kmp_application/memory/

ingest.rs

use std::collections::{BTreeMap, BTreeSet};
use std::time::{SystemTime, UNIX_EPOCH};

use kmp_domain::{
    DECLARED_FROM_RELATE_METHOD, INTENDED_NEW_LABEL_METADATA_KEY, MemoryRelationType,
    RelationSemanticClass, SearchSummary, SearchSummaryFault, SourceKind, label_resemblances,
};

use crate::ApplicationError;
use crate::commands::{UpdateContextChange, UpdateContextCommand};
use crate::memory::{
    LabelPolicy, MemoryAcceptedCounts, MemoryCoordinateData, MemoryData, MemoryDimensionData,
    MemoryIngestCommand, MemoryIngestOutcome, MemoryRelationData, ResemblingLabelData,
};

use super::dimension_registry::DimensionRegistry;
use super::ref_boundary::{
    validate_ref_token, validate_supplied_entry_ref, validate_supplied_evidence_ref,
    validate_supplied_member_ref,
};

#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct ExistingMemoryRefs {
    pub refs: BTreeSet<String>,
    pub dimensions: BTreeSet<String>,
    /// The about's catalogue as `(kind, bare scope id)` pairs: what a new
    /// label is compared against before it is written.
    pub labels: BTreeSet<(String, String)>,
    /// Refs of other abouts the service verified exist before this ingest,
    /// for the one relation that may cross an about: an equivalence a
    /// writer declared from a `kmp_relate` proposal.
    pub foreign: BTreeSet<String>,
    /// Highest committed sequence for each `(dimension, scope_id)` coordinate.
    /// An absent writer sequence is assigned from this frontier at ingest.
    pub max_sequences: BTreeMap<(String, String), u32>,
}

pub fn translate_memory_ingest(
    command: &MemoryIngestCommand,
    existing: &ExistingMemoryRefs,
) -> Result<(UpdateContextCommand, MemoryIngestOutcome), ApplicationError> {
    validate_command(command)?;
    let ingested_at = kernel_ingested_at();
    let resolved;
    let accepted_command = if command.default_observation_to_ingestion {
        resolved = super::observation_defaults::resolve(command, &ingested_at);
        &resolved
    } else {
        command
    };
    let memory = namespaced_memory(
        &command.about,
        &accepted_command.memory,
        existing,
        &ingested_at,
        accepted_command
            .provenance
            .as_ref()
            .and_then(|p| p.observed_at.as_deref()),
    )?;
    // A dimension declared here that the about did not hold yet is a label
    // this write creates; the writer reports it so vocabulary growth is
    // seen at the moment it happens rather than discovered later.
    let created_dimensions = memory
        .dimensions
        .iter()
        .map(|dimension| dimension.id.clone())
        .filter(|id| !existing.dimensions.contains(id))
        .collect::<Vec<_>>();
    // Does one resemble it? A new label is folded and compared against the
    // catalogue; the kernel never renames in silence. Under REFUSE the match
    // is a refusal that names both labels, unless the writer marked the
    // dimension as intended new; under WARN it is written and said.
    let resembling_labels = resembling_labels(&command.about, &command.memory, existing)?;
    if command.label_policy == LabelPolicy::Refuse && !resembling_labels.is_empty() {
        return Err(ApplicationError::Validation(format!(
            "labels resemble ones the about already holds: {}. Reuse the existing label, or set the dimension metadata `{}: \"true\"` to insist on the new one",
            resembling_labels
                .iter()
                .map(|label| label.why.clone())
                .collect::<Vec<_>>()
                .join(" "),
            INTENDED_NEW_LABEL_METADATA_KEY
        )));
    }
    let mut warnings = search_summary_warnings(&command.memory);
    warnings.extend(resembling_labels.iter().map(|label| label.why.clone()));

    let mut changes = memory_changes(&memory)?;
    let mut outcome = MemoryIngestOutcome {
        neighborhood: None,
        replayed: false,
        clocks: Some(super::WriteClocks::for_memory(&memory)),
        receipt_ref: None,
        about: command.about.clone(),
        memory_id: memory_id_from_idempotency_key(&command.idempotency_key),
        accepted: MemoryAcceptedCounts {
            entries: command.memory.entries.len(),
            relations: command.memory.relations.len(),
            evidence: command.memory.evidence.len(),
        },
        read_after_write_ready: false,
        warnings,
        created_dimensions,
        resembling_labels,
    };

    if let Some(receipt) = super::receipt::receipt_change(accepted_command, &memory, &outcome)? {
        outcome.receipt_ref = Some(receipt.entity_id.clone());
        changes.push(receipt);
    }

