fix: reap detached custom command children (#1384)

* fix: reap detached custom command children

refs #1360

* test: harden child cleanup and sidebar metrics

refs #1360

---------

Co-authored-by: akbash-bot <300245827+akbash-bot@users.noreply.github.com>

3 files changed, 71 insertions, 8 deletions

diff --git a/src/app/input/navigate.rs b/src/app/input/navigate.rs
index a1597669..7f98f530 100644
--- a/src/app/input/navigate.rs
+++ b/src/app/input/navigate.rs
@@ -843,7 +843,7 @@ impl App {
     }
 
     fn spawn_custom_command(
-        &self,
+        &mut self,
         binding: &crate::config::CustomCommandKeybind,
     ) -> std::io::Result<()> {
         let mut command = crate::platform::detached_custom_command_process(&binding.command);
@@ -856,7 +856,8 @@ impl App {
         if let Some(cwd) = cwd {
             command.current_dir(cwd);
         }
-        command.spawn()?;
+        let child = command.spawn()?;
+        self.detached_custom_command_children.push(child);
         Ok(())
     }
 
@@ -2943,9 +2944,11 @@ navigate_pane_down = "ctrl+j"
         app.state.mode = Mode::Terminal;
 
         let output_path = unique_temp_path("custom-command-keybind");
+        let release_path = unique_temp_path("custom-command-release");
         let command = format!(
-            "printf '%s\\n%s\\n%s\\n' \"$HERDR_ACTIVE_WORKSPACE_ID\" \"$HERDR_ACTIVE_TAB_ID\" \"$HERDR_ACTIVE_PANE_ID\" > '{}'",
-            output_path.display()
+            "printf '%s\\n%s\\n%s\\n%s\\n' \"$$\" \"$HERDR_ACTIVE_WORKSPACE_ID\" \"$HERDR_ACTIVE_TAB_ID\" \"$HERDR_ACTIVE_PANE_ID\" > '{}'; i=0; while [ ! -e '{}' ] && [ \"$i\" -lt 250 ]; do sleep 0.02; i=$((i + 1)); done",
+            output_path.display(),
+            release_path.display(),
         );
         app.state.keybinds.custom_commands = vec![crate::config::CustomCommandKeybind {
             bindings: crate::config::ActionKeybinds::prefix("m"),
@@ -2962,18 +2965,48 @@ navigate_pane_down = "ctrl+j"
         .await;
         assert_eq!(app.state.mode, Mode::Prefix);
 
+        let launch_started = std::time::Instant::now();
         app.handle_key(TerminalKey::new(KeyCode::Char('m'), KeyModifiers::empty()))
             .await;
+        assert!(launch_started.elapsed() < Duration::from_secs(2));
 
         let content = wait_for_file(&output_path);
         let lines: Vec<&str> = content.lines().collect();
-        assert_eq!(lines.len(), 3);
-        assert_eq!(lines[0], app.state.workspaces[0].id);
-        assert_eq!(lines[1], format!("{}:t1", app.state.workspaces[0].id));
-        assert_eq!(lines[2], format!("{}:p1", app.state.workspaces[0].id));
+        assert_eq!(lines.len(), 4);
+        let pid = lines[0]
+            .parse::<u32>()
+            .expect("command should report its pid");
+        assert!(crate::platform::process_exists(pid));
+        assert_eq!(lines[1], app.state.workspaces[0].id);
+        assert_eq!(lines[2], format!("{}:t1", app.state.workspaces[0].id));
+        assert_eq!(lines[3], format!("{}:p1", app.state.workspaces[0].id));
         assert_eq!(app.state.mode, Mode::Terminal);
 
