diff --git a/c#/crawler/src/EntryPoint.cs b/c#/crawler/src/EntryPoint.cs
index 799a93ab..447c0a00 100644
--- a/c#/crawler/src/EntryPoint.cs
+++ b/c#/crawler/src/EntryPoint.cs
@@ -52,6 +52,7 @@ protected override void ConfigureContainer(HostBuilderContext context, Container
                 // eager initial all keyed CrawlerLocks singleton instances
                 // in order to sync their timer of WithLogTrace
                 .AutoActivate());
+        builder.RegisterType<ReplySignatureSaver>();
         builder.RegisterType<AuthorRevisionSaver>();
         builder.RegisterType<UserParser>();
         builder.RegisterType<ThreadLateCrawler>();
diff --git a/c#/crawler/src/Tieba/Crawl/Saver/Post/ReplySaver.cs b/c#/crawler/src/Tieba/Crawl/Saver/Post/ReplySaver.cs
index e418bfc0..12935dee 100644
--- a/c#/crawler/src/Tieba/Crawl/Saver/Post/ReplySaver.cs
+++ b/c#/crawler/src/Tieba/Crawl/Saver/Post/ReplySaver.cs
@@ -1,11 +1,11 @@
-using System.IO.Hashing;
 using PredicateBuilder = LinqKit.PredicateBuilder;
 
 namespace tbm.Crawler.Tieba.Crawl.Saver;
 
-public partial class ReplySaver(
+public class ReplySaver(
         ILogger<ReplySaver> logger,
         ConcurrentDictionary<PostId, ReplyPost> posts,
+        ReplySignatureSaver replySignatureSaver,
         AuthorRevisionSaver.New authorRevisionSaverFactory)
     : PostSaver<ReplyPost, BaseReplyRevision>(
         logger, posts, authorRevisionSaverFactory, PostType.Reply)
@@ -55,7 +55,7 @@ public override SaverChangeSet<ReplyPost> Save(CrawlerDbContext db)
             .Select(r => new ReplyContent {Pid = r.Pid, ProtoBufBytes = r.Content}));
         SaveReplyContentImages(db, changeSet.NewlyAdded);
         PostSaveHandlers += AuthorRevisionSaver.SaveAuthorExpGradeRevisions(db, changeSet.AllAfter).Invoke;
-        PostSaveHandlers += SaveReplySignatures(db, changeSet.AllAfter).Invoke;
+        PostSaveHandlers += replySignatureSaver.SaveReplySignatures(db, changeSet.AllAfter).Invoke;
 
