From ea9ffbaea5c475225c23f1dd497498b09014e19d Mon Sep 17 00:00:00 2001
From: hmrserver <20267810+hmrserver@users.noreply.github.com>
Date: Thu, 9 Jul 2026 13:03:59 -0700
Subject: [PATCH] Add right-sidebar edge peek (extracted from #7423)

Arc-style hover peek: when the right sidebar is closed, hovering the
window's right edge reveals it as a floating overlay without reflowing
the editor; moving away dismisses it, and an explicit open pins it.
Extracted unchanged from PR #7423 so it can be reviewed on its own.

Co-authored-by: Orca <help@stably.ai>
---
 src/renderer/src/App.tsx                      |   7 +-
 .../src/components/right-sidebar/index.tsx    |  42 +++-
 .../right-sidebar-edge-peek.test.tsx          | 225 ++++++++++++++++++
 .../right-sidebar/right-sidebar-edge-peek.tsx | 155 ++++++++++++
 src/renderer/src/store/slices/editor.ts       |  13 +-
 5 files changed, 429 insertions(+), 13 deletions(-)
 create mode 100644 src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.test.tsx
 create mode 100644 src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.tsx

diff --git a/src/renderer/src/App.tsx b/src/renderer/src/App.tsx
index eb34e42b62e..6c2522288d0 100644
--- a/src/renderer/src/App.tsx
+++ b/src/renderer/src/App.tsx
@@ -55,6 +55,7 @@ import {
   useSystemPrefersDark
 } from './components/terminal-pane/use-system-prefers-dark'
 import RightSidebar from './components/right-sidebar'
+import { RightSidebarEdgePeekZone } from './components/right-sidebar/right-sidebar-edge-peek'
 import { StarNagCard } from './components/StarNagCard'
 import { StarNagAgentValueMomentObserver } from './components/star-nag/StarNagAgentValueMomentObserver'
 import { StarNagToastHost } from './components/star-nag/StarNagToastHost'
@@ -2211,7 +2212,10 @@ function App(): React.JSX.Element {
                 'The app is still running. Retry the shell or use the menu to report the crash details.'
               )}
             >
-              <div className="flex flex-row flex-1 min-h-0 overflow-hidden">
+              {/* Why: relative anchors the right-sidebar edge-peek overlay to
+              this row, so a peek spans the same height as the docked sidebar
+              and ends above the status bar. */}
+              <div className="relative flex flex-row flex-1 min-h-0 overflow-hidden">
                 {/* Why: the non-workspace titlebar lives inside this left+center
               wrapper so it does not span over the right-sidebar column —
               when the right sidebar is open, its own header anchors at the
@@ -2428,6 +2432,7 @@ function App(): React.JSX.Element {
               Its heavy panels disconnect while closed so workspace wake stays
               responsive. Unmount on the tasks view since that surface is
               intentionally distraction-free. */}
+                {showRightSidebarControls ? <RightSidebarEdgePeekZone /> : null}
                 {showRightSidebarControls ? (
                   <RecoverableRenderErrorBoundary
                     boundaryId="right-sidebar"
diff --git a/src/renderer/src/components/right-sidebar/index.tsx b/src/renderer/src/components/right-sidebar/index.tsx
index cc0eb6a36b8..f078818b78e 100644
--- a/src/renderer/src/components/right-sidebar/index.tsx
+++ b/src/renderer/src/components/right-sidebar/index.tsx
@@ -39,6 +39,7 @@ import {
 } from './right-sidebar-width'
 import { translate } from '@/i18n/i18n'
 import { RightSidebarPanelContent } from './right-sidebar-panel-content'
+import { useRightSidebarEdgePeekDismiss } from './right-sidebar-edge-peek'
 import { useMeasuredWidth } from './right-sidebar-measured-width'
 import { normalizeRightSidebarRoute } from '@/store/right-sidebar-route'
 import { AgentSessionHistoryIcon } from './agent-session-history-icon'
@@ -62,6 +63,8 @@ function RightSidebarInner(): React.JSX.Element {
   const checksShortcut = useShortcutLabel('sidebar.checks.toggle')
   const portsShortcut = useShortcutLabel('sidebar.ports.toggle')
   const rightSidebarOpen = useAppStore((s) => s.rightSidebarOpen)
+  const rightSidebarPeek = useAppStore((s) => s.rightSidebarPeek)
+  const setRightSidebarPeek = useAppStore((s) => s.setRightSidebarPeek)
   const rightSidebarWidth = useAppStore((s) => s.rightSidebarWidth)
   const setRightSidebarWidth = useAppStore((s) => s.setRightSidebarWidth)
   const rightSidebarTab = useAppStore((s) => s.rightSidebarTab)
@@ -69,11 +72,17 @@ function RightSidebarInner(): React.JSX.Element {
   const setRightSidebarTab = useAppStore((s) => s.setRightSidebarTab)
   const showRightSidebarFiles = useAppStore((s) => s.showRightSidebarFiles)
   const toggleRightSidebar = useAppStore((s) => s.toggleRightSidebar)
-  const checksStatus = useAppStore((s) => (s.rightSidebarOpen ? getActiveChecksStatus(s) : null))
+  // An edge-hover peek shows the same content as a pinned-open sidebar; only
+  // the positioning differs (floating overlay vs in-flow panel).
