docs(07): capture phase context

.planning/phases/07-weight-unit-selection/07-CONTEXT.md

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+# Phase 7: Weight Unit Selection - Context
+
+**Gathered:** 2026-03-16
+**Status:** Ready for planning
+
+<domain>
+## Phase Boundary
+
+Users can select a preferred weight unit (g, oz, lb, kg) and all weight displays across the app reflect that choice. Weight input stays in grams. The setting persists across sessions.
+
+</domain>
+
+<decisions>
+## Implementation Decisions
+
+### Claude's Discretion
+- Unit selector placement (TotalsBar, settings page, or elsewhere)
+- Pounds display format (traditional "2 lb 3 oz" vs decimal "2.19 lb")
+- Precision per unit (decimal places for oz, kg)
+- Default unit (grams, matching current behavior)
+- How formatWeight gets access to the setting (hook, context, parameter)
+
+</decisions>
+
+<code_context>
+## Existing Code Insights
+
+### Reusable Assets
+- `formatWeight()` in `src/client/lib/formatters.ts`: Currently `Math.round(grams) + "g"` — single conversion point for all weight display
+- `useSetting(key)` hook in `src/client/hooks/useSettings.ts`: Fetches from `/api/settings/:key`, caches with React Query
+- `useUpdateSetting()` mutation: PUT to `/api/settings/:key`, invalidates query cache
+- Settings API already exists with get/put endpoints
+
+### Established Patterns
+- Settings stored as key/value strings in SQLite `settings` table
+- React Query for server state, Zustand for UI-only state
+- Pill badges for weight/price display on ItemCard and CandidateCard (blue-50/blue-400 for weight)
+
+### Integration Points
+- `formatWeight()` call sites (~8 components): TotalsBar, ItemCard, CandidateCard, CategoryHeader, SetupCard, ItemPicker, collection route, setup detail route
+- `formatPrice()` is in the same file — similar pattern, not affected by this phase
+- TotalsBar already imports `useTotals()` and `formatWeight` — natural place for a unit toggle
+
+</code_context>
+
+<specifics>
+## Specific Ideas
+
+No specific requirements — user gave full discretion. Standard gear app patterns apply (LighterPack-style toggle).
+
+</specifics>
+
+<deferred>
+## Deferred Ideas
+
+None — discussion stayed within phase scope
+
+</deferred>
+
+---
+
+*Phase: 07-weight-unit-selection*
+*Context gathered: 2026-03-16*