Improve error messages for invalid Bedrock model IDs

llm.py

@@ -141,7 +141,14 @@ def chat(messages, persona):
             raise
         except Exception as e:
             error_msg = str(e)
-            if "UnrecognizedClientException" in error_msg or "invalid" in error_msg.lower():
+            if "ValidationException" in error_msg and "model identifier is invalid" in error_msg:
+                raise ValueError(
+                    f"Invalid Bedrock model ID: '{MODEL_STRING}'. "
+                    f"Error: {error_msg}. "
+                    "Please verify the model ID is correct and the model is available in your AWS region. "
+                    "Common Claude model IDs: 'anthropic.claude-3-5-sonnet-20241022-v2' or 'anthropic.claude-3-haiku-20240307-v1'"
+                ) from e
+            elif "UnrecognizedClientException" in error_msg or "invalid" in error_msg.lower():
                 raise ValueError(
                     f"AWS Bedrock authentication failed: {error_msg}. "
                     "Please verify your AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY secrets "
@@ -201,7 +208,13 @@ def chat(messages, persona):
             raise
         except Exception as e:
             error_msg = str(e)
-            if "UnrecognizedClientException" in error_msg or "invalid" in error_msg.lower():
+            if "ValidationException" in error_msg and "model identifier is invalid" in error_msg:
+                raise ValueError(
+                    f"Invalid Bedrock model ID: '{MODEL_STRING}'. "
+                    f"Error: {error_msg}. "
+                    "Please verify the model ID is correct and the model is available in your AWS region."
+                ) from e
+            elif "UnrecognizedClientException" in error_msg or "invalid" in error_msg.lower():
                 raise ValueError(
                     f"AWS Bedrock authentication failed: {error_msg}. "
                     "Please verify your AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY secrets "