diff --git a/db/migrate/20240910145644_add_pieces_jointes_seen_at_to_follows.rb b/db/migrate/20240910145644_add_pieces_jointes_seen_at_to_follows.rb
new file mode 100644
index 000000000..cce53f945
--- /dev/null
+++ b/db/migrate/20240910145644_add_pieces_jointes_seen_at_to_follows.rb
@@ -0,0 +1,12 @@
+# frozen_string_literal: true
+
+class AddPiecesJointesSeenAtToFollows < ActiveRecord::Migration[7.0]
+  def up
+    add_column :follows, :pieces_jointes_seen_at, :datetime
+    change_column_default :follows, :pieces_jointes_seen_at, from: nil, to: 'CURRENT_TIMESTAMP'
+  end
+
+  def down
+    remove_column :follows, :pieces_jointes_seen_at
+  end
+end
diff --git a/db/migrate/20240911064340_backfill_follows_with_pieces_jointes_seen_at.rb b/db/migrate/20240911064340_backfill_follows_with_pieces_jointes_seen_at.rb
new file mode 100644
index 000000000..82a51de34
--- /dev/null
+++ b/db/migrate/20240911064340_backfill_follows_with_pieces_jointes_seen_at.rb
@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class BackfillFollowsWithPiecesJointesSeenAt < ActiveRecord::Migration[7.0]
+  disable_ddl_transaction!
+  def up
+    Follow.in_batches do |relation|
+      relation.update_all pieces_jointes_seen_at: Time.zone.now
+      sleep(0.001) # throttle
+    end
+  end
+
+  def down
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index fd9774819..e55fcb86b 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -691,6 +691,7 @@ ActiveRecord::Schema[7.0].define(version: 2024_09_23_125619) do
     t.integer "dossier_id", null: false
     t.integer "instructeur_id", null: false
     t.datetime "messagerie_seen_at", precision: nil, null: false
+    t.datetime "pieces_jointes_seen_at"
     t.datetime "unfollowed_at", precision: nil
     t.datetime "updated_at", precision: nil
     t.index ["dossier_id"], name: "index_follows_on_dossier_id"