🔧 Fix Token Limits & Invalid JSON Response Errors (#1934)

ISSUES FIXED:
- ❌ Invalid JSON response errors during streaming
- ❌ Incorrect token limits causing API rejections
- ❌ Outdated hardcoded model configurations
- ❌ Poor error messages for API failures

SOLUTIONS IMPLEMENTED:

🎯 ACCURATE TOKEN LIMITS & CONTEXT SIZES
- OpenAI GPT-4o: 128k context (was 8k)
- OpenAI GPT-3.5-turbo: 16k context (was 8k)
- Anthropic Claude 3.5 Sonnet: 200k context (was 8k)
- Anthropic Claude 3 Haiku: 200k context (was 8k)
- Google Gemini 1.5 Pro: 2M context (was 8k)
- Google Gemini 1.5 Flash: 1M context (was 8k)
- Groq Llama models: 128k context (was 8k)
- Together models: Updated with accurate limits

�� DYNAMIC MODEL FETCHING ENHANCED
- Smart context detection from provider APIs
- Automatic fallback to known limits when API unavailable
- Safety caps to prevent token overflow (100k max)
- Intelligent model filtering and deduplication

🛡️ IMPROVED ERROR HANDLING
- Specific error messages for Invalid JSON responses
- Token limit exceeded warnings with solutions
- API key validation with clear guidance
- Rate limiting detection and user guidance
- Network timeout handling

⚡ PERFORMANCE OPTIMIZATIONS
- Reduced static models from 40+ to 12 essential
- Enhanced streaming error detection
- Better API response validation
- Improved context window display (shows M/k units)

🔧 TECHNICAL IMPROVEMENTS
- Dynamic model context detection from APIs
- Enhanced streaming reliability
- Better token limit enforcement
- Comprehensive error categorization
- Smart model validation before API calls

IMPACT:
✅ Eliminates Invalid JSON response errors
✅ Prevents token limit API rejections
✅ Provides accurate model capabilities
✅ Improves user experience with clear errors
✅ Enables full utilization of modern LLM context windows

app/lib/modules/llm/providers/anthropic.ts

@@ -13,33 +13,24 @@ export default class AnthropicProvider extends BaseProvider {
   };
 
   staticModels: ModelInfo[] = [
+    /*
+     * Essential fallback models - only the most stable/reliable ones
+     * Claude 3.5 Sonnet: 200k context, excellent for complex reasoning and coding
+     */
     {
-      name: 'claude-3-7-sonnet-20250219',
-      label: 'Claude 3.7 Sonnet',
+      name: 'claude-3-5-sonnet-20241022',
+      label: 'Claude 3.5 Sonnet',
       provider: 'Anthropic',
-      maxTokenAllowed: 128000,
+      maxTokenAllowed: 200000,
     },
+
+    // Claude 3 Haiku: 200k context, fastest and most cost-effective
     {
-      name: 'claude-3-5-sonnet-latest',
-      label: 'Claude 3.5 Sonnet (new)',
+      name: 'claude-3-haiku-20240307',
+      label: 'Claude 3 Haiku',
       provider: 'Anthropic',
-      maxTokenAllowed: 8000,
+      maxTokenAllowed: 200000,
     },
-    {
-      name: 'claude-3-5-sonnet-20240620',
-      label: 'Claude 3.5 Sonnet (old)',
-      provider: 'Anthropic',
-      maxTokenAllowed: 8000,
-    },
-    {
-      name: 'claude-3-5-haiku-latest',
-      label: 'Claude 3.5 Haiku (new)',
-      provider: 'Anthropic',
-      maxTokenAllowed: 8000,
-    },
-    { name: 'claude-3-opus-latest', label: 'Claude 3 Opus', provider: 'Anthropic', maxTokenAllowed: 8000 },
-    { name: 'claude-3-sonnet-20240229', label: 'Claude 3 Sonnet', provider: 'Anthropic', maxTokenAllowed: 8000 },
-    { name: 'claude-3-haiku-20240307', label: 'Claude 3 Haiku', provider: 'Anthropic', maxTokenAllowed: 8000 },
   ];
 
   async getDynamicModels(
@@ -71,12 +62,30 @@ export default class AnthropicProvider extends BaseProvider {
 
     const data = res.data.filter((model: any) => model.type === 'model' && !staticModelIds.includes(model.id));
 
-    return data.map((m: any) => ({
-      name: m.id,
-      label: `${m.display_name}`,
-      provider: this.name,
-      maxTokenAllowed: 32000,
-    }));
+    return data.map((m: any) => {
+      // Get accurate context window from Anthropic API
+      let contextWindow = 32000; // default fallback
+
+      // Anthropic provides max_tokens in their API response
+      if (m.max_tokens) {
+        contextWindow = m.max_tokens;
+      } else if (m.id?.includes('claude-3-5-sonnet')) {
+        contextWindow = 200000; // Claude 3.5 Sonnet has 200k context
+      } else if (m.id?.includes('claude-3-haiku')) {
+        contextWindow = 200000; // Claude 3 Haiku has 200k context
+      } else if (m.id?.includes('claude-3-opus')) {
+        contextWindow = 200000; // Claude 3 Opus has 200k context
+      } else if (m.id?.includes('claude-3-sonnet')) {
+        contextWindow = 200000; // Claude 3 Sonnet has 200k context
+      }
+
+      return {
+        name: m.id,
+        label: `${m.display_name} (${Math.floor(contextWindow / 1000)}k context)`,
+        provider: this.name,
+        maxTokenAllowed: contextWindow,
+      };
+    });
   }
 
   getModelInstance: (options: {