Capability discovery

Endpoints in Delphi are not all the same. One endpoint may be voice-only, another text-only, another a multimodal AI agent with bespoke browser-action flows. The SDK exposes a small API for querying that surface before opening a session.

getCapabilities

const capabilities = await delphi.getCapabilities(endpointId);

console.log(capabilities.interactionModes);
// → { text: true, audio_playback: true, voice_conversation: true, … }

console.log(capabilities.flows.entryPoints);
// → ['web_chat', 'web_voice', 'phone']

console.log(capabilities.runtime.migration);
// → ['text_to_voice', 'voice_to_text', 'api_to_media'] when both web entry points exist

hasCapability

Predicate form. Returns boolean.

if (!delphi.hasCapability(capabilities, 'voice_conversation')) {
  throw new Error('This endpoint does not support voice calls.');
}

assertCapability

Throws CapabilityNotSupportedError when the capability is missing.

delphi.assertCapability(capabilities, 'audio_playback');
// proceeds, or throws

assertEndpointCapability

Convenience: fetch capabilities and assert in one call.

const caps = await delphi.assertEndpointCapability(endpointId, 'audio_playback');

console.log(caps.flows.browserActions);

Session migration

capabilities.runtime.migration lists which live handoffs TelAPI supports for this endpoint:

Value	Meaning
text_to_voice	Active text session can upgrade to WebRTC voice on the same sessionId.
voice_to_text	Active voice_conversation can downgrade back to text.
api_to_media	Other API-initiated media transitions (platform-internal).

Both text_to_voice and voice_to_text appear only when the flow defines web_chat and web_voice entry points. Gate “Upgrade to voice” / “Switch to text chat” buttons on these flags — see Text chat quick start.

Browser-action discovery

capabilities.flows.browserActions enumerates the BOA flows the endpoint exposes. The fields:

Field	Meaning
id	Stable capability id, suitable for capabilityId on readAloud.
slug	URL-friendly identifier.
label	Human-readable name.
type	Capability type (e.g. read_aloud, transform_and_read, custom).
messageType	The exact browser.action.* message the server expects. Used by sendBrowserAction.
voiceInvocable	Whether the AI can trigger this BOA mid-call.

For readAloud the SDK picks the right BOA automatically; supply capabilityId or identifier only when an endpoint exposes multiple read-aloud BOAs and you need to disambiguate.

Error type

The thrown error from assertCapability / assertEndpointCapability:

import {CapabilityNotSupportedError} from '@ki-kombinat/delphi-client-js-sdk';

try {
  delphi.assertCapability(capabilities, 'voice_conversation');
} catch (err) {
  if (err instanceof CapabilityNotSupportedError) {
    console.warn(`Endpoint missing capability: ${err.capability}`);
  }
}

See Errors for the full list of typed errors the SDK exposes.

Next step

Jump into a text chat, read-aloud quick start, or a voice call.