Courier Configuration: 'additionalProperties sms not allowed' Error in registration_code Template

[kvnsuryaa]

Issue Description

based of this #1570, I'm encountering an error while trying to implement SMS functionality in the registration_code template of Courier configuration. The error indicates that SMS is not an allowed property in this template.

Error Description

While implementing phone-based registration using Kratos, the system fails to process the SMS template configuration.

Request Details

Registration Flow Request

POST http://127.0.0.1:4433/self-service/registration?flow={flowId}

Request Body

{
    "method": "code",
    "traits": {
        "phone": "+62{rest_of_number}"
    }
}

HTTP Response

{
    "error": {
        "code": 500,
        "status": "Internal Server Error",
        "reason": "Expected sms template but got <nil>",
        "message": "An internal server error occurred, please contact the system administrator"
    }
}

Kratos Logs

kratos-kratos-1          | The configuration contains values or keys which are invalid:
kratos-kratos-1          | courier.templates.registration_code.valid: map[email:map[body:map[plaintext:file:///conf/courier-templates/registration_code/valid/sms.plaintext.gotmpl]] sms:map[body:map[plaintext:file:///conf/courier-templates/registration_code/valid/sms.plaintext.gotmpl]]]
kratos-kratos-1          |                                            ^-- additionalProperties "sms" not allowed

Investigation Findings

After investigating using master branch, I found in the config.schema.json that SMS method is not included in the allowed properties for the registration_code template.

Current Configuration

"registration_code": {
  "additionalProperties": false,
  "type": "object",
  "properties": {
    "valid": {
      "additionalProperties": false,
      "type": "object",
      "properties": {
        "email": {
          "$ref": "#/definitions/emailCourierTemplate"
        }
      },
      "required": ["email"]
    }
  }
},

Expected Behavior

I expected to be able to configure SMS delivery method in the registration_code template, similar to how other notification methods work like login_code.

Schema Definition Issue

The config.schema.json appears to be restrictive and doesn't include SMS as an allowed property for the registration_code template.

Questions

1. Is this a known limitation of the registration_code template?
2. Is there a workaround to implement SMS functionality with this template?
3. If SMS is not supported in this template, how do i sign up using phone number with OTP?

Environment

• Kratos Docker: latest
• Implementation: passwordless OTP Authentication with Twilio
• Attempted Method: SMS configuration

Additional Context

• I have confirmed this is a schema restriction rather than an implementation error
• The error occurs specifically when trying to add SMS configuration to the template