function processMessage(message, contact) {
  // FIRST: Check for opt-out
  if (isOptOut(message.content)) {
    processOptOut(contact, message.channel)
    return sendOptOutConfirmation(contact)
  }

  // THEN: Normal processing
  return normalProcessing(message, contact)
}

OPT_OUT_KEYWORDS = [
  "STOP",
  "UNSUBSCRIBE",
  "CANCEL",
  "END",
  "QUIT",
  "STOPALL",
  "STOP ALL"
]

function isOptOut(message) {
  normalized = message.toUpperCase().trim()
  return OPT_OUT_KEYWORDS.includes(normalized) ||
         containsOptOutPhrase(message)
}

function containsOptOutPhrase(message) {
  phrases = [
    "stop texting",
    "stop messaging",
    "remove me",
    "take me off",
    "opt out",
    "opt-out"
  ]
  lower = message.toLowerCase()
  return phrases.some(p => lower.includes(p))
}

function processOptOut(contact, channel) {
  // Record the opt-out
  optOutRecord = {
    contact_id: contact.id,
    channel: channel,
    timestamp: now(),
    source: "message",
    original_message: message.content
  }
  saveOptOut(optOutRecord)

  // Update contact record
  contact.opt_out_status[channel] = true
  contact.opt_out_date[channel] = now()
  saveContact(contact)

  // Add to suppression list
  addToSuppressionList(contact.phone || contact.email, channel)

  // Cancel any scheduled messages
  cancelScheduledMessages(contact.id, channel)

  // Log for audit
  auditLog("OPT_OUT", contact.id, channel, now())
}

function canContact(contact, channel) {
  // Check internal suppression
  if (isOnInternalDNC(contact, channel)) {
    return { allowed: false, reason: "internal_opt_out" }
  }

  // Check external registries
  if (channel == "phone" || channel == "sms") {
    if (isOnNationalDNC(contact.phone)) {
      return { allowed: false, reason: "national_dnc" }
    }
  }

  // Check consent status
  if (!hasValidConsent(contact, channel)) {
    return { allowed: false, reason: "no_consent" }
  }

  // Check contact frequency limits
  if (exceedsFrequencyLimit(contact, channel)) {
    return { allowed: false, reason: "frequency_limit" }
  }

  return { allowed: true }
}

ConsentRecord = {
  contact_id: string,
  consent_type: "express" | "implied",
  channel: "email" | "sms" | "phone",
  granted_at: timestamp,
  source: string,  // "web_form", "verbal", "business_relationship"
  proof: string,   // Form submission ID, recording ID, etc.
  scope: string,   // What they consented to
  expires: timestamp | null
}

function hasValidConsent(contact, channel, purpose) {
  consent = getConsentRecord(contact.id, channel)

  if (!consent) return false
  if (consent.expires && consent.expires < now()) return false
  if (!scopeCovers(consent.scope, purpose)) return false

  return true
}

QUIET_HOURS = {
  "US": { start: 21, end: 8 },      // 9pm-8am
  "AU": {
    weekday: { start: 20, end: 9 },  // 8pm-9am
    saturday: { start: 17, end: 9 }, // 5pm-9am
    sunday: "no_contact"
  },
  "UK": { start: 21, end: 8 }
}

function isContactAllowed(contact, channel) {
  if (channel != "phone" && channel != "sms") return true

  local_time = getLocalTime(contact.timezone)
  region = contact.region

  hours = QUIET_HOURS[region]
  // ... check against current time
}

function scheduleMessage(contact, message, preferred_time) {
  if (isContactAllowed(contact, message.channel, preferred_time)) {
    return schedule(message, preferred_time)
  }

  // Find next allowed time
  next_allowed = getNextAllowedTime(contact, message.channel)
  return schedule(message, next_allowed)
}

[Company Name]: [Message content]

Reply STOP to unsubscribe

[Company Name]
[Physical Address]

You're receiving this because [reason].
Unsubscribe: [link]

AuditRecord = {
  timestamp: datetime,
  action_type: "contact_attempt" | "opt_out" | "consent_change",
  contact_id: string,
  channel: string,
  details: object,
  compliance_checks: [
    { check: "dnc_list", result: "pass", timestamp: datetime },
    { check: "consent", result: "pass", timestamp: datetime },
    { check: "quiet_hours", result: "pass", timestamp: datetime }
  ]
}