[Haik]: ckpt, swapped the HaikFix folder to be parallel to the agents folder bc ima start the full replacement process i think

backend/apps/HaikFix/Agent/shared_structs/MessageLog.py

@@ -0,0 +1,51 @@
+from typeguard import typechecked
+from pydantic import BaseModel, Field
+from typing import List
+
+from backend.apps.HaikFix.Agent.shared_structs.Message.Message import AnyMessage
+
+
+class MessageLog(BaseModel):
+    """Ordered log of conversation messages for an Agent.
+
+    Backed by a plain list — optimized for sequential append (the hot path)
+    while still supporting ID-based lookup and slicing for branching.
+    """
+
+    messages: List[AnyMessage] = Field(default_factory=list)
+
+    @typechecked
+    def append(self, msg: AnyMessage) -> None:
+        """Append a message to the end of the log. O(1) amortized."""
+        self.messages.append(msg)
+
+    @typechecked
+    def get(self, message_id: str) -> AnyMessage | None:
+        """Look up a single message by ID.
+
+        Returns None if no message with the given ID exists.
+        O(n) scan — fine for infrequent lookups on conversation-sized data.
+        """
+        return next((m for m in self.messages if m.id == message_id), None)
+
+    @typechecked
+    def slice_to(self, message_id: str) -> List[AnyMessage]:
+        """Return all messages from the start up to and including the given ID.
+
+        Used by Agent.branch() to snapshot the conversation history at a
+        specific fork point. Raises ValueError if the ID isn't found.
+        """
+        for i, m in enumerate[AnyMessage](self.messages):
+            if m.id == message_id:
+                return self._messages[:i + 1]
+        raise ValueError(f"Message {message_id} not found")
+
+    @typechecked
+    def all(self) -> List[AnyMessage]:
+        """Return a shallow copy of the full message list."""
+        return list[AnyMessage](self.messages)
+
+    @typechecked
+    def __len__(self) -> int:
+        """Return the number of messages in the log."""
+        return len(self.messages)