daemon: add test-send subcommand, flatten newlines in send_prompt

test-send calls send_prompt() directly for debugging tmux delivery.
Flatten newlines to spaces in literal mode to prevent premature
input submission.

Co-Authored-By: ProofOfConcept <poc@bcachefs.org>

src/bin/poc-daemon/main.rs

@@ -116,6 +116,11 @@ enum Command {
         /// Value to set (omit to query)
         value: Option<f64>,
     },
+    /// Send a test message to the Claude pane
+    TestSend {
+        /// Message to send
+        message: Vec<String>,
+    },
     /// Dump full internal state as JSON
     Debug,
     /// Shut down daemon
@@ -256,6 +261,17 @@ async fn client_main(cmd: Command) -> Result<(), Box<dyn std::error::Error>> {
                     req.get().set_seconds(seconds.unwrap_or(300));
                     req.send().promise.await?;
                 }
+                Command::TestSend { message } => {
+                    let msg = message.join(" ");
+                    let pane = {
+                        let reply = daemon.status_request().send().promise.await?;
+                        let s = reply.get()?.get_status()?;
+                        s.get_claude_pane()?.to_str()?.to_string()
+                    };
+                    let ok = crate::tmux::send_prompt(&pane, &msg);
+                    println!("send_prompt(pane={}, ok={}): {}", pane, ok, msg);
+                    return Ok(());
+                }
                 Command::Afk => {
                     daemon.afk_request().send().promise.await?;
                     println!("marked AFK");

src/bin/poc-daemon/tmux.rs

@@ -35,9 +35,10 @@ pub fn send_prompt(pane: &str, msg: &str) -> bool {
     let preview: String = msg.chars().take(100).collect();
     info!("SEND [{pane}]: {preview}...");
 
-    // Type the message literally
+    // Type the message literally (flatten newlines — they'd submit the input early)
+    let flat: String = msg.chars().map(|c| if c == '\n' { ' ' } else { c }).collect();
     let ok = Command::new("tmux")
-        .args(["send-keys", "-t", pane, "-l", msg])
+        .args(["send-keys", "-t", pane, "-l", &flat])
         .output()
         .is_ok();
     if !ok {