+  const isPeeking = rightSidebarPeek && !rightSidebarOpen
+  const sidebarVisible = rightSidebarOpen || isPeeking
+  const checksStatus = useAppStore((s) =>
+    s.rightSidebarOpen || s.rightSidebarPeek ? getActiveChecksStatus(s) : null
+  )
   const activityBarPosition = useAppStore((s) => s.activityBarPosition)
   const setActivityBarPosition = useAppStore((s) => s.setActivityBarPosition)
   const [topActivityStripWidth, setTopActivityStripWidth] = useState<number | null>(null)
-  const activeWorktreeId = useAppStore((s) => (rightSidebarOpen ? s.activeWorktreeId : null))
+  const activeWorktreeId = useAppStore((s) => (sidebarVisible ? s.activeWorktreeId : null))
   // Why: source control and checks are meaningless for non-git folders.
   // Hide those tabs so the activity bar only shows relevant actions.
   const activeWorktree = useAppStore((s) =>
@@ -204,8 +213,8 @@ function RightSidebarInner(): React.JSX.Element {
     windowWidth,
     activityBarSideWidth
   )
-  const { containerRef, onResizeStart } = useSidebarResize<HTMLDivElement>({
-    isOpen: rightSidebarOpen,
+  const { containerRef, isResizing, onResizeStart } = useSidebarResize<HTMLDivElement>({
+    isOpen: sidebarVisible,
     width: renderedRightSidebarWidth,
     minWidth: RIGHT_SIDEBAR_MIN_WIDTH,
     maxWidth,
@@ -213,9 +222,15 @@ function RightSidebarInner(): React.JSX.Element {
     renderedExtraWidth: activityBarSideWidth,
     setWidth: setRightSidebarWidth
   })
+  useRightSidebarEdgePeekDismiss({
+    isPeeking,
+    isResizing,
+    setPeek: setRightSidebarPeek,
+    overlayRef: containerRef
+  })
   const topActivityStripRef = useMeasuredWidth(setTopActivityStripWidth)
 
-  const panelContent = rightSidebarOpen ? (
+  const panelContent = sidebarVisible ? (
     <div className="flex flex-col flex-1 min-h-0 overflow-hidden scrollbar-sleek-parent">
       {/* Why: sidebar panels no longer use key={activeWorktreeId} because
           the full unmount/remount cycle on every worktree switch triggered
@@ -228,7 +243,7 @@ function RightSidebarInner(): React.JSX.Element {
           property) rather than in a bottom-docked dashboard panel that
           competed with file Explorer/Search for vertical space. The right
           sidebar is back to tab-only content. */}
-      <RightSidebarPanelContent effectiveTab={effectiveTab} rightSidebarOpen={rightSidebarOpen} />
+      <RightSidebarPanelContent effectiveTab={effectiveTab} rightSidebarOpen={sidebarVisible} />
     </div>
   ) : null
 
@@ -248,7 +263,9 @@ function RightSidebarInner(): React.JSX.Element {
     />
   ))
 
-  const closeButton = rightSidebarOpen ? (
+  // During a peek the same button pins the sidebar open (toggle clears the
+  // peek flag alongside flipping open).
+  const closeButton = sidebarVisible ? (
     <Tooltip>
       <TooltipTrigger asChild>
         <button
@@ -277,20 +294,25 @@ function RightSidebarInner(): React.JSX.Element {
     <div
       ref={containerRef}
       className={cn(
-        'relative flex-shrink-0 flex flex-row',
+        'flex-shrink-0 flex flex-row',
         // Why: overflow-visible is needed when open so the resize handle
         // on the left edge remains interactive.  When closed (width 0),
         // switch to overflow-hidden so the activity bar icons and panel
         // content don't leak past the 0-width boundary (the component
         // stays mounted for performance — see App.tsx).
