diff --git a/models.py b/models.py
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+++ b/models.py
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+"""
+Shared data structures for the Planning Agent.
+
+The module contains a TypedDict that represents the state used by LangGraph.
+It is imported in ``main.py`` to keep type hints consistent across files.
+"""
+
+from typing import List, TypedDict
+
+class PlanningState(TypedDict):
+    """State of the planning agent.
+
+    Attributes:
+        task: The original natural‑language description.
+        plan: Optional list of steps produced by the LLM.
+        current_step: Index of the next step to execute.
+        results: Accumulated textual results for each executed step.
+    """
+
+    task: str
+    plan: List[str] | None
+    current_step: int
+    results: List[str]