ic_query/sns/report/model/reports/neurons/

reward.rs

//! Module: sns::report::model::reports::neurons::reward
//!
//! Responsibility: SNS reward-event and API-exhausted maturity checkpoint DTOs.
//! Does not own: live Governance calls, strict pagination, or filesystem loading.
//! Boundary: retains raw bracketing evidence, variable neuron evidence, and recomputed summaries.

use super::{
    SnsMaturityDisbursementRow, SnsNeuronPermissionRow,
    detail::{
        SnsPolicyObservationStatus, neuron_policy_observations, permission_code_is_assessable,
        permission_code_policy_observations, validate_canonical_principal,
        validate_maturity_disbursements, validate_neuron_permissions,
    },
};
use crate::{
    hex::is_lowercase_hex_32_bytes,
    report::ReportDataSource,
    sns::report::{
        MAINNET_SNS_WASM_CANISTER_ID, MainnetSnsCanisters, SNS_REWARD_CHECKPOINT_MAX_NEURONS,
        SNS_REWARD_CHECKPOINT_REPORT_SCHEMA_VERSION,
        model::reports::{SnsGovernanceParameters, SnsRunningVersionResponse},
    },
    subnet_catalog::MAINNET_NETWORK,
};
use ic_platform::candid::contract::{CandidType, serde::Deserialize};
use serde::Serialize;
use std::collections::HashSet;
use thiserror::Error as ThisError;

///
/// SnsRewardProposalId
///
/// Native proposal identifier retained in one Governance reward event.
///

#[derive(Clone, Debug, Eq, PartialEq, CandidType, Deserialize, Serialize)]
#[candid_path("ic_platform::candid::contract")]
#[serde(deny_unknown_fields)]
pub struct SnsRewardProposalId {
    /// Native SNS Governance proposal identifier.
    pub id: u64,
}

///
/// SnsRewardEvent
///
/// Complete native SNS Governance reward-event response.
///

#[derive(Clone, Debug, Eq, PartialEq, CandidType, Deserialize, Serialize)]
#[candid_path("ic_platform::candid::contract")]
#[serde(deny_unknown_fields)]
pub struct SnsRewardEvent {
    /// Number of reward rounds represented by this event when supplied.
    pub rounds_since_last_distribution: Option<u64>,
    /// Native timestamp at which distribution actually ran.
    pub actual_timestamp_seconds: u64,
    /// Canonical reward-event position when supplied.
    pub end_timestamp_seconds: Option<u64>,
    /// Total maturity available for distribution when supplied.
    pub total_available_e8s_equivalent: Option<u64>,
    /// Exact maturity amount distributed by this event.
    pub distributed_e8s_equivalent: u64,
    /// Deprecated native reward round retained as continuity evidence.
    pub round: u64,
    /// Complete settled-proposal identifiers retained from Governance.
    pub settled_proposals: Vec<SnsRewardProposalId>,
}

///
/// SnsRewardCollectionStatus
///
/// Authority level of one completed SNS reward checkpoint collection.
///

#[derive(Clone, Copy, Debug, Eq, PartialEq, Deserialize, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum SnsRewardCollectionStatus {
    /// The native neuron API was exhausted with stable bracket responses.
    ApiExhaustedObserved,
}

impl SnsRewardCollectionStatus {
    /// Return the stable report label for this collection status.
    #[must_use]
    pub const fn as_str(self) -> &'static str {
        match self {
            Self::ApiExhaustedObserved => "api_exhausted_observed",
        }
    }
}

///
/// SnsRewardCheckpointRow
///
/// Variable-size maturity and permission evidence for one observed SNS neuron.
///

