Day 18 — horse health alerts and billing that actually flexes

This was the week I think I broke the most ground against the incumbents. Two systems went in that the existing barn software — based on every review I've read — fundamentally doesn't do well.

Horse health tracking with actual alerts. Vaccines tracked with due dates, with reminders firing 30 days out and again when overdue. Medications tracked with reorder thresholds, with a low-stock badge surfacing on the trainer dashboard. None of it is glamorous code, but the result is: a horse never silently goes overdue on a vaccine again, and you never run out of bute on a Tuesday morning. Competitors do "vaccine record entry" — they don't do alerts. That's the difference between a record-keeping tool and an operating system.

Flexible billing. This is the one I'm most happy about, because it's the wedge against incumbents at every tier. The schema went in: fee schedule items, billing packages, client-package assignments, billable charges, billing cycles. Then the surfaces:

• A fee schedule manager (full CRUD, category grouping, trainer-loggable flag)
• Configurable packages (replacing the hardcoded ProgramType enum I started with — bad early decision, fixed it)
• Per-client package assignment
• Variable charge entry — a trainer logs a hoof oil application or a haul-in fee mid-month, the manager reviews it, it goes on the invoice
• Bulk invoice generation — one click creates draft invoices for every active client
• A "trusted client" auto-send flag so reliable clients skip the review step
• An invoice correction flow (INV-1001 → INV-1001-R1 with line items pre-populated) because corrections are real life
• PDF generation via @react-pdf/renderer

And then QuickBooks Online integration on top of all of it — OAuth, AES-256-GCM encrypted token storage, automatic invoice push when a billing cycle generates. Not because every barn uses QBO, but because the ones that do absolutely will not switch software unless their accountant's books stay clean.

Two of the three things barn managers complained about most in every review I read: solved.