i want to override stt node in my agent. I want to process the transcript before sending it forward. How do i do it

Thanks for reaching out, Kushagra. I'm an AI assistant and I'm here to help. Give me a moment while I research this topic.

i implemented something similar and i got "no activity context found, the agent is not running" error

Sorry you hit that error — let's get it fixed. That message means the agent isn't in a running session when your

stt_node

is being used. To help diagnose, please share: • When exactly the error appears (startup, first transcript, after a while). • A short snippet showing how you create/start the AgentSession and where

stt_node

is invoked. • Any relevant log lines around the error (startup and shutdown lines). • Whether you're calling

await session.start()

and not using the STT node before that completes. Quick checklist to try now: • Ensure you call and await

session.start()

(or equivalent) before audio is sent or

stt_node

runs. • Don’t invoke agent methods after

session.close()

or outside the session lifecycle. • If you call

Agent.default.stt_node(...)

, call it from inside the running session context (not from module import time). Send the code snippet for session setup + your

stt_node

override and I’ll point out the exact spot to fix. Sources: Pipeline nodes and hooks | LiveKit Documentation | Build a multilingual voice agent that automatically switches languages | Li... | Build a multilingual voice agent that automatically switches languages | Li... | Agent session | LiveKit Documentation | https://docs.livekit.io/agents/logic/sessions.md|, with interactive elements

events = Agent.default.stt_node(self, audio, model_settings) try: agent_name = self.class.name async for event in events: ... yield event except: ...

Thanks — that snippet helps. The error means

stt_node

is running outside an active AgentSession. I need two small things to pinpoint the bug: 1. The code where you create/start the session (how you call

session.start()

/

AgentSession(...)

) — a short snippet is fine. 2. Where/when audio is being fed into the agent (are you sending audio before

await session.start()

completes?). Quick checks you can try now: • Make sure you call and await

session.start()

(or the equivalent start API) before any audio is sent or before

stt_node

is entered. • Ensure you are not calling

Agent.default.stt_node(...)

at import time or outside the agent instance’s running lifecycle. • Wrap your iteration in try/finally and avoid swallowing exceptions — log the exception to see if it’s raised before or after

events

iteration starts. If you paste the session-start snippet and where you attach/send audio, I’ll point out the exact fix. , with interactive elements

this error arises after agent transfer

Thanks — that helps. Since the error happens after an agent transfer, it likely means your

stt_node

is being invoked while the original session is closed or before the new session is fully running. Please share two small code snippets so I can pinpoint the fix: • The agent-transfer code plus how you create/start the new

AgentSession

(the call that does

session.start()

or equivalent). • Where you attach/send audio after the transfer (how/when audio frames are passed into the agent). Meanwhile try these checks: • Ensure you do not iterate

Agent.default.stt_node(...)

from the old session after transfer — only call it inside the new agent’s running session. • Await the new session’s

start()

before sending audio or entering

stt_node

. • After transfer, ensure any references to the old session/agent are cleared so no background task tries to use them. • Add logging around transfer: log session IDs, lifecycle state (starting, running, closed), and the exact time you call

Agent.default.stt_node(...)

. • In your

stt_node

override, wrap the call and iteration with try/finally and log exceptions with stack traces so we can see whether the failure happens immediately or after some events. Paste the two snippets and a few transfer-related logs and I’ll point out the exact change to fix this. , with interactive elements

for alt in event.alternatives:
                alt.text = alt.text.replace("😊", "").strip()  # example preprocessing
            if event.type == stt.SpeechEventType.FINAL_TRANSCRIPT:
                transcript = event.alternatives[0].text.lower()
                if "urgent" in transcript:
                    await self.session.say("I detected an urgent request.")

what is the difference between looping over event.alternatives and event.alternatives[0]

Good question — both are valid but serve different purposes. • Looping

for alt in event.alternatives:

processes every transcription hypothesis (all alternatives). Use this when you want to clean/normalize every candidate, compare confidences, or choose a non-top alternative later. • Using

event.alternatives[0]

accesses the top (highest-confidence) hypothesis only. Use this when you just need the best guess (common for keyword checks or sending a single transcript to an LLM). In short: loop to handle every candidate; index

[0]

when you only need the primary transcription. Sources: Pipeline nodes and hooks | LiveKit Documentation | An open source stack for real-time multimodal AI | LiveKit, with interactive elements