feat(desktop): default UI zoom to Appearance 90% preset

Land on the exact 90% scale so the settings control shows a selection
on fresh installs, instead of five Ctrl+- steps (~91%) between presets.

apps/desktop/e2e/fixtures.ts

@@ -121,10 +121,10 @@ export function createSandbox(prefix: string): Sandbox {
   )
 
   // Pin Chromium actual-size zoom (level 0) for the suite. Fresh installs
-  // ship DEFAULT_ZOOM_LEVEL ≈ -0.5 (~91%), but Playwright click hit-testing
-  // and the committed visual baselines were calibrated at 100%. Without this
-  // file every sandbox would inherit the product default and fail pointer
-  // interception + snapshot diffs.
+  // ship DEFAULT_ZOOM_LEVEL at the Appearance 90% preset, but Playwright
+  // click hit-testing and the committed visual baselines were calibrated at
+  // 100%. Without this file every sandbox would inherit the product default
+  // and fail pointer interception + snapshot diffs.
   fs.writeFileSync(
     path.join(userDataDir, 'zoom-state.json'),
     JSON.stringify({ zoomLevel: 0 }, null, 2),

apps/desktop/electron/zoom.test.ts

@@ -26,10 +26,10 @@ test('storage key stays stable so persisted zoom survives upgrades', () => {
   assert.equal(ZOOM_STORAGE_KEY, 'hermes:desktop:zoomLevel')
 })
 
-test('default zoom is five Ctrl/Cmd+- steps out from Chromium 0', () => {
+test('default zoom matches the Appearance 90% preset', () => {
   assert.equal(ZOOM_STEP, 0.1)
-  assert.equal(DEFAULT_ZOOM_LEVEL, -0.5)
-  assert.equal(zoomLevelToPercent(DEFAULT_ZOOM_LEVEL), 91)
+  assert.equal(zoomLevelToPercent(DEFAULT_ZOOM_LEVEL), 90)
+  assert.equal(DEFAULT_ZOOM_LEVEL, percentToZoomLevel(90))
 })
 
 test('clampZoomLevel rejects garbage and enforces bounds', () => {

apps/desktop/electron/zoom.ts

@@ -5,8 +5,8 @@
  * Chromium actual-size baseline); Chromium's internal unit is the zoom level,
  * where factor = 1.2 ^ level.
  *
- * Our shipped default is five Ctrl/Cmd+- steps out from Chromium 0 — a slightly
- * tighter UI that still lands near the 90% Appearance preset.
+ * Our shipped default is the Appearance 90% preset — tight enough to feel
+ * denser than Chromium 100%, and selected in the UI Scale control on first run.
  */
 
 export const ZOOM_STORAGE_KEY = 'hermes:desktop:zoomLevel'
@@ -18,8 +18,8 @@ const MAX_ZOOM_LEVEL = 9
 /** Half Chromium's default step; matching the shortcuts and View menu. */
 export const ZOOM_STEP = 0.1
 
-/** Five Ctrl/Cmd+- presses from Chromium 0 (~91%). Fresh installs + Actual Size. */
-export const DEFAULT_ZOOM_LEVEL = -5 * ZOOM_STEP
+/** Appearance 90% preset. Fresh installs + Actual Size / Ctrl+0. */
+export const DEFAULT_ZOOM_LEVEL = Math.log(0.9) / Math.log(ZOOM_FACTOR_BASE)
 
 export function clampZoomLevel(value) {
   if (!Number.isFinite(value)) {

apps/desktop/src/app/settings/appearance-settings.tsx

@@ -65,10 +65,10 @@ function ThemePreview({ name, mode }: { name: string; mode: 'light' | 'dark' })
 }
 
 // UI scale presets, as zoom percentages. 100 is Chromium's actual-size
-// baseline; the shipped default is five Ctrl/Cmd+- steps out (~91%). Ids
-// double as the percent values sent to the main process. A Cmd/Ctrl +/-
-// step landing between presets highlights nothing, and the row description
-// keeps showing the exact current percent.
+// baseline; the shipped default is the 90% preset. Ids double as the percent
+// values sent to the main process. A Cmd/Ctrl +/- step landing between
+// presets highlights nothing, and the row description keeps showing the
+// exact current percent.
 const UI_SCALE_PRESETS = ['90', '100', '110', '125', '150', '175'] as const
 
 type UiScalePreset = (typeof UI_SCALE_PRESETS)[number]

apps/desktop/src/store/zoom.ts

@@ -10,9 +10,9 @@
 
 import { atom } from 'nanostores'
 
-// Mirror DEFAULT_ZOOM_LEVEL (-0.5 ≈ 91%) so Appearance doesn't flash 100% before
+// Mirror DEFAULT_ZOOM_LEVEL (90%) so Appearance doesn't flash 100% before
 // the main-process zoom.get() resolves. Keep in sync with electron/zoom.ts.
-export const $zoomPercent = atom<number>(91)
+export const $zoomPercent = atom<number>(90)
 
 export function setZoomPercent(percent: number): void {
   window.hermesDesktop?.zoom?.setPercent(percent)