Struct Prompt 

#[non_exhaustive]
pub struct Prompt {
    pub tier: ModelTier,
    pub system: Option<String>,
    pub messages: Vec<Turn>,
    pub json_schema: Option<Value>,
    pub max_tokens: u32,
    pub tools: Vec<ToolSpec>,
    pub tool_choice: Option<ToolChoice>,
}

One completion request: the tier asked for, the conversation so far, and what the caller will accept back.

#[non_exhaustive]: build one with Prompt::new and the builder methods rather than a struct literal. What a v2 port has to carry — tools, temperature, a stop sequence — should not be a breaking change for every caller, the same way Message is built.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

tier: ModelTier

system: Option<String>

messages: Vec<Turn>

json_schema: Option<Value>

A JSON Schema (draft 2020-12) the answer should conform to. When set, the adapter asks its provider for structured output; a provider that honours it fills Completion::json, and one that cannot leaves the raw answer in Completion::text with json None, rather than failing the call.

max_tokens: u32

tools: Vec<ToolSpec>

The tools the model may call. Empty by default: a prompt that sends no tools behaves exactly as it did before tools existed, and an adapter is never asked to carry tools it was not given.

tool_choice: Option<ToolChoice>

How the model should choose among Prompt::tools. None leaves the choice to the provider’s own default; the builder sets it.

Implementations

impl Prompt

pub fn new(tier: ModelTier) -> Self

An empty prompt for tier: no system prompt, no messages, no schema, no tools, and DEFAULT_MAX_TOKENS as the ceiling. Everything else is a builder method.

pub fn tool(self, tool: ToolSpec) -> Self

Offers the model one more tool it may call.

pub fn tools(self, tools: impl IntoIterator<Item = ToolSpec>) -> Self

Offers the model every tool in tools.

pub fn tool_choice(self, tool_choice: ToolChoice) -> Self

Steers how the model chooses among the offered tools.

pub fn system(self, system: impl Into<String>) -> Self

The standing instruction the model answers under.

pub fn user(self, content: impl Into<String>) -> Self

Appends a Turn::user — the common case, a one-message prompt.

pub fn user_parts(self, parts: impl IntoIterator<Item = Part>) -> Self

Appends a Turn::user_parts — a user message carrying text and images in order (issue #628).

pub fn assistant(self, content: impl Into<String>) -> Self

Appends a Turn::assistant.

pub fn turn(self, turn: Turn) -> Self

Appends a whole turn, for a conversation built elsewhere.

pub fn json_schema(self, schema: Value) -> Self

Asks for structured output conforming to schema; a successful completion then carries the parsed value in Completion::json.

pub fn max_tokens(self, max_tokens: u32) -> Self

The token ceiling for the answer.

pub fn has_images(&self) -> bool

Whether any turn carries an image Part (issue #628). The router and the tool loop gate Capability::Images on this, exactly as they gate Capability::Tools on Prompt::tools.

pub fn check_images(&self) -> Result<(), TextModelError>

Refuses a prompt whose images exceed a bound (issue #628), without encoding anything: the count against MAX_PROMPT_IMAGES, each image’s encoded_image_len against MAX_IMAGE_ENCODED_BYTES, and their sum against MAX_PROMPT_IMAGE_ENCODED_BYTES.

Errors

TextModelError::ImageLimit, naming which bound was crossed: ImageLimit::TooMany, ImageLimit::ImageTooLarge (with the 0-based index among the prompt’s images) or ImageLimit::TotalTooLarge.

Trait Implementations

impl Clone for Prompt

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Prompt

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

Formats the value using the given formatter.

impl PartialEq for Prompt

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Prompt