# 02 - Architecture

## Local-first rule

SQLite is the runtime source of truth.
MariaDB is sync transport plus setup and migration tooling.

```text
browser -> Gin handlers -> SQLite
                        -> pending_changes
background sync <------> MariaDB
```

Rules:
- user CRUD must continue when MariaDB is offline;
- runtime handlers and pages must read and write SQLite only;
- MariaDB access in runtime code is allowed only inside sync and setup flows;
- no live MariaDB fallback for reads that already exist in local cache.

## Sync contract

Bidirectional:
- projects;
- configurations;
- `vendor_spec`;
- pending change metadata.

Pull-only:
- components;
- pricelists and pricelist items;
- partnumber books and partnumber book items.

Readiness guard:
- every sync push/pull runs a preflight check;
- blocked sync returns `423 Locked` with a machine-readable reason;
- local work continues even when sync is blocked.
- sync metadata updates must preserve project `updated_at`; sync time belongs in `synced_at`, not in the user-facing last-modified timestamp.
- pricelist pull must persist a new local snapshot atomically: header and items appear together, and `last_pricelist_sync` advances only after item download succeeds.
- UI sync status must distinguish "last sync failed" from "up to date"; if the app can prove newer server pricelist data exists, the indicator must say local cache is incomplete.

## Pricing contract

`local_pricelist_items` is the single source of truth for both prices and component catalog (lot_name + lot_category). There is no separate component catalog table.

Rules:
- `local_components` table has been removed; do not recreate it;
- component list for the configurator autocomplete comes from `local_pricelist_items` via `ListComponents`;
- quote calculation reads prices from `local_pricelist_items` only;
- latest pricelist selection ignores snapshots without items;
- auto pricelist mode stays auto and must not be persisted as an explicit resolved ID.

## lot_name case handling

lot_names in `local_pricelist_items` may be stored in mixed case in databases synced before normalization was enforced. `NormalizeLotName` (uppercase + trim) is applied at sync time via `PricelistItemToLocal`, but existing rows are not retroactively updated.

Rules:
- all SQLite queries that filter by `lot_name` must use `UPPER(lot_name) IN ?` or `UPPER(lot_name) = ?` with an uppercased input — never a bare `=` or `IN` on a string that may have been sourced from user input or a legacy row;
- result map keys must preserve the original case passed by the caller (build a `uppercase → original` index before the query);
- `GetLocalPricesForLots` is the canonical pattern: it uppercases the input list, queries with `UPPER(lot_name) IN ?`, and returns keys that match the input lot_names;
- frontend JS must never infer a component category from the lot_name prefix; `lot_category` from `local_pricelist_items` is the only valid source; items without a category fall into the "Other" tab.

## Pricing tab layout

The Pricing tab (Ценообразование) has two tables: Buy (Цена покупки) and Sale (Цена продажи).

Column order (both tables):

```
PN вендора | Описание | LOT | Кол-во | Estimate | Склад | Конкуренты | Ручная цена
```

Per-LOT row expansion rules:
- each `lot_mappings` entry in a BOM row becomes its own table row with its own quantity and prices;
- `baseLot` (resolved LOT without an explicit mapping) is treated as the first sub-row with `quantity_per_pn` from `_getRowLotQtyPerPN`;
- when one vendor PN expands into N LOT sub-rows, PN вендора and Описание cells use `rowspan="N"` and appear only on the first sub-row;
- a visual top border (`border-t border-gray-200`) separates each vendor PN group.

Vendor price attachment:
- `vendorOrig` and `vendorOrigUnit` (BOM unit/total price) are attached to the first LOT sub-row only;
- subsequent sub-rows carry empty `data-vendor-orig` so `setPricingCustomPriceFromVendor` counts each vendor PN exactly once.

Controls terminology:
- custom price input is labeled **Ручная цена** (not "Своя цена");
- the button that fills custom price from BOM totals is labeled **BOM Цена** (not "Проставить цены BOM").

CSV export reads PN вендора, Описание, and LOT from `data-vendor-pn`, `data-desc`, `data-lot` row attributes to bypass the rowspan cell offset problem.

