diff --git a/src/ScadaLink.Transport/Serialization/ManifestBuilder.cs b/src/ScadaLink.Transport/Serialization/ManifestBuilder.cs
new file mode 100644
index 0000000..de60b0c
--- /dev/null
+++ b/src/ScadaLink.Transport/Serialization/ManifestBuilder.cs
@@ -0,0 +1,47 @@
+using System.Security.Cryptography;
+using ScadaLink.Commons.Types.Transport;
+
+namespace ScadaLink.Transport.Serialization;
+
+/// <summary>
+/// Builds a <see cref="BundleManifest"/> for a freshly serialized bundle.
+/// Stamps the current format/schema version, captures the SHA-256 hash of the
+/// raw (post-encryption) content bytes, and copies through the supplied summary
+/// and content entries verbatim.
+/// </summary>
+public sealed class ManifestBuilder
+{
+    public const int CurrentBundleFormatVersion = 1;
+    public const string CurrentSchemaVersion = "1.0";
+
+    public BundleManifest Build(
+        string sourceEnvironment,
+        string exportedBy,
+        string scadaLinkVersion,
+        EncryptionMetadata? encryption,
+        BundleSummary summary,
+        IReadOnlyList<ManifestContentEntry> contents,
+        byte[] contentBytes)
+    {
+        ArgumentNullException.ThrowIfNull(sourceEnvironment);
+        ArgumentNullException.ThrowIfNull(exportedBy);
+        ArgumentNullException.ThrowIfNull(scadaLinkVersion);
+        ArgumentNullException.ThrowIfNull(summary);
+        ArgumentNullException.ThrowIfNull(contents);
+        ArgumentNullException.ThrowIfNull(contentBytes);
+
+        var contentHash = "sha256:" + Convert.ToHexString(SHA256.HashData(contentBytes)).ToLowerInvariant();
+
+        return new BundleManifest(
+            BundleFormatVersion: CurrentBundleFormatVersion,
+            SchemaVersion: CurrentSchemaVersion,
+            CreatedAtUtc: DateTimeOffset.UtcNow,
+            SourceEnvironment: sourceEnvironment,
+            ExportedBy: exportedBy,
+            ScadaLinkVersion: scadaLinkVersion,
+            ContentHash: contentHash,
+            Encryption: encryption,
+            Summary: summary,
+            Contents: contents);
+    }
+}
diff --git a/src/ScadaLink.Transport/Serialization/ManifestValidator.cs b/src/ScadaLink.Transport/Serialization/ManifestValidator.cs
new file mode 100644
index 0000000..4273dde
--- /dev/null
+++ b/src/ScadaLink.Transport/Serialization/ManifestValidator.cs
@@ -0,0 +1,50 @@
+using System.Security.Cryptography;
+using ScadaLink.Commons.Types.Transport;
+
+namespace ScadaLink.Transport.Serialization;
+
+/// <summary>
+/// Outcome of validating a <see cref="BundleManifest"/> against the supplied
+/// raw content bytes. Distinct values let the importer surface a precise
+/// rejection reason to the operator.
+/// </summary>
+public enum ManifestValidationResult
+{
+    Ok,
+    UnsupportedFormatVersion,
+    ContentHashMismatch,
+    MalformedManifest
+}
+
+/// <summary>
+/// Inspects a deserialized manifest plus the raw content bytes recovered from
+/// the bundle ZIP and reports the first integrity failure (or <see cref="ManifestValidationResult.Ok"/>).
