fix(session): OSC 52 reads get a reply again (engine gate dropped them)

CHANGELOG.md

@@ -6,6 +6,16 @@ follow [Semantic Versioning](https://semver.org).
 
 ## [Unreleased]
 
+### Fixed
+
+- OSC 52 clipboard reads now work as documented. Since 0.5.0, a program
+  asking for the clipboard's contents got no reply at all: the request was
+  dropped before Ember's own setting was consulted, so `osc52_read = true`
+  had no effect, and with it off a program waiting for an answer could hang.
+  Ember now answers every read: with the clipboard's contents when
+  `osc52_read = true`, and with an empty reply otherwise (still the default),
+  so nothing is shared unless you opt in.
+
 ## [0.6.1] - 2026-09-25
 
 ### Fixed

crates/ember-session/src/local_pty.rs

@@ -522,6 +522,29 @@ mod tests {
         );
     }
 
+    /// The same promise, through the real path: the read's escape bytes go into
+    /// the engine, not a synthetic event into the listener. The engine has its
+    /// own OSC 52 gate ahead of the listener, and its default drops reads, which
+    /// left the pane silent while the listener-only test above kept passing.
+    #[test]
+    fn osc52_read_through_the_engine_replies_empty() {
+        let (tx, _rx) = mpsc::channel();
+        let outbox = Arc::new(Mutex::new(Vec::new()));
+        let listener = EmberListener {
+            events: tx,
+            outbox: Arc::clone(&outbox),
+            osc52_read: false,
+            palette: crate::palette::Palette::dark(),
+        };
+        let mut proj = AlacrittyProjection::new(GridDims::new(80, 24), listener);
+        proj.advance(b"\x1b]52;c;?\x07");
+        let got = String::from_utf8(outbox.lock().unwrap().clone()).unwrap();
+        assert_eq!(
+            got, "\x1b]52;c;\x07",
+            "an OSC 52 read must reach the listener and get the empty reply, not silence"
+        );
+    }
+
     /// Reconstruct row 0's text from the frame lane until `needle` appears or we
     /// time out. Proves the full path: shell → PTY → engine → projection → lane.
     #[test]

crates/ember-session/src/projection.rs

@@ -12,7 +12,7 @@ use alacritty_terminal::index::{Column, Direction, Line, Point, Side};
 use alacritty_terminal::term::cell::{Cell, Flags};
 use alacritty_terminal::term::search::RegexSearch;
 use alacritty_terminal::term::test::TermSize;
-use alacritty_terminal::term::{Config, Term, TermDamage, TermMode};
+use alacritty_terminal::term::{Config, Osc52, Term, TermDamage, TermMode};
 use alacritty_terminal::vte::ansi::{CursorShape as AlacCursorShape, Processor};
 use ember_core::{
     Attrs, CellContent, CellPatch, CursorShape, CursorState, GridDelta, GridDims, MarkStatus,
@@ -129,7 +129,16 @@ enum Scanned {
 impl<L: EventListener> AlacrittyProjection<L> {
     pub fn new(dims: GridDims, listener: L) -> Self {
         let size = TermSize::new(dims.columns as usize, dims.screen_lines as usize);
-        let term = Term::new(Config::default(), &size, listener);
+        // The engine has its own OSC 52 gate ahead of the listener, and its
+        // default (`OnlyCopy`) drops reads there, so a read would get no reply
+        // at all. Let both through: the listener is the one gate on clipboard
+        // contents (`osc52_read`, off by default = an empty reply), which is
+        // what keeps a well-behaved program from hanging on its query.
+        let config = Config {
+            osc52: Osc52::CopyPaste,
+            ..Config::default()
+        };
+        let term = Term::new(config, &size, listener);
         Self {
             term,
             parser: Processor::new(),