+        std::fs::write(&release_path, b"release").expect("release command");
+        let deadline = tokio::time::Instant::now() + Duration::from_secs(2);
+        while crate::platform::process_exists(pid) && tokio::time::Instant::now() < deadline {
+            app.reap_finished_custom_commands();
+            tokio::time::sleep(Duration::from_millis(20)).await;
+        }
+        app.reap_finished_custom_commands();
+        let reaped_by_runtime = !crate::platform::process_exists(pid);
+        if !reaped_by_runtime {
+            if let Some(child) = app
+                .detached_custom_command_children
+                .iter_mut()
+                .find(|child| child.id() == pid)
+            {
+                let _ = child.kill();
+                let _ = child.wait();
+            }
+        }
+        assert!(
+            reaped_by_runtime,
+            "detached command child {pid} was not reaped"
+        );
+
         let _ = std::fs::remove_file(output_path);
+        let _ = std::fs::remove_file(release_path);
     }
 
     #[cfg(unix)]
diff --git a/src/app/mod.rs b/src/app/mod.rs
index bff04c44..16cfeafb 100644
--- a/src/app/mod.rs
+++ b/src/app/mod.rs
@@ -130,6 +130,7 @@ pub struct App {
     pub(crate) selection_highlight_clear_deadline: Option<Instant>,
     pub(crate) session_save_deadline: Option<Instant>,
     pub(crate) session_save_thread: Option<std::thread::JoinHandle<()>>,
+    pub(crate) detached_custom_command_children: Vec<std::process::Child>,
     pub(crate) persist_pane_history: bool,
     pub(crate) last_render_at: Option<Instant>,
     pub(crate) suppressed_repeat_keys:
@@ -725,6 +726,7 @@ impl App {
             pending_agent_resume_deadline: None,
             session_save_deadline: None,
             session_save_thread: None,
+            detached_custom_command_children: Vec::new(),
             selection_autoscroll_deadline: None,
             selection_highlight_clear_deadline: None,
             persist_pane_history: config.experimental.pane_history,
@@ -879,6 +881,7 @@ impl App {
         let mut host_mouse_capture_active = self.state.mouse_capture;
 
         while !self.state.should_quit {
+            self.reap_finished_custom_commands();
             if self.render_dirty.load(Ordering::Acquire) {
                 needs_render = true;
             }
diff --git a/src/app/runtime.rs b/src/app/runtime.rs
index 88081743..25275cd7 100644
--- a/src/app/runtime.rs
+++ b/src/app/runtime.rs
@@ -38,7 +38,27 @@ pub(crate) struct WorkspaceGitRefreshOutput {
     pub(crate) cache_updates: Vec<(std::path::PathBuf, GitStatusCacheEntry)>,
 }
 
+fn retain_custom_command_after_wait(
+    pid: u32,
+    result: std::io::Result<Option<std::process::ExitStatus>>,
+) -> bool {
+    match result {
+        Ok(None) => true,
+        Ok(Some(_)) => false,
+        Err(err) if err.kind() == std::io::ErrorKind::Interrupted => true,
+        Err(err) => {
+            tracing::warn!(pid, err = %err, "failed to reap detached custom command");
+            false
+        }
+    }
+}
+
 impl App {
+    pub(crate) fn reap_finished_custom_commands(&mut self) {
+        self.detached_custom_command_children
+            .retain_mut(|child| retain_custom_command_after_wait(child.id(), child.try_wait()));
+    }
+
     pub(crate) fn shutdown_detached_terminal_runtimes(&mut self) {
         let terminal_ids = std::mem::take(&mut self.state.terminal_runtime_shutdowns);
         for terminal_id in terminal_ids {
@@ -697,6 +717,13 @@ mod tests {
     use crate::workspace::Workspace;
     use std::path::PathBuf;
 
+    #[test]
+    fn interrupted_custom_command_wait_keeps_child_for_retry() {
+        let interrupted = std::io::Error::new(std::io::ErrorKind::Interrupted, "test interrupt");
+
+        assert!(retain_custom_command_after_wait(42, Err(interrupted)));
+    }
+
     fn test_app_with_pane() -> (super::super::App, crate::layout::PaneId) {
         let mut app = super::super::App::new(
             &crate::config::Config::default(),