-        rightSidebarOpen ? 'overflow-visible' : 'overflow-hidden'
+        sidebarVisible ? 'overflow-visible' : 'overflow-hidden',
+        // A peek floats over the content row (no reflow) with the
+        // styleguide's floating-surface shadow; pinned-open stays in flow.
+        isPeeking
+          ? 'absolute inset-y-0 right-0 z-30 shadow-[0_10px_24px_rgba(0,0,0,0.18)] animate-in slide-in-from-right duration-200 motion-reduce:animate-none'
+          : 'relative'
       )}
     >
       {/* Panel content area */}
       <div
         className="flex flex-col flex-1 min-w-0 bg-sidebar overflow-hidden"
         style={{
-          borderLeft: rightSidebarOpen ? '1px solid var(--sidebar-border)' : 'none'
+          borderLeft: sidebarVisible ? '1px solid var(--sidebar-border)' : 'none'
         }}
       >
         {activityBarPosition === 'top' ? (
diff --git a/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.test.tsx b/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.test.tsx
new file mode 100644
index 00000000000..7f39607c9bc
--- /dev/null
+++ b/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.test.tsx
@@ -0,0 +1,225 @@
+// @vitest-environment happy-dom
+
+import { act, fireEvent, render, renderHook } from '@testing-library/react'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import { useAppStore } from '@/store'
+import {
+  PEEK_CLOSE_DELAY_MS,
+  PEEK_OPEN_DELAY_MS,
+  RightSidebarEdgePeekZone,
+  useRightSidebarEdgePeekDismiss
+} from './right-sidebar-edge-peek'
+
+const initialAppState = useAppStore.getInitialState()
+
+beforeEach(() => {
+  vi.useFakeTimers()
+})
+
+afterEach(() => {
+  vi.useRealTimers()
+  useAppStore.setState(initialAppState, true)
+})
+
+function makeOverlayRef(left: number): React.RefObject<HTMLElement | null> {
+  return makeMovingOverlayRef(() => left)
+}
+
+// Overlay whose measured left edge changes between reads (e.g. the slide-in
+// entrance transform still translating the panel when first measured).
+function makeMovingOverlayRef(readLeft: () => number): React.RefObject<HTMLElement | null> {
+  return {
+    current: { getBoundingClientRect: () => ({ left: readLeft() }) } as unknown as HTMLElement
+  }
+}
+
+const RIGHT_EDGE_X = window.innerWidth - 1
+const BELOW_TITLEBAR_Y = 100
+
+function moveMouse(clientX: number, clientY: number): void {
+  act(() => {
+    fireEvent.mouseMove(window, { clientX, clientY })
+  })
+}
+
+describe('RightSidebarEdgePeekZone', () => {
+  it('renders nothing (no DOM strip that could swallow edge clicks)', () => {
+    const { container } = render(<RightSidebarEdgePeekZone />)
+    expect(container.firstElementChild).toBeNull()
+  })
+
+  it('arms the peek after the pointer hovers the right edge for the open delay', () => {
+    render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, BELOW_TITLEBAR_Y)
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+    expect(useAppStore.getState().rightSidebarPeek).toBe(true)
+  })
+
+  it('cancels an armed peek when the pointer leaves the edge before the delay', () => {
+    render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, BELOW_TITLEBAR_Y)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS - 1)
+    moveMouse(RIGHT_EDGE_X - 200, BELOW_TITLEBAR_Y)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+  })
+
+  it('ignores the top titlebar zone so window controls stay clickable', () => {
+    render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, 10)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+  })
+
+  it('does not arm while the sidebar is already open', () => {
+    useAppStore.setState({ rightSidebarOpen: true })
+    render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, BELOW_TITLEBAR_Y)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+  })
+
+  it('clears an active peek when the zone unmounts on a view change', () => {
+    const { unmount } = render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, BELOW_TITLEBAR_Y)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+    expect(useAppStore.getState().rightSidebarPeek).toBe(true)
+
+    unmount()
+
+    // A surviving flag would render a ghost peek when the user returns to a
+    // sidebar-capable view.
