sku and item fix

Backend/PROGRESS.md

@@ -4,6 +4,42 @@ Legend: `[ ]` not started · `[~]` in progress · `[x]` done
 Spec: `docs/10-BACKEND-PHASE1.md` (model + rules) · `docs/11-BACKEND-PHASE1.md` (API)
 Convention: `docs/01-DOC-GUIDE.md §6`. Update this file in the **same commit** as the code. When ticking `[x]`, append a short note + any deviation.
 
+## Per-variant content size (2026-08-11) — follow-up to the UOM re-model below
+
+The UOM re-model put `ContentQty`/`ContentUnit` on `Item` correctly, but the item **create page
+is a variant builder** and collected **one** form-level pair, copying it into every generated
+variant. Building "Coca-Cola in 500 ml / 1 L / 250 ml" produced three items all recorded as the
+same size — the exact case the builder exists for. The item contract already accepted a
+per-item pair, so the whole fix is in how values are captured.
+
+- **`ItemType.IsMeasurable`** (bool, default `false`) — set on Products → Item Types. A flagged
+  dimension's values are entered as a number + unit; the chip label, the SKU segment, the item
+  name and the stored content size all derive from that one pair. Unflagged dimensions are
+  unchanged free text, which is what an apparel `Size` (S/M/L) needs.
+- **`UpdateItemTypeRequest.IsMeasurable` is `bool?` and preserved when omitted.** A plain `bool`
+  binds an absent property as `false`, so the admin screen's name-only PUT would have cleared the
+  flag on every rename — the same bug class already recorded for `product-config` further down.
+- **The `BUILDER_ITEM_TYPES = ["color","size"]` hardcode is gone.** It had one consumer and had
+  become a live bug: a user-created "Pack Size" would be flagged measurable and then never
+  appear. Removal is behaviour-preserving on any current database (the seeder seeds exactly those
+  two names, and the fetch was already `status: Active`) and restores the documented contract
+  that users add their own types. Every Active item type is now offered; deactivation is the
+  intended remedy and the admin page already says so.
+- **SKU collision fixed before it could bite.** `skuSegment` strips the decimal point and
+  truncates to 3, so derived labels collided — `1.5L`/`15L` → `15L`, `500ml`/`500g` → `500`,
+  `2.5ml`/`25ml` → `25M`. Since the create loop is sequential and non-transactional, that would
+  have failed partway with `SKU_DUPLICATE` after creating some rows. Measurement segments now use
+  `measureKey`, which mirrors `ItemContent.Normalize` (L/Kg ×1000) and renders the point as `P`.
+- **Values dedupe on the normalised size, not the label** — `500 ml` and `0.5 L` read differently
+  but store identically, and `ItemContent.Normalize` is the server's notion of equality.
+- **At most one measurable dimension** per product: unchecked measurable types are disabled once
+  one is checked, re-checked at submit.
+- **The form-level pair survives as a fallback** — correct when the varying dimension isn't size —
+  and is hidden *and cleared* whenever a measurable dimension is active, so the two can never
+  disagree. Its validation is skipped in that mode, since its error message would otherwise be
+  invisible inside the hidden block.
+- The item **edit** page is untouched: one item, one size.
+
 ## UOM re-model (2026-08-11) — supersedes every "UOM conversion" note below
 
 Per-item UOM conversion is **gone**. Entries further down this file that describe
@@ -60,7 +96,7 @@ What replaced it:
 - [x] Warehouse + Bin (`/warehouses`, nested `/warehouses/{id}/bins`, bin code unique per warehouse)
 - [x] Item reorder settings (`PUT /items/{id}/reorder` full-replace upsert, warehouse-exists validation)
 - [x] Brand master (FR-MD-09) — CRUD + status + ETag; `Item.brandId` nullable FK
-- [x] Item Type master (FR-MD-10) — CRUD + status + ETag; **unreferenced by design**, feeds the builder dropdown only
+- [x] Item Type master (FR-MD-10) — CRUD + status + ETag; **unreferenced by design**. Feeds the builder's dimension list, and since 2026-08-11 carries `isMeasurable`, which decides whether its values are captured as free text or as a number + unit that becomes each item's content size (see the entry at the top of this file)
 - [x] SubCategory (FR-MD-04) — nested list/create under a category, `PUT`/`PATCH status` by id; `Item.subCategoryId` nullable FK, validated to belong to `categoryId`
 - [x] Product Configuration (FR-MD-11) — singleton `GET`/`PUT /product-config`; `CONFIG_DISABLED` gating on item writes
 - [x] Item **sale price** (FR-MD-01, 2026-07-22) — nullable `Item.SalePrice` (`numeric(18,4)`); on all Item DTOs (list/detail/create/update), validated `>= 0`. **Sales-only** — never enters GRN/FIFO/ledger. `null` ⇒ sell at stock value. Migration `AddItemSalePrice`. See the 2026-07-22 Done entry.