feat: cheapest pipeline — gpt-4o-mini-transcribe + gpt-5.4-nano + TTS

Simple 3-step chat completions pipeline at ~/usr/bin/bash.019/min total.
Streams PCM16 audio from frontend, transcribes on release,
generates response via gpt-5.4-nano, speaks via OpenAI TTS.

Cost breakdown:
  gpt-4o-mini-transcribe: /usr/bin/bash.003/min
  gpt-5.4-nano:          ~/usr/bin/bash.001/min
  OpenAI TTS (nova):     /usr/bin/bash.015/min
  Total:                 ~/usr/bin/bash.019/min (~/usr/bin/bash.57/day at 30min)
This commit is contained in:
2026-06-04 13:51:35 -04:00
parent 66e799a655
commit f2a5416408
3 changed files with 167 additions and 356 deletions
+162 -120
View File
@@ -1,6 +1,7 @@
"""Kira — AI body double backend
Hybrid pipeline: gpt-realtime-whisper (streaming STT) → gpt-5.4-nano (LLM) → OpenAI TTS
Cheapest pipeline: gpt-4o-mini-transcribe STT → gpt-5.4-nano LLM → OpenAI TTS
~$0.019/min total, simple 3-step chat completions.
"""
import json
@@ -13,7 +14,6 @@ from fastapi import FastAPI, WebSocket, WebSocketDisconnect
from fastapi.middleware.cors import CORSMiddleware
from config import settings
from services.hybrid import HybridPipeline
from services.memory import kira_memory
logging.basicConfig(level=logging.INFO)
@@ -29,6 +29,25 @@ app.add_middleware(
allow_headers=["*"],
)
# System prompt
BASE_SYSTEM_PROMPT = (
"You are Kira, a warm, kind, and encouraging AI body double. "
"You speak in a friendly, girly-pop tone. You are helping someone with ADHD "
"stay focused and on task. Keep responses short, supportive, and uplifting. "
"Check in on them. Remind them to take breaks. Celebrate small wins. "
"Use occasional emoji but don't overdo it. Never be judgmental."
)
_openai = None
def get_openai():
global _openai
if _openai is None:
from openai import AsyncOpenAI
_openai = AsyncOpenAI(api_key=settings.openai_api_key)
return _openai
@app.on_event("startup")
async def startup():
@@ -44,6 +63,69 @@ async def health():
return {"status": "ok", "name": "kira", "memory": mem_status}
def build_system_prompt(user_id: str) -> str:
prompt = BASE_SYSTEM_PROMPT
if kira_memory.enabled:
try:
kira_memory.ensure_peers(user_id)
suffix = kira_memory.build_system_prompt_suffix()
if suffix:
prompt += suffix
except Exception as e:
logger.warning(f"Memory context failed: {e}")
return prompt
async def run_conversation(text: str, user_id: str) -> str:
"""STT → LLM → TTS using the cheapest models."""
system_prompt = build_system_prompt(user_id)
client = get_openai()
# LLM
resp = await client.chat.completions.create(
model="gpt-5.4-nano",
messages=[
{"role": "system", "content": system_prompt},
{"role": "user", "content": text},
],
max_tokens=300,
temperature=0.7,
)
kira_text = resp.choices[0].message.content or "Mhm, I'm here!"
return kira_text
async def transcribe_audio(audio_bytes: bytes) -> str | None:
"""Transcribe audio bytes using cheapest STT model."""
client = get_openai()
try:
transcript = await client.audio.transcriptions.create(
model="gpt-4o-mini-transcribe",
file=("audio.webm", audio_bytes, "audio/webm"),
response_format="text",
)
return transcript.strip() if transcript and transcript.strip() else None
except Exception as e:
logger.warning(f"STT error: {e}")
return None
async def synthesize_speech(text: str) -> bytes:
"""Generate TTS audio from text."""
