Consistent renewal date format + always show the live next renewal

[saikumarbt]

• formatSubscriptionDateTime now renders "MMM D, YYYY" (e.g. "Jun 8, 2026"), matching the "Started on" field and removing MM/DD ambiguity.
• Subscription detail computes the next renewal live via getNextRenewal (rolling a passed date forward) instead of showing the raw stored value, so the displayed date and the countdown always agree and never show a stale/past date.
• Add exhaustive next-renewal tests for every billing cycle (weekly → annual + custom), plus started-today and future-start cases.

Note: for a sub started 2026-06-08 (monthly) viewed on 2026-07-13, the next renewal is correctly 2026-08-08 — the 07-08 charge has already passed.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: a05b7019-1eea-45ce-adfe-7c04a58a5472

📥 Commits

Reviewing files that changed from the base of the PR and between 22de40e and dc9328c.

📒 Files selected for processing (4)

• __tests__/billing.test.ts
• __tests__/utils.test.ts
• app/subscriptions/[id].tsx
• lib/utils.ts

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Summary by CodeRabbit

• New Features

  • Subscription details now show the next renewal date and countdown based on the current billing cycle.

• Bug Fixes

  • Renewal dates now roll forward correctly when a subscription’s original date has passed.
  • Renewal date and countdown displays now stay synchronized.

• Style

  • Dates now use a clearer month-name format, such as “Mar 20, 2026.”

Walkthrough

The subscription detail screen now computes next renewal dates and countdowns from live subscription data. Date formatting uses month names, and tests cover renewal roll-forward behavior across billing cycles and updated display formatting.

Changes

Renewal display flow

Layer / File(s)	Summary
Live renewal calculation and display app/subscriptions/[id].tsx, __tests__/billing.test.ts	The screen calculates and displays the computed next renewal and countdown, while tests cover past, current, and future subscription starts across billing cycles.
Subscription date formatting lib/utils.ts, __tests__/utils.test.ts	Valid dates now use MMM D, YYYY formatting, with the updated output covered by tests.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant SubscriptionScreen
  participant getNextRenewal
  participant dayjs
  SubscriptionScreen->>getNextRenewal: subscription renewal/start/billing-cycle inputs
  getNextRenewal-->>SubscriptionScreen: nextRenewal
  SubscriptionScreen->>dayjs: compare renewal startOf("day") with today
  dayjs-->>SubscriptionScreen: daysLeft
  SubscriptionScreen-->>SubscriptionScreen: render next renewal and countdown

Loading

Poem

A rabbit hops through dates anew,
Rolling renewals into view.
“Mar 20” shines where numbers lay,
Cycles march from day to day.
The countdown thumps—hip hop, hooray!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the two main changes: renewal date formatting and live next-renewal display.
Description check	✅ Passed	The description accurately matches the changeset and explains the formatting, live renewal logic, and added tests.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch renewal-date-display

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