How stock reaches a channel
Yessort publishes a stock figure to each of the store's locations, for each variant listed there. The store displays what it is told; it is never asked what it thinks it has. That direction is fixed — see who owns your product data.
Sites map to the store's locations
A Shopify "Location" is a building, so it maps to a Yessort site, never to a Yessort location. You set these mappings up when you connect the store, and can change them afterwards in the channel's settings.
The figure sent for a variant at a given store location is your stock at the Yessort site mapped to it. Two sites mapped to two store locations are published separately, so the store can show stock per location the way you actually hold it.
A mapping can be ignored instead of pointing at a site. Nothing is published to an ignored location, and anything the store sends about it is dropped. This is the right choice for a location that has nothing to do with the stock Yessort manages.
If the store deactivates or deletes a location, Yessort stops publishing to it but keeps the mapping. Reactivating the location in the store restores it. That only affects the location on that channel — the same Yessort site carries on serving every other channel normally.
Yessort also notices locations you have never mapped. A newly discovered one is surfaced for a decision rather than guessed at: until you either map it or mark it ignored, no stock routes there.
Which figure is sent
The published figure is your own stock, plus any supply a counterpart has published to you for that variant.
This is the one place the two are added together. Your Available on the variants grid or a variant's detail page counts only your own stock — a counterpart's published supply shows alongside it as a separate figure and is never folded in. So the in-app figure and the storefront figure disagreeing is normal and correct, not a fault: the storefront always includes partner supply, the in-app figure never does.
What "Available" means, where sets out all three figures side by side.
The figure never goes below zero
What is published is floored at zero. If you are short, the store is told zero rather than a negative number — a shop cannot display minus four of something.
That flooring has a consequence worth understanding before it bites you: a shortfall is invisible on the storefront, so a channel can sell units you do not have. See how negative stock happens.
When it is sent
On a change to the stock behind it, and on a regular sweep that re-sends current figures regardless. The sweep is what makes the system self-correcting: if a push fails or something is edited in the store's admin, the next sweep sends the right number again.
Checks that look for differences between the two sides, and what they do about them, are covered in keeping stock in step.