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src/Scanner/__Libraries/StellaOps.Scanner.Analyzers.Lang.Bun/Internal/BunEvidenceHasher.cs

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+using System.Security.Cryptography;
+
+namespace StellaOps.Scanner.Analyzers.Lang.Bun.Internal;
+
+internal static class BunEvidenceHasher
+{
+    internal const int MaxPackageJsonEvidenceBytes = 1024 * 1024; // 1 MiB
+    internal const int MaxLockfileEvidenceBytes = 50 * 1024 * 1024; // 50 MiB (matches BunLockParser cap)
+
+    internal static string? TryComputeBoundedSha256(string path, int maxBytes, out string? skipReason)
+    {
+        skipReason = null;
+
+        try
+        {
+            var info = new FileInfo(path);
+            if (!info.Exists)
+            {
+                skipReason = "missing";
+                return null;
+            }
+
+            if (info.Length > maxBytes)
+            {
+                skipReason = $"size>{maxBytes}";
+                return null;
+            }
+
+            using var stream = File.OpenRead(path);
+            var hash = SHA256.HashData(stream);
+            return Convert.ToHexString(hash).ToLowerInvariant();
+        }
+        catch (UnauthorizedAccessException)
+        {
+            skipReason = "unauthorized";
+            return null;
+        }
+        catch (IOException)
+        {
+            skipReason = "io";
+            return null;
+        }
+    }
+}
+