# F-082 — Architect: /inventory editable fields cannot be saved; Stock UX needs click-to-edit

## Root cause

Two views both have inline-edit affordances with subtle UX gaps:

### A) Standalone `/inventory` page (`apps/admin/src/app/(dashboard)/inventory/page.tsx`)
- **SKU** and **EAN** are already click-to-edit and save on blur/Enter via `handleSaveSku`/`handleSaveEan`. ✅
- **Stock** opens edit mode on click but the operator still has to click an **OK** button to persist. Cancel is via ✕. This violates the desired "save on blur or Enter" UX.

### B) `InventorySection.tsx` (inventory tab inside the product editor)
- **Precio neto**: opens via ✏️ pencil, saves via OK button (no Enter/blur save).
- **Stock**: opens via ✏️ pencil, saves via OK button.
- **SKU** and **EAN**: not editable at all (plain text in the table) — silent loss if anyone tries.

## Design

Standardise on **click-to-edit + save on blur/Enter** for every editable cell. Remove pencil icons and OK buttons where they exist. Pattern:

```
<button onClick={() => enterEdit(id)}>{value}</button>
   ↳ swaps to
<input autoFocus
       value={editValue}
       onChange={...}
       onBlur={() => save(id)}
       onKeyDown={e => { if (e.key === 'Enter') save(id); if (e.key === 'Escape') cancel(id); }}
       disabled={saving}
/>
```

### Files / changes

1. `apps/admin/src/app/(dashboard)/inventory/page.tsx`
   - Stock cell: drop the OK button and ✕ button. Save fires on blur and Enter; cancel on Escape restores the original stock value.
   - Existing `msg` indicator shows the save state.
   - SKU and EAN unchanged (they already work).

3. `apps/admin/src/features/products/components/sections/InventorySection.tsx`
   - **Stock**: replace ✏️ + OK + ✕ pattern with the same click-to-edit + save on blur/Enter pattern.
   - **Precio neto**: same — drop OK and ✕, save on Enter/blur.
   - **SKU**: add inline editing (was plain text). Click cell → input → save on blur/Enter → `productsApi.updateVariant(productId, variantId, { sku })`.
   - **EAN**: add inline editing (was plain text). Same mechanism; `null` when empty.
   - **IVA select**: stays as-is (already click-to-edit without explicit pencil).

### Persistence

All edits call existing PATCH endpoints:
- `productsApi.updateVariant(productId, variantId, { sku | ean })`
- `pricingApi.setVariantPrice(variantId, cents, vatRate)`
- `inventoryApi.setStock(variantId, qty)`

No new endpoints, no schema changes.

### Failure handling

- On API failure the existing inline `saveMsg` shows `Error`; cell reverts via `cancelEdit*` which restores the value from the row state.
- The previous value is held in state until the API response arrives so the cell can revert cleanly.

### Concurrency

A simple `saving` flag per cell disables the input and prevents double-submit. Last-write-wins on the backend (existing behaviour).

## Risk

Low. Pure UX refactor, no API contract change.

## Acceptance mapping
- "Every editable cell in /inventory saves on blur or Enter via PATCH /variants/:id" → all cells adopt the click-to-edit + onBlur/onKeyDown pattern.
- "Stock cell enters edit mode on a single click; the pencil icon is removed" → button value is the cell value; no pencil.
- "Successful save shows visual confirmation" → `msg` chip shows ✓.
- "Failed save shows inline error and restores the previous value" → saveMsg + cancelEdit path.
- "No regressions in the existing Prices tab or product editor" → changes scoped to InventorySection + /inventory page.
- "verify.sh is green" → typecheck + lint clean.