Thanks — you're asking how to handle the first message and use

session.say()

when using the Gemini realtime model. Here's the concise guidance and recommended options. Key facts • Gemini realtime does not support

session.say()

directly because realtime models generate audio natively and don't use the scripted TTS call. • You can still have an initial spoken reply from Gemini by using

generate_reply()

with an

instructions

prompt or by setting session-level

instructions

that instruct the model to greet the user at session start. Options • Immediate spoken first message (no

session.say()

): 1. Start the session with instructions that cause an immediate greeting:

session = AgentSession(
  llm=google.realtime.RealtimeModel(
    instructions="You are a helpful assistant. Greet the user when the session starts."
  )
)
# or
session.generate_reply(instructions="Greet the user with 'Hello, how can I help you today?'")

• Use

session.say()

behavior (text → TTS) — if you need scripted control over speech: 1. Configure Gemini in text-only mode and attach a separate TTS engine:

session = AgentSession(
  llm=google.realtime.RealtimeModel(modalities=["TEXT"]),
  tts="cartesia/sonic-3"
)
# Then:
session.say("Hello, how can I help you today?")

1. This keeps realtime understanding but uses the external TTS for deterministic/scripting needs. Which should you use? • If you want Gemini to start speaking naturally and react in realtime: use

generate_reply()

or session

instructions

. • If you need exact scripted phrases (controlled TTS output) or want to call

session.say()

programmatically: use Gemini in

TEXT

modality + external TTS. If you want, tell me which environment/language you’re using (Python, TypeScript, or other) and whether you need deterministic scripted phrases or adaptive realtime speech — I’ll provide exact code for that path. Sources: Realtime models overview | LiveKit Documentation | Agent speech and audio | LiveKit Documentation | Gemini Live API plugin | LiveKit Documentation, with interactive elements