What it does
Turns a business label into a counting contract two analysts would apply the same way: numerator membership, denominator eligibility, time rules, edge cases, checks, and what could get worse if the number became a target.
The skill proposes. An agent does not approve organizational meaning, and it does not silently edit an already approved definition.
When to reach for it
Type /define-metric, or ask in plain language.
Use it when “activation,” “active,” “revenue,” or “retained” would produce different SQL in two reasonable readings, or before anyone starts optimizing the number. Use grill-question when the decision and comparison are still unset. Use checked-analysis to compute a definition that is already agreed.
The counting contract
Specify numerator and denominator independently. For a proportion, every numerator member belongs in the eligible denominator. For a ratio of totals, do not substitute a mean of row-level ratios.
Name event time versus processing time, timezone, interval boundaries, cohort assignment, maturation, and late arrivals. Give a few include/exclude examples at the real ambiguity: midnight, two devices, a later refund, an immature cohort. If the metric will become a target, name a counter-metric and the mechanism, or write one sentence why none is needed.
Common questions
Does proposing a definition make it official? No. Status stays proposed until the responsible person approves it. Under the Engine, approval is a separate attestation bound to the file’s content hash.
What if an approved definition already exists? Preserve it. If the meaning must change, propose a new version rather than rewriting the approved file.
Do I need aftergrid installed? No. A definition can be a short document, a comment, or a dbt-style markdown file in the project. The Engine path adds versioning and hash-bound approval.
It's working if
- Two people could classify the same edge-case row the same way from the write-up.
- Time rules are explicit enough that a late-arriving event has a stated home.
- Rival interpretations were shown on a small example before one was chosen.
- Counter-metrics are named with a mechanism, or “none” has a sentence of reasoning — not a blank.
Where it fits
A Frame-stage standalone, often after grill-question and before plan-analysis. Neighbors: explore-data for source grain, learn-from-analysis when a later correction should become a proposed definition rather than folklore.