#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct SnsRewardCheckpointRow {
    /// Exact 32-byte neuron identifier as lowercase hexadecimal text.
    pub neuron_id: String,
    /// Unix timestamp at which Governance reports the neuron was created.
    pub created_timestamp_seconds: u64,
    /// Raw unstaked maturity in e8s-equivalent units.
    pub maturity_e8s_equivalent: u64,
    /// Raw staked maturity in e8s-equivalent units when present.
    pub staked_maturity_e8s_equivalent: Option<u64>,
    /// Native automatic maturity-staking state when supplied.
    pub auto_stake_maturity: Option<bool>,
    /// Every current principal permission entry returned by Governance.
    pub permissions: Vec<SnsNeuronPermissionRow>,
    /// Every pending maturity disbursement returned by Governance.
    pub disburse_maturity_in_progress: Vec<SnsMaturityDisbursementRow>,
}

impl SnsRewardCheckpointRow {
    /// Recompute combined maturity from the two raw maturity components.
    #[must_use]
    pub fn checked_combined_maturity(&self) -> Option<u64> {
        self.maturity_e8s_equivalent
            .checked_add(self.staked_maturity_e8s_equivalent.unwrap_or(0))
    }

    /// Recompute both row-local maturity policy observations from raw evidence.
    #[must_use]
    pub fn derived_policy_observations(
        &self,
    ) -> (SnsPolicyObservationStatus, SnsPolicyObservationStatus) {
        neuron_policy_observations(
            &self.permissions,
            !self.disburse_maturity_in_progress.is_empty(),
        )
    }
}

///
/// SnsRewardCheckpointReport
///
/// Versioned API-exhausted observed SNS maturity checkpoint.
///

#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct SnsRewardCheckpointReport {
    /// Report schema version.
    pub schema_version: u32,
    /// Requested IC network identity.
    pub network: String,
    /// Stable mainnet SNS-W discovery canister identity.
    pub sns_wasm_canister_id: String,
    /// Explicit IC API endpoint used for every live call.
    pub source_endpoint: String,
    /// Collector identity recorded in report provenance.
    pub fetched_by: String,
    /// Current SNS-W list position retained only as display metadata.
    pub id: usize,
    /// Current SNS name retained only as display metadata.
    pub name: String,
    /// Complete deployed-SNS canister identity, serialized as flat fields.
    #[serde(flatten)]
    pub canisters: MainnetSnsCanisters,
    /// Explicit source classification; checkpoint reports are live-only.
    pub data_source: ReportDataSource,
    /// Unix timestamp captured immediately before targeted discovery.
    pub collection_started_at_unix_secs: u64,
    /// Unix timestamp captured after the final running-version bracket.
    pub collection_completed_at_unix_secs: u64,
    /// Number of neuron pages fetched, including the final exhaustion page.
    pub page_count: u32,
    /// Explicit authority classification for the completed collection.
    pub collection_status: SnsRewardCollectionStatus,
    /// Always false because Governance exposes no point-in-time neuron snapshot version.
    pub point_in_time_guaranteed: bool,
    /// Complete nervous-system parameters read before neuron pagination.
    pub parameters_before: SnsGovernanceParameters,
    /// Complete nervous-system parameters read after neuron pagination.
    pub parameters_after: SnsGovernanceParameters,
    /// Complete reward event read before neuron pagination.
    pub reward_event_before: SnsRewardEvent,
    /// Complete reward event read after neuron pagination.
    pub reward_event_after: SnsRewardEvent,
    /// Complete running-version response read before neuron pagination.
    pub running_version_before: SnsRunningVersionResponse,
    /// Complete running-version response read after neuron pagination.
    pub running_version_after: SnsRunningVersionResponse,
    /// Strictly increasing full neuron rows retained as raw checkpoint evidence.
    pub rows: Vec<SnsRewardCheckpointRow>,
}

///
/// SnsRewardCheckpointValidationError
///
/// Pure validation failure for untrusted serialized or in-memory checkpoint evidence.
///

#[derive(Debug, Eq, PartialEq, ThisError)]
#[error("invalid SNS reward checkpoint: {reason}")]
pub struct SnsRewardCheckpointValidationError {
    /// Deterministic invariant failure.
    pub reason: String,
}

/// Recompute and validate every checkpoint invariant available without live host calls.
pub fn validate_sns_reward_checkpoint_report(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    validate_checkpoint_evidence(report)?;
    report.summary().map(|_| ())
}

