diff --git a/app.go b/app.go
index 5d10582..55e3f08 100644
--- a/app.go
+++ b/app.go
@@ -4,6 +4,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"fmt"
 	"image"
 	"log/slog"
@@ -43,11 +44,11 @@ type App struct {
 
 	// capturing prevents re-entrant capture sessions when the user mashes
 	// the hotkey while a previous one is still running. It stays true for
-// the entire lifecycle of one capture: from overlay start until the
+	// the entire lifecycle of one capture: from overlay start until the
 	// overlay is either confirmed (ConfirmRegion) or discarded (CancelRegion).
 	capturing atomic.Bool
 
-// pendingMu guards `pending`. We keep this separate from `mu` so that
+	// pendingMu guards `pending`. We keep this separate from `mu` so that
 	// frontend-triggered RPC handlers (which may run concurrently with the
 	// capture goroutine) can take it cheaply.
 	pendingMu sync.Mutex
@@ -80,6 +81,13 @@ type RegionRect struct {
 	H int `json:"h"`
 }
 
+// CaptureResult is returned by the overlay with the final selection and any
+// annotations drawn inside the selected area.
+type CaptureResult struct {
+	Rect        RegionRect               `json:"rect"`
+	Annotations []application.Annotation `json:"annotations"`
+}
+
 // NewApp creates a new App with collaborators already initialised.
 func NewApp() *App {
 	store, err := config.NewFileStore()
@@ -357,7 +365,7 @@ func (a *App) CaptureNow() {
 // Returning the error to the frontend lets the overlay decide whether to
 // keep showing the screenshot (e.g. for a retry) — currently it just
 // dismisses regardless and surfaces the error via the upload:failure toast.
-func (a *App) ConfirmRegion(rect RegionRect) error {
+func (a *App) ConfirmRegion(result CaptureResult) error {
 	a.pendingMu.Lock()
 	pc := a.pending
 	a.pending = nil
@@ -371,6 +379,7 @@ func (a *App) ConfirmRegion(rect RegionRect) error {
 		a.dismissOverlay()
 	}()
 
+	rect := result.Rect
 	captureRect := image.Rect(rect.X, rect.Y, rect.X+rect.W, rect.Y+rect.H)
 	a.dismissOverlay()
 	flushFrame()
@@ -380,6 +389,13 @@ func (a *App) ConfirmRegion(rect RegionRect) error {
 		wruntime.EventsEmit(a.ctx, "upload:failure", err.Error())
 		return err
 	}
+	if len(result.Annotations) > 0 {
+		cropped, err = application.ApplyAnnotations(cropped, result.Annotations, pc.Display.Scale)
+		if err != nil {
+			wruntime.EventsEmit(a.ctx, "upload:failure", err.Error())
+			return err
+		}
+	}
 	if err := a.runUploadPipeline(pc.Provider, cropped); err != nil {
 		return err
 	}
@@ -389,7 +405,7 @@ func (a *App) ConfirmRegion(rect RegionRect) error {
 // ConfirmNativeRegion mirrors ConfirmRegion for the macOS native overlay.
 // The native AppKit panel has already been closed by the time this method is
 // called, so we must not dismiss/restore the Wails overlay window here.
-func (a *App) ConfirmNativeRegion(rect RegionRect) error {
+func (a *App) ConfirmNativeRegion(result CaptureResult) error {
 	a.pendingMu.Lock()
 	pc := a.pending
 	a.pending = nil
@@ -403,6 +419,7 @@ func (a *App) ConfirmNativeRegion(rect RegionRect) error {
 		hideDockIcon()
 	}()
 
+	rect := result.Rect
 	captureRect := image.Rect(rect.X, rect.Y, rect.X+rect.W, rect.Y+rect.H)
 	flushFrame()
 	cropped, err := a.capturer.CaptureRegion(captureRect)
@@ -410,9 +427,28 @@ func (a *App) ConfirmNativeRegion(rect RegionRect) error {
 		wruntime.EventsEmit(a.ctx, "upload:failure", err.Error())
 		return err
 	}
+	if len(result.Annotations) > 0 {
+		cropped, err = application.ApplyAnnotations(cropped, result.Annotations, pc.Display.Scale)
+		if err != nil {
+			wruntime.EventsEmit(a.ctx, "upload:failure", err.Error())
+			return err
+		}
+	}
 	return a.runUploadPipeline(pc.Provider, cropped)
 }
 
+func parseNativeAnnotations(raw string) []application.Annotation {
+	if raw == "" {
+		return nil
+	}
+	var annotations []application.Annotation
+	if err := json.Unmarshal([]byte(raw), &annotations); err != nil {
+		slog.Warn("parse native annotations failed", "err", err)
+		return nil
+	}
+	return annotations
+}
+
 // CancelRegion is invoked when the user dismisses the overlay (Esc /
 // Cancel button / right-click). Frees the pending PNG, releases the
 // capture lock, and hides the overlay.
diff --git a/frontend/src/App.vue b/frontend/src/App.vue
index 648a0c7..10f2001 100644
--- a/frontend/src/App.vue
+++ b/frontend/src/App.vue
@@ -62,17 +62,24 @@ async function retryHotkey() {
 }
 
 async function onOverlayConfirm(rect: {
-  x: number
-  y: number
-  w: number
-  h: number
+  rect: {
+    x: number
+    y: number
+    w: number
+    h: number
+  }
+  annotations: Array<{
+    tool: string
+    color: string
+    points: Array<{ x: number; y: number }>
+  }>
 }) {
   // Optimistically swap back so the window does not visually lag the
   // Go-side hide. If upload fails, the toast surfaces the reason.
   mode.value = 'settings'
   overlayPayload.value = null
   try {
-    await ConfirmRegion(rect)
+    await ConfirmRegion(rect as any)
   } catch {
     /* Surfaced via upload:failure */
   }
diff --git a/frontend/src/views/CaptureOverlay.vue b/frontend/src/views/CaptureOverlay.vue
index 851544a..8e2d3ca 100644
--- a/frontend/src/views/CaptureOverlay.vue
+++ b/frontend/src/views/CaptureOverlay.vue
@@ -1,142 +1,322 @@
 <script setup lang="ts">
-/*
- * CaptureOverlay — Snipaste-style region picker.
- *
- * Three layers, painted in order:
- *   1. Dark mask + selection  : a single SVG that draws a 0.4 alpha
- *                               black rectangle over the whole screen
- *                               with the selection cut out via fill-rule
- *                               evenodd. The Wails window itself is
- *                               transparent, so the cut-out shows the live
- *                               desktop rather than a stale screenshot.
- *   2. Toolbar                : floats just outside the bottom-right of
- *                               the selection rectangle (Snipaste rule).
- *
- * Interaction model (kept minimal per user choice):
- *   • If no selection yet: mousedown drags out a new rectangle.
- *   • If selection exists: mousedown INSIDE moves it; OUTSIDE re-drags.
- *   • Esc / Cancel button → emit('cancel')
- *   • Enter / Upload button → emit('confirm', rect)
- */
 import { computed, onMounted, onUnmounted, ref } from 'vue'
 
 interface Props {
-  /** Logical (CSS) width of the primary display. */
   width: number
-  /** Logical (CSS) height of the primary display. */
   height: number
 }
 const props = defineProps<Props>()
 
-const emit = defineEmits<{
-  (e: 'confirm', rect: { x: number; y: number; w: number; h: number }): void
-  (e: 'cancel'): void
-}>()
-
-// Selection rect stored in CSS pixels. null = nothing selected yet.
 interface Rect {
   x: number
   y: number
   w: number
   h: number
 }
+
+type Tool = 'pen' | 'rect' | 'ellipse'
+interface Point {
+  x: number
+  y: number
+}
+interface Annotation {
+  tool: Tool
+  color: string
+  points: Point[]
+}
+
+const emit = defineEmits<{
+  (
+    e: 'confirm',
+    payload: { rect: Rect; annotations: Annotation[] }
+  ): void
+  (e: 'cancel'): void
+}>()
+
 const rect = ref<Rect | null>(null)
+const annotations = ref<Annotation[]>([])
+const draftAnnotation = ref<Annotation | null>(null)
+const activeTool = ref<Tool>('pen')
+const activeColor = ref('#ef4444')
+const paletteOpen = ref(false)
 
-// Drag state machine.
-type DragMode = 'idle' | 'creating' | 'moving'
+type ResizeHandle = 'n' | 's' | 'e' | 'w' | 'nw' | 'ne' | 'sw' | 'se'
+type DragMode = 'idle' | 'creating' | 'moving' | 'resizing' | 'annotating'
 const dragMode = ref<DragMode>('idle')
-// For 'creating': the anchor where mousedown started.
-// For 'moving' : the mouse offset relative to the rect's top-left.
+const resizeHandle = ref<ResizeHandle | null>(null)
 const dragAnchor = ref({ x: 0, y: 0 })
+const startRect = ref<Rect | null>(null)
+
+const colors = [
+  '#ef4444',
+  '#f97316',
+  '#facc15',
+  '#22c55e',
+  '#06b6d4',
+  '#3b82f6',
+  '#8b5cf6',
+  '#ec4899',
+  '#ffffff',
+  '#111827',
+]
 
