fix: respect --name flag when creating new panes (#4979)

* fix: respect --name flag when creating and renaming panes

Three issues fixed:

1. Pane creation: --name was silently discarded for default shell panes
   because use_terminal_title was true. Now user-provided names take
   priority. Also pass initial_pane_title as pane_name to TerminalPane
   constructor (was hardcoded to empty string).

2. CLI rename without --pane-id: was routed through PaneNameInput which
   appends to existing name. Now uses a dedicated RenameActivePane action
   that fully replaces the name, working for any name length including
   single characters.

3. Interactive rename: entering rename mode preserves the existing name
   for editing (append/backspace). Esc reverts to the name before rename
   mode was entered.

Adds 28 tests covering rename semantics, interactive editing, undo,
OSC title interaction, and a wire-level IPC round-trip test.

* refactor: route active-pane rename via Option<PaneId>

Replace the dedicated Action::RenameActivePane variant with an
Option<PaneId> on the existing Action::RenamePaneByPaneId. route.rs
dispatches None to the server-internal ScreenInstruction::RenameActivePane
and Some(id) to the existing RenamePaneWithPaneId path.

Drops all proto/conversion boilerplate for the removed variant: plugin
API additions, IPC tag 137, and both directions of the wire conversion.

---------

Co-authored-by: divens <divens.dev@gmail.com>

4 files changed, 85 insertions, 27 deletions

diff --git a/zellij-utils/src/errors.rs b/zellij-utils/src/errors.rs
index 0df851c4..d44a348a 100644
--- a/zellij-utils/src/errors.rs
+++ b/zellij-utils/src/errors.rs
@@ -352,6 +352,7 @@ pub enum ScreenContext {
     UnsuppressOrExpandPane,
     FocusPaneWithId,
     RenamePane,
+    RenameActivePane,
     RenameTab,
     RequestPluginPermissions,
     BreakPane,
diff --git a/zellij-utils/src/input/actions.rs b/zellij-utils/src/input/actions.rs
index 0ce1c507..ab4c9ae3 100644
--- a/zellij-utils/src/input/actions.rs
+++ b/zellij-utils/src/input/actions.rs
@@ -609,7 +609,7 @@ pub enum Action {
         pane_id: PaneId,
     },
     RenamePaneByPaneId {
-        pane_id: PaneId,
+        pane_id: Option<PaneId>,
         name: Vec<u8>,
     },
     UndoRenamePaneByPaneId {
@@ -1323,23 +1323,19 @@ impl Action {
                 },
                 None => Ok(vec![Action::CloseFocus]),
             },
-            CliAction::RenamePane { name, pane_id } => match pane_id {
-                Some(pane_id_str) => {
-                    let pane_id = PaneId::from_str(&pane_id_str)
-                        .map_err(|_| format!(
+            CliAction::RenamePane { name, pane_id } => {
+                let pane_id = match pane_id {
+                    Some(pane_id_str) => Some(
+                        PaneId::from_str(&pane_id_str).map_err(|_| format!(
                             "Malformed pane id: {pane_id_str}, expecting either a bare integer (eg. 1), a terminal pane id (eg. terminal_1) or a plugin pane id (eg. plugin_1)"
-                        ))?;
-                    Ok(vec![Action::RenamePaneByPaneId {
-                        pane_id,
-                        name: name.as_bytes().to_vec(),
-                    }])
-                },
-                None => Ok(vec![
-                    Action::UndoRenamePane,
-                    Action::PaneNameInput {
-                        input: name.as_bytes().to_vec(),
-                    },
-                ]),
+                        ))?,
+                    ),
+                    None => None,
+                };
+                Ok(vec![Action::RenamePaneByPaneId {
+                    pane_id,
+                    name: name.as_bytes().to_vec(),
+                }])
             },
             CliAction::UndoRenamePane { pane_id } => match pane_id {
                 Some(pane_id_str) => {
@@ -2899,7 +2895,7 @@ mod tests {
         assert_eq!(actions.len(), 1);
         match &actions[0] {
             Action::RenamePaneByPaneId { pane_id, name } => {
-                assert!(matches!(pane_id, PaneId::Terminal(19)));
+                assert!(matches!(pane_id, Some(PaneId::Terminal(19))));
                 assert_eq!(name, &"my-pane".as_bytes().to_vec());
             },
             _ => panic!("Expected RenamePaneByPaneId action"),
@@ -2915,9 +2911,14 @@ mod tests {
         let result = Action::actions_from_cli(cli_action, Box::new(|| PathBuf::from("/tmp")), None);
         assert!(result.is_ok());
         let actions = result.unwrap();
-        assert_eq!(actions.len(), 2);
-        assert!(matches!(actions[0], Action::UndoRenamePane));
-        assert!(matches!(actions[1], Action::PaneNameInput { .. }));
+        assert_eq!(actions.len(), 1);
+        match &actions[0] {
+            Action::RenamePaneByPaneId { pane_id, name } => {
+                assert!(pane_id.is_none());
+                assert_eq!(name, &"my-pane".as_bytes().to_vec());
+            },
+            _ => panic!("Expected RenamePaneByPaneId action"),
+        }
     }
 
