fix(studio): keep narrow timeline headers readable (#4232)

* fix(studio): hide narrow timeline header labels

* test(studio): cover narrow automation headers

* test(studio): cover narrow automation headers

* test(studio): assert narrow lane tooltip

* style(studio): format narrow header changes

* test(studio): cover narrow speed lane labels

* fix(studio): truncate timeline header names

* test(studio): remove stale header room plumbing

packages/studio/src/player/components/LayerDisclosureRow.tsx

@@ -95,9 +95,9 @@ export function LayerDisclosureRow({
       <span aria-hidden="true" className="shrink-0 text-[13px] leading-none text-white/40">
         ◇
       </span>
-      {/* Wraps rather than truncating: a truncated name needs a hover to be
-          read, which a scanned column cannot rely on. */}
-      <span className="min-w-0 flex-1 wrap-break-word font-medium leading-tight">{name}</span>
+      <span title={name} className="min-w-0 flex-1 truncate font-medium leading-tight">
+        {name}
+      </span>
       <TrackClipCount clipCount={clipCount} />
       {children}
       {/* Anchored right, on every header that has one: the lane toggle is the

packages/studio/src/player/components/TimelineGroupHeader.tsx

@@ -65,9 +65,9 @@ function GroupNameButton({
       <span aria-hidden="true" className="shrink-0 text-[12px] leading-none text-white/50">
         ▤
       </span>
-      {/* Wraps rather than truncating — a name that needs a hover to be read
-          is no use in a column you scan. */}
-      <span className="min-w-0 wrap-break-word text-left font-medium leading-tight">{label}</span>
+      <span title={label} className="min-w-0 truncate text-left font-medium leading-tight">
+        {label}
+      </span>
       <span
         className="shrink-0 rounded-full bg-white/10 px-1 text-[9px] leading-[14px] tabular-nums text-white/55"
         aria-hidden="true"
@@ -109,9 +109,7 @@ export function TimelineGroupHeader({
       }}
     >
       {/* One line, like a track header's: caret and name, then every control
-          anchored to the right edge. The name wraps and the controls are
-          `shrink-0`, so they hold the edge and the name gives way — no second
-          line needed to keep five controls off the label. */}
+          anchored to the right edge. */}
       <button
         type="button"
         tabIndex={-1}

packages/studio/src/player/components/TimelineTrackPlainHeader.test.tsx

@@ -136,4 +136,14 @@ describe("PlainTrackHeader", () => {
     expect(labelOf(view.host)).toBe("Hide track 1");
     view.unmount();
   });
+
+  it("truncates long names and keeps the full name in the tooltip", () => {
+    const name = "A-very-long-unbroken-clip-name-for-the-timeline";
+    const view = renderHeader({ trackLabel: name });
+    const label = view.host.querySelector("span[title]");
+    expect(label?.className).toContain("truncate");
+    expect(label?.className).not.toContain("wrap-break-word");
+    expect(label?.getAttribute("title")).toBe(name);
+    view.unmount();
+  });
 });

packages/studio/src/player/components/TimelineTrackPlainHeader.tsx

@@ -93,14 +93,11 @@ export function PlainTrackHeader({
         )}
         {/* No `flex-1`: the name takes only the width it needs, so the clip
             count sits against it rather than being pushed out to meet the
-            controls. The slack goes to the `ml-auto` group below instead.
-
-            Wraps rather than truncating: a truncated name needs a hover to be
-            read at all, and a tooltip is no use to a name you are scanning a
-            column of. `wrap-break-word` so a long single token breaks instead of
-            forcing the column wider. */}
+            controls. The slack goes to the `ml-auto` group below instead. */}
         {showTrackLabel && (
-          <span className="min-w-0 wrap-break-word text-[11px] leading-tight">{trackLabel}</span>
+          <span title={trackLabel} className="min-w-0 truncate text-[11px] leading-tight">
+            {trackLabel}
+          </span>
         )}
         {showTrackLabel && <TrackClipCount clipCount={clipCount} />}
         {/* `ml-auto` is what anchors the group right: it absorbs the slack the