See one honest sales trend across GP and Business Central

**Objective:** Give a single view of customer `{customer-id}` across both systems: the Dynamics GP history up to go-live on `{cutover-date}` and the Business Central activity since, starting from `{from-date}` (default 24 months before today).

**Step 1: Confirm the customer in both systems**

Call `dynamics-gp-get-rm-customer` with `customer-id` set to `{customer-id}`, and `business-central-get-customer` with `customer-number` set to `{customer-id}`. If one side has the customer and the other does not, say which, and continue with the side that has it. If neither has it, stop.

If `{cutover-date}` is empty, ask the user for the go-live date before continuing.

**Step 2: Read the GP history**

* Call `dynamics-gp-get-rm-sales-trx` with `customer-id`, `document-date.from` set to the start date and `document-date.to` set to `{cutover-date}`.
* Call `dynamics-gp-get-rm-trx` with `customer-id` and the same dates, leaving out voided documents, for invoices, credit memos and payments.

**Step 3: Read the BC activity**

* Call `business-central-get-posted-sales-invoice` with `sell-to-customer-number` and `posting-date.from` set to the day after `{cutover-date}`.
* Call `business-central-get-sales-transaction` with `sell-to-customer-number` for open orders and quotes.
* Call `business-central-get-detailed-customer-ledger` with `customer-number` and `posting-date.from` set to the day after `{cutover-date}`, for payments and credits.

BC entries posted on or before `{cutover-date}` whose document numbers match GP documents are the migrated opening balances, not new sales. Do not count them as BC activity.

**Step 4: Report**

* A header: customer name, GP salesperson, BC salesperson code, BC balance, BC credit limit.
* Sales by month, one line per month, each marked GP or BC, so the trend runs straight across go-live.
* Totals: GP sales before go-live, BC sales since, and the change in average monthly sales.
* Open BC orders and quotes, and open BC invoices with their due dates.
* Anything that changed at go-live: a different salesperson, payment terms or credit limit between the two systems.

**Rules & Guidelines:**

* `dynamics-gp-get-rm-customer`, `dynamics-gp-get-rm-sales-trx` and `dynamics-gp-get-rm-trx` are on the dynamics-gp server. `business-central-get-customer`, `business-central-get-posted-sales-invoice`, `business-central-get-sales-transaction` and `business-central-get-detailed-customer-ledger` are on the business-central server.
* This prompt is read-only. Do NOT call `business-central-update-customer`, `business-central-create-sales-order`, `business-central-create-sales-invoice` or `dynamics-gp-rm-customer-update`.
* If either system has more than one company, ask the user which GP company and which BC company to use before the first call, and pass them as `company`.

**Validation:**

* If GP has sales after `{cutover-date}`, report them separately as posted in GP after go-live; they may be missing from BC.
* If one side returns nothing for the period, report that side as having no activity rather than stopping.