# Package scriptorium

Import path:

```go
import "gitea.maximumdirect.net/eric/scriptorium"
```

The root package is a public facade over Scriptorium's prompt execution use case. It keeps `internal/*` packages private while exposing typed construction, preparation, execution, inputs, results, and errors.

## Construct An Engine

```go
engine, err := scriptorium.NewEngine(scriptorium.Config{
	PromptDir:  "./examples/prompts",
	ProfileDir: "./examples/profiles",
	SchemaDir:  "./examples/schemas",
})
if err != nil {
	return err
}
```

`PromptDir` is required unless an explicit prompt source option is supplied. `ProfileDir` is optional; omit it to use built-in profiles only, or set it to overlay custom profiles above built-ins. `SchemaDir` defaults to the built-in schema directory. `Timeout` and `HTTPClient` configure the default OpenAI-compatible client used by `Run` when no custom LLM client is supplied.

## Asset Sources

Directory fields on `Config` remain the compatibility path. Explicit source options override the matching directory field:

- `WithPromptFS(fsys, root)` and `WithPromptFile(path)`
- `WithProfileFS(fsys, root)` and `WithProfileFile(path)`
- `WithSchemaFS(fsys, root)` and `WithSchemaFile(path)`

Prompt and profile sources load standard Scriptorium YAML with the same strict validation as directory sources. For `WithPromptFS`, the configured root is a containment boundary: prompt `content_file` paths resolve relative to the prompt file and must remain inside that root. Profile options overlay custom profiles above built-ins. For `WithSchemaFS`, prompt `schema_path` values resolve inside the configured root. Absolute paths and relative traversal outside those `fs.FS` roots are rejected. Schema file options expose the file by its base name.

## In-Memory Profiles

Use `WithProfiles` when the consuming application already has profile settings in typed Go configuration:

```go
profile := scriptorium.OpenAICompatibleProfile(scriptorium.OpenAICompatibleProfileConfig{
	ID:             "app.default",
	Endpoint:       "https://openrouter.ai/api/v1",
	Model:          "mistralai/mistral-small-3.2-24b-instruct",
	APIKeyRequired: true,
})

engine, err := scriptorium.NewEngine(cfg, scriptorium.WithProfiles(profile))
```

In-memory profiles have highest precedence, followed by configured profile file/FS/directory sources, then built-in profiles. Duplicate IDs in one `WithProfiles` call return `ErrInvalidConfig`.

`Profile` and `OpenAICompatibleProfileConfig` include endpoint, model, numeric defaults, service tier, reasoning effort, `APIKeyRequired`, and JSON-compatible `ExtraParams`. `WithProfiles` validates `ExtraParams` and returns `ErrInvalidConfig` for unsupported values such as functions, channels, non-string map keys, non-finite floats, or cyclic values. Raw API-key fields are not accepted. When `APIKeyRequired` is true, pass the secret with `RunRequest.APIKey`.

## Prepare A Prompt

`Prepare` resolves the prompt definition, profile, inputs, variables, output contract, structured-output metadata, and rendered messages without calling an LLM.

```go
prepared, err := engine.Prepare(ctx, scriptorium.RunRequest{
	PromptID: "generic.markdown_summary",
	Inputs: map[string]scriptorium.ArtifactRef{
		"transcript": scriptorium.File("./examples/fixtures/transcript.md"),
		"glossary":   scriptorium.File("./examples/fixtures/glossary.yml"),
	},
})
if err != nil {
	return err
}
_ = prepared.Messages
```

Input helpers:

- `scriptorium.File(path)` loads an input artifact from a file.
- `scriptorium.Inline(body)` passes inline input content.
- `scriptorium.InlineWithURI(uri, body)` passes inline content with URI metadata.

## Run A Prompt

`Run` prepares the prompt, calls the configured LLM client, builds the output artifact, and validates the output.

```go
result, err := engine.Run(ctx, scriptorium.RunRequest{
	PromptID: "generic.markdown_summary",
	APIKey:   apiKey,
	Inputs: map[string]scriptorium.ArtifactRef{
		"transcript": scriptorium.File("./examples/fixtures/transcript.md"),
		"glossary":   scriptorium.File("./examples/fixtures/glossary.yml"),
	},
})
if err != nil {
	return err
}
_ = result.Artifact
```

`RunResult` includes the run ID, output artifact, raw output, validation result, prompt/profile/model metadata, effective model parameters, input hashes, token/cache usage, and timing fields. Validation content failures return a successful `RunResult` with failed validation status. Runtime validation errors return `ErrValidation`.

For the public Go API, pass provider credentials with `RunRequest.APIKey`. The value is request-scoped, uses `json:"-"`, is preferred over profile `api_key_env` by the default OpenAI-compatible client, and is not included in `PreparedRun` or `RunResult` JSON. Normal Go string formatting of `RunRequest` reports only whether a direct key is set. Do not store raw keys in config, prompt files, or profile YAML.

Avoid logging raw request structs with reflection-based debug dumpers; exported fields remain visible to tools that bypass `String` and `GoString` methods.

## Inject An LLM Client

Use `WithLLMClient` for tests or custom model integrations:

```go
type fakeLLM struct{}

func (fakeLLM) Generate(ctx context.Context, req scriptorium.GenerateRequest) (*scriptorium.GenerateResponse, error) {
	return &scriptorium.GenerateResponse{
		Content: "generated text",
		Usage:   scriptorium.TokenUsage{TotalTokens: 12},
	}, nil
}

engine, err := scriptorium.NewEngine(cfg, scriptorium.WithLLMClient(fakeLLM{}))
```

The injected client receives the rendered prompt, effective execution target, target presence metadata for explicit numeric overrides, structured-output spec, and request API key when provided. `GenerateRequest.APIKey` also uses `json:"-"`, and normal Go string formatting reports only whether a direct key is set. Custom and fake clients should avoid logging or serializing it. `WithLLMClient(nil)` returns `ErrInvalidConfig`.

## Request Overrides

`RunRequest.Execution` accepts per-request overrides. Numeric override fields are pointers so explicit zero values are preserved:

```go
zero := 0
req.Execution = &scriptorium.ExecutionTargetOverride{
	MaxTokens: &zero,
}
```

`ExecutionTargetOverride.ExtraParams` accepts JSON-compatible values and copies typed maps/slices so later caller mutation does not affect the run. Unsupported values, non-string map keys, non-finite floats, and cycles return `ErrInvalidRequest`.

## Errors

Public methods wrap context while preserving stable sentinel checks with `errors.Is`:

- `ErrInvalidConfig`
- `ErrInvalidRequest`
- `ErrPromptNotFound`
- `ErrProfileNotFound`
- `ErrPromptLoad`
- `ErrProfileLoad`
- `ErrArtifactLoad`
- `ErrPromptRender`
- `ErrLLMGenerate`
- `ErrValidation`

Example:

```go
if errors.Is(err, scriptorium.ErrPromptNotFound) {
	return err
}
```

## Examples

Run the prepare-only example from the repository root:

```bash
go run ./examples/go-library/prepare
```