The admin browser holds a persistent HTTP connection to /order_stream. Flask streams today's orders as JSON every few seconds using SSE — no WebSocket, no Socket.IO. A background threading.Thread runs every 60 seconds and auto-marks delivery orders as delivered after 30 minutes in ready state, preventing orders from getting stuck.

Flask creates a Stripe PaymentIntent. Stripe.js collects card details in the browser — the card number never touches the Flask server. A unique reference UUID per order prevents duplicate charges on network retries. Stripe commission (3.6%) is calculated and tracked separately in the revenue dashboard. Admin cancellations trigger automatic stripe.Refund.create() calls.

Customers register with a Japanese phone number (formatted to E.164) and password. Flask calls the Twilio Verify API to send a 6-digit SMS OTP. After the customer confirms the code, is_phone_verified is set to True and they are logged in. Sessions are stored in PostgreSQL and last 31 days. Returning customers log in with phone + password only — no SMS needed.

Four distinct user types, each with separate login flows and route-level decorators: Customers (phone + password + Twilio OTP on first registration), Admins (email + password), Delivery boys (PIN — simplified login for delivery staff), and a Super admin (4-digit passcode giving full system control including menu management, site blocking, and user management).

Menu item images and PDF menus are stored in an AWS S3 bucket in the Tokyo region (ap-northeast-1). Uploads are handled server-side via boto3 through utils/s3_utils.py. The Super Admin can drag-and-drop reorder categories and items — position is updated via AJAX. Admins can toggle item availability between available, sold out today, and sold out.

The lunch category is hidden on weekends by default. The app queries the Nager.Date API to detect Japanese national holidays and adjusts lunch visibility accordingly. Admins can override this toggle manually. All categories, items, and add-ons are loaded in a single optimised database query using eager loading for speed.

The public contact form detects whether a message contains Japanese characters via regex. If the message is Japanese, it is sent via Zoho Mail SMTP (smtp.zoho.in). If English-only, a success response is shown but no email is sent — a deliberate spam filter to block automated English-language bots while staying functional for real Japanese customers.

1. 1Customer enters name, Japanese phone number, password
2. 2Server formats phone to E.164 (+81…), checks for duplicates
3. 3Account created; Twilio Verify API sends 6-digit SMS
4. 4Customer enters the OTP on the verify screen
5. 5Flask validates code via Twilio Checks API
6. 6Phone verified → customer logged in, redirected to menu

1. 1Customer selects delivery or pickup, time slot, payment method
2. 2For card/PayPay: Flask creates a Stripe PaymentIntent
3. 3Stripe.js handles card input in the browser — details never reach Flask
4. 4On success: browser calls /store_order_details, Flask saves order and clears cart
5. 5For cash on delivery: order saved immediately, no Stripe call
6. 6Customer redirected to payment success page

1. 1Admin opens /admin/orders; browser connects to SSE stream
2. 2New orders appear live without page refresh
3. 3Admin clicks status buttons → AJAX updates database
4. 4Status flow: pending → preparing → ready → delivered / completed / cancelled
5. 5Background thread auto-delivers after 30 min in ready state
6. 6Cancellation triggers automatic Stripe refund

1. 1Super admin logs in at /control-center with 4-digit passcode
2. 2Adds, edits, or deletes categories and menu items
3. 3Images uploaded to AWS S3 via boto3
4. 4Add-on groups (spice levels, drinks) configured per category or item
5. 5Drag-and-drop reordering updates position field via AJAX
6. 6Item availability toggled: available / sold out today / sold out