feat: add OpenRouter as an AI provider (AIIA-86)

Integrate OpenRouter via its OpenAI-compatible API so users can select
and use OpenRouter models alongside existing Anthropic/OpenAI/Ollama
providers. Adds provider to type system, DB enum, API validation,
buildModel switch, and settings UI.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

drizzle/0004_add_openrouter_provider.sql

@@ -0,0 +1,2 @@
+-- Add 'openrouter' to the api_key_provider enum
+ALTER TYPE "api_key_provider" ADD VALUE IF NOT EXISTS 'openrouter';

src/app/(dashboard)/einstellungen/ai-settings.tsx

@@ -91,6 +91,7 @@ export default function AISettingsForm() {
           >
             <option value="anthropic">Anthropic (Claude)</option>
             <option value="openai">OpenAI (GPT)</option>
+            <option value="openrouter">OpenRouter</option>
             <option value="ollama">Ollama (Lokal)</option>
           </select>
         </div>
@@ -103,7 +104,7 @@ export default function AISettingsForm() {
                 type="text"
                 value={settings.model}
                 onChange={(e) => setSettings({ ...settings, model: e.target.value })}
-                placeholder={settings.provider === 'anthropic' ? 'claude-sonnet-4-20250514' : 'gpt-4o'}
+                placeholder={settings.provider === 'anthropic' ? 'claude-sonnet-4-20250514' : settings.provider === 'openrouter' ? 'anthropic/claude-sonnet-4' : 'gpt-4o'}
                 className="w-full rounded-lg border border-card-border bg-background px-3 py-2 text-sm text-foreground placeholder:text-muted/50"
               />
             </div>
@@ -111,7 +112,7 @@ export default function AISettingsForm() {
               const activeKey = apiKeys.find(
                 (k) => k.provider === settings.provider && k.isActive,
               );
-              const providerLabel = settings.provider === 'anthropic' ? 'Anthropic' : 'OpenAI';
+              const providerLabel = settings.provider === 'anthropic' ? 'Anthropic' : settings.provider === 'openrouter' ? 'OpenRouter' : 'OpenAI';
 
               async function handleSaveApiKey() {
                 if (!apiKeyInput || apiKeyInput.length < 8) {

src/app/(dashboard)/einstellungen/api-key-settings.tsx

@@ -14,6 +14,7 @@ interface ApiKeyEntry {
 const PROVIDER_LABELS: Record<string, string> = {
   anthropic: 'Anthropic',
   openai: 'OpenAI',
+  openrouter: 'OpenRouter',
   ollama: 'Ollama',
 };
 
@@ -172,6 +173,7 @@ export default function ApiKeySettings() {
             >
               <option value="anthropic">Anthropic</option>
               <option value="openai">OpenAI</option>
+              <option value="openrouter">OpenRouter</option>
             </select>
           </div>
           <div>

src/app/api/settings/ai/route.ts

@@ -7,7 +7,7 @@ import { eq } from 'drizzle-orm';
 import { requirePermission } from '@/lib/auth/rbac';
 import type { AIProvider } from '@/lib/ai/providers';
 
-const VALID_PROVIDERS = new Set<AIProvider>(['anthropic', 'openai', 'ollama']);
+const VALID_PROVIDERS = new Set<AIProvider>(['anthropic', 'openai', 'openrouter', 'ollama']);
 
 export async function GET() {
   const auth = await requirePermission('settings:manage');

src/app/api/settings/api-keys/route.ts

@@ -9,7 +9,7 @@ import { encrypt, keyHint } from '@/lib/crypto';
 import { logAuditEvent } from '@/lib/auth/audit';
 import type { AIProvider } from '@/lib/ai/providers';
 
-const VALID_PROVIDERS = new Set<AIProvider>(['anthropic', 'openai', 'ollama']);
+const VALID_PROVIDERS = new Set<AIProvider>(['anthropic', 'openai', 'openrouter', 'ollama']);
 
 export async function GET() {
   const auth = await requirePermission('settings:manage');

src/lib/ai/providers/index.ts

@@ -1,5 +1,5 @@
 // AI Provider abstraction via Vercel AI SDK v6
-// Supports: Anthropic, OpenAI, Ollama — selected via AI_PROVIDER env var or tenant settings
+// Supports: Anthropic, OpenAI, OpenRouter, Ollama — selected via AI_PROVIDER env var or tenant settings
 // Per-tenant API keys are loaded from tenant_api_keys (AES-256-GCM encrypted)
 
 import { createAnthropic, anthropic } from '@ai-sdk/anthropic';
@@ -10,17 +10,19 @@ import { tenants, tenantApiKeys } from '@/lib/db/schema';
 import { eq, and } from 'drizzle-orm';
 import { decrypt } from '@/lib/crypto';
 
-export type AIProvider = 'anthropic' | 'openai' | 'ollama';
+export type AIProvider = 'anthropic' | 'openai' | 'openrouter' | 'ollama';
 
 const DEFAULT_MODELS: Record<AIProvider, string> = {
   anthropic: 'claude-sonnet-4-20250514',
   openai: 'gpt-4o',
+  openrouter: 'anthropic/claude-sonnet-4',
   ollama: 'llama3',
 };
 
 export function getProvider(): AIProvider {
   const p = process.env.AI_PROVIDER;
   if (p === 'openai') return 'openai';
+  if (p === 'openrouter') return 'openrouter';
   if (p === 'ollama') return 'ollama';
   return 'anthropic';
 }
@@ -45,6 +47,13 @@ function buildModel(
       }
       return openai(modelId);
     }
+    case 'openrouter': {
+      const openrouter = createOpenAI({
+        baseURL: 'https://openrouter.ai/api/v1',
+        apiKey: options?.apiKey ?? process.env.OPENROUTER_API_KEY ?? '',
+      });
+      return openrouter(modelId);
+    }
     case 'ollama': {
       const baseURL = options?.ollamaUrl ?? process.env.OLLAMA_URL ?? 'http://localhost:11434';
       const ollama = createOpenAI({
@@ -97,7 +106,7 @@ export async function getModelForTenant(tenantId: string): Promise<{ model: Lang
     .limit(1);
 
   const s = tenant?.settings as Record<string, string> | undefined;
-  const provider: AIProvider = (['anthropic', 'openai', 'ollama'].includes(s?.aiProvider ?? '') ? s!.aiProvider : getProvider()) as AIProvider;
+  const provider: AIProvider = (['anthropic', 'openai', 'openrouter', 'ollama'].includes(s?.aiProvider ?? '') ? s!.aiProvider : getProvider()) as AIProvider;
 
   let modelId: string;
   if (provider === 'ollama') {

src/lib/db/schema.ts

@@ -977,6 +977,7 @@ export const documents = pgTable(
 export const apiKeyProviderEnum = pgEnum("api_key_provider", [
   "anthropic",
   "openai",
+  "openrouter",
   "ollama",
 ]);