///
/// RewardCheckpointAssessment
///
/// Validation outcome retaining recomputed evidence from rejected checkpoints.
///

pub(in crate::sns::report) enum RewardCheckpointAssessment {
    Valid(SnsRewardCheckpointSummary),
    Invalid {
        error: SnsRewardCheckpointValidationError,
        summary: Option<SnsRewardCheckpointSummary>,
    },
}

impl RewardCheckpointAssessment {
    pub(in crate::sns::report) const fn summary(&self) -> Option<&SnsRewardCheckpointSummary> {
        match self {
            Self::Valid(summary) => Some(summary),
            Self::Invalid { summary, .. } => summary.as_ref(),
        }
    }
}

/// Retain recomputed evidence even when checkpoint validation fails during reconciliation.
pub(in crate::sns::report) fn assess_reward_checkpoint(
    report: &SnsRewardCheckpointReport,
) -> RewardCheckpointAssessment {
    let evidence = validate_checkpoint_evidence(report);
    match report.summary() {
        Ok(summary) => match evidence {
            Ok(()) => RewardCheckpointAssessment::Valid(summary),
            Err(error) => RewardCheckpointAssessment::Invalid {
                error,
                summary: Some(summary),
            },
        },
        Err(reason) => RewardCheckpointAssessment::Invalid {
            error: evidence.err().unwrap_or(reason),
            summary: None,
        },
    }
}

impl SnsRewardCheckpointReport {
    /// Derive checked totals and policy observations from the retained raw evidence.
    pub fn summary(
        &self,
    ) -> Result<SnsRewardCheckpointSummary, SnsRewardCheckpointValidationError> {
        recompute_reward_checkpoint_summary(&self.parameters_before, &self.rows)
            .map_err(invalid_validation)
    }

    /// Number of retained raw neuron rows.
    #[must_use]
    pub const fn row_count(&self) -> usize {
        self.rows.len()
    }

    /// Mandatory collection ceiling admitted from the raw parameter bracket.
    #[must_use]
    pub fn collection_row_ceiling(&self) -> Option<u64> {
        reward_checkpoint_neuron_ceiling(&self.parameters_before)
    }

    /// Targeted discovery, bracket and page calls implied by this collection protocol.
    #[must_use]
    pub const fn client_query_count(&self) -> Option<u32> {
        self.page_count.checked_add(8)
    }
}

fn validate_checkpoint_evidence(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    validate_checkpoint_header(report)?;
    validate_checkpoint_brackets(report)?;
    validate_checkpoint_rows(&report.rows, report.collection_completed_at_unix_secs)
}

fn validate_checkpoint_header(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    if report.schema_version != SNS_REWARD_CHECKPOINT_REPORT_SCHEMA_VERSION {
        return Err(invalid_validation(format!(
            "schema version {} does not equal {}",
            report.schema_version, SNS_REWARD_CHECKPOINT_REPORT_SCHEMA_VERSION
        )));
    }
    for (field, principal) in [
        ("sns_wasm_canister_id", report.sns_wasm_canister_id.as_str()),
        (
            "root_canister_id",
            report.canisters.root_canister_id.as_str(),
        ),
        (
            "governance_canister_id",
            report.canisters.governance_canister_id.as_str(),
        ),
        (
            "ledger_canister_id",
            report.canisters.ledger_canister_id.as_str(),
        ),
        (
            "swap_canister_id",
            report.canisters.swap_canister_id.as_str(),
        ),
        (
            "index_canister_id",
            report.canisters.index_canister_id.as_str(),
        ),
    ] {
        validate_canonical_principal(principal, field).map_err(invalid_validation)?;
    }
    let canister_ids = [
        report.sns_wasm_canister_id.as_str(),
        report.canisters.root_canister_id.as_str(),
        report.canisters.governance_canister_id.as_str(),
        report.canisters.ledger_canister_id.as_str(),
        report.canisters.swap_canister_id.as_str(),
        report.canisters.index_canister_id.as_str(),
    ];
    if canister_ids.into_iter().collect::<HashSet<_>>().len() != canister_ids.len() {
        return Err(invalid_validation(
            "checkpoint canister roles do not contain unique principals",
        ));
    }
    if report.sns_wasm_canister_id != MAINNET_SNS_WASM_CANISTER_ID {
        return Err(invalid_validation("unexpected SNS-W canister identity"));
    }
    if report.network != MAINNET_NETWORK {
        return Err(invalid_validation("checkpoint network must be ic"));
    }
    if report.source_endpoint.is_empty() || report.fetched_by.is_empty() {
        return Err(invalid_validation(
            "checkpoint source_endpoint and fetched_by must be non-empty",
        ));
    }
    if report.id == 0 || report.name.is_empty() {
        return Err(invalid_validation(
            "checkpoint SNS list id and display name must be non-empty",
        ));
    }
    if report.data_source != ReportDataSource::Live {
        return Err(invalid_validation("checkpoint data_source must be live"));
    }
    if report.point_in_time_guaranteed {
        return Err(invalid_validation(
            "checkpoint cannot claim a point-in-time neuron snapshot",
        ));
    }
    validate_checkpoint_collection_metadata(report)
}

