Input
  |
  v
+--[ PII Fence ]--+  Hard reject: SSN, credit card, bank account,
|  PASS  |  BLOCK  |  driver license, passport patterns
+--------+---------+
  |
  v
+--[ Topic Fence ]-+  Redirect: politics, religion, legal,
|  PASS  |  BLOCK   |  investments, personal advice
+---------+---------+
  |
  v
+--[ Pricing Fence ]+  Route to human: discount requests,
|  PASS  |  ESCALATE |  free trials, price negotiation
+---------+----------+
  |
  v
+--[ Competitor Fence ]+  Reframe: competitor mentions,
|  PASS  |  REFRAME    |  force value-differentiation
+---------+-------------+
  |
  v
+--[ Promise Fence ]+  Soften: guarantees, certainties,
|  PASS  |  SOFTEN   |  enforce "typically see" language
+---------+----------+
  |
  v
  Quality Score (0-100) + Escalation Detection

Browser
  |
  POST /api/chat/prospect
  |
  +-- Rate limit check (per-IP)
  +-- Load brain content (cached: winning phrases, call patterns, ROI stories)
  +-- Load live sales metrics (win rate, avg MRR, top phrases)
  +-- Extract qualification slots from conversation history
  +-- Compute ROI if 3+ core slots filled (orders/week, AOV, commission)
  +-- Build dynamic system prompt (400+ lines):
  |     - Identity + conversation rules
  |     - 5-fence guardrail context
  |     - Qualification state + stage-specific instructions
  |     - Brain knowledge + playbook patterns
  |     - ROI data + calendar instructions
  |
  +-- Claude API (Haiku for early discovery, Sonnet for closing/tools)
  |     |
  |     +-- Tool calling loop (max 3 iterations):
  |           +-- check_availability -> computeAvailableSlots() -> Google FreeBusy
  |           +-- book_demo -> createBooking() -> Google Calendar event + Meet link
  |
  +-- Post-processing:
        +-- Extract qualification slots from response
        +-- Log conversation (PII-redacted)
        +-- Return: reply, suggested prompts, qualification state, ROI chart

Incoming Call (Twilio)
  |
  WebSocket (Twilio Media Stream)
  |
  +-- Deepgram STT (streaming, real-time)
  |     +-- Word timings -> WPM calculation -> pacing update
  |     +-- Confidence tracking -> quality monitoring
  |
  +-- Utterance Buffering (1500ms timeout for speech_final)
  |
  +-- Conversation Manager:
  |     +-- Update qualification slots (13 data points)
  |     +-- Check handoff triggers (frustration, pricing, high intent)
  |     +-- Detect contextual callback opportunities
  |     +-- Build voice system prompt (1-2 sentences, no formatting)
  |     +-- Claude API with calendar tools
  |     +-- Tool calling loop (HTTP to scheduling API, max 3 iterations)
  |
  +-- ElevenLabs TTS (streaming)
  |     +-- Dynamic speed matching prospect WPM
  |     +-- Filler audio if Claude latency > 400ms
  |     +-- Strategic pause after ROI reveal (1.5s)
  |
  +-- Barge-in Detection:
  |     +-- Stop TTS mid-sentence
  |     +-- Clear audio buffer
  |     +-- Capture prospect speech
  |     +-- Pass interrupted context to Claude
  |
  +-- Post-Call Processing:
        +-- Archive transcript
        +-- Extract patterns for brain learning
        +-- Create touchpoint

src/
  app/
    chat/page.tsx              # Chat page
    api/chat/prospect/route.ts # Chat API endpoint (880 lines)
    api/scheduling/            # Booking API endpoints
  components/
    prospect-chat/             # Chat widget component
  lib/
    ai.ts                      # Core AI engine (2,914 lines)
    guardrails.ts              # 5-fence guardrail system (683 lines)
    scheduling.ts              # Calendar booking engine
    google-calendar.ts         # Google Calendar integration
  voice-agent/                 # Separate PM2 process
    server.ts                  # Express + Twilio WebSocket (618 lines)
    conversation-manager.ts    # Voice AI brain (1,054 lines)
    stt.ts                     # Deepgram STT pipeline
    tts.ts                     # ElevenLabs TTS + filler cache
    handoff.ts                 # Warm transfer
    post-call.ts               # Post-call processing
    call-quality.ts            # Connection monitoring