diff --git a/.mutant.yml b/.mutant.yml
index d1bdef2..936dd53 100644
--- a/.mutant.yml
+++ b/.mutant.yml
@@ -28,4 +28,5 @@ matcher:
     - En57::Benchmark::ConcurrentAppendConflictingTags*
     - En57::Benchmark::ConcurrentAppendNoFailIf*
     - En57::Benchmark::ConcurrentAppendNonConflictingTags*
+    - En57::Benchmark::ConcurrentAppendNonConflictingTagsSeeded*
     - En57::Benchmark::Scenario#concurrently # thread raise mutation survives despite direct coverage
diff --git a/database.toml b/database.toml
index 2102715..a91f5eb 100644
--- a/database.toml
+++ b/database.toml
@@ -8,6 +8,14 @@ path = "db/schema/0.1.0.sql"
 type = "sql-file"
 path = "db/schema/0.1.0.sql"
 
+[instances.concurrent-append-non-conflicting-tags-seeded.seeds.schema]
+type = "sql-file"
+path = "db/schema/0.1.0.sql"
+
+[instances.concurrent-append-non-conflicting-tags-seeded.seeds.events]
+type = "sql-file"
+path = "db/seeds/concurrent_append_non_conflicting_tags_seeded.sql"
+
 [instances.append-no-fail-if.seeds.schema]
 type = "sql-file"
 path = "db/schema/0.1.0.sql"
diff --git a/db/seeds/concurrent_append_non_conflicting_tags_seeded.sql b/db/seeds/concurrent_append_non_conflicting_tags_seeded.sql
new file mode 100644
index 0000000..da205ff
--- /dev/null
+++ b/db/seeds/concurrent_append_non_conflicting_tags_seeded.sql
@@ -0,0 +1,18 @@
+-- Seeds 1,000,000 events, each carrying a single random "writer:<8 hex>" tag.
+-- The tag shape mirrors ConcurrentAppendNonConflictingTagsSeeded's
+-- `writer:#{SecureRandom.hex(4)}`, so the tag index is populated with values
+-- of the same shape the benchmark queries.
+INSERT INTO en57.events (id, type)
+SELECT
+    gen_random_uuid (),
+    'event_benchmarked'
+FROM
+    generate_series(1, 1000000);
+
+INSERT INTO en57.tags (event_id, value)
+SELECT
+    id,
+    'writer:' || substr(md5(random()::text), 1, 8)
+FROM
+    en57.events;
+
diff --git a/lib/benchmark/concurrent_append_non_conflicting_tags_seeded.rb b/lib/benchmark/concurrent_append_non_conflicting_tags_seeded.rb
new file mode 100644
index 0000000..7aba247
--- /dev/null
+++ b/lib/benchmark/concurrent_append_non_conflicting_tags_seeded.rb
@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module En57
+  module Benchmark
+    class ConcurrentAppendNonConflictingTagsSeeded < Scenario
+      SEEDED_EVENTS = 1_000_000
+
+      def initialize(...)
+        super
+        @event_store =
+          EventStore.for_pooled_pg(@database_url, max_connections: @concurrency)
+      end
+
+      private
+
+      def call
+        type = "event_benchmarked"
+        barrier = Concurrent::CyclicBarrier.new(@concurrency)
+
+        concurrently(@concurrency) do
+          tags = %W[writer:#{SecureRandom.hex(4)}]
+          scope = @event_store.read.of_type(type).with_tag(tags)
+          events =
+            Array.new(@batch_size) { En57::Event.new(type: type, tags: tags) }
+
+          barrier.wait
+
+          @measure.call do
+            begin
+              @event_store.append(events, fail_if: scope.after(position = 0))
+            rescue AppendConditionViolated
+              record_retry
+              retry
+            end
+          end
+        end
+      end
+
+      def verify =
+        @event_store.read.each.to_a.size ==
+          SEEDED_EVENTS + total_runs * @concurrency * @batch_size
+    end
+  end
+end
diff --git a/lib/en57/benchmark.rb b/lib/en57/benchmark.rb
index f3ac982..b9ee27b 100644
--- a/lib/en57/benchmark.rb
+++ b/lib/en57/benchmark.rb
@@ -162,13 +162,7 @@ module En57
       def warmup = @warmup_runs.times { call }
 
       def concurrently(concurrency)
-        Array
-          .new(concurrency) do
-            Thread.new do
-              yield
-            end
-          end
-          .each(&:value)
+        Array.new(concurrency) { Thread.new { yield } }.each(&:value)
       end
     end
 
@@ -176,6 +170,7 @@ module En57
     require_relative "../benchmark/append_non_conflicting_tags"
     require_relative "../benchmark/concurrent_append_no_fail_if"
     require_relative "../benchmark/concurrent_append_non_conflicting_tags"
+    require_relative "../benchmark/concurrent_append_non_conflicting_tags_seeded"
     require_relative "../benchmark/concurrent_append_conflicting_tags"
 
     class Runner
@@ -246,6 +241,21 @@ module En57
               batch_size: 100,
             )
           end,
+          "concurrent-append-non-conflicting-tags-seeded" => ->(
+            database_url,
+            warmup_runs,
+            measure
+          ) do
+            ConcurrentAppendNonConflictingTagsSeeded.new(
+              name: "Concurrent append, non-conflicting tags (seeded)",
+              database_url:,
+              measure:,
+              warmup_runs:,
+              runs:,
+              concurrency: 10,
+              batch_size: 100,
+            )
+          end,
           "concurrent-append-conflicting-tags" => ->(
             database_url,
             warmup_runs,
diff --git a/test/test_benchmark.rb b/test/test_benchmark.rb
index 9a13042..f0c123b 100644
--- a/test/test_benchmark.rb
+++ b/test/test_benchmark.rb
@@ -340,6 +340,7 @@ module En57
             append-non-conflicting-tags
             concurrent-append-no-fail-if
             concurrent-append-non-conflicting-tags
+            concurrent-append-non-conflicting-tags-seeded
             concurrent-append-conflicting-tags
           ],
           Runner.names,
@@ -373,6 +374,13 @@ module En57
             50,
             10,
           ],
+          [
+            "concurrent-append-non-conflicting-tags-seeded",
+            ConcurrentAppendNonConflictingTagsSeeded,
+            "Concurrent append, non-conflicting tags (seeded)",
+            50,
+            10,
+          ],
           [
             "concurrent-append-conflicting-tags",
             ConcurrentAppendConflictingTags,