fn validate_checkpoint_collection_metadata(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    if report.collection_completed_at_unix_secs < report.collection_started_at_unix_secs {
        return Err(invalid_validation(
            "collection completion precedes collection start",
        ));
    }
    if report.page_count == 0 {
        return Err(invalid_validation(
            "checkpoint must contain at least one page",
        ));
    }
    report
        .client_query_count()
        .ok_or_else(|| invalid_validation("page_count + 8 exceeds the native u32 contract"))?;
    let ceiling = report
        .collection_row_ceiling()
        .ok_or_else(|| invalid_validation("invalid max_number_of_neurons"))?;
    if u64::try_from(report.rows.len())
        .ok()
        .is_none_or(|rows| rows > ceiling)
    {
        return Err(invalid_validation(
            "raw row count exceeds the mandatory collection ceiling",
        ));
    }
    Ok(())
}

pub(in crate::sns::report) fn reward_checkpoint_neuron_ceiling(
    parameters: &SnsGovernanceParameters,
) -> Option<u64> {
    parameters
        .max_number_of_neurons
        .filter(|value| (1..=SNS_REWARD_CHECKPOINT_MAX_NEURONS).contains(value))
}

/// Return the first unstable component and its persisted-report diagnostic.
pub(in crate::sns::report) fn reward_checkpoint_bracket_mismatch(
    parameters: (&SnsGovernanceParameters, &SnsGovernanceParameters),
    events: (&SnsRewardEvent, &SnsRewardEvent),
    versions: (&SnsRunningVersionResponse, &SnsRunningVersionResponse),
) -> Option<(&'static str, &'static str)> {
    [
        (
            "nervous-system parameters",
            "nervous-system parameter brackets differ",
            parameters.0 == parameters.1,
        ),
        (
            "reward event",
            "reward-event brackets differ",
            events.0 == events.1,
        ),
        (
            "running SNS version",
            "running-version brackets differ",
            versions.0 == versions.1,
        ),
    ]
    .into_iter()
    .find_map(|(component, reason, stable)| (!stable).then_some((component, reason)))
}

fn validate_checkpoint_brackets(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    if let Some((_, reason)) = reward_checkpoint_bracket_mismatch(
        (&report.parameters_before, &report.parameters_after),
        (&report.reward_event_before, &report.reward_event_after),
        (
            &report.running_version_before,
            &report.running_version_after,
        ),
    ) {
        return Err(invalid_validation(reason));
    }
    validate_sns_reward_event_evidence(&report.reward_event_after).map_err(invalid_validation)?;
    validate_reward_event_position(report)?;
    validate_sns_reward_running_version_evidence(&report.running_version_after)
        .map_err(invalid_validation)?;
    validate_sns_reward_checkpoint_parameter_evidence(&report.parameters_after)
        .map_err(invalid_validation)
}

fn validate_reward_event_position(
    report: &SnsRewardCheckpointReport,
) -> Result<(), SnsRewardCheckpointValidationError> {
    let event = &report.reward_event_after;
    if event.actual_timestamp_seconds > report.collection_completed_at_unix_secs
        || event
            .end_timestamp_seconds
            .is_none_or(|end| end > report.collection_completed_at_unix_secs)
    {
        return Err(invalid_validation(
            "reward event timestamps exceed checkpoint collection completion",
        ));
    }
    Ok(())
}

