diff --git a/bin/rclaude b/bin/rclaude
index 5e94bf0..41991be 100755
--- a/bin/rclaude
+++ b/bin/rclaude
@@ -881,10 +881,13 @@ EOF
             /*) ;;
             *)  echo "rclaude send --slash: text must start with '/' (got: $_text)" >&2; exit 2 ;;
         esac
-        case $_text in
-            *"$(printf '\n')"*)
-                echo "rclaude send --slash: text must not contain newlines" >&2; exit 2 ;;
-        esac
+        # POSIX-portable newline check: command substitution strips trailing
+        # newlines, so a glob with $(printf '\n') won't work. Strip with tr
+        # and compare lengths instead.
+        _text_no_nl=$(printf '%s' "$_text" | tr -d '\n')
+        if [ "$_text_no_nl" != "$_text" ]; then
+            echo "rclaude send --slash: text must not contain newlines" >&2; exit 2
+        fi
     fi
 
     # Gather candidate rows across all hosts, then filter.
@@ -911,11 +914,18 @@ EOF
     # `while` runs in a subshell under POSIX sh and would lose mutations).
     _rowfile=$(mktemp /tmp/rclaude-send.XXXXXX 2>/dev/null || echo /tmp/rclaude-send.$$)
     printf '%s\n' "$_rows" > "$_rowfile"
+    # Every send pre-clears the target's input line. tmux send-keys -l types
+    # into whatever buffer is focused — if Claude is mid-turn or has queued
+    # input, the payload would otherwise concatenate with stray text. C-a
+    # moves to start of line, C-k kills to end. This is mandatory for
+    # --slash (slash commands fire only when they're the entire message)
+    # and harmless for prose (the buffer is normally empty between turns).
     while IFS=$(printf '\t') read -r _host _kind _sess _detail; do
         [ -z "$_sess" ] && continue
         _total=$((_total + 1))
         if is_local "$_host"; then
-            if tmux send-keys -t "$_sess" -l -- "$_text" 2>/dev/null \
+            if tmux send-keys -t "$_sess" C-a C-k 2>/dev/null \
+                && tmux send-keys -t "$_sess" -l -- "$_text" 2>/dev/null \
                 && tmux send-keys -t "$_sess" Enter 2>/dev/null; then
                 :
             else
@@ -925,7 +935,7 @@ EOF
         else
             _q_sess=$(sh_quote "$_sess")
             if ssh -o BatchMode=yes -o ConnectTimeout=3 "$_host" \
-                "tmux send-keys -t $_q_sess -l -- $_quoted_text && tmux send-keys -t $_q_sess Enter" \
+                "tmux send-keys -t $_q_sess C-a C-k && tmux send-keys -t $_q_sess -l -- $_quoted_text && tmux send-keys -t $_q_sess Enter" \
                 </dev/null >/dev/null 2>&1; then
                 :
             else