-// SVG path for "the entire screen with the selection rect cut out".
-// We rely on fill-rule:evenodd to subtract the inner rectangle.
 const maskPath = computed(() => {
   const outer = `M0 0 H${props.width} V${props.height} H0 Z`
   if (!rect.value) return outer
   const r = rect.value
-  // Inner rect drawn in the OPPOSITE winding order so evenodd cuts it.
   const inner = `M${r.x} ${r.y} H${r.x + r.w} V${r.y + r.h} H${r.x} Z`
   return outer + ' ' + inner
 })
 
-// Toolbar placement: anchor to bottom-right of the selection, but shove
-// it to the inside top-right if the selection is too close to the screen
-// edge to keep the buttons visible.
-const TOOLBAR_W = 220
-const TOOLBAR_H = 40
-const GAP = 8
-const toolbarPos = computed(() => {
-  if (!rect.value) return null
-  const r = rect.value
-  let x = r.x + r.w - TOOLBAR_W
-  let y = r.y + r.h + GAP
-  if (y + TOOLBAR_H > props.height) {
-    // No room below: put it inside the selection's bottom-right.
-    y = r.y + r.h - TOOLBAR_H - GAP
-  }
-  if (x < 0) x = 0
-  if (x + TOOLBAR_W > props.width) x = props.width - TOOLBAR_W
-  return { x, y }
+const allAnnotations = computed(() => {
+  return draftAnnotation.value
+    ? [...annotations.value, draftAnnotation.value]
+    : annotations.value
 })
 
-const insideRect = (px: number, py: number, r: Rect | null) => {
+const selectionAnnotations = computed(() => {
+  if (!rect.value) return []
+  return allAnnotations.value.map((annotation) => ({
+    ...annotation,
+    points: annotation.points.map((point) => ({
+      x: rect.value!.x + point.x,
+      y: rect.value!.y + point.y,
+    })),
+  }))
+})
+
+const sizeLabel = computed(() => {
+  if (!rect.value) return ''
+  return `${Math.round(rect.value.w)} × ${Math.round(rect.value.h)}`
+})
+
+const rightToolbarPos = computed(() => {
+  if (!rect.value) return null
+  return placeToolbar(rect.value, 220, 40, 'right')
+})
+
+const leftToolbarPos = computed(() => {
+  if (!rect.value) return null
+  return placeToolbar(rect.value, 190, 40, 'left')
+})
+
+const handles = computed(() => {
+  if (!rect.value) return []
+  const r = rect.value
+  const cx = r.x + r.w / 2
+  const cy = r.y + r.h / 2
+  return [
+    { name: 'nw', x: r.x, y: r.y },
+    { name: 'n', x: cx, y: r.y },
+    { name: 'ne', x: r.x + r.w, y: r.y },
+    { name: 'e', x: r.x + r.w, y: cy },
+    { name: 'se', x: r.x + r.w, y: r.y + r.h },
+    { name: 's', x: cx, y: r.y + r.h },
+    { name: 'sw', x: r.x, y: r.y + r.h },
+    { name: 'w', x: r.x, y: cy },
+  ] as Array<{ name: ResizeHandle; x: number; y: number }>
+})
+
+function placeToolbar(
+  r: Rect,
+  toolbarW: number,
+  toolbarH: number,
+  side: 'left' | 'right'
+) {
+  const gap = 8
+  let x =
+    side === 'right'
+      ? r.x + r.w - toolbarW
+      : r.x
+  let y = r.y + r.h + gap
+  if (y + toolbarH > props.height) {
+    y = r.y + r.h - toolbarH - gap
+  }
+  x = clamp(x, 0, props.width - toolbarW)
+  return { x, y }
+}
+
+function clamp(value: number, min: number, max: number) {
+  return Math.max(min, Math.min(value, max))
+}
+
+function normalizeRect(a: Point, b: Point): Rect {
+  return {
+    x: clamp(Math.min(a.x, b.x), 0, props.width),
+    y: clamp(Math.min(a.y, b.y), 0, props.height),
+    w: Math.abs(b.x - a.x),
+    h: Math.abs(b.y - a.y),
+  }
+}
+
+function pointFromEvent(e: MouseEvent): Point {
+  return {
+    x: clamp(e.clientX, 0, props.width),
+    y: clamp(e.clientY, 0, props.height),
+  }
+}
+
+function localPoint(p: Point) {
+  if (!rect.value) return p
+  return {
+    x: clamp(p.x - rect.value.x, 0, rect.value.w),
+    y: clamp(p.y - rect.value.y, 0, rect.value.h),
+  }
+}
+
+function insideRect(p: Point, r: Rect | null) {
   if (!r) return false
-  return px >= r.x && px <= r.x + r.w && py >= r.y && py <= r.y + r.h
+  return p.x >= r.x && p.x <= r.x + r.w && p.y >= r.y && p.y <= r.y + r.h
+}
+
+function hitHandle(p: Point): ResizeHandle | null {
+  if (!rect.value) return null
+  const tolerance = 9
+  for (const handle of handles.value) {
+    if (
+      Math.abs(p.x - handle.x) <= tolerance &&
+      Math.abs(p.y - handle.y) <= tolerance
+    ) {
+      return handle.name
+    }
+  }
+  const r = rect.value
+  const nearX = p.x >= r.x - tolerance && p.x <= r.x + r.w + tolerance
+  const nearY = p.y >= r.y - tolerance && p.y <= r.y + r.h + tolerance
+  if (nearX && Math.abs(p.y - r.y) <= tolerance) return 'n'
+  if (nearX && Math.abs(p.y - (r.y + r.h)) <= tolerance) return 's'
+  if (nearY && Math.abs(p.x - r.x) <= tolerance) return 'w'
+  if (nearY && Math.abs(p.x - (r.x + r.w)) <= tolerance) return 'e'
+  return null
 }
 
 function onMouseDown(e: MouseEvent) {
   if (e.button !== 0) return
-  const px = e.clientX
-  const py = e.clientY
-  if (rect.value && insideRect(px, py, rect.value)) {
-    // Move existing selection.
+  paletteOpen.value = false
+  const p = pointFromEvent(e)
+  const handle = hitHandle(p)
+  if (handle && rect.value) {
+    dragMode.value = 'resizing'
+    resizeHandle.value = handle
+    dragAnchor.value = p
+    startRect.value = { ...rect.value }
+    return
+  }
+  if (rect.value && insideRect(p, rect.value)) {
     dragMode.value = 'moving'
-    dragAnchor.value = { x: px - rect.value.x, y: py - rect.value.y }
-  } else {
-    // Start a new selection.
-    dragMode.value = 'creating'
-    dragAnchor.value = { x: px, y: py }
-    rect.value = { x: px, y: py, w: 0, h: 0 }
+    dragAnchor.value = { x: p.x - rect.value.x, y: p.y - rect.value.y }
+    return
+  }
+  dragMode.value = 'creating'
+  dragAnchor.value = p
+  rect.value = { x: p.x, y: p.y, w: 0, h: 0 }
+  annotations.value = []
+  draftAnnotation.value = null
+}
+
+function onSelectionMouseDown(e: MouseEvent) {
+  if (e.button !== 0 || !rect.value) return
+  e.stopPropagation()
+  paletteOpen.value = false
+  const p = pointFromEvent(e)
+  const handle = hitHandle(p)
+  if (handle) {
+    dragMode.value = 'resizing'
+    resizeHandle.value = handle
+    dragAnchor.value = p
+    startRect.value = { ...rect.value }
+    return
+  }
+  dragMode.value = 'annotating'
+  const local = localPoint(p)
+  draftAnnotation.value = {
+    tool: activeTool.value,
+    color: activeColor.value,
+    points: [local],
   }
 }
 
 function onMouseMove(e: MouseEvent) {
   if (dragMode.value === 'idle') return
-  const px = e.clientX
-  const py = e.clientY
+  const p = pointFromEvent(e)
   if (dragMode.value === 'creating') {
-    const ax = dragAnchor.value.x
-    const ay = dragAnchor.value.y
-    rect.value = {
-      x: Math.min(ax, px),
-      y: Math.min(ay, py),
-      w: Math.abs(px - ax),
-      h: Math.abs(py - ay),
-    }
+    rect.value = normalizeRect(dragAnchor.value, p)
   } else if (dragMode.value === 'moving' && rect.value) {
-    let nx = px - dragAnchor.value.x
-    let ny = py - dragAnchor.value.y
-    // Clamp inside the screen so the selection cannot be dragged off-canvas.
-    nx = Math.max(0, Math.min(nx, props.width - rect.value.w))
-    ny = Math.max(0, Math.min(ny, props.height - rect.value.h))
-    rect.value = { ...rect.value, x: nx, y: ny }
+    rect.value = {
+      ...rect.value,
+      x: clamp(p.x - dragAnchor.value.x, 0, props.width - rect.value.w),
+      y: clamp(p.y - dragAnchor.value.y, 0, props.height - rect.value.h),
+    }
+  } else if (dragMode.value === 'resizing') {
+    resizeSelection(p)
+  } else if (dragMode.value === 'annotating' && draftAnnotation.value) {
+    if (activeTool.value === 'pen') {
+      draftAnnotation.value.points.push(localPoint(p))
+    } else {
+      draftAnnotation.value.points = [
+        draftAnnotation.value.points[0],
+        localPoint(p),
+      ]
+    }
   }
 }
 
