Separate a business policy from its implementation
Labels such as A-Book, B-Book and hybrid do not describe a complete technology specification. Record what happens for each relevant account, instrument and order condition: which system makes a routing decision, who can change it and where the decision is logged.
A technology review does not select a risk model or establish the permissions required to operate it. Those responsibilities remain with the brokerage and its advisers. The implementation brief translates approved workflows into observable system behaviour.
Compare the evidence each workflow needs
| Area | External-routing workflow | Internal-dealing workflow |
|---|---|---|
| Order lifecycle | Trace acknowledgements, fills and rejections across counterparties | Trace accepted instructions and internal state changes |
| Pricing | Check the pricing source and execution-side dependencies separately | Check the approved pricing rules and their change history |
| Operator controls | Define counterparty interruption and reconciliation procedures | Define permissions, intervention records and escalation |
| Mixed workflow | Record routing selection and fallback conditions | Reconcile internal and external records without losing the decision trail |
The table identifies review topics rather than asserting that every platform or provider exposes the same controls. Verify each required function in the proposed environment.
Use scenario testing rather than a label
Illustrative test: two approved account groups follow different execution paths. A reviewer submits representative test instructions and checks whether the resulting records show the intended path and consistent final states. The test also covers a denied configuration change and an unavailable dependency.
The useful output is a responsibility matrix, sample event traces and a list of unresolved limitations. A sales description saying “hybrid supported” is insufficient without that evidence. If existing workflows must be preserved, collect the current configuration and the rights available to inspect or modify it before planning a transition.