diff --git a/packages/app/src/utils/desktop-window-drag-coordinates.test.ts b/packages/app/src/utils/desktop-window-drag-coordinates.test.ts
new file mode 100644
index 000000000..3f21e147c
--- /dev/null
+++ b/packages/app/src/utils/desktop-window-drag-coordinates.test.ts
@@ -0,0 +1,28 @@
+import { describe, expect, it } from 'vitest'
+
+import { readFiniteScreenPoint } from './desktop-window-drag-coordinates'
+
+describe('readFiniteScreenPoint', () => {
+  it('returns finite screen coordinates', () => {
+    expect(readFiniteScreenPoint({ screenX: 1280, screenY: 720 })).toEqual({
+      screenX: 1280,
+      screenY: 720,
+    })
+  })
+
+  it('rejects NaN screen coordinates', () => {
+    expect(readFiniteScreenPoint({ screenX: Number.NaN, screenY: 720 })).toBeNull()
+    expect(readFiniteScreenPoint({ screenX: 1280, screenY: Number.NaN })).toBeNull()
+  })
+
+  it('rejects infinite screen coordinates', () => {
+    expect(readFiniteScreenPoint({ screenX: Number.POSITIVE_INFINITY, screenY: 720 })).toBeNull()
+    expect(readFiniteScreenPoint({ screenX: 1280, screenY: Number.NEGATIVE_INFINITY })).toBeNull()
+  })
+
+  it('rejects missing screen coordinates', () => {
+    expect(readFiniteScreenPoint(undefined)).toBeNull()
+    expect(readFiniteScreenPoint({ screenX: 1280 })).toBeNull()
+    expect(readFiniteScreenPoint({ screenY: 720 })).toBeNull()
+  })
+})
diff --git a/packages/app/src/utils/desktop-window-drag-coordinates.ts b/packages/app/src/utils/desktop-window-drag-coordinates.ts
new file mode 100644
index 000000000..f5db90caf
--- /dev/null
+++ b/packages/app/src/utils/desktop-window-drag-coordinates.ts
@@ -0,0 +1,27 @@
+export type DesktopWindowScreenPoint = {
+  screenX: number
+  screenY: number
+}
+
+type ScreenPointInput =
+  | {
+      screenX?: unknown
+      screenY?: unknown
+    }
+  | null
+  | undefined
+
+function isFiniteCoordinate(value: unknown): value is number {
+  return typeof value === 'number' && Number.isFinite(value)
+}
+
+export function readFiniteScreenPoint(input: ScreenPointInput): DesktopWindowScreenPoint | null {
+  if (!isFiniteCoordinate(input?.screenX) || !isFiniteCoordinate(input?.screenY)) {
+    return null
+  }
+
+  return {
+    screenX: input.screenX,
+    screenY: input.screenY,
+  }
+}
diff --git a/packages/app/src/utils/desktop-window.ts b/packages/app/src/utils/desktop-window.ts
index e27898b0f..468d5e5b7 100644
--- a/packages/app/src/utils/desktop-window.ts
+++ b/packages/app/src/utils/desktop-window.ts
@@ -1,20 +1,21 @@
-import { useEffect, useMemo, useRef, useState } from "react";
-import { Platform, type PointerEvent as RNPointerEvent, type ViewProps } from "react-native";
+import { useEffect, useMemo, useRef, useState } from 'react'
+import { Platform, type PointerEvent as RNPointerEvent, type ViewProps } from 'react-native'
 import {
   getIsDesktopMac,
   DESKTOP_TRAFFIC_LIGHT_WIDTH,
   DESKTOP_TRAFFIC_LIGHT_HEIGHT,
-} from "@/constants/layout";
-import { getDesktopWindow } from "@/desktop/electron/window";
-import { isDesktop } from "@/desktop/host";
+} from '@/constants/layout'
+import { getDesktopWindow } from '@/desktop/electron/window'
+import { isDesktop } from '@/desktop/host'
+import { readFiniteScreenPoint } from './desktop-window-drag-coordinates'
 
