use crate::common::{
ReceiptId, TaskId, ValidationError, deserialize_milliunit, deserialize_schema_version,
validate_milliunit, validate_schema_version,
};
use crate::execution::{ContextBalanceV1, ExecutionReceiptV1};
use crate::{EvidenceRefV1, MoneyV1, UsageBreakdownV1};
use serde::{Deserialize, Serialize};
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct SavingsObservationV1 {
pub observation_id: String,
pub provider_id: String,
pub model_id: String,
pub original_usage: UsageBreakdownV1,
pub actual_usage: UsageBreakdownV1,
pub local_cost_estimate: MoneyV1,
pub evidence_refs: Vec<EvidenceRefV1>,
pub observed_at: String,
pub runtime_version: String,
pub sequence_number: u64,
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "snake_case")]
pub enum MeasurementMethod {
ProviderReported,
Estimated,
Unavailable,
}
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(deny_unknown_fields)]
pub struct SavingsReceiptV1 {
#[serde(deserialize_with = "deserialize_schema_version")]
pub schema_version: u32,
pub savings_id: String,
pub task_id: TaskId,
pub baseline_receipt_id: ReceiptId,
pub treatment_receipt_id: ReceiptId,
pub baseline_cost_micros: u64,
pub treatment_cost_micros: u64,
pub avoided_cost_micros: u64,
pub baseline_tokens: ContextBalanceV1,
pub treatment_tokens: ContextBalanceV1,
#[serde(deserialize_with = "deserialize_milliunit")]
pub token_savings_ratio_milli: u16,
pub quality_preserved: bool,
#[serde(deserialize_with = "deserialize_milliunit")]
pub quality_baseline_score_milli: u16,
#[serde(deserialize_with = "deserialize_milliunit")]
pub quality_treatment_score_milli: u16,
pub measurement_method: MeasurementMethod,
pub context_strategy: String,
pub methodology_version: String,
pub evidence_refs: Vec<EvidenceRefV1>,
pub decision_refs: Vec<String>,
pub signature: String,
}
impl SavingsReceiptV1 {
pub fn validate(&self) -> Result<(), ValidationError> {
validate_schema_version(self.schema_version)?;
self.baseline_tokens.validate()?;
self.treatment_tokens.validate()?;
validate_milliunit(self.token_savings_ratio_milli, "token_savings_ratio_milli")?;
validate_milliunit(
self.quality_baseline_score_milli,
"quality_baseline_score_milli",
)?;
validate_milliunit(
self.quality_treatment_score_milli,
"quality_treatment_score_milli",
)?;
if self.avoided_cost_micros > self.baseline_cost_micros {
return Err(ValidationError::new(
"avoided_cost_micros exceeds baseline_cost_micros",
));
}
if self.quality_preserved
!= (self.quality_treatment_score_milli >= self.quality_baseline_score_milli)
{
return Err(ValidationError::new(
"quality_preserved does not match quality scores",
));
}
Ok(())
}
pub fn compute_from_arms(
baseline: &ExecutionReceiptV1,
treatment: &ExecutionReceiptV1,
) -> Self {
let baseline_cost_micros = baseline.actual_cost_micros;
let treatment_cost_micros = treatment.actual_cost_micros;
let baseline_provider_tokens = baseline.context_balance.provider_billed_tokens;
let treatment_provider_tokens = treatment.context_balance.provider_billed_tokens;
let savings_id = format!(
"savings-{}-{}",
baseline.receipt_id.as_str(),
treatment.receipt_id.as_str()
);
let mut evidence_refs = baseline.evidence_refs.clone();
evidence_refs.extend(treatment.evidence_refs.iter().cloned());
let mut decision_refs = baseline.decision_refs.clone();
decision_refs.extend(treatment.decision_refs.iter().cloned());
Self {
schema_version: baseline.schema_version,
savings_id,
task_id: baseline.task_id.clone(),
baseline_receipt_id: baseline.receipt_id.clone(),
treatment_receipt_id: treatment.receipt_id.clone(),
baseline_cost_micros,
treatment_cost_micros,
avoided_cost_micros: baseline_cost_micros.saturating_sub(treatment_cost_micros),
baseline_tokens: baseline.context_balance.clone(),
treatment_tokens: treatment.context_balance.clone(),
token_savings_ratio_milli: savings_ratio_milli(
baseline_provider_tokens,
treatment_provider_tokens,
),
quality_preserved: true,
quality_baseline_score_milli: 0,
quality_treatment_score_milli: 0,
measurement_method: MeasurementMethod::ProviderReported,
context_strategy: String::new(),
methodology_version: "savings-receipt-v1".to_owned(),
evidence_refs,
decision_refs,
signature: String::new(),
}
}
}
fn savings_ratio_milli(baseline_tokens: u64, treatment_tokens: u64) -> u16 {
if baseline_tokens == 0 {
return 0;
}
