1 files changed, 15 insertions, 0 deletions
diff --git a/src/Agent.Planner/TokenEstimate.cs b/src/Agent.Planner/TokenEstimate.cs
new file mode 100644
index 0000000..4b8920a
--- /dev/null
+++ b/src/Agent.Planner/TokenEstimate.cs
@@ -0,0 +1,15 @@
+namespace Agent.Planner;
+
+public readonly record struct TokenEstimate(long Optimistic, long MostLikely, long Pessimistic)
+{
+    public double ExpectedTokens => (Optimistic + (4d * MostLikely) + Pessimistic) / 6d;
+    public double VarianceTokens => Math.Pow((Pessimistic - Optimistic) / 6d, 2);
+
+    public void Validate(TokenBudgetClass budgetClass)
+    {
+        if (Optimistic <= 0 || Optimistic > MostLikely || MostLikely > Pessimistic || Pessimistic > budgetClass.MaxTokens())
+        {
+            throw new PlannerValidationException("Estimate must satisfy 0 < O <= M <= P <= token budget.");
+        }
+    }
+}