diff --git a/Cargo.lock b/Cargo.lock
index 9f8a29e..d6b5f15 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1922,7 +1922,7 @@ dependencies = [
 [[package]]
 name = "ely-gpui-component"
 version = "0.1.1"
-source = "git+https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components?rev=d126a7e7f7977dddae598486dd99aba79ce1f5f0#d126a7e7f7977dddae598486dd99aba79ce1f5f0"
+source = "git+https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components?rev=e89fb32f43b51c0cd03f6be383dc58796bac19e1#e89fb32f43b51c0cd03f6be383dc58796bac19e1"
 dependencies = [
  "alacritty_terminal",
  "anyhow",
diff --git a/Cargo.toml b/Cargo.toml
index 3185cdc..5de3ad6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -19,7 +19,7 @@ jiff = "0.2"
 anyhow = "1"
 directories = "6"
 dunce = "1"
-ely-gpui-component = { git = "https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components", rev = "d126a7e7f7977dddae598486dd99aba79ce1f5f0" }
+ely-gpui-component = { git = "https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components", rev = "e89fb32f43b51c0cd03f6be383dc58796bac19e1" }
 env_logger = "0.11"
 gpui = { package = "gpui-pre", version = "=0.3.8", default-features = false, features = ["stacker"] }
 gpui_platform = { package = "gpui-pre-platform", version = "=0.3.8", features = ["font-kit", "wayland", "x11"] }
diff --git a/agents.md b/agents.md
index 2a859f1..c496713 100644
--- a/agents.md
+++ b/agents.md
@@ -40,7 +40,7 @@ site/        官网（Vite 8、pnpm、TypeScript，无框架；等轴 SVG 积木
 
 ## 组件映射
 
-依赖 `ely-gpui-component`（pin d126a7e，gpui 为 crates.io 的 `gpui-pre` =0.3.8）。名字取自 `reference/Ely-GPUI-Components/src`。gpui 用法规则见该仓库 `AGENTS.md`。`tests/scripts/agents_md.py` 核对下表每个名字都是组件库公开项。
+依赖 `ely-gpui-component`（pin e89fb32，gpui 为 crates.io 的 `gpui-pre` =0.3.8）。名字取自 `reference/Ely-GPUI-Components/src`。gpui 用法规则见该仓库 `AGENTS.md`。`tests/scripts/agents_md.py` 核对下表每个名字都是组件库公开项。
 
 | 需要 | 用 |
 | --- | --- |
diff --git a/apps/ely-mark/src/compare.rs b/apps/ely-mark/src/compare.rs
index 4b0097b..bb4aaee 100644
--- a/apps/ely-mark/src/compare.rs
+++ b/apps/ely-mark/src/compare.rs
@@ -190,3 +190,36 @@ enum Choice {
     Mine,
     Merged,
 }
+
+#[cfg(test)]
+mod tests {
+    use gpui::TestAppContext;
+
+    use super::Choice;
+    use crate::outside::tests::{look, opened, shown};
+
+    #[gpui::test]
+    fn a_merge_lands_as_one_undo_step(cx: &mut TestAppContext) {
+        let (desk, cx, id, path, _dirs) = opened("a\n\nb\n", cx);
+        let view = desk.read_with(cx, |desk, _| desk.active_view().expect("a tab"));
+        view.update(cx, |view, cx| view.adopt("a\n\nb\n\nmine\n".into(), cx));
+        cx.run_until_parked();
+        std::fs::write(&path, "theirs\n\na\n\nb\n").expect("an outside write");
+        look(&desk, id, cx);
+        desk.update(cx, |desk, cx| desk.compare(id, cx));
+        desk.update_in(cx, |desk, window, cx| {
+            desk.settle(Choice::Merged, window, cx)
+        });
+        cx.run_until_parked();
+        assert_eq!(shown(&desk, cx), "theirs\n\na\n\nb\n\nmine\n");
+        let focus = view.read_with(cx, |view, _| view.focus.clone());
+        cx.update(|window, cx| window.focus(&focus, cx));
+        cx.run_until_parked();
+        cx.simulate_keystrokes("secondary-z");
+        assert_eq!(
+            shown(&desk, cx),
+            "a\n\nb\n\nmine\n",
+            "one undo takes the merge back"
+        );
+    }
+}
diff --git a/apps/ely-mark/src/outside.rs b/apps/ely-mark/src/outside.rs
index 025800d..c8c08a9 100644
--- a/apps/ely-mark/src/outside.rs
+++ b/apps/ely-mark/src/outside.rs
@@ -403,27 +403,4 @@ fn watch(dirs: &[PathBuf], cx: &mut Context<Desk>) -> notify::Result<Recommended
 }
 
