fix deploy time issue

Author: joelhawksley

config/initializers/app_version.rb

@@ -1 +1,26 @@
-DEPLOY_TIME = Time.now.to_i
+# frozen_string_literal: true
+
+# Identifies the running release. It MUST be identical across every process of a
+# single deploy (web, worker, etc.) and change when new code ships — it's what
+# tells long-lived realtime display pages to reload after a deploy.
+#
+# It must NOT be derived from per-process boot time: the web and worker
+# processes boot at different seconds, so a `Time.now` value would differ
+# between the process that renders the display page and the worker process that
+# runs DeviceBroadcaster. Every cross-process refresh broadcast would then look
+# like a brand-new deploy and force a full-page reload (an e-ink flash) every
+# minute.
+#
+# Prefer an explicit/platform-provided release id; otherwise fall back to a
+# digest of the compiled assets (built once per deploy, identical across all
+# dynos), and finally to boot time for local single-process runs.
+DEPLOY_TIME =
+  ENV["DEPLOY_VERSION"].presence ||
+  ENV["HEROKU_RELEASE_VERSION"].presence ||
+  ENV["HEROKU_SLUG_COMMIT"].presence ||
+  begin
+    builds = Dir[Rails.root.join("app/assets/builds/*")].sort
+    builds.any? ? Digest::MD5.hexdigest(builds.map { |f| File.read(f) }.join) : Time.now.to_i
+  rescue
+    Time.now.to_i
+  end