Model IDs are pass-through

The rule#

A library that maintains a hardcoded list of valid model IDs will, inevitably, reject a model that its user is entitled to use — because the model shipped last Tuesday and the library has not cut a release.

A model released after your skyl build works immediately.

The evidence#

Consider a four-week window in mid-2026:

Any hardcoded table is wrong within weeks. And the failure mode is the worst possible one: skyl rejecting a model you are already paying for.

What it costs you#

What follows from it#

• Client.Models(ctx) asks the provider live rather than returning a compiled-in list, so the answer is never stale.
• The sandbox serves a deliberately small model catalogue and 404s anything else — a sandbox that accepted every string would never exercise the not-found path, which is the only thing between a typo and an unactionable failure.
• Model metadata, when it lands, will be a generated registry refreshed from live endpoints by CI — never a hand-typed table that silently rots.

In practice#

type Config struct {
	FastModel  string `env:"FAST_MODEL,required"`
	SmartModel string `env:"SMART_MODEL,required"`
}

type Config struct {
	FastModel  string `env:"FAST_MODEL,required"`
	SmartModel string `env:"SMART_MODEL,required"`
}

// A cheap sanity check. Per request it doubles your calls, and the list is a
// snapshot that can go stale between the check and the call.
if err := checkModels(ctx, client, cfg.FastModel, cfg.SmartModel); err != nil {
	return err
}

// A cheap sanity check. Per request it doubles your calls, and the list is a
// snapshot that can go stale between the check and the call.
if err := checkModels(ctx, client, cfg.FastModel, cfg.SmartModel); err != nil {
	return err
}

Recorded as ADR-0004.