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Build the catalog and shared cart in Vue, use Pinia for cart state, and let a trusted backend create and verify orders. Telegram’s Mini App API can connect the web app to its host and open an invoice, but neither the browser cart nor Telegram launch data should be treated as proof of a valid order or payment.
How the pieces fit together
- Vue renders the product catalog, cart, and checkout screens.
- Pinia holds cart data shared across those screens and provides actions and derived values.
- Telegram’s WebApp API connects the app to the Telegram host environment and provides an invoice-opening interface.
- Your backend validates Telegram launch data, checks current products and prices, creates the order, and records payment status.
This separation matters: cart contents and prices sent by a browser are requests, not authoritative order data. Telegram’s documentation also warns against trusting initDataUnsafe.
Set up Vue and Pinia
Install Pinia, create a Pinia instance, and register it on the Vue application before mounting. The official Pinia Getting Started guide shows this setup and explains how stores hold state and business logic that can be used outside a single component.
A cart store is a natural place for shared line items and actions such as adding a product, removing it, and changing its quantity. Use getters for display values such as item count or a provisional subtotal. Declare every state property in the store’s state function, as required by Pinia’s state guidance.
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Keep authoritative product records and prices on the backend. A subtotal calculated in the client can help the shopper review a cart, but it must not determine the amount charged.
Choose what belongs in the store
Cart contents need to persist as the user moves between catalog, cart, and checkout components, so shared Pinia state is appropriate. A detail used by just one component—such as whether its menu is open—can remain local to that component. This keeps global state focused on data that genuinely crosses screen boundaries.
If the app uses server-side rendering, avoid a mutable store singleton at module scope that could be shared across requests. Vue’s state management guide explains the cross-request state-sharing risk and recommends Pinia for new applications that need a store.
Connect the app to Telegram
Telegram’s Mini Apps documentation describes loading telegram-web-app.js and accessing the host API through window.Telegram.WebApp. Initialize the integration defensively: the same app may be opened in a regular browser preview, where Telegram’s host object may not exist. Keep browser-preview behavior useful rather than assuming every visit comes from Telegram.
Make the interface fit the host
- Use Telegram’s live theme parameters rather than hard-coding a light or dark palette.
- Respond to viewport changes and account for safe-area insets so important controls are not obscured by host interface elements.
- Design for a mobile-first, responsive layout and smooth interactions.
- Provide labels for inputs and meaningful labels or alternatives for images.
These are among the design considerations in Telegram’s Mini Apps guidance; test the app inside Telegram as well as in a normal browser.
Validate launch data on your backend
Send the raw initData string from the Mini App to your backend and validate it there according to Telegram’s documented process before relying on its identity or other fields. Apply an appropriate freshness check as part of that validation. Do not use initDataUnsafe or a user ID copied from frontend state as proof of identity.
Only after successful validation should the backend associate a request with a Telegram user. This creates a trusted session context for order processing; it does not make the browser’s product list, quantities, or price calculations trustworthy.
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- Review: Show the shopper the cart and its provisional totals.
- Submit a request: Send product identifiers and quantities along with the launch data needed for backend validation. Treat all browser-supplied values as untrusted input.
- Recheck on the server: Validate the Telegram data, reload current product records, verify availability, and calculate prices using server-side data.
- Create the order and payment flow: Create an order on the backend and obtain the applicable Telegram invoice or payment flow for it.
- Open the invoice: Use the Mini App’s invoice interface to present the payment flow.
- Reconcile the result: Record the final payment outcome and fulfillment state on the backend before displaying a confirmed order or starting fulfillment.
Telegram documents payment support through third-party providers and the Mini App openInvoice interface, including status reporting through the corresponding close event. Requirements depend on the item being sold and the chosen provider, so check Telegram’s current documentation and the provider’s terms for the specific product and operating region. The platform documentation does not establish one universal provider, fee, or availability rule.
Handle payment outcomes explicitly
Keep pending, successful, and cancelled outcomes distinct in the interface. Closing an invoice screen is not, by itself, proof that payment succeeded. Use the status provided by the documented flow, then reconcile it with the backend’s order and payment record before confirming the order or fulfilling it.
Quick Recap
Decide how to render and test the app
| Decision | Use this approach | Important check |
|---|---|---|
| Cart versus isolated UI state | Pinia for cart data shared across screens; component-local state for isolated details. | Keep global state limited to values that multiple parts of the app need. |
| Order authority | Backend-created order and verified payment state. | Never treat browser cart calculations as final prices or proof of payment. |
| Rendering mode | Client rendering or SSR according to the app’s needs. | With SSR, avoid a mutable store singleton shared between server requests. |
| Host environment | Telegram WebView integration, with a useful browser preview where practical. | Test both Telegram-hosted behavior and the absence of the Telegram host API. |
| Payment route | The Telegram invoice route and provider that fit the product and operating context. | Check current platform and provider rules; requirements vary by product and provider. |
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
