diff --git a/apps/desktop/scripts/diag-overlay-churn.mjs b/apps/desktop/scripts/diag-overlay-churn.mjs
new file mode 100644
index 00000000000..41a2379093f
--- /dev/null
+++ b/apps/desktop/scripts/diag-overlay-churn.mjs
@@ -0,0 +1,161 @@
+#!/usr/bin/env node
+// CDP probe: measure render churn on overlay surfaces (cmdk, settings, command-center, skills)
+// against the user's live instance on :9222. Read-only — never closes or navigates away.
+import WebSocket from 'ws'
+
+const CDP_URL = 'ws://127.0.0.1:9222'
+const TARGET_GLOB = '/devtools/page/'
+
+let msgId = 1
+
+function send(ws, method, params = {}) {
+  const id = msgId++
+  return new Promise((resolve, reject) => {
+    const handler = (data) => {
+      const msg = JSON.parse(data.toString())
+      if (msg.id === id) {
+        ws.off('message', handler)
+        if (msg.error) reject(new Error(JSON.stringify(msg.error)))
+        else resolve(msg.result)
+      }
+    }
+    ws.on('message', handler)
+    ws.send(JSON.stringify({ id, method, params }))
+  })
+}
+
+async function getRendererTarget() {
+  const resp = await fetch('http://127.0.0.1:9222/json/list')
+  const targets = await resp.json()
+  // Find the renderer target (not devtools)
+  return targets.find(t => t.url?.startsWith('http://127.0.0.1:5174') || t.url?.includes('5174'))
+    ?? targets.find(t => t.type === 'page' && !t.url.startsWith('devtools'))
+}
+
+async function evalInPage(ws, expr) {
+  const result = await send(ws, 'Runtime.evaluate', {
+    expression: expr,
+    returnByValue: true,
+    awaitPromise: true,
+  })
+  return result?.result?.value
+}
+
+async function main() {
+  const target = await getRendererTarget()
+  if (!target) {
+    console.error('No renderer target found')
+    process.exit(1)
+  }
+  console.log(`Target: ${target.url}`)
+
+  const ws = new WebSocket(target.webSocketDebuggerUrl)
+  await new Promise((resolve, reject) => {
+    ws.on('open', resolve)
+    ws.on('error', reject)
+  })
+
+  await send(ws, 'Runtime.enable')
+
+  // Check if __RENDER_COUNTS__ is available
+  const hasCounter = await evalInPage(ws, 'typeof __RENDER_COUNTS__')
+  console.log(`__RENDER_COUNTS__ available: ${hasCounter}`)
+
+  if (hasCounter !== 'object') {
+    console.log('Render counter not loaded — checking perf-live...')
+    const hasPerfLive = await evalInPage(ws, 'typeof __PERF_LIVE__')
+    console.log(`__PERF_LIVE__ available: ${hasPerfLive}`)
+  }
+
+  // 1. Baseline: open cmdk, type a few chars, measure
+  console.log('\n=== CmdK Palette ===')
+  await evalInPage(ws, `
+    window.__renderBaseline = {}
+    if (typeof __RENDER_COUNTS__ === 'object' && __RENDER_COUNTS__) {
+      __RENDER_COUNTS__.reset()
+    }
+    // Open cmdk via keyboard shortcut
+    const evt = new KeyboardEvent('keydown', { key: 'k', metaKey: true, bubbles: true })
+    document.dispatchEvent(evt)
+    true
+  `)
+  await new Promise(r => setTimeout(r, 500))
+
+  // Type some characters
+  for (const ch of ['s', 'e', 't', 't', 'i', 'n', 'g']) {
+    await evalInPage(ws, `
+      const el = document.querySelector('[cmdk-input]') || document.querySelector('input[placeholder]')
+      if (el) {
+        el.focus()
+        el.value = el.value + '${ch}'
+        el.dispatchEvent(new Event('input', { bubbles: true }))
+      }
+      true
+    `)
+    await new Promise(r => setTimeout(r, 80))
+  }
+
+  await new Promise(r => setTimeout(r, 300))
+  const cmdkCounts = await evalInPage(ws, `
+    __RENDER_COUNTS__?.snapshot?.() ?? __RENDER_COUNTS__?.counts ?? 'no counter'
+  `)
+  console.log('CmdK render counts after typing "setting":', JSON.stringify(cmdkCounts, null, 2))
+
+  // Close cmdk
+  await evalInPage(ws, `new KeyboardEvent('keydown', { key: 'Escape', bubbles: true }); document.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape', bubbles: true })); true`)
+  await new Promise(r => setTimeout(r, 300))
+
+  // 2. Command Center — measure renders while on System tab
+  console.log('\n=== Command Center (System tab) ===')
+  await evalInPage(ws, `
+    if (typeof __RENDER_COUNTS__ === 'object' && __RENDER_COUNTS__) {
+      __RENDER_COUNTS__.reset()
+    }
+    // Navigate to command center system section
+    const link = Array.from(document.querySelectorAll('a, button')).find(el => el.textContent?.includes('System') || el.textContent?.includes('Command Center'))
+    if (link) link.click()
+    true
+  `)
+  await new Promise(r => setTimeout(r, 1000))
+
+  const ccCounts = await evalInPage(ws, `
+    __RENDER_COUNTS__?.snapshot?.() ?? __RENDER_COUNTS__?.counts ?? 'no counter'
+  `)
+  console.log('Command Center render counts (after 1s on System tab):', JSON.stringify(ccCounts, null, 2))
+
+  // 3. Settings page — measure renders on nav
+  console.log('\n=== Settings Page ===')
+  await evalInPage(ws, `
+    if (typeof __RENDER_COUNTS__ === 'object' && __RENDER_COUNTS__) {
+      __RENDER_COUNTS__.reset()
+    }
+    // Navigate to settings
+    const link = Array.from(document.querySelectorAll('a, button')).find(el => el.textContent?.includes('Settings'))
+    if (link) link.click()
+    true
+  `)
+  await new Promise(r => setTimeout(r, 1000))
+
+  // Click through a few nav items
+  for (const label of ['Appearance', 'Gateway', 'Keys', 'About']) {
+    await evalInPage(ws, `
+      const el = Array.from(document.querySelectorAll('button')).find(b => b.textContent?.trim() === '${label}')
+      if (el) el.click()
+      true
+    `)
+    await new Promise(r => setTimeout(r, 150))
+  }
+
+  const settingsCounts = await evalInPage(ws, `
+    __RENDER_COUNTS__?.snapshot?.() ?? __RENDER_COUNTS__?.counts ?? 'no counter'
+  `)
+  console.log('Settings render counts (after clicking 4 nav items):', JSON.stringify(settingsCounts, null, 2))
+
+  ws.close()
+  console.log('\nDone.')
+}
+
+main().catch(err => {
+  console.error('Error:', err)
+  process.exit(1)
+})