     // 18. UndoRenamePane
diff --git a/zellij-utils/src/ipc/protobuf_conversion.rs b/zellij-utils/src/ipc/protobuf_conversion.rs
index 189c1370..656ef54c 100644
--- a/zellij-utils/src/ipc/protobuf_conversion.rs
+++ b/zellij-utils/src/ipc/protobuf_conversion.rs
@@ -1725,7 +1725,7 @@ impl From<crate::input::actions::Action>
             },
             crate::input::actions::Action::RenamePaneByPaneId { pane_id, name } => {
                 ActionType::RenamePaneByPaneId(RenamePaneByPaneIdAction {
-                    pane_id: Some(pane_id.into()),
+                    pane_id: pane_id.map(|id| id.into()),
                     name,
                 })
             },
@@ -2641,10 +2641,7 @@ impl TryFrom<crate::client_server_contract::client_server_contract::Action>
             },
             ActionType::RenamePaneByPaneId(a) => {
                 Ok(crate::input::actions::Action::RenamePaneByPaneId {
-                    pane_id: a
-                        .pane_id
-                        .ok_or_else(|| anyhow!("RenamePaneByPaneId missing pane_id"))?
-                        .try_into()?,
+                    pane_id: a.pane_id.map(|p| p.try_into()).transpose()?,
                     name: a.name,
                 })
             },
diff --git a/zellij-utils/src/ipc/tests/roundtrip_tests.rs b/zellij-utils/src/ipc/tests/roundtrip_tests.rs
index 7ef7ac89..23b8c4ac 100644
--- a/zellij-utils/src/ipc/tests/roundtrip_tests.rs
+++ b/zellij-utils/src/ipc/tests/roundtrip_tests.rs
@@ -1481,6 +1481,24 @@ fn test_client_messages() {
         is_cli_client: true,
     });
     test_client_roundtrip!(ClientToServerMsg::Action {
+        action: Action::RenamePaneByPaneId {
+            pane_id: None,
+            name: "spark".as_bytes().to_vec(),
+        },
+        terminal_id: Some(1),
+        client_id: Some(100),
+        is_cli_client: true,
+    });
+    test_client_roundtrip!(ClientToServerMsg::Action {
+        action: Action::RenamePaneByPaneId {
+            pane_id: None,
+            name: "x".as_bytes().to_vec(),
+        },
+        terminal_id: Some(1),
+        client_id: Some(100),
+        is_cli_client: true,
+    });
+    test_client_roundtrip!(ClientToServerMsg::Action {
         action: Action::NewTab {
             tiled_layout: None,
             floating_layouts: vec![],
@@ -3449,7 +3467,7 @@ fn test_client_messages() {
     });
     test_client_roundtrip!(ClientToServerMsg::Action {
         action: Action::RenamePaneByPaneId {
-            pane_id: PaneId::Terminal(1),
+            pane_id: Some(PaneId::Terminal(1)),
             name: "test-name".as_bytes().to_vec(),
         },
         terminal_id: Some(1),
@@ -3694,3 +3712,44 @@ fn set_pane_color_wire_roundtrip() {
 
     assert_eq!(original, roundtrip);
 }
+
+/// Tests that RenamePaneByPaneId with `pane_id: None` (the active-pane CLI
+/// rename case) survives a full wire-level round-trip
+/// (Rust → proto struct → bytes → proto struct → Rust).
+///
+/// The struct-level round-trip in `test_client_roundtrip!` doesn't catch
+/// issues with prost's `tags` attribute on oneof fields, because prost
+/// only uses the tags list during byte decoding, not struct-to-struct
+/// conversion.
+#[test]
+fn rename_active_pane_wire_roundtrip() {
+    use prost::Message;
+
+    let original = ClientToServerMsg::Action {
+        action: Action::RenamePaneByPaneId {
+            pane_id: None,
+            name: "x".as_bytes().to_vec(),
+        },
+        terminal_id: Some(1),
+        client_id: Some(100),
+        is_cli_client: true,
+    };
+
+    // Rust → proto struct
+    let proto: crate::client_server_contract::client_server_contract::ClientToServerMsg =
+        original.clone().into();
+
+    // proto struct → bytes → proto struct (the actual wire path)
+    let mut buf = Vec::new();
+    proto.encode(&mut buf).expect("Failed to encode protobuf");
+    let decoded =
+        crate::client_server_contract::client_server_contract::ClientToServerMsg::decode(&buf[..])
+            .expect("Failed to decode protobuf bytes");
+
+    // proto struct → Rust
+    let roundtrip: ClientToServerMsg = decoded
+        .try_into()
+        .expect("Failed to convert decoded protobuf back to Rust");
+
+    assert_eq!(original, roundtrip);
+}