+/// </summary>
+public sealed class ManifestValidator
+{
+    public ManifestValidationResult Validate(BundleManifest manifest, byte[] contentBytes)
+    {
+        if (manifest is null || contentBytes is null)
+        {
+            return ManifestValidationResult.MalformedManifest;
+        }
+
+        if (string.IsNullOrEmpty(manifest.SourceEnvironment) || manifest.Contents is null)
+        {
+            return ManifestValidationResult.MalformedManifest;
+        }
+
+        if (manifest.BundleFormatVersion != ManifestBuilder.CurrentBundleFormatVersion)
+        {
+            return ManifestValidationResult.UnsupportedFormatVersion;
+        }
+
+        var expected = "sha256:" + Convert.ToHexString(SHA256.HashData(contentBytes)).ToLowerInvariant();
+        if (!string.Equals(expected, manifest.ContentHash, StringComparison.Ordinal))
+        {
+            return ManifestValidationResult.ContentHashMismatch;
+        }
+
+        return ManifestValidationResult.Ok;
+    }
+}
diff --git a/tests/ScadaLink.Transport.Tests/Serialization/ManifestBuilderTests.cs b/tests/ScadaLink.Transport.Tests/Serialization/ManifestBuilderTests.cs
new file mode 100644
index 0000000..46a6e55
--- /dev/null
+++ b/tests/ScadaLink.Transport.Tests/Serialization/ManifestBuilderTests.cs
@@ -0,0 +1,103 @@
+using System.Security.Cryptography;
+using System.Text;
+using ScadaLink.Commons.Types.Transport;
+using ScadaLink.Transport.Serialization;
+
+namespace ScadaLink.Transport.Tests.Serialization;
+
+public sealed class ManifestBuilderTests
+{
+    private static BundleSummary EmptySummary => new(0, 0, 0, 0, 0, 0, 0, 0, 0);
+    private static IReadOnlyList<ManifestContentEntry> NoContents => Array.Empty<ManifestContentEntry>();
+
+    [Fact]
+    public void Build_populates_summary_from_contents()
+    {
+        var sut = new ManifestBuilder();
+        var summary = new BundleSummary(2, 1, 0, 0, 0, 0, 0, 0, 0);
+        var contents = new[]
+        {
+            new ManifestContentEntry("Template", "T1", 1, Array.Empty<string>()),
+            new ManifestContentEntry("Template", "T2", 1, new[] { "T1" }),
+            new ManifestContentEntry("TemplateFolder", "F1", 1, Array.Empty<string>()),
+        };
+
+        var manifest = sut.Build("env", "user", "1.0.0", encryption: null, summary, contents, contentBytes: new byte[] { 1, 2, 3 });
+
+        Assert.Equal(summary, manifest.Summary);
+        Assert.Equal(contents, manifest.Contents);
+        Assert.Equal("env", manifest.SourceEnvironment);
+        Assert.Equal("user", manifest.ExportedBy);
+        Assert.Equal("1.0.0", manifest.ScadaLinkVersion);
+        Assert.Equal(1, manifest.BundleFormatVersion);
+        Assert.Equal("1.0", manifest.SchemaVersion);
+        Assert.Null(manifest.Encryption);
+    }
+
+    [Fact]
+    public void Build_computes_content_hash_with_sha256_prefix()
+    {
+        var sut = new ManifestBuilder();
+        var bytes = Encoding.UTF8.GetBytes("known-content");
+        var expectedHashHex = Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
+
+        var manifest = sut.Build("env", "user", "v", encryption: null, EmptySummary, NoContents, bytes);
+
+        Assert.Equal("sha256:" + expectedHashHex, manifest.ContentHash);
+    }
+
+    [Fact]
+    public void Validate_rejects_unsupported_bundleFormatVersion()
+    {
+        var bytes = new byte[] { 1, 2, 3 };
+        var hash = "sha256:" + Convert.ToHexString(SHA256.HashData(bytes)).ToLowerInvariant();
+        var manifest = new BundleManifest(
+            BundleFormatVersion: 999,
+            SchemaVersion: "1.0",
+            CreatedAtUtc: DateTimeOffset.UtcNow,
+            SourceEnvironment: "env",
+            ExportedBy: "u",
+            ScadaLinkVersion: "v",
+            ContentHash: hash,
+            Encryption: null,
+            Summary: EmptySummary,
+            Contents: NoContents);
+
+        var result = new ManifestValidator().Validate(manifest, bytes);
+
+        Assert.Equal(ManifestValidationResult.UnsupportedFormatVersion, result);
+    }
+
+    [Fact]
+    public void Validate_rejects_when_contentHash_mismatch()
+    {
+        var bytes = new byte[] { 1, 2, 3 };
+        var manifest = new BundleManifest(
+            BundleFormatVersion: 1,
+            SchemaVersion: "1.0",
+            CreatedAtUtc: DateTimeOffset.UtcNow,
+            SourceEnvironment: "env",
+            ExportedBy: "u",
+            ScadaLinkVersion: "v",
+            ContentHash: "sha256:deadbeef",
+            Encryption: null,
+            Summary: EmptySummary,
+            Contents: NoContents);
+
+        var result = new ManifestValidator().Validate(manifest, bytes);
+
+        Assert.Equal(ManifestValidationResult.ContentHashMismatch, result);
+    }
+
+    [Fact]
+    public void Validate_accepts_well_formed_v1_manifest()
+    {
+        var sut = new ManifestBuilder();
+        var bytes = Encoding.UTF8.GetBytes("hello");
+        var manifest = sut.Build("env", "u", "v", encryption: null, EmptySummary, NoContents, bytes);
+
+        var result = new ManifestValidator().Validate(manifest, bytes);
+
+        Assert.Equal(ManifestValidationResult.Ok, result);
+    }
+}