---
phase: 02-dashboard-charts-and-layout
plan: 01
subsystem: ui
tags: [react, react-router, useSearchParams, select, lucide-react, i18n, dashboard, charts]

# Dependency graph
requires:
  - phase: 01-design-foundation-and-primitives
    provides: "Design tokens, PageShell, SummaryStrip, ChartEmptyState component"
provides:
  - "useMonthParam hook for URL-based month state"
  - "MonthNavigator component with prev/next arrows and month dropdown"
  - "i18n keys for chart labels and month navigation (EN + DE)"
affects: [02-02, 02-03, 03-collapsible-dashboard-sections, dashboard-page-refactor]

# Tech tracking
tech-stack:
  added: []
  patterns: [URL search param state via useMonthParam, locale-aware month formatting]

key-files:
  created:
    - src/hooks/useMonthParam.ts
    - src/components/dashboard/MonthNavigator.tsx
  modified:
    - src/i18n/en.json
    - src/i18n/de.json

key-decisions:
  - "MonthNavigator uses Select dropdown (not popover) for month jump -- consistent with existing form patterns"
  - "useMonthParam preserves other URL params via setSearchParams callback form"
  - "navigateMonth uses Date constructor for automatic year rollover"
  - "MonthNavigator accepts t prop but dropdown uses locale-aware Intl formatting"
  - "ChartEmptyState already existed from Phase 1 — skipped creation, added i18n keys only"

patterns-established:
  - "useMonthParam: URL state hook pattern using useSearchParams callback form to preserve other params"
  - "Month formatting: Date.toLocaleDateString with month:'long', year:'numeric'"

requirements-completed: [UI-DASH-01]

# Metrics
duration: 2min
completed: 2026-03-16
---

# Phase 02, Plan 01: Month Navigation and Chart Infrastructure Summary

**useMonthParam hook and MonthNavigator component for URL-based month selection, plus 10 new chart/navigation i18n keys in EN and DE**

## Performance

- **Duration:** ~2 min
- **Started:** 2026-03-16T12:01:18Z
- **Completed:** 2026-03-16T12:03:21Z
- **Tasks:** 2
- **Files modified:** 4

## Accomplishments
- useMonthParam hook reads/writes `?month=YYYY-MM` from URL with current month fallback and year-rollover-safe navigation
- MonthNavigator renders prev/next chevron buttons and a Select dropdown listing available budget months with locale-aware formatting
- Added 10 new i18n keys under `dashboard.*` for chart labels, month navigation, and empty states in both English and German

## Task Commits

Each task was committed atomically:

1. **Task 1: Create useMonthParam hook and MonthNavigator component** - `4481950` (feat)
2. **Task 2: Add chart and month navigation i18n keys** - `42bf1f9` (feat)

## Files Created/Modified
- `src/hooks/useMonthParam.ts` - Custom hook wrapping useSearchParams for month URL state with setMonth and navigateMonth
- `src/components/dashboard/MonthNavigator.tsx` - Prev/next arrow buttons + Select dropdown for month selection
- `src/i18n/en.json` - Added monthNav, noData, expenseDonut, incomeChart, spendChart, budgeted, actual, noBudgetForMonth, createBudget, generateFromTemplate keys
- `src/i18n/de.json` - German translations for all 10 new dashboard keys

## Decisions Made
- MonthNavigator uses the shadcn Select component (not a popover or custom dropdown) for month selection -- consistent with existing form patterns in the project
- formatMonthLabel uses `Date.toLocaleDateString(undefined, { month: "long", year: "numeric" })` for locale-aware month display rather than manual string formatting
- ChartEmptyState component was already created during Phase 1 scaffolding -- verified it matches the plan specification exactly, so no changes were needed

## Deviations from Plan

### Auto-fixed Issues

**1. [Rule 1 - Already Exists] Skipped ChartEmptyState component creation**
- **Found during:** Task 2 (ChartEmptyState and i18n keys)
- **Issue:** ChartEmptyState component already existed from Phase 1 setup
- **Fix:** Skipped creation, added only the i18n keys
- **Verification:** Component exists and exports correctly
- **Committed in:** 42bf1f9 (Task 2 commit)

---

**Total deviations:** 1 auto-fixed (1 already exists)
**Impact on plan:** No scope creep — component existed, only i18n work needed.

## Issues Encountered
None

## User Setup Required
None - no external service configuration required.

## Next Phase Readiness
- useMonthParam hook ready for consumption by DashboardPage refactor (Plan 03)
- MonthNavigator ready to be placed in PageShell action slot (Plan 03)
- ChartEmptyState ready for use in chart components (Plans 02)
- All chart i18n keys available for chart components (Plan 02)

## Self-Check: PASSED

- FOUND: src/hooks/useMonthParam.ts
- FOUND: src/components/dashboard/MonthNavigator.tsx
- FOUND: src/components/dashboard/charts/ChartEmptyState.tsx
- FOUND: commit 4481950
- FOUND: commit 42bf1f9

---
*Phase: 02-dashboard-charts-and-layout*
*Completed: 2026-03-16*