Tie a Shopify B2B company to its Dynamics GP customer

**Objective:** Link the Shopify B2B company `{company-name}` to a Dynamics GP customer by writing the GP customer ID into the company's `external-id`. Use `{customer-id}` when it is given; otherwise find or create the GP customer.

**Step 1: Find the Shopify company**

Call `shopify-get-company` (Shopify server) with `name.contains` = `{company-name}`. If it matches more than one company, list them and stop. If the company already has an `external-id`, show it, check it with `dynamics-gp-get-rm-customer` (Dynamics GP server), and stop unless the user asks to replace it.

Call `shopify-get-company-location` (Shopify server) with `company-name` = the company's name for the city, province, country and phone, and `shopify-get-company-contact` (Shopify server) with `company-id` and `is-main-contact` = true for the main contact.

**Step 2: Find the Dynamics GP customer**

If `{customer-id}` is given, call `dynamics-gp-get-rm-customer` (Dynamics GP server) with `customer-id` = `{customer-id}`, passing `company` = `{gp-company}` when it is given. Otherwise call it with `customer-name.contains` set to the distinctive part of the company name, and present the candidates with their city and balance.

**Step 3: Confirm**

Show the user exactly what will happen: either "link to existing GP customer X" or "create GP customer X with these fields, then link". Wait for an explicit yes. Do not write anything before it.

**Step 4: Write**

Only if no GP customer exists and the user confirmed creating one: call `dynamics-gp-rm-customer-add` (Dynamics GP server) once, with `customer-id` (at most 15 characters, upper case, confirmed by the user), `customer-name`, and whatever of `city`, `state`, `country`, `contact-person` and `phone-1` Shopify supplied. Shopify does not return a street address or postal code here, so leave `address-1` and `zip-code` empty unless the user gives them.

Then call `shopify-update-company` (Shopify server) once, with `company-id` and `external-id` = the GP customer ID.

**Step 5: Confirm the link**

Re-read with `shopify-get-company` and `dynamics-gp-get-rm-customer` and report the company, the GP customer ID, and whether the customer was created or already existed.

**Rules & Guidelines:**

* The only write tools this prompt may call are `dynamics-gp-rm-customer-add` (Dynamics GP, at most once) and `shopify-update-company` (Shopify, at most once), both after confirmation.
* Do NOT call `dynamics-gp-rm-customer-update` or `shopify-update-company-location`. Never change the company name.

**Validation:**

* If `dynamics-gp-rm-customer-add` fails, stop and report the error; do not update Shopify.
* If `shopify-update-company` fails after the GP customer was created, say that the GP customer now exists unlinked, and give its ID.