Files
promptkit/backends.go

100 lines
4.3 KiB
Go

package promptkit
import (
"gitea.maximumdirect.net/eric/promptkit/internal/backend"
"gitea.maximumdirect.net/eric/promptkit/internal/domain"
)
// BackendOpenRouter is the reserved ID of Promptkit's built-in OpenRouter
// backend.
const BackendOpenRouter = backend.OpenRouterID
// BackendLocal is the case-sensitive conventional ID used by [LocalBackend].
// It is not a built-in or reserved backend and must be registered with
// [WithBackend].
const BackendLocal = "local"
// Backend configures one engine-scoped OpenAI-compatible backend.
//
// Backend has no stable JSON representation. Use keyed literals so additions
// to this configuration value do not break source compatibility.
type Backend struct {
// ID is the stable, case-sensitive registry key. NewEngine trims it and
// requires a non-blank value. BackendOpenRouter is reserved.
ID string
// Endpoint is the OpenAI-compatible base endpoint. NewEngine trims it and
// requires an absolute HTTP or HTTPS URL with a host and without user
// information, a query string, or a fragment. Paths are allowed.
Endpoint string
// APIKeyEnv optionally names the environment variable containing the API
// key. NewEngine trims it and requires the portable form
// [A-Za-z_][A-Za-z0-9_]*. Store only the name, never a credential value.
APIKeyEnv string
// ExtraParams contains backend-wide request defaults. Values must be
// JSON-compatible, finite, acyclic, and keyed by non-empty strings. Keys
// must not be model, session_id, messages, temperature, max_tokens, top_p,
// service_tier, reasoning_effort, or response_format. An empty map supplies
// no defaults. NewEngine deeply copies the map.
ExtraParams map[string]any
// ConcurrencyLimit is the maximum number of simultaneous model-generation
// calls allowed for this backend within one Engine. Zero leaves the backend
// unlimited. A negative value makes NewEngine fail with ErrInvalidConfig.
ConcurrencyLimit int
// QueueCapacity controls how many additional Run calls may be admitted
// beyond ConcurrencyLimit. Nil uses 1024 when ConcurrencyLimit is positive;
// a pointer uses its exact value, including zero. The pointed-to value must
// be non-negative, and QueueCapacity must be nil when ConcurrencyLimit is
// zero. Their sum must fit in an int. WithBackend copies the value and does
// not retain the pointer.
QueueCapacity *int
}
// LocalBackend returns a caller-owned Backend for a conventional local
// OpenAI-compatible endpoint. It sets ID to BackendLocal and copies endpoint
// and concurrencyLimit into Endpoint and ConcurrencyLimit without
// normalization or validation. APIKeyEnv, ExtraParams, and QueueCapacity keep
// their zero values.
//
// LocalBackend does not read environment variables, register the value, or
// mutate engine or package state. Supply the returned value through
// [WithBackend]; [NewEngine] then applies the ordinary backend validation and
// concurrency semantics, including default queue capacity for a positive
// limit, unlimited behavior for zero, and ErrInvalidConfig for a negative
// limit.
func LocalBackend(endpoint string, concurrencyLimit int) Backend {
return Backend{
ID: BackendLocal,
Endpoint: endpoint,
ConcurrencyLimit: concurrencyLimit,
}
}
// WithBackend adds one Backend registration to the constructed Engine.
//
// Registrations accumulate in option order. Every normalized ID must be unique
// across consumer registrations and built-ins; a duplicate or invalid
// definition makes NewEngine fail with ErrInvalidConfig. In particular,
// BackendOpenRouter cannot be replaced. The immutable registration is scoped
// to the resulting Engine and cannot be enumerated, replaced, removed, or
// mutated after construction. WithBackend does not install package-global
// state.
func WithBackend(backend Backend) Option {
queueCapacity := 0
queueCapacitySet := backend.QueueCapacity != nil
if queueCapacitySet {
queueCapacity = *backend.QueueCapacity
}
return optionFunc(func(options *engineOptions) error {
options.backends = append(options.backends, domain.Backend{
ID: backend.ID,
Endpoint: backend.Endpoint,
APIKeyEnv: backend.APIKeyEnv,
ExtraParams: backend.ExtraParams,
ConcurrencyLimit: backend.ConcurrencyLimit,
QueueCapacity: queueCapacity,
QueueCapacitySet: queueCapacitySet,
})
return nil
})
}