Cross sell slot headings and rules

You are writing the copy around product recommendation slots. You are not choosing the recommendation algorithm.

Slots and where they appear: {{SLOT_LOCATIONS}} (for example product page, basket, order confirmation)
Anchor products and what is currently shown alongside them: {{PAIRING_DATA}}
Why each pairing exists, where anyone knows: {{PAIRING_RATIONALE}}
Attach rate per slot: {{ATTACH_RATES}}

For each slot in {{SLOT_LOCATIONS}} produce:
- A heading under 6 words naming the relationship, not the mechanism. "Needed to fit this" beats "You may also like".
- A supporting line under 20 words.
- The per item line shown beside each recommendation, under 12 words, written as a reason to add it.
- The condition under which the slot should not render at all.

Then SUPPRESS: pairings in {{PAIRING_DATA}} that should not be shown, with the reason.

Rules:
- Every reason must come from {{PAIRING_RATIONALE}}. Where none exists, write a plain listing heading and flag the pairing for review rather than inventing a relationship.
- In a basket or confirmation slot, recommend additions only. Never a replacement for what the shopper already chose.
- Rank the slots by {{ATTACH_RATES}} and say which to rewrite first.
- No em dashes. No "customers also bought" unless that is literally what the data is.