Aug 7 - Update: UI change - MT16

config.py

@@ -88,6 +88,19 @@ class Config:
     # a TenantSettings column only if a tenant ever has a real reason to opt out.
     PHOTO_STAMP_ENABLED = os.environ.get('PHOTO_STAMP_ENABLED', 'true').lower() == 'true'
 
+    # ── Web portal design (MT-16) ───────────────────────────────────────────
+    # Fallback design for users who have never chosen one. A stored
+    # users.ui_theme ALWAYS wins, so this only affects accounts that have not
+    # touched the switcher.
+    #
+    # Defaults to 'classic' — deliberately NOT ST's 'modern'. ST is
+    # single-tenant and could decide for its own users; MT serves tenants who
+    # never saw the A/B test, and flipping every user of every tenant to a new
+    # UI on a migration is not a change to make on their behalf. New tenants can
+    # be provisioned with DEFAULT_UI_THEME=modern, and any user can opt in from
+    # the account menu at any time.
+    DEFAULT_UI_THEME = os.environ.get('DEFAULT_UI_THEME', 'classic').strip().lower()
+
     # ── Photo retention (MT-13) ─────────────────────────────────────────────
     # Days after an issue is RESOLVED before its photo FILES are deleted by
     # POST /notifications/purge-old-photos. Unset (None) = the purge is a no-op.