 #[cfg(test)]
-mod tests {
-    use std::time::{Duration, Instant};
-
-    use ely_files::Action;
-
-    use super::Extra;
-
-    #[test]
-    fn a_restarted_autosave_saves_the_next_edit() {
-        let mut extra = Extra::default();
-        extra.policy.set_has_path();
-        extra.policy.edit(Instant::now());
-        // A write was in flight when the disk changed.
-        extra.writing = Some(1);
-        extra.restart_autosave();
-        // As autosave settles a heard write, then edits.
-        if let Some(revision) = extra.writing.take() {
-            extra.policy.save_finished(revision, true);
-        }
-        let now = Instant::now();
-        extra.policy.edit(now);
-        assert!(matches!(extra.policy.tick(now + Duration::from_secs(5)), Action::SaveDue(_)));
-    }
-}
+pub(crate) mod tests;
diff --git a/apps/ely-mark/src/outside/tests.rs b/apps/ely-mark/src/outside/tests.rs
new file mode 100644
index 0000000..79bf613
--- /dev/null
+++ b/apps/ely-mark/src/outside/tests.rs
@@ -0,0 +1,140 @@
+use std::{
+    path::PathBuf,
+    time::{Duration, Instant},
+};
+
+use ely_files::Action;
+use ely_office::prelude::*;
+use gpui::{Entity, TestAppContext, VisualTestContext};
+
+use super::{Extra, GAP, Outside};
+use crate::desk::{
+    Desk,
+    tests::{open, start},
+};
+
+#[test]
+fn a_restarted_autosave_saves_the_next_edit() {
+    let mut extra = Extra::default();
+    extra.policy.set_has_path();
+    extra.policy.edit(Instant::now());
+    // A write was in flight when the disk changed.
+    extra.writing = Some(1);
+    extra.restart_autosave();
+    // As autosave settles a heard write, then edits.
+    if let Some(revision) = extra.writing.take() {
+        extra.policy.save_finished(revision, true);
+    }
+    let now = Instant::now();
+    extra.policy.edit(now);
+    assert!(matches!(
+        extra.policy.tick(now + Duration::from_secs(5)),
+        Action::SaveDue(_)
+    ));
+}
+
+/// A saved file open: its desk, tab and path.
+pub(crate) fn opened(
+    text: &str,
+    cx: &mut TestAppContext,
+) -> (
+    Entity<Desk>,
+    &'static mut VisualTestContext,
+    u64,
+    PathBuf,
+    [tempfile::TempDir; 2],
+) {
+    let (data, files) = (
+        tempfile::tempdir().expect("data"),
+        tempfile::tempdir().expect("files"),
+    );
+    let path = files.path().join("a.md");
+    std::fs::write(&path, text).expect("a file");
+    let (desk, cx) = start(cx, data.path());
+    open(&desk, &path, cx);
+    let id = desk.read_with(cx, |desk, _| desk.core.active.expect("a tab"));
+    (desk, cx, id, path, [data, files])
+}
+
+/// The desk looks at the file, as the watcher would.
+pub(crate) fn look(desk: &Entity<Desk>, id: u64, cx: &mut VisualTestContext) {
+    desk.update(cx, |desk, cx| desk.look(id, cx));
+    cx.run_until_parked();
+    cx.executor().advance_clock(GAP * 2);
+    cx.run_until_parked();
+}
+
+pub(crate) fn shown(desk: &Entity<Desk>, cx: &mut VisualTestContext) -> String {
+    desk.read_with(cx, |desk, cx| {
+        let view = desk.active_view().expect("a tab");
+        view.read(cx).document().read(cx).text(cx)
+    })
+}
+
+#[gpui::test]
+fn a_clean_tab_takes_the_disk_and_keeps_its_place(cx: &mut TestAppContext) {