 export async function toggleMaximize() {
-  const win = getDesktopWindow();
-  if (win && typeof win.toggleMaximize === "function") {
+  const win = getDesktopWindow()
+  if (win && typeof win.toggleMaximize === 'function') {
     try {
-      await win.toggleMaximize();
+      await win.toggleMaximize()
     } catch (error) {
-      console.warn("[DesktopWindow] toggleMaximize failed", error);
+      console.warn('[DesktopWindow] toggleMaximize failed', error)
     }
   }
 }
@@ -27,147 +28,152 @@ export async function toggleMaximize() {
 // ---------------------------------------------------------------------------
 
 const INTERACTIVE_SELECTOR =
-  "button, a, input, textarea, select, " +
+  'button, a, input, textarea, select, ' +
   "[role='button'], [role='link'], [role='textbox'], [role='combobox'], " +
   "[role='tab'], [role='switch'], [role='checkbox'], [role='slider'], " +
-  "[role='menuitem'], [contenteditable='true']";
+  "[role='menuitem'], [contenteditable='true']"
 
-const DOUBLE_CLICK_MS = 300;
+const DOUBLE_CLICK_MS = 300
 
 type DesktopDragViewProps = Pick<
   ViewProps,
-  "onPointerDown" | "onPointerMove" | "onPointerUp" | "onPointerCancel"
->;
+  'onPointerDown' | 'onPointerMove' | 'onPointerUp' | 'onPointerCancel'
+>
 
 export function useDesktopDragHandlers(): DesktopDragViewProps {
-  const isDragging = useRef(false);
-  const lastPointerDownAt = useRef(0);
-  const isActive = Platform.OS === "web" && isDesktop();
+  const isDragging = useRef(false)
+  const lastPointerDownAt = useRef(0)
+  const isActive = Platform.OS === 'web' && isDesktop()
 
   useEffect(() => {
-    if (!isActive) return;
+    if (!isActive) return
     function handleBlur() {
-      if (!isDragging.current) return;
-      isDragging.current = false;
-      getDesktopWindow()?.endMove?.();
+      if (!isDragging.current) return
+      isDragging.current = false
+      getDesktopWindow()?.endMove?.()
     }
-    window.addEventListener("blur", handleBlur);
-    return () => window.removeEventListener("blur", handleBlur);
-  }, [isActive]);
+    window.addEventListener('blur', handleBlur)
+    return () => window.removeEventListener('blur', handleBlur)
+  }, [isActive])
 
   return useMemo((): DesktopDragViewProps => {
-    if (!isActive) return {};
+    if (!isActive) return {}
 
     function stopDrag(e: RNPointerEvent) {
-      if (!isDragging.current) return;
-      isDragging.current = false;
+      if (!isDragging.current) return
+      isDragging.current = false
       // On web, currentTarget is a DOM Element (typed as HostInstance in RN)
-      const el = e.currentTarget as unknown as Element | null;
-      if (el && "releasePointerCapture" in el) {
-        el.releasePointerCapture(e.nativeEvent.pointerId);
+      const el = e.currentTarget as unknown as Element | null
+      if (el && 'releasePointerCapture' in el) {
+        el.releasePointerCapture(e.nativeEvent.pointerId)
       }
-      getDesktopWindow()?.endMove?.();
+      getDesktopWindow()?.endMove?.()
     }
 
     return {
       onPointerDown: (e: RNPointerEvent) => {
-        if (e.nativeEvent.button !== 0) return;
+        if (e.nativeEvent.button !== 0) return
 
         // On web, e.target is a DOM Element (typed as HostInstance in RN)
-        const target = e.target as unknown as Element;
-        if (target.closest?.(INTERACTIVE_SELECTOR)) return;
+        const target = e.target as unknown as Element
+        if (target.closest?.(INTERACTIVE_SELECTOR)) return
 
-        e.preventDefault();
+        e.preventDefault()
 
