> Canonical: https://antifailure.dev/solutions/marketplaces > Queues, workers and dual-writes, exercised where the ordering actually varies. # Queues, workers, dual-writes, matching logic staging never reproduces. The twin includes workers and queues. Production webhooks are blocked. Impatient retries and multi-tab checkout become deterministic scenarios. Matching logic that depends on queue order will not show up if staging skips workers. - 01 listings.created web → queue - 02 matching.worker queue → worker - 03 api.partners.test worker → partner · denied Production partner hostnames never resolve. The attempt is ledgered. ## Services, queues, and workers are a dimension staging drops. - → Queues in the twin . Simulated streams so dual-writes and retries are visible. - → Webhook containment . Production partner webhooks are blocked and written to the attempted-effect ledger. - → Retry personas . Impatient users and API clients become deterministic scenarios. Matching that depends on queue order only shows up when workers run. ## Buyers, sellers, listings, and in-flight orders as a referential subset. - → Both sides of the market . Buyers and sellers restored together, so a match has something to match against. - → Run the workers . Matching, notify, and settle against clone-local queues. - → Contain partners . Each partner host carries its own mode in the manifest, so the ones the twin simulates and the ones it refuses are written down rather than assumed. - 01 buyer_18c in-flight joined ↔ seller_north - 02 buyer_44a active joined ↔ seller_helix - 03 buyer_09f long-tail miss no match - seller_north listing open joined ↔ buyer_18c 01 - seller_helix listing open joined ↔ buyer_44a 02 - order_992 join valid miss no match 03 ## Duplicate events, missed matches, and irreversible writes in the oracle. - → Rolling deploys . Old and new schema coexistence is exactly what a disposable twin is for. - → Duplicate events . Visible when workers actually run. - → Compare . The oracle diffs the twin's writes against the baseline run. ### Baseline ### Candidate Duplicate events and missed matches do not appear if staging skips the queue. - Load Traffic shaped like production's access log. Read - Side-Effect Firewall Partner webhooks stay captured. Read - All solutions Teams and jobs. Read ## Know what happens before you deploy. Create a disposable production twin for every risky change. Catch migration failures before they reach customers.