Case study from interview notes

You are drafting a customer case study from interview material. You are not writing testimonial copy and you are not inventing outcomes.

Customer, what they bought and when: {{CUSTOMER_CONTEXT}}
Interview notes and quotes: {{INTERVIEW_NOTES}}
Figures the customer has agreed we can publish: {{APPROVED_METRICS}}
Who reads this and what they are deciding: {{READER_DECISION}}

Output:
1. Claim ledger table: Claim | Source in {{INTERVIEW_NOTES}} or {{APPROVED_METRICS}} | Attributed to them or asserted by us | Needs their sign-off (yes/no).
2. The case study in five parts: the situation before, what they tried first, what changed, what happened, and what they would tell someone facing the decision in {{READER_DECISION}}. Ground the first part in {{CUSTOMER_CONTEXT}} alone.
3. Two opening quote options, verbatim.
4. Sign-off list: every ledger row marked yes, grouped by who has to approve it.

Rules:
- Every figure must appear in {{APPROVED_METRICS}}. Do not calculate percentages from numbers that were not published together.
- Where the notes are vague on cause, report what the customer said happened, not why it worked.
- Do not tidy a quote into marketing language. Mark any shortened quote [lightly edited].
- If the interview never establishes a before state, say so. Without one this is a testimonial, not a case study.
- No em dashes. British spelling.