Routes every open order line that no open fulfillment order covers (manual warehouse pin, the channel routing rules, the channel's own fulfillment orders in the body, else default routing), one fulfillment order per route, reserves the open quantity in the same transaction, and answers the fulfillment orders it created (201 created). Nothing left to route: 200 unchanged, nothing written. Fulfillment orders disabled on the channel: 200 skipped. Held fulfillment orders (postage balance, test order, awaiting payment, manual) are born paused with the hold recorded. Send {} when there is nothing to add.

Scope: fulfillment:write, channel:write or admin. A permission group made before the Channel API scopes existed grants it as fulfillment-orders:manage.

Idempotency: send Idempotency-Key; a retry with the same key replays the first answer.

Rate limit: write class, 1,200 requests per minute per tenant by default (read class 6,000). Every response carries X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset; a refusal is 429 rate_limited with Retry-After.