1 min lesson
The semantic / metric layer
Show why this lesson detail matters. "Without a metric layer, every team writes its own SQL for 'success rate,' and three dashboards disagree by lunch."
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The semantic / metric layerdefine once, agree everywhere
Without a metric layer, every team writes its own SQL for "success rate," and three dashboards disagree by lunch. A semantic layer defines each metric once, with its exact filter, denominator and sessionization, so every dashboard, alert and query resolves to the same definition. It kills the "whose number is right" debate that quietly drains trust.
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Full explanation
Full explanation
A metric defined once in the semantic layer, which every consumer inherits
metric: agent_success_rate description: Share of admitted agent runs that reach a success outcome source: agent_interactions entity: run_id # sessionized: one row per logical attempt filter: surface = 'agent' AND is_bot = false numerator: count(run_id) where outcome = 'success' denominator: count(run_id) # admitted attempts, includes censored = failure dimensions: [model, region, client_version, surface] owner: reliability-ds