    Ok((
        UpdateContextCommand {
            root_node_id: command.about.clone(),
            role: "memory".to_string(),
            work_item_id: command.idempotency_key.clone(),
            changes,
            expected_revision: None,
            expected_content_hash: None,
            idempotency_key: Some(command.idempotency_key.clone()),
            logical_digest: Some(logical_digest(command)),
            requested_by: command
                .provenance
                .as_ref()
                .map(|provenance| provenance.source_agent.clone()),
        },
        outcome,
    ))
}

/// The labels this ingest declares for the first time that resemble one the
/// about already holds, each with why. A dimension the about holds already
/// is a reuse and resembles nothing; one the writer marked as intended new
/// was compared by the writer and is left alone.
fn resembling_labels(
    about: &str,
    memory: &MemoryData,
    existing: &ExistingMemoryRefs,
) -> Result<Vec<ResemblingLabelData>, ApplicationError> {
    let catalogue = existing
        .labels
        .iter()
        .map(|(kind, value)| (kind.as_str(), value.as_str()))
        .collect::<Vec<_>>();
    let mut found = Vec::new();
    let mut registry = DimensionRegistry::new(about, existing)?;
    for dimension in &memory.dimensions {
        let value = registry.value(&dimension.kind, &dimension.id)?;
        let reference = registry.declare(&dimension.kind, &dimension.id)?;
        if existing.dimensions.contains(&reference) {
            continue;
        }
        if dimension
            .metadata
            .get(INTENDED_NEW_LABEL_METADATA_KEY)
            .is_some_and(|value| value == "true")
        {
            continue;
        }
        for resemblance in label_resemblances(&dimension.kind, &value, catalogue.iter().copied()) {
            found.push(ResemblingLabelData {
                key: resemblance.key().to_string(),
                value: resemblance.value().to_string(),
                existing_key: resemblance.existing_key().to_string(),
                existing_value: resemblance.existing_value().to_string(),
                kind: resemblance.kind().name().to_string(),
                why: resemblance.why(),
            });
        }
    }
    Ok(found)
}

fn validate_command(command: &MemoryIngestCommand) -> Result<(), ApplicationError> {
    require_non_empty(&command.about, "about")?;
    validate_ref_token("about", &command.about).map_err(ApplicationError::Validation)?;
    require_non_empty(&command.idempotency_key, "idempotency_key")?;
    if let Some(provenance) = command.provenance.as_ref() {
        SourceKind::parse(&provenance.source_kind).map_err(|error| {
            ApplicationError::Validation(format!(
                "memory provenance source_kind is invalid: {error}"
            ))
        })?;
        require_non_empty(&provenance.source_agent, "provenance.source_agent")?;
        if !command.default_observation_to_ingestion || provenance.observed_at.is_some() {
            require_non_empty(
                provenance.observed_at.as_deref().unwrap_or_default(),
                "provenance.observed_at",
            )?;
        }
    }

    Ok(())
}

fn namespaced_memory(
    about: &str,
    memory: &MemoryData,
    existing: &ExistingMemoryRefs,
    ingested_at: &str,
    observed_at: Option<&str>,
) -> Result<MemoryData, ApplicationError> {
    if memory.dimensions.is_empty() && existing.dimensions.is_empty() {
        return Err(ApplicationError::Validation(
            "memory.dimensions must not be empty when no existing memory dimensions are available"
                .to_string(),
        ));
    }
    if memory.entries.is_empty() {
        return Err(ApplicationError::Validation(
            "memory.entries must not be empty".to_string(),
        ));
    }