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+  })
+
+  it('clears an armed timer if the sidebar opens before it fires', () => {
+    const { rerender } = render(<RightSidebarEdgePeekZone />)
+
+    moveMouse(RIGHT_EDGE_X, BELOW_TITLEBAR_Y)
+    act(() => {
+      useAppStore.setState({ rightSidebarOpen: true })
+    })
+    rerender(<RightSidebarEdgePeekZone />)
+    vi.advanceTimersByTime(PEEK_OPEN_DELAY_MS)
+
+    // The pending open timer must not flip peek on after the sidebar opened.
+    expect(useAppStore.getState().rightSidebarPeek).toBe(false)
+  })
+})
+
+describe('useRightSidebarEdgePeekDismiss', () => {
+  it('dismisses after the pointer stays left of the overlay for the close delay', () => {
+    const setPeek = vi.fn()
+    renderHook(() =>
+      useRightSidebarEdgePeekDismiss({
+        isPeeking: true,
+        isResizing: false,
+        setPeek,
+        overlayRef: makeOverlayRef(1000)
+      })
+    )
+
+    fireEvent.mouseMove(window, { clientX: 400 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+
+    expect(setPeek).toHaveBeenCalledWith(false)
+  })
+
+  it('keeps the peek when the pointer returns to the overlay before the delay', () => {
+    const setPeek = vi.fn()
+    renderHook(() =>
+      useRightSidebarEdgePeekDismiss({
+        isPeeking: true,
+        isResizing: false,
+        setPeek,
+        overlayRef: makeOverlayRef(1000)
+      })
+    )
+
+    fireEvent.mouseMove(window, { clientX: 400 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS - 1)
+    fireEvent.mouseMove(window, { clientX: 1100 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+
+    expect(setPeek).not.toHaveBeenCalled()
+  })
+
+  it('does not dismiss when the boundary was measured mid entrance animation', () => {
+    const setPeek = vi.fn()
+    // First read happens during the slide-in: the overlay still sits near the
+    // window's right edge. By the time the close timer re-measures, the
+    // animation has settled at its real position.
+    let overlayLeft = 1590
+    renderHook(() =>
+      useRightSidebarEdgePeekDismiss({
+        isPeeking: true,
+        isResizing: false,
+        setPeek,
+        overlayRef: makeMovingOverlayRef(() => overlayLeft)
+      })
+    )
+
+    // The pointer moves into the settled overlay area (left of the stale
+    // mid-animation boundary), which schedules a close against stale geometry.
+    fireEvent.mouseMove(window, { clientX: 1200 })
+    overlayLeft = 1000
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+
+    // The re-measure inside the close timer sees the settled boundary and
+    // keeps the peek open.
+    expect(setPeek).not.toHaveBeenCalled()
+
+    // The refreshed cache now classifies the same position as inside.
+    fireEvent.mouseMove(window, { clientX: 1200 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+    expect(setPeek).not.toHaveBeenCalled()
+
+    // A genuine exit still dismisses.
+    fireEvent.mouseMove(window, { clientX: 400 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+    expect(setPeek).toHaveBeenCalledWith(false)
+  })
+
+  it('does not dismiss while a resize drag travels past the overlay edge', () => {
+    const setPeek = vi.fn()
+    renderHook(() =>
+      useRightSidebarEdgePeekDismiss({
+        isPeeking: true,
+        isResizing: true,
+        setPeek,
+        overlayRef: makeOverlayRef(1000)
+      })
+    )
+
+    fireEvent.mouseMove(window, { clientX: 100 })
+    vi.advanceTimersByTime(PEEK_CLOSE_DELAY_MS)
+
+    expect(setPeek).not.toHaveBeenCalled()
+  })
+
+  it('dismisses immediately when the window loses focus', () => {
+    const setPeek = vi.fn()
+    renderHook(() =>
+      useRightSidebarEdgePeekDismiss({
+        isPeeking: true,
+        isResizing: false,
+        setPeek,
+        overlayRef: makeOverlayRef(1000)
+      })
+    )
+
+    fireEvent.blur(window)
+
+    expect(setPeek).toHaveBeenCalledWith(false)
+  })
+})
diff --git a/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.tsx b/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.tsx
new file mode 100644
index 00000000000..90563ad993c
--- /dev/null
+++ b/src/renderer/src/components/right-sidebar/right-sidebar-edge-peek.tsx
@@ -0,0 +1,155 @@
+import React, { useEffect, useRef } from 'react'
+import { useAppStore } from '@/store'
+
+// Arc-style edge peek: hovering the window's right edge while the sidebar is
+// closed reveals it as a floating overlay instead of reflowing the editor.
+// The enter delay keeps edge scrollbar grabs from flashing the sidebar open.
