diff --git a/docs/HANDOFF.md b/docs/HANDOFF.md
index 56b1481..3db3502 100644
--- a/docs/HANDOFF.md
+++ b/docs/HANDOFF.md
@@ -26,6 +26,7 @@ The repository now has a tested identity/authentication foundation, tenant/owner
 - Fail-closed scope checks for project, graph, simulation, report, and task IDs in path/query/body.
 - Cross-tenant regression tests for project/simulation/report/task access.
 - Frontend auth store using cookie sessions, `/login` view, protected workspace router guard, and localized Thai/English login copy.
+- Production `/login` white screen root cause fixed locally (2026-09-01): raw `@` in `auth.emailPlaceholder` was invalid vue-i18n linked-message syntax and raised compiler code 10 during render. th/en now use `name{'@'}company.com`; an all-message compiler regression passes. Frontend **11 tests** + production build pass; Chrome rendered DOM contains the login UI. Pending: fresh review, push/redeploy, then live verification.
 - Frontend report-status client corrected to POST `{ task_id, simulation_id }`.
 - Durable local memory tables and a tenant-scoped SQLAlchemy repository.
 - Durable `jobs`, idempotency records, and audit-log schema with migrations `0004_operations` through `0006_job_metadata`; `TaskManager` binds to the current app/session factory, fails closed when an app context has no factory, and has SQL-level tenant/owner filters.
diff --git a/docs/engineering-log.md b/docs/engineering-log.md
index 1fbce63..d691b97 100644
--- a/docs/engineering-log.md
+++ b/docs/engineering-log.md
@@ -5,7 +5,7 @@
 | Milestone | Status | Last verified | Evidence | Next action |
 |---|---|---|---|---|
 | Baseline architecture study | complete | 2026-08-23 | `npm run build` passed; `compileall` passed; `git diff --check` passed; source inventory completed | Review MiroFish SaaS plan and lock M0 decisions |
-| Thai/English frontend hardening | bounded active-surface gate | 2026-08-24 | Frontend contract tests **10 passed**; production build passed; active routed UI has no hardcoded CJK visible strings; legacy unused `Process.vue` (Chinese copy) retired — router uses `MainView.vue`; mobile viewport capture not yet verified | Migrate remaining legacy views and perform real 320×568 and 500×768 capture when browser permission is available |
+| Thai/English frontend hardening | production login root cause fixed; redeploy pending | 2026-09-01 | Root cause of `/login` white screen proved with a RED vue-i18n compiler test: `auth.emailPlaceholder = "name@company.com"` is invalid linked-message syntax and throws compiler code 10 (`Invalid linked format`) while LoginView renders. Escaped as `name{'@'}company.com` in th/en. Recursive compiler regression covers every translation; frontend tests **11 passed**, production build passed (`index-B4oVHpLg.js`), Chrome rendered DOM contains `login-card`, Thai heading, and rendered `name@company.com`; screenshot analysis unavailable because vision provider returned 401 | Complete fresh reviewer gate, then commit/push/redeploy and verify live `/login` |
 | Zep replacement | bounded local E2E slice | 2026-08-24 | Local graph → profile → simulation config → report tools → persisted report regression passed; default remains Zep; no full consumer cutover or semantic parity claim | Cut over remaining consumers and close semantic/E2E gaps |
 | Auth/tenant/roles | bounded foundation | 2026-08-24 | Identity/session/roles/CSRF/CORS/idempotency/resource guards covered by focused tests; durable task app-state leak fixed; task query filters now push tenant predicates into SQL | Complete broader tenant matrix, admin UI, rate limits, audit/usage policy |
 | SaaS foundation batch | in progress | 2026-08-24 | Backend full suite **193 passed** after app/factory isolation, SQLite-FK, auxiliary API auth/CSRF/idempotency, cross-route/multipart idempotency, local consumer-boundary fixes, durable product-resource schema/repository, tenant-scoped `ArtifactStore`, durable `JobQueue`+`worker.py`, versioned redacted `PlatformSettings`, durable `RateLimiter` (wired to login), durable LLM `UsageService`, durable redacted `AuditService`, and durable single-use `PasswordResetService` + endpoints (also covers invite-pending setup); schema/TaskManager regression **16 passed**; auxiliary security **8 passed**; idempotency API **5 passed**; local import-boundary regression **9 fresh-import tests**; product-resource persistence **21 tests**; artifact store **12 tests**; job queue/worker **10 tests**; settings service **4 tests**; rate limiter **6 tests**; usage service **4 tests**; audit service **3 tests**; password reset **6 tests**; frontend gates passed; bounded reviewers passed their exact slices; hardened bases ready; remaining: resource authz matrix completion, admin/bootstrap UI, and deploy topology; `ruff` unavailable; no commit/push/deploy | Complete admin UI, authz matrix, then deploy topology; do not claim full-system approval |
diff --git a/docs/engineering-log/2026-09-01-login-white-screen.md b/docs/engineering-log/2026-09-01-login-white-screen.md
new file mode 100644
index 0000000..d5c2b77
--- /dev/null
+++ b/docs/engineering-log/2026-09-01-login-white-screen.md
@@ -0,0 +1,60 @@
+# 2026-09-01 — Production Login White-Screen Root Cause
+
+## Status
+
+Root cause fixed locally; fresh review and production redeploy pending.
+
+## Incident
+
+Production redirected unauthenticated users to `/login`, then rendered a blank page. The browser console reported:
+
+```text
+SyntaxError: 10
+... nextToken -> parse
+```
+
+Earlier hypotheses around cache, gzip transport, stale assets, and minified line length were disproved: the served JavaScript asset matched the local build byte-for-byte and passed `node --check`.
+
+## Verified root cause
+
+`LoginView.vue` renders `t('auth.emailPlaceholder')`. Both `locales/th.json` and `locales/en.json` contained:
+
+```json
+"emailPlaceholder": "name@company.com"
+```
+
+vue-i18n treats `@` as linked-message syntax. Direct compiler reproduction returned:
+
+```text
+code 10: Invalid linked format
+code 14: Unexpected lexical analysis
+code 13: Unexpected empty linked key
+```
+
+A RED regression test that compiles every Thai and English message failed specifically at `th:auth.emailPlaceholder`, matching production error code 10.
+
+## Fix
+
+- Escape the literal at-sign using vue-i18n syntax: `name{'@'}company.com` in both locales.
+- Add a recursive contract test using `@intlify/message-compiler` `baseCompile` for every string in both translation dictionaries.
+
+The rendered translation remains `name@company.com`.
+
+## Verification
+
+- RED focused test: failed at `th:auth.emailPlaceholder` with code 10 before the fix.
+- Reviewer cycle 1 failed closed because the initial compiler test skipped strings nested inside locale arrays and used an internal compiler package. The test was corrected to recurse arrays, use vue-i18n's public `createI18n/global.t` API, and assert the visible placeholder value.
+- Frontend tests: **11 passed, 0 failed**.
+- Production build: **699 modules**, `index-B4oVHpLg.js`, build passed.
+- Chrome headless rendered DOM from the production build contains `login-card`, `เข้าสู่ระบบ CrowdSight`, and `name@company.com`.
+- Browser runtime log contained no `SyntaxError` or uncaught exception.
+- Screenshot file was produced at 1280×800, but image-model analysis was unavailable because the configured vision provider returned HTTP 401; this remains an explicit visual-analysis gap.
+- `git diff --check`: passed.
+- Static dangerous-pattern scan on added lines: no findings.
+
+## Remaining
+
+1. Obtain a fresh independent reviewer verdict on the current diff.
+2. Commit/push after review.
+3. Rebuild EasyPanel and verify live `/login` uses the fresh chunk and renders visibly.
+4. Mobile visual QA remains deferred as previously agreed.
diff --git a/frontend/tests/i18n-contract.test.mjs b/frontend/tests/i18n-contract.test.mjs
index d78e1d0..fe1f2c2 100644
--- a/frontend/tests/i18n-contract.test.mjs
+++ b/frontend/tests/i18n-contract.test.mjs
@@ -2,6 +2,7 @@ import assert from 'node:assert/strict'
 import fs from 'node:fs'
 import path from 'node:path'
 import test from 'node:test'
+import { createI18n } from 'vue-i18n'
 
