Phase 4 Stage 1: backend foundation (additive endpoints + schema)

Schema (idempotent migration):
- payment_sessions.is_free_trial -> is_first_session_discount (data copied)
- payment_sessions.mode TEXT NOT NULL DEFAULT 'chat' CHECK (chat|call)
- chat_sessions.topics TEXT[] for ESP picks (info-only)

New endpoints:
- GET /api/client/onboarding-state (drives verif sheet + S6 paywall gate)
- GET /api/client/chat-pricing (rewrite: chat+call groups + first-session
  discount block, per-customer eligibility)
- GET /api/shared/auth-providers (env-probed; replaces ENABLE_SOCIAL_AUTH
  build flag — frontend cutover lands in stage 2)
- GET /api/client/support-handles (Tanya Admin handles, CC-config-driven)

session_warning WS event fires once at 180s remaining.

app_config seeds (mock pricing tiers, first-session discount, support
handles, payment method order, end-session 2-step toggle).

CC SettingsPage: 3 new sections (first-session discount, pricing tiers
JSON editors, support handles).

15/15 Vitest passing. chat_sessions.is_free_trial also renamed for
consistency (plan only specified payment_sessions; pairing.service.js
read both).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/src/routes/public/client.payment.routes.js

@@ -7,11 +7,14 @@ import {
   getPaymentSession,
 } from '../../services/payment.service.js'
 import {
-  isCustomerEligibleForFreeTrial,
+  isCustomerEligibleForFirstSessionDiscount,
   isValidTier,
-  getPriceTiers,
+  findTier,
 } from '../../services/pricing.service.js'
-import { UserType } from '../../constants.js'
+import { getDb } from '../../db/client.js'
+import { UserType, SessionMode } from '../../constants.js'
+
+const sql = getDb()
 
 const resolveCustomer = async (request, reply) => {
   if (request.auth?.userType !== UserType.CUSTOMER) {
@@ -30,6 +33,25 @@ const resolveCustomer = async (request, reply) => {
   request.customer = customer
 }
 
+const readDiscountConfig = async () => {
+  const rows = await sql`
+    SELECT key, value FROM app_config
+    WHERE key IN (
+      'first_session_discount_enabled',
+      'first_session_discount_actual_price_idr',
+      'first_session_discount_duration_minutes',
+      'first_session_discount_modes'
+    )
+  `
+  const byKey = Object.fromEntries(rows.map((r) => [r.key, r.value?.value]))
+  return {
+    enabled: byKey.first_session_discount_enabled ?? true,
+    actual_price_idr: byKey.first_session_discount_actual_price_idr ?? 2000,
+    duration_minutes: byKey.first_session_discount_duration_minutes ?? 12,
+    modes: byKey.first_session_discount_modes ?? ['chat'],
+  }
+}
+
 /**
  * Payment session lifecycle (mocked — no Xendit yet).
  *
@@ -39,12 +61,13 @@ const resolveCustomer = async (request, reply) => {
  *   GET    /api/client/payment-sessions/:id
  */
 export const clientPaymentRoutes = async (app) => {
-  // Create a payment session (status = pending). Free-trial logic is server-side: if the
-  // customer is eligible AND this is NOT an extension, amount is forced to 0 and
-  // is_free_trial = true regardless of what the client passes.
+  // Create a payment session (status = pending). First-session-discount is server-authoritative:
+  // if the customer is eligible AND this is NOT an extension AND mode is in the configured
+  // modes list, amount is forced to the configured discount price.
   app.post('/', { preHandler: [authenticate, resolveCustomer] }, async (request, reply) => {
     const {
       duration_minutes,
+      mode = SessionMode.CHAT,
       targeted_mitra_id = null,
       is_extension = false,
     } = request.body ?? {}
@@ -55,33 +78,44 @@ export const clientPaymentRoutes = async (app) => {
         error: { code: 'VALIDATION_ERROR', message: 'duration_minutes must be a positive number' },
       })
     }
+    if (mode !== SessionMode.CHAT && mode !== SessionMode.CALL) {
+      return reply.code(422).send({
+        success: false,
+        error: { code: 'VALIDATION_ERROR', message: 'mode must be chat or call' },
+      })
+    }
 
-    // Free trial: never for extensions.
-    let isFreeTrial = false
+    let isFirstSessionDiscount = false
     let amount
 
     if (!is_extension) {
-      const eligible = await isCustomerEligibleForFreeTrial(request.customer.id)
+      const eligible = await isCustomerEligibleForFirstSessionDiscount(request.customer.id)
       if (eligible) {
-        isFreeTrial = true
-        amount = 0
+        const discount = await readDiscountConfig()
+        // Discount is mode-gated. With default config (modes: ['chat']) call-mode never
+        // gets the discount even if the user is eligible.
+        if (
+          discount.enabled
+          && discount.modes.includes(mode)
+          && duration_minutes === discount.duration_minutes
+        ) {
+          isFirstSessionDiscount = true
+          amount = discount.actual_price_idr
+        }
       }
     }
 
-    if (!isFreeTrial) {
-      // Resolve amount from the price tiers (duration-keyed). The client passes
-      // duration_minutes; we look up the matching tier to get the canonical price.
-      const tiers = await getPriceTiers()
-      const tier = tiers.find((t) => t.duration_minutes === duration_minutes)
+    if (!isFirstSessionDiscount) {
+      // Resolve amount from the configured tier list for the requested mode.
+      const tier = await findTier({ mode, durationMinutes: duration_minutes })
       if (!tier) {
         return reply.code(400).send({
           success: false,
-          error: { code: 'INVALID_TIER', message: 'No price tier matches the requested duration' },
+          error: { code: 'INVALID_TIER', message: 'No price tier matches the requested mode/duration' },
         })
       }
-      amount = tier.price
-      // Sanity check (defense-in-depth) — duration+price should match a known tier.
-      if (!(await isValidTier(duration_minutes, amount))) {
+      amount = tier.price_idr
+      if (!(await isValidTier({ mode, durationMinutes: duration_minutes, priceIdr: amount }))) {
         return reply.code(400).send({
           success: false,
           error: { code: 'INVALID_TIER', message: 'Invalid price tier selection' },
@@ -93,9 +127,10 @@ export const clientPaymentRoutes = async (app) => {
       customerId: request.customer.id,
       durationMinutes: duration_minutes,
       amount,
-      isFreeTrial,
+      isFirstSessionDiscount,
       isExtension: Boolean(is_extension),
       targetedMitraId: targeted_mitra_id || null,
+      mode,
     })
 
     return reply.code(201).send({
@@ -104,8 +139,9 @@ export const clientPaymentRoutes = async (app) => {
         id: session.id,
         amount: session.amount,
         duration_minutes: session.duration_minutes,
-        is_free_trial: session.is_free_trial,
+        is_first_session_discount: session.is_first_session_discount,
         is_extension: session.is_extension,
+        mode: session.mode,
         targeted_mitra_id: session.targeted_mitra_id,
         expires_at: session.expires_at,
         status: session.status,