diff --git a/knip.json b/knip.json
index 0901fcb18..d0702b9de 100644
--- a/knip.json
+++ b/knip.json
@@ -7,7 +7,8 @@
     "scripts/react/profiler.ts!",
     "scripts/react/boundaries.tsx!",
     "scripts/react/material.tsx!",
-    "scripts/react/yaml.ts!"
+    "scripts/react/yaml.ts!",
+    "scripts/react/wdyr.ts!"
   ],
   "project": ["src/**/*.{js,jsx,ts,tsx,sass,scss}!", "scripts/**/*.{js,mjs}!"],
   "include": [
diff --git a/package.json b/package.json
index 6efbdaa30..f79fb5dc8 100644
--- a/package.json
+++ b/package.json
@@ -42,7 +42,8 @@
     "perf:compare": "node scripts/perf/compare.mjs",
     "perf:test": "node --test scripts/perf/report.test.mjs",
     "dev:profile": "cross-env CVR_REACT_DIAGNOSTICS=profiler node scripts/dev.mjs dev",
-    "react:ab": "node scripts/react/ab.mjs"
+    "react:ab": "node scripts/react/ab.mjs",
+    "dev:wdyr": "cross-env CVR_REACT_DIAGNOSTICS=wdyr node scripts/dev.mjs dev"
   },
   "dependencies": {
     "@dnd-kit/collision": "^0.5.0",
@@ -137,7 +138,8 @@
     "vitest": "^5.0.1",
     "webdriverio": "10.1.0",
     "ws": "8.22.1",
-    "playwright": "1.64.1"
+    "playwright": "1.64.1",
+    "@welldone-software/why-did-you-render": "10.0.1"
   },
   "lint-staged": {
     "*.{ts,tsx,js,mjs}": [
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 96a9d3e73..a15dcf9aa 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -341,6 +341,9 @@ importers:
       '@wdio/tauri-service':
         specifier: 1.5.0
         version: 1.5.0(expect-webdriverio@6.1.0)(supports-color@7.2.0)(webdriverio@10.1.0(supports-color@7.2.0)(yauzl@2.10.0))
+      '@welldone-software/why-did-you-render':
+        specifier: 10.0.1
+        version: 10.0.1(react@19.3.1)
       adm-zip:
         specifier: ^0.6.1
         version: 0.6.1
@@ -2681,6 +2684,11 @@ packages:
     resolution: {integrity: sha512-BABJY+L4JidOD2bfQe3icuRZ0jQeUimTwUEe66I4BHVGWwaa5QBeVU+JZmdNQLjMA9q+Nk385aL96Mb1/PbKYw==}
     engines: {node: '>=22.19.0'}
 
+  '@welldone-software/why-did-you-render@10.0.1':
+    resolution: {integrity: sha512-tMgGkt30iVYeLMUKExNmtm019QgyjLtA7lwB0QAizYNEuihlCG2eoAWBBaz/bDeI7LeqAJ9msC6hY3vX+JB97g==}
+    peerDependencies:
+      react: ^19
+
   '@zip.js/zip.js@2.24.0':
     resolution: {integrity: sha512-WlaVKzdqBK+RF3bdiXZWbdCnvGB6PdO4IHC1mn/2Yfl3bASgqUNegnU3+PNg61iecwoPfUi5BgLUPqBukXpyWw==}
     engines: {bun: '>=0.7.0', deno: '>=1.0.0', node: '>=18.0.0'}
@@ -7389,6 +7397,11 @@ snapshots:
       - supports-color
       - yauzl
 
+  '@welldone-software/why-did-you-render@10.0.1(react@19.3.1)':
+    dependencies:
+      lodash: 4.18.1
+      react: 19.3.1
+
   '@zip.js/zip.js@2.24.0': {}
 
   abort-controller@3.0.0:
diff --git a/scripts/react/README.md b/scripts/react/README.md
index 10d4ff11e..fe07fcc62 100644
--- a/scripts/react/README.md
+++ b/scripts/react/README.md
@@ -6,6 +6,13 @@ copies of the latest 1,000 standard Profiler callback records; `.clear()` drops
 them. Records contain timing and commit metadata, never business props. Normal
 development and production builds do not load the collector.
 
+`pnpm dev:wdyr` instead initializes why-did-you-render before loading the app
+and uses its development JSX runtime. It reports avoidable renders for
+`ProxyItem`, `ProxyItemMini` and `ProxyTunCard` in the console. The modes are
+mutually exclusive; `CVR_REACT_DIAGNOSTICS` accepts only `profiler` or `wdyr` on
+the development server. Each mode uses its own Vite cache. Production builds
+ignore this variable and include neither diagnostic entry nor runtime.
+
 Install the browser explicitly with `pnpm exec playwright install chromium`.
 Then run `pnpm react:ab --base <ref> --head <ref>`. Both Git trees run against
 one installed dependency set and the same fixed DNS, delay-hook and proxy-tab
diff --git a/scripts/react/vite.mts b/scripts/react/vite.mts
index 753a7f716..4a5989866 100644
--- a/scripts/react/vite.mts
+++ b/scripts/react/vite.mts
@@ -10,10 +10,39 @@ export function reactDiagnostics(mode: string | undefined): Plugin[] {
       enforce: 'pre',
       apply: 'serve',
       config() {
-        if (mode !== 'profiler')
+        if (mode !== 'profiler' && mode !== 'wdyr')
           throw new Error(`Unknown CVR_REACT_DIAGNOSTICS mode: ${mode}`)
+        return {
+          cacheDir: path.resolve('node_modules/.vite', mode),
+          ...(mode === 'wdyr'
+            ? {
+                oxc: {
+                  jsx: {
+                    importSource: '@welldone-software/why-did-you-render',
+                  },
+                },
+                optimizeDeps: {
+                  include: [
+                    '@welldone-software/why-did-you-render',
+                    '@welldone-software/why-did-you-render/jsx-dev-runtime',
+                  ],
+                },
+              }
+            : {}),
+        }
+      },
+      transformIndexHtml(html) {
+        if (mode !== 'wdyr') return html
+        const entry = 'src="./main.tsx"'
+        if (!html.includes(entry))
+          throw new Error('WDYR entry no longer matches index.html')
+        return html.replace(
+          entry,
+          `src="/@fs/${normalizePath(path.resolve('scripts/react/wdyr.ts'))}"`,
+        )
       },
       transform(code, id) {
+        if (mode !== 'profiler') return
         if (id !== normalizePath(path.resolve('src/main.tsx'))) return
         const open = '<React.StrictMode>'
         const close = '</React.StrictMode>'
diff --git a/scripts/react/wdyr.ts b/scripts/react/wdyr.ts
new file mode 100644
index 000000000..ec8d409e9
--- /dev/null
+++ b/scripts/react/wdyr.ts
@@ -0,0 +1,10 @@
+import whyDidYouRender from '@welldone-software/why-did-you-render'
+import React from 'react'
+
+whyDidYouRender(React, {
+  include: [/^(ProxyItem|ProxyItemMini|ProxyTunCard)$/],
+  trackAllPureComponents: false,
+  trackHooks: true,
+})
+
+await import('../../src/main')
diff --git a/vite.config.mts b/vite.config.mts
index f60f5e6f0..a8a5fa3f9 100644
--- a/vite.config.mts
+++ b/vite.config.mts
@@ -9,6 +9,7 @@ import { reactDiagnostics } from './scripts/react/vite.mts'
 
 export default defineConfig({
   root: 'src',
+  cacheDir: path.resolve('node_modules/.vite/default'),
   server: { port: 3000 },
   plugins: [
     svgr(),