VAPI•7mo ago

serverMessages WebSDK

The new SDK has a bug:

    /**
     * These are the messages that will be sent to your Client SDKs. Default is conversation-update,function-call,hang,model-output,speech-update,status-update,transfer-update,transcript,tool-calls,user-interrupted,voice-input,workflow.node.started. You can check the shape of the messages in ClientMessage schema.
     * @example ["conversation-update","function-call","hang","model-output","speech-update","status-update","transfer-update","transcript","tool-calls","user-interrupted","voice-input","workflow.node.started"]
     */
    clientMessages?: 'conversation-update' | 'function-call' | 'function-call-result' | 'hang' | 'language-changed' | 'metadata' | 'model-output' | 'speech-update' | 'status-update' | 'transcript' | 'tool-calls' | 'tool-calls-result' | 'tool.completed' | 'transfer-update' | 'user-interrupted' | 'voice-input' | 'workflow.node.started';
    /**
     * These are the messages that will be sent to your Server URL. Default is conversation-update,end-of-call-report,function-call,hang,speech-update,status-update,tool-calls,transfer-destination-request,user-interrupted. You can check the shape of the messages in ServerMessage schema.
     * @example ["conversation-update","end-of-call-report","function-call","hang","speech-update","status-update","tool-calls","transfer-destination-request","user-interrupted"]
     */
    serverMessages?: 'conversation-update' | 'end-of-call-report' | 'function-call' | 'hang' | 'language-changed' | 'language-change-detected' | 'model-output' | 'phone-call-control' | 'speech-update' | 'status-update' | 'transcript' | "transcript[transcriptType='final']" | 'tool-calls' | 'transfer-destination-request' | 'transfer-update' | 'user-interrupted' | 'voice-input';

    /**
     * These are the messages that will be sent to your Client SDKs. Default is conversation-update,function-call,hang,model-output,speech-update,status-update,transfer-update,transcript,tool-calls,user-interrupted,voice-input,workflow.node.started. You can check the shape of the messages in ClientMessage schema.
     * @example ["conversation-update","function-call","hang","model-output","speech-update","status-update","transfer-update","transcript","tool-calls","user-interrupted","voice-input","workflow.node.started"]
     */
    clientMessages?: 'conversation-update' | 'function-call' | 'function-call-result' | 'hang' | 'language-changed' | 'metadata' | 'model-output' | 'speech-update' | 'status-update' | 'transcript' | 'tool-calls' | 'tool-calls-result' | 'tool.completed' | 'transfer-update' | 'user-interrupted' | 'voice-input' | 'workflow.node.started';
    /**
     * These are the messages that will be sent to your Server URL. Default is conversation-update,end-of-call-report,function-call,hang,speech-update,status-update,tool-calls,transfer-destination-request,user-interrupted. You can check the shape of the messages in ServerMessage schema.
     * @example ["conversation-update","end-of-call-report","function-call","hang","speech-update","status-update","tool-calls","transfer-destination-request","user-interrupted"]
     */
    serverMessages?: 'conversation-update' | 'end-of-call-report' | 'function-call' | 'hang' | 'language-changed' | 'language-change-detected' | 'model-output' | 'phone-call-control' | 'speech-update' | 'status-update' | 'transcript' | "transcript[transcriptType='final']" | 'tool-calls' | 'transfer-destination-request' | 'transfer-update' | 'user-interrupted' | 'voice-input';

    /**
     * These are the messages that will be sent to your Client SDKs. Default is conversation-update,function-call,hang,model-output,speech-update,status-update,transfer-update,transcript,tool-calls,user-interrupted,voice-input,workflow.node.started. You can check the shape of the messages in ClientMessage schema.
     * @example ["conversation-update","function-call","hang","model-output","speech-update","status-update","transfer-update","transcript","tool-calls","user-interrupted","voice-input","workflow.node.started"]
     */
    clientMessages?: 'conversation-update' | 'function-call' | 'function-call-result' | 'hang' | 'language-changed' | 'metadata' | 'model-output' | 'speech-update' | 'status-update' | 'transcript' | 'tool-calls' | 'tool-calls-result' | 'tool.completed' | 'transfer-update' | 'user-interrupted' | 'voice-input' | 'workflow.node.started';
    /**
     * These are the messages that will be sent to your Server URL. Default is conversation-update,end-of-call-report,function-call,hang,speech-update,status-update,tool-calls,transfer-destination-request,user-interrupted. You can check the shape of the messages in ServerMessage schema.
     * @example ["conversation-update","end-of-call-report","function-call","hang","speech-update","status-update","tool-calls","transfer-destination-request","user-interrupted"]
     */
    serverMessages?: 'conversation-update' | 'end-of-call-report' | 'function-call' | 'hang' | 'language-changed' | 'language-change-detected' | 'model-output' | 'phone-call-control' | 'speech-update' | 'status-update' | 'transcript' | "transcript[transcriptType='final']" | 'tool-calls' | 'transfer-destination-request' | 'transfer-update' | 'user-interrupted' | 'voice-input';

