Inventory Stock Sync Agent

What is the Inventory Stock Sync Agent?

Selling the same products on a Shopify store, a WooCommerce site and eBay means keeping several stock counts in step by hand — and the day one of them drifts, you oversell. The Inventory Stock Sync Agent takes one store as the truth, keeps the others at its quantities every hour, and tells you about every SKU it could not settle.

You choose a master store and one or more target stores. For every SKU of the master, the agent works out the quantity each target should hold, compares it with what the target actually holds, and — depending on the mode — reports the difference, records the change it would make, or sets the target quantity and reads it back to confirm it.

The rule is deliberately simple:

target quantity = master quantity − safety stock (never below zero)

The safety stock is a number of units kept back per target, zero by default. There is no rules engine, no percentage split and no per-channel allocation: this agent replicates one authoritative stock, and that is all it does.

What it is, and what it is not

This is not an omnichannel stock engine. The master is the only source of truth. A target never influences the master, and two targets never influence each other. If a target sells on its own, its stock diverges from the master until the next run — the agent then sets it back to the master's quantity; it does not subtract the sale from the master.

If your warehouse system, your ERP or one of your stores is where stock is actually managed, make that store the master. If no single place holds the truth, this agent is not the right tool yet.

Which stores are supported?

The master and the targets can each be:

• Shopify — stock is read and set at one location you choose.
• WooCommerce — simple products, and the variations of variable products that manage their own stock.
• eBay — the inventory items of your seller account, by SKU.

The same provider can be used for the master and a target (two Shopify stores, say), and two targets can be of the same provider — or two locations of one Shopify store. A store cannot be its own target at the same location, and the same destination cannot be listed twice.

Two agents that write cannot target the same stock, and two writers cannot each target the other's master: the second configuration is refused, naming the first. An agent in Monitor mode writes nothing, so any number of them can watch the same stores.

Three modes

Every agent starts in Monitor. Switching to Auto is the one setting that lets the agent change something at a store on its own, and the screen says so in red where you make that choice.

Matching is by SKU, exactly

A master SKU is matched to a target item by exact SKU and nothing else. There is no matching by title, no "close enough", and no AI anywhere in the process. When the match is not clean the agent reports it and never guesses:

• a SKU the target does not carry is SKU_NOT_FOUND;
• a SKU that names two items on one side is SKU_AMBIGUOUS — nothing is written until the catalogue is fixed;
• a product without a SKU on the master is counted and skipped;
• a WooCommerce variable product is not stockable itself: its stock lives on its variations, which are matched by their own SKUs;
• an archived or trashed product is not for sale and is skipped;
• a target item that does not track stock is NOT_TRACKED — the agent never switches tracking on for you.

Locations

A Shopify store with several locations holding stock must be told which one the agent reads or writes. The agent never sums locations and never picks one for you: until you choose, it waits in "setup required" and says so. A store with a single location needs no choice.

Guard-rails

A wrong master reading — a connection pointed at the wrong store, a location that was just emptied, an import that zeroed a catalogue — would otherwise be replicated to every target within the hour. So every automatic write passes through guard-rails, and each one turns the write into a WRITE_BLOCKED case instead of performing it:

The defaults are conservative on purpose, and you can change them per agent.

Concurrency, honestly

A sale can land on a target between the moment the agent reads it and the moment it writes. On Shopify the write carries the quantity that was read, and Shopify refuses it if the level moved in between. WooCommerce and eBay offer no such check: the write goes through and the read-back catches the difference as WRITE_MISMATCH. The window is a few hundred milliseconds. If a target sells at high volume, prefer Approval mode, or accept that a mismatch is re-evaluated an hour later.

How does the agent run?

• Automatically, once per hour. The whole catalogue is compared each time; nothing is assumed from a previous run.
• On demand too, from the agent's page or from ChatGPT.
• Not in real time. There is no webhook: a sale at 10:05 is replicated during the 11:00 run.

A run reads up to 100,000 stockable items per connection by default. A larger catalogue is reported as truncated rather than partly synced in silence, and a run that reaches its time budget stops cleanly and lets the next run finish.

Exceptions are cases, not alerts

Every result other than SYNCED and UPDATED is a case about one SKU at one target. The same difference seen every hour is one case with a count; when a later run finds the target back in step — because it was written, or because you fixed it by hand — the case closes itself and says so.

Each case carries the SKU, both stores, the target's location when it has one, both quantities, the quantity the agent wanted, the action, the result and the reason in a sentence: enough to understand it without opening either store.

Approving proposed changes

In Approval mode every difference becomes a proposal. You approve or reject each one from ChatGPT or through the API, one at a time or up to 25 at once, and get one answer per proposal.

An approval is for the exact change you were shown. Before writing, the agent reads the master and the target again, recomputes the quantity with your current safety stock and re-applies the guard-rails. If a stock moved in between, nothing is written: the proposal is marked stale and a fresh one replaces it. Approving the same proposal twice writes nothing the second time, and a rejection holds in every mode until the master or the target stock moves.

What a run did, later

What one run decided — every SKU, both quantities, the quantity wanted, the quantity read back after a write, the result and the reason — is kept as that run's own record for 30 days, and does not change afterwards. After 30 days the record says so, rather than showing an empty list.

Reviewing results in Excel and on the web

The agent's page shows where every SKU stands and what each run did. Four live views are available, in the web workspace and as a connected Excel workbook:

• Current stock sync — one row per SKU and target: master and target quantities, the desired quantity, the quantity read back after a write, the action, the result and the reason.
• Open exceptions — the cases that need you.
• Runs — one row per run: SKUs checked, in sync, updated, proposed, blocked and failed.
• Historical run detail — the rows of one specific run, kept for 30 days.

Asking ChatGPT or Claude

With LinkyFlow connected to ChatGPT, Claude or any MCP client:

Set up my stock sync: master "EU boutique", target "Outlet" with a safety stock of 2, in monitor mode.

Run my stock sync now.

Which SKUs are out of sync?

Show me the blocked writes and why.

Switch my stock sync to auto mode.

The last one is a real change at your target stores, and the assistant tells you so before it is made.

Current limitations

• One master, one or more targets, one direction. It replicates an authoritative stock. It does not merge sales from several channels and does not subtract a target's sales from the master.
• Exact SKU only. No matching by title, barcode or similarity.
• One location per connection. Locations are never summed.
• The only write is a stock quantity. Products, prices, titles, listings and orders are never touched.
• Hourly, with no webhook.
• Approving and rejecting proposals is done from ChatGPT or the API for now, not from buttons on the agent's page.
• Detailed run data is kept for 30 days. Run summaries and the current sync stay.

Next steps

• Connect Shopify
• Connect WooCommerce
• Connect eBay