Instrumentation Implementer Growth

instrumentation-implementer-growth

Agent: Growth Engineer

L2 growth engineer (Nx) responsible for growth instrumentation, metrics dashboards, funnel analysis, and growth loop activation.

Department ethos: ideal-data-growth.md

Skill Description

The growth instrumentation implementer translates the growth instrumentation spec into working tracking code, implementing acquisition, activation, and retention events alongside A/B test variant assignment and goal events so that every growth experiment produces measurable results.

When to Use

• When the growth instrumentation spec is approved and ready for implementation.
• When a new growth experiment requires variant assignment tracking and goal event instrumentation.
• When existing growth tracking has gaps that block funnel analysis or significance tracking.
• When a growth loop is being activated and needs node-level event instrumentation.

Workflow

1. Review the growth spec: Read the instrumentation spec for growth-specific events — channel attribution, signup source, onboarding step completion, activation event, referral actions, and experiment events.
2. Implement experiment instrumentation: For each A/B test, add variant assignment events (experiment_assigned with experiment_id, variant_id, user_id) and goal events (the conversion action being measured).
3. Implement funnel events: Add tracking at each growth funnel step — landing page view, signup started, signup completed, onboarding step N, activation event. Include channel attribution properties (UTM parameters, referrer).
4. Implement loop events: For growth loops, add events at each node — trigger impression, trigger action, invite sent, invite opened, referred signup, referred activation.
5. Add segmentation properties: Attach experiment variant, acquisition channel, and cohort properties to all events for downstream segmentation.
6. Submit for verification: Deploy to dev/staging and hand off with a verification checklist mapping each event to its test scenario.

Anti-Patterns

• Missing variant assignment events: Implementing goal events without variant assignment makes it impossible to attribute results to experiment arms. Why: without knowing which variant each user saw, the experiment data is useless.
• Hardcoded UTM values: Setting channel attribution to static values instead of reading from URL parameters corrupts channel-level analysis. Why: every user appears to come from the same channel, making CAC-per-channel uncomputable.
• No experiment_id on goal events: Firing generic goal events without linking to the experiment_id creates ambiguity when multiple experiments run simultaneously. Why: the same conversion event may be a goal for multiple experiments; the experiment_id enables correct attribution.

Output

Success:

• Growth tracking code deployed to dev/staging with all spec-defined events firing at correct trigger points, experiment instrumentation complete, and a verification handoff checklist.

Failure:

• Events fire with incorrect variant assignment, missing UTM properties, or wrong experiment_id. Report the discrepancies and the fixes required.

Related Skills

• instrumentation-spec-growth -- the spec that this skill implements.
• instrumentation-verifier-growth -- verifies the implementation in dev/staging.
• instrumentation-implementer-data -- the data analyst's implementer handles product instrumentation; this skill focuses on growth-specific events.