diff --git a/src/messages/MessageSimilarity.cpp b/src/messages/MessageSimilarity.cpp
index 3019aea67..2f8157d6b 100644
--- a/src/messages/MessageSimilarity.cpp
+++ b/src/messages/MessageSimilarity.cpp
@@ -1,9 +1,17 @@
 #include "messages/MessageSimilarity.hpp"
 
+#include "Application.hpp"
+#include "controllers/accounts/AccountController.hpp"
+#include "messages/LimitedQueueSnapshot.hpp"  // IWYU pragma: keep
+#include "providers/twitch/TwitchAccount.hpp"
+#include "singletons/Settings.hpp"
+
 #include <algorithm>
 #include <vector>
 
-namespace chatterino::similarity::detail {
+namespace {
+
+using namespace chatterino;
 
 float relativeSimilarity(QStringView str1, QStringView str2)
 {
@@ -48,4 +56,66 @@ float relativeSimilarity(QStringView str1, QStringView str2)
     return float(z) / float(div);
 }
 
-}  // namespace chatterino::similarity::detail
+template <std::ranges::bidirectional_range T>
+float inMessages(const MessagePtr &msg, const T &messages)
+{
+    float similarityPercent = 0.0F;
+
+    for (const auto &prevMsg :
+         messages | std::views::reverse |
+             std::views::take(getSettings()->hideSimilarMaxMessagesToCheck))
+    {
+        if (prevMsg->parseTime.secsTo(QTime::currentTime()) >=
+            getSettings()->hideSimilarMaxDelay)
+        {
+            break;
+        }
+        if (getSettings()->hideSimilarBySameUser &&
+            msg->loginName != prevMsg->loginName)
+        {
+            continue;
+        }
+        similarityPercent = std::max(
+            similarityPercent,
+            relativeSimilarity(msg->messageText, prevMsg->messageText));
+    }
+
+    return similarityPercent;
+}
+
+}  // namespace
+
+namespace chatterino {
+
+template <std::ranges::bidirectional_range T>
+void setSimilarityFlags(const MessagePtr &message, const T &messages)
+{
+    if (getSettings()->similarityEnabled)
+    {
+        bool isMyself =
+            message->loginName ==
+            getApp()->getAccounts()->twitch.getCurrent()->getUserName();
+        bool hideMyself = getSettings()->hideSimilarMyself;
+
+        if (isMyself && !hideMyself)
+        {
+            return;
+        }
+
+        if (inMessages(message, messages) > getSettings()->similarityPercentage)
+        {
+            message->flags.set(MessageFlag::Similar);
+            if (getSettings()->colorSimilarDisabled)
+            {
+                message->flags.set(MessageFlag::Disabled);
+            }
+        }
+    }
+}
+
+template void setSimilarityFlags<std::vector<MessagePtr>>(
+    const MessagePtr &msg, const std::vector<MessagePtr> &messages);
+template void setSimilarityFlags<LimitedQueueSnapshot<MessagePtr>>(
+    const MessagePtr &msg, const LimitedQueueSnapshot<MessagePtr> &messages);
+
+}  // namespace chatterino
diff --git a/src/messages/MessageSimilarity.hpp b/src/messages/MessageSimilarity.hpp
index 562e574ad..54d0214d7 100644
--- a/src/messages/MessageSimilarity.hpp
+++ b/src/messages/MessageSimilarity.hpp
@@ -1,73 +1,11 @@
 #pragma once
 
-#include "Application.hpp"
-#include "controllers/accounts/AccountController.hpp"
 #include "messages/Message.hpp"
-#include "providers/twitch/TwitchAccount.hpp"
-#include "singletons/Settings.hpp"
 
