Struct ModelContext 

pub struct ModelContext<'a> {

    pub author: &'a MessageAuthor,
    pub model: &'a ModelRouter,
    pub provider: &'a str,
    pub context_provider: &'a str,
    pub session_id: &'a str,
    pub cancellation: Option<&'a ModelCancellation>,
    pub session_context: &'a SessionContext,
    pub metadata: &'a BTreeMap<String, Value>,
    pub turn_id: &'a str,
    pub model_step: usize,
    pub context_window: i64,
    pub token_estimate: TokenEstimate,
    pub instructions: &'a str,
    pub last_usage: Option<&'a TokenUsage>,
    pub tools: &'a Catalog,
    pub events: &'a mut Vec<EventMsg>,
    pub usage: &'a mut Vec<(String, TokenUsage)>,
    /* private fields */
}

Mutable state exposed immediately before a model request.

Fields

author: &'a MessageAuthor

Trusted provenance of the message that initiated the active turn.

model: &'a ModelRouter

The model.

provider: &'a str

The provider.

context_provider: &'a str

The route whose accepted output last contributed to durable context.

session_id: &'a str

The session identifier.

cancellation: Option<&'a ModelCancellation>

Cause recorded before model preparation is cancelled.

session_context: &'a SessionContext

The session context.

metadata: &'a BTreeMap<String, Value>

The metadata.

turn_id: &'a str

The turn identifier.

model_step: usize

The model step.

context_window: i64

The context window.

token_estimate: TokenEstimate

Shared byte-based estimate used by context policies.

instructions: &'a str

The instructions.

last_usage: Option<&'a TokenUsage>

The last usage.

tools: &'a Catalog

The tools.

events: &'a mut Vec<EventMsg>

The events.

usage: &'a mut Vec<(String, TokenUsage)>

Completed preparation calls, with their actual routes and usage.

Implementations

impl ModelContext<'_>

pub fn record_usage(&mut self, route: &str, usage: TokenUsage)

Accounts for a preparation call on its actual model route.

pub fn disable_hosted_tools(&mut self)

Prevents provider-hosted tools for this model step.

pub fn input(&self) -> ModelInput<'_>

Returns durable provider-neutral model context.

pub fn rewrite_input( &mut self, reason: ContextRewriteReason, input: impl IntoIterator<Item = impl Into<Arc<Value>>>, ) -> Result<()>

Replaces active model context and advances its rewrite epoch once per boundary.

Errors

Returns an error if validation or an operation required by this function fails.

pub fn append_model_input(&mut self, item: Value)

Appends durable provider context without adding synthetic replay history.

pub fn push_input(&mut self, item: Value) -> Result<MessageTarget>

Appends durable input to model context and its transcript journal.

Errors

Returns an error if validation or an operation required by this function fails.

pub fn estimated_input_tokens(&self) -> i64

Estimates visible history, instructions, and tool schemas using the session policy.