The situation
Two things needed to be true across the catalogue at all times: the storefront had to reflect real availability, and certain products had to be excluded from discount campaigns. Both were being maintained manually. Both drifted, because manual maintenance across thousands of variants always drifts.
The cost of drift is asymmetric and unpleasant: showing an out-of-stock item as available produces a cancelled order and an unhappy customer, while applying a discount to an excluded product costs margin on every sale until somebody notices.
What we did
Derived state instead of storing opinions. Availability is computed from the source of truth on a schedule and written to Shopify as structured metafields, which the theme reads directly. Nobody maintains a list.
Encoded the promotion rules. Discount-exemption is expressed as a rule applied to the catalogue rather than a flag somebody remembers to tick. When the rule changes, it changes in one place.
Ran it where it could be watched. The job runs on a fixed schedule on managed infrastructure, with output that makes it obvious whether the last run succeeded — because an automation nobody can inspect is an automation nobody trusts.
Why it mattered
This is the least glamorous category of work we do and, per hour, close to the most valuable. It removes a recurring manual task permanently, and it removes the error class that comes with it.
The test for whether an automation is worth building is simple: does someone do this every week, and does it go wrong when they’re on holiday?