Struct ContextOverhead 

pub struct ContextOverhead {
    pub tool_count: usize,
    pub tool_schema_tokens: usize,
    pub instruction_tokens: usize,
    pub rules_block_tokens: usize,
}

A measured breakdown, in tokens, of the per-turn context lean-ctx adds.

Fields

tool_count: usize

Number of MCP tools exposed (the schema-bearing surface).

tool_schema_tokens: usize

Tokens for all exposed tool descriptions + input schemas.

instruction_tokens: usize

Tokens for the MCP server instructions block (capped at the instruction budget).

rules_block_tokens: usize

Tokens for the rules block injected into the host instruction file.

Implementations

impl ContextOverhead

pub fn total_tokens(&self) -> usize

Total per-turn overhead in tokens.

pub fn cached() -> Self

Process-cached overhead. The tool surface and rules block are static and the instruction block varies only with slow-moving session state, so a once-per-process measurement is the right tradeoff for callers that render repeatedly (the gain dashboard re-renders every second in --live) — it avoids per-tick disk I/O and re-tokenization.

pub fn measure() -> Self

Measure the overhead for the currently-configured MCP surface. Uses the same advertisement policy as the live tools/list handler (candidate set, profile gates, invoker, description compression), so the number reflects what this install actually advertises (#572).

pub fn measure_for_client(client_name: &str) -> Self

Self::measure with the instructions a named MCP client receives (clientInfo.name, e.g. claude-code): hook-covered clients and clients with an instruction cap get a different block.

impl ContextOverhead

pub fn measure_governor(arm: GovernorArm) -> Self

Per-turn prefix of the Claude Code governor setup (governor design v1, slice 1). Its hooks emit no session or per-prompt text, so the prefix is the rule block plus, in the MCP arm, one deferred-tool name line per tool: initialize instructions are suppressed (LEAN_CTX_RULES_INJECTION=off on the server) and schemas stay behind Tool Search until fetched (alwaysLoad: false). The name-line cost models Claude Code’s deferred-tool listing [inference, bench-verified].

Trait Implementations

impl Clone for ContextOverhead

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ContextOverhead

impl Debug for ContextOverhead

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

Formats the value using the given formatter.

impl Default for ContextOverhead

fn default() -> Self

Returns the “default value” for a type.

impl Eq for ContextOverhead

impl PartialEq for ContextOverhead

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ContextOverhead