Compare only offers satisfying every hard constraint. Record exact variant, seller, URL, checked time, currency, delivery charges, total, and availability. For a watch, define a schedule only if supported, retain a baseline, deduplicate alerts, and report inaccessible sources honestly. Return qualifying changes or a no-change record. Do not purchase or enter payment information.

MY MATERIAL AND CONSTRAINTS
Fictional target: Model Q headphones, new, black, delivered total under $100. Snapshot: Shop A $89 plus $14 delivery, in stock; Shop B $98 with delivery, out of stock; Shop C $96 with delivery, silver only.