fix(provider): defaultModelIDs crashes /provider and /config/providers when a config-declared provider has zero models

Description

Provider.defaultModelIDs throws TypeError: Cannot read properties of undefined (reading 'id') for any provider whose models map is empty. Zero-model providers are a supported state in this repo (see provider.ts:1465 models: existing?.models ?? {} and the unconditional database[providerID] = parsed at :1554), but the live providers map can carry them and the crash fires on the next /provider or /config/providers HTTP request.

Where

• packages/opencode/src/provider/provider.ts:1112 — the offending function:

export function defaultModelIDs<T extends { models: Record<string, { id: string }> }>(providers: Record<string, T>) {
  return mapValues(providers, (item) => sort(Object.values(item.models))[0].id)
}

sort([]) returns [], so [0] is undefined and .id throws.

• packages/opencode/src/server/routes/instance/httpapi/handlers/provider.ts:59 — ProviderHttpApi.list (/provider) feeds Provider.defaultModelIDs(providers) from the live map.
• packages/opencode/src/server/routes/instance/httpapi/handlers/config.ts:28 — ConfigHttpApi.providers (/config/providers) does the same.

Both call sites feed from provider.list() (provider.ts:1707) which returns state.providers — the same database map that line 1554 keeps populating.

Steps to reproduce

opencode.jsonc with a bare custom provider (common LiteLLM / corporate gateway pattern):

{ "provider": { "my-gateway": { "name": "GW", "options": { "baseURL": "http://localhost:4000" } } } }

GET /config/providers or GET /provider → 500 TypeError from Provider.defaultModelIDs. The model picker gets no providers as a result.

Minimal JS reproduction (verified locally on the current dev tip):

import { mapValues, sortBy } from "remeda"
const defaultModelIDs = (p) => mapValues(p, (i) => sortBy(Object.values(i.models), (m) => m.id)[0].id)
defaultModelIDs({ litellm: { models: {} }, anthropic: { models: { sonnet: { id: "sonnet" } } } })
// → TypeError: undefined is not an object (evaluating '... [0].id')

How a zero-models provider can land in the live map

Two documented paths already produce zero-model providers — neither is filtered out before defaultModelIDs runs:

1. Bare config provider (this repro): models: existing?.models ?? {} (:1465) lands in the database unconditionally via :1554.
2. Plugin config() hook injecting a provider that is not in the models.dev catalog (see #25630 thread, 15 affected users; #44081 covers the related hook-ordering path, PR #38836 covers that separately).

Once the provider is in the database, every /provider and /config/providers request explodes.

Expected

defaultModelIDs should omit providers with no models from the default map, not throw. The consumer DefaultModelIDs schema is Record<string, string>; an absent key is semantically correct ("no default") for a provider with no models.

Suggested fix

Guard the lookup at the source so consumers see a clean Record<string, string>:

export function defaultModelIDs<T extends { models: Record<string, { id: string }> }>(providers: Record<string, T>) {
  return pickBy(
    mapValues(providers, (item) => sort(Object.values(item.models))[0]?.id),
    (id): id is string => typeof id === "string",
  )
}

pickBy is already imported from remeda in this file (:6).

A regression test would go next to the existing defaultModel* cases in packages/opencode/test/provider/provider.test.ts.

Related (NOT duplicates)

• #25630 / #44081 — plugin provider.models() hook ordering for config providers; #38836 covers it. Different code path; our fix complements, does not overlap.
• #35772 — different TypeError (reading 'provider', falsy plugin hook returns), fixed by #36102, assigned to Hona.
• #41360 — models.opencode.ai fetch failure drops config-declared models. Related symptom (empty models map), different root cause.