Explain a customer balance gap between Chargebee and NetSuite

**Objective:** Reconcile the outstanding balance for the customer with email {email} between NetSuite (the ledger) and Chargebee (billing), looking at invoices dated in the last {lookback-days} days (default 90).

**Step 1: Find the customer in NetSuite**

Call `netsuite-get-customer` with `email` set to {email}. If more than one customer matches, list them (internal-id, name, email) and stop. If none match, say the customer is missing from NetSuite and continue to Step 2. Note `internal-id`, `name` and `balance`. Then call `netsuite-get-aropenitem` with `customer` set to the name and list each open item (document-number, due-date, amount, amount-applied).

**Step 2: Find the customer in Chargebee**

Call `chargebee-get-customer` with `email` set to {email}. If more than one matches, list them and stop. If none match, report the customer as present in NetSuite and absent from Chargebee. Note `id` and `unbilled-charges`. Call `chargebee-get-invoice` with `customer-id` set to that `id` and `date.from` set to the start of the window, and keep invoices whose `amount-due` is above zero. Call `chargebee-get-subscription` with the same `customer-id` and report `total-dues`.

**Step 3: Compare and report**

Sum Chargebee `amount-due` and compare it with the NetSuite `balance`. Report both totals, the difference, and a table of open invoices on each side. Match invoices by Chargebee `id` or `po-number` against NetSuite `document-number`; flag open items present on only one side.

**Rules & Guidelines:**

* Tools whose names start with netsuite are on the netsuite server; tools whose names start with chargebee are on the chargebee server. Both servers must be connected.
* Read-only: never call any NetSuite add or update tool (for example `netsuite-add-invoice`, `netsuite-add-customerpayment`, `netsuite-update-invoice`, `netsuite-update-customer`). Chargebee has no write tools here. Report differences only; never fix them.
* Compare in one currency only; Chargebee gives `currency-code`. If it differs from NetSuite's, report both and do not convert.

**Validation:**

* If either side returns nothing, say which side and still report the other.
* If the totals differ, list the unmatched invoices that explain the gap and state any remainder as unexplained.