Exercise 1: Classifying a Ninth Function — Possible Solution
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THE NEW FUNCTION
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    def get_order_history_for_user(user, orders):
        valid_orders = [o for o in orders if validate_order_items(o)]
        return f"History for user {user['id']}: {len(valid_orders)} valid orders"

It calls validate_order_items() (an Order-group function) inside a
loop, and also reads user['id'] directly - touching both domains, one
through a call and one through direct data access, exactly the two
kinds of coupling this chapter's own combined method checks for.

RUNNING THIS CHAPTER'S OWN COMBINED CLASSIFICATION
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    calls: {'validate_order_items'}
    touches_order: True | touches_user: True
    classification: BOUNDARY

The call graph alone already catches the Order-side coupling here
(unlike update_user_loyalty_points, where the Order-side coupling was
also caught by calls but the User-side coupling needed the data-access
check). The direct user['id'] read confirms the User side, and the
combined check correctly reports BOUNDARY.

WHY THIS FUNCTION IS GENUINELY A BOUNDARY FUNCTION, NOT A MISCLASSIFICATION
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"Show me this user's order history" inherently needs to know something
about the user (their id, to know whose orders to show) AND something
about orders (which ones are actually valid) - there's no way to
answer this question using only one domain's own data. This matches
this chapter's own reasoning for send_order_confirmation_email and
update_user_loyalty_points: a genuine boundary function usually reflects
a genuine cross-domain question, not a mistake in how the domains were
split.

WHY THIS WORKS AS AN ANSWER
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The new function is built to genuinely need both domains (not
artificially forced), classified using this chapter's own exact
combined method rather than a new one, and the result is verified
directly with both the call-graph and data-access components shown
separately before being combined.