[WEBJS] sendText returns 201 but cold outbound message later fails with ack=-1 / isSendFailure=true while physical phone succeeds

[s-alfahdawi]

Describe the bug

Outbound messages sent via POST /api/sendText are accepted by WAHA with HTTP 201, but the message later fails in WhatsApp Web history with:

• ack = -1
• ackName = ERROR
• _data.isSendFailure = true

The same recipient can receive messages successfully when the exact same WhatsApp account sends from the physical phone app.

This looks related to the existing cold-contact/LID issues, but it is not the same failure mode as GOWS 463: WEBJS accepts the message first, then WhatsApp marks it failed asynchronously.

Environment

{
"version": "2026.4.3",
"engine": "WEBJS",
"tier": "PLUS",
"platform": "linux/x64"
}

Session status is WORKING.

Related issues found before opening

• [GOWS] Error 463 on send to cold contacts — tctoken/cstoken not included in outgoing messages #1992 - GOWS cold contacts fail with 463 / missing tctoken / cstoken
• [GOWS] Error 463 on sendText — tctoken lifecycle not implemented in GOWS engine #2050 - GOWS sendText 463, physical device succeeds
• [GOWS] - sendText API returns 500 - no LID found from server #2094 - GOWS sendText 500, no LID found from server
• [WEBJS] - cannot send message #1905 - older WEBJS LID send issue

Steps to reproduce

1. Start a WAHA Plus session using WEBJS.
2. Confirm session status is WORKING.
3. Send a message to a new/cold recipient using the physical WhatsApp phone app.
4. Confirm the recipient receives that physical-phone message.
5. Call POST /api/sendText through WAHA to the same recipient using a valid @c.us chatId.
6. WAHA returns HTTP 201.
7. Read the chat history from WAHA.
8. The API-sent message is present, but has ack=-1, ackName=ERROR, and _data.isSendFailure=true.

Expected behavior

If the physical phone app can send to the recipient, WAHA WEBJS should also deliver the message or return a synchronous error explaining why it cannot.

At minimum, we need to know whether this is an expected limitation of WhatsApp Web / linked device sending to cold contacts, or a WAHA WEBJS/LID handling issue.

Actual behavior

Physical phone app message succeeds:

{
"ack": 2,
"ackName": "DEVICE",
"from": "@c.us",
"to": "@lid",
"body": "",
"isSendFailure": null
}

WAHA WEBJS API message to the same chat fails after HTTP 201:

{
"ack": -1,
"ackName": "ERROR",
"from": "@lid",
"to": "@lid",
"body": "",
"isSendFailure": true,
"error": null
}

Important observation: the physical phone message appears as sent from the phone-number identity (<phone-number>@c.us), but the WAHA API message appears as sent from a LID identity (<sender-lid>@lid). The LID-sender API messages fail.

API request

POST /api/sendText
Content-Type: application/json
X-Api-Key:

{
"session": "default",
"chatId": "@c.us",
"text": "Test message"
}

Response:

HTTP/1.1 201 Created

The response includes a message id, but the later chat history shows the message failed with ack=-1.

Additional context

We previously tried GOWS for the same production use case. GOWS failed differently for cold/new contacts with server-side errors around LID / cold-contact reachout behavior. WEBJS improved the synchronous API response, but the actual delivery still fails asynchronously.

Questions:

1. Is this a known WEBJS limitation with cold outbound messages and LID sender identity?
2. Is there a way to force WEBJS/WAHA to send from the phone-number identity instead of the LID identity?
3. Is there a recommended engine/build/configuration for reliable outbound messages to new recipients?
4. Are there additional logs or debug flags we should capture for ack=-1 / _data.isSendFailure=true cases?

I can provide full unredacted message IDs and JIDs privately if needed, but I redacted them here because this is a public issue.