diff --git a/lib/mixer/metrics/buffer.ex b/lib/mixer/metrics/buffer.ex
index 23366e0..3078cff 100644
--- a/lib/mixer/metrics/buffer.ex
+++ b/lib/mixer/metrics/buffer.ex
@@ -128,14 +128,18 @@ defmodule Mixer.Metrics.Buffer do
 
   defp do_flush(events) do
     rows = Enum.reverse(events)
+    count = length(rows)
 
     try do
-      {count, _} = Mixer.ClickhouseRepo.insert_all(PostEvent, rows)
+      # ClickHouse async inserts acknowledge writes immediately and always
+      # return num_rows: 0 — the data is queued for background commitment.
+      # We use our own row count for the log so it is always accurate.
+      Mixer.ClickhouseRepo.insert_all(PostEvent, rows)
       Logger.debug("[Mixer.Metrics.Buffer] Flushed #{count} event(s) to ClickHouse")
     rescue
       error ->
         Logger.error(
-          "[Mixer.Metrics.Buffer] Failed to flush #{length(rows)} event(s) to ClickHouse: " <>
+          "[Mixer.Metrics.Buffer] Failed to flush #{count} event(s) to ClickHouse: " <>
             Exception.message(error)
         )
     end
diff --git a/lib/mixer/metrics/post_event.ex b/lib/mixer/metrics/post_event.ex
index 191d6d0..71cb189 100644
--- a/lib/mixer/metrics/post_event.ex
+++ b/lib/mixer/metrics/post_event.ex
@@ -22,19 +22,23 @@ defmodule Mixer.Metrics.PostEvent do
   @primary_key false
 
   schema "post_events" do
-    # LowCardinality(String) in ClickHouse — keep values in the set above
-    field :event_type, :string
+    # Must be Ch-typed so ecto_ch emits LowCardinality(String) in the RowBinary
+    # header, matching the ClickHouse table DDL exactly.
+    field :event_type, Ch, type: "LowCardinality(String)"
 
     # The tweet that the event relates to
     field :tweet_id, Ecto.UUID
 
-    # The acting user; may be nil for anonymous views
-    field :user_id, Ecto.UUID
+    # The acting user; may be nil for anonymous views.
+    # Must be Ch-typed so ecto_ch emits Nullable(UUID) in the RowBinary header,
+    # matching the ClickHouse table DDL exactly.
+    field :user_id, Ch, type: "Nullable(UUID)"
 
     # Wall-clock time of the event (UTC, second precision)
     field :occurred_at, :utc_datetime
 
-    # Optional originating IP, useful for deduplicating anonymous views
-    field :ip_address, :string
+    # Optional originating IP, useful for deduplicating anonymous views.
+    # Nullable(String) for the same reason as user_id above.
+    field :ip_address, Ch, type: "Nullable(String)"
   end
 end
diff --git a/lib/mixer/posts/tweet.ex b/lib/mixer/posts/tweet.ex
index 3b0f984..5bd840e 100644
--- a/lib/mixer/posts/tweet.ex
+++ b/lib/mixer/posts/tweet.ex
@@ -66,6 +66,26 @@ defmodule Mixer.Posts.Tweet do
             end)
         end
       end
+
+      # Track a "comment" metric event whenever a reply is posted. We record
+      # the event against the *parent* tweet so that `get_summary/1` and
+      # `get_bulk_summaries/1` can count how many comments each tweet received.
+      change fn changeset, context ->
+        case Ash.Changeset.get_attribute(changeset, :parent_tweet_id) do
+          nil ->
+            changeset
+
+          parent_tweet_id ->
+            Ash.Changeset.after_action(changeset, fn _changeset, tweet ->
+              Mixer.Metrics.track_comment(
+                parent_tweet_id,
+                user_id: context.actor && context.actor.id
+              )
+
+              {:ok, tweet}
+            end)
+        end
+      end
     end
 
     update :update do
@@ -80,6 +100,7 @@ defmodule Mixer.Posts.Tweet do
         Ash.Changeset.after_action(changeset, fn _changeset, tweet ->
           case ensure_like(tweet, context.actor) do
             {:created, _like} ->
+              Mixer.Metrics.track_like(tweet.id, user_id: context.actor && context.actor.id)
               increment_likes(tweet, context.actor)
 
             {:noop, _like} ->
@@ -100,6 +121,7 @@ defmodule Mixer.Posts.Tweet do
         Ash.Changeset.after_action(changeset, fn _changeset, tweet ->
           case remove_like(tweet, context.actor) do
             {:deleted, _like} ->
+              Mixer.Metrics.track_unlike(tweet.id, user_id: context.actor && context.actor.id)
               decrement_likes(tweet, context.actor)
 
             {:noop, _like} ->
diff --git a/lib/mixer_web/controllers/page_controller.ex b/lib/mixer_web/controllers/page_controller.ex
index ac6467e..f2349f0 100644
--- a/lib/mixer_web/controllers/page_controller.ex
+++ b/lib/mixer_web/controllers/page_controller.ex
@@ -16,6 +16,8 @@ defmodule MixerWeb.PageController do
   end
 
   def show(conn, %{"tweet_id" => tweet_id}) do
+    user_id = conn.assigns[:current_user] && conn.assigns[:current_user].id
+    Mixer.Metrics.track_view(tweet_id, user_id: user_id, ip_address: conn.remote_ip)
     render_spa(conn, %{page: "tweet", tweet_id: tweet_id, user_id: nil})
   end