         return changeSet;
     }
@@ -115,73 +115,3 @@ on existing.UrlFilename equals newInContent.UrlFilename
         }));
     }
 }
-public partial class ReplySaver
-{
-    private static readonly HashSet<UniqueSignature> GlobalLocks = [];
-    private readonly List<UniqueSignature> _localLocks = [];
-
-    private Action SaveReplySignatures(CrawlerDbContext db, IEnumerable<ReplyPost> replies)
-    {
-        SharedHelper.GetNowTimestamp(out var now);
-        var signatures = replies
-            .Where(r => r is {SignatureId: not null, Signature: not null})
-            .DistinctBy(r => r.SignatureId)
-            .Select(r => new ReplySignature
-            {
-                UserId = r.AuthorUid,
-                SignatureId = (uint)r.SignatureId!,
-                XxHash3 = XxHash3.Hash(r.Signature!),
-                ProtoBufBytes = r.Signature!,
-                FirstSeenAt = now,
-                LastSeenAt = now
-            }).ToList();
-        if (signatures.Count == 0) return () => { };
-
-        var uniqueSignatures = signatures
-            .ConvertAll(s => new UniqueSignature(s.SignatureId, s.XxHash3));
-        var existingSignatures = (
-            from s in db.ReplySignatures.AsTracking()
-            where uniqueSignatures.Select(us => us.Id).Contains(s.SignatureId)
-
-                  // server side eval doesn't need ByteArrayEqualityComparer
-                  && uniqueSignatures.Select(us => us.XxHash3).Contains(s.XxHash3)
-            select s
-        ).ToList();
-        (from existing in existingSignatures
-                join newInReply in signatures on existing.SignatureId equals newInReply.SignatureId
-                select (existing, newInReply))
-            .ForEach(t => t.existing.LastSeenAt = t.newInReply.LastSeenAt);
-
-        lock (GlobalLocks)
-        {
-            var newSignaturesExceptLocked = signatures
-                .ExceptBy(existingSignatures.Select(s => s.SignatureId), s => s.SignatureId)
-                .ExceptBy(GlobalLocks, s => new(s.SignatureId, s.XxHash3))
-                .ToList();
-            if (newSignaturesExceptLocked.Count == 0) return () => { };
-
-            _localLocks.AddRange(newSignaturesExceptLocked
-                .Select(s => new UniqueSignature(s.SignatureId, s.XxHash3)));
-            GlobalLocks.UnionWith(_localLocks);
-            db.ReplySignatures.AddRange(newSignaturesExceptLocked);
-        }
-        return () =>
-        {
-            lock (GlobalLocks) GlobalLocks.ExceptWith(_localLocks);
-        };
-    }
-
-    private sealed record UniqueSignature(uint Id, byte[] XxHash3)
-    {
-        public bool Equals(UniqueSignature? other) =>
-            other != null && Id == other.Id && new ByteArrayEqualityComparer().Equals(XxHash3, other.XxHash3);
-
-        public override int GetHashCode()
-        {
-            var hash = default(HashCode);
-            hash.Add(Id);
-            hash.AddBytes(XxHash3);
-            return hash.ToHashCode();
-        }
-    }
-}
diff --git a/c#/crawler/src/Tieba/Crawl/Saver/ReplySignatureSaver.cs b/c#/crawler/src/Tieba/Crawl/Saver/ReplySignatureSaver.cs
new file mode 100644
index 00000000..84aa718c
--- /dev/null
+++ b/c#/crawler/src/Tieba/Crawl/Saver/ReplySignatureSaver.cs
@@ -0,0 +1,74 @@
+using System.IO.Hashing;
+
+namespace tbm.Crawler.Tieba.Crawl.Saver;
+
+public class ReplySignatureSaver
+{
+    private static readonly HashSet<UniqueSignature> GlobalLocks = [];
+    private readonly List<UniqueSignature> _localLocks = [];
+
+    public Action SaveReplySignatures(CrawlerDbContext db, IEnumerable<ReplyPost> replies)
+    {
+        SharedHelper.GetNowTimestamp(out var now);
+        var signatures = replies
+            .Where(r => r is {SignatureId: not null, Signature: not null})
+            .DistinctBy(r => r.SignatureId)
+            .Select(r => new ReplySignature
+            {
+                UserId = r.AuthorUid,
+                SignatureId = (uint)r.SignatureId!,
+                XxHash3 = XxHash3.Hash(r.Signature!),
+                ProtoBufBytes = r.Signature!,
+                FirstSeenAt = now,
+                LastSeenAt = now
+            }).ToList();
+        if (signatures.Count == 0) return () => { };
+
+        var uniqueSignatures = signatures
+            .ConvertAll(s => new UniqueSignature(s.SignatureId, s.XxHash3));
+        var existingSignatures = (
+            from s in db.ReplySignatures.AsTracking()
+            where uniqueSignatures.Select(us => us.Id).Contains(s.SignatureId)
+
+                  // server side eval doesn't need ByteArrayEqualityComparer
+                  && uniqueSignatures.Select(us => us.XxHash3).Contains(s.XxHash3)
+            select s
+        ).ToList();
+        (from existing in existingSignatures
+                join newInReply in signatures on existing.SignatureId equals newInReply.SignatureId
+                select (existing, newInReply))
+            .ForEach(t => t.existing.LastSeenAt = t.newInReply.LastSeenAt);
+
+        lock (GlobalLocks)
+        {
+            var newSignaturesExceptLocked = signatures
+                .ExceptBy(existingSignatures.Select(s => s.SignatureId), s => s.SignatureId)
+                .ExceptBy(GlobalLocks, s => new(s.SignatureId, s.XxHash3))
+                .ToList();
+            if (newSignaturesExceptLocked.Count == 0) return () => { };
+
+            _localLocks.AddRange(newSignaturesExceptLocked
+                .Select(s => new UniqueSignature(s.SignatureId, s.XxHash3)));
+            GlobalLocks.UnionWith(_localLocks);
+            db.ReplySignatures.AddRange(newSignaturesExceptLocked);
+        }
+        return () =>
+        {
+            lock (GlobalLocks) GlobalLocks.ExceptWith(_localLocks);
+        };
+    }
+
+    private sealed record UniqueSignature(uint Id, byte[] XxHash3)
+    {
+        public bool Equals(UniqueSignature? other) =>
+            other != null && Id == other.Id && new ByteArrayEqualityComparer().Equals(XxHash3, other.XxHash3);
+
+        public override int GetHashCode()
+        {
+            var hash = default(HashCode);
+            hash.Add(Id);
+            hash.AddBytes(XxHash3);
+            return hash.ToHashCode();
+        }
+    }
+}