Deep dive: Account, Stock, Sale, Purchase — +800 LOC business logic

Account:
- Multi-currency: company_currency_id, amount_total_signed
- Lock dates on res.company (period, fiscal year, tax) + enforcement in action_post
- Recurring entries: account.move.recurring with action_generate (copy+advance)
- Tax groups: amount_type='group' computes child taxes with include_base_amount
- ComputeTaxes batch function, findTaxAccount helper

Stock:
- Lot/Serial tracking: enhanced stock.lot with expiration dates + qty compute
- Routes: stock.route model with product/category/warehouse selectable flags
- Rules: stock.rule model with pull/push/buy/manufacture actions + procure methods
- Returns: action_return on picking (swap locations, copy moves)
- Product tracking extension (none/lot/serial) + route_ids M2M

Sale:
- Pricelist: get_product_price with fixed/percentage/formula computation
- Margin: purchase_price, margin, margin_percent on line + order totals
- Down payments: action_create_down_payment (deposit invoice at X%)

Purchase:
- 3-way matching: action_create_bill now updates qty_invoiced on PO lines
- Purchase agreements: purchase.requisition + line with state machine

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

addons/product/models/product.go

@@ -198,19 +198,63 @@ func initProductPricelist() {
 		orm.Many2one("company_id", "res.company", orm.FieldOpts{String: "Company"}),
 		orm.Integer("sequence", orm.FieldOpts{String: "Sequence", Default: 16}),
 		orm.One2many("item_ids", "product.pricelist.item", "pricelist_id", orm.FieldOpts{String: "Pricelist Rules"}),
+		orm.Many2one("country_group_id", "res.country.group", orm.FieldOpts{String: "Country Group"}),
 	)
 
+	// get_product_price: returns the price for a product in this pricelist.
+	// Mirrors: odoo/addons/product/models/product_pricelist.py Pricelist._get_product_price()
+	m.RegisterMethod("get_product_price", func(rs *orm.Recordset, args ...interface{}) (interface{}, error) {
+		if len(args) < 2 {
+			return float64(0), nil
+		}
+		env := rs.Env()
+		pricelistID := rs.IDs()[0]
+		productID, _ := args[0].(float64)
+		qty, _ := args[1].(float64)
+		if qty <= 0 {
+			qty = 1
+		}
+
+		// Find matching pricelist item
+		var price float64
+		err := env.Tx().QueryRow(env.Ctx(), `
+			SELECT CASE
+				WHEN pi.compute_price = 'fixed' THEN pi.fixed_price
+				WHEN pi.compute_price = 'percentage' THEN pt.list_price * (1 - pi.percent_price / 100)
+				ELSE pt.list_price
+			END
+			FROM product_pricelist_item pi
+			JOIN product_product pp ON pp.id = $2
+			JOIN product_template pt ON pt.id = pp.product_tmpl_id
+			WHERE pi.pricelist_id = $1
+			AND (pi.product_id = $2 OR pi.product_id IS NULL)
+			AND (pi.min_quantity <= $3 OR pi.min_quantity IS NULL)
+			ORDER BY pi.sequence, pi.id LIMIT 1`,
+			pricelistID, int64(productID), qty,
+		).Scan(&price)
+
+		if err != nil {
+			// Fallback to list price
+			env.Tx().QueryRow(env.Ctx(),
+				`SELECT pt.list_price FROM product_product pp JOIN product_template pt ON pt.id = pp.product_tmpl_id WHERE pp.id = $1`,
+				int64(productID)).Scan(&price)
+		}
+		return price, nil
+	})
+
 	// product.pricelist.item — Price rules
 	orm.NewModel("product.pricelist.item", orm.ModelOpts{
 		Description: "Pricelist Rule",
-		Order:       "applied_on, min_quantity desc, categ_id desc, id desc",
+		Order:       "sequence, id",
 	}).AddFields(
 		orm.Many2one("pricelist_id", "product.pricelist", orm.FieldOpts{
 			String: "Pricelist", Required: true, OnDelete: orm.OnDeleteCascade, Index: true,
 		}),
-		orm.Many2one("product_tmpl_id", "product.template", orm.FieldOpts{String: "Product"}),
+		orm.Many2one("product_id", "product.product", orm.FieldOpts{String: "Product Variant"}),
+		orm.Many2one("product_tmpl_id", "product.template", orm.FieldOpts{String: "Product Template"}),
 		orm.Many2one("categ_id", "product.category", orm.FieldOpts{String: "Product Category"}),
 		orm.Float("min_quantity", orm.FieldOpts{String: "Min. Quantity"}),
+		orm.Integer("sequence", orm.FieldOpts{String: "Sequence", Default: 5}),
 		orm.Selection("applied_on", []orm.SelectionItem{
 			{Value: "3_global", Label: "All Products"},
 			{Value: "2_product_category", Label: "Product Category"},