feat(web): gate sidebar hover preview on ctrl

Plain hover no longer previews — ctrl+hover does.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

web/src/catalog.ts

@@ -663,8 +663,9 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     applyNav();
   };
 
-  // Hover previews the row under the pointer (docs/PREVIEW.md). Touch is left
-  // out: there is no hover there, and a tap already opens the session.
+  // Pointer hover previews only while Ctrl is held — plain hover was too
+  // disruptive when sweeping the sidebar. Keyboard walk (j/k) still previews
+  // unconditionally via applyNav.
   let hovered: string | null = null;
   const setHovered = (id: string | null) => {
     if (hovered === id) return;
@@ -672,7 +673,7 @@ export function renderSidebar(store: CatalogStore, opts: SidebarOptions = {}): S
     opts.onPreview?.(id);
   };
   treeHost.addEventListener("pointerover", (e) => {
-    if (e.pointerType === "touch") return;
+    if (e.pointerType === "touch" || !e.ctrlKey) return;
     const row = (e.target as HTMLElement | null)?.closest<HTMLElement>(".tree-leaf");
     setHovered(row?.dataset.sessionId ?? null);
   });

web/src/sidebarNav.test.ts

@@ -182,26 +182,32 @@ describe("sidebar preview requests (docs/PREVIEW.md)", () => {
     expect(seen.at(-1)).toBe(null);
   });
 
-  it("asks for a preview of the hovered card, and clears it on the way out", () => {
+  it("ctrl+hover previews a card, plain hover does not", () => {
     const seen: (string | null)[] = [];
     const { el } = twoFolders({ onPreview: (id) => seen.push(id) });
     const card = el.querySelectorAll<HTMLElement>(".tree-leaf")[0];
 
+    // Plain hover — no preview.
     card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse" }));
+    expect(seen).toEqual([]);
+
+    // Ctrl+hover — preview fires.
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse", ctrlKey: true }));
     expect(seen).toEqual([A]);
-    // Moving within the same card is not a new preview.
-    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse" }));
+
+    // Deduplicated while still on the same card.
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "mouse", ctrlKey: true }));
     expect(seen).toHaveLength(1);
 
     tree(el).dispatchEvent(new PointerEvent("pointerleave", { pointerType: "mouse" }));
     expect(seen.at(-1)).toBe(null);
   });
 
-  it("ignores touch, where a tap already opens the session", () => {
+  it("ignores touch even with ctrl", () => {
     const seen: (string | null)[] = [];
     const { el } = twoFolders({ onPreview: (id) => seen.push(id) });
     const card = el.querySelectorAll<HTMLElement>(".tree-leaf")[0];
-    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "touch" }));
+    card.dispatchEvent(new PointerEvent("pointerover", { bubbles: true, pointerType: "touch", ctrlKey: true }));
     expect(seen).toEqual([]);
   });
 });