fix(app): unmount hidden session panes (#35628)

Author: Hona

packages/app/e2e/regression/review-terminal-stacked.spec.ts

@@ -168,8 +168,8 @@ test("keeps the review tree and terminal sized when both panels are open", async
   await expectTree(page, 2_773, "action.yml")
 
   await page.getByRole("button", { name: "Toggle file tree" }).click()
-  await expect(page.locator('[data-slot="session-review-v2-sidebar"]')).toHaveAttribute("aria-hidden", "true")
-  await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(1)
+  await expect(page.locator('[data-slot="session-review-v2-sidebar"]')).toHaveCount(0)
+  await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(0)
   await page.getByRole("button", { name: "Toggle file tree" }).click()
   await expectTree(page, 2_773, "action.yml")
 
@@ -181,8 +181,7 @@ test("keeps the review tree and terminal sized when both panels are open", async
   await expectTree(page, 2_773, "action.yml")
 
   await page.getByRole("button", { name: "Toggle review" }).click()
-  await expect(page.locator("#review-panel")).toHaveAttribute("aria-hidden", "true")
-  await expect(page.locator('#review-panel [data-component="file-tree-v2"]')).toHaveCount(1)
+  await expect(page.locator("#review-panel")).toHaveCount(0)
   await page.getByRole("button", { name: "Toggle review" }).click()
   await expectTree(page, 2_773, "action.yml")
   await page.setViewportSize({ width: 1_000, height: 700 })

packages/app/src/pages/session.tsx

@@ -2198,7 +2198,7 @@ export default function Page() {
           </Show>
         </div>
 
-        <Show when={!newSessionDesign()}>
+        <Show when={!newSessionDesign() && desktopSidePanelOpen()}>
           <SessionSidePanel
             canReview={canReview}
             diffs={reviewDiffs}
@@ -2217,13 +2217,8 @@ export default function Page() {
         <Show when={newSessionDesign()}>
           <Show when={isDesktop() ? desktopV2PanelLayout().visible : terminalOpen()}>
             <div class="min-w-0 h-full flex flex-1 flex-col">
-              <Show when={isDesktop()}>
-                <div
-                  classList={{
-                    "min-h-0 flex-1": desktopV2ReviewOpen() || desktopFileTreeOpen(),
-                    "size-0 shrink-0 overflow-hidden": !(desktopV2ReviewOpen() || desktopFileTreeOpen()),
-                  }}
-                >
+              <Show when={isDesktop() && (desktopV2ReviewOpen() || desktopFileTreeOpen())}>
+                <div class="min-h-0 flex-1">
                   <SessionSidePanel
                     canReview={canReview}
                     diffs={reviewDiffs}