Fix day↔week price conversion (6.99 weekly shows as 7.00)

[yusuftor]

Summary

A customer reported a 7-day £6.99 product showing weeklyPrice as £7.00 on the live paywall, while the StoreKit purchase sheet (and the paywall editor) correctly showed £6.99.

Root cause

Two compounding issues:

1. Approximate day↔week conversion. The computed-price logic converted days↔weeks via a 52/365 factor. But 52 weeks = 364 days, not 365 — so a 7-day period resolved to ~0.997 weeks instead of exactly 1.
2. SK2StoreProduct bypassed normalization. StoreKit sometimes reports a weekly subscription as .day × 7 rather than .week × 1. The SDK has SubscriptionPeriod.normalized() to collapse that to .week × 1, but SK2StoreProduct's price getters switched directly on the raw StoreKit period and never called it — so a weekly product hit the day↔week branch and 6.99 / 0.997 ≈ 7.009 truncated to 7.00.

Changes

• Exact day↔week conversion (7 days = 1 week) in all computed-price paths: the SubscriptionPeriod helper and the inline switches in SK2StoreProduct, APIStoreProduct, StripeProductType.
• SK2StoreProduct now routes through the normalized period. The four price getters (dailyPrice/weeklyPrice/monthlyPrice/yearlyPrice) were replaced with calls through the existing normalized subscriptionPeriod property and its pricePerDay/Week/Month/Year helpers. A StoreKit .day × 7 now collapses to .week × 1 before the math runs, so a weekly product's weekly price equals its price. This also removes the duplicated per-getter conversion logic.
• Month↔year was already exact (12); week↔month / week↔year stay as conventional approximations — those aren't whole-number relationships.
• SubscriptionPeriod.normalized() made internal for testability.
• Version bumped to 4.15.3 (Constants.swift, podspec, CHANGELOG).

Tests

SubscriptionPeriodPriceTests — 28 tests, incl. new coverage:

• weeklyPrice / dailyPrice for a 7-day period (pre-fix produced the penny-off value).
• 7-day vs 1-week consistency for both weekly and daily prices.
• Normalization: 7-day → 1 week, 14-day → 2 weeks, 3-day stays in days, and the full chain (7-day normalized → weeklyPrice equals the price).

SK2StoreProduct's getters can't be unit-tested directly (StoreKit.Product isn't constructible in tests); the normalization + helper tests cover the logic they now route through.

Test plan

• All unit tests pass
• Build passes
• swiftlint clean

Follow-up

APIStoreProduct and StripeProductType still carry their own inline conversion switches (now arithmetically correct). Consolidating all four product types onto the SubscriptionPeriod helper as the single source of truth would prevent this class of bug recurring per-file — worth a separate PR.

🤖 Generated with Claude Code

Greptile Summary

This PR fixes a penny-off price display bug where a 7-day £6.99 subscription showed weeklyPrice as £7.00. The root causes were an imprecise 52/365 day↔week conversion factor and SK2StoreProduct's price getters bypassing the existing normalized() function that collapses StoreKit's occasional .day × 7 encoding into .week × 1.

• Arithmetic fix: 52/365 replaced with exact 7 / 1/7 in SubscriptionPeriod, APIStoreProduct, and StripeProductType.
• Normalization fix: SK2StoreProduct's four inline price getters replaced with a single formattedComputedPrice helper routing through the normalized subscriptionPeriod property.
• Testability: normalized() promoted from private to internal for direct test access.

Confidence Score: 5/5

The change is safe to merge — it makes two well-scoped arithmetic corrections directly verified by the new tests.

Both fixes are narrow, independently testable, and the new test suite exercises the exact scenario that produced the original bug. The SK2StoreProduct refactor removes duplication rather than adding new logic paths.

No files require special attention. APIStoreProduct and StripeProductType still carry inline switches but are arithmetically correct after this PR.

Important Files Changed

Filename	Overview
Sources/SuperwallKit/StoreKit/Products/StoreProduct/SubscriptionPeriod.swift	Core fix: .week periodsPerDay changed from 365/52 to exact 7; .day periodsPerWeek changed from 52/365 to exact 1/7. normalized() promoted to internal for test access.
Sources/SuperwallKit/StoreKit/Products/StoreProduct/SK2StoreProduct.swift	Replaced four duplicated per-getter price switch statements with a single formattedComputedPrice helper routing through the normalized subscriptionPeriod property.
Sources/SuperwallKit/StoreKit/Products/StoreProduct/APIStoreProduct.swift	Inline day-week conversion constants corrected from 365/52 and 52/365 to exact 7 and 1/7.
Sources/SuperwallKit/StoreKit/Products/StoreProduct/StripeProductType.swift	Same arithmetic correction as APIStoreProduct for daily/weekly price inline switches.
Tests/SuperwallKitTests/StoreKit/Products/StoreProduct/SubscriptionPeriodPriceTests.swift	New tests cover: weekly price equality for 7-day period, 7-day/1-week consistency, daily price for 1-week period, and the full normalization chain.
CHANGELOG.md	4.15.3 entry added with accurate description of the computed price fix.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    SK2[SK2StoreProduct] --> FCP[formattedComputedPrice helper]
    FCP --> SP[subscriptionPeriod property]
    SP --> NRM[normalized: day x7 to week x1]
    NRM --> HELPER[pricePerDay / pricePerWeek / pricePerMonth / pricePerYear]
    HELPER --> MATH_W[.week: periodsPerDay = 7 x value EXACT]
    HELPER --> MATH_D[.day: periodsPerWeek = value / 7 EXACT]
    MATH_W --> ROUND[NSDecimalNumber rounding down scale 2]
    MATH_D --> ROUND
    ROUND --> OUT[Formatted price string]
    API[APIStoreProduct and StripeProductType] --> INLINE[Inline switches day-week now exact 7]
    INLINE --> ROUND

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[yusuftor]

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