diff --git a/0051/SESSION-0051.0-TRANSCRIPT-2026-05-31T10-50--INPROGRESS.md b/0051/SESSION-0051.0-TRANSCRIPT-2026-05-31T10-50--INPROGRESS.md
new file mode 100644
index 0000000..62fb502
--- /dev/null
+++ b/0051/SESSION-0051.0-TRANSCRIPT-2026-05-31T10-50--INPROGRESS.md
@@ -0,0 +1,15 @@
+# Session 0051.0 — Transcript
+
+> Date: 2026-05-31
+> Start: 2026-05-31T10-50 (PST implied)
+> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
+>
+> This file reserves session ID 0051. The driver replaces this body
+> with the full transcript before publishing, and renames the file to
+> its final SESSION-0051.0-TRANSCRIPT-2026-05-31T10-50--<end>.md form.
+
+---
+
+## Launch prompt
+
+_(launch prompt not captured at claim time)_
diff --git a/sessions.json b/sessions.json
index 309568b..f799126 100644
--- a/sessions.json
+++ b/sessions.json
@@ -136,5 +136,8 @@
   },
   "0050": {
     "title": ""
+  },
+  "0051": {
+    "title": ""
   }
 }