diff --git a/doc/IDEAS.md b/doc/IDEAS.md
index 4b459f5..4cf1d0a 100644
--- a/doc/IDEAS.md
+++ b/doc/IDEAS.md
@@ -84,10 +84,10 @@ echo "name=tester    agent=tester    cwd=$cwd" > s/new
 # Send a prompt to a session and return only the new output.
 send() {
     sid=$1; shift
-    offset=$(wc -c < s/$sid/chat)
     printf '%s' "$*" > s/$sid/prompt
     while [ "$(cat s/$sid/state)" = "idle" ]; do sleep 0.2; done
     while [ "$(cat s/$sid/state)" != "idle" ]; do sleep 1; done
+    offset=$(cat s/$sid/offset)
     tail -c +$((offset + 1)) s/$sid/chat
 }
 
diff --git a/doc/help.md b/doc/help.md
index 0dc407f..c6b4263 100644
--- a/doc/help.md
+++ b/doc/help.md
@@ -40,6 +40,7 @@ ollie/
       agent       active agent (r/w)
       backend     active backend (r/w)
       chat        conversation log (ro)
+      offset      byte offset of chat EOF before last prompt submit (ro)
       ctl         control (w)                stop, kill, clear, compact, rn <name>
       ctxsz       context size (ro)
       cwd         working directory (r/w)