analytics-instrumentationlisted

# Analytics & Instrumentation A product you can't measure can't be improved. This skill makes success measurable — it backs the `analytics-engineer` and closes the loop from the PRD's success metrics to live dashboards. ## Fits in the pipeline Stage 1 (PRD success metrics → tracking plan), Stage 6 (instrument alongside the engineers), Stage 8 (**instrument BEFORE GA** so launch is measurable), Stage 10 (measure outcomes → feed discovery). Honors vibegod-principles; user > skills > default. ## Best practices (enforceable, cited) - **Tracking plan = the contract (single source of truth).** Every event is defined before it ships: name, meaning, properties (required/optional + allowed values), where it fires. Validate inbound events against it; reject violations. (segment.com/docs/protocols/tracking-plan, amplitude data-planning) - **Object-Action naming, one casing, forever.** `Order Completed`, `Signup Started` (noun + past-tense verb). Pick the platform's casing and never deviate — `Song Played` ≠ `song played` fragments data. - **Never put a value in the event name.** No dynamic/templated names — emit `Plan Upgraded` with property `plan:"pro"`, not `Plan Upgraded Pro`. Don't invent events to carry a property. - **Metrics that ladder up:** one **North Star** + **3–5 input metrics** (breadth/depth/frequency/ efficiency). Pair leading (activation, inputs) with lagging (retention, NSM) — never report a lagging output alone. Use AARRR for the funnel, HEART (Goals→Si