fix(02-02): remove multiple category params causing 400 error

fal.ai API only accepts a single category parameter, but we were
sending multiple categories. Now we fetch all active models and
filter client-side using the existing isRelevantModel() function.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/app/api/providers/fal/models/route.ts

@@ -80,13 +80,6 @@ function mapToProviderModel(model: FalModel): ProviderModel {
   };
 }
 
-/**
- * Build category filter query string for relevant categories
- */
-function buildCategoryFilter(): string {
-  return RELEVANT_CATEGORIES.map((cat) => `category=${encodeURIComponent(cat)}`).join("&");
-}
-
 interface ModelsSuccessResponse {
   success: true;
   models: ProviderModel[];
@@ -126,8 +119,9 @@ export async function GET(
   );
 
   try {
-    // Build URL with category filter and optional search
-    let url = `${FAL_API_BASE}/models?${buildCategoryFilter()}&status=active`;
+    // Build URL - fetch all active models, filter client-side
+    // Note: fal.ai API only accepts single category param, so we fetch all and filter
+    let url = `${FAL_API_BASE}/models?status=active`;
 
     if (searchQuery) {
       url += `&q=${encodeURIComponent(searchQuery)}`;

src/lib/providers/fal.ts

@@ -137,13 +137,6 @@ function buildHeaders(apiKey: string | null): HeadersInit {
   return headers;
 }
 
-/**
- * Build category filter query string for relevant categories
- */
-function buildCategoryFilter(): string {
-  return RELEVANT_CATEGORIES.map((cat) => `category=${encodeURIComponent(cat)}`).join("&");
-}
-
 /**
  * fal.ai provider implementation
  */
@@ -155,8 +148,9 @@ const falProvider: ProviderInterface = {
     const apiKey = getApiKeyFromStorage();
 
     try {
-      // Fetch models with category filter for relevant types
-      const url = `${FAL_API_BASE}/models?${buildCategoryFilter()}&status=active`;
+      // Fetch all active models, filter client-side
+      // Note: fal.ai API only accepts single category param, so we fetch all and filter
+      const url = `${FAL_API_BASE}/models?status=active`;
       const response = await fetch(url, {
         headers: buildHeaders(apiKey),
       });
@@ -179,8 +173,9 @@ const falProvider: ProviderInterface = {
     const apiKey = getApiKeyFromStorage();
 
     try {
-      // Search with query and category filter
-      const url = `${FAL_API_BASE}/models?q=${encodeURIComponent(query)}&${buildCategoryFilter()}&status=active`;
+      // Search with query, filter client-side
+      // Note: fal.ai API only accepts single category param, so we fetch all and filter
+      const url = `${FAL_API_BASE}/models?q=${encodeURIComponent(query)}&status=active`;
       const response = await fetch(url, {
         headers: buildHeaders(apiKey),
       });