Odoo merchants control shipping margin one carrier at a time, and it rarely holds up. The stock delivery app gives you delivery.carrier with a "Based on Rules" pricing type, but its rules are flat variable/operator/value rows scoped to one carrier — there is no cross-carrier markup layer, no free-shipping threshold that varies by region, no handling fee that stacks on top of the raw carrier quote, and no way to apply a margin percentage to what a real-time carrier connector (base_delivery_carrier_label, DHL, UPS, FedEx) returns at checkout. Merchants end up editing dozens of carrier records by hand, hard-coding shipping products, or eating negative margin on heavy or remote-zone orders. Native runs out of road exactly where shipping stops being a fixed price and starts being a policy.

This module adds a dedicated rule engine that evaluates on top of your existing carriers instead of replacing them. We introduce a shipping.rate.rule model (models.Model) with fields for weight bands, order value bands, destination zone (linked to res.country / res.country.group / state), carrier scope, and a priority sequence so overlapping rules resolve deterministically. A compute method decorated with @api.depends recalculates the shipping price whenever the cart total, weight, or delivery address changes, and we override the carrier's rate_shipment() / _get_price_available() so the engine feeds Odoo's standard checkout, sale order, and delivery flow — the customer sees one final number, correctly, in both the eCommerce checkout and back-office Sales quotations. Per-carrier markup is applied as either a fixed amount or a margin percentage against the live carrier cost, so real-time rates from a connector still carry your margin.

Free-shipping thresholds are first-class: define "free over X in zone Y for carrier Z", with optional promo windows driven by Odoo ir.cron automated actions, and the engine writes the discount as a proper delivery line so tax and reporting stay clean. Handling fees and surcharges (fuel, oversize, remote-area) are their own rule type that stacks after the base rate. Everything is exposed through backend views (XML list/form with an OWL-driven rule tester where useful), guarded by ir.model.access.csv plus record rules for multi-company setups, and every rate decision is auditable. Because it hooks the standard carrier interface, the same rules are honored by the website checkout, the sale.order back office, and any integration calling in over XML-RPC or JSON-RPC.

This is a build-to-order engagement, not an instant download. We start with a short scoping call to map your carriers, zones, and margin policy, then build the module against your target version — Odoo 17.0, 18.0, or 19.0, Community or Enterprise (we flag any Enterprise-only carrier connector dependencies up front). Typical delivery is 2 to 4 weeks from confirmed scope. You get the installable source, UAT on a staging database, a rollback plan, and a post-go-live support window — and you own the git repository at handover.