Extract report builder routes to Next.js

[SakshiKekre]

Summary

• Extracts ReportBuilderPage and ModifyReportPage from the React Router catch-all to dedicated Next.js file-based routes ([countryId]/reports/create/ and [countryId]/reports/create/[userReportId]/)
• Migrates react-router-dom imports (useNavigate, useLocation, useParams) to the router abstraction layer (useAppNavigate, useAppLocation, prop passing)
• Converts location.state usage in ModifyReportPage to query params (?from=report-output&reportPath=...) for cross-router compatibility
• Updates the one caller (ReportOutput.page.tsx) that passes location.state to use query params instead
• Adds ModifyReportPageRoute bridge wrapper in CalculatorRouter so the Vite app continues to work via useParams

Dependent PR

#869 (report output extraction) is based on this branch. It will be merged into this branch before everything merges up to #851 → main. See #851 for the full merge strategy.

Route mapping

React Router path	Next.js route file
/:countryId/reports/create	calculator-app/src/app/[countryId]/reports/create/page.tsx
/:countryId/reports/create/:userReportId	calculator-app/src/app/[countryId]/reports/create/[userReportId]/page.tsx

Test plan

• cd calculator-app && bun run dev — navigate to /us/reports/create, create a report
• Navigate to /us/reports/create/<id> — verify modify page loads with report data
• Verify back breadcrumb navigates to reports list
• From report output, click "View setup" — verify query params (?from=report-output&reportPath=...) pass through and back navigation works
• cd app && VITE_APP_MODE=calculator npx vite — Vite dev server still works for both routes
• bun run test — all 2950 tests pass
• bun run lint — no errors
• bun run typecheck — passes (app + calculator-app)

[vercel]

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Project	Deployment	Actions	Updated (UTC)
policyengine-app-v2	Ready	Preview, Comment	Mar 25, 2026 11:18pm
policyengine-calculator	Ready	Preview, Comment	Mar 25, 2026 11:18pm
policyengine-website	Ready	Preview, Comment	Mar 25, 2026 11:18pm

[anth-volk]

Review findings — PR #862 (Extract report builder routes)

Code reviewer found no issues at confidence >= 80 — clean PR overall.

HIGH

1. Type safety regression: location.state → query params — ModifyReportPage previously received structured location.state ({ edit?: boolean; from?: string; reportPath?: string }). After migration to URL query params, all values are string | null — losing boolean typing for edit and structured typing for the others. The edit param is now compared as searchParams.get('edit') === 'true' which works but is fragile.

2. ModifyReportPageRoute bridge passes potentially-undefined userReportId — The bridge wrapper reads params.userReportId which is string | undefined from useParams, but ModifyReportPage uses it to fetch data. An undefined value would trigger a fetch for "" rather than showing an error.

MEDIUM

3. Stale useMemo dependencies — topBarActions in ModifyReportPage lists countryId, userReportId, and navigate in its dependency array, but none of these are used inside the memo callback. This causes unnecessary re-computations.

4. Missing/tampered query params cause misleading back-button behavior — If a user manually navigates to the modify page without query params (e.g., bookmarked URL), backPath and backLabel will be undefined, causing the back button to go to /reports instead of the report output. Not a bug per se, but a UX inconsistency worth noting.

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