Fix model config alignment and improve error messaging

- Replace sys.exit(1) with ValueError in _validate_models() — prevents killing the worker process on invalid model keys
- ModelConfiguration now reads defaults from core.config instead of hardcoding model keys
- Fix .env: google-gemini20 → google-gemini31 (align with MODEL_MAPPINGS)
- Improve "No data extracted" error message to explain the document must be a marketing brief

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/core/process_brief_enhanced.py

@@ -439,13 +439,11 @@ class DocumentAnalyzer:
         # Validate primary models
         for model in self.primary_models:
             if model not in valid_models:
-                logging.error(f"Invalid primary model: {model}. Available: {valid_models}")
-                sys.exit(1)
-        
-        # Validate consolidation model  
+                raise ValueError(f"Invalid primary model: {model}. Available: {valid_models}")
+
+        # Validate consolidation model
         if self.consolidation_model not in valid_models:
-            logging.error(f"Invalid consolidation model: {self.consolidation_model}. Available: {valid_models}")
-            sys.exit(1)
+            raise ValueError(f"Invalid consolidation model: {self.consolidation_model}. Available: {valid_models}")
             
         # Validate API keys
         api_key_status = config.validate_api_keys()

backend/server/jobs/models.py

@@ -8,6 +8,20 @@ from enum import Enum
 from typing import Dict, List, Optional, Any
 import uuid
 
+def _default_primary_models() -> List[str]:
+    try:
+        from core.config import config
+        return config.get_default_primary_models()
+    except Exception:
+        return ['anthropic-sonnet45', 'google-gemini31']
+
+def _default_consolidation_model() -> str:
+    try:
+        from core.config import config
+        return config.DEFAULT_CONSOLIDATION_MODEL
+    except Exception:
+        return 'anthropic-sonnet45'
+
 class JobPhase(Enum):
     """Processing phases for a job"""
     QUEUED = "QUEUED"
@@ -116,10 +130,8 @@ class ModelInfo:
 @dataclass
 class ModelConfiguration:
     """Model selection configuration for a job"""
-    primary_models: List[str] = field(default_factory=lambda: [
-        'openai-gpt51', 'anthropic-sonnet45', 'google-gemini31'
-    ])
-    consolidation_model: str = 'openai-gpt51'
+    primary_models: List[str] = field(default_factory=_default_primary_models)
+    consolidation_model: str = field(default_factory=_default_consolidation_model)
     minimum_success_threshold: int = 1
 
     def to_dict(self) -> Dict[str, Any]:

backend/server/runners/job_runner.py

@@ -58,7 +58,14 @@ async def run_job(job: Job, ws_manager: WebSocketManager) -> bool:
         result = await analyzer.process_document_multi_model(job.upload_path, progress)
 
         if not result.raw_data:
-            error_msg = "No data extracted from document"
+            notes = "; ".join(result.processing_notes) if result.processing_notes else ""
+            error_msg = (
+                "No marketing deliverables found in this document. "
+                "Please ensure you upload a marketing brief (PDF, PPTX, DOCX, or XLSX) "
+                "containing campaign assets or deliverables."
+            )
+            if notes:
+                error_msg += f" (Details: {notes})"
             await progress.emit_failure(error_msg)
             return False