 function onMouseUp() {
   if (dragMode.value === 'creating' && rect.value) {
-    // Discard zero/tiny selections — the user probably clicked accidentally.
     if (rect.value.w < 4 || rect.value.h < 4) {
       rect.value = null
     }
   }
+  if (dragMode.value === 'annotating' && draftAnnotation.value) {
+    if (draftAnnotation.value.points.length > 0) {
+      annotations.value.push(draftAnnotation.value)
+    }
+    draftAnnotation.value = null
+  }
   dragMode.value = 'idle'
+  resizeHandle.value = null
+  startRect.value = null
+}
+
+function resizeSelection(p: Point) {
+  if (!startRect.value || !resizeHandle.value) return
+  const r = startRect.value
+  let left = r.x
+  let top = r.y
+  let right = r.x + r.w
+  let bottom = r.y + r.h
+  if (resizeHandle.value.includes('w')) left = p.x
+  if (resizeHandle.value.includes('e')) right = p.x
+  if (resizeHandle.value.includes('n')) top = p.y
+  if (resizeHandle.value.includes('s')) bottom = p.y
+
+  left = clamp(left, 0, props.width)
+  right = clamp(right, 0, props.width)
+  top = clamp(top, 0, props.height)
+  bottom = clamp(bottom, 0, props.height)
+  rect.value = {
+    x: Math.min(left, right),
+    y: Math.min(top, bottom),
+    w: Math.abs(right - left),
+    h: Math.abs(bottom - top),
+  }
+}
+
+function selectTool(tool: Tool) {
+  activeTool.value = tool
+}
+
+function chooseColor(color: string) {
+  activeColor.value = color
+  paletteOpen.value = false
 }
 
 function onConfirm() {
   if (!rect.value) return
-  emit('confirm', { ...rect.value })
+  emit('confirm', {
+    rect: { ...rect.value },
+    annotations: annotations.value,
+  })
 }
 
 function onCancel() {
@@ -153,18 +333,16 @@ function onKeydown(e: KeyboardEvent) {
   }
 }
 
+function undoAnnotation() {
+  annotations.value.pop()
+}
+
 onMounted(() => {
   window.addEventListener('keydown', onKeydown)
 })
 onUnmounted(() => {
   window.removeEventListener('keydown', onKeydown)
 })
-
-// Selection size pill (Snipaste shows "WxH" near the top-left of selection).
-const sizeLabel = computed(() => {
-  if (!rect.value) return ''
-  return `${Math.round(rect.value.w)} × ${Math.round(rect.value.h)}`
-})
 </script>
 
 <template>
@@ -176,7 +354,6 @@ const sizeLabel = computed(() => {
     @mouseup="onMouseUp"
     @contextmenu.prevent="onCancel"
   >
-    <!-- Layer 1: mask with selection cut out over the live desktop -->
     <svg
       class="mask"
       :width="width"
@@ -185,21 +362,78 @@ const sizeLabel = computed(() => {
       preserveAspectRatio="none"
     >
       <path :d="maskPath" fill="rgba(0,0,0,0.45)" fill-rule="evenodd" />
-      <!-- Selection border, drawn separately so it stays crisp. -->
       <rect
         v-if="rect"
         :x="rect.x"
         :y="rect.y"
         :width="rect.w"
         :height="rect.h"
-        fill="none"
+        fill="transparent"
         stroke="#3b82f6"
         stroke-width="1.5"
         vector-effect="non-scaling-stroke"
       />
+      <g v-for="(annotation, index) in selectionAnnotations" :key="index">
+        <polyline
+          v-if="annotation.tool === 'pen'"
+          :points="annotation.points.map((p) => `${p.x},${p.y}`).join(' ')"
+          :stroke="annotation.color"
+          stroke-width="3"
+          stroke-linecap="round"
+          stroke-linejoin="round"
+          fill="none"
+        />
+        <rect
+          v-else-if="annotation.tool === 'rect' && annotation.points.length >= 2"
+          :x="Math.min(annotation.points[0].x, annotation.points[1].x)"
+          :y="Math.min(annotation.points[0].y, annotation.points[1].y)"
+          :width="Math.abs(annotation.points[1].x - annotation.points[0].x)"
+          :height="Math.abs(annotation.points[1].y - annotation.points[0].y)"
+          :stroke="annotation.color"
+          stroke-width="3"
+          fill="none"
+        />
+        <ellipse
+          v-else-if="annotation.tool === 'ellipse' && annotation.points.length >= 2"
+          :cx="(annotation.points[0].x + annotation.points[1].x) / 2"
+          :cy="(annotation.points[0].y + annotation.points[1].y) / 2"
+          :rx="Math.abs(annotation.points[1].x - annotation.points[0].x) / 2"
+          :ry="Math.abs(annotation.points[1].y - annotation.points[0].y) / 2"
+          :stroke="annotation.color"
+          stroke-width="3"
+          fill="none"
+        />
+      </g>
     </svg>
 
-    <!-- Layer 3a: size readout floating above the selection -->
+    <div
+      v-if="rect"
+      class="selection-hit-area"
+      :style="{
+        left: rect.x + 'px',
+        top: rect.y + 'px',
+        width: rect.w + 'px',
+        height: rect.h + 'px',
+      }"
+      @mousedown="onSelectionMouseDown"
+    />
+
+    <div
+      v-for="handle in handles"
+      :key="handle.name"
+      class="resize-handle"
+      :class="`handle-${handle.name}`"
+      :style="{ left: handle.x + 'px', top: handle.y + 'px' }"
+      @mousedown.stop="
+        (event) => {
+          dragMode = 'resizing'
+          resizeHandle = handle.name
+          dragAnchor = pointFromEvent(event)
+          startRect = rect ? { ...rect } : null
+        }
+      "
+    />
+
     <div
       v-if="rect && rect.w > 0 && rect.h > 0"
       class="size-pill"
@@ -211,11 +445,80 @@ const sizeLabel = computed(() => {
       {{ sizeLabel }}
     </div>
 
-    <!-- Layer 3b: action toolbar -->
     <div
-      v-if="toolbarPos && rect && rect.w >= 4 && rect.h >= 4"
-      class="toolbar"
-      :style="{ left: toolbarPos.x + 'px', top: toolbarPos.y + 'px' }"
+      v-if="leftToolbarPos && rect && rect.w >= 4 && rect.h >= 4"
+      class="toolbar mark-toolbar"
+      :style="{ left: leftToolbarPos.x + 'px', top: leftToolbarPos.y + 'px' }"
+      @mousedown.stop
+    >
+      <button
+        class="icon-btn"
+        :class="{ active: activeTool === 'pen' }"
+        title="划线标记"
+        @click="selectTool('pen')"
+      >
+        <svg viewBox="0 0 24 24" aria-hidden="true">
+          <path d="M4 20c4-1 6-3 8-7l5-9 3 2-5 9c-2 4-5 6-9 7z" />
+          <path d="M14 5l5 3" />
+        </svg>
+      </button>
+      <button
+        class="icon-btn"
+        :class="{ active: activeTool === 'rect' }"
+        title="矩形标记"
+        @click="selectTool('rect')"
+      >
+        <svg viewBox="0 0 24 24" aria-hidden="true">
+          <rect x="5" y="6" width="14" height="12" rx="1.5" />
+        </svg>
+      </button>
+      <button
+        class="icon-btn"
+        :class="{ active: activeTool === 'ellipse' }"
+        title="圆形标记"
+        @click="selectTool('ellipse')"
+      >
+        <svg viewBox="0 0 24 24" aria-hidden="true">
+          <circle cx="12" cy="12" r="7" />
+        </svg>
+      </button>
+      <div class="color-wrap">
+        <button
+          class="icon-btn color-btn"
+          title="选择标记颜色"
+          @click="paletteOpen = !paletteOpen"
+        >
+          <span :style="{ background: activeColor }" />
+        </button>
+        <div v-if="paletteOpen" class="palette">
+          <button
+            v-for="color in colors"
+            :key="color"
+            class="swatch"
+            :class="{ selected: color === activeColor }"
+            :style="{ background: color }"
+            :title="color"
+            @click="chooseColor(color)"
+          />
+        </div>
+      </div>
+      <button
+        class="icon-btn"
+        :disabled="annotations.length === 0"
+        title="撤销上一处标记"
+        @click="undoAnnotation"
+      >
+        <svg viewBox="0 0 24 24" aria-hidden="true">
+          <path d="M9 7H4v5" />
+          <path d="M4 7c3-3 8-4 12-1 4 3 4 9 0 12-2 1-4 2-7 1" />
+        </svg>
+      </button>
+    </div>
+
+    <div
+      v-if="rightToolbarPos && rect && rect.w >= 4 && rect.h >= 4"
+      class="toolbar action-toolbar"
+      :style="{ left: rightToolbarPos.x + 'px', top: rightToolbarPos.y + 'px' }"
       @mousedown.stop
     >
       <button class="btn cancel" @click="onCancel" title="Esc">Cancel</button>
@@ -224,7 +527,6 @@ const sizeLabel = computed(() => {
       </button>
     </div>
 
