fix(title): fall back to configured provider for title generation

src/routes/api/title-generator.ts

@@ -1,4 +1,5 @@
 import { createFileRoute } from '@tanstack/react-router';
+
 import { createAnthropicText } from '@/server/anthropic';
 import {
   isRecord,
@@ -10,7 +11,9 @@ import {
 } from '@/server/api';
 
 const TITLE_SYSTEM_PROMPT =
-  'Generate a concise, descriptive title under 80 characters for this CAD conversation. Return only the title. If unclear, return "New Conversation".';
+  'Generate a concise, descriptive title under 80 characters for this ' +
+  'CAD conversation. Return only the title. If unclear, return ' +
+  '"New Conversation".';
 
 function textFromParts(parts: unknown): string {
   if (!Array.isArray(parts)) return '';
@@ -25,6 +28,103 @@ function textFromParts(parts: unknown): string {
     .trim();
 }
 
+function textFromChatCompletion(data: unknown): string | null {
+  if (!isRecord(data)) return null;
+  const choices = data.choices;
+  if (!Array.isArray(choices)) return null;
+  const first: unknown = choices[0];
+  const message = isRecord(first) ? first.message : null;
+  const content = isRecord(message) ? message.content : null;
+  return typeof content === 'string' ? content : null;
+}
+
+function textFromGemini(data: unknown): string | null {
+  if (!isRecord(data)) return null;
+  const candidates = data.candidates;
+  if (!Array.isArray(candidates)) return null;
+  const first: unknown = candidates[0];
+  const content = isRecord(first) ? first.content : null;
+  const parts = isRecord(content) ? content.parts : null;
+  if (!Array.isArray(parts)) return null;
+  const part: unknown = parts[0];
+  const value = isRecord(part) ? part.text : null;
+  return typeof value === 'string' ? value : null;
+}
+
+async function openRouterTitle(text: string): Promise<string | null> {
+  const response = await fetch(
+    'https://openrouter.ai/api/v1/chat/completions',
+    {
+      method: 'POST',
+      headers: {
+        'Content-Type': 'application/json',
+        Authorization: `Bearer ${process.env.OPENROUTER_API_KEY}`,
+      },
+      body: JSON.stringify({
+        model: 'openai/gpt-5.6-sol',
+        max_tokens: 100,
+        messages: [
+          { role: 'system', content: TITLE_SYSTEM_PROMPT },
+          { role: 'user', content: text },
+        ],
+      }),
+    },
+  );
+  if (!response.ok) return null;
+  return textFromChatCompletion(await response.json());
+}
+
+async function googleTitle(text: string): Promise<string | null> {
+  const url =
+    'https://generativelanguage.googleapis.com/v1beta/models/' +
+    'gemini-3.8-flash:generateContent';
+  const response = await fetch(url, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      'x-goog-api-key': process.env.GOOGLE_API_KEY ?? '',
+    },
+    body: JSON.stringify({
+      systemInstruction: { parts: [{ text: TITLE_SYSTEM_PROMPT }] },
+      contents: [{ role: 'user', parts: [{ text }] }],
+      generationConfig: { maxOutputTokens: 100 },
+    }),
+  });
+  if (!response.ok) return null;
+  return textFromGemini(await response.json());
+}
+
+/**
+ * Generate a title with whichever provider is configured.
+ *
+ * Anthropic stays the default (unchanged for the hosted app). A self-hosted
+ * instance configured only with an OpenRouter or Google key would otherwise
+ * get every conversation stuck on "New Conversation", since the previous
+ * implementation always called Anthropic. Fall back to those providers — the
+ * same set the chat supports, where OpenAI models are served through
+ * OpenRouter — when no Anthropic key is set. Returns null when none is set.
+ */
+async function generateTitleText(text: string): Promise<string | null> {
+  if (process.env.ANTHROPIC_API_KEY) {
+    return createAnthropicText({
+      model: 'claude-haiku-4-5-20251001',
+      maxTokens: 100,
+      system: TITLE_SYSTEM_PROMPT,
+      content: text,
+    });
+  }
+
+  if (process.env.OPENROUTER_API_KEY) {
+    return openRouterTitle(text);
+  }
+
+  if (process.env.GOOGLE_API_KEY) {
+    return googleTitle(text);
+  }
+
+  return null;
+}
+
 export const Route = createFileRoute('/api/title-generator')({
   server: {
     handlers: {
@@ -39,23 +139,17 @@ export const Route = createFileRoute('/api/title-generator')({
           }
           throw err;
         }
+
         try {
           const body: unknown = await request.json();
-          if (!isRecord(body)) {
-            return json({ title: 'New Conversation' });
-          }
+          if (!isRecord(body)) return json({ title: 'New Conversation' });
           const trimmedText =
             typeof body.text === 'string' ? body.text.trim() : '';
           const text = trimmedText || textFromParts(body.parts);
           if (!text) return json({ title: 'New Conversation' });
 
-          const title = await createAnthropicText({
-            model: 'claude-haiku-4-5-20251001',
-            maxTokens: 100,
-            system: TITLE_SYSTEM_PROMPT,
-            content: text,
-          });
-          return json({ title: title || 'New Conversation' });
+          const title = await generateTitleText(text);
+          return json({ title: title?.trim() || 'New Conversation' });
         } catch {
           return json({ title: 'New Conversation' });
         }