[alejandro-mero]

Summary

Prevents formatBRNumber from unconditionally stripping the 9th digit on Brazilian mobile numbers when DDD >= 31.

Problem

In pkg/utils/utils.go, formatBRNumber was stripping the 9th digit for any 13-digit Brazilian mobile number where DDD >= 31 (e.g. Paraná DDD 45, Santa Catarina DDD 48, Minas Gerais DDD 31, etc.):

if firstDigitNum >= 7 && dddNum >= 31 {
    return jid[:4] + jid[5:]
}

Historically, WhatsApp mapped some older Brazilian accounts outside DDD 11–28 with 8-digit JIDs. However, all Brazilian mobile lines nationwide have had 9 digits since Anatel completed the rollout in 2016. Modern WhatsApp accounts are registered natively with the full 9 digits.

When sending a message to a modern 13-digit number (e.g., 5545920031456), formatBRNumber strips the 9, converting it to +554520031456@s.whatsapp.net. Because that 8-digit variant does not exist on WhatsApp, the server returns an HTTP 500 error:
{"error":"number +554520031456@s.whatsapp.net is not registered on WhatsApp"}.

Solution

Preserve the 13-digit number provided by the caller so whatsmeow can address the user with their legitimate JID without mutating the digits.

• Legacy numbers with 12 digits remain untouched.
• Modern numbers with 13 digits are preserved as-is.
• Unit tests in pkg/utils/utils_test.go updated and passing.

Summary by Sourcery

Preserve modern Brazilian mobile numbers without removing their 9th digit.

Bug Fixes:

• Preserve the full 13-digit format of modern Brazilian mobile numbers so WhatsApp JIDs remain valid and messages can be delivered correctly.

Tests:

• Update Brazilian number formatting and JID parsing tests to expect 13-digit mobile numbers to remain unchanged.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

The PR fixes Brazilian mobile JID generation by removing the legacy rule that stripped the 9th digit for DDDs >= 31. formatBRNumber now preserves input numbers unchanged, and related formatting, JID creation, and parsing tests verify the full modern 13-digit representation.

Flow diagram for Brazilian number preservation

flowchart TD
    A[Caller provides Brazilian number] --> B[formatBRNumber]
    B --> C[Return jid unchanged]
    C --> D[whatsmeow uses full 13-digit JID]
    D --> E[Message addresses registered WhatsApp number]

Loading

File-Level Changes

Change	Details	Files
Stop rewriting Brazilian mobile numbers and preserve the caller-provided 13-digit format.	Remove the DDD, prefix, and length-based logic that stripped the 9th digit. Return Brazilian numbers unchanged, including legacy 12-digit and modern 13-digit forms. Document that nationwide Brazilian mobile numbers now use 9 digits and that preserving them avoids invalid WhatsApp JIDs.	pkg/utils/utils.go
Update number-formatting and JID-generation expectations for preserved Brazilian mobile digits.	Change formatting tests to expect the 9th digit to remain. Update CreateJID and ParseJID expectations to use the full 13-digit Brazilian number.	pkg/utils/utils_test.go

Possibly linked issues

• #unknown: The PR directly fixes the reported behavior by preserving 13-digit Brazilian mobile numbers instead of stripping their ninth digit.

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[sourcery-ai]

Hey - I've reviewed your changes and they look great!

Sourcery assessment

Needs a human reviewer. If preserving the ninth digit is wrong for some Brazilian numbers, messages may fail to reach the intended WhatsApp account or could be routed to a different account, and any messages already sent cannot be undone by reverting. The impact is bounded to affected Brazilian recipients and is normally repairable by correcting the formatting and retrying.

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