Client¶

The Client type is the high-level entry point to the LiteRT-LM runtime. Always pair New with defer client.Close() to release the underlying engine handles.

client, err := litertlm.New(ctx,
    litertlm.WithLib("/abs/path/to/dist/lib"),
    litertlm.WithModel("/abs/path/to/model.litertlm"),
    litertlm.WithBackend("cpu"),
    litertlm.WithMaxTokens(4096),
)
defer client.Close()

Creating `New(ctx, opts...)` clients¶

litertlm.New aggregates the C-API Engine and EngineSettings into a single Client value. The Client owns both; Close releases them in the correct order.

Construction options¶

Use functional options to specify environment and inference engine settings.

Library and model¶

Option	Effect
`WithLib(dir)`	Directory holding `liblitertlm_c_cpu.*` etc. Empty → `$LITERTLM_LIB`.
`WithModel(path)`	Path to a `.litertlm` file. Empty → `$LITERTLM_MODEL`.
`WithBackend(b)`	`"cpu"` (default) or `"gpu"`.
`WithVisionBackend(b)`	Optional extra backend for vision inputs.
`WithAudioBackend(b)`	Optional extra backend for audio inputs.

Engine settings¶

Option	Effect
`WithMaxTokens(n)`	Total token budget (prompt + output). Default 4096.
`WithCacheDir(dir)`	Engine artefact cache. Propagated to vision and audio executors.
`WithActivationDataType(t)`	0=F32, 1=F16, 2=I16, 3=I8.
`WithPrefillChunkSize(n)`	CPU-backend prefill chunk size for dynamic models.
`WithSpeculativeDecodingEnabled(on)`	Toggle multi-token-prediction speculative decoding (Gemma 4 supported). See `examples/speculative/` for a side-by-side throughput comparison.
`WithBenchmarkEnabled()`	Turn on benchmark collection. Read per-call metrics via `Response.Benchmark()`.
`WithParallelSectionLoading(on)`	Parallel deserialization of `.litertlm` container sections. Defaults to true.
`WithDispatchLibDir(dir)`	LiteRT dispatch library directory for the NPU backend.

Logging¶

Option	Effect
`SetMinLogLevel(lvl)`	Package-level function (not a Client option). `LogVerbose` / `LogDebug` / `LogInfo` / `LogWarning` / `LogError` / `LogFatal` / `LogQuiet`. Call before `New` to override the C-side default of `LogInfo`.

Sampler defaults¶

Option	Effect
`WithDefaultSampler(p)`	Sampler used for every `Generate` unless overridden per-call by `WithSampler`.

Client methods¶

`Generate(ctx, prompt, opts...)`¶

Synchronous one-shot inference. Returns the first candidate's text.

Per-call options are RuntimeOption values, shared with GenerateData and Chat.Send*:

Option	Effect
`WithMaxOutputTokens(n)`	Cap output tokens for this call.
`WithSampler(p)`	Override the Client's default sampler.

text, err := client.Generate(ctx, "The capital of France is")

ctx cancellation is propagated to Session.Cancel internally, so context.WithTimeout and context.WithCancel apply:

ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
defer cancel()

text, err := client.Generate(ctx, prompt)
if errors.Is(err, context.DeadlineExceeded) {
    // Model didn't finish in time.
}

`GenerateStream(ctx, prompt, opts...)`¶

Provides access to token-by-token streaming.

for chunk, err := range client.GenerateStream(ctx, prompt) {
    if err != nil {
        return err
    }
    fmt.Print(chunk.Text)
    if chunk.Final {
        fmt.Println()
    }
}

Chunk is a value type:

type Chunk struct {
    Text  string
    Final bool
}

`GenerateResponse(ctx, prompt, opts...)`¶

GenerateResponse returns a rich-output via *Response that exposes per-candidate text plus score and token-length accessors:

resp, err := client.GenerateResponse(ctx, prompt)
if err != nil { return err }

fmt.Println(resp.Text())                    // first candidate
fmt.Println(resp.NumCandidates())           // usually 1 with default sampler
score, ok := resp.Score(0)                  // (placeholder, always ok=true for non-scoring sources)
length, ok := resp.TokenLength(0)           // (false unless ScoreTexts populated it)

Multimodal inputs¶

When the model supports vision or audio (and WithVisionBackend / WithAudioBackend are set), use the *Multi methods. They take a []litertlm.Part instead of a string prompt; everything else (opts, streaming, cancellation, response shape) is identical.

Method	Returns
`GenerateMulti`	`(string, error)`
`GenerateMultiStream`	`iter.Seq2[Chunk, error]`
`GenerateMultiResponse`	`(*Response, error)`

These are one-shot: each call opens a fresh Conversation, runs one inference, and discards it. KV state does not persist between calls. For successive multimodal turns that share conversation state, use Chat.SendMulti / Chat.SendMultiStream (see Chat).

Building Parts¶

Constructor	Purpose
`Text(s)`	Text prompt segment.
`Image(b)`	Image bytes (no MIME claimed).
`ImageWithMime(b, "image/jpeg")`	Explicit MIME (jpeg / png / webp / gif / bmp).
`ImageFromFile(path)`	Read file; MIME from extension.
`Audio(b)` / `AudioWithMime(b, mime)` / `AudioFromFile(path)`	Audio analogues.

Example — vision Q&A¶

img, err := litertlm.ImageFromFile("/path/to/photo.jpg")
if err != nil { return err }

text, err := client.GenerateMulti(ctx, []litertlm.Part{
    img,
    litertlm.Text("What objects are visible?"),
})