feat(i18n): default to browser language

docs/i18n.md

@@ -4,8 +4,9 @@
 
 Register is localized with [Lingui v5](https://lingui.dev). Supported locales: **English (en),
 Spanish (es), Korean (ko), Simplified Chinese (zh)**, plus a dev-only **pseudo** locale for
-finding unwrapped strings. English is the default; an explicit choice is persisted to
-`localStorage['register.locale']`.
+finding unwrapped strings. The first visit uses the first supported locale from the browser's language
+preferences, falling back to English. An explicit choice is persisted to
+`localStorage['register.locale']` and takes precedence on later visits.
 
 ## The one rule: reactive vs non-reactive
 
@@ -135,7 +136,7 @@ still in plain English is unwrapped. It's the primary tool for catching missed s
 
 ```js
 // in the browser console, then reload
-localStorage.setItem('register.locale', 'pseudo')
+localStorage.setItem('register.locale', JSON.stringify('pseudo'))
 ```
 
 Pseudo is only selectable in dev (`import.meta.env.DEV`); in production the value is validated

docs/wiki/log.md

@@ -1,6 +1,6 @@
 ---
 title: Log
-updated: 2026-08-08
+updated: 2026-08-19
 type: log
 ---
 
@@ -129,3 +129,7 @@ Play-by-play lives in git (PRs #1053/#1054/#1055/#1063, SDK PR #27). Durable out
 ## 2026-08-08
 
 - DTF Settings confirmation was globally gated by deploy-time schema validity, so unchanged on-chain values with display-rounding drift blocked unrelated governance changes even though those values were omitted from proposal calldata. The gate now scopes errors to changed settings while preserving no-change and changed-invalid guards; the E2E regression models an unchanged invalid distribution plus a valid mandate update.
+
+## 2026-08-19
+
+- Locale initialization now uses the first supported browser preference for visitors without a saved choice; a persisted explicit choice still wins. A clean Lingui extraction confirmed 2,543 active messages with zero missing Spanish, Korean, or Chinese translations and removed obsolete catalog entries. Live browser verification covered Spanish auto-selection plus a Korean selection surviving reload.

docs/wiki/progress.md

@@ -1,6 +1,6 @@
 ---
 title: Progress
-updated: 2026-08-10
+updated: 2026-08-19
 type: ledger
 ---
 
@@ -10,6 +10,7 @@ Stage ledger. One row per stage; keep entries short. Verifier = exact fresh comm
 
 | Stage | Status | Verifier | Review | Next |
 |---|---|---|---|---|
+| Browser locale default and translation audit | human-review-required (base a6f20e340) | RED: browser es→expected es, got en; Traditional Chinese cases initially mapped to zh · GREEN i18n 15/15 · lint · typecheck · unit 895/895 · build:no-seo · live browser: es-ES→Español, persisted ko survives reload · catalogs es/ko/zh 2543, 0 missing | independent review found Traditional→Simplified matching risks (including Hant+region); both fixed with negative and positive BCP-47 coverage; shared locale provider/persistence default requires Engineer review | PR review/merge only after Engineer review; wiki-lint blocked by pre-existing stale design-system page |
 | Preserve Index DTF section in cmd-k navigation | human-review-required (base ebcd6febe) | RED: proposal/rebalance both landed overview; GREEN 2/2 · gate typecheck/lint/880 unit · live Ctrl+K proposal→governance + rebalance→auctions | independent Intent + Engineering Risk PASS, no findings; shared route-selection behavior requires Engineer review | merge only after Engineer review; wiki-lint blocked by pre-existing stale design-system page |
 | vote modal: address-length title overflowed the dialog | done (base 6854a370b) | lint · typecheck · test:run · e2e helper units · smoke 58 · new `vote-modal-long-title` spec desktop+mobile green · RED-verified (reverted the index-dtf modal fix → checkbox right edge 943 vs dialog 849.9) | product/correctness: self — copy + layout only, no tx path touched | — |
 | Fix DTF settings confirm button | human-review-required (base 6854a370b) | RED: rounded seeded distribution blocked mandate confirm; GREEN: unit 878 incl. mapper 27/27 · focused E2E 5/5 · typecheck · lint | Dark HOLD on untested mapping → 27 exhaustive mapper tests → Dark PASS; Light PASS; CodeRabbit 2 Minor → resolved (test IDs + editable confirmed state) | PR #1084 open; Engineer review required before merge; wiki-lint blocked by pre-existing stale design-system page |

src/i18n.tsx

@@ -13,6 +13,37 @@ export type SupportedLocale = 'en' | 'es' | 'ko' | 'zh' | 'pseudo'
 
 export const DEFAULT_LOCALE: SupportedLocale = 'en'
 
+const BROWSER_LOCALES: SupportedLocale[] = ['en', 'es', 'ko']
+
+export function getBrowserLocale(): SupportedLocale {
+  if (typeof navigator === 'undefined') return DEFAULT_LOCALE
+
+  const languages = navigator.languages.length ? navigator.languages : [navigator.language]
+
+  for (const language of languages) {
+    const subtags = language.toLowerCase().split('-')
+    const locale = subtags[0] as SupportedLocale
+
+    if (locale === 'zh') {
+      if (subtags.includes('hant')) continue
+
+      if (
+        subtags.length === 1 ||
+        subtags.includes('hans') ||
+        subtags.includes('cn') ||
+        subtags.includes('sg')
+      ) {
+        return 'zh'
+      }
+      continue
+    }
+
+    if (BROWSER_LOCALES.includes(locale)) return locale
+  }
+
+  return DEFAULT_LOCALE
+}
+
 // 'pseudo' is a dev-only debugging locale that mangles every wrapped string,
 // making unwrapped (untranslated) text visually obvious.
 export const SUPPORTED_LOCALES: SupportedLocale[] = import.meta.env.DEV
@@ -48,7 +79,7 @@ export async function dynamicActivate(locale: SupportedLocale) {
 
 const storedLocaleAtom = atomWithStorage<SupportedLocale>(
   'register.locale',
-  DEFAULT_LOCALE,
+  getBrowserLocale(),
   undefined,
   { getOnInit: true }
 )