feat: support multiple prefix keys (#4653)

* feat: support multiple prefix keys

keys.prefix accepts an array in addition to a single string so one
config can define several prefix keys. Every configured prefix enters
the same prefix mode, and the help panel lists them all.

Published keybinding profiles keep the primary prefix as a scalar and
carry the rest in an optional extra_prefixes field so older clients
keep working with the primary prefix.

* fix: reject an empty prefix list on reload

An explicitly empty keys.prefix array now stays empty through config
parsing so validation rejects it and a reload keeps the current
keybindings instead of silently falling back to ctrl+b.

1 files changed, 40 insertions, 5 deletions

diff --git a/src/config.rs b/src/config.rs
index 60a22a1e..8550097d 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -17,9 +17,9 @@ pub use self::{
         upsert_section_value,
     },
     keybinds::{
-        format_key_combo, normalize_key_combo, terminal_key_matches_combo, ActionKeybinds,
+        format_prefix_combos, normalize_key_combo, terminal_key_matches_combo, ActionKeybinds,
         BindingConfig, CommandKeybindConfig, CustomCommandAction, CustomCommandKeybind,
-        IndexedKeybind, Keybinds, LiveKeybindConfig,
+        IndexedKeybind, KeyCombo, Keybinds, LiveKeybindConfig,
     },
     model::{
         validated_sidebar_bounds, AgentPanelSortConfig, Config, ConfigReloadReport,
@@ -102,7 +102,7 @@ impl Config {
             .unwrap_or(true)
     }
 
-    pub fn prefix_key(&self) -> (KeyCode, KeyModifiers) {
+    pub fn prefix_keys(&self) -> Vec<(KeyCode, KeyModifiers)> {
         self.validated_keybinds().1
     }
 
@@ -182,7 +182,7 @@ impl Config {
         }
 
         let mut keys = self.keys.local_profile(&self.keybinds());
-        keys.set_prefix(format_key_combo(self.prefix_key()));
+        keys.set_prefixes(&self.prefix_keys());
         toml::to_string_pretty(&KeysProfile { keys })
     }
 }
@@ -239,7 +239,42 @@ prefix = "ctrl+"
         let keybinds = keybindings_from_profile_toml(&profile).unwrap();
 
         assert!(profile.contains("prefix = \"ctrl+b\""));
-        assert_eq!(keybinds.prefix, config.prefix_key());
+        assert_eq!(keybinds.prefix, config.prefix_keys());
+    }
+
+    #[test]
+    fn local_keybindings_profile_publishes_additional_prefixes_for_old_clients() {
+        let config: Config = toml::from_str(
+            r#"
+[keys]
+prefix = ["ctrl+space", "ctrl+s"]
+"#,
+        )
+        .unwrap();
+
+        let profile = config.local_keybindings_profile_toml().unwrap();
+
+        // Generation-1 clients parse `prefix` as a single string; the extra
+        // prefixes ride in the optional `extra_prefixes` field they ignore.
+        assert!(profile.contains("prefix = \"ctrl+space\""));
+        assert!(!profile.contains("prefix = ["));
+        assert!(profile.contains("extra_prefixes = [\"ctrl+s\"]"));
+
+        let keybinds = keybindings_from_profile_toml(&profile).unwrap();
+        assert_eq!(keybinds.prefix, config.prefix_keys());
+    }
+
+    #[test]
+    fn local_keybindings_profile_omits_extra_prefixes_for_a_single_prefix() {
+        let config: Config = toml::from_str(
+            r#"
+[keys]
+prefix = "ctrl+b"
+"#,
+        )
+        .unwrap();
+        let profile = config.local_keybindings_profile_toml().unwrap();
+        assert!(!profile.contains("extra_prefixes"));
     }
 
     #[test]