+export const PEEK_OPEN_DELAY_MS = 250
+export const PEEK_CLOSE_DELAY_MS = 300
+// The rightmost band that arms the peek, and the top zone it excludes.
+const PEEK_EDGE_TRIGGER_PX = 6
+const PEEK_TITLEBAR_ZONE_PX = 36
+
+/**
+ * Arms the edge peek while the sidebar is fully hidden. Detection is
+ * geometry-based (a window mousemove comparing clientX against the right edge)
+ * rather than an invisible DOM strip: a strip would swallow every mousedown in
+ * the rightmost pixels, blocking scrollbar drags and clicks flush against the
+ * window edge. Renders nothing.
+ */
+export function RightSidebarEdgePeekZone(): React.JSX.Element | null {
+  const rightSidebarOpen = useAppStore((s) => s.rightSidebarOpen)
+  const rightSidebarPeek = useAppStore((s) => s.rightSidebarPeek)
+  const setRightSidebarPeek = useAppStore((s) => s.setRightSidebarPeek)
+
+  useEffect(() => {
+    // Why: the zone unmounts when the active view loses sidebar controls; a
+    // peek flag surviving that would render a ghost peek (no hover behind it)
+    // when the user returns to a sidebar-capable view.
+    return () => setRightSidebarPeek(false)
+  }, [setRightSidebarPeek])
+
+  useEffect(() => {
+    // The revealed overlay covers the edge, so arming is only needed while the
+    // sidebar is fully hidden. Skipping the listener here also guarantees an
+    // armed timer can't fire after the sidebar opens (the cleanup clears it).
+    if (rightSidebarOpen || rightSidebarPeek) {
+      return
+    }
+    let openTimer: number | null = null
+    const clearOpenTimer = (): void => {
+      if (openTimer !== null) {
+        window.clearTimeout(openTimer)
+        openTimer = null
+      }
+    }
+    const onMouseMove = (event: MouseEvent): void => {
+      // Why: exclude the top 36px titlebar row so the peek never arms over
+      // window controls (Windows/Linux custom chrome).
+      const inEdgeBand =
+        event.clientY >= PEEK_TITLEBAR_ZONE_PX &&
+        event.clientX >= window.innerWidth - PEEK_EDGE_TRIGGER_PX
+      if (!inEdgeBand) {
+        clearOpenTimer()
+        return
+      }
+      if (openTimer === null) {
+        openTimer = window.setTimeout(() => {
+          openTimer = null
+          setRightSidebarPeek(true)
+        }, PEEK_OPEN_DELAY_MS)
+      }
+    }
+    window.addEventListener('mousemove', onMouseMove)
+    return () => {
+      clearOpenTimer()
+      window.removeEventListener('mousemove', onMouseMove)
+    }
+  }, [rightSidebarOpen, rightSidebarPeek, setRightSidebarPeek])
+
+  return null
+}
+
+/**
+ * Dismisses an active peek once the pointer moves left of the revealed
+ * overlay. Dismissal is geometry-based (window mousemove) rather than
+ * mouseleave-based: tooltips and menus portal outside the overlay element,
+ * and a mouseleave dismiss would close the peek under an open popover.
+ */
+export function useRightSidebarEdgePeekDismiss(args: {
+  isPeeking: boolean
+  isResizing: boolean
+  setPeek: (peek: boolean) => void
+  overlayRef: React.RefObject<HTMLElement | null>
+}): void {
+  const { isPeeking, isResizing, setPeek, overlayRef } = args
+  // Why: the dismiss watcher reads resize state inside window listeners; a ref
+  // avoids re-subscribing them on every drag frame.
+  const isResizingRef = useRef(isResizing)
+  isResizingRef.current = isResizing
+
+  useEffect(() => {
+    if (!isPeeking) {
+      return
+    }
+    let closeTimer: number | null = null
+    let lastClientX: number | null = null
+    // Why: measuring the overlay on every mousemove forces layout. Cache its
+    // left edge and invalidate only when it can move (a resize drag or a window
+    // resize), so the common per-frame move reads no geometry.
+    let cachedOverlayLeft: number | null = null
+    const invalidateOverlayLeft = (): void => {
+      cachedOverlayLeft = null
+    }
+    const cancelClose = (): void => {
+      if (closeTimer !== null) {
+        window.clearTimeout(closeTimer)
+        closeTimer = null
+      }
+    }
+    const scheduleClose = (): void => {
+      if (closeTimer === null) {
+        closeTimer = window.setTimeout(() => {
+          closeTimer = null
+          // Why: the cached boundary may have been measured mid slide-in (the
+          // entrance transform puts the rect near the window edge). Re-measure
+          // and re-check here so a stale cache self-heals instead of
+          // dismissing the peek under the cursor.
