diff --git a/opus_orchestrator/agents/base.py b/opus_orchestrator/agents/base.py
index b456a47..e44dcfc 100644
--- a/opus_orchestrator/agents/base.py
+++ b/opus_orchestrator/agents/base.py
@@ -93,6 +93,49 @@ class BaseAgent(ABC, Generic[T]):
             temperature=temp,
             max_tokens=self.config.max_tokens,
         )
+    def validate_output(self, output: Any, schema: type[T]) -> tuple[bool, Optional[T], Optional[str]]:
+        """Validate agent output against a Pydantic schema.
+        
+        Args:
+            output: Raw output from the agent (usually str)
+            schema: Pydantic model to validate against
+            
+        Returns:
+            Tuple of (is_valid, validated_output, error_message)
+        """
+        if schema is None:
+            # No schema to validate against
+            return True, None, None
+        
+        # Try to parse the output as the schema
+        try:
+            # If output is a string, try to parse as JSON first
+            if isinstance(output, str):
+                import json
+                # Try to extract JSON from the output
+                try:
+                    # Look for JSON block
+                    if "```json" in output:
+                        json_str = output.split("```json")[1].split("```")[0]
+                    elif "```" in output:
+                        json_str = output.split("```")[1].split("```")[0]
+                    else:
+                        json_str = output
+                    data = json.loads(json_str)
+                except (json.JSONDecodeError, IndexError):
+                    # Not JSON, return as-is
+                    return True, None, None
+            else:
+                data = output
+            
+            # Validate against schema
+            validated = schema(**data)
+            return True, validated, None
+            
+        except Exception as e:
+            return False, None, f"Validation failed: {str(e)}"
+
+
 
     def build_system_prompt(self, context: dict[str, Any]) -> str:
         """Build the full system prompt with context.
diff --git a/opus_orchestrator/state_adapter.py b/opus_orchestrator/state_adapter.py
new file mode 100644
index 0000000..8965d97
--- /dev/null
+++ b/opus_orchestrator/state_adapter.py
@@ -0,0 +1,134 @@
+"""Unified State Adapter for Opus Orchestrator.
+
+Provides adapters between OpusState and OpusGraphState to unify
+the two state systems.
+"""
+
+from typing import Any, Optional
+
+from opus_orchestrator.state import OpusState
+from opus_orchestrator.langgraph_state import OpusGraphState
+
+
+class StateAdapter:
+    """Adapter to convert between OpusState and OpusGraphState."""
+    
+    @staticmethod
+    def opus_to_graph(opus_state: OpusState) -> dict[str, Any]:
+        """Convert OpusState to dict for OpusGraphState.
+        
+        Args:
+            opus_state: The OpusState to convert
+            
+        Returns:
+            Dict suitable for creating OpusGraphState
+        """
+        # Extract pre-writing data if available
+        prewriting_data = {}
+        
+        if opus_state.blueprint:
+            prewriting_data = {
+                "one_sentence": opus_state.blueprint.title,  # Approximate
+                "one_paragraph": opus_state.blueprint.subtitle or "",
+            }
+        
+        return {
+            "seed_concept": opus_state.raw_content.text[:500] if opus_state.raw_content else "",
+            "framework": "snowflake",
+            "genre": opus_state.intent.genre if opus_state.intent else "general",
+            "target_word_count": opus_state.intent.target_word_count if opus_state.intent else 80000,
+            "prewriting": prewriting_data,
+        }
+    
+    @staticmethod
+    def graph_to_opus(graph_state: OpusGraphState) -> OpusState:
+        """Convert OpusGraphState back to OpusState.
+        
+        This is lossy - only preserves key fields.
+        
+        Args:
+            graph_state: The OpusGraphState to convert
+            
+        Returns:
+            OpusState with available data
+        """
+        from opus_orchestrator.schemas import BookIntent, BookType
+        
+        intent = BookIntent(
+            book_type=BookType.FICTION,
+            genre=graph_state.genre,
+            target_word_count=graph_state.target_word_count,
+            target_audience="general readers",
+            intended_outcome="complete novel",
+        )
+        
+        opus_state = OpusState(
+            intent=intent,
+            current_stage=graph_state.stage.value,
+            progress=graph_state.progress,
+        )
+        
+        # Add manuscript if available
+        if graph_state.manuscript:
+            from opus_orchestrator.schemas import Manuscript, Chapter
+            chapters = []
+            for i, ch_state in graph_state.chapters.items():
+                chapters.append(Chapter(
+                    chapter_number=i,
+                    title=ch_state.content[:50],
+                    content=ch_state.content,
+                    word_count=ch_state.word_count,
+                ))
+            
+            opus_state.manuscript = Manuscript(
+                title="Untitled",
+                book_type=BookType.FICTION,
+                genre=graph_state.genre,
+                chapters=chapters,
+                total_word_count=graph_state.total_word_count,
+            )
+        
+        return opus_state
+    
+    @staticmethod
+    def create_unified_state(
+        seed_concept: str,
+        framework: str = "snowflake",
+        genre: str = "general",
+        target_word_count: int = 80000,
+    ) -> dict[str, Any]:
+        """Create initial state dict that works for both systems.
+        
+        Args:
+            seed_concept: The seed concept for the book
+            framework: Story framework to use
+            genre: Genre of the book
+            target_word_count: Target word count
+            
+        Returns:
+            Dict that can initialize either state model
+        """
+        return {
+            # Common fields
+            "seed_concept": seed_concept,
+            "framework": framework,
+            "genre": genre,
+            "target_word_count": target_word_count,
+            # For OpusState compatibility
+            "repo_url": None,
+            "intent": None,
+            "raw_content": None,
+            # For OpusGraphState compatibility
+            "prewriting": {},
+            "style_guide": "",
+            "current_chapter": 0,
+            "chapters": {},
+            "manuscript": "",
+            "total_word_count": 0,
+            "use_autogen": True,
+            "critique_iterations": {},
+            "validation_errors": [],
+            "warnings": [],
+            "progress": 0.0,
+            "messages": [],
+        }