-    <!-- Hint shown before the user has dragged anything. -->
     <div v-if="!rect" class="hint">
       Drag to select an area &nbsp;·&nbsp; Esc to cancel
     </div>
@@ -248,6 +550,38 @@ const sizeLabel = computed(() => {
   pointer-events: none;
 }
 
+.selection-hit-area {
+  position: absolute;
+  cursor: crosshair;
+}
+
+.resize-handle {
+  position: absolute;
+  width: 10px;
+  height: 10px;
+  transform: translate(-50%, -50%);
+  border: 1px solid #fff;
+  background: #3b82f6;
+  box-shadow: 0 1px 5px rgba(0, 0, 0, 0.35);
+  z-index: 3;
+}
+.handle-n,
+.handle-s {
+  cursor: ns-resize;
+}
+.handle-e,
+.handle-w {
+  cursor: ew-resize;
+}
+.handle-nw,
+.handle-se {
+  cursor: nwse-resize;
+}
+.handle-ne,
+.handle-sw {
+  cursor: nesw-resize;
+}
+
 .size-pill {
   position: absolute;
   padding: 2px 8px;
@@ -258,7 +592,6 @@ const sizeLabel = computed(() => {
   border-radius: 4px;
   pointer-events: none;
   font-variant-numeric: tabular-nums;
-  letter-spacing: 0.02em;
 }
 
 .toolbar {
@@ -266,11 +599,26 @@ const sizeLabel = computed(() => {
   display: flex;
   gap: 6px;
   align-items: center;
+  height: 32px;
   padding: 4px;
   background: rgba(28, 28, 32, 0.94);
   border-radius: 8px;
   box-shadow: 0 6px 22px rgba(0, 0, 0, 0.4);
   cursor: default;
+  z-index: 4;
+}
+
+.mark-toolbar {
+  width: 190px;
+}
+.action-toolbar {
+  width: 220px;
+}
+
+.btn,
+.icon-btn,
+.swatch {
+  font-family: inherit;
 }
 
 .btn {
@@ -280,8 +628,6 @@ const sizeLabel = computed(() => {
   font-size: 12px;
   font-weight: 500;
   cursor: pointer;
-  font-family: inherit;
-  transition: background-color 120ms ease;
 }
 .btn.cancel {
   background: transparent;
@@ -298,6 +644,69 @@ const sizeLabel = computed(() => {
   background: #2563eb;
 }
 
+.icon-btn {
+  display: grid;
+  place-items: center;
+  width: 28px;
+  height: 28px;
+  border: 0;
+  border-radius: 5px;
+  color: #d1d5db;
+  background: transparent;
+  cursor: pointer;
+}
+.icon-btn:hover:not(:disabled),
+.icon-btn.active {
+  color: #fff;
+  background: rgba(255, 255, 255, 0.12);
+}
+.icon-btn:disabled {
+  opacity: 0.35;
+  cursor: not-allowed;
+}
+.icon-btn svg {
+  width: 18px;
+  height: 18px;
+  fill: none;
+  stroke: currentColor;
+  stroke-width: 2;
+  stroke-linecap: round;
+  stroke-linejoin: round;
+}
+
+.color-wrap {
+  position: relative;
+}
+.color-btn span {
+  width: 16px;
+  height: 16px;
+  border: 1px solid rgba(255, 255, 255, 0.7);
+  box-shadow: inset 0 0 0 1px rgba(0, 0, 0, 0.18);
+}
+.palette {
+  position: absolute;
+  left: 0;
+  bottom: 36px;
+  display: grid;
+  grid-template-columns: repeat(5, 22px);
+  gap: 6px;
+  padding: 8px;
+  background: rgba(28, 28, 32, 0.96);
+  border-radius: 8px;
+  box-shadow: 0 8px 26px rgba(0, 0, 0, 0.45);
+}
+.swatch {
+  width: 22px;
+  height: 22px;
+  border: 1px solid rgba(255, 255, 255, 0.55);
+  border-radius: 4px;
+  cursor: pointer;
+}
+.swatch.selected {
+  outline: 2px solid #fff;
+  outline-offset: 2px;
+}
+
 .hint {
   position: absolute;
   left: 50%;
@@ -309,6 +718,5 @@ const sizeLabel = computed(() => {
   background: rgba(0, 0, 0, 0.5);
   border-radius: 999px;
   pointer-events: none;
-  letter-spacing: 0.02em;
 }
 </style>
diff --git a/frontend/wailsjs/go/main/App.d.ts b/frontend/wailsjs/go/main/App.d.ts
index dac05f3..db9b728 100755
--- a/frontend/wailsjs/go/main/App.d.ts
+++ b/frontend/wailsjs/go/main/App.d.ts
@@ -9,9 +9,9 @@ export function CancelRegion():Promise<void>;
 
 export function CaptureNow():Promise<void>;
 
-export function ConfirmNativeRegion(arg1:main.RegionRect):Promise<void>;
+export function ConfirmNativeRegion(arg1:main.CaptureResult):Promise<void>;
 
-export function ConfirmRegion(arg1:main.RegionRect):Promise<void>;
+export function ConfirmRegion(arg1:main.CaptureResult):Promise<void>;
 
 export function GetConfig():Promise<domain.AppConfig>;
 
diff --git a/frontend/wailsjs/go/models.ts b/frontend/wailsjs/go/models.ts
index 79d2781..3198b1b 100755
--- a/frontend/wailsjs/go/models.ts
+++ b/frontend/wailsjs/go/models.ts
@@ -1,5 +1,58 @@
+export namespace application {
+
+	export class Point {
+	    x: number;
+	    y: number;
+
+	    static createFrom(source: any = {}) {
+	        return new Point(source);
+	    }
+
+	    constructor(source: any = {}) {
+	        if ('string' === typeof source) source = JSON.parse(source);
+	        this.x = source["x"];
+	        this.y = source["y"];
+	    }
+	}
+	export class Annotation {
+	    tool: string;
+	    color: string;
+	    points: Point[];
+
+	    static createFrom(source: any = {}) {
+	        return new Annotation(source);
+	    }
+
+	    constructor(source: any = {}) {
+	        if ('string' === typeof source) source = JSON.parse(source);
+	        this.tool = source["tool"];
+	        this.color = source["color"];
+	        this.points = this.convertValues(source["points"], Point);
+	    }
+
+		convertValues(a: any, classs: any, asMap: boolean = false): any {
+		    if (!a) {
+		        return a;
+		    }
+		    if (a.slice && a.map) {
+		        return (a as any[]).map(elem => this.convertValues(elem, classs));
+		    } else if ("object" === typeof a) {
+		        if (asMap) {
+		            for (const key of Object.keys(a)) {
+		                a[key] = new classs(a[key]);
+		            }
+		            return a;
+		        }
+		        return new classs(a);
+		    }
+		    return a;
+		}
+	}
+
+}
+
 export namespace domain {
-	
+
 	export class S3Config {
 	    endpoint: string;
 	    region: string;
@@ -9,11 +62,11 @@ export namespace domain {
 	    pathPrefix: string;
 	    publicUrlBase: string;
 	    usePathStyle: boolean;
-	
+
 	    static createFrom(source: any = {}) {
 	        return new S3Config(source);
 	    }
-	
+
 	    constructor(source: any = {}) {
 	        if ('string' === typeof source) source = JSON.parse(source);
 	        this.endpoint = source["endpoint"];
@@ -29,17 +82,17 @@ export namespace domain {
 	export class AppConfig {
 	    hotkey: string;
 	    s3: S3Config;
-	
+
 	    static createFrom(source: any = {}) {
 	        return new AppConfig(source);
 	    }
-	
+
 	    constructor(source: any = {}) {
 	        if ('string' === typeof source) source = JSON.parse(source);
 	        this.hotkey = source["hotkey"];
 	        this.s3 = this.convertValues(source["s3"], S3Config);
 	    }
-	
+
 		convertValues(a: any, classs: any, asMap: boolean = false): any {
 		    if (!a) {
 		        return a;
@@ -62,17 +115,17 @@ export namespace domain {
 }
 
 export namespace main {
-	
+
 	export class RegionRect {
 	    x: number;
 	    y: number;
 	    w: number;
 	    h: number;
-	
+
 	    static createFrom(source: any = {}) {
 	        return new RegionRect(source);
 	    }
-	
+
 	    constructor(source: any = {}) {
 	        if ('string' === typeof source) source = JSON.parse(source);
 	        this.x = source["x"];
@@ -81,6 +134,38 @@ export namespace main {
 	        this.h = source["h"];
 	    }
 	}
+	export class CaptureResult {
+	    rect: RegionRect;
+	    annotations: application.Annotation[];
+
+	    static createFrom(source: any = {}) {
+	        return new CaptureResult(source);
+	    }
+
+	    constructor(source: any = {}) {
+	        if ('string' === typeof source) source = JSON.parse(source);
+	        this.rect = this.convertValues(source["rect"], RegionRect);
+	        this.annotations = this.convertValues(source["annotations"], application.Annotation);
+	    }
+
+		convertValues(a: any, classs: any, asMap: boolean = false): any {
+		    if (!a) {
+		        return a;
+		    }
+		    if (a.slice && a.map) {
+		        return (a as any[]).map(elem => this.convertValues(elem, classs));
+		    } else if ("object" === typeof a) {
+		        if (asMap) {
+		            for (const key of Object.keys(a)) {
+		                a[key] = new classs(a[key]);
+		            }
+		            return a;
+		        }
+		        return new classs(a);
+		    }
+		    return a;
+		}
+	}
 