    /**
     * These are the messages that will be sent to your Client SDKs. Default is conversation-update,function-call,hang,model-output,speech-update,status-update,transfer-update,transcript,tool-calls,user-interrupted,voice-input,workflow.node.started. You can check the shape of the messages in ClientMessage schema.
     * @example ["conversation-update","function-call","hang","model-output","speech-update","status-update","transfer-update","transcript","tool-calls","user-interrupted","voice-input","workflow.node.started"]
     */
    clientMessages?: 'conversation-update' | 'function-call' | 'function-call-result' | 'hang' | 'language-changed' | 'metadata' | 'model-output' | 'speech-update' | 'status-update' | 'transcript' | 'tool-calls' | 'tool-calls-result' | 'tool.completed' | 'transfer-update' | 'user-interrupted' | 'voice-input' | 'workflow.node.started';
    /**
     * These are the messages that will be sent to your Server URL. Default is conversation-update,end-of-call-report,function-call,hang,speech-update,status-update,tool-calls,transfer-destination-request,user-interrupted. You can check the shape of the messages in ServerMessage schema.
     * @example ["conversation-update","end-of-call-report","function-call","hang","speech-update","status-update","tool-calls","transfer-destination-request","user-interrupted"]
     */
    serverMessages?: 'conversation-update' | 'end-of-call-report' | 'function-call' | 'hang' | 'language-changed' | 'language-change-detected' | 'model-output' | 'phone-call-control' | 'speech-update' | 'status-update' | 'transcript' | "transcript[transcriptType='final']" | 'tool-calls' | 'transfer-destination-request' | 'transfer-update' | 'user-interrupted' | 'voice-input';

You can see that the example state you can pass an array, however the type is only a OR configuration.

Vapi Support BotAPP•5/28/25, 1:40 AM

You're correct—this is a type definition bug.
According to the Vapi documentation, both clientMessagesclientMessages and

serverMessages

serverMessages

should accept an array of message types, not just a single value. The SDK's type should look like:

clientMessages?: (
  | 'conversation-update'
  | 'function-call'
  // ...other types
)[];

clientMessages?: (
  | 'conversation-update'
  | 'function-call'
  // ...other types
)[];

Action: Report this to the SDK maintainers or patch your local types to accept arrays as shown above.
See Vapi docs for reference

Sources:

⤵️ Mention @Vapi Support Bot for follow-ups 🐥

sour-pinkOP•5/28/25, 1:40 AM

And if you use the type from the SDK, that's the error:

Vapi Support BotAPP•5/28/25, 1:42 AM

To resolve the 400 error, update your local type definitions so that
serverMessages
serverMessages
and clientMessagesclientMessages accept arrays of unique message types, as required by the Vapi API:

serverMessages?: (
  | 'conversation-update'
  | 'end-of-call-report'
  | 'function-call'
  // ...other types
)[];

serverMessages?: (
  | 'conversation-update'
  | 'end-of-call-report'
  | 'function-call'
  // ...other types
)[];

Patch your SDK types as above, and ensure you only pass arrays with unique values.
See Vapi docs for reference

Sources:

Vapi Support BotAPP•5/28/25, 1:42 AM

To resolve the error, update your SDK types so that clientMessagesclientMessages and
serverMessages
serverMessages
are arrays of unique message types, not single values. For example:

clientMessages?: (
  | 'conversation-update'
  | 'function-call'
  // ...other types
)[];
serverMessages?: (
  | 'conversation-update'
  | 'end-of-call-report'
  // ...other types
)[];

clientMessages?: (
  | 'conversation-update'
  | 'function-call'
  // ...other types
)[];
serverMessages?: (
  | 'conversation-update'
  | 'end-of-call-report'
  // ...other types
)[];

Patch your local SDK types or report this to the maintainers to ensure compliance with the Vapi API requirements.
See Vapi API Reference for details

Sources:

KyleAPP•5/28/25, 11:21 PM

Hey @Alberto, thanks for reporting it let me work on it.

sour-pinkOP•5/29/25, 6:22 AM

Thanks mat!

sour-pinkOP•5/29/25, 6:27 AM

// @ts-expect-error Vapi's official documentation examples show arrays are valid for clientMessages, but the SDK's TypeScript type is currently a single string union.
clientMessages: [ "transcript",
"hang",
"function-call",
"speech-update",
"metadata",
"conversation-update" ],
// @ts-expect-error Vapi's official documentation examples show arrays are valid for serverMessages, but the SDK's TypeScript type is currently a single string union.
serverMessages: [ "end-of-call-report" ],

FYI: this is the workaround if anyone else is experiencing the same

serverMessages WebSDK

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