+          const overlayLeft = overlayRef.current?.getBoundingClientRect().left ?? null
+          cachedOverlayLeft = overlayLeft
+          if (overlayLeft !== null && lastClientX !== null && lastClientX >= overlayLeft) {
+            return
+          }
+          setPeek(false)
+        }, PEEK_CLOSE_DELAY_MS)
+      }
+    }
+    const onMouseMove = (event: MouseEvent): void => {
+      lastClientX = event.clientX
+      // A resize drag legitimately travels left of the overlay edge.
+      if (isResizingRef.current) {
+        invalidateOverlayLeft()
+        cancelClose()
+        return
+      }
+      if (cachedOverlayLeft === null) {
+        cachedOverlayLeft = overlayRef.current?.getBoundingClientRect().left ?? null
+      }
+      if (cachedOverlayLeft === null || event.clientX >= cachedOverlayLeft) {
+        cancelClose()
+      } else {
+        scheduleClose()
+      }
+    }
+    const onWindowBlur = (): void => setPeek(false)
+    window.addEventListener('mousemove', onMouseMove)
+    window.addEventListener('blur', onWindowBlur)
+    window.addEventListener('resize', invalidateOverlayLeft)
+    return () => {
+      cancelClose()
+      window.removeEventListener('mousemove', onMouseMove)
+      window.removeEventListener('blur', onWindowBlur)
+      window.removeEventListener('resize', invalidateOverlayLeft)
+    }
+  }, [isPeeking, overlayRef, setPeek])
+}
diff --git a/src/renderer/src/store/slices/editor.ts b/src/renderer/src/store/slices/editor.ts
index 2a63053f3e1..9b81319e43c 100644
--- a/src/renderer/src/store/slices/editor.ts
+++ b/src/renderer/src/store/slices/editor.ts
@@ -430,6 +430,9 @@ export type EditorSlice = {
 
   // Right sidebar
   rightSidebarOpen: boolean
+  // Transient edge-hover reveal (Arc-style). Never persisted: a peek is a
+  // pointer gesture, not a saved layout choice like rightSidebarOpen.
+  rightSidebarPeek: boolean
   rightSidebarWidth: number
   rightSidebarTab: ActiveRightSidebarTab
   rightSidebarExplorerView: RightSidebarExplorerView
@@ -439,6 +442,7 @@ export type EditorSlice = {
   activityBarPosition: ActivityBarPosition
   toggleRightSidebar: () => void
   setRightSidebarOpen: (open: boolean) => void
+  setRightSidebarPeek: (peek: boolean) => void
   setRightSidebarWidth: (width: number) => void
   setRightSidebarTab: (tab: ActiveRightSidebarTab) => void
   setRightSidebarExplorerView: (view: RightSidebarExplorerView) => void
@@ -1439,6 +1443,7 @@ export const createEditorSlice: StateCreator<AppState, [], [], EditorSlice> = (s
 
   // Right sidebar
   rightSidebarOpen: false,
+  rightSidebarPeek: false,
   rightSidebarWidth: 280,
   rightSidebarTab: 'explorer',
   rightSidebarExplorerView: 'files',
@@ -1446,8 +1451,12 @@ export const createEditorSlice: StateCreator<AppState, [], [], EditorSlice> = (s
   rightSidebarTabByWorktree: {},
   rightSidebarExplorerViewByWorktree: {},
   activityBarPosition: 'top',
-  toggleRightSidebar: () => set((s) => ({ rightSidebarOpen: !s.rightSidebarOpen })),
-  setRightSidebarOpen: (open) => set({ rightSidebarOpen: open }),
+  // Why: an explicit open/close supersedes a hover peek — clearing the flag
+  // here keeps "toggle while peeking" meaning "pin it open".
+  toggleRightSidebar: () =>
+    set((s) => ({ rightSidebarOpen: !s.rightSidebarOpen, rightSidebarPeek: false })),
+  setRightSidebarOpen: (open) => set({ rightSidebarOpen: open, rightSidebarPeek: false }),
+  setRightSidebarPeek: (peek) => set({ rightSidebarPeek: peek }),
   setRightSidebarWidth: (width) => set({ rightSidebarWidth: width }),
   setRightSidebarTab: (tab) =>
     set((s) => ({