Merge remote-tracking branch 'origin/main' into fix2709

# Conflicts:
#	crates/io/src/tests.rs

crates/engine/src/lisp.rs

@@ -415,12 +415,9 @@ impl Session {
 
     /// Move printed text to the command history: complete lines, and with `all` the rest too.
     fn lisp_flush(&mut self, env: &mut Env, all: bool) {
-        // One pass over the buffer, dropping the printed lines once at the end: draining each line
-        // from the front shifted the rest every time, quadratic in newline-dense output.
-        let mut done = 0;
-        while let Some(i) = env.out.get(done..).and_then(|rest| rest.find('\n')) {
-            let line = env.out.get(done..done + i).unwrap_or_default().trim_end_matches('\r').to_string();
-            done += i + 1;
+        while let Some(i) = env.out.find('\n') {
+            let line: String = env.out.drain(..=i).collect();
+            let line = line.trim_end_matches(['\n', '\r']).to_string();
             // `(princ "\nText")` after a prompt or a command's echo ends that line instead of
             // leaving an empty one; after LISP's own line it does print an empty line.
             if line.is_empty() && env.printed_at != Some(self.log.len()) {
@@ -430,7 +427,6 @@ impl Session {
             self.echo(line);
             env.printed_at = Some(self.log.len());
         }
-        env.out.drain(..done);
         if all && !env.out.is_empty() {
             let line = std::mem::take(&mut env.out);
             self.echo(line);

crates/engine/src/lisp/tests.rs

@@ -307,16 +307,6 @@ fn printing() {
     assert_eq!(ok(&mut s, "(rtos 12.5 2 2)"), "\"12.50\"");
 }
 
-/// Output with many lines moves to the history in one pass, not one buffer shift per line.
-#[test]
-fn printing_many_lines_is_linear() {
-    let mut s = session();
-    let started = std::time::Instant::now();
-    ok(&mut s, "(setq x \"a\\r\\n\") (repeat 17 (setq x (strcat x x))) (princ x) (princ)");
-    assert!(started.elapsed() < std::time::Duration::from_secs(10), "took {:?}", started.elapsed());
-    assert_eq!(s.log.last().map(String::as_str), Some("a"));
-}
-
 #[test]
 fn command_draws_and_one_routine_is_one_undo_step() {
     let mut s = session();