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Commerce & payments

Selling inside a chat thread: catalogues and product data that have to stay true, payment requests, and the guards that decide when software is allowed to ask somebody for money.

Covered here: Razorpay payment link WhatsApp · self-deployed WhatsApp CRM · 24 hour service window · abandoned cart WhatsApp · BYO payment gateway · catalog_management scope · catalogue sync · eventual consistency · HMAC SHA256 · Hono routing collision

• 28 August 2026 · commerce

  Building a WhatsApp catalogue that tells the truth

  Meta's catalogue batch endpoint returns HTTP 200 even when every item was rejected. The script we wrote specifically to verify a token could write reported success against a catalogue that was empty and had always been empty. Eleven bugs from three weeks of building catalogue and product infrastructure, almost all of the same shape: something reporting success for work it had not done. Includes a paywall that only worked while the feature was switched off, a complete edit endpoint with no button behind 5,187 passing tests, and the two calls we got wrong ourselves.

• 7 August 2026 · engineering

  The WhatsApp business cards that started asking for money

  Two features wanted the same short URL prefix, and the newer one was mounted first. For five days, scanning any of our free digital business cards returned "This payment link is not valid." Why neither route could move (one URL is fixed inside an approved Meta template, the other is printed on paper), the three-line fallthrough that fixed it, the passing test that was quietly asserting the bug, and the telemetry blind spot that means we can never count who saw it.

• 4 August 2026 · engineering

  Five guards on automated WhatsApp payment requests

  A sequence, a rule, a completed Flow or a customer typing "how do I pay" can all produce a real payment request in the thread. Building that took a day. The rest of the work was the five things it must refuse to do: a consent check that fails closed, a duplicate-ask guard that once answered "already requested" forever about someone never asked, an oversell guard found willing to sell one ring to fifty people, a closed 24-hour window, and a ₹500 advance that used to mark a ₹2,500 order paid and shipped.

• 31 July 2026 · engineering

  WhatsApp payments with Razorpay: what the docs leave out

  Collecting payment inside a chat in India, written while shipping it. The order_details payload that passes validation, why a bare UPI VPA is rejected, the INR-only rule and how it fails silently, payment links versus subscriptions in a thread, whether your notes reach the webhook, and the signature check that rejects every real event while returning a clean boolean.

• In progress

  The half of a sale that nobody demos

  Every platform shows you the payment landing. Almost none show you the twenty minutes afterwards: who gets told, who packs it, what the buyer hears while they wait, and what happens when it ships four days later and the messaging window has closed.

• In progress

  Where the ask ends and the shop begins

  A payment request is messaging machinery. A product library is a commerce application, and the part most likely to be replaced by a real one. On finding that seam in our own code, and making it a documented extension point instead of a function that happened to sit in the middle of a file.

• In progress

  What a feature looks like when nothing consumes it

  Contact limits computed on every request and enforced nowhere. A tier ladder that is marketing copy at runtime. On the difference between building a capability and shipping one, found in our own codebase.