Module usage 

Token usage tracking surfaces.

Four channels, finest granularity to coarsest:

• TraceSink: every provider call across every session in the runtime. Right for billing, audit, off-line analysis. Heavier than necessary if you only want totals. See crate::tracing.
• TurnEvent::Usage / TurnEvent::ChildUsage: live during a turn, one event per LLM iteration. Usage is the parent’s own model call; ChildUsage carries session_id + source so a UI can group child traffic (e.g. by subagent). Right for live counters.
• TurnResult::usage / TurnResult::children_usage: per-turn snapshot at completion. usage is parent-only; children_usage is a per-(source, model) breakdown. TurnResult::total_usage sums both. Right for “what did this message cost.”
• SessionUsageReport (session.usage_report()): aggregate across the whole session, broken down by source × model. Right for dashboards and “session so far.”

Modules

sources

Well-known source labels used by the runtime and first-party plugins.

Structs

SessionUsageReport

TokenLedgerEntry

A single row in the token cost ledger. One per unique (source, model) pair — accumulated, not per-call.

TokenUsage

Token usage statistics from an LLM call.

UsageReportRow

UsageTotals

Functions

diff_token_ledger

diff_usage_reports