diff --git a/engine/.env.example b/engine/.env.example
index 0d7ae7f..db4aa5a 100644
--- a/engine/.env.example
+++ b/engine/.env.example
@@ -1,53 +1,92 @@
-# Server Configuration
+# -----------------------------------------------------------------------------
+# Engine .env example (safe template)
+# Notes:
+# - Never commit real API keys.
+# - Start with defaults below, then tune from logs.
+# -----------------------------------------------------------------------------
+
+# Server
 HOST=0.0.0.0
 PORT=8000
+# EXTERNAL_IP=1.2.3.4
 
+# Backend bridge (optional)
 BACKEND_URL=http://127.0.0.1:8100
+BACKEND_TIMEOUT_SEC=10
+HISTORY_DEFAULT_USER_ID=1
 
-# Audio Configuration
+# Audio
 SAMPLE_RATE=16000
+# 20ms is recommended for VAD stability and latency.
+# 100ms works but usually worsens start-of-speech accuracy.
 CHUNK_SIZE_MS=20
+DEFAULT_CODEC=pcm
+MAX_AUDIO_BUFFER_SECONDS=30
 
-# VAD Configuration
+# VAD / EOU
+VAD_TYPE=silero
+VAD_MODEL_PATH=data/vad/silero_vad.onnx
+# Higher = stricter speech detection (fewer false positives, more misses).
 VAD_THRESHOLD=0.5
-VAD_EOU_THRESHOLD_MS=600
-VAD_MIN_SPEECH_DURATION_MS=160
+# Require this much continuous speech before utterance can be valid.
+VAD_MIN_SPEECH_DURATION_MS=100
+# Silence duration required to finalize one user turn.
+VAD_EOU_THRESHOLD_MS=800
 
-# OpenAI / LLM Configuration (required for duplex voice)
-OPENAI_API_KEY=sk-fc4d59b360475f53401a864db8ce0985010acc4e696723d20a90d6569f38d80a
-OPENAI_API_URL=https://api.qnaigc.com/v1  # Optional: for Azure or compatible APIs
-LLM_MODEL=deepseek-v3
+# LLM
+OPENAI_API_KEY=your_openai_api_key_here
+# Optional for OpenAI-compatible providers.
+# OPENAI_API_URL=https://api.openai.com/v1
+LLM_MODEL=gpt-4o-mini
 LLM_TEMPERATURE=0.7
 
-# TTS Configuration
+# TTS
+# edge: no SiliconFlow key needed
+# siliconflow: requires SILICONFLOW_API_KEY
 TTS_PROVIDER=siliconflow
 TTS_VOICE=anna
 TTS_SPEED=1.0
 
-# SiliconFlow Configuration (for TTS and ASR)
-SILICONFLOW_API_KEY=sk-thmzysdpqqmhqxxshyqoxvjeiflexjdgaftyufrsgrhpjnyx
+# SiliconFlow (used by TTS and/or ASR when provider=siliconflow)
+SILICONFLOW_API_KEY=your_siliconflow_api_key_here
 SILICONFLOW_TTS_MODEL=FunAudioLLM/CosyVoice2-0.5B
-
-# ASR Configuration
-ASR_PROVIDER=siliconflow
 SILICONFLOW_ASR_MODEL=FunAudioLLM/SenseVoiceSmall
+
+# ASR
+ASR_PROVIDER=siliconflow
+# Interim cadence and minimum audio before interim decode.
 ASR_INTERIM_INTERVAL_MS=500
 ASR_MIN_AUDIO_MS=300
+# ASR start gate: ignore micro-noise, then commit to one turn once started.
+ASR_START_MIN_SPEECH_MS=160
+# Pre-roll protects beginning phonemes.
+ASR_PRE_SPEECH_MS=240
+# Tail silence protects ending phonemes.
+ASR_FINAL_TAIL_MS=120
 
-# Duplex Pipeline Configuration
+# Duplex behavior
 DUPLEX_ENABLED=true
 # DUPLEX_GREETING=Hello! How can I help you today?
 DUPLEX_SYSTEM_PROMPT=You are a helpful, friendly voice assistant. Keep your responses concise and conversational.
 
-# Barge-in Configuration
-# Minimum speech duration (ms) to trigger interruption - filters out brief noises
-# Lower = more sensitive (50-100ms recommended), Higher = filters more noise
-BARGE_IN_MIN_DURATION_MS=100
-
-ASR_START_MIN_SPEECH_MS=100
-ASR_PRE_SPEECH_MS=320
+# Barge-in (user interrupting assistant)
+# Min user speech duration needed to interrupt assistant audio.
+BARGE_IN_MIN_DURATION_MS=200
+# Allowed silence during potential barge-in (ms) before reset.
+BARGE_IN_SILENCE_TOLERANCE_MS=60
 
 # Logging
 LOG_LEVEL=INFO
-LOG_FORMAT=text
+# json is better for production/observability; text is easier locally.
+LOG_FORMAT=json
 
+# WebSocket behavior
+INACTIVITY_TIMEOUT_SEC=60
+HEARTBEAT_INTERVAL_SEC=50
+WS_PROTOCOL_VERSION=v1
+# WS_API_KEY=replace_with_shared_secret
+WS_REQUIRE_AUTH=false
+
+# CORS / ICE (JSON strings)
+CORS_ORIGINS=["http://localhost:3000","http://localhost:8080"]
+ICE_SERVERS=[{"urls":"stun:stun.l.google.com:19302"}]