Concepts
Drift
The four drift severity bands, what triggers each, and why an exchange-rate movement can never authorize a store write.
Drift is the gap that opens between what Paywall Parity expects and what is actually true — either because the economic data moved, or because someone changed a price in the store directly.
The bands
Classification is on the absolute change ratio:
| Change | Severity | Behaviour |
|---|---|---|
| below 5% | Ignored | Not recorded, not surfaced. |
| 5% – under 10% | Mild | Recorded. Visible in history. |
| 10% – 20% | Review | Recorded and surfaced for review. |
| above 20% | Significant | Recorded and surfaced prominently. |
The 5% floor is the same threshold recommendations use. Below it, the movement is indistinguishable from rounding and FX noise.
Store drift
If the expected price and the actual store price differ, that is store drift — someone edited the price in Play Console, or a deployment did not land as intended.
Store drift is only classified when both prices are in the same currency. A currency change is a different event entirely and is not expressible as a percentage, so it returns no drift rather than a misleading number.
Store drift alerts appear on the Recommendations page.
Economic drift
When refreshed economic observations move a market's target materially, the recalculation produces a new recommendation and supersedes any stale open recommendation for the same market and plan.
Superseding rather than accumulating matters: two competing open recommendations for the same market is a decision trap, and whichever one a reviewer happens to click is arbitrary.
Drift never writes
An economic movement produces a recommendation for a human to review. It cannot trigger a store change on its own, and there is no configuration that makes it do so.
This is a deliberate design constraint rather than a missing feature. Currency markets move every day; a system that repriced a global catalogue in response would be writing to your store constantly, on evidence that reverses within the week.
What is not implemented
- A dedicated historical drift page. Drift is currently visible only as in-app alerts, not as a browsable history.
- Post-rounding materiality thresholds, cooldown, and hysteresis. A market oscillating around a band boundary will currently re-alert each time it crosses.
- Opt-in email notification delivery.
- Separation of new-customer pricing from existing-subscriber cohorts.