fn validate_checkpoint_rows(
    rows: &[SnsRewardCheckpointRow],
    collection_completed_at_unix_secs: u64,
) -> Result<(), SnsRewardCheckpointValidationError> {
    let mut previous_id: Option<&str> = None;
    for row in rows {
        if !is_lowercase_hex_32_bytes(&row.neuron_id) {
            return Err(invalid_validation(format!(
                "neuron id {} is not 32-byte lowercase hexadecimal text",
                row.neuron_id
            )));
        }
        if previous_id.is_some_and(|previous| previous >= row.neuron_id.as_str()) {
            return Err(invalid_validation(
                "checkpoint neuron ids are not strictly increasing",
            ));
        }
        previous_id = Some(&row.neuron_id);
        if row.created_timestamp_seconds > collection_completed_at_unix_secs {
            return Err(invalid_validation(format!(
                "neuron {} creation timestamp exceeds collection completion",
                row.neuron_id
            )));
        }
        validate_neuron_permissions(&row.permissions, false)
            .map_err(|reason| invalid_validation(format!("neuron {}: {reason}", row.neuron_id)))?;
        validate_maturity_disbursements(&row.disburse_maturity_in_progress)
            .map_err(invalid_validation)?;
    }
    Ok(())
}

pub(in crate::sns::report) fn validate_sns_reward_running_version_evidence(
    response: &SnsRunningVersionResponse,
) -> Result<(), String> {
    let deployed = response
        .deployed_version
        .as_ref()
        .ok_or_else(|| "running version has no deployed_version".to_string())?;
    deployed.validate_hashes("deployed_version", Some(32))?;
    if let Some(target) = response
        .pending_version
        .as_ref()
        .and_then(|pending| pending.target_version.as_ref())
    {
        target.validate_hashes("pending_version.target_version", Some(32))?;
    }
    Ok(())
}

pub(in crate::sns::report) fn validate_sns_reward_checkpoint_parameter_evidence(
    parameters: &SnsGovernanceParameters,
) -> Result<(), String> {
    validate_default_followees(parameters)?;
    validate_parameter_permissions(parameters)
}

fn validate_default_followees(parameters: &SnsGovernanceParameters) -> Result<(), String> {
    let Some(defaults) = parameters.default_followees.as_ref() else {
        return Ok(());
    };
    let mut function_ids = HashSet::new();
    for row in &defaults.followees {
        if !function_ids.insert(row.function_id) {
            return Err("default followees contain a duplicate function id".to_string());
        }
        let mut neuron_ids = HashSet::new();
        for id in &row.followee_neuron_ids {
            if !is_lowercase_hex_32_bytes(id) {
                return Err("default followees contain a non-canonical neuron id".to_string());
            }
            if !neuron_ids.insert(id) {
                return Err("default followees contain a duplicate neuron id".to_string());
            }
        }
    }
    Ok(())
}

fn validate_parameter_permissions(parameters: &SnsGovernanceParameters) -> Result<(), String> {
    for (field, permissions) in [
        (
            "neuron_claimer_permissions",
            parameters.neuron_claimer_permissions.as_ref(),
        ),
        (
            "neuron_grantable_permissions",
            parameters.neuron_grantable_permissions.as_ref(),
        ),
    ] {
        let Some(permissions) = permissions else {
            continue;
        };
        let mut codes = HashSet::new();
        if permissions
            .permissions
            .iter()
            .any(|code| !codes.insert(*code))
        {
            return Err(format!("{field} contains a duplicate permission code"));
        }
    }
    Ok(())
}

pub(in crate::sns::report) fn validate_sns_reward_event_evidence(
    event: &SnsRewardEvent,
) -> Result<(), String> {
    if event.end_timestamp_seconds.is_none() {
        return Err("reward event is missing canonical end_timestamp_seconds".to_string());
    }
    let mut proposal_ids = HashSet::new();
    if event
        .settled_proposals
        .iter()
        .any(|proposal| !proposal_ids.insert(proposal.id))
    {
        return Err("reward event contains duplicate settled proposal ids".to_string());
    }
    Ok(())
}

fn invalid_validation(reason: impl Into<String>) -> SnsRewardCheckpointValidationError {
    SnsRewardCheckpointValidationError {
        reason: reason.into(),
    }
}