## Configuration versioning

Configuration revisions are append-only snapshots stored in `local_configuration_versions`.

Rules:
- the editable working configuration is always the implicit head named `main`; UI must not switch the user to a numbered revision after save;
- create a new revision when spec, BOM, or pricing content changes;
- revision history is retrospective: the revisions page shows past snapshots, not the current `main` state;
- rollback creates a new head revision from an old snapshot;
- rename, reorder, project move, and similar operational edits do not create a new revision snapshot;
- revision deduplication includes `items`, `server_count`, `total_price`, `custom_price`, `vendor_spec`, pricelist selectors, `disable_price_refresh`, and `only_in_stock`;
- BOM updates must use version-aware save flow, not a direct SQL field update;
- current revision pointer must be recoverable if legacy or damaged rows are found locally.

## Sync UX

UI-facing sync status must never block on live MariaDB calls.

Rules:
- navbar sync indicator and sync info modal read only local cached state from SQLite/app settings;
- background/manual sync may talk to MariaDB, but polling endpoints must stay fast even on slow or broken connections;
- any MariaDB timeout/invalid-connection during sync must invalidate the cached remote handle immediately so UI stops treating the connection as healthy.

## Naming collisions

UI-driven rename and copy flows use one suffix convention for conflicts.

Rules:
- configuration and variant names must auto-resolve collisions with `_копия`, then `_копия2`, `_копия3`, and so on;
- copy checkboxes and copy modals must prefill `_копия`, not ` (копия)`;
- the literal variant name `main` is reserved and must not be allowed for non-main variants.

## Configuration types

Configurations have a `config_type` field: `"server"` (default) or `"storage"`.

Rules:
- `config_type` defaults to `"server"` for all existing and new configurations unless explicitly set;
- the configurator page is shared for both types; the SW tab is always visible regardless of type;
- storage configurations use the same vendor_spec + PN→LOT + pricing flow as server configurations;
- storage component categories map to existing tabs: `ENC`/`DKC`/`CTL` → Base, `HIC` → PCI (HIC-карты СХД; `HBA`/`NIC` — серверные, не смешивать), `SSD`/`HDD` → Storage (используют существующие серверные LOT), `ACC` → Accessories (используют существующие серверные LOT), `SW` → SW.
- `DKC` = контроллерная полка (модель СХД + тип дисков + кол-во слотов + кол-во контроллеров); `CTL` = контроллер (кэш + встроенные порты); `ENC` = дисковая полка без контроллера.
- the available config types and their localized names flow from `qt_settings.config_types` on the server;
  QF falls back to hardcoded "server/Сервер" and "storage/СХД" when the setting is absent.

## Server-driven configurator settings (`qt_settings`)

QF reads four settings from `qt_settings` (MariaDB) and caches them in `local_qt_settings` (SQLite).
They are synced during every component sync. See `bible-local/server-contract-qt-settings.md` for the
full contract and JSON schemas.

| Setting key | Effect in QF |
|-------------|-------------|
| `config_types` | New-config modal buttons; category allowlist per config type |
| `tab_config` | Configurator tab structure, sections, singleSelect |
| `always_visible_tabs` | Which tabs are shown even when empty |
| `required_categories` | Per-config-type badge on tabs with unfilled required categories |

Rules:
- sync runs as part of the pricelist pull; failure is non-fatal (Warn log only);
- `local_qt_settings` is a read-only cache — never written by user actions;
- absent or unparseable settings: QF uses hardcoded fallbacks for that key only;
- `config_types[].categories` is an allowlist: a category absent from all types is shown everywhere;
- `qt_categories.name` and `qt_categories.name_ru` are not used by QF runtime; do not depend on them.

## Vendor BOM contract

Vendor BOM is stored in `vendor_spec` on the configuration row.

Rules:
- PN to LOT resolution uses the active local partnumber book;
- canonical persisted mapping is `lot_mappings[]`;
- QuoteForge does not use legacy BOM tables such as `qt_bom`, `qt_lot_bundles`, or `qt_lot_bundle_items`.