シートベースの請求

Total = Base price + (Seat add-on price × seat quantity)

Base plan:  $50/month
Seats:      8 × $10 = $80/month
────────────────────────────────
Total:      $130/month

Team Plan: $49/month (includes 5 seats)
Extra seats: $10/month each
8 total seats = $49 + (3 × $10) = $79/month

Per Seat: $12/month
5 users  = 5 × $12  = $60/month
50 users = 50 × $12 = $600/month

Starter:     $0/month   + $15/seat
Pro:         $99/month  + $10/seat
Enterprise:  $499/month + $7/seat

5-Seat Pack:  $50/month  ($10/seat)
10-Seat Pack: $80/month  ($8/seat)
25-Seat Pack: $175/month ($7/seat)

const session = await client.checkoutSessions.create({
  product_cart: [{
    product_id: 'pdt_team_plan',
    quantity: 1,
    addons: [{
      addon_id: 'adn_YOUR_SEAT_ADDON',
      quantity: 8  // 8 additional seats
    }]
  }],
  customer: { email: 'admin@company.com' },
  return_url: 'https://yourapp.com/success'
});

// Currently 3 seats → change to 8 seats
await client.subscriptions.changePlan('sub_123', {
  product_id: 'pdt_team_plan',
  quantity: 1,
  proration_billing_mode: 'prorated_immediately',
  addons: [{
    addon_id: 'adn_YOUR_SEAT_ADDON',
    quantity: 8  // new total, not +5
  }]
});

// Currently 8 seats → reduce to 3 seats
await client.subscriptions.changePlan('sub_123', {
  product_id: 'pdt_team_plan',
  quantity: 1,
  proration_billing_mode: 'prorated_immediately',
  addons: [{
    addon_id: 'adn_YOUR_SEAT_ADDON',
    quantity: 3  // new total
  }]
});

// Remove all additional seats, keep only base plan seats
await client.subscriptions.changePlan('sub_123', {
  product_id: 'pdt_team_plan',
  quantity: 1,
  proration_billing_mode: 'prorated_immediately',
  addons: []  // removes all add-ons
});

1. Credit   →  a portion of the OLD plan's price (base + all add-ons)
2. Charge   →  a FULL cycle of the NEW plan's price
3. Net      =  Charge − Credit

Plan:      $50/month base + $10/seat add-on
Current:   $50 + 3 × $10 = $80/month
New:       $50 + 8 × $10 = $130/month
Timing:    Day 15 of a 30-day cycle (50% remaining)

Current: $80/month → New: $130/month

Plan:      $50/month base, no add-ons
Change:    add 1 seat at $10/month
Timing:    Day 27 of a 30-day cycle (10% remaining)

Current:   $50 base + 8 × $10 seats = $130/month
New:       $50 base + 2 × $10 seats = $70/month
Timing:    Day 6 of a 30-day cycle (80% remaining)
Mode:      prorated_immediately

Credit for unused time on the current cycle (base plus all add-ons):
  = $130 × 80%
  = $104.00 credit

Charge for a full cycle at the new seat count:
  = $50 + (2 × $10)
  = $70.00

Net = $70.00 − $104.00 = −$34.00

→ $0 charged today
→ $34.00 held as subscription credit (applied to future renewals)
→ Billing cycle resets; next renewal is $70/month

{
  "immediate_charge": {
    "summary": {
      "settlement_amount": 9000,
      "settlement_currency": "USD"
    },
    "line_items": [
      {
        "type": "subscription",
        "unit_price": 5000,
        "quantity": 1,
        "proration_factor": -0.50
      },
      {
        "type": "addon",
        "unit_price": 1000,
        "quantity": 3,
        "proration_factor": -0.50
      },
      {
        "type": "subscription",
        "unit_price": 5000,
        "quantity": 1,
        "proration_factor": 1
      },
      {
        "type": "addon",
        "unit_price": 1000,
        "quantity": 8,
        "proration_factor": 1
      }
    ]
  }
}

const preview = await client.subscriptions.previewChangePlan('sub_123', {
  product_id: 'pdt_team_plan',
  quantity: 1,
  proration_billing_mode: 'prorated_immediately',
  addons: [{ addon_id: 'adn_YOUR_SEAT_ADDON', quantity: 8 }]
});

console.log('Charge today:', preview.immediate_charge.summary.settlement_amount);
console.log('Currency:', preview.immediate_charge.summary.settlement_currency);
// Show customer: "Adding 5 seats will cost $90.00 today"

Full Seats: $20/month - Full access to all features
View-Only Seats: $5/month - Read-only access
Guest Seats: $0/month - Limited external collaborator access

app.post('/webhooks/dodo', async (req, res) => {
  const event = req.body;

  switch (event.type) {
    case 'subscription.active': {
      // New subscription - provision seats
      const addonSeats = event.data.addons?.reduce(
        (total, addon) => total + addon.quantity, 0
      ) || 0;
      await provisionSeats(event.data.customer.customer_id, addonSeats);
      break;
    }

    case 'subscription.plan_changed': {
      // Seats changed - update access
      const newSeats = event.data.addons?.reduce(
        (total, addon) => total + addon.quantity, 0
      ) || 0;
      await updateSeatCount(event.data.subscription_id, newSeats);
      break;
    }

    case 'subscription.cancelled':
      // Subscription cancelled - deprovision
      await revokeAllSeats(event.data.subscription_id);
      break;
  }

  res.json({ received: true });
});

Full Seats:      $20/month - Full access to all features
View-Only Seats: $5/month  - Read-only access
Guest Seats:     $0/month  - Limited external collaborator access

const session = await client.checkoutSessions.create({
  product_cart: [{
    product_id: 'pdt_team_plan',
    quantity: 1,
    addons: [
      { addon_id: 'addon_full_seat', quantity: 10 },
      { addon_id: 'addon_viewer_seat', quantity: 25 },
      { addon_id: 'addon_guest_seat', quantity: 50 }
    ]
  }]
});

Monthly: $15/seat/month
Annual:  $12/seat/month (20% savings)

async function validateSeatCount(planId: string, seatCount: number) {
  const minimums = {
    'pdt_starter': 1,
    'pdt_team': 5,
    'pdt_enterprise': 25
  };

  if (seatCount < minimums[planId]) {
    throw new Error(`${planId} requires at least ${minimums[planId]} seats`);
  }
}