chore: complete v1.0 UI/UX Overhaul milestone

.planning/RETROSPECTIVE.md

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+# Project Retrospective
+
+*A living document updated after each milestone. Lessons feed forward into future planning.*
+
+## Milestone: v1.0 — UI/UX Overhaul
+
+**Shipped:** 2026-03-24
+**Phases:** 4 | **Plans:** 10 | **Tasks:** 19
+
+### What Was Built
+- OKLCH design system with two-tier category colors and semantic budget status tokens
+- Three chart types (expense donut, income bar, spend horizontal bar) with CSS variable theming
+- URL-based month navigation with MonthNavigator dropdown
+- Collapsible per-category dashboard sections with direction-aware diff and CSS animations
+- PageShell, StatCard, SummaryStrip shared components for consistent page structure
+- All 9 pages upgraded with consistent design, skeleton loading, and full i18n
+
+### What Worked
+- 4-phase dependency chain (foundation → charts → collapsibles → full-app) prevented rework
+- Research-first approach documented Recharts v3 patch and OKLCH patterns before planning
+- Pure presentational components (CategorySection, charts) made integration straightforward
+- Two-tier color approach (dark text, light fills) solved WCAG contrast without sacrificing aesthetics
+
+### What Was Inefficient
+- Plan 02-01 SUMMARY.md was never written, requiring retroactive artifact creation
+- Roadmap progress table fell out of sync (phases 3-4 completed but not marked in roadmap)
+- Divergence between local and remote branches required hard reset — lost v1.1 milestone work
+
+### Patterns Established
+- OKLCH two-tier pattern: ~0.55 lightness for text (WCAG), ~0.65-0.70 for chart fills
+- PageShell + skeleton pattern: every page gets PageShell header and matching skeleton
+- Direction-aware diff: SPENDING_TYPES array + isSpendingType() covers all 6 category types
+- Controlled collapsible state: parent owns open/close for smart defaults and month-change reset
+- Auth card accent: border-t-4 border-t-primary + favicon logo
+
+### Key Lessons
+1. Always verify remote state before starting new local work to avoid divergence
+2. Summary artifacts must be written immediately — retroactive creation loses context
+3. Roadmap progress tracking should be verified at milestone completion, not assumed correct
+
+### Cost Observations
+- Model mix: 100% quality profile (opus executors, sonnet verifiers)
+- Sessions: ~4-5 across the milestone
+- Notable: 10 plans across 4 phases completed in ~20 days with minimal rework
+
+---
+
+## Cross-Milestone Trends
+
+### Process Evolution
+
+| Milestone | Phases | Plans | Key Change |
+|-----------|--------|-------|------------|
+| v1.0 UI/UX | 4 | 10 | First GSD milestone on this project; research-first approach |
+
+### Top Lessons (Verified Across Milestones)
+
+1. Research before planning eliminates mid-phase surprises
+2. Foundation-first phasing (tokens → components → integration) prevents rework