Feature: allow overriding a layout for a currently running tab (change layout at runtime) (#4566)

* add tests for LayoutApplier

* initial untested implementation of override functions

* add override-layout cli action with stub in screen

* filter run instructions to ignore

* implement override-layout roundtrip through plugin and pty threads

* initial full-cycle working override implementation

* fix some bugs (eg. actually start new terminals)

* fix some bugs with focus after override

* fix floating pane matching bug in layout applier

* formatting

* use first tab, error on more than 1 tab

* fix some floating_panes ordering and shell issues

* get new tab name to work

* respect swap layouts

* allow specifying tab properties on main layout node if we just have one tab

* add tests for new override methods

* start work on retaining panes, hard-coded things, kind of working but broken in many places

* fixed most tiled pane override bugs

* reset viewport before reapplying

* revert constraint system changes

* retain-existing-terminal-panes flag

* add retain terminal panes tests

* add retain plugin panes flag

* add keybind

* add retain plugin panes tests

* add override-layout e2e test

* refactor: layout_applier

* style: rustfmt

* some cleanups

* fix cli flags

* no crashy

* formatting and artifacts

* moar cleanups

* fix: respect expanded in stack when overriding

* docs(changelog): add PR

3 files changed, 90 insertions, 0 deletions

diff --git a/src/tests/e2e/cases.rs b/src/tests/e2e/cases.rs
index eab81039..f7d9ea0d 100644
--- a/src/tests/e2e/cases.rs
+++ b/src/tests/e2e/cases.rs
@@ -2646,6 +2646,7 @@ pub fn pin_floating_panes() {
     let last_snapshot = account_for_races_in_snapshot(last_snapshot);
     assert_snapshot!(last_snapshot);
 }
+
 #[test]
 #[ignore]
 pub fn watcher_client_functionality() {
@@ -2849,3 +2850,51 @@ pub fn watcher_client_functionality() {
     assert_snapshot!(main_client_snapshot);
     assert_snapshot!(watcher_snapshot);
 }
+
+#[test]
+#[ignore]
+pub fn override_layout_from_default_to_compact() {
+    let fake_win_size = Size {
+        cols: 120,
+        rows: 24,
+    };
+    let mut test_attempts = 10;
+    let last_snapshot = loop {
+        RemoteRunner::kill_running_sessions(fake_win_size);
+
+        let mut runner = RemoteRunner::new(fake_win_size)
+            .add_step(Step {
+                name: "Wait for default layout to load",
+                instruction: |remote_terminal: RemoteTerminal| -> bool {
+                    remote_terminal.status_bar_appears()
+                },
+            })
+            .add_step(Step {
+                name: "Override to compact layout",
+                instruction: |mut remote_terminal: RemoteTerminal| -> bool {
+                    remote_terminal.run_zellij_action("override-layout compact");
+                    std::thread::sleep(std::time::Duration::from_millis(500));
+                    remote_terminal.send_key(&ENTER);
+                    true
+                },
+            });
+
+        runner.run_all_steps();
+        let last_snapshot = runner.take_snapshot_after(Step {
+            name: "Wait for compact layout to appear",
+            instruction: |remote_terminal: RemoteTerminal| -> bool {
+                remote_terminal.snapshot_contains("NORMAL")
+            },
+        });
+
+        if runner.test_timed_out && test_attempts > 0 {
+            test_attempts -= 1;
+            continue;
+        } else {
+            break last_snapshot;
+        }
+    };
+
+    let last_snapshot = account_for_races_in_snapshot(last_snapshot);
+    assert_snapshot!(last_snapshot);
+}
diff --git a/src/tests/e2e/remote_runner.rs b/src/tests/e2e/remote_runner.rs
index 377869f9..d4663ac5 100644
--- a/src/tests/e2e/remote_runner.rs
+++ b/src/tests/e2e/remote_runner.rs
@@ -419,6 +419,19 @@ impl RemoteTerminal {
         channel.flush().unwrap();
         std::thread::sleep(std::time::Duration::from_secs(1)); // wait until Zellij stops parsing startup ANSI codes from the terminal STDIN
     }
+    pub fn run_zellij_action(&mut self, action_and_arguments: &str) {
+        let mut channel = self.channel.lock().unwrap();
+        channel
+            .write_all(
+                format!(
+                    "{} action {}",
+                    ZELLIJ_EXECUTABLE_LOCATION, action_and_arguments
+                )
+                .as_bytes(),
+            )
+            .unwrap();
+        channel.flush().unwrap();
+    }
     pub fn send_command_through_the_cli(&mut self, command: &str) {
         let mut channel = self.channel.lock().unwrap();
         channel
diff --git a/src/tests/e2e/snapshots/zellij__tests__e2e__cases__override_layout_from_default_to_compact.snap b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__override_layout_from_default_to_compact.snap
new file mode 100644
index 00000000..48724fb5
--- /dev/null
+++ b/src/tests/e2e/snapshots/zellij__tests__e2e__cases__override_layout_from_default_to_compact.snap
@@ -0,0 +1,28 @@
+---
+source: src/tests/e2e/cases.rs
+expression: last_snapshot
+---
+┌ Pane #1 ─────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
+│$ /usr/src/zellij/x86_64-unknown-linux-musl/release/zellij action override-layout compact                             │
+│$                                                                                                                     │
+│$ █                                                                                                                   │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
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+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+│                                                                                                                      │
+└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
+ Zellij (e2e-test) NORMAL  Tab #1 