diff --git a/packages/app/e2e/regression/mobile-sidebar-session-selection.spec.ts b/packages/app/e2e/regression/mobile-sidebar-session-selection.spec.ts
new file mode 100644
index 000000000000..9d67bf04fd78
--- /dev/null
+++ b/packages/app/e2e/regression/mobile-sidebar-session-selection.spec.ts
@@ -0,0 +1,46 @@
+import { base64Encode } from "@opencode-ai/core/util/encode"
+import { expect, test } from "@playwright/test"
+import { fixture, pageMessages } from "../smoke/session-timeline.fixture"
+import { mockOpenCodeServer } from "../utils/mock-server"
+import { expectSessionTitle } from "../utils/waits"
+
+const MOBILE_VIEWPORT_WIDTH = 390
+const SIDEBAR_AUTO_DISMISS_THRESHOLD = 250
+
+test.use({ viewport: { width: MOBILE_VIEWPORT_WIDTH, height: 800 } })
+
+test("dismisses full-width mobile sidebar after selecting a session", async ({ page }) => {
+  await mockOpenCodeServer(page, {
+    sessions: fixture.sessions,
+    provider: fixture.provider,
+    directory: fixture.directory,
+    project: fixture.project,
+    pageMessages,
+  })
+
+  await page.addInitScript((directory) => {
+    localStorage.setItem(
+      "opencode.global.dat:server",
+      JSON.stringify({
+        projects: { local: [{ worktree: directory, expanded: true }] },
+        lastProject: { local: directory },
+      }),
+    )
+  }, fixture.directory)
+
+  await page.goto(`/${base64Encode(fixture.directory)}/session/${fixture.sourceID}`)
+  await expectSessionTitle(page, fixture.expected.sourceTitle)
+
+  const toggle = page.getByRole("button", { name: "Toggle menu" })
+  await toggle.click()
+  await expect(toggle).toHaveAttribute("aria-expanded", "true")
+
+  const sidebar = page.locator('[data-component="sidebar-nav-mobile"]')
+  await expect
+    .poll(() => sidebar.evaluate((element) => element.getBoundingClientRect().width))
+    .toBeGreaterThanOrEqual(MOBILE_VIEWPORT_WIDTH - SIDEBAR_AUTO_DISMISS_THRESHOLD)
+
+  await sidebar.getByRole("link", { name: fixture.expected.targetTitle }).click()
+  await expectSessionTitle(page, fixture.expected.targetTitle)
+  await expect(toggle).toHaveAttribute("aria-expanded", "false")
+})
diff --git a/packages/app/src/pages/layout/sidebar-items.tsx b/packages/app/src/pages/layout/sidebar-items.tsx
index 776b81ae5a83..9cc08b2919c2 100644
--- a/packages/app/src/pages/layout/sidebar-items.tsx
+++ b/packages/app/src/pages/layout/sidebar-items.tsx
@@ -104,6 +104,7 @@ const SessionRow = (props: {
   warmPress: () => void
   warmFocus: () => void
 }): JSX.Element => {
+  const layout = useLayout()
   const title = () => sessionTitle(props.session.title)
 
   return (
@@ -112,7 +113,12 @@ const SessionRow = (props: {
       class={`flex items-center gap-2 min-w-0 w-full text-left focus:outline-none ${props.dense ? "py-0.5" : "py-1"}`}
       onPointerDown={props.warmPress}
       onFocus={props.warmFocus}
-      onClick={() => {
+      onClick={(event) => {
+        const sidebar = event.currentTarget.closest<HTMLElement>("[data-component='sidebar-nav-mobile']")
+        const sidebarAutoDismissThreshold = 250
+        if (sidebar && sidebar.getBoundingClientRect().width >= window.innerWidth - sidebarAutoDismissThreshold) {
+          layout.mobileSidebar.hide()
+        }
         if (props.sidebarOpened()) return
         props.clearHoverProjectSoon()
       }}