Aug 7 - Update new design as default

migrations/versions/phase50_default_modern_theme.py

@@ -0,0 +1,57 @@
+"""phase50 — make the modern design the default
+
+phase48 shipped the modern design as an opt-in A/B test: `users.ui_theme`
+defaulted to 'classic' and users switched themselves over. The test is settled,
+so this promotes 'modern' to the default.
+
+Two separate things have to change, and BOTH are needed:
+
+1. The column default, so NEW accounts start on modern.
+2. The existing rows. Every account created under phase48 has a literal
+   'classic' stored — not a NULL — so a default change alone would leave every
+   current user on the old design and the switch would look like it did nothing.
+
+**This overwrites a deliberate choice.** phase48 gave no way to distinguish "I
+picked classic" from "I never touched it", so anyone who actively preferred
+classic is moved too. They can switch straight back from the account menu, and
+that choice will then stick — nothing here removes the switcher.
+
+`/ui/theme-votes` reads this same column, so the A/B tally reads 100% modern
+once this runs. Capture it before deploying if the numbers still matter.
+
+To change the default WITHOUT touching saved preferences, set
+DEFAULT_UI_THEME=classic in the environment instead of running this.
+"""
+
+revision      = 'phase50_default_modern'
+down_revision = 'phase49_external_inspector'
+branch_labels = None
+depends_on    = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    # 1. New accounts start on modern.
+    op.execute(sa.text(
+        "ALTER TABLE users MODIFY COLUMN ui_theme VARCHAR(16) "
+        "NOT NULL DEFAULT 'modern'"
+    ))
+    # 2. Move everyone still on the phase48 default. Idempotent: re-running
+    #    matches nothing once every row is 'modern'.
+    op.execute(sa.text(
+        "UPDATE users SET ui_theme = 'modern' WHERE ui_theme = 'classic'"
+    ))
+
+
+def downgrade():
+    op.execute(sa.text(
+        "ALTER TABLE users MODIFY COLUMN ui_theme VARCHAR(16) "
+        "NOT NULL DEFAULT 'classic'"
+    ))
+    # Individual pre-upgrade choices were not recorded, so this returns
+    # EVERYONE to classic rather than restoring who had what.
+    op.execute(sa.text(
+        "UPDATE users SET ui_theme = 'classic' WHERE ui_theme = 'modern'"
+    ))