Enum Command 

pub enum Command {
    Infer {
        prompt: String,
        max_tokens: u32,
        images: Vec<u32>,
    },
    Open {
        path: String,
    },
    Slice {
        handle: u32,
        offset: u64,
        len: u64,
    },
    SliceBytes {
        handle: u32,
        offset: u64,
        len: u64,
    },
    PageText {
        handle: u32,
        page: u32,
    },
    PageImage {
        handle: u32,
        page: u32,
    },
    DocumentText {
        handle: u32,
    },
    ImageOp {
        handle: u32,
        op: ImageOperation,
    },
    Emit {
        progress: Value,
    },
    Done {
        result: Value,
    },
    Fail {
        code: String,
        message: String,
    },
}

What a guest asks the host to do, returned from its init/step exports.

Variants

Infer

Run a prompt against the job’s model.

Fields

prompt: String

The prompt to generate from.

max_tokens: u32

Upper bound on tokens generated. A guest can also end generation early by returning TokenAction::Stop from its on_token export.

images: Vec<u32>

Images to accompany the prompt, named by handle.

Handles rather than bytes, for the same reason file contents are not handed over: an image can be tens of megabytes, and routing it through guest memory would put the 4 GiB wasm32 ceiling back in play for no benefit. The host already holds the bytes; it can pass them to the model directly.

Requires a model with vision capability. Empty for ordinary text-only inference, which is why it is #[serde(default)] — a block compiled before this field existed still deserializes.

Open

Open a file. Capability-checked against the job’s spec.

Yields a handle and a length rather than contents — see the crate docs on why bulk data does not cross this boundary.

Fields

path: String

Path to open. Denied unless the spec grants read access to it.

Slice

Pull one bounded window of an open file into guest memory.

The guest picks len, so the guest sets its own memory ceiling.

Fields

handle: u32

Handle from a previous Command::Open.

offset: u64

Byte offset to read from. u64 so that files far larger than a guest could hold remain fully addressable.

len: u64

Maximum bytes to return. The host may return fewer; see Event::Sliced.

SliceBytes

Pull one bounded window of an open file as raw bytes.

The binary counterpart to Command::Slice. Prefer Slice for text: it needs no encoding, and it handles the character-boundary problem for you. This exists for blocks that genuinely need bytes — inspecting an image header, say — and pays base64’s cost to carry them.

Fields

handle: u32

Handle from a previous Command::Open.

offset: u64

Byte offset to read from.

len: u64

Maximum bytes to return.

PageText

Extract one page of a document as text.

Fails when the document has no text layer; check MediaKind::Document::has_text_layer first.

Fields

handle: u32

Handle from a previous Command::Open.

page: u32

Zero-based page number.

PageImage

Render one page of a document to an image.

Yields a new handle referring to the rendered image, which can then be named in Command::Infer. That indirection is deliberate: the image stays host-side like every other bulk value, and a rendered page is usable exactly wherever a file-backed image is.

Fields

handle: u32

Handle from a previous Command::Open.

page: u32

Zero-based page number.

DocumentText

Every character of text in a document, in one call.

What most callers reading a PDF actually want, and the direct way to ask for it. Before this existed the only route was Command::PageText with page: 0, which reads like “the first page” and quietly means “everything” whenever the extractor emitted no page breaks — a gap that cost a real user two iterations and nearly a wrong conclusion about whether cuttlefish could read their corpus at all.

Prefer this over walking pages unless the pages are genuinely needed separately: the whole document is one extraction either way.

Fields

handle: u32

Handle from a previous Command::Open.

ImageOp

Transform an image handle, yielding a new image handle.

Same indirection as Command::PageImage, and for the same reason: pixels stay host-side, and the result is usable exactly wherever a file-backed image is — including as an Command::Infer image.

This is the one image operation that needs a decoder, which is why it lives here rather than in the guest. Metadata (dimensions, EXIF, chunk structure) is header parsing and is available to any script without a host round trip or a feature flag; looking at the pixels is not.

Hosts built without the image-ops feature reject this with a clear message rather than pretending to succeed.

Fields

handle: u32

Handle from a previous Command::Open or Command::PageImage.

op: ImageOperation

What to do to it.

Emit

Report progress to whoever is watching the job’s event stream.

Fields

progress: Value

Arbitrary JSON, forwarded verbatim to the job’s subscribers.

Done

Finish successfully with this payload.

Fields

result: Value

The job’s result, shaped by the spec’s declared output.

Fail

Give up. The job ends with this code and message, and no result.

Fields

code: String

Machine-readable code; see error_codes.

message: String

Human-readable explanation.

Trait Implementations

impl Clone for Command

fn clone(&self) -> Command

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Command

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Command

fn deserialize<__D>( __deserializer: __D, ) -> Result<Command, <__D as Deserializer<'de>>::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Command

fn eq(&self, other: &Command) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Command

fn serialize<__S>( &self, __serializer: __S, ) -> Result<<__S as Serializer>::Ok, <__S as Serializer>::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Command