fix(render): compact large terminal redraws (#2675)

refs #2670

Co-authored-by: akbash-bot <300245827+akbash-bot@users.noreply.github.com>

2 files changed, 87 insertions, 13 deletions

diff --git a/src/protocol/render_ansi.rs b/src/protocol/render_ansi.rs
index 1e6b9aa4..97685d4d 100644
--- a/src/protocol/render_ansi.rs
+++ b/src/protocol/render_ansi.rs
@@ -633,9 +633,11 @@ fn write_ime_anchor_cursor_state(writer: &mut impl Write, cursor: HostCursorStat
 }
 
 fn write_all_cells(writer: &mut impl Write, frame: &FrameData) {
+    let mut last_sgr = String::new();
     let mut active_hyperlink = None;
     for row in 0..frame.height {
         let mut to_skip = 0usize;
+        let mut next_inline_col = None;
         for col in 0..frame.width {
             if to_skip > 0 {
                 to_skip -= 1;
@@ -646,25 +648,23 @@ fn write_all_cells(writer: &mut impl Write, frame: &FrameData) {
             let cell = &frame.cells[idx];
 
             if cell.skip {
+                next_inline_col = None;
                 continue;
             }
 
-            // Move cursor to position (1-based).
-            let _ = write!(writer, "\x1b[{};{}H", row + 1, col + 1);
-
-            // Set style.
-            let sgr = build_sgr(cell.fg, cell.bg, cell.modifier);
-            let _ = writer.write_all(sgr.as_bytes());
-
-            write_hyperlink_if_changed(
+            let cursor_position = (next_inline_col != Some(col)).then_some((col, row));
+            write_cell(
                 writer,
+                cursor_position,
+                cell,
+                &mut last_sgr,
                 &mut active_hyperlink,
-                cell_hyperlink_uri(frame, cell),
+                frame,
             );
-
-            // Write the symbol.
-            let _ = writer.write_all(cell.symbol.as_bytes());
-            to_skip = cell_width(cell).saturating_sub(1);
+            let width = cell_width(cell);
+            next_inline_col =
+                (cell.symbol.is_ascii() && width == 1).then_some(col.saturating_add(1));
+            to_skip = width.saturating_sub(1);
         }
     }
 
diff --git a/src/server/headless.rs b/src/server/headless.rs
index ff6f367d..7393a7c5 100644
--- a/src/server/headless.rs
+++ b/src/server/headless.rs
@@ -9156,6 +9156,80 @@ next_tab = ""
     }
 
     #[test]
+    fn render_and_stream_sends_large_terminal_frame_for_terminal_ansi_client() {
+        let mut server = test_headless_server();
+        server.app.state.workspaces = vec![crate::workspace::Workspace::test_new("test")];
+        server.app.state.ensure_test_terminals();
+        server.app.state.active = Some(0);
+        server.app.state.selected = 0;
+        server.app.state.mode = crate::app::Mode::Terminal;
+        let (client_tx, _client_control_rx, client_rx) = test_client_writer();
+
+        server.clients.insert(
+            1,
+            ClientConnection::new(
+                (278, 85),
+                crate::kitty_graphics::HostCellSize::default(),
+                crate::terminal_theme::TerminalTheme::default(),
+                None,
+                1,
+                RenderEncoding::TerminalAnsi,
+                Some(client_tx),
+            ),
+        );
+        server.foreground_client_id = Some(1);
+        server.sync_foreground_client_state();
+
+        server.render_and_stream();
+        match read_server_message(
+            client_rx
+                .recv_timeout(Duration::from_millis(100))
+                .expect("initial terminal frame"),
+        ) {
+            ServerMessage::Terminal(frame) => {
+                assert_eq!(frame.seq, 1);
+                assert_eq!((frame.width, frame.height), (278, 85));
+                assert!(frame.full);
+            }
+            other => panic!("expected terminal frame, got {other:?}"),
+        }
+
+        assert!(server.handle_server_event(ServerEvent::ClientResize {
+            client_id: 1,
+            cols: 710,
+            rows: 202,
+            cell_width_px: 0,
+            cell_height_px: 0,
+        }));
+        server.render_and_stream();
+
+        match read_server_message(
+            client_rx
+                .recv_timeout(Duration::from_millis(100))
+                .expect("large terminal frame"),
+        ) {
+            ServerMessage::Terminal(frame) => {
+                assert_eq!(frame.seq, 2);
+                assert_eq!((frame.width, frame.height), (710, 202));
+                assert!(frame.full);
+                assert!(!frame.bytes.is_empty());
+            }
+            other => panic!("expected terminal frame, got {other:?}"),
+        }
+
+        server.app.state.mode = crate::app::Mode::Navigate;
+        server.render_and_stream();
+        match read_server_message(
+            client_rx
+                .recv_timeout(Duration::from_millis(100))
+                .expect("follow-up terminal frame"),
+        ) {
+            ServerMessage::Terminal(frame) => assert_eq!(frame.seq, 3),
+            other => panic!("expected terminal frame, got {other:?}"),
+        }
+    }
+
+    #[test]
     fn terminal_ansi_input_does_not_reset_blit_baseline() {
         let mut server = test_headless_server();
         let (client_tx, _client_control_rx, client_rx) = test_client_writer();