client = get_openai()
try:
resp = await client.audio.speech.create(
model="tts-1",
voice="nova",
input=text,
response_format="opus",
)
return resp.content
except Exception as e:
logger.warning(f"TTS error: {e}")
return b""
@app.websocket("/api/ws")
async def conversation_ws(websocket: WebSocket):
await websocket.accept()
@@ -52,92 +134,8 @@ async def conversation_ws(websocket: WebSocket):
identified = False
logger.info(f"[{session_id}] WebSocket connected")
pending_transcripts: list[str] = []
pipeline: HybridPipeline | None = None
pipeline_task: asyncio.Task | None = None
pipeline_ready = asyncio.Event()
audio_queue: asyncio.Queue[bytes] = asyncio.Queue()
text_queue: asyncio.Queue[str] = asyncio.Queue()
memory_suffix = ""
async def on_ready():
pipeline_ready.set()
logger.info(f"[{session_id}] Pipeline ready")
async def on_transcript_delta(delta: str):
"""Streaming partial transcript."""
await websocket.send_json({"type": "transcript_delta", "text": delta})
async def on_transcript_done(full: str):
"""Full utterance received."""
await websocket.send_json({"type": "transcript", "role": "user", "text": full})
async def on_audio_delta(audio_bytes: bytes):
"""Forward TTS audio to client."""
try:
audio_b64 = base64.b64encode(audio_bytes).decode("utf-8")
await websocket.send_json({"type": "audio", "data": audio_b64})
except Exception:
pass
async def on_speech_start():
await websocket.send_json({"type": "speaking_start"})
async def on_speech_end():
await websocket.send_json({"type": "speaking_end"})
async def on_error(msg: str):
await websocket.send_json({"type": "error", "message": msg})
# Create pipeline
pipeline = HybridPipeline(
on_transcript_delta=on_transcript_delta,
on_transcript_done=on_transcript_done,
on_audio_delta=on_audio_delta,
on_speech_start=on_speech_start,
on_speech_end=on_speech_end,
on_ready=on_ready,
on_error=on_error,
memory_suffix=memory_suffix,
)
pipeline_task = asyncio.create_task(pipeline.connect())
try:
await asyncio.wait_for(pipeline_ready.wait(), timeout=15)
except asyncio.TimeoutError:
logger.error(f"[{session_id}] Pipeline failed to connect")
await websocket.send_json({"type": "error", "message": "Failed to connect to AI"})
pipeline_task.cancel()
return
# Forward audio/text from client to pipeline
async def forward_audio():
while pipeline and pipeline._connected:
try:
pcm16 = await asyncio.wait_for(audio_queue.get(), timeout=1)
await pipeline.send_audio(pcm16)
except asyncio.TimeoutError:
continue
except Exception:
break
async def forward_text():
while pipeline and pipeline._connected:
try:
text = await asyncio.wait_for(text_queue.get(), timeout=1)
await pipeline.send_text(text)
# Store in Honcho
if kira_memory.enabled and identified:
kira_memory.store_user_message(text)
except asyncio.TimeoutError:
continue
except Exception:
break
fwd_audio = asyncio.create_task(forward_audio())
fwd_text = asyncio.create_task(forward_text())
audio_buffer = bytearray()
conversation_history: list[dict] = []
try:
while True:
@@ -145,7 +143,7 @@ async def conversation_ws(websocket: WebSocket):
msg = json.loads(raw)
msg_type = msg.get("type", "")
# ── Identity ──
# ── Identity & Preferences ──
if msg_type == "identify":
user_id = msg.get("user_id", "").strip()
user_name = msg.get("name", "").strip()
@@ -159,16 +157,6 @@ async def conversation_ws(websocket: WebSocket):
kira_memory.ensure_peers(user_id)
kira_memory.ensure_session(session_id)
# Build memory context and update pipeline
if kira_memory.enabled:
try:
ctx = kira_memory.build_system_prompt_suffix()
