lean_ctx/core/value_gate/
cost_tracker.rs

1//! Deterministic execution-cost calculation in USD micros.
2
3const TOKENS_PER_MILLION: u128 = 1_000_000;
4
5/// Cost and token accounting for one model execution.
6#[derive(Debug, Clone, Default, PartialEq, Eq)]
7pub struct ExecutionCost {
8    pub input_tokens: u64,
9    pub output_tokens: u64,
10    pub cache_read_tokens: u64,
11    pub model: String,
12    pub provider: String,
13    pub estimated_cost_micros: u64,
14}
15
16/// Calculate cost using the model's published USD-per-million-token rates.
17pub fn calculate_cost(input: u64, output: u64, cache: u64, model: &str) -> u64 {
18    let (input_rate, output_rate) = match model {
19        "gpt-4o" => (2_500_000u128, 10_000_000u128),
20        "claude-sonnet" => (3_000_000u128, 15_000_000u128),
21        _ => (5_000_000u128, 15_000_000u128),
22    };
23    let total = input as u128 * input_rate
24        + output as u128 * output_rate
25        + cache as u128 * (input_rate / 10);
26    u64::try_from(total / TOKENS_PER_MILLION).unwrap_or(u64::MAX)
27}
28
29#[cfg(test)]
30mod tests {
31    use super::*;
32
33    #[test]
34    fn cost_calculation_gpt4o() {
35        assert_eq!(
36            calculate_cost(1_000_000, 1_000_000, 0, "gpt-4o"),
37            12_500_000
38        );
39    }
40
41    #[test]
42    fn cost_calculation_claude() {
43        assert_eq!(
44            calculate_cost(1_000_000, 1_000_000, 0, "claude-sonnet"),
45            18_000_000
46        );
47    }
48
49    #[test]
50    fn cost_calculation_unknown() {
51        assert_eq!(calculate_cost(1_000_000, 1_000_000, 0, "other"), 20_000_000);
52    }
53
54    #[test]
55    fn cache_uses_ten_percent_of_input_rate() {
56        assert_eq!(calculate_cost(0, 0, 1_000_000, "gpt-4o"), 250_000);
57    }
58}
lean_ctx/core/value_gate/cost_tracker.rs

lean_ctx/core/value_gate/
cost_tracker.rs
