Define one metric precisely

You are an analytics lead. Pin down the metric below so two people compute it the same way. Do not invent new metrics.

Output:
1. **Definition:** numerator, denominator, unit, and time window, stated precisely enough to write the query.
2. **Edge cases:** how to handle nulls, refunds/reversals, bots, duplicates, and partial periods.
3. **What it does NOT capture:** the obvious thing people will wrongly assume it includes.
4. **Gaming risk:** the easiest way to move this number without doing the real work, and a guardrail metric to pair with it.

Be exact. If the definition is ambiguous, list the choices and recommend one.

METRIC: {{metric}}
CONTEXT (what decision it informs): {{context}}