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Handle common app zoom shortcuts #768

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Handle common app zoom shortcuts #768

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72 changes: 72 additions & 0 deletions apps/web/src/main.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -10,11 +10,83 @@ import { isElectron } from "./env";
import { getRouter } from "./router";
import { APP_DISPLAY_NAME } from "./branding";

const APP_ZOOM_STORAGE_KEY = "t3code:app-zoom";
const APP_ZOOM_INSTALL_FLAG = "__t3codeAppZoomInstalled";
const DEFAULT_ZOOM_LEVEL = 1;
const MIN_ZOOM_LEVEL = 0.7;
const MAX_ZOOM_LEVEL = 1.8;
const ZOOM_STEP = 0.1;

const roundZoomLevel = (value: number) => Math.round(value * 10) / 10;

const clampZoomLevel = (value: number) =>
roundZoomLevel(Math.min(MAX_ZOOM_LEVEL, Math.max(MIN_ZOOM_LEVEL, value)));

const readStoredZoomLevel = () => {
const storedValue = window.localStorage.getItem(APP_ZOOM_STORAGE_KEY);
const parsedValue = Number.parseFloat(storedValue ?? "");

if (!Number.isFinite(parsedValue)) {
return DEFAULT_ZOOM_LEVEL;
}

return clampZoomLevel(parsedValue);
};
Comment on lines +25 to +34
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@macroscopeapp macroscopeapp bot Mar 10, 2026

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🟡 Medium src/main.tsx:25

readStoredZoomLevel directly accesses window.localStorage.getItem() without exception handling. When the user has disabled cookies or the page runs in a strict iframe sandbox, this throws a SecurityError that propagates uncaught to the top level, halting main.tsx before ReactDOM.createRoot and leaving users with a blank white screen. Consider wrapping the localStorage access in a try-catch that returns DEFAULT_ZOOM_LEVEL on any exception.

+const readStoredZoomLevel = () => {
+  try {
+    const storedValue = window.localStorage.getItem(APP_ZOOM_STORAGE_KEY);
+    const parsedValue = Number.parseFloat(storedValue ?? "");
+
+    if (!Number.isFinite(parsedValue)) {
+      return DEFAULT_ZOOM_LEVEL;
+    }
+
+    return clampZoomLevel(parsedValue);
+  } catch {
+    return DEFAULT_ZOOM_LEVEL;
+  }
+};
🚀 Reply "fix it for me" or copy this AI Prompt for your agent: 
In file apps/web/src/main.tsx around lines 25-34:

`readStoredZoomLevel` directly accesses `window.localStorage.getItem()` without exception handling. When the user has disabled cookies or the page runs in a strict iframe sandbox, this throws a `SecurityError` that propagates uncaught to the top level, halting `main.tsx` before `ReactDOM.createRoot` and leaving users with a blank white screen. Consider wrapping the `localStorage` access in a try-catch that returns `DEFAULT_ZOOM_LEVEL` on any exception.

Evidence trail:
apps/web/src/main.tsx lines 25-33: `readStoredZoomLevel` function with direct `window.localStorage.getItem()` call and no try-catch. Line 59: `applyZoomLevel(readStoredZoomLevel())` inside `installAppZoomControls`. Lines 87-90: `installAppZoomControls()` called at line 88, `ReactDOM.createRoot()` at line 90. The exception path is: localStorage.getItem (line 26) → readStoredZoomLevel → installAppZoomControls (line 88) → uncaught → script halts before line 90.


const applyZoomLevel = (value: number) => {
const normalizedValue = clampZoomLevel(value);
document.documentElement.style.zoom = String(normalizedValue);
window.localStorage.setItem(APP_ZOOM_STORAGE_KEY, String(normalizedValue));
};

const shouldHandleZoomShortcut = (event: KeyboardEvent) => {
const isModPressed = event.ctrlKey || event.metaKey;

if (!isModPressed || event.altKey) {
return false;
}

return ["+", "=", "-", "_", "0", "NumpadAdd", "NumpadSubtract", "Numpad0"].includes(event.key);
};

const installAppZoomControls = () => {
if ((window as Window & { [APP_ZOOM_INSTALL_FLAG]?: boolean })[APP_ZOOM_INSTALL_FLAG]) {
return;
}

(window as Window & { [APP_ZOOM_INSTALL_FLAG]?: boolean })[APP_ZOOM_INSTALL_FLAG] = true;

applyZoomLevel(readStoredZoomLevel());

window.addEventListener("keydown", (event) => {
if (!shouldHandleZoomShortcut(event)) {
return;
}

event.preventDefault();

const currentZoomLevel = readStoredZoomLevel();

if (event.key === "0" || event.key === "Numpad0") {
applyZoomLevel(DEFAULT_ZOOM_LEVEL);
return;
}

if (event.key === "+" || event.key === "=" || event.key === "NumpadAdd") {
applyZoomLevel(currentZoomLevel + ZOOM_STEP);
return;
}

applyZoomLevel(currentZoomLevel - ZOOM_STEP);
});
};

const history = isElectron ? createHashHistory() : createBrowserHistory();

const router = getRouter(history);

document.title = APP_DISPLAY_NAME;
installAppZoomControls();

ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
<React.StrictMode>
Expand Down