Each channel's price is the one sent, else the listing's stored price, adjusted by the price list when one is named. At most 500 listings (variants x channels) per request; more is 400 validation_failed.

Scope: products:write, channel:write or admin.

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.