 #include <ranges>
-
-namespace chatterino::similarity::detail {
-
-float relativeSimilarity(QStringView str1, QStringView str2);
-
-float inMessages(const MessagePtr &msg,
-                 const std::ranges::bidirectional_range auto &messages)
-{
-    float similarityPercent = 0.0F;
-
-    for (const auto &prevMsg :
-         messages | std::views::reverse |
-             std::views::take(getSettings()->hideSimilarMaxMessagesToCheck))
-    {
-        if (prevMsg->parseTime.secsTo(QTime::currentTime()) >=
-            getSettings()->hideSimilarMaxDelay)
-        {
-            break;
-        }
-        if (getSettings()->hideSimilarBySameUser &&
-            msg->loginName != prevMsg->loginName)
-        {
-            continue;
-        }
-        similarityPercent = std::max(
-            similarityPercent,
-            relativeSimilarity(msg->messageText, prevMsg->messageText));
-    }
-
-    return similarityPercent;
-}
-
-}  // namespace chatterino::similarity::detail
-
 namespace chatterino {
 
-void setSimilarityFlags(const MessagePtr &message,
-                        const std::ranges::bidirectional_range auto &messages)
-{
-    if (getSettings()->similarityEnabled)
-    {
-        bool isMyself =
-            message->loginName ==
-            getApp()->getAccounts()->twitch.getCurrent()->getUserName();
-        bool hideMyself = getSettings()->hideSimilarMyself;
-
-        if (isMyself && !hideMyself)
-        {
-            return;
-        }
-
-        if (similarity::detail::inMessages(message, messages) >
-            getSettings()->similarityPercentage)
-        {
-            message->flags.set(MessageFlag::Similar);
-            if (getSettings()->colorSimilarDisabled)
-            {
-                message->flags.set(MessageFlag::Disabled);
-            }
-        }
-    }
-}
+template <std::ranges::bidirectional_range T>
+void setSimilarityFlags(const MessagePtr &message, const T &messages);
 
 }  // namespace chatterino
diff --git a/src/messages/MessageSink.hpp b/src/messages/MessageSink.hpp
index 07e7101a5..b44690ead 100644
--- a/src/messages/MessageSink.hpp
+++ b/src/messages/MessageSink.hpp
@@ -1,6 +1,7 @@
 #pragma once
 
 #include "common/enums/MessageContext.hpp"
+#include "common/FlagsEnum.hpp"
 #include "messages/MessageFlag.hpp"
 
 #include <memory>
@@ -15,7 +16,14 @@ using MessagePtr = std::shared_ptr<const Message>;
 
 enum class MessageSinkTrait : uint8_t {
     None = 0,
+
+    /// Messages with the `Highlighted` and `ShowInMentions` flags should be
+    /// added to the global mentions channel when encountered.
     AddMentionsToGlobalChannel = 1 << 0,
+
+    /// A channel-point redemption whose reward is not yet known should not be
+    /// added to this sink, but queued in the corresponding TwitchChannel
+    /// (`addQueuedRedemption`).
     RequiresKnownChannelPointReward = 1 << 1,
 };
 using MessageSinkTraits = FlagsEnum<MessageSinkTrait>;
@@ -51,7 +59,7 @@ public:
     /// If there is no message found, an empty shared-pointer is returned.
     virtual MessagePtr findMessageByID(QStringView id) = 0;
 
-    ///
+    /// Behaviour to be exercised when parsing/building messages for this sink.
     virtual MessageSinkTraits sinkTraits() const = 0;
 };
 
diff --git a/src/providers/twitch/TwitchChannel.cpp b/src/providers/twitch/TwitchChannel.cpp
index 86d26c249..00bd8c117 100644
--- a/src/providers/twitch/TwitchChannel.cpp
+++ b/src/providers/twitch/TwitchChannel.cpp
@@ -1356,8 +1356,6 @@ void TwitchChannel::loadRecentMessages()
                 {
                     msgs.push_back(msg);
                 }
-
-                tc->addRecentChatter(msg->displayName);
             }
 
             getApp()->getTwitch()->getMentionsChannel()->fillInMissingMessages(