-        const now = Date.now();
+        const now = Date.now()
         if (now - lastPointerDownAt.current < DOUBLE_CLICK_MS) {
-          lastPointerDownAt.current = 0;
-          void toggleMaximize();
-          return;
+          lastPointerDownAt.current = 0
+          void toggleMaximize()
+          return
         }
-        lastPointerDownAt.current = now;
+        lastPointerDownAt.current = now
 
-        const win = getDesktopWindow();
-        if (!win?.startMove) return;
+        const win = getDesktopWindow()
+        if (!win?.startMove) return
+        const screenPoint = readFiniteScreenPoint(e.nativeEvent)
+        if (!screenPoint) return
 
-        isDragging.current = true;
-        const el = e.currentTarget as unknown as Element;
-        el.setPointerCapture(e.nativeEvent.pointerId);
-        win.startMove(e.nativeEvent.screenX, e.nativeEvent.screenY);
+        isDragging.current = true
+        const el = e.currentTarget as unknown as Element
+        el.setPointerCapture(e.nativeEvent.pointerId)
+        win.startMove(screenPoint.screenX, screenPoint.screenY)
       },
       onPointerMove: (e: RNPointerEvent) => {
-        if (!isDragging.current) return;
-        getDesktopWindow()?.moving?.(e.nativeEvent.screenX, e.nativeEvent.screenY);
+        if (!isDragging.current) return
+        const screenPoint = readFiniteScreenPoint(e.nativeEvent)
+        if (!screenPoint) {
+          stopDrag(e)
+          return
+        }
+        getDesktopWindow()?.moving?.(screenPoint.screenX, screenPoint.screenY)
       },
       onPointerUp: stopDrag,
       onPointerCancel: stopDrag,
-    };
-  }, [isActive]);
+    }
+  }, [isActive])
 }
 
 export function useTrafficLightPadding(): { left: number; top: number } {
-  const [isFullscreen, setIsFullscreen] = useState(false);
+  const [isFullscreen, setIsFullscreen] = useState(false)
 
   useEffect(() => {
-    if (Platform.OS !== "web" || !getIsDesktopMac()) return;
+    if (Platform.OS !== 'web' || !getIsDesktopMac()) return
 
-    let disposed = false;
-    let cleanup: (() => void) | undefined;
-    let didCleanup = false;
+    let disposed = false
+    let cleanup: (() => void) | undefined
+    let didCleanup = false
 
     function runCleanup() {
-      if (!cleanup || didCleanup) return;
-      didCleanup = true;
+      if (!cleanup || didCleanup) return
+      didCleanup = true
       try {
         void Promise.resolve(cleanup()).catch((error) => {
-          console.warn("[DesktopWindow] Failed to remove resize listener", error);
-        });
+          console.warn('[DesktopWindow] Failed to remove resize listener', error)
+        })
       } catch (error) {
-        console.warn("[DesktopWindow] Failed to remove resize listener", error);
+        console.warn('[DesktopWindow] Failed to remove resize listener', error)
       }
     }
 
     async function setup() {
-      const win = getDesktopWindow();
-      if (!win) return;
+      const win = getDesktopWindow()
+      if (!win) return
 
-      const fullscreen =
-        typeof win.isFullscreen === "function" ? await win.isFullscreen() : false;
-      if (disposed) return;
-      setIsFullscreen(fullscreen);
+      const fullscreen = typeof win.isFullscreen === 'function' ? await win.isFullscreen() : false
+      if (disposed) return
+      setIsFullscreen(fullscreen)
 
-      if (typeof win.onResized !== "function") {
-        return;
+      if (typeof win.onResized !== 'function') {
+        return
       }
 
       const unlisten = await win.onResized(async () => {
-        if (disposed) return;
-        const fs =
-          typeof win.isFullscreen === "function" ? await win.isFullscreen() : false;
-        if (disposed) return;
-        setIsFullscreen(fs);
-      });
+        if (disposed) return
+        const fs = typeof win.isFullscreen === 'function' ? await win.isFullscreen() : false
+        if (disposed) return
+        setIsFullscreen(fs)
+      })
 
