1 min lesson
The over-scoping trap
Put this idea into your own words: "The most common build-round failure is starting an ambitious end-to-end architecture and demoing nothing."
Step 1 of 2
“I scoped to one metered event type through rating to a draft invoice so I could demo the full path. The rating step is idempotent and keyed on a usage-event id, so a replay can't double-bill. I left the GL posting behind an interface - the subledger emits journal entries and wiring those to the ERP is the next step. An agent could draft the daily usage-to-billing reconciliation, but I'd gate it: it proposes adjustments, a human posts them.”
The most common build-round failure is starting an ambitious end-to-end architecture and demoing nothing. A working usage-to-invoice slice with two honest trade-offs beats an elaborate revenue-subledger design with no running code. If you're behind at the halfway mark, cut a feature, never the demo.
Treat the finance system as a product with internal customers, out loud. Ask “who consumes this output - does the controller close on it or does Sales quote off it?” early and let the answer drive your data model and grain. That product framing is exactly what the build round is built to detect and it's the difference between a configurator and an architect.