Design docs

A design doc is the plan for a feature, written before it was built. Each one here has shipped. Each page opens with three lines: what was decided, the release and pull request (PR) that shipped it, and the doc that describes how it works now. The code changed after some of them, so read that current doc first.

Come here for the reasoning behind a feature. The user docs start at Hardcount docs.

Design	What was decided	Shipped	Current docs
Billing thresholds	Invoice a subscription early when its spend or usage reaches a cap you set.	v0.1.0, #29	Feature list; ADR-065, ADR-066
CC on billing emails	Copy up to 10 more addresses on invoice, receipt, payment and credit-note emails.	v0.2.0, #393	No guide yet: ADR-082, API reference
Create-preview endpoint	Show a customer’s next invoice before it is made.	v0.1.0, #28	Feature list; no ADR, the code is the record
Customer usage endpoint	One call returns what a customer used and what it costs.	v0.1.0, #26	The Hardcount API; no ADR, the code is the record
Multi-dimensional meters	One meter prices each model and token type at its own rate.	v0.1.0, #20	AI pricing; ADR-044, ADR-045, ADR-070
Pricing recipes	Ready-made pricing set up in one call.	v0.1.0, #23	AI pricing; ADR-085
Provider cost tables	Record what each AI provider charges you, to show your margin.	v0.1.0, #373	AI pricing; ADR-079
Prepaid commits	Credit a customer pays for up front, then uses up.	v0.1.0, #371	AI pricing; ADR-078
Paid-commit credit-note relief	Refund the unused part of a paid prepaid commit, at the purchase rate.	v0.2.0, #391	No guide yet: ADR-080, API reference

The decision records (ADRs) are in docs/adr/. Failure modes found while benchmarking are in the failure-mode catalog.