 }
 
diff --git a/internal/application/annotation.go b/internal/application/annotation.go
new file mode 100644
index 0000000..dd99041
--- /dev/null
+++ b/internal/application/annotation.go
@@ -0,0 +1,182 @@
+package application
+
+import (
+	"bytes"
+	"fmt"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"math"
+	"strconv"
+	"strings"
+)
+
+// Annotation describes a user-drawn mark relative to the selected screenshot.
+// Coordinates are logical pixels in the same coordinate system as the overlay.
+type Annotation struct {
+	Tool   string  `json:"tool"`
+	Color  string  `json:"color"`
+	Points []Point `json:"points"`
+}
+
+type Point struct {
+	X float64 `json:"x"`
+	Y float64 `json:"y"`
+}
+
+// ApplyAnnotations decodes a PNG, draws all annotations, and re-encodes it.
+func ApplyAnnotations(pngBytes []byte, annotations []Annotation, scale float64) ([]byte, error) {
+	if len(annotations) == 0 {
+		return pngBytes, nil
+	}
+	if scale <= 0 {
+		scale = 1
+	}
+
+	src, err := png.Decode(bytes.NewReader(pngBytes))
+	if err != nil {
+		return nil, fmt.Errorf("decode annotated png: %w", err)
+	}
+	bounds := src.Bounds()
+	dst := image.NewRGBA(image.Rect(0, 0, bounds.Dx(), bounds.Dy()))
+	draw.Draw(dst, dst.Bounds(), src, bounds.Min, draw.Src)
+
+	for _, ann := range annotations {
+		c, err := parseHexColor(ann.Color)
+		if err != nil {
+			c = color.RGBA{R: 59, G: 130, B: 246, A: 255}
+		}
+		width := int(math.Max(2, math.Round(3*scale)))
+		switch ann.Tool {
+		case "pen":
+			drawPolyline(dst, ann.Points, scale, width, c)
+		case "rect":
+			drawRectOutline(dst, ann.Points, scale, width, c)
+		case "ellipse":
+			drawEllipseOutline(dst, ann.Points, scale, width, c)
+		}
+	}
+
+	var buf bytes.Buffer
+	if err := png.Encode(&buf, dst); err != nil {
+		return nil, fmt.Errorf("encode annotated png: %w", err)
+	}
+	return buf.Bytes(), nil
+}
+
+func parseHexColor(hex string) (color.RGBA, error) {
+	value := strings.TrimPrefix(strings.TrimSpace(hex), "#")
+	if len(value) != 6 {
+		return color.RGBA{}, fmt.Errorf("invalid color %q", hex)
+	}
+	n, err := strconv.ParseUint(value, 16, 32)
+	if err != nil {
+		return color.RGBA{}, err
+	}
+	return color.RGBA{
+		R: uint8(n >> 16),
+		G: uint8(n >> 8),
+		B: uint8(n),
+		A: 255,
+	}, nil
+}
+
+func drawPolyline(img *image.RGBA, points []Point, scale float64, width int, c color.RGBA) {
+	if len(points) == 1 {
+		drawDot(img, scalePoint(points[0], scale), width, c)
+		return
+	}
+	for i := 1; i < len(points); i++ {
+		drawLine(img, scalePoint(points[i-1], scale), scalePoint(points[i], scale), width, c)
+	}
+}
+
+func drawRectOutline(img *image.RGBA, points []Point, scale float64, width int, c color.RGBA) {
+	if len(points) < 2 {
+		return
+	}
+	a := scalePoint(points[0], scale)
+	b := scalePoint(points[len(points)-1], scale)
+	x1, x2 := ordered(a.X, b.X)
+	y1, y2 := ordered(a.Y, b.Y)
+	drawLine(img, Point{X: x1, Y: y1}, Point{X: x2, Y: y1}, width, c)
+	drawLine(img, Point{X: x2, Y: y1}, Point{X: x2, Y: y2}, width, c)
+	drawLine(img, Point{X: x2, Y: y2}, Point{X: x1, Y: y2}, width, c)
+	drawLine(img, Point{X: x1, Y: y2}, Point{X: x1, Y: y1}, width, c)
+}
+
+func drawEllipseOutline(img *image.RGBA, points []Point, scale float64, width int, c color.RGBA) {
+	if len(points) < 2 {
+		return
+	}
+	a := scalePoint(points[0], scale)
+	b := scalePoint(points[len(points)-1], scale)
+	x1, x2 := ordered(a.X, b.X)
+	y1, y2 := ordered(a.Y, b.Y)
+	rx := (x2 - x1) / 2
+	ry := (y2 - y1) / 2
+	if rx <= 0 || ry <= 0 {
+		return
+	}
+	cx := x1 + rx
+	cy := y1 + ry
+	steps := int(math.Max(48, math.Ceil(2*math.Pi*math.Max(rx, ry)/4)))
+	prev := Point{
+		X: cx + rx,
+		Y: cy,
+	}
+	for i := 1; i <= steps; i++ {
+		theta := 2 * math.Pi * float64(i) / float64(steps)
+		next := Point{
+			X: cx + rx*math.Cos(theta),
+			Y: cy + ry*math.Sin(theta),
+		}
+		drawLine(img, prev, next, width, c)
+		prev = next
+	}
+}
+
+func drawLine(img *image.RGBA, a, b Point, width int, c color.RGBA) {
+	dx := b.X - a.X
+	dy := b.Y - a.Y
+	steps := int(math.Max(math.Abs(dx), math.Abs(dy)))
+	if steps == 0 {
+		drawDot(img, a, width, c)
+		return
+	}
+	for i := 0; i <= steps; i++ {
+		t := float64(i) / float64(steps)
+		drawDot(img, Point{X: a.X + dx*t, Y: a.Y + dy*t}, width, c)
+	}
+}
+
+func drawDot(img *image.RGBA, p Point, width int, c color.RGBA) {
+	radius := float64(width) / 2
+	minX := int(math.Floor(p.X - radius))
+	maxX := int(math.Ceil(p.X + radius))
+	minY := int(math.Floor(p.Y - radius))
+	maxY := int(math.Ceil(p.Y + radius))
+	bounds := img.Bounds()
+	for y := minY; y <= maxY; y++ {
+		for x := minX; x <= maxX; x++ {
+			if !image.Pt(x, y).In(bounds) {
+				continue
+			}
+			if math.Hypot(float64(x)-p.X, float64(y)-p.Y) <= radius {
+				img.SetRGBA(x, y, c)
+			}
+		}
+	}
+}
+
+func scalePoint(p Point, scale float64) Point {
+	return Point{X: p.X * scale, Y: p.Y * scale}
+}
+
+func ordered(a, b float64) (float64, float64) {
+	if a < b {
+		return a, b
+	}
+	return b, a
+}
diff --git a/internal/application/annotation_test.go b/internal/application/annotation_test.go
new file mode 100644
index 0000000..994c5b9
--- /dev/null
+++ b/internal/application/annotation_test.go
@@ -0,0 +1,53 @@
+package application
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"testing"
+)
+
+func TestApplyAnnotationsDrawsIntoPNG(t *testing.T) {
+	src := image.NewRGBA(image.Rect(0, 0, 40, 40))
+	draw.Draw(src, src.Bounds(), &image.Uniform{C: color.White}, image.Point{}, draw.Src)
+
+	var buf bytes.Buffer
+	if err := png.Encode(&buf, src); err != nil {
+		t.Fatalf("encode source: %v", err)
+	}
+
+	out, err := ApplyAnnotations(buf.Bytes(), []Annotation{
+		{
+			Tool:  "rect",
+			Color: "#ef4444",
+			Points: []Point{
+				{X: 5, Y: 5},
+				{X: 30, Y: 30},
+			},
+		},
+	}, 1)
+	if err != nil {
+		t.Fatalf("apply annotations: %v", err)
+	}
+
+	img, err := png.Decode(bytes.NewReader(out))
+	if err != nil {
+		t.Fatalf("decode output: %v", err)
+	}
+	if got := color.RGBAModel.Convert(img.At(5, 5)).(color.RGBA); got.R != 0xef || got.G != 0x44 || got.B != 0x44 {
+		t.Fatalf("expected annotated pixel at rectangle edge, got %#v", got)
+	}
+}
+
+func TestApplyAnnotationsNoAnnotationsReturnsOriginalBytes(t *testing.T) {
+	original := []byte("not decoded when no annotations")
+	out, err := ApplyAnnotations(original, nil, 1)
+	if err != nil {
+		t.Fatalf("apply annotations: %v", err)
+	}
+	if !bytes.Equal(out, original) {
+		t.Fatalf("expected original bytes")
+	}
+}
diff --git a/native_overlay_callbacks_darwin.go b/native_overlay_callbacks_darwin.go
index 8185bf8..9649b04 100644
--- a/native_overlay_callbacks_darwin.go
+++ b/native_overlay_callbacks_darwin.go
@@ -5,7 +5,7 @@ package main
 import "C"
 