///
/// SnsRewardCheckpointSummary
///
/// Pure recomputation result derived from raw checkpoint parameters and rows.
///

#[derive(Clone, Debug, Eq, PartialEq, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
pub struct SnsRewardCheckpointSummary {
    /// Checked aggregate unstaked maturity across every row.
    pub aggregate_maturity_e8s_equivalent: u64,
    /// Checked aggregate staked maturity across every row.
    pub aggregate_staked_maturity_e8s_equivalent: u64,
    /// Checked aggregate combined maturity across every row.
    pub aggregate_combined_maturity_e8s_equivalent: u64,
    /// Number of principal permission entries observed across every row.
    pub permission_entry_count: usize,
    /// Number of raw unknown or anomalous permission codes observed globally and per-neuron.
    pub unassessable_permission_code_count: usize,
    /// Number of pending maturity disbursements observed across every row.
    pub pending_maturity_disbursement_count: usize,
    /// Number of neurons with automatic maturity staking enabled.
    pub auto_stake_maturity_enabled_count: usize,
    /// Number of neurons with automatic maturity staking explicitly disabled.
    pub auto_stake_maturity_disabled_count: usize,
    /// Number of neurons without an automatic maturity-staking value.
    pub auto_stake_maturity_unspecified_count: usize,
    /// Whether permission 2 is currently grantable, or unknown when the list is missing.
    pub manage_principals_grantable: Option<bool>,
    /// Global observation for disabling permissions 7 and 8 and pending disbursements.
    pub maturity_mint_conversion_observed_disabled: SnsPolicyObservationStatus,
    /// Global observation for disabling manual maturity-staking permission 9.
    pub manual_maturity_staking_observed_disabled: SnsPolicyObservationStatus,
    /// Combined observed maturity-conversion policy status.
    pub maturity_conversion_policy_observed_status: SnsPolicyObservationStatus,
}

pub(in crate::sns::report) fn recompute_reward_checkpoint_summary(
    parameters: &SnsGovernanceParameters,
    rows: &[SnsRewardCheckpointRow],
) -> Result<SnsRewardCheckpointSummary, String> {
    let mut summary = SnsRewardCheckpointSummary {
        aggregate_maturity_e8s_equivalent: 0,
        aggregate_staked_maturity_e8s_equivalent: 0,
        aggregate_combined_maturity_e8s_equivalent: 0,
        permission_entry_count: 0,
        unassessable_permission_code_count: 0,
        pending_maturity_disbursement_count: 0,
        auto_stake_maturity_enabled_count: 0,
        auto_stake_maturity_disabled_count: 0,
        auto_stake_maturity_unspecified_count: 0,
        manage_principals_grantable: parameters
            .neuron_grantable_permissions
            .as_ref()
            .map(|permissions| permissions.permissions.contains(&2)),
        maturity_mint_conversion_observed_disabled: SnsPolicyObservationStatus::ObservedSatisfied,
        manual_maturity_staking_observed_disabled: SnsPolicyObservationStatus::ObservedSatisfied,
        maturity_conversion_policy_observed_status: SnsPolicyObservationStatus::ObservedSatisfied,
    };
    let (parameter_mint, parameter_staking, parameter_unknown_count) =
        parameter_policy_observations(parameters);
    summary.maturity_mint_conversion_observed_disabled = parameter_mint;
    summary.manual_maturity_staking_observed_disabled = parameter_staking;
    summary.unassessable_permission_code_count = parameter_unknown_count;

    for row in rows {
        accumulate_reward_row(&mut summary, row)?;
    }
    summary.maturity_conversion_policy_observed_status = summary
        .maturity_mint_conversion_observed_disabled
        .combine(summary.manual_maturity_staking_observed_disabled);
    Ok(summary)
}

