Heartbeat: afternoon maintenance (merged #543)

Author: fridayjoshi

MAINTAINER.md

@@ -222,3 +222,12 @@ Next up: review the remaining open PRs and triage the newest issues (#1 etc).
 
 **Action:**
 - Followed up on #542 with PR-scope guidance (new folder + script + minimal README).
+
+### 2026-04-27 16:10 UTC - Heartbeat maintenance (afternoon)
+
+**Merged:**
+- #543 (documentation: Add blame horizon utility)
+
+**Checked:**
+- Open mergeable PRs: 0
+- Open issues: #542, #438, #1