feature: Draft Data Entry

VigilCareRecordsAPI/Services/PlausibilityValidator.cs

@@ -0,0 +1,53 @@
+public static class PlausibilityValidator
+{
+    // Plausible ranges define the outer boundary of physically possible values.
+    // These are NOT clinical alert thresholds — they catch device malfunctions,
+    // transcription errors, and misread handwriting from paper charts.
+    // A heart rate of 300 is clinically extreme but not impossible during VT;
+    // 400 is physically impossible and indicates a data entry mistake.
+    private static readonly Dictionary<string, (decimal Min, decimal Max)> _ranges = new()
+    {
+        ["HEART_RATE"]       = (1,    300),  // beats per minute; ceiling allows extreme tachycardia (e.g. VT)
+        ["TEMP_C"]           = (15,   50),  // core body temperature in °C
+        ["POTASSIUM_MEQ_L"]  = (0.1m, 12),  // serum potassium mEq/L; catches decimal misplacement (5.2 vs 52)
+        ["SPO2"]             = (50,   100), // peripheral oxygen saturation %
+        ["RESP_RATE"]        = (1,    80),  // respirations per minute
+        ["WBC_K_UL"]         = (0.1m, 500), // white blood cell count ×10³/µL
+        ["GLUCOSE_MG_DL"]    = (10,   1000), // blood glucose mg/dL
+        ["LACTATE_MMOL_L"]   = (0.1m, 30),  // blood lactate mmol/L
+        ["BP_SYSTOLIC"]      = (40,   300), // systolic blood pressure mmHg
+        ["BP_DIASTOLIC"]     = (20,   200), // diastolic blood pressure mmHg
+    };
+
+    /// <summary>
+    /// Returns true if the value falls within the plausible range for the given code.
+    /// Unknown observation codes pass plausibility — the code is validated elsewhere.
+    /// </summary>
+    public static bool IsPlausible(string observationCode, decimal value, out string? reason)
+    {
+        if (!_ranges.TryGetValue(observationCode, out var range))
+        {
+            // Unknown codes pass plausibility — the observation code itself
+            // is validated at the business rule layer, not here.
+            reason = null;
+            return true;
+        }
+
+        if (value < range.Min || value > range.Max)
+        {
+            reason = $"Value {value} is outside the plausible range " +
+                     $"[{range.Min}–{range.Max}] for {observationCode}.";
+            return false;
+        }
+
+        reason = null;
+        return true;
+    }
+
+    /// <summary>
+    /// Returns all known observation codes and their plausible ranges.
+    /// Used by the frontend to display valid input boundaries.
+    /// </summary>
+    public static IReadOnlyDictionary<string, (decimal Min, decimal Max)> GetAllRanges() =>
+        _ranges;
+}