 //export nativeOverlayConfirm
-func nativeOverlayConfirm(x, y, w, h C.int) {
+func nativeOverlayConfirm(x, y, w, h C.int, annotationsJSON *C.char) {
 	nativeOverlayState.Lock()
 	app := nativeOverlayState.app
 	nativeOverlayState.app = nil
@@ -13,12 +13,16 @@ func nativeOverlayConfirm(x, y, w, h C.int) {
 	if app == nil {
 		return
 	}
+	rawAnnotations := C.GoString(annotationsJSON)
 	go func() {
-		_ = app.ConfirmNativeRegion(RegionRect{
-			X: int(x),
-			Y: int(y),
-			W: int(w),
-			H: int(h),
+		_ = app.ConfirmNativeRegion(CaptureResult{
+			Rect: RegionRect{
+				X: int(x),
+				Y: int(y),
+				W: int(w),
+				H: int(h),
+			},
+			Annotations: parseNativeAnnotations(rawAnnotations),
 		})
 	}()
 }
diff --git a/native_overlay_darwin.go b/native_overlay_darwin.go
index 1a7e019..b887b07 100644
--- a/native_overlay_darwin.go
+++ b/native_overlay_darwin.go
@@ -7,9 +7,10 @@ package main
 #cgo LDFLAGS: -framework AppKit -framework CoreGraphics
 #include <math.h>
 #include <dispatch/dispatch.h>
+#import <objc/runtime.h>
 #import <AppKit/AppKit.h>
 
-extern void nativeOverlayConfirm(int x, int y, int w, int h);
+extern void nativeOverlayConfirm(int x, int y, int w, int h, const char *annotationsJSON);
 extern void nativeOverlayCancel(void);
 
 static NSWindow *nativeOverlayWindow = nil;
@@ -27,11 +28,25 @@ static id nativeOverlayKeyMonitor = nil;
 @property BOOL hasSelection;
 @property BOOL creating;
 @property BOOL moving;
+@property BOOL resizing;
+@property BOOL annotating;
 @property NSRect selection;
 @property NSPoint anchor;
 @property NSPoint moveOffset;
+@property NSRect resizeStart;
+@property NSString *resizeHandle;
+@property NSString *activeTool;
+@property(strong) NSColor *activeColor;
+@property(strong) NSMutableArray<NSDictionary *> *annotations;
+@property(strong) NSMutableDictionary *draftAnnotation;
 @property(strong) NSButton *cancelButton;
 @property(strong) NSButton *uploadButton;
+@property(strong) NSButton *penButton;
+@property(strong) NSButton *rectButton;
+@property(strong) NSButton *ellipseButton;
+@property(strong) NSButton *colorButton;
+@property(strong) NSButton *undoButton;
+@property(strong) NSView *paletteView;
 @property(strong) NSTextField *sizeLabel;
 @property(strong) NSTextField *hintLabel;
 - (void)syncControls;
@@ -50,17 +65,28 @@ static id nativeOverlayKeyMonitor = nil;
         [self setWantsLayer:YES];
         [[self layer] setBackgroundColor:[[NSColor clearColor] CGColor]];
 
+        _activeTool = nil;
+        _activeColor = [NSColor colorWithCalibratedRed:239.0/255.0 green:68.0/255.0 blue:68.0/255.0 alpha:1.0];
+        _annotations = [NSMutableArray array];
+
         _cancelButton = [NSButton buttonWithTitle:@"Cancel" target:self action:@selector(cancelSelection)];
         _uploadButton = [NSButton buttonWithTitle:@"Upload & copy" target:self action:@selector(confirmSelection)];
+        _penButton = [NSButton buttonWithTitle:@"" target:self action:@selector(selectPen)];
+        _rectButton = [NSButton buttonWithTitle:@"" target:self action:@selector(selectRect)];
+        _ellipseButton = [NSButton buttonWithTitle:@"" target:self action:@selector(selectEllipse)];
+        _colorButton = [NSButton buttonWithTitle:@"" target:self action:@selector(togglePalette)];
+        _undoButton = [NSButton buttonWithTitle:@"" target:self action:@selector(undoAnnotation)];
+        _paletteView = [[NSView alloc] initWithFrame:NSZeroRect];
         _sizeLabel = [NSTextField labelWithString:@""];
         _hintLabel = [NSTextField labelWithString:@"Drag to select an area  ·  Esc to cancel"];
         [self styleControls];
 
-        for (NSView *view in @[_cancelButton, _uploadButton, _sizeLabel, _hintLabel]) {
+        for (NSView *view in @[_cancelButton, _uploadButton, _penButton, _rectButton, _ellipseButton, _colorButton, _undoButton, _paletteView, _sizeLabel, _hintLabel]) {
             [self addSubview:view];
         }
-        [_cancelButton setHidden:YES];
-        [_uploadButton setHidden:YES];
+        for (NSView *view in @[_cancelButton, _uploadButton, _penButton, _rectButton, _ellipseButton, _colorButton, _undoButton, _paletteView]) {
+            [view setHidden:YES];
+        }
         [_sizeLabel setHidden:YES];
 
         [_sizeLabel setTextColor:[NSColor whiteColor]];
@@ -79,6 +105,21 @@ static id nativeOverlayKeyMonitor = nil;
     return self;
 }
 
+- (NSString *)hexForColor:(NSColor *)color {
+    NSColor *rgb = [color colorUsingColorSpace:[NSColorSpace sRGBColorSpace]];
+    NSInteger r = (NSInteger)llround([rgb redComponent] * 255.0);
+    NSInteger g = (NSInteger)llround([rgb greenComponent] * 255.0);
+    NSInteger b = (NSInteger)llround([rgb blueComponent] * 255.0);
+    return [NSString stringWithFormat:@"#%02lx%02lx%02lx", (long)r, (long)g, (long)b];
+}
+
+- (NSImage *)iconFromSVG:(NSString *)svg {
+    NSData *data = [svg dataUsingEncoding:NSUTF8StringEncoding];
+    NSImage *image = [[NSImage alloc] initWithData:data];
+    [image setTemplate:YES];
+    return image;
+}
+
 - (void)styleButton:(NSButton *)button background:(NSColor *)background foreground:(NSColor *)foreground {
     [button setBordered:NO];
     [button setBezelStyle:NSBezelStyleRegularSquare];
@@ -91,6 +132,20 @@ static id nativeOverlayKeyMonitor = nil;
     [button setAttributedTitle:title];
 }
 
