diff --git a/src/web/public/tile-grid.js b/src/web/public/tile-grid.js
index dad1aca4..fd4ac15e 100644
--- a/src/web/public/tile-grid.js
+++ b/src/web/public/tile-grid.js
@@ -879,13 +879,15 @@ Object.assign(CodemanApp.prototype, {
       this.showToast?.('This group has no session to show as tiles', 'info');
       return false;
     }
+    // Before the open grid closes (which drops activeSessionId): the session in
+    // focus keeps it if the group holds it, as with the picker's Open.
+    const focus = ids.includes(this.activeSessionId) ? this.activeSessionId : ids[0];
     if (this._tilesOwnTerminal()) {
       this.closeTileGrid({ keepStored: false, reselect: false });
       // As selectSession's tile branch: the parked terminal still holds what it
       // showed before the grid, and re-parking must not snapshot it.
       this.activeSessionId = null;
     }
-    const focus = ids.includes(this.activeSessionId) ? this.activeSessionId : ids[0];
     return this.openTileGrid(ids, { focusedId: focus });
   },
 
diff --git a/test/tile-grid-entry-points.test.ts b/test/tile-grid-entry-points.test.ts
index 59e08567..fe4b56b4 100644
--- a/test/tile-grid-entry-points.test.ts
+++ b/test/tile-grid-entry-points.test.ts
@@ -213,6 +213,28 @@ describe('"Open group as tiles"', () => {
     expect(app._tileGrid.ids).toEqual(['s-c', 's-a']);
   });
 
+  it('keeps the focused session focused when the group holds it, open grid or not', () => {
+    for (const gridOpen of [false, true]) {
+      resetGridHarness();
+      const app = makeGridApp(IDS);
+      withGroups(app);
+      if (gridOpen) app.openTileGrid(['s-b', 's-a'], { focusedId: 's-a' });
+      else app.activeSessionId = 's-a';
+      app.openGroupAsTiles('g1');
+      expect(app._tileGrid.ids).toEqual(['s-c', 's-a']);
+      expect(app._tileGrid.focusedId).toBe('s-a');
+      expect(app.activeSessionId).toBe('s-a');
+    }
+  });
+
+  it("focuses the group's first session when it does not hold the focused one", () => {
+    const app = makeGridApp(IDS);
+    withGroups(app);
+    app.openTileGrid(['s-b']);
+    app.openGroupAsTiles('g1');
+    expect(app._tileGrid.focusedId).toBe('s-c');
+  });
+
   it('is not offered where the grid cannot open', () => {
     const app = makeGridApp(IDS);
     const actions = withGroups(app);