if ctx:
pipeline._memory_suffix = ctx
memory_suffix = ctx
except Exception:
pass
await websocket.send_json({
"type": "identified",
"user_id": user_id,
@@ -176,40 +164,94 @@ async def conversation_ws(websocket: WebSocket):
})
continue
# ── Preferences ──
if msg_type == "set_preference":
key = msg.get("key", "").strip()
value = msg.get("value", "").strip()
if key and user_id and user_id != "default-user":
kira_memory.set_user_preference(user_id, key, value)
await websocket.send_json({
"type": "preference_saved",
"key": key,
"success": True,
})
continue
# ── Audio (PCM16) ──
# ── Conversation ──
if msg_type == "audio":
audio_b64 = msg.get("data", "")
if audio_b64:
pcm16 = base64.b64decode(audio_b64)
await audio_queue.put(pcm16)
continue
# Accumulate PCM16 audio chunks
chunk = base64.b64decode(msg["data"])
audio_buffer.extend(chunk)
# ── Text input ──
if msg_type == "conversation_text":
text = msg.get("text", "").strip()
if text:
await text_queue.put(text)
continue
elif msg_type == "transcribe":
if not audio_buffer:
await websocket.send_json({"type": "error", "message": "No audio data"})
continue
if msg_type == "ping":
logger.info(f"[{session_id}] Transcribing {len(audio_buffer)} bytes...")
# 1. STT
transcript = await transcribe_audio(bytes(audio_buffer))
audio_buffer.clear()
if not transcript:
await websocket.send_json({"type": "error", "message": "Could not transcribe"})
continue
await websocket.send_json({"type": "transcript", "role": "user", "text": transcript})
conversation_history.append({"role": "user", "content": transcript})
# 2. LLM
logger.info(f"[{session_id}] User: {transcript}")
kira_text = await run_conversation(transcript, user_id)
conversation_history.append({"role": "assistant", "content": kira_text})
logger.info(f"[{session_id}] Kira: {kira_text}")
# Store in Honcho
if kira_memory.enabled and identified:
try:
kira_memory.store_messages(transcript, kira_text)
except Exception:
pass
# 3. TTS
await websocket.send_json({"type": "speaking_start", "text": kira_text})
audio_bytes = await synthesize_speech(kira_text)
audio_b64 = base64.b64encode(audio_bytes).decode("utf-8")
await websocket.send_json({"type": "audio", "data": audio_b64, "text": kira_text})
await websocket.send_json({"type": "speaking_end"})
elif msg_type == "conversation_text":
user_text = msg.get("text", "").strip()
if not user_text:
continue
conversation_history.append({"role": "user", "content": user_text})
logger.info(f"[{session_id}] User (text): {user_text}")
kira_text = await run_conversation(user_text, user_id)
conversation_history.append({"role": "assistant", "content": kira_text})
logger.info(f"[{session_id}] Kira: {kira_text}")
if kira_memory.enabled and identified:
try:
kira_memory.store_messages(user_text, kira_text)
except Exception:
pass
await websocket.send_json({"type": "speaking_start", "text": kira_text})
audio_bytes = await synthesize_speech(kira_text)
audio_b64 = base64.b64encode(audio_bytes).decode("utf-8")
await websocket.send_json({"type": "audio", "data": audio_b64, "text": kira_text})
await websocket.send_json({"type": "speaking_end"})
elif msg_type == "ping":
await websocket.send_json({"type": "pong"})
except WebSocketDisconnect:
logger.info(f"[{session_id}] Disconnected")
except Exception as e:
logger.error(f"[{session_id}] Error: {e}")
finally:
fwd_audio.cancel()
fwd_text.cancel()
if pipeline:
await pipeline.disconnect()
if pipeline_task:
pipeline_task.cancel()
try:
await websocket.send_json({"type": "error", "message": str(e)})
except Exception:
pass