+- (void)styleIconButton:(NSButton *)button image:(NSImage *)image {
+    [button setBordered:NO];
+    [button setBezelStyle:NSBezelStyleRegularSquare];
+    [button setImagePosition:NSImageOnly];
+    [button setImageScaling:NSImageScaleProportionallyDown];
+    if (@available(macOS 10.14, *)) {
+        [button setContentTintColor:[NSColor whiteColor]];
+    }
+    [button setImage:image];
+    [button setWantsLayer:YES];
+    [[button layer] setCornerRadius:5];
+    [[button layer] setBackgroundColor:[[NSColor clearColor] CGColor]];
+}
+
 - (void)styleControls {
     [self styleButton:_cancelButton
            background:[NSColor colorWithCalibratedWhite:0.12 alpha:0.96]
@@ -98,6 +153,14 @@ static id nativeOverlayKeyMonitor = nil;
     [self styleButton:_uploadButton
            background:[NSColor colorWithCalibratedRed:59.0/255.0 green:130.0/255.0 blue:246.0/255.0 alpha:1.0]
            foreground:[NSColor whiteColor]];
+    [self styleIconButton:_penButton image:[self iconFromSVG:@"<svg viewBox='0 0 1024 1024' xmlns='http://www.w3.org/2000/svg'><path d='M742.72 752.064c-29.696 28.576-42.976 48.96-42.976 77.12 0 98.4 143.776 142.464 229.728 65.536l-21.344-23.84c-66.976 59.936-176.384 26.4-176.384-41.696 0-16.832 9.28-31.104 33.184-54.08l13.44-12.736c61.024-58.016 75.328-102.72 29.312-179.84-43.84-73.44-96.8-88.288-162.784-50.56-47.232 27.04-68.64 47.456-208.32 190.4-70.624 72.288-153.92 77.088-217.344 26.784-59.712-47.328-79.872-127.36-42.176-188.64 24.512-39.84 62.656-72.896 136.64-124.48 5.952-4.192 27.04-18.816 31.104-21.664 12.16-8.448 21.536-15.104 30.4-21.536 107.552-78.272 140.8-139.136 86.048-219.904-76.992-113.472-202.304-90.016-367.744 61.472l21.6 23.616c153.088-140.224 256.896-159.616 319.68-67.104 41.632 61.408 16.896 106.688-78.4 176.032-8.64 6.304-17.92 12.832-29.888 21.184l-31.136 21.632c-77.504 54.08-117.984 89.184-145.536 133.984-46.784 76.032-22.176 173.664 49.536 230.496 76.224 60.416 177.952 54.56 260.096-29.504 136.16-139.36 158.08-160.224 201.312-184.96 50.656-28.96 84.416-19.52 119.424 39.168 36.896 61.824 27.52 91.392-23.808 140.16 0.096-0.064-10.976 10.368-13.632 12.96z' fill='white'/></svg>"]];
+    [self styleIconButton:_rectButton image:[self iconFromSVG:@"<svg viewBox='0 0 1024 1024' xmlns='http://www.w3.org/2000/svg'><path d='M96 96h832v832H96V96z m32 32v768h768V128H128z' fill='white'/></svg>"]];
+    [self styleIconButton:_ellipseButton image:[self iconFromSVG:@"<svg viewBox='0 0 1024 1024' xmlns='http://www.w3.org/2000/svg'><path d='M512 928c229.76 0 416-186.24 416-416S741.76 96 512 96 96 282.24 96 512s186.24 416 416 416z m0-32C299.936 896 128 724.064 128 512S299.936 128 512 128s384 171.936 384 384-171.936 384-384 384z' fill='white'/></svg>"]];
+    [self styleIconButton:_colorButton image:nil];
+    [self styleIconButton:_undoButton image:[self iconFromSVG:@"<svg viewBox='0 0 1024 1024' xmlns='http://www.w3.org/2000/svg'><g transform='translate(1024 0) scale(-1 1)'><path d='M838.976 288l-169.344-162.56a16 16 0 1 1 22.144-23.04l213.632 204.992-213.312 215.84a16 16 0 0 1-22.784-22.464L847.936 320H454.56c-164.192 0-297.28 128.96-297.28 288s133.088 288 297.28 288H704v32h-242.784C266.88 928 128 784.736 128 608S266.88 288 461.248 288h377.728z' fill='white'/></g></svg>"]];
+    [_paletteView setWantsLayer:YES];
+    [[_paletteView layer] setCornerRadius:8];
+    [[_paletteView layer] setBackgroundColor:[[NSColor colorWithCalibratedWhite:0.11 alpha:0.96] CGColor]];
 }
 
 - (void)drawRect:(NSRect)dirtyRect {
@@ -133,23 +196,156 @@ static id nativeOverlayKeyMonitor = nil;
         [corners lineToPoint:NSMakePoint(NSMinX(_selection), NSMaxY(_selection) - corner)];
         [corners setLineWidth:3];
         [corners stroke];
+
+        [self drawAnnotations];
+        [self drawResizeHandles];
     } else {
         NSRectFill(self.bounds);
     }
 }
 
+- (void)drawResizeHandles {
+    NSArray *points = @[
+        [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMinY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMidX(_selection), NSMinY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMinY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMidY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMaxY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMidX(_selection), NSMaxY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMaxY(_selection))],
+        [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMidY(_selection))]
+    ];
+    [[NSColor whiteColor] setStroke];
+    [[NSColor colorWithCalibratedRed:59.0/255.0 green:130.0/255.0 blue:246.0/255.0 alpha:1.0] setFill];
+    for (NSValue *value in points) {
+        NSPoint p = [value pointValue];
+        NSRect handleRect = NSMakeRect(p.x - 5, p.y - 5, 10, 10);
+        NSBezierPath *path = [NSBezierPath bezierPathWithRect:handleRect];
+        [path fill];
+        [path stroke];
+    }
+}
+
+- (void)drawAnnotations {
+    NSMutableArray *items = [NSMutableArray arrayWithArray:_annotations];
+    if (_draftAnnotation != nil) {
+        [items addObject:_draftAnnotation];
+    }
+    for (NSDictionary *item in items) {
+        NSString *tool = item[@"tool"];
+        NSColor *color = item[@"nsColor"];
+        NSArray *points = item[@"points"];
+        if (points.count == 0) {
+            continue;
+        }
+        [color setStroke];
+        NSBezierPath *path = [NSBezierPath bezierPath];
+        [path setLineWidth:3];
+        [path setLineCapStyle:NSLineCapStyleRound];
+        [path setLineJoinStyle:NSLineJoinStyleRound];
+        if ([tool isEqualToString:@"pen"]) {
+            NSPoint first = [points[0] pointValue];
+            [path moveToPoint:NSMakePoint(_selection.origin.x + first.x, _selection.origin.y + first.y)];
+            for (NSUInteger i = 1; i < points.count; i++) {
+                NSPoint point = [points[i] pointValue];
+                [path lineToPoint:NSMakePoint(_selection.origin.x + point.x, _selection.origin.y + point.y)];
+            }
+            [path stroke];
+        } else if (points.count >= 2) {
+            NSPoint a = [points[0] pointValue];
+            NSPoint b = [[points lastObject] pointValue];
+            NSRect r = NSMakeRect(
+                _selection.origin.x + MIN(a.x, b.x),
+                _selection.origin.y + MIN(a.y, b.y),
+                fabs(b.x - a.x),
+                fabs(b.y - a.y));
+            if ([tool isEqualToString:@"rect"]) {
+                NSBezierPath *rectPath = [NSBezierPath bezierPathWithRect:r];
+                [rectPath setLineWidth:3];
+                [rectPath stroke];
+            } else if ([tool isEqualToString:@"ellipse"]) {
+                NSBezierPath *ellipsePath = [NSBezierPath bezierPathWithOvalInRect:r];
+                [ellipsePath setLineWidth:3];
+                [ellipsePath stroke];
+            }
+        }
+    }
+}
+
+- (NSString *)resizeHandleAtPoint:(NSPoint)p {
+    if (!_hasSelection) {
+        return nil;
+    }
+    CGFloat t = 9;
+    NSDictionary *handles = @{
+        @"nw": [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMinY(_selection))],
+        @"n": [NSValue valueWithPoint:NSMakePoint(NSMidX(_selection), NSMinY(_selection))],
+        @"ne": [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMinY(_selection))],
+        @"e": [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMidY(_selection))],
+        @"se": [NSValue valueWithPoint:NSMakePoint(NSMaxX(_selection), NSMaxY(_selection))],
+        @"s": [NSValue valueWithPoint:NSMakePoint(NSMidX(_selection), NSMaxY(_selection))],
+        @"sw": [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMaxY(_selection))],
+        @"w": [NSValue valueWithPoint:NSMakePoint(NSMinX(_selection), NSMidY(_selection))]
+    };
+    for (NSString *key in handles) {
+        NSPoint hp = [handles[key] pointValue];
+        if (fabs(p.x - hp.x) <= t && fabs(p.y - hp.y) <= t) {
+            return key;
+        }
+    }
+    BOOL nearX = p.x >= NSMinX(_selection) - t && p.x <= NSMaxX(_selection) + t;
+    BOOL nearY = p.y >= NSMinY(_selection) - t && p.y <= NSMaxY(_selection) + t;
+    if (nearX && fabs(p.y - NSMinY(_selection)) <= t) return @"n";
+    if (nearX && fabs(p.y - NSMaxY(_selection)) <= t) return @"s";
+    if (nearY && fabs(p.x - NSMinX(_selection)) <= t) return @"w";
+    if (nearY && fabs(p.x - NSMaxX(_selection)) <= t) return @"e";
+    return nil;
+}
+
+- (NSPoint)localPoint:(NSPoint)p {
+    return NSMakePoint(
+        MAX(0, MIN(p.x - _selection.origin.x, _selection.size.width)),
+        MAX(0, MIN(p.y - _selection.origin.y, _selection.size.height)));
+}
+
 - (void)mouseDown:(NSEvent *)event {
     NSPoint p = [self convertPoint:[event locationInWindow] fromView:nil];
-    if (_hasSelection && NSPointInRect(p, _selection)) {
+    NSString *handle = [self resizeHandleAtPoint:p];
+    if (handle != nil) {
+        _resizing = YES;
+        _creating = NO;
+        _moving = NO;
+        _annotating = NO;
+        _resizeHandle = handle;
+        _resizeStart = _selection;
+    } else if (_hasSelection && NSPointInRect(p, _selection) && _activeTool != nil) {
+        _annotating = YES;
+        _creating = NO;
+        _moving = NO;
+        _resizing = NO;
+        NSPoint local = [self localPoint:p];
+        _draftAnnotation = [@{
+            @"tool": _activeTool,
+            @"color": [self hexForColor:_activeColor],
+            @"nsColor": _activeColor,
+            @"points": [NSMutableArray arrayWithObject:[NSValue valueWithPoint:local]]
+        } mutableCopy];
+    } else if (_hasSelection && NSPointInRect(p, _selection)) {
         _moving = YES;
         _creating = NO;
+        _resizing = NO;
+        _annotating = NO;
         _moveOffset = NSMakePoint(p.x - _selection.origin.x, p.y - _selection.origin.y);
     } else {
         _creating = YES;
         _moving = NO;
+        _resizing = NO;
+        _annotating = NO;
         _hasSelection = YES;
         _anchor = p;
         _selection = NSMakeRect(p.x, p.y, 0, 0);
+        [_annotations removeAllObjects];
+        _draftAnnotation = nil;
     }
     [self syncControls];
 }
@@ -166,6 +362,32 @@ static id nativeOverlayKeyMonitor = nil;
         x = MAX(0, MIN(x, self.bounds.size.width - _selection.size.width));
         y = MAX(0, MIN(y, self.bounds.size.height - _selection.size.height));
         _selection.origin = NSMakePoint(x, y);
+    } else if (_resizing) {
+        CGFloat left = NSMinX(_resizeStart);
+        CGFloat top = NSMinY(_resizeStart);
+        CGFloat right = NSMaxX(_resizeStart);
+        CGFloat bottom = NSMaxY(_resizeStart);
+        if ([_resizeHandle containsString:@"w"]) left = p.x;
+        if ([_resizeHandle containsString:@"e"]) right = p.x;
+        if ([_resizeHandle containsString:@"n"]) top = p.y;
+        if ([_resizeHandle containsString:@"s"]) bottom = p.y;
+        left = MAX(0, MIN(left, self.bounds.size.width));
+        right = MAX(0, MIN(right, self.bounds.size.width));
+        top = MAX(0, MIN(top, self.bounds.size.height));
+        bottom = MAX(0, MIN(bottom, self.bounds.size.height));
+        _selection = NSMakeRect(MIN(left, right), MIN(top, bottom), fabs(right - left), fabs(bottom - top));
+    } else if (_annotating && _draftAnnotation != nil) {
+        NSMutableArray *points = _draftAnnotation[@"points"];
+        NSPoint local = [self localPoint:p];
+        if ([_activeTool isEqualToString:@"pen"]) {
+            [points addObject:[NSValue valueWithPoint:local]];
+        } else {
+            if (points.count == 1) {
+                [points addObject:[NSValue valueWithPoint:local]];
+            } else {
+                points[1] = [NSValue valueWithPoint:local];
+            }
+        }
     }
     [self syncControls];
     [self setNeedsDisplay:YES];
@@ -174,6 +396,12 @@ static id nativeOverlayKeyMonitor = nil;
 - (void)mouseUp:(NSEvent *)event {
     _creating = NO;
     _moving = NO;
+    _resizing = NO;
+    if (_annotating && _draftAnnotation != nil) {
+        [_annotations addObject:_draftAnnotation];
+        _draftAnnotation = nil;
+    }
+    _annotating = NO;
     if (_hasSelection && (_selection.size.width < 4 || _selection.size.height < 4)) {
         _hasSelection = NO;
     }
@@ -199,6 +427,11 @@ static id nativeOverlayKeyMonitor = nil;
     BOOL visible = _hasSelection && _selection.size.width >= 4 && _selection.size.height >= 4;
     [_cancelButton setHidden:!visible];
     [_uploadButton setHidden:!visible];
+    [_penButton setHidden:!visible];
+    [_rectButton setHidden:!visible];
+    [_ellipseButton setHidden:!visible];
+    [_colorButton setHidden:!visible];
+    [_undoButton setHidden:!visible];
     [_sizeLabel setHidden:!visible];
     [_hintLabel setHidden:_hasSelection];
 