fn accumulate_reward_row(
    summary: &mut SnsRewardCheckpointSummary,
    row: &SnsRewardCheckpointRow,
) -> Result<(), String> {
    let combined = row.checked_combined_maturity().ok_or_else(|| {
        format!(
            "neuron {} combined maturity exceeds the native u64 contract",
            row.neuron_id
        )
    })?;
    let (row_mint, row_staking) = row.derived_policy_observations();
    summary.aggregate_maturity_e8s_equivalent = checked_sum(
        summary.aggregate_maturity_e8s_equivalent,
        row.maturity_e8s_equivalent,
        "aggregate maturity",
    )?;
    summary.aggregate_staked_maturity_e8s_equivalent = checked_sum(
        summary.aggregate_staked_maturity_e8s_equivalent,
        row.staked_maturity_e8s_equivalent.unwrap_or(0),
        "aggregate staked maturity",
    )?;
    summary.aggregate_combined_maturity_e8s_equivalent = checked_sum(
        summary.aggregate_combined_maturity_e8s_equivalent,
        combined,
        "aggregate combined maturity",
    )?;
    accumulate_reward_row_counts(summary, row)?;
    summary.maturity_mint_conversion_observed_disabled = summary
        .maturity_mint_conversion_observed_disabled
        .combine(row_mint);
    summary.manual_maturity_staking_observed_disabled = summary
        .manual_maturity_staking_observed_disabled
        .combine(row_staking);
    Ok(())
}

fn accumulate_reward_row_counts(
    summary: &mut SnsRewardCheckpointSummary,
    row: &SnsRewardCheckpointRow,
) -> Result<(), String> {
    summary.permission_entry_count = summary
        .permission_entry_count
        .checked_add(row.permissions.len())
        .ok_or_else(|| "permission entry count overflow".to_string())?;
    summary.pending_maturity_disbursement_count = summary
        .pending_maturity_disbursement_count
        .checked_add(row.disburse_maturity_in_progress.len())
        .ok_or_else(|| "pending maturity disbursement count overflow".to_string())?;
    summary.unassessable_permission_code_count = summary
        .unassessable_permission_code_count
        .checked_add(
            row.permissions
                .iter()
                .flat_map(|permission| permission.permission_types.iter())
                .filter(|value| !permission_code_is_assessable(**value))
                .count(),
        )
        .ok_or_else(|| "unassessable permission code count overflow".to_string())?;
    match row.auto_stake_maturity {
        Some(true) => increment(&mut summary.auto_stake_maturity_enabled_count)?,
        Some(false) => increment(&mut summary.auto_stake_maturity_disabled_count)?,
        None => increment(&mut summary.auto_stake_maturity_unspecified_count)?,
    }
    Ok(())
}

fn parameter_policy_observations(
    parameters: &SnsGovernanceParameters,
) -> (
    SnsPolicyObservationStatus,
    SnsPolicyObservationStatus,
    usize,
) {
    let mut mint = SnsPolicyObservationStatus::ObservedSatisfied;
    let mut staking = SnsPolicyObservationStatus::ObservedSatisfied;
    let mut unknown_count = 0;
    for permissions in [
        parameters.neuron_claimer_permissions.as_ref(),
        parameters.neuron_grantable_permissions.as_ref(),
    ] {
        let Some(permissions) = permissions else {
            mint = mint.combine(SnsPolicyObservationStatus::Unassessable);
            staking = staking.combine(SnsPolicyObservationStatus::Unassessable);
            continue;
        };
        if permissions.permissions.is_empty() {
            mint = mint.combine(SnsPolicyObservationStatus::Unassessable);
            staking = staking.combine(SnsPolicyObservationStatus::Unassessable);
        }
        for code in &permissions.permissions {
            let (code_mint, code_staking) = permission_code_policy_observations(*code);
            mint = mint.combine(code_mint);
            staking = staking.combine(code_staking);
            if !permission_code_is_assessable(*code) {
                unknown_count += 1;
            }
        }
    }
    (mint, staking, unknown_count)
}

fn checked_sum(left: u64, right: u64, field: &str) -> Result<u64, String> {
    left.checked_add(right)
        .ok_or_else(|| format!("{field} exceeds the native u64 contract"))
}

fn increment(value: &mut usize) -> Result<(), String> {
    *value = value
        .checked_add(1)
        .ok_or_else(|| "checkpoint count overflow".to_string())?;
    Ok(())
}