/interaction-latency

name: interaction-latency
description: Measure time from user tap to action completion. Use when tracking button response times, form submissions, add-to-cart, or any tap-triggered operation.
triggers:
  - "add to cart is slow"
  - "button feels slow"
  - "form submission timing"
  - "measure interaction latency"
  - "tap response time"
  - "track button performance"
priority: 2

Interaction Latency

Time from user tap to action successfully completed.

When to Use

• "Add to cart" button tapped → cart updated
• "Submit" button tapped → form processed
• "Like" button tapped → state changed
• Any tap that triggers async work

Measurement Pattern

TAP → START_SPAN → [async work] → END_SPAN

1. Capture tap timestamp 2. Start span with operation name 3. End span when action confirms success 4. Include success/failure outcome

Key Thresholds

| Rating | Duration | |--------|----------| | Good | <300ms | | Acceptable | <1s | | Poor | >1s |

Implementation

See `references/ui-performance.md` (Entry Point Latency section) for platform-specific code.

Common Mistakes

• Ending span on API call start (not completion)
• Not tracking failure cases
• Missing the tap timestamp (starting late)

Related Skills

• See `skills/navigation-latency` for screen-to-screen transitions (vs single-tap actions)
• Combine with `skills/user-journey-tracking` for friction detection on key interactions