@@ -220,6 +453,98 @@ static id nativeOverlayKeyMonitor = nil;
 
     [_cancelButton setFrame:NSMakeRect(x, y, 86, 32)];
     [_uploadButton setFrame:NSMakeRect(x + 92, y, 128, 32)];
+
+    CGFloat markW = 170;
+    CGFloat markX = MAX(0, MIN(_selection.origin.x, self.bounds.size.width - markW));
+    [_penButton setFrame:NSMakeRect(markX + 4, y + 4, 28, 28)];
+    [_rectButton setFrame:NSMakeRect(markX + 36, y + 4, 28, 28)];
+    [_ellipseButton setFrame:NSMakeRect(markX + 68, y + 4, 28, 28)];
+    [_colorButton setFrame:NSMakeRect(markX + 104, y + 7, 22, 22)];
+    [_undoButton setFrame:NSMakeRect(markX + 134, y + 4, 28, 28)];
+    [[_colorButton layer] setBackgroundColor:[_activeColor CGColor]];
+    [_undoButton setEnabled:_annotations.count > 0];
+    [_paletteView setFrame:NSMakeRect(markX, MAX(0, y - 78), 150, 70)];
+    [self updateToolButtonStates];
+}
+
+- (void)updateToolButtonStates {
+    NSDictionary *buttons = @{@"pen": _penButton, @"rect": _rectButton, @"ellipse": _ellipseButton};
+    for (NSString *tool in buttons) {
+        NSButton *button = buttons[tool];
+        NSColor *bg = [tool isEqualToString:_activeTool]
+            ? [NSColor colorWithCalibratedWhite:1.0 alpha:0.14]
+            : [NSColor clearColor];
+        [[button layer] setBackgroundColor:[bg CGColor]];
+    }
+}
+
+- (void)toggleTool:(NSString *)tool {
+    _activeTool = [_activeTool isEqualToString:tool] ? nil : tool;
+    [self syncControls];
+}
+- (void)selectPen { [self toggleTool:@"pen"]; }
+- (void)selectRect { [self toggleTool:@"rect"]; }
+- (void)selectEllipse { [self toggleTool:@"ellipse"]; }
+- (void)undoAnnotation {
+    if (_annotations.count > 0) {
+        [_annotations removeLastObject];
+        [self syncControls];
+        [self setNeedsDisplay:YES];
+    }
+}
+
+- (void)togglePalette {
+    [_paletteView setHidden:![_paletteView isHidden]];
+    if (![_paletteView isHidden] && _paletteView.subviews.count == 0) {
+        NSArray *colors = @[
+            [NSColor colorWithCalibratedRed:239.0/255.0 green:68.0/255.0 blue:68.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:249.0/255.0 green:115.0/255.0 blue:22.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:250.0/255.0 green:204.0/255.0 blue:21.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:34.0/255.0 green:197.0/255.0 blue:94.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:59.0/255.0 green:130.0/255.0 blue:246.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:139.0/255.0 green:92.0/255.0 blue:246.0/255.0 alpha:1.0],
+            [NSColor colorWithCalibratedRed:236.0/255.0 green:72.0/255.0 blue:153.0/255.0 alpha:1.0],
+            [NSColor whiteColor],
+            [NSColor colorWithCalibratedWhite:0.07 alpha:1.0]
+        ];
+        for (NSUInteger i = 0; i < colors.count; i++) {
+            NSButton *button = [NSButton buttonWithTitle:@"" target:self action:@selector(selectPaletteColor:)];
+            [button setBordered:NO];
+            [button setWantsLayer:YES];
+            [[button layer] setCornerRadius:4];
+            [[button layer] setBackgroundColor:[colors[i] CGColor]];
+            [button setTag:(NSInteger)i];
+            [button setFrame:NSMakeRect(8 + (i % 5) * 28, 38 - (i / 5) * 28, 22, 22)];
+            [_paletteView addSubview:button];
+        }
+        objc_setAssociatedObject(_paletteView, "snapgoColors", colors, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+    }
+}
+
+- (void)selectPaletteColor:(NSButton *)sender {
+    NSArray *colors = objc_getAssociatedObject(_paletteView, "snapgoColors");
+    if (sender.tag >= 0 && sender.tag < (NSInteger)colors.count) {
+        _activeColor = colors[(NSUInteger)sender.tag];
+        [_paletteView setHidden:YES];
+        [self syncControls];
+    }
+}
+
+- (NSString *)annotationsJSON {
+    NSMutableArray *payload = [NSMutableArray array];
+    for (NSDictionary *item in _annotations) {
+        NSMutableArray *points = [NSMutableArray array];
+        for (NSValue *value in item[@"points"]) {
+            NSPoint p = [value pointValue];
+            [points addObject:@{@"x": @(p.x), @"y": @(p.y)}];
+        }
+        [payload addObject:@{@"tool": item[@"tool"], @"color": item[@"color"], @"points": points}];
+    }
+    NSData *data = [NSJSONSerialization dataWithJSONObject:payload options:0 error:nil];
+    if (data == nil) {
+        return @"[]";
+    }
+    return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
 }
 
 - (void)confirmSelection {
@@ -233,7 +558,8 @@ static id nativeOverlayKeyMonitor = nil;
             nativeOverlayKeyMonitor = nil;
         }
     nativeOverlayWindow = nil;
-    nativeOverlayConfirm((int)llround(r.origin.x), (int)llround(r.origin.y), (int)llround(r.size.width), (int)llround(r.size.height));
+    NSString *json = [self annotationsJSON];
+    nativeOverlayConfirm((int)llround(r.origin.x), (int)llround(r.origin.y), (int)llround(r.size.width), (int)llround(r.size.height), [json UTF8String]);
 }
 
 - (void)cancelSelection {