A limit judged only when the value is new or changed

The customer asks: Check a limit (an item's maximum discount, say) against the ceiling only when someone sets or changes it, not on every edit of the record

• Verdict: Ready, with limits (3)
• Door: Event feed · area: Documents and print › Numbering and checks on save
• Recipe: Reading iVendNext's events reliably
• Sample: none yet
• Checked: laptop 2026-10-16 · the feed client's changed, 2 tests · not run on a shop

What you build

Your service reads the record's events and judges the value only when it is new or differs from the last one it saw (changed in the kit's feed client), then flags it. Recipe section A value judged only when it changes.

Limits

• The save is not refused: the value is judged seconds later and flagged.
• POS LANE X row X59, P-RULES4, gives the save rule's limit an on change switch, so the save itself is refused, when it merges.
• A value edited twice between two reads of the feed is judged once.

Tell the customer

A new or changed value over the limit is flagged within seconds; existing records are not held up by unrelated edits.

What next

1. Tell the customer the 3 limits above, and write them into the proposal.
2. Follow the recipe: Reading iVendNext's events reliably.
3. Build and test it on your sandbox (request one if you have none; what is on it).
4. Run the checks: your own tests, the kit's checks and the money kit's release gate (testing and release).
5. Release through the customer's own release gate (14. Testing and release); an app other shops install goes through the App library.

Stop your service for a while and start it again: it must catch up from the event feed, missing nothing.

Related needs

• Change the limits and who is told in one settings page, not in each rule — Ready, with limits (3)
• Our app gets its own queue of what changed, with business labels — Ready, with limits (1)
• A code must follow our pattern — Ready, with limits (1)
• Documents numbered our way — Ready

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