zen: use gpt-5-nano as small model

packages/console/app/src/routes/zen/util/handler.ts

@@ -291,7 +291,7 @@ export async function handler(
 
   async function authenticate(modelInfo: ModelInfo, providerInfo: ProviderInfo) {
     const apiKey = opts.parseApiKey(input.request.headers)
-    if (!apiKey) {
+    if (!apiKey || apiKey === "public") {
       if (modelInfo.allowAnonymous) return
       throw new AuthError("Missing API key.")
     }

packages/opencode/src/provider/provider.ts

@@ -53,7 +53,7 @@ export namespace Provider {
 
       return {
         autoload: Object.keys(input.models).length > 0,
-        options: {},
+        options: hasKey ? {} : { apiKey: "public" },
       }
     },
     openai: async () => {
@@ -582,6 +582,9 @@ export namespace Provider {
     if (providerID === "github-copilot") {
       priority = priority.filter((m) => m !== "claude-haiku-4.5")
     }
+    if (providerID === "opencode" || providerID === "local") {
+      priority = ["gpt-5-nano"]
+    }
     for (const item of priority) {
       for (const model of Object.keys(provider.info.models)) {
         if (model.includes(item)) return getModel(providerID, model)