feat: add per-pane default foreground/background color support (#4737)

* feat: add per-pane default foreground/background color support

Add per-pane default foreground and background colors, configurable
through four surfaces:

- OSC 10/11 escape sequences (set/query) and OSC 110/111 (reset)
- CLI action: zellij action set-pane-color --pane-id <id> --fg/--bg
- Layout config: default_fg/default_bg properties on pane nodes
- Plugin API: set_pane_color() SDK function and PaneInfo read-side

Colors are applied at render time as a fallback when cells have no
explicit foreground/background, without mutating stored grid data.

Closes #4712

* refactor: address review feedback for pane color support

- Extract adjust_styles_for_custom_bg_fg in output/mod.rs
- Move color parsing (xparse_color) from tab into Grid
- Move color serialization (ansi_code_to_color_string) into Grid
- Pane trait now uses Option<String> for color getters/setters
- Add colors to session serialization (dump-layout)
- Add default_fg/default_bg to protobuf IPC schema to fix
  layout-in-session color loss
- Update example layout with tab-bar and status-bar

* fix stack overflow and ordering

* rustfmt

* update e2e snapshots

---------

Co-authored-by: Karl Bunch <karl@karlbunch.com>
Co-authored-by: Aram Drevekenin <aram@poor.dev>

1 files changed, 20 insertions, 1 deletions

diff --git a/zellij-utils/src/plugin_api/plugin_command.rs b/zellij-utils/src/plugin_api/plugin_command.rs
index c3741591..abd9a994 100644
--- a/zellij-utils/src/plugin_api/plugin_command.rs
+++ b/zellij-utils/src/plugin_api/plugin_command.rs
@@ -102,7 +102,7 @@ pub use super::generated_api::api::{
         SaveLayoutPayload, SaveLayoutResponse as ProtobufSaveLayoutResponse, SaveSessionPayload,
         SaveSessionResponse as ProtobufSaveSessionResponse, ScrollDownInPaneIdPayload,
         ScrollToBottomInPaneIdPayload, ScrollToTopInPaneIdPayload, ScrollUpInPaneIdPayload,
-        SetFloatingPanePinnedPayload, SetPaneBorderlessPayload,
+        SetFloatingPanePinnedPayload, SetPaneBorderlessPayload, SetPaneColorPayload,
         SetSelfMouseSelectionSupportPayload, SetTimeoutPayload, ShowCursorPayload,
         ShowFloatingPanesPayload as ProtobufShowFloatingPanesPayload,
         ShowFloatingPanesResponse as ProtobufShowFloatingPanesResponse, ShowPaneWithIdPayload,
@@ -2423,6 +2423,17 @@ impl TryFrom<ProtobufPluginCommand> for PluginCommand {
                 None => Ok(PluginCommand::ShowFloatingPanes { tab_id: None }),
                 _ => Err("Mismatched payload for ShowFloatingPanes"),
             },
+            Some(CommandName::SetPaneColor) => match protobuf_plugin_command.payload {
+                Some(Payload::SetPaneColorPayload(payload)) => match payload.pane_id {
+                    Some(pane_id) => Ok(PluginCommand::SetPaneColor(
+                        pane_id.try_into()?,
+                        payload.fg,
+                        payload.bg,
+                    )),
+                    None => Err("Malformed SetPaneColor payload"),
+                },
+                _ => Err("Mismatched payload for SetPaneColor"),
+            },
             None => Err("Unrecognized plugin command"),
         }
     }
@@ -3975,6 +3986,14 @@ impl TryFrom<PluginCommand> for ProtobufPluginCommand {
                     },
                 )),
             }),
+            PluginCommand::SetPaneColor(pane_id, fg, bg) => Ok(ProtobufPluginCommand {
+                name: CommandName::SetPaneColor as i32,
+                payload: Some(Payload::SetPaneColorPayload(SetPaneColorPayload {
+                    pane_id: Some(pane_id.try_into()?),
+                    fg,
+                    bg,
+                })),
+            }),
         }
     }
 }