fix: default pane splits to the calling pane (#4123)

2 files changed, 25 insertions, 13 deletions

diff --git a/docs/next/website/src/content/docs/cli-reference.mdx b/docs/next/website/src/content/docs/cli-reference.mdx
index 9d736c39..9f61d02d 100644
--- a/docs/next/website/src/content/docs/cli-reference.mdx
+++ b/docs/next/website/src/content/docs/cli-reference.mdx
@@ -225,8 +225,9 @@ herdr pane close <pane_id>
 
 For pane commands that accept `--current`, Herdr uses the calling pane's
 `HERDR_PANE_ID` when the command runs inside a Herdr pane. For `pane split`,
-an explicit pane id or `--pane ID` splits that pane, `--current` splits the
-calling pane, and an omitted target keeps using the UI-focused pane.
+an explicit pane id or `--pane ID` splits that pane. An omitted target splits
+the calling pane when `HERDR_PANE_ID` is available, otherwise the focused pane.
+`--current` requires a calling pane and errors when `HERDR_PANE_ID` is unavailable.
 The split response exposes the new pane ID as `.result.pane.pane_id`.
 
 `pane input --right-click pane` forwards unmodified right-click gestures to a
diff --git a/src/cli/pane.rs b/src/cli/pane.rs
index 896cee45..3b900e17 100644
--- a/src/cli/pane.rs
+++ b/src/cli/pane.rs
@@ -633,7 +633,7 @@ fn parse_pane_split_args(
 ) -> Result<PaneSplitParams, String> {
     let args = super::expand_equals_args(args, &["--right-click"]);
     let mut env = std::collections::HashMap::new();
-    let mut pane_id = None;
+    let mut pane_id = env_pane_id.map(super::normalize_pane_id);
     let mut direction = None;
     let mut ratio = None;
     let mut cwd = None;
@@ -1783,22 +1783,33 @@ mod tests {
     }
 
     #[test]
-    fn parse_pane_split_args_omitted_target_keeps_focused_fallback() {
-        let params =
-            parse_pane_split_args(&args(&["--direction", "down"]), Some("issue-1")).unwrap();
+    fn parse_pane_split_args_omitted_target_uses_caller() {
+        let params = parse_pane_split_args(
+            &args(&["--no-focus", "--direction", "right", "--cwd", "/var/tmp"]),
+            Some("w1:p2"),
+        )
+        .unwrap();
+
+        assert_eq!(params.target_pane_id, Some("w1:p2".into()));
+        assert!(!params.focus);
+    }
+
+    #[test]
+    fn parse_pane_split_args_without_caller_keeps_focused_fallback() {
+        let params = parse_pane_split_args(&args(&["--direction", "down"]), None).unwrap();
 
         assert_eq!(params.target_pane_id, None);
-        assert_eq!(params.direction, crate::api::schema::SplitDirection::Down);
     }
 
     #[test]
-    fn parse_pane_split_args_accepts_pane_option() {
-        let params =
-            parse_pane_split_args(&args(&["--pane", "issue-2", "--direction", "right"]), None)
-                .unwrap();
+    fn parse_pane_split_args_explicit_target_overrides_caller() {
+        for target in [args(&["w2:p3"]), args(&["--pane", "w2:p3"])] {
+            let mut input = target;
+            input.extend(args(&["--direction", "right"]));
+            let params = parse_pane_split_args(&input, Some("w1:p2")).unwrap();
 
-        assert_eq!(params.target_pane_id, Some("issue-2".into()));
-        assert_eq!(params.direction, crate::api::schema::SplitDirection::Right);
+            assert_eq!(params.target_pane_id, Some("w2:p3".into()));
+        }
     }
 
     #[test]