+    let (desk, cx, id, path, _dirs) = opened("one\n\ntwo\n\nthree\n", cx);
+    let view = desk.read_with(cx, |desk, _| desk.active_view().expect("a tab"));
+    let document = view.read_with(cx, |view, _| view.document().clone());
+    document.update(cx, |document, cx| document.set_caret(4, 2, cx));
+    std::fs::write(&path, "uno\n\ndos\n\ntres, longer\n").expect("an outside write");
+    look(&desk, id, cx);
+    assert_eq!(shown(&desk, cx), "uno\n\ndos\n\ntres, longer\n");
+    assert!(!view.read_with(cx, |view, _| view.modified()));
+    assert_eq!(
+        document.read_with(cx, |document, cx| document.caret(cx)),
+        (4, 2)
+    );
+    let focus = view.read_with(cx, |view, _| view.focus.clone());
+    cx.update(|window, cx| window.focus(&focus, cx));
+    cx.run_until_parked();
+    cx.simulate_keystrokes("secondary-z");
+    assert_eq!(
+        shown(&desk, cx),
+        "uno\n\ndos\n\ntres, longer\n",
+        "undo stops at the disk"
+    );
+}
+
+#[gpui::test]
+fn a_deleted_file_keeps_its_text_and_says_so(cx: &mut TestAppContext) {
+    let (desk, cx, id, path, _dirs) = opened("kept\n", cx);
+    std::fs::remove_file(&path).expect("deleted");
+    look(&desk, id, cx);
+    let deleted = desk.read_with(cx, |desk, _| {
+        matches!(desk.tab(id).expect("open").extra.outside, Outside::Deleted)
+    });
+    assert!(deleted);
+    assert_eq!(shown(&desk, cx), "kept\n");
+}
+
+#[gpui::test]
+fn a_renamed_file_is_followed(cx: &mut TestAppContext) {
+    let (desk, cx, id, path, _dirs) = opened("moved\n", cx);
+    let to = path.with_file_name("b.md");
+    std::fs::rename(&path, &to).expect("renamed");
+    look(&desk, id, cx);
+    let now = desk.read_with(cx, |desk, _| {
+        desk.tab(id)
+            .and_then(|tab| tab.session.path().map(PathBuf::from))
+    });
+    assert_eq!(
+        now.map(|path| path.file_name().map(ToOwned::to_owned)),
+        Some(Some("b.md".into()))
+    );
+}
+
+#[gpui::test]
+fn a_path_that_cannot_be_read_says_why(cx: &mut TestAppContext) {
+    let (desk, cx, id, path, _dirs) = opened("text\n", cx);
+    std::fs::remove_file(&path).expect("removed");
+    std::fs::create_dir(&path).expect("a folder in its place");
+    look(&desk, id, cx);
+    let unread = desk.read_with(cx, |desk, _| {
+        matches!(
+            desk.tab(id).expect("open").extra.outside,
+            Outside::Unread(_)
+        )
+    });
+    assert!(unread);
+}
diff --git a/scripts/fetch-references.sh b/scripts/fetch-references.sh
index 17f3f37..606ed04 100755
--- a/scripts/fetch-references.sh
+++ b/scripts/fetch-references.sh
@@ -36,7 +36,7 @@ fetch() { # name url rev [sparse paths...]
   echo "fetch $name $rev"
 }
 
-fetch Ely-GPUI-Components https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components.git d126a7e7f7977dddae598486dd99aba79ce1f5f0
+fetch Ely-GPUI-Components https://git.zacharyzhang.com/ZacharyZhang-NY/Ely-GPUI-Components.git e89fb32f43b51c0cd03f6be383dc58796bac19e1
 fetch zed https://github.com/zed-industries/zed.git 1a28cff4b409169bac058bca40dfbfeb7621d19b
 fetch libreoffice-core https://github.com/LibreOffice/core.git 8221e31b3ac356a1623c672912a3d2b492f7e3d1 \
   include/LibreOfficeKit libreofficekit desktop/source/lib desktop/inc \