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src/StellaOps.Zastava.Observer/Worker/BackoffCalculator.cs

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+using StellaOps.Zastava.Observer.Configuration;
+
+namespace StellaOps.Zastava.Observer.Worker;
+
+internal static class BackoffCalculator
+{
+    public static TimeSpan ComputeDelay(ObserverBackoffOptions options, int attempt, Random random)
+    {
+        ArgumentNullException.ThrowIfNull(options);
+        ArgumentNullException.ThrowIfNull(random);
+
+        var cappedAttempt = Math.Max(1, attempt);
+        var baseDelayMs = options.Initial.TotalMilliseconds * Math.Pow(2, cappedAttempt - 1);
+        baseDelayMs = Math.Min(baseDelayMs, options.Max.TotalMilliseconds);
+
+        if (options.JitterRatio <= 0)
+        {
+            return TimeSpan.FromMilliseconds(baseDelayMs);
+        }
+
+        var jitterWindow = baseDelayMs * options.JitterRatio;
+        var jitter = (random.NextDouble() * 2 - 1) * jitterWindow;
+        var jittered = Math.Clamp(baseDelayMs + jitter, options.Initial.TotalMilliseconds, options.Max.TotalMilliseconds);
+        return TimeSpan.FromMilliseconds(jittered);
+    }
+}