Aug 7 - Update: UI change - MT16

migrations/versions/phase52_user_ui_theme.py

@@ -0,0 +1,72 @@
+"""phase52 — per-user web portal design preference
+
+Adds to `users`:
+
+    ui_theme  VARCHAR(16) NOT NULL DEFAULT 'classic'
+
+'classic' renders the original top-navbar shell (layouts/classic.html),
+'modern' renders the sidebar shell (layouts/modern.html). Every existing
+account starts on 'classic', so the portal looks and behaves exactly as before
+until a user opts in from the account menu.
+
+MULTI-TENANT NOTE — why this differs from ST
+--------------------------------------------
+ST shipped this as phase48 (default 'classic') and then phase50, which flipped
+the column default to 'modern' AND ran
+
+    UPDATE users SET ui_theme = 'modern' WHERE ui_theme = 'classic'
+
+overwriting every saved preference. That was a defensible call for a
+single-tenant deployment deciding for its own staff after its own A/B test.
+
+It is NOT portable to MT. Here the same statement would run against EVERY
+tenant database, flipping the entire UI for tenants who never saw the test and
+never asked. So MT ships the phase48 semantics only: the column defaults to
+'classic' and there is no backfill of any kind.
+
+The default for accounts that have never chosen is config DEFAULT_UI_THEME
+(app/__init__.py::resolve_ui_theme), which reads the environment. A stored
+users.ui_theme always wins over it. To put a tenant on the modern design by
+default, set DEFAULT_UI_THEME=modern for that tenant's process — no migration,
+no overwritten preferences, and individual users can still switch either way.
+
+Uses an INFORMATION_SCHEMA existence check — safe to re-run.
+"""
+
+revision      = 'phase52_user_ui_theme'
+down_revision = 'phase51_external_inspector'
+branch_labels = None
+depends_on    = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def _column_exists(conn, table, column):
+    return conn.execute(sa.text(
+        "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS "
+        "WHERE TABLE_SCHEMA = DATABASE() "
+        "AND TABLE_NAME = :t AND COLUMN_NAME = :c"
+    ), {"t": table, "c": column}).scalar() > 0
+
+
+def upgrade():
+    bind = op.get_bind()
+    if not _column_exists(bind, 'users', 'ui_theme'):
+        op.execute(sa.text(
+            "ALTER TABLE users "
+            "ADD COLUMN ui_theme VARCHAR(16) NOT NULL DEFAULT 'classic'"
+        ))
+    # Idempotent repair for any row holding a value outside the known set (for
+    # example a partially-applied earlier run). This only ever touches NULL or
+    # invalid values — it does NOT reset a user's deliberate 'modern' choice.
+    op.execute(sa.text(
+        "UPDATE users SET ui_theme = 'classic' "
+        "WHERE ui_theme IS NULL OR ui_theme NOT IN ('classic', 'modern')"
+    ))
+
+
+def downgrade():
+    bind = op.get_bind()
+    if _column_exists(bind, 'users', 'ui_theme'):
+        op.execute(sa.text("ALTER TABLE users DROP COLUMN ui_theme"))