diff --git a/sessions/0012/SESSION-0012.0-TRANSCRIPT-2026-06-10T21-53--INPROGRESS.md b/sessions/0012/SESSION-0012.0-TRANSCRIPT-2026-06-10T21-53--INPROGRESS.md
new file mode 100644
index 0000000..6195037
--- /dev/null
+++ b/sessions/0012/SESSION-0012.0-TRANSCRIPT-2026-06-10T21-53--INPROGRESS.md
@@ -0,0 +1,23 @@
+# Session 0012.0 — Transcript
+
+> App: vscode-cowriting-plugin
+> Start: 2026-06-10T21-53 (PST)
+> Type: planning-and-executing
+> Status: **PLACEHOLDER — claimed at session start; finalized at session end.**
+>
+> This file reserves session ID 0012 for vscode-cowriting-plugin. The driver replaces this
+> body with the full transcript and renames the file to its final
+> SESSION-0012.0-TRANSCRIPT-2026-06-10T21-53--<end>.md form at session end.
+
+## Launch prompt
+
+```
+Implement Feature #12 (F4 propose/accept) per the graduated spec vscode-cowriting-plugin-content/specs/coauthoring-propose-accept.md — plan just-in-time from its §7.2 slices, then execute; done = unit + host E2E green and the live smoke shows propose → accept → Claude-attributed. (Leg 3 of /goal F4: session 0010 captured #12, session 0011 graduated its spec.)
+
+```
+
+## Deferred decisions
+
+_Autonomous-mode low-confidence calls the driver made and would have
+liked operator input on. Appended as the session runs; surfaced at
+finalize. Empty if none._
diff --git a/sessions/sessions.json b/sessions/sessions.json
index 717318e..575794d 100644
--- a/sessions/sessions.json
+++ b/sessions/sessions.json
@@ -31,5 +31,8 @@
   },
   "0011": {
     "title": ""
+  },
+  "0012": {
+    "title": ""
   }
 }