fix: Builder state

Author: tmathern

src/c2pa/c2pa.py

@@ -2079,6 +2079,7 @@ def __init__(self, manifest_json: Any):
             C2paError.Json: If the manifest JSON cannot be serialized
         """
         self._closed = False
+        self._initialized = False
         self._builder = None
 
         if not isinstance(manifest_json, str):
@@ -2108,6 +2109,9 @@ def __init__(self, manifest_json: Any):
                 )
             )
 
+        # Mark as initialized only after successful creation
+        self._initialized = True
+
     @classmethod
     def from_json(cls, manifest_json: Any) -> 'Builder':
         """Create a new Builder from a JSON manifest.
@@ -2150,16 +2154,20 @@ def from_archive(cls, stream: Any) -> 'Builder':
                 raise C2paError(error)
             raise C2paError("Failed to create builder from archive")
 
+        # Mark as initialized after successful creation from archive
+        builder._initialized = True
         return builder
 
     def _ensure_valid_state(self):
         """Ensure the builder is in a valid state for operations.
 
         Raises:
-            C2paError: If the builder is closed or invalid
+            C2paError: If the builder is closed, not initialized, or invalid
         """
         if self._closed:
             raise C2paError(Builder._ERROR_MESSAGES['closed_error'])
+        if not self._initialized:
+            raise C2paError("Builder is not properly initialized")
         if not self._builder:
             raise C2paError(Builder._ERROR_MESSAGES['closed_error'])
 
@@ -2187,6 +2195,9 @@ def _cleanup_resources(self):
                         pass
                     finally:
                         self._builder = None
+
+                # Reset initialized state after cleanup
+                self._initialized = False
         except Exception:
             # Ensure we don't raise exceptions during cleanup
             pass
@@ -2219,10 +2230,6 @@ def close(self):
 
     def __enter__(self):
         self._ensure_valid_state()
-
-        if not self._builder:
-            raise C2paError("Invalid Builder when entering context")
-
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
@@ -2327,8 +2334,7 @@ def add_ingredient_from_stream(
             C2paError.Encoding: If the ingredient JSON or format
               contains invalid UTF-8 characters
         """
-        if not self._builder:
-            raise C2paError(Builder._ERROR_MESSAGES['closed_error'])
+        self._ensure_valid_state()
 
         try:
             ingredient_str = ingredient_json.encode('utf-8')
@@ -2413,8 +2419,7 @@ def to_archive(self, stream: Any) -> None:
         Raises:
             C2paError: If there was an error writing the archive
         """
-        if not self._builder:
-            raise C2paError(Builder._ERROR_MESSAGES['closed_error'])
+        self._ensure_valid_state()
 
         with Stream(stream) as stream_obj:
             result = _lib.c2pa_builder_to_archive(
@@ -2452,8 +2457,7 @@ def _sign_internal(
         Raises:
             C2paError: If there was an error during signing
         """
-        if not self._builder:
-            raise C2paError(Builder._ERROR_MESSAGES['closed_error'])
+        self._ensure_valid_state()
 
         # Validate signer pointer before use
         if not signer or not hasattr(signer, '_signer') or not signer._signer: