diff --git a/packages/gui-plugins/src/file/browser.tsx b/packages/gui-plugins/src/file/browser.tsx
index 6616b26e854e..8fd3e2b99d02 100644
--- a/packages/gui-plugins/src/file/browser.tsx
+++ b/packages/gui-plugins/src/file/browser.tsx
@@ -29,6 +29,7 @@ import {
 } from "@opencode/plugin/gui"
 import { current, useShared } from "./context"
 import SessionFileList, { applyFileListKeyDown } from "./list"
+import OpenInAppButton, { useOpenInApp } from "./open-in-app"
 import { fileTabPath, isFileTab } from "./path"
 import PierreFileTree from "./pierre-tree"
 import {
@@ -71,6 +72,19 @@ export function SessionFileBrowserTab(props: {
   const sidebarOpened = () => props.placeholder || props.state.opened()
   const query = createMemo(() => filter().trim())
 
+  const openIn = ctx.desktop
+    ? useOpenInApp({
+        get session() {
+          return props.session
+        },
+        path: () => file.root,
+      })
+    : undefined
+
+  // A file tab's header ends with "Open in": the tree's header while the tree is open, else the preview's.
+  const openInShown = () => !props.mobile && !props.placeholder && !!file.root && !!openIn?.canOpen()
+  const openInButton = () => <OpenInAppButton session={props.session} screen={props.screen} />
+
   // The filter's search. It asks the server directly: the screen's search reads a failure as no results.
   const [searchState, setSearchState] = createSignal<FileSearchState>(INITIAL_FILE_SEARCH_STATE)
   const searches = new Map<number, { controller: AbortController; timer: ReturnType<typeof setTimeout> }>()
@@ -226,6 +240,7 @@ export function SessionFileBrowserTab(props: {
     <SessionFilePanelV2
       toolbar={!props.mobile && !props.placeholder && !sidebarOpened()}
       toolbarStart={<span class="truncate font-[530]">{title()}</span>}
+      toolbarEnd={openInShown() ? openInButton() : undefined}
       sidebarCollapsed={!sidebarOpened()}
       sidebarToggleGap={10}
       sidebarToggle={
@@ -242,6 +257,7 @@ export function SessionFileBrowserTab(props: {
           open={sidebarOpened()}
           transition={props.state.transition()}
           title={<span class="truncate font-[530]">{title()}</span>}
+          actions={openInShown() ? openInButton() : undefined}
           filter={filter()}
           onFilterChange={setFilter}
           onFilterKeyDown={onFilterKeyDown}
diff --git a/packages/gui-plugins/src/file/renderer.tsx b/packages/gui-plugins/src/file/renderer.tsx
index 1ccb33fb6ca1..7d7837d7ad1a 100644
--- a/packages/gui-plugins/src/file/renderer.tsx
+++ b/packages/gui-plugins/src/file/renderer.tsx
@@ -9,7 +9,6 @@ import {
   Suspense,
   untrack,
   type ParentProps,
-  type Signal,
 } from "solid-js"
 import { createStore, produce, unwrap } from "solid-js/store"
 import { Icon } from "@opencode/ui/icon"
@@ -20,7 +19,6 @@ import {
   bindPlugin,
   LinkHandler,
   MenuItem,
-  Slot,
   Style,
   usePanel,
   type Files,
@@ -534,21 +532,6 @@ const setup: Plugin.Setup<typeof File> = (ctx) => {
     import("./open-in-app").then((module) => ({ default: module.OpenInAppMenuItem })),
   )
 
-  // How many "Open in" buttons each screen's panel headers show; the tab strip shows its own only while none do.
-  const headers = new WeakMap<SessionScreen, Signal<number>>()
-
-  const headerButtons = (screen: SessionScreen) => {
-    const existing = headers.get(screen)
-
-    if (existing) return existing
-
-    const created = createSignal(0)
-
-    headers.set(screen, created)
-
-    return created
-  }
-
   if (desktop) {
     onCleanup(
       onIdle(() => {
@@ -566,37 +549,18 @@ const setup: Plugin.Setup<typeof File> = (ctx) => {
         </FileProvider>
       ),
     })
-    ctx.add(Slot, {
-      at: "session.panel.end",
-      render: (input) => (
-        <Show when={headerButtons(input.screen)[0]() === 0}>
-          <FileProvider>
-            <Suspense>
-              <OpenInAppButton session={input.session} screen={input.screen} />
-            </Suspense>
-          </FileProvider>
-        </Show>
-      ),
-    })
   }
 
   ctx.provide(OpenInApp, {
-    Button: bindPlugin((props: OpenInAppProps) => {
-      const count = headerButtons(props.screen)
-
-      count[1]((value) => value + 1)
-      onCleanup(() => count[1]((value) => value - 1))
-
-      return (
-        <Show when={desktop}>
-          <FileProvider>
-            <Suspense>
-              <OpenInAppButton session={props.session} screen={props.screen} />
-            </Suspense>
-          </FileProvider>
-        </Show>
-      )
-    }),
+    Button: bindPlugin((props: OpenInAppProps) => (
+      <Show when={desktop}>
+        <FileProvider>
+          <Suspense>
+            <OpenInAppButton session={props.session} screen={props.screen} />
+          </Suspense>
+        </FileProvider>
+      </Show>
+    )),
   })
 
