refactor: extract rescue_transcript helper from close and clean

cmd_close and cmd_clean each rescued <party dir>/log to
$HOME/party-<name>-<timestamp>.log before removing the dir, with
close's drain poll as the only difference. Share the mechanism in one
helper and keep each caller's own messages and control flow.

party

@@ -879,6 +879,40 @@ EOF
     echo "Party '$name' started. Attach from a fresh shell with: party join $name"
 }
 
+# Rescue <dir>/log to $HOME/party-<name>-<UTC timestamp>.log before the
+# per-party dir is removed. When drain=1 (cmd_close, right after
+# kill-server), the pipe-pane `cat` children may still be draining
+# their last bytes, so poll for two equal size samples (bounded,
+# integer sleeps only) before moving; cmd_clean's dead-server check
+# already confirmed nothing is still writing, so it passes drain=0. A
+# same-filesystem mv is a rename and would keep catching late writes
+# regardless, but $HOME and PARTY_SOCKET_DIR are commonly different
+# filesystems (tmpfs /tmp vs a home partition), where mv is copy+unlink
+# and tail bytes written after the copy started would be lost from the
+# copy.
+#
+# Sets _rt_dest to the destination path on a successful move, or to ''
+# when there was nothing to rescue. Returns 0 in both those cases; 2
+# when HOME is unset; 1 when mv failed.
+rescue_transcript() {
+    _rt_dir="$1" _rt_name="$2" _rt_drain="$3"
+    _rt_dest=''
+    [ -s "$_rt_dir/log" ] || return 0
+    [ -n "$HOME" ] || return 2
+    if [ "$_rt_drain" = 1 ]; then
+        _rt_prev=-1
+        for _rt_i in 1 2 3; do
+            _rt_size=$(wc -c < "$_rt_dir/log")
+            [ "$_rt_size" -eq "$_rt_prev" ] && break
+            _rt_prev="$_rt_size"
+            sleep 1
+        done
+    fi
+    _rt_dest="$HOME/party-$_rt_name-$(date -u '+%Y%m%d-%H%M%S').log"
+    mv "$_rt_dir/log" "$_rt_dest" 2>/dev/null || { _rt_dest=''; return 1; }
+    return 0
+}
+
 cmd_close() {
     name=
     while [ $# -gt 0 ]; do
@@ -955,38 +989,21 @@ cmd_close() {
 
     # Rescue a transcript before the dir vanishes: losing the night's
     # log to a routine close is exactly the accident class the threat
-    # model says to prevent. After kill-server the pipe-pane `cat`
+    # model says to prevent. A failed rescue (HOME unset, mv error)
-    # children are exiting but may still be draining their last bytes,
+    # leaves the party dir in place rather than deleting it out from
-    # so poll for two equal size samples (bounded, integer sleeps only)
+    # under a promise the message just made; kill-server already ran,
-    # before moving it. A same-filesystem mv is a rename and would keep
+    # so the party is dead either way, and `party close` (or `party
-    # catching late writes regardless, but $HOME and PARTY_SOCKET_DIR
+    # clean`) can be re-run once the transcript is off to safety.
-    # are commonly different filesystems (tmpfs /tmp vs a home
+    if rescue_transcript "$expected_dir" "$name" 1; then
-    # partition), where mv is copy+unlink and tail bytes written after
+        [ -z "$_rt_dest" ] || echo "party close: transcript saved to $_rt_dest"
-    # the copy started would be lost from the copy. A failed rescue
+    else
-    # (HOME unset, mv error) leaves the party dir in place rather than
+        _rt_rc=$?
-    # deleting it out from under a promise the message just made;
+        if [ "$_rt_rc" -eq 2 ]; then
-    # kill-server already ran, so the party is dead either way, and
-    # `party close` (or `party clean`) can be re-run once the transcript
-    # is off to safety.
-    if [ -s "$expected_dir/log" ]; then
-        if [ -z "$HOME" ]; then
             echo "party close: HOME is unset; transcript kept, party dir left in place ($expected_dir/log); re-run close after fixing." >&2
-            exit 1
-        fi
-        _cl_prev=-1
-        for _cl_i in 1 2 3; do
-            _cl_size=$(wc -c < "$expected_dir/log")
-            [ "$_cl_size" -eq "$_cl_prev" ] && break
-            _cl_prev="$_cl_size"
-            sleep 1
-        done
-        _cl_dest="$HOME/party-$name-$(date -u '+%Y%m%d-%H%M%S').log"
-        if mv "$expected_dir/log" "$_cl_dest" 2>/dev/null; then
-            echo "party close: transcript saved to $_cl_dest"
         else
             echo "party close: could not save transcript; party dir left in place ($expected_dir/log); re-run close after fixing." >&2
-            exit 1
         fi
+        exit 1
     fi
 
     rm -rf "$expected_dir"
@@ -1029,20 +1046,18 @@ EOF
         # already confirmed dead by the liveness check above, so unlike
         # close there's no pipe-pane `cat` still draining and no
         # quiescence poll is needed before moving it.
-        if [ -s "$d/log" ]; then
+        _cn_name=${d##*"party-$USER:"}
-            if [ -z "$HOME" ]; then
+        _cn_name=${_cn_name%.d}
+        if rescue_transcript "$d" "$_cn_name" 0; then
+            [ -z "$_rt_dest" ] || echo "party clean: transcript saved to $_rt_dest"
+        else
+            _rt_rc=$?
+            if [ "$_rt_rc" -eq 2 ]; then
                 echo "party clean: skipping $d (HOME is unset; leaving transcript)" >&2
-                continue
-            fi
-            _cn_name=${d##*"party-$USER:"}
-            _cn_name=${_cn_name%.d}
-            _cn_dest="$HOME/party-$_cn_name-$(date -u '+%Y%m%d-%H%M%S').log"
-            if mv "$d/log" "$_cn_dest" 2>/dev/null; then
-                echo "party clean: transcript saved to $_cn_dest"
             else
                 echo "party clean: skipping $d (could not save transcript)" >&2
-                continue
             fi
+            continue
         fi
 
         rm -rf "$d"