feat: add UPI Intent payment instrument and credential schemas

[paraskathuria-dev]

Summary

Introduces the upi_intent payment instrument and credential types, formalizing UPI Intent deep link payments in UCP. UPI (Unified Payments Interface) is India's real-time payment rail processing 14+ billion monthly transactions. This contribution enables businesses to offer UPI Intent payments within UCP's existing escalation mechanism.

What's Added

• source/schemas/shopping/types/upi_intent_instrument.json — A new instrument type where type: "upi_intent" signals to the platform that payment will be completed via an NPCI-compliant deep link. Extends payment_instrument.json via allOf. Includes optional display_name and display_logo for platform UI. No app constraints are supported — per NPCI mandate, the device OS presents the UPI app chooser and platforms must not filter or target specific apps.

• source/schemas/shopping/types/upi_intent_credential.json — A transaction-specific credential returned by the business inside a requires_escalation response. Contains the NPCI-compliant intent_uri (validated via pattern), transaction_reference (maps to NPCI tr, max 35 chars), optional qr_code_data (base64 PNG/SVG for desktop fallback), qr_code_string, and expires_at (ISO 8601 expiry). Extends payment_credential.json via allOf.

• docs/specification/examples/upi-intent-payment-handler.md — Full handler spec for com.razorpay.upi_intent demonstrating the pattern end-to-end: business prerequisites, handler config, instrument advertising, Complete Checkout → escalation flow, Razorpay Orders API integration, NPCI intent URI construction with RFC 3986 encoding rules, platform decision matrix (Android native / mobile web / iOS / desktop), HMAC-SHA256 webhook signature verification, polling protocol, and security considerations.

• mkdocs.yml — Navigation and llmstxt entries under Payment Handler Examples.

Why This Is Needed

UPI Intent differs fundamentally from UCP's card-centric credential exchange model:

• No card networks — payment flows directly between bank accounts via NPCI infrastructure
• No stored credentials — each transaction uses a one-time intent URI; no tokenization required
• Device-native app selection — the OS presents the UPI app chooser (GPay, PhonePe, Paytm, BHIM, and 200+ bank apps); platforms must not control app choice per NPCI mandate
• QR code fallback — for desktop/web contexts where upi:// cannot be launched

Businesses have been implementing this ad-hoc with no standardized escalation signal. This contribution formalizes the pattern using the existing requires_escalation mechanism — no new platform behavior is required.

Design Decisions

Schema extension pattern: Both new schemas extend the base types via allOf, consistent with card_payment_instrument.json and token_credential.json. The base schemas (payment_instrument.json, payment_credential.json) are intentionally left unchanged — they use additionalProperties: true to preserve UCP's open/extensible architecture.

No app constraints: Unlike card_payment_instrument.json which supports brand constraints, upi_intent_instrument.json intentionally omits constraints. The NPCI mandate requires all platforms to use implicit/generic intent calls; explicit app targeting violates compliance requirements.

Credential carries the intent URI: The instrument is intentionally minimal (just the type discriminator + display metadata). The transaction-specific intent_uri is generated server-side by the business/PSP and returned in the credential inside the requires_escalation response — consistent with how hosted checkout providers work.

Type discriminator: type: const: "upi_intent" follows the same discriminator pattern used by card_payment_instrument (type: const: "card").

Validation Checklist

• Schemas validate as valid JSON (JSON.parse clean)
• Both schemas conform to JSON Schema draft 2020-12
• allOf references resolve correctly against base schemas
• type discriminator uses const for unambiguous resolution
• Field names follow UCP snake_case convention
• intent_uri pattern validates NPCI-compliant upi://pay?...pa= format
• transaction_reference pattern enforces NPCI max 35 alphanumeric chars
• qr_code_data pattern validates base64 data URI format (PNG or SVG)
• All display URIs enforce HTTPS
• No secrets or sensitive values in any schema or doc
• Handler example follows the Payment Handler Guide structure
• mkdocs.yml navigation and llmstxt entries added

References

• NPCI UPI Linking Specification v1.7: https://www.npci.org.in/what-we-do/upi/product-overview
• Razorpay UPI docs: https://razorpay.com/docs/payments/payment-methods/upi/
• RFC 3986 URI Encoding: https://datatracker.ietf.org/doc/html/rfc3986
• UCP Escalation pattern: requires_escalation in checkout spec

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Contributed by Razorpay · Apache 2.0

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