🤖 refactor: flatten OpenRouter provider config (remove nested 'provider' key)

- Support both flat and nested config formats for backwards compatibility
- New flat format: { order: [...], allow_fallbacks: false }
- Old nested format: { provider: { order: [...], ... } } still works
- Update docs to show simpler flat format
- Routing options automatically wrapped under 'provider' for API

Resolves unnecessary nesting in user configuration.

Author: ammar-agent

docs/models.md

@@ -60,10 +60,8 @@ OpenRouter can route requests to specific infrastructure providers (Cerebras, Fi
   "openrouter": {
     "apiKey": "sk-or-v1-...",
     // Use Cerebras for ultra-fast inference
-    "provider": {
-      "order": ["Cerebras", "Fireworks"],  // Try in order
-      "allow_fallbacks": true               // Allow other providers if unavailable
-    }
+    "order": ["Cerebras", "Fireworks"],  // Try in order
+    "allow_fallbacks": true               // Allow other providers if unavailable
   }
 }
 ```
@@ -74,10 +72,8 @@ Or require a specific provider (no fallbacks):
 {
   "openrouter": {
     "apiKey": "sk-or-v1-...",
-    "provider": {
-      "order": ["Cerebras"],      // Only try Cerebras
-      "allow_fallbacks": false    // Fail if Cerebras unavailable
-    }
+    "order": ["Cerebras"],        // Only try Cerebras
+    "allow_fallbacks": false      // Fail if Cerebras unavailable
   }
 }
 ```
@@ -93,6 +89,8 @@ Or require a specific provider (no fallbacks):
 
 See [OpenRouter Provider Routing docs](https://openrouter.ai/docs/features/provider-routing) for details.
 
+**Note:** The old nested format with `"provider": { ... }` is still supported for backwards compatibility.
+
 **Reasoning Models:**
 
 OpenRouter supports reasoning models like Claude Sonnet Thinking. Use the thinking slider to control reasoning effort:

src/services/aiService.ts

@@ -432,9 +432,50 @@ export class AIService extends EventEmitter {
             : defaultFetchWithUnlimitedTimeout;
 
         // Extract standard provider settings (apiKey, baseUrl, headers, fetch)
-        // and move everything else to extraBody for transparent pass-through
         const { apiKey, baseUrl, headers, fetch: _fetch, ...extraOptions } = providerConfig;
 
+        // OpenRouter routing options that need to be nested under "provider" in API request
+        // See: https://openrouter.ai/docs/features/provider-routing
+        const OPENROUTER_ROUTING_OPTIONS = [
+          "order",
+          "allow_fallbacks",
+          "only",
+          "ignore",
+          "require_parameters",
+          "data_collection",
+          "sort",
+          "quantizations",
+        ];
+
+        // Build extraBody, supporting both flat and nested config formats
+        let extraBody: Record<string, unknown> | undefined;
+
+        if ("provider" in extraOptions && typeof extraOptions.provider === "object") {
+          // Old nested format: { provider: { order: [...], ... } }
+          // Pass through as-is for backwards compatibility
+          extraBody = extraOptions;
+        } else {
+          // New flat format: { order: [...], allow_fallbacks: false, ... }
+          // Restructure: routing options go under "provider", others stay at root
+          const routingOptions: Record<string, unknown> = {};
+          const otherOptions: Record<string, unknown> = {};
+
+          for (const [key, value] of Object.entries(extraOptions)) {
+            if (OPENROUTER_ROUTING_OPTIONS.includes(key)) {
+              routingOptions[key] = value;
+            } else {
+              otherOptions[key] = value;
+            }
+          }
+
+          // Build extraBody with provider nesting if routing options exist
+          if (Object.keys(routingOptions).length > 0) {
+            extraBody = { provider: routingOptions, ...otherOptions };
+          } else if (Object.keys(otherOptions).length > 0) {
+            extraBody = otherOptions;
+          }
+        }
+
         // Lazy-load OpenRouter provider to reduce startup time
         const { createOpenRouter } = await import("@openrouter/ai-sdk-provider");
         const provider = createOpenRouter({
@@ -443,8 +484,7 @@ export class AIService extends EventEmitter {
           headers: headers as Record<string, string> | undefined,
           // eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/no-unsafe-assignment
           fetch: baseFetch as any,
-          // Pass all additional config options (like provider routing) via extraBody
-          extraBody: Object.keys(extraOptions).length > 0 ? extraOptions : undefined,
+          extraBody,
         });
         return Ok(provider(modelId));
       }