diff --git a/src/dotnet/QuantEngine.Application/Services/FormulaService.cs b/src/dotnet/QuantEngine.Application/Services/FormulaService.cs
index 42813dbb..dbe8e276 100644
--- a/src/dotnet/QuantEngine.Application/Services/FormulaService.cs
+++ b/src/dotnet/QuantEngine.Application/Services/FormulaService.cs
@@ -16,14 +16,14 @@ namespace QuantEngine.Application.Services
             _learningService = learningService;
         }
 
-        public TimingDecisionResult ComputeTimingDecision(Dictionary<string, object> ctx)
-            => FormulaEngine.ComputeTimingDecision(ctx);
+    public TimingDecisionResult ComputeTimingDecision(Dictionary<string, object> ctx)
+            => FormulaEngine.ComputeTimingDecision(RequireContext(ctx));
 
-        public SellDecisionResult ComputeSellDecision(Dictionary<string, object> ctx)
-            => FormulaEngine.ComputeSellDecision(ctx);
+    public SellDecisionResult ComputeSellDecision(Dictionary<string, object> ctx)
+            => FormulaEngine.ComputeSellDecision(RequireContext(ctx));
 
-        public FinalDecisionResult ComputeFinalDecision(Dictionary<string, object> ctx)
-            => FormulaEngine.ComputeFinalDecision(ctx);
+    public FinalDecisionResult ComputeFinalDecision(Dictionary<string, object> ctx)
+            => FormulaEngine.ComputeFinalDecision(RequireContext(ctx));
 
         public async Task<Guid> ComputeAndRecordFinalDecisionAsync(
             Dictionary<string, object> ctx,
@@ -32,17 +32,18 @@ namespace QuantEngine.Application.Services
             string sourceVersion,
             IEnumerable<FactorEvidenceInput> factorEvidence)
         {
-            var decision = ComputeFinalDecision(ctx);
+            var normalizedContext = RequireContext(ctx);
+            var decision = ComputeFinalDecision(normalizedContext);
             return await _learningService.RecordDecisionAsync(
-                decisionKey,
+                RequireValue(decisionKey, nameof(decisionKey)),
                 DateTimeOffset.UtcNow,
-                instrumentId,
+                RequireValue(instrumentId, nameof(instrumentId)),
                 decision.FinalAction,
                 "PASS",
                 Convert.ToDecimal(decision.PriorityScore),
-                sourceVersion,
+                RequireValue(sourceVersion, nameof(sourceVersion)),
                 factorEvidence,
-                new { context_keys = ctx.Keys.OrderBy(key => key).ToArray() },
+                new { context_keys = normalizedContext.Keys.OrderBy(key => key).ToArray() },
                 new { formula = "FormulaEngine.ComputeFinalDecision", source_version = sourceVersion });
         }
 
@@ -59,6 +60,22 @@ namespace QuantEngine.Application.Services
             => FormulaEngine.ComputeCashRecoveryOptimizer(sellCandidates, cashShortfallMinKrw);
 
         public Task<int> AppendFormulaRunAsync(string formulaName, Dictionary<string, object?> payload)
-            => _historyStore.AppendAsync($"formula_{formulaName}_history", payload);
+            => _historyStore.AppendAsync($"formula_{RequireValue(formulaName, nameof(formulaName))}_history", payload);
+
+        private static Dictionary<string, object> RequireContext(Dictionary<string, object> ctx)
+        {
+            ArgumentNullException.ThrowIfNull(ctx);
+            return ctx;
+        }
+
+        private static string RequireValue(string value, string parameterName)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                throw new ArgumentException("Value is required.", parameterName);
+            }
+
+            return value.Trim();
+        }
     }
 }
diff --git a/src/dotnet/QuantEngine.Core.Tests/FormulaServiceTests.cs b/src/dotnet/QuantEngine.Core.Tests/FormulaServiceTests.cs
new file mode 100644
index 00000000..63594305
--- /dev/null
+++ b/src/dotnet/QuantEngine.Core.Tests/FormulaServiceTests.cs
@@ -0,0 +1,48 @@
+using Moq;
+using QuantEngine.Application.Services;
+using QuantEngine.Core.Domain;
+using QuantEngine.Core.Interfaces;
+
+namespace QuantEngine.Core.Tests;
+
+public class FormulaServiceTests
+{
+    [Fact]
+    public async Task ComputeAndRecordFinalDecisionAsync_NormalizesInputs()
+    {
+        var historyStore = new Mock<IPostgresqlHistoryStore>(MockBehavior.Strict);
+        var learningStore = new Mock<INormalizedLearningStore>(MockBehavior.Strict);
+
+        learningStore.Setup(s => s.AppendDecisionAsync(It.IsAny<DecisionEventRecord>()))
+            .ReturnsAsync(Guid.NewGuid());
+
+        var service = new FormulaService(historyStore.Object, new DecisionLearningService(learningStore.Object));
+
+        var result = await service.ComputeAndRecordFinalDecisionAsync(
+            new Dictionary<string, object>
+            {
+                ["entryModeGate"] = "PASS",
+                ["entryMode"] = "PULLBACK",
+                ["leaderGate"] = "PASS",
+                ["acGate"] = "CLEAR",
+                ["priceStatus"] = "PRICE_OK",
+                ["atr20"] = 1.5
+            },
+            " decision-1 ",
+            " 005930 ",
+            " v1 ",
+            []);
+
+        Assert.NotEqual(Guid.Empty, result);
+        learningStore.VerifyAll();
+    }
+
+    [Fact]
+    public async Task AppendFormulaRunAsync_RejectsBlankName()
+    {
+        var service = new FormulaService(new Mock<IPostgresqlHistoryStore>().Object, new DecisionLearningService(new Mock<INormalizedLearningStore>().Object));
+
+        await Assert.ThrowsAsync<ArgumentException>(() =>
+            service.AppendFormulaRunAsync("  ", new Dictionary<string, object?>()));
+    }
+}