 const repoRoot = path.resolve(import.meta.dirname, '../..')
 const read = relativePath => fs.readFileSync(path.join(repoRoot, relativePath), 'utf8')
@@ -20,6 +21,19 @@ const flattenKeys = (value, prefix = '') => {
   return keys.sort()
 }
 
+const flattenStringKeys = (value, prefix = '') => {
+  const keys = []
+  for (const [key, child] of Object.entries(value)) {
+    const fullKey = prefix ? `${prefix}.${key}` : key
+    if (child && typeof child === 'object') {
+      keys.push(...flattenStringKeys(child, fullKey))
+    } else if (typeof child === 'string') {
+      keys.push(fullKey)
+    }
+  }
+  return keys.sort()
+}
+
 test('locale registry exposes only Thai and English', () => {
   const languages = parseJson('locales/languages.json')
   assert.deepEqual(Object.keys(languages).sort(), ['en', 'th'])
@@ -34,6 +48,26 @@ test('Thai and English translation dictionaries have the same keys', () => {
   )
 })
 
+test('every translation message compiles through the vue-i18n public API', () => {
+  const messages = {
+    th: parseJson('locales/th.json'),
+    en: parseJson('locales/en.json'),
+  }
+  const i18n = createI18n({ legacy: false, locale: 'th', messages })
+
+  for (const locale of ['th', 'en']) {
+    i18n.global.locale.value = locale
+    for (const keyPath of flattenStringKeys(messages[locale])) {
+      assert.doesNotThrow(
+        () => i18n.global.t(keyPath),
+        `${locale}:${keyPath} is not valid vue-i18n syntax`,
+      )
+    }
+  }
+
+  assert.equal(i18n.global.t('auth.emailPlaceholder'), 'name@company.com')
+})
+
 test('frontend i18n uses Thai as the safe default and fallback', () => {
   const source = read('frontend/src/i18n/index.js')
   assert.match(source, /DEFAULT_LOCALE\s*=\s*['"]th['"]/)
diff --git a/locales/en.json b/locales/en.json
index b1d9633..0af132f 100644
--- a/locales/en.json
+++ b/locales/en.json
@@ -35,7 +35,7 @@
     "title": "Sign in to CrowdSight",
     "subtitle": "Use your company account to continue.",
     "email": "Email",
-    "emailPlaceholder": "name@company.com",
+    "emailPlaceholder": "name{'@'}company.com",
     "password": "Password",
     "passwordPlaceholder": "Enter your password",
     "signIn": "Sign in",
diff --git a/locales/th.json b/locales/th.json
index 210d11c..f559d82 100644
--- a/locales/th.json
+++ b/locales/th.json
@@ -35,7 +35,7 @@
     "title": "เข้าสู่ระบบ CrowdSight",
     "subtitle": "ใช้บัญชีบริษัทเพื่อดำเนินการต่อ",
     "email": "อีเมล",
-    "emailPlaceholder": "name@company.com",
+    "emailPlaceholder": "name{'@'}company.com",
     "password": "รหัสผ่าน",
     "passwordPlaceholder": "กรอกรหัสผ่าน",
     "signIn": "เข้าสู่ระบบ",