-      cleanup = unlisten;
+      cleanup = unlisten
       if (disposed) {
-        runCleanup();
+        runCleanup()
       }
     }
 
-    void setup();
+    void setup()
 
     return () => {
-      disposed = true;
-      runCleanup();
-    };
-  }, []);
+      disposed = true
+      runCleanup()
+    }
+  }, [])
 
   if (!getIsDesktopMac() || isFullscreen) {
-    return { left: 0, top: 0 };
+    return { left: 0, top: 0 }
   }
 
   return {
     left: DESKTOP_TRAFFIC_LIGHT_WIDTH,
     top: DESKTOP_TRAFFIC_LIGHT_HEIGHT,
-  };
+  }
 }
diff --git a/packages/desktop/src/window/window-drag-coordinates.test.ts b/packages/desktop/src/window/window-drag-coordinates.test.ts
new file mode 100644
index 000000000..78e3c53ab
--- /dev/null
+++ b/packages/desktop/src/window/window-drag-coordinates.test.ts
@@ -0,0 +1,71 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+  createWindowMoveState,
+  readWindowMovePayload,
+  resolveWindowMovePosition,
+} from './window-drag-coordinates'
+
+describe('window-drag-coordinates', () => {
+  describe('readWindowMovePayload', () => {
+    it('returns finite screen coordinates', () => {
+      expect(readWindowMovePayload({ screenX: 1500, screenY: 900 })).toEqual({
+        screenX: 1500,
+        screenY: 900,
+      })
+    })
+
+    it('rejects non-finite screen coordinates', () => {
+      expect(readWindowMovePayload({ screenX: Number.NaN, screenY: 900 })).toBeNull()
+      expect(readWindowMovePayload({ screenX: 1500, screenY: Number.POSITIVE_INFINITY })).toBeNull()
+    })
+  })
+
+  describe('createWindowMoveState', () => {
+    it('derives finite offsets from the window position', () => {
+      expect(
+        createWindowMoveState({
+          payload: { screenX: 1500, screenY: 900 },
+          windowX: 1200,
+          windowY: 700,
+        })
+      ).toEqual({
+        offsetX: 300,
+        offsetY: 200,
+      })
+    })
+
+    it('rejects non-finite offsets', () => {
+      expect(
+        createWindowMoveState({
+          payload: { screenX: 1500, screenY: 900 },
+          windowX: Number.NaN,
+          windowY: 700,
+        })
+      ).toBeNull()
+    })
+  })
+
+  describe('resolveWindowMovePosition', () => {
+    it('rounds the next window position', () => {
+      expect(
+        resolveWindowMovePosition({
+          payload: { screenX: 1501.4, screenY: 902.6 },
+          state: { offsetX: 300, offsetY: 200 },
+        })
+      ).toEqual({
+        x: 1201,
+        y: 703,
+      })
+    })
+
+    it('rejects non-finite next positions', () => {
+      expect(
+        resolveWindowMovePosition({
+          payload: { screenX: 1500, screenY: 900 },
+          state: { offsetX: Number.NaN, offsetY: 200 },
+        })
+      ).toBeNull()
+    })
+  })
+})
diff --git a/packages/desktop/src/window/window-drag-coordinates.ts b/packages/desktop/src/window/window-drag-coordinates.ts
new file mode 100644
index 000000000..a2e4a612a
--- /dev/null
+++ b/packages/desktop/src/window/window-drag-coordinates.ts
@@ -0,0 +1,64 @@
+export type WindowMovePayload = {
+  screenX: number
+  screenY: number
+}
+
+export type WindowMoveState = {
+  offsetX: number
+  offsetY: number
+}
+
+export type WindowPosition = {
+  x: number
+  y: number
+}
+
+type WindowMovePayloadInput =
+  | {
+      screenX?: unknown
+      screenY?: unknown
+    }
+  | null
+  | undefined
+
+function isFiniteCoordinate(value: unknown): value is number {
+  return typeof value === 'number' && Number.isFinite(value)
+}
+
+export function readWindowMovePayload(input: WindowMovePayloadInput): WindowMovePayload | null {
+  if (!isFiniteCoordinate(input?.screenX) || !isFiniteCoordinate(input?.screenY)) {
+    return null
+  }
+
+  return {
+    screenX: input.screenX,
+    screenY: input.screenY,
+  }
+}
+
+export function createWindowMoveState(input: {
+  payload: WindowMovePayload
+  windowX: number
+  windowY: number
+}): WindowMoveState | null {
+  const offsetX = input.payload.screenX - input.windowX
+  const offsetY = input.payload.screenY - input.windowY
+  if (!Number.isFinite(offsetX) || !Number.isFinite(offsetY)) {
+    return null
+  }
+
+  return { offsetX, offsetY }
+}
+
+export function resolveWindowMovePosition(input: {
+  payload: WindowMovePayload
+  state: WindowMoveState
+}): WindowPosition | null {
+  const x = Math.round(input.payload.screenX - input.state.offsetX)
+  const y = Math.round(input.payload.screenY - input.state.offsetY)
+  if (!Number.isFinite(x) || !Number.isFinite(y)) {
+    return null
+  }
+
+  return { x, y }
+}
diff --git a/packages/desktop/src/window/window-manager.ts b/packages/desktop/src/window/window-manager.ts
index 511ac0f3b..747366352 100644
--- a/packages/desktop/src/window/window-manager.ts
+++ b/packages/desktop/src/window/window-manager.ts
@@ -1,81 +1,103 @@
-import { app, BrowserWindow, ipcMain } from "electron";
+import { app, BrowserWindow, ipcMain } from 'electron'
+import {
+  createWindowMoveState,
+  readWindowMovePayload,
+  resolveWindowMovePosition,
+  type WindowMoveState,
+} from './window-drag-coordinates.js'
 
