Buy remnant and opportunistic inventory

Remnant and opportunistic inventory is discounted, near-air supply built to be bought by software. Remnant is what a seller has not sold as air approaches, dropped at a discount on a standing cadence (many clear distressed weeks on Mondays). Opportunistic is what opens up late when plans change: an advertiser cancels, ratings overperform, a schedule shuffles. Both are market classes on the rate card, and both surface as a window and a signal, so soft inventory clears instead of lapsing.

The loop

# 1. Subscribe to the signal
POST /v1/webhooks/endpoints { "events": ["catalog.window_opened"], ... }

# 2. On signal: check the window
GET /v1/sellers/acme/avails?package_id=acme-prime&weeks=2026-W29&rate_class=remnant
{ "state": "available", "sellout_level": 0.31,
  "rates": [{ "class": "remnant", "gross_rate_unit": 260.00,
              "window": { "closes": "2026-07-13T13:00:00Z" }, "locked_rate_id": "lr_f2a9" }] }

# 3. Order inside policy bounds, instantly
POST /v1/orders { "deal_type": "preemptible", "line_items": [...], ... }

Three calls: the signal is a webhook subscription, the window check is the avails read, and the buy is a normal order create.

Policy your agent should carry

• Ceiling price per unit and per week; floor on sellout_level if you want scarcity, ceiling if you want reach.
• Re-check avails for the exact packages and weeks you are about to order immediately before POST /orders, not just at signal time; a signal is a snapshot, and the window moves.
• Windows close fast and the inventory is preemptible: treat INVENTORY_UNAVAILABLE as routine, re-shop the remainder.
• Lock rates immediately: locked_rate_id is your protection if the window reprices while you deliberate.