diff --git a/amplifier_module_loop_streaming/__init__.py b/amplifier_module_loop_streaming/__init__.py
index 6927b68..bdc77c1 100644
--- a/amplifier_module_loop_streaming/__init__.py
+++ b/amplifier_module_loop_streaming/__init__.py
@@ -267,25 +267,52 @@ async def _execute_stream(
                             "Appended ephemeral injection to last tool result message"
                         )
                     else:
-                        # Fall back to new message if last message isn't a tool result
+                        # Fall back: merge if same role, else new message
+                        if last_msg.get("role") == result.context_injection_role:
+                            original_content = last_msg.get("content", "")
+                            message_dicts[-1] = {
+                                **last_msg,
+                                "content": f"{original_content}\n\n{result.context_injection}",
+                            }
+                            logger.debug(
+                                "Merged ephemeral injection into last message (same role: %s)",
+                                result.context_injection_role,
+                            )
+                        else:
+                            message_dicts.append(
+                                {
+                                    "role": result.context_injection_role,
+                                    "content": result.context_injection,
+                                }
+                            )
+                            logger.debug(
+                                f"Last message role is '{last_msg.get('role')}', not 'tool' - "
+                                "created new message for injection"
+                            )
+                else:
+                    # Structural prevention: merge into last message if same role
+                    # to avoid consecutive messages with the same role (confuses models)
+                    if (
+                        len(message_dicts) > 0
+                        and message_dicts[-1].get("role") == result.context_injection_role
+                    ):
+                        last_msg = message_dicts[-1]
+                        original_content = last_msg.get("content", "")
+                        message_dicts[-1] = {
+                            **last_msg,
+                            "content": f"{original_content}\n\n{result.context_injection}",
+                        }
+                        logger.debug(
+                            "Merged ephemeral injection into last message (same role: %s)",
+                            result.context_injection_role,
+                        )
+                    else:
                         message_dicts.append(
                             {
                                 "role": result.context_injection_role,
                                 "content": result.context_injection,
                             }
                         )
-                        logger.debug(
-                            f"Last message role is '{last_msg.get('role')}', not 'tool' - "
-                            "created new message for injection"
-                        )
-                else:
-                    # Default behavior: append as new message
-                    message_dicts.append(
-                        {
-                            "role": result.context_injection_role,
-                            "content": result.context_injection,
-                        }
-                    )
 
             # Apply pending ephemeral injections from tool:post hooks
             if self._pending_ephemeral_injections:
@@ -305,22 +332,50 @@ async def _execute_stream(
                                 "Applied pending ephemeral injection to last tool result"
                             )
                         else:
-                            message_dicts.append(
-                                {
-                                    "role": injection["role"],
-                                    "content": injection["content"],
+                            # Merge if same role as last message
+                            if last_msg.get("role") == injection["role"]:
+                                original_content = last_msg.get("content", "")
+                                message_dicts[-1] = {
+                                    **last_msg,
+                                    "content": f"{original_content}\n\n{injection['content']}",
                                 }
+                                logger.debug(
+                                    "Merged pending injection into last message (same role: %s)",
+                                    injection["role"],
+                                )
+                            else:
+                                message_dicts.append(
+                                    {
+                                        "role": injection["role"],
+                                        "content": injection["content"],
+                                    }
+                                )
+                                logger.debug(
+                                    "Last message not a tool result, created new message for injection"
+                                )
+                    else:
+                        # Structural prevention: merge if same role as last message
+                        if (
+                            len(message_dicts) > 0
+                            and message_dicts[-1].get("role") == injection["role"]
+                        ):
+                            last_msg = message_dicts[-1]
+                            original_content = last_msg.get("content", "")
+                            message_dicts[-1] = {
+                                **last_msg,
+                                "content": f"{original_content}\n\n{injection['content']}",
+                            }
+                            logger.debug(
+                                "Merged pending ephemeral injection into last message (same role: %s)",
+                                injection["role"],
+                            )
+                        else:
+                            message_dicts.append(
+                                {"role": injection["role"], "content": injection["content"]}
                             )
                             logger.debug(
-                                "Last message not a tool result, created new message for injection"
+                                "Applied pending ephemeral injection as new message"
                             )
-                    else:
-                        message_dicts.append(
-                            {"role": injection["role"], "content": injection["content"]}
-                        )
-                        logger.debug(
-                            "Applied pending ephemeral injection as new message"
-                        )
                 # Clear pending injections after applying
                 self._pending_ephemeral_injections = []
 
@@ -669,16 +724,27 @@ async def _execute_stream(
             # Get one final response with the reminder (via _execute_stream helper)
             message_dicts = await context.get_messages_for_request(provider=provider)
             message_dicts = list(message_dicts)
-            message_dicts.append(
-                {
-                    "role": "user",
-                    "content": """<system-reminder source="orchestrator-loop-limit">
+            # Merge loop-limit reminder into last message if same role,
+            # to avoid consecutive user messages that confuse role attribution
+            _loop_limit_content = """<system-reminder source="orchestrator-loop-limit">
 You have reached the maximum number of iterations for this turn. Please provide a response to the user now, summarizing your progress and noting what remains to be done. You can continue in the next turn if needed.
 
 DO NOT mention this iteration limit or reminder to the user explicitly. Simply wrap up naturally.
-</system-reminder>""",
+</system-reminder>"""
+            if (
+                len(message_dicts) > 0
+                and message_dicts[-1].get("role") == "user"
+            ):
+                last_msg = message_dicts[-1]
+                original_content = last_msg.get("content", "")
+                message_dicts[-1] = {
+                    **last_msg,
+                    "content": f"{original_content}\n\n{_loop_limit_content}",
                 }
-            )
+            else:
+                message_dicts.append(
+                    {"role": "user", "content": _loop_limit_content}
+                )
 
             try:
                 # Convert dicts to ChatRequest