let avoided_tokens = baseline_tokens.saturating_sub(treatment_tokens) as u128;
((avoided_tokens * 1000) / baseline_tokens as u128).min(1000) as u16
}
#[cfg(test)]
mod tests {
use crate::{MoneyV1, SavingsObservationV1, UsageBreakdownV1};
#[test]
fn serialization_round_trip() {
let observation = SavingsObservationV1 {
observation_id: "obs-1".to_owned(),
provider_id: "provider".to_owned(),
model_id: "model".to_owned(),
original_usage: UsageBreakdownV1::default(),
actual_usage: UsageBreakdownV1::default(),
local_cost_estimate: MoneyV1 {
currency: "USD".to_owned(),
coefficient: 1,
scale: 4,
},
evidence_refs: Vec::new(),
observed_at: "2026-01-01T00:00:00Z".to_owned(),
runtime_version: "1.0.0".to_owned(),
sequence_number: 1,
};
let json = serde_json::to_string(&observation).expect("observation should serialize");
let decoded = serde_json::from_str(&json).expect("observation should deserialize");
assert_eq!(observation, decoded);
}
}
#[cfg(test)]
mod savings_receipt_tests {
use super::*;
use crate::PlanId;
fn id<T>(value: &str) -> T
where
T: std::str::FromStr,
T::Err: std::fmt::Debug,
{
value.parse().expect("valid identifier")
}
fn balance(provider_billed_tokens: u64) -> ContextBalanceV1 {
ContextBalanceV1 {
original_tokens: provider_billed_tokens,
materialized_tokens: provider_billed_tokens,
delivered_tokens: provider_billed_tokens,
provider_billed_tokens,
}
}
fn execution(
receipt_id: &str,
actual_cost_micros: u64,
provider_billed_tokens: u64,
) -> ExecutionReceiptV1 {
ExecutionReceiptV1 {
schema_version: 1,
receipt_id: id(receipt_id),
task_id: id("task-1"),
plan_id: PlanId::try_from("plan-1").expect("valid plan id"),
context_balance: balance(provider_billed_tokens),
fresh_input_tokens: provider_billed_tokens,
cached_input_tokens: 0,
output_tokens: 10,
reasoning_tokens: 0,
requested_model: "model-1".to_owned(),
selected_model: "model-1".to_owned(),
provider: "provider-1".to_owned(),
capability_id: None,
capability_version: None,
model_calls: 1,
retries: 0,
latency_ms: 10,
actual_cost_micros,
baseline_cost_micros: actual_cost_micros,
avoided_cost_micros: 0,
etpao_milli: 0,
outcome_ref: None,
knowledge_refs: Vec::new(),
decision_refs: vec!["decision-1".to_owned()],
evidence_refs: Vec::new(),
signature: "signature-1".to_owned(),
}
}
#[test]
fn serialization_round_trip() {
let receipt = SavingsReceiptV1 {
schema_version: 1,
savings_id: "savings-1".to_owned(),
task_id: id("task-1"),
baseline_receipt_id: id("receipt-baseline"),
treatment_receipt_id: id("receipt-treatment"),
baseline_cost_micros: 10_000,
treatment_cost_micros: 5_000,
avoided_cost_micros: 5_000,
baseline_tokens: balance(1_000),
treatment_tokens: balance(600),
token_savings_ratio_milli: 400,
quality_preserved: true,
quality_baseline_score_milli: 900,
quality_treatment_score_milli: 900,
measurement_method: MeasurementMethod::ProviderReported,
context_strategy: "semantic".to_owned(),
methodology_version: "method-v1".to_owned(),
evidence_refs: Vec::new(),
decision_refs: vec!["decision-1".to_owned()],
signature: "signature-1".to_owned(),
};
let json = serde_json::to_string(&receipt).expect("receipt should serialize");
let decoded: SavingsReceiptV1 =
serde_json::from_str(&json).expect("receipt should deserialize");
assert_eq!(receipt, decoded);
}
#[test]
fn validation_rejects_avoided_cost_above_baseline() {
let mut receipt = SavingsReceiptV1::compute_from_arms(
&execution("receipt-baseline", 1_000, 1_000),
&execution("receipt-treatment", 500, 500),
);
receipt.avoided_cost_micros = receipt.baseline_cost_micros + 1;
assert!(receipt.validate().is_err());
}
#[test]
fn compute_from_arms_uses_cost_and_token_deltas() {
let baseline = execution("receipt-baseline", 10_000, 1_000);
let treatment = execution("receipt-treatment", 6_000, 600);
let receipt = SavingsReceiptV1::compute_from_arms(&baseline, &treatment);
assert_eq!(receipt.task_id, baseline.task_id);
assert_eq!(receipt.baseline_receipt_id, baseline.receipt_id);
assert_eq!(receipt.treatment_receipt_id, treatment.receipt_id);
assert_eq!(receipt.baseline_cost_micros, 10_000);
assert_eq!(receipt.treatment_cost_micros, 6_000);
assert_eq!(receipt.avoided_cost_micros, 4_000);
assert_eq!(receipt.token_savings_ratio_milli, 400);
assert_eq!(receipt.baseline_tokens, baseline.context_balance);
assert_eq!(receipt.treatment_tokens, treatment.context_balance);
assert!(receipt.validate().is_ok());
}
}