🤖 fix: auto-naming works with mux-gateway

When users only have mux-gateway configured (no direct Anthropic/OpenAI API
keys), getPreferredNameModel now tries gateway versions of preferred models.

The fix:
1. After trying each preferred model directly (anthropic:claude-haiku-4-5),
   also try the gateway version (mux-gateway:anthropic/claude-haiku-4-5)
2. Still prefers direct access when available for lower latency

This ensures auto-naming works for gateway-only users while maintaining
optimal performance for users with direct API keys.

---
_Generated with `mux` • Model: `anthropic:claude-opus-4-5` • Thinking: `high`_

Author: ammar-agent

src/node/services/workspaceTitleGenerator.test.ts

@@ -30,6 +30,9 @@ function createMockAIService(availableModels: string[]): AIService {
 describe("workspaceTitleGenerator", () => {
   const HAIKU_ID = getKnownModel("HAIKU").id;
   const GPT_MINI_ID = getKnownModel("GPT_MINI").id;
+  // Gateway format: mux-gateway:provider/model instead of provider:model
+  const HAIKU_GATEWAY = "mux-gateway:anthropic/claude-haiku-4-5";
+  const GPT_MINI_GATEWAY = "mux-gateway:openai/gpt-5.1-codex-mini";
 
   it("getPreferredNameModel returns null when no models available", async () => {
     const aiService = createMockAIService([]);
@@ -47,4 +50,25 @@ describe("workspaceTitleGenerator", () => {
     const model = await getPreferredNameModel(aiService);
     expect(model).toBe(GPT_MINI_ID);
   });
+
+  it("getPreferredNameModel uses gateway Haiku when direct is unavailable", async () => {
+    // User has mux-gateway configured but no direct Anthropic/OpenAI API keys
+    const aiService = createMockAIService([HAIKU_GATEWAY, GPT_MINI_GATEWAY]);
+    const model = await getPreferredNameModel(aiService);
+    expect(model).toBe(HAIKU_GATEWAY);
+  });
+
+  it("getPreferredNameModel falls back to gateway GPT Mini", async () => {
+    // Only GPT Mini available via gateway
+    const aiService = createMockAIService([GPT_MINI_GATEWAY]);
+    const model = await getPreferredNameModel(aiService);
+    expect(model).toBe(GPT_MINI_GATEWAY);
+  });
+
+  it("getPreferredNameModel prefers direct over gateway", async () => {
+    // Both direct and gateway available - should prefer direct
+    const aiService = createMockAIService([HAIKU_ID, HAIKU_GATEWAY]);
+    const model = await getPreferredNameModel(aiService);
+    expect(model).toBe(HAIKU_ID);
+  });
 });

src/node/services/workspaceTitleGenerator.ts

@@ -11,6 +11,16 @@ import crypto from "crypto";
 /** Models to try in order of preference for name generation (small, fast models) */
 const PREFERRED_MODELS = [getKnownModel("HAIKU").id, getKnownModel("GPT_MINI").id] as const;
 
+/**
+ * Convert a canonical model string (provider:model) to mux-gateway format.
+ * Example: "anthropic:claude-haiku-4-5" → "mux-gateway:anthropic/claude-haiku-4-5"
+ */
+function toGatewayModel(modelId: string): string {
+  const [provider, model] = modelId.split(":", 2);
+  if (!provider || !model) return modelId;
+  return `mux-gateway:${provider}/${model}`;
+}
+
 /** Schema for AI-generated workspace identity (area name + descriptive title) */
 const workspaceIdentitySchema = z.object({
   name: z
@@ -39,14 +49,24 @@ export interface WorkspaceIdentity {
  * Get the preferred model for name generation by testing which models the AIService
  * can actually create. This delegates credential checking to AIService, avoiding
  * duplication of provider-specific API key logic.
+ *
+ * Tries each preferred model first as direct provider access, then via mux-gateway.
+ * This ensures gateway users still get fast/cheap models for name generation.
  */
 export async function getPreferredNameModel(aiService: AIService): Promise<string | null> {
   for (const modelId of PREFERRED_MODELS) {
-    const result = await aiService.createModel(modelId);
-    if (result.success) {
+    // Try direct provider access first
+    const directResult = await aiService.createModel(modelId);
+    if (directResult.success) {
       return modelId;
     }
-    // If it's an API key error, try the next model; other errors are also skipped
+
+    // Try via mux-gateway (for users without direct provider API keys)
+    const gatewayModelId = toGatewayModel(modelId);
+    const gatewayResult = await aiService.createModel(gatewayModelId);
+    if (gatewayResult.success) {
+      return gatewayModelId;
+    }
   }
   return null;
 }