Struct ContextUsage 

pub struct ContextUsage {
    pub total_input_tokens: TokenCount,
    pub total_output_tokens: TokenCount,
    pub context_window_size: u32,
    pub current_input_tokens: TokenCount,
    pub current_output_tokens: TokenCount,
    pub cache_creation_tokens: TokenCount,
    pub cache_read_tokens: TokenCount,
}

Context window usage information.

Tracks token counts and calculates usage percentage based on current_usage from Claude Code’s status line. The current_usage object reflects the actual tokens being sent to the API in the current context window.

When current_usage is null (e.g., during /clear), all current_* fields are 0, which correctly shows 0% context usage.

Fields

total_input_tokens: TokenCount

Total input tokens across all turns (cumulative, for reference)

total_output_tokens: TokenCount

Total output tokens across all turns (cumulative, for reference)

context_window_size: u32

Maximum context window size for the model

current_input_tokens: TokenCount

Current context’s input tokens (from current_usage.input_tokens)

current_output_tokens: TokenCount

Current context’s output tokens (from current_usage.output_tokens)

cache_creation_tokens: TokenCount

Tokens written to cache (from current_usage.cache_creation_input_tokens)

cache_read_tokens: TokenCount

Tokens read from cache - this is the bulk of context (from current_usage.cache_read_input_tokens)

Implementations

impl ContextUsage

pub fn new(context_window_size: u32) -> Self

Creates a new ContextUsage with default values.

pub fn context_tokens(&self) -> TokenCount

Calculates the context tokens currently in use.

This is the actual context being sent to the API, calculated from:

• cache_read_tokens: Previously cached context being reused
• current_input_tokens: New input tokens in this turn
• cache_creation_tokens: New tokens being written to cache

When current_usage is null (e.g., after /clear), these are all 0.

pub fn total_tokens(&self) -> TokenCount

Calculates the total tokens used (cumulative, for reference).

pub fn usage_percentage(&self) -> f64

Returns the percentage of context window used (0.0 to 100.0).

Uses context_tokens() which reflects the actual tokens in the current context window (from current_usage). When current_usage is null, this returns 0%.

pub fn is_warning(&self) -> bool

Returns true if context usage is above the warning threshold (80%).

pub fn is_critical(&self) -> bool

Returns true if context usage is critical (>90%).

pub fn exceeds_200k(&self) -> bool

Returns true if exceeds 200K tokens (Claude Code’s extended context marker).

pub fn remaining_tokens(&self) -> TokenCount

Returns the remaining tokens before hitting context limit.

pub fn format(&self) -> String

Formats usage for display (e.g., “45.2% (26.4K/200K)”).

pub fn format_compact(&self) -> String

Formats usage compactly (e.g., “45%”).

Trait Implementations

impl Clone for ContextUsage

fn clone(&self) -> ContextUsage

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ContextUsage

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

Formats the value using the given formatter.

impl Default for ContextUsage

fn default() -> ContextUsage

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for ContextUsage

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for ContextUsage

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

Formats the value using the given formatter.

impl PartialEq for ContextUsage

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for ContextUsage

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

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl Copy for ContextUsage

impl StructuralPartialEq for ContextUsage