   // The review panel lists its changed files with the browser's tree; it renders under this plugin, on the
diff --git a/packages/gui-plugins/src/review/panel.tsx b/packages/gui-plugins/src/review/panel.tsx
index 1e512f54a310..6cbff3e0b4a6 100644
--- a/packages/gui-plugins/src/review/panel.tsx
+++ b/packages/gui-plugins/src/review/panel.tsx
@@ -149,6 +149,12 @@ function ReviewPanel(props: ReviewPanelProps) {
     return live.status === "active" ? live.value : undefined
   }
 
+  const openInButton = () => (
+    <Show when={openIn()}>
+      {(openIn) => <Dynamic component={openIn().Button} screen={props.screen} session={props.session} />}
+    </Show>
+  )
+
   const diffs = () => props.diffs
 
   const searching = createMemo(() => props.state.filter().trim().length > 0)
@@ -313,11 +319,7 @@ function ReviewPanel(props: ReviewPanelProps) {
       sidebarToggle={
         <SessionReviewV2SidebarToggle opened={props.state.sidebar.opened()} onToggle={props.state.sidebar.toggle} />
       }
-      toolbarAction={
-        <Show when={openIn()}>
-          {(openIn) => <Dynamic component={openIn().Button} screen={props.screen} session={props.session} />}
-        </Show>
-      }
+      toolbarAction={openInButton()}
       sidebar={
         // Always mounted: the sidebar header hosts the changes-mode dropdown,
         // which must stay reachable when the current mode has zero diffs.
@@ -334,6 +336,8 @@ function ReviewPanel(props: ReviewPanelProps) {
           kinds={treeKinds()}
           folderLabels={props.folderLabels}
           activeDiff={activeDiff()}
+          // Without diffs, the preview has no header while the tree is open.
+          actions={diffs().length === 0 ? openInButton() : undefined}
         />
       }
       activeFile={activeDiff()}
@@ -388,6 +392,7 @@ function ReviewPanelSidebar(props: {
   kinds: ReturnType<typeof reviewDiffKinds>
   folderLabels?: ReadonlyMap<string, string>
   activeDiff: string | undefined
+  actions?: JSX.Element
 }) {
   const ctx = usePlugin<typeof Review>()
 
@@ -426,6 +431,7 @@ function ReviewPanelSidebar(props: {
       transition={props.state.sidebar.transition()}
       title={props.title}
       stats={<DiffChanges changes={props.diffs} />}
+      actions={props.actions}
       filter={props.state.filter()}
       onFilterChange={props.state.setFilter}
       onFilterKeyDown={onFilterKeyDown}
diff --git a/packages/plugin/src/gui/file.ts b/packages/plugin/src/gui/file.ts
index 8497f1d1f480..aac5247c4729 100644
--- a/packages/plugin/src/gui/file.ts
+++ b/packages/plugin/src/gui/file.ts
@@ -77,10 +77,10 @@ export interface OpenInAppProps {
   readonly session: MountedSession
 }
 
-/** The desktop "Open in" button, for a panel header that shows it in place of the tab strip's. */
+/** The desktop "Open in" button, for a panel header such as the review's. */
 export interface OpenInApp {
   /**
-   * Renders nothing on the web or for a remote server. While it is mounted, the tab strip leaves out its own.
+   * Renders nothing on the web or for a remote server.
    *
    * @param props - The workspace to open.
    * @returns The button.
diff --git a/packages/session-ui/src/v2/components/session-review-v2.tsx b/packages/session-ui/src/v2/components/session-review-v2.tsx
index c6879d438ae2..274ff46a8716 100644
--- a/packages/session-ui/src/v2/components/session-review-v2.tsx
+++ b/packages/session-ui/src/v2/components/session-review-v2.tsx
@@ -45,6 +45,8 @@ export type SessionReviewV2SidebarProps = {
   transition: boolean
   title?: JSX.Element
   stats?: JSX.Element
+  /** Controls at the header's end, after the stats. */
+  actions?: JSX.Element
   filter: string
   onFilterChange: (value: string) => void
   onFilterKeyDown?: JSX.EventHandlerUnion<HTMLInputElement, KeyboardEvent>
@@ -80,6 +82,7 @@ export function SessionReviewV2Sidebar(props: SessionReviewV2SidebarProps) {
           <div data-slot="session-review-v2-sidebar-header">
             <div data-slot="session-review-v2-sidebar-title">{props.title}</div>
             {props.stats}
+            {props.actions}
           </div>
           <div data-slot="session-review-v2-sidebar-filter">
             <TextInput