 export function registerWindowManager(): void {
   // ---------------------------------------------------------------------------
   // Manual window dragging (replaces flaky CSS -webkit-app-region: drag).
   // State is keyed per window id to support multiple windows.
   // ---------------------------------------------------------------------------
-  const moveStates = new Map<number, { offsetX: number; offsetY: number }>();
+  const moveStates = new Map<number, WindowMoveState>()
 
-  ipcMain.on(
-    "paseo:window:startMove",
-    (event, payload: { screenX: number; screenY: number }) => {
-      if (typeof payload?.screenX !== "number" || typeof payload?.screenY !== "number") return;
-      const win = BrowserWindow.fromWebContents(event.sender);
-      if (!win) return;
-      const [winX, winY] = win.getPosition();
-      moveStates.set(win.id, { offsetX: payload.screenX - winX, offsetY: payload.screenY - winY });
+  ipcMain.on('paseo:window:startMove', (event, payload: { screenX: number; screenY: number }) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    if (!win) return
+    const movePayload = readWindowMovePayload(payload)
+    if (!movePayload) {
+      moveStates.delete(win.id)
+      return
     }
-  );
-
-  ipcMain.on(
-    "paseo:window:moving",
-    (event, payload: { screenX: number; screenY: number }) => {
-      if (typeof payload?.screenX !== "number" || typeof payload?.screenY !== "number") return;
-      const win = BrowserWindow.fromWebContents(event.sender);
-      if (!win) return;
-      const state = moveStates.get(win.id);
-      if (!state) return;
-      win.setPosition(
-        Math.round(payload.screenX - state.offsetX),
-        Math.round(payload.screenY - state.offsetY)
-      );
+    const [winX, winY] = win.getPosition()
+    const moveState = createWindowMoveState({
+      payload: movePayload,
+      windowX: winX,
+      windowY: winY,
+    })
+    if (!moveState) {
+      moveStates.delete(win.id)
+      return
     }
-  );
+    moveStates.set(win.id, moveState)
+  })
 
