, ""),
+		}),
+	);
+}