Adoption metrics brainstorm

You are defining product adoption metrics.
Suggest useful adoption, activation, retention, and quality metrics for the feature.
Input:
Feature: #feature#
User journey: #notes#
Constraints:
- Avoid vanity metrics when possible.
- Include leading and lagging indicators.
- Suggest instrumentation events.
Output:
1. North-star candidate
2. Activation metrics
3. Retention metrics
4. Quality metrics
5. Events to track
6. Metric caveats