What Skene catches

Five ways instrumentation breaks. Using PostHog examples here, Skene flags each one on the PR before it merges.

Removed events

A coding agent refactors a checkout function and the posthog.capture call goes with it.

- posthog.capture('checkout_completed', { plan: planId, value: amount })
  router.push('/thanks')

Skene flags the missing call and names the event that used to fire.

Renamed events

The agent tidies your event names. checkout_completed becomes checkoutCompleted, or order_placed, or vanishes into a constant.

- posthog.capture('checkout_completed', { plan, value })
+ posthog.capture('checkoutCompleted', { plan, value })

The funnel now splits across two names. Dashboards keep drawing from a name that no longer exists. Skene flags the rename and shows the old vs. the new.

Moved events

The capture call gets moved out of a conditional, into a different code path, or behind a feature flag. It still exists in the code, but no longer fires under the same conditions.

- if (user.isFirstPurchase) {
-   posthog.capture('first_purchase')
- }
+ posthog.capture('first_purchase')  // moved out of the guard

Skene tracks where in the control flow each event lives, so a moved call shows up as a change even when the call itself looks intact.

Altered payloads

A property gets renamed, dropped, or silently changes type from string to number. PostHog keeps accepting it. Funnels break in subtle ways.

  posthog.capture('signup', {
-   plan: 'pro',
+   plan_tier: 'pro',
-   referrer_id: id,
  })

Skene compares payload shapes call by call. Type changes, key renames, dropped properties all surface.

Conditional firing changes

The if-block guarding the event changes. The event still fires, just not under the same conditions. A retention metric quietly misses a slice of users.

- if (user.isActive && user.daysSinceSignup > 7) {
+ if (user.isActive) {
    posthog.capture('week_one_active')
  }

The condition collapsed; the call now fires for users who should not be counted. Skene flags conditional changes that affect when an event fires, not just whether the call exists.

What is next

• Install Skene: pick a surface and try it
• Supported libraries: which call shapes Skene reads
• Configuration: how to mark a change as accepted