-  ipcMain.on("paseo:window:endMove", (event) => {
-    const win = BrowserWindow.fromWebContents(event.sender);
-    if (win) moveStates.delete(win.id);
-  });
+  ipcMain.on('paseo:window:moving', (event, payload: { screenX: number; screenY: number }) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    if (!win) return
+    const state = moveStates.get(win.id)
+    if (!state) return
+    const movePayload = readWindowMovePayload(payload)
+    if (!movePayload) {
+      moveStates.delete(win.id)
+      return
+    }
+    const nextPosition = resolveWindowMovePosition({
+      payload: movePayload,
+      state,
+    })
+    if (!nextPosition) {
+      moveStates.delete(win.id)
+      return
+    }
+    win.setPosition(nextPosition.x, nextPosition.y)
+  })
 
-  app.on("browser-window-created", (_event, win) => {
-    win.on("closed", () => moveStates.delete(win.id));
-  });
+  ipcMain.on('paseo:window:endMove', (event) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    if (win) moveStates.delete(win.id)
+  })
 
-  ipcMain.handle("paseo:window:toggleMaximize", (event) => {
-    const win = BrowserWindow.fromWebContents(event.sender);
-    if (!win) return;
+  app.on('browser-window-created', (_event, win) => {
+    win.on('closed', () => moveStates.delete(win.id))
+  })
+
+  ipcMain.handle('paseo:window:toggleMaximize', (event) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    if (!win) return
     if (win.isMaximized()) {
-      win.unmaximize();
+      win.unmaximize()
     } else {
-      win.maximize();
+      win.maximize()
     }
-  });
+  })
 
-  ipcMain.handle("paseo:window:isFullscreen", (event) => {
-    const win = BrowserWindow.fromWebContents(event.sender);
-    return win?.isFullScreen() ?? false;
-  });
+  ipcMain.handle('paseo:window:isFullscreen', (event) => {
+    const win = BrowserWindow.fromWebContents(event.sender)
+    return win?.isFullScreen() ?? false
+  })
 
-  ipcMain.handle("paseo:window:setBadgeCount", (_event, count?: number) => {
-    if (process.platform === "darwin" || process.platform === "linux") {
-      app.setBadgeCount(count ?? 0);
+  ipcMain.handle('paseo:window:setBadgeCount', (_event, count?: number) => {
+    if (process.platform === 'darwin' || process.platform === 'linux') {
+      app.setBadgeCount(count ?? 0)
     }
-  });
+  })
 }
 
 export function setupWindowResizeEvents(win: BrowserWindow): void {
-  win.on("resize", () => {
-    win.webContents.send("paseo:window:resized", {});
-  });
+  win.on('resize', () => {
+    win.webContents.send('paseo:window:resized', {})
+  })
 
-  win.on("enter-full-screen", () => {
-    win.webContents.send("paseo:window:resized", {});
-  });
+  win.on('enter-full-screen', () => {
+    win.webContents.send('paseo:window:resized', {})
+  })
 
-  win.on("leave-full-screen", () => {
-    win.webContents.send("paseo:window:resized", {});
-  });
+  win.on('leave-full-screen', () => {
+    win.webContents.send('paseo:window:resized', {})
+  })
 }
 
 /**
@@ -83,11 +105,11 @@ export function setupWindowResizeEvents(win: BrowserWindow): void {
  * The renderer handles drag-drop via standard HTML5 APIs instead.
  */
 export function setupDragDropPrevention(win: BrowserWindow): void {
-  win.webContents.on("will-navigate", (event, url) => {
+  win.webContents.on('will-navigate', (event, url) => {
     // Allow normal navigation (e.g. dev server hot-reload) but block file:// URLs
     // that result from dropping files onto the window.
-    if (url.startsWith("file://")) {
-      event.preventDefault();
+    if (url.startsWith('file://')) {
+      event.preventDefault()
     }
-  });
+  })
 }