diff --git a/crates/ide-host/src/lib.rs b/crates/ide-host/src/lib.rs
index c1c76fdb..2dad9a5a 100644
--- a/crates/ide-host/src/lib.rs
+++ b/crates/ide-host/src/lib.rs
@@ -349,6 +349,14 @@ impl Host {
         }
     }
 
+    /// Called on desktop exit: kills the runs and terminal shells still alive. Closing a
+    /// window stops what it started, but a quit from the Dock, the app menu or a logout
+    /// exits without closing the windows, and the process trees would outlive the app.
+    pub fn stop_processes_on_exit(&self) {
+        self.processes.kill_all();
+        self.terminals.kill_all();
+    }
+
     /// Called before desktop exit, which may bypass document destructors.
     pub fn clear_workspace_edit_history_on_exit(&self) {
         for project in self.projects() {
diff --git a/crates/ide-run/tests/process.rs b/crates/ide-run/tests/process.rs
index cbb2ba91..21524e4f 100644
--- a/crates/ide-run/tests/process.rs
+++ b/crates/ide-run/tests/process.rs
@@ -529,6 +529,30 @@ fn revoking_one_project_stops_only_its_runs() {
     h.pm.stop(theirs.id).unwrap();
 }
 
+/// Quitting the app kills what every project's runs started, forked children included (#1691).
+#[test]
+fn kill_all_stops_every_projects_process_trees() {
+    let h = harness();
+    let other = tempfile::tempdir().unwrap();
+    let (mine, chunks) = start(&h, &cfg("mine", "/bin/sh", &["-c", "sleep 30 & echo $!; wait"]));
+    let grandchild: i32 = wait_for(&chunks, "\n").trim().parse().expect("pid");
+    let theirs =
+        h.pm.start(
+            other.path(),
+            &cfg("theirs", "/bin/sh", &["-c", "sleep 30"]),
+            &StartOptions::default(),
+            h.sink.clone(),
+            Box::new(|_| {}),
+        )
+        .unwrap();
+    h.pm.kill_all();
+    let deadline = Instant::now() + Duration::from_secs(8);
+    while alive(grandchild) || h.pm.list().iter().any(|r| (r.id == mine || r.id == theirs.id) && r.running) {
+        assert!(Instant::now() < deadline, "a run survived kill_all");
+        std::thread::sleep(Duration::from_millis(50));
+    }
+}
+
 #[test]
 #[ignore = "requires CMake, CTest and a C++ compiler"]
 fn cmake_configure_discovers_builds_and_runs_a_multifile_target() {
diff --git a/src-tauri/src/lib.rs b/src-tauri/src/lib.rs
index 86dc6dc2..9e02a874 100644
--- a/src-tauri/src/lib.rs
+++ b/src-tauri/src/lib.rs
@@ -234,6 +234,7 @@ pub fn run() {
         let _ = &early_opens;
         if let tauri::RunEvent::Exit = event {
             if let Some(state) = app.try_state::<AppState>() {
+                state.host.stop_processes_on_exit();
                 state.host.clear_workspace_edit_history_on_exit();
                 state.host.shutdown_notebooks_on_exit();
             }