    let mut known_refs = existing.refs.clone();
    known_refs.extend(existing.dimensions.iter().cloned());
    // The about's own anchor is always a valid relation target. It is a real
    // node — the projection materialises it and hangs `records` and
    // `has_dimension` off it — but it was never in this set, so relating to
    // it was refused as an unknown ref. That made the first write to a fresh
    // about impossible: strict demands a relation, every ref inside the
    // about is being created by this very ingest, and the one thing that
    // certainly exists could not be named. (#14)
    known_refs.insert(about.to_string());
    let mut dimension_ids = existing.dimensions.clone();
    let mut dimension_registry = DimensionRegistry::new(about, existing)?;
    let mut declared_dimension_refs = BTreeSet::new();
    let mut max_sequences = existing.max_sequences.clone();
    let mut dimensions = Vec::new();
    for dimension in &memory.dimensions {
        require_non_empty(&dimension.id, "memory.dimensions[].id")?;
        require_non_empty(&dimension.kind, "memory.dimensions[].kind")?;
        let dimension_value = dimension_registry.value(&dimension.kind, &dimension.id)?;
        let dimension_ref = dimension_registry.declare(&dimension.kind, &dimension.id)?;
        insert_unique(
            &mut declared_dimension_refs,
            &dimension_ref,
            "memory dimension",
        )?;
        if existing.dimensions.contains(&dimension_ref) {
            known_refs.insert(dimension_ref);
            continue;
        }
        insert_unique(&mut dimension_ids, &dimension_ref, "memory dimension")?;
        known_refs.insert(dimension_ref.clone());

        let mut metadata = dimension.metadata.clone();
        // The writer's insistence is read at translation and never stored.
        metadata.remove(INTENDED_NEW_LABEL_METADATA_KEY);
        metadata
            .entry("memory_about".to_string())
            .or_insert_with(|| about.to_string());
        metadata
            .entry("memory_dimension_id".to_string())
            .or_insert_with(|| dimension_value.clone());
        dimensions.push(MemoryDimensionData {
            id: dimension_ref,
            kind: dimension.kind.clone(),
            title: dimension.title.clone(),
            metadata,
        });
    }

    let mut entry_ids = BTreeSet::new();
    let mut entries = Vec::new();
    for entry in &memory.entries {
        require_non_empty(&entry.id, "memory.entries[].id")?;
        validate_supplied_entry_ref(about, "memory.entries[].id", &entry.id)
            .map_err(ApplicationError::Validation)?;
        require_non_empty(&entry.kind, "memory.entries[].kind")?;
        require_non_empty(&entry.text, "memory.entries[].text")?;
        if entry.coordinates.is_empty() {
            return Err(ApplicationError::Validation(format!(
                "memory entry `{}` must include at least one coordinate",
                entry.id
            )));
        }
        insert_unique(&mut entry_ids, &entry.id, "memory entry")?;
        known_refs.insert(entry.id.clone());

        let mut coordinates = Vec::new();
        let mut memberships = BTreeSet::new();
        for coordinate in &entry.coordinates {
            let mut coordinate = normalize_coordinate(
                coordinate,
                "memory.entries[].coordinates[]",
                "memory entry",
                &dimension_registry,
            )?;
            coordinate
                .ingested_at
                .get_or_insert_with(|| ingested_at.to_string());
            let sequence_key = (coordinate.dimension.clone(), coordinate.scope_id.clone());
            if !memberships.insert(sequence_key.clone()) {
                return Err(ApplicationError::Validation(format!(
                    "memory entry `{}` repeats label `{}={}`",
                    entry.id, coordinate.dimension, coordinate.scope_id
                )));
            }
            let frontier = max_sequences.entry(sequence_key).or_default();
            match coordinate.sequence {
                Some(sequence) => *frontier = (*frontier).max(sequence),
                None => {
                    *frontier = frontier.checked_add(1).ok_or_else(|| {
                        ApplicationError::Validation(
                            "memory coordinate sequence space is exhausted".to_string(),
                        )
                    })?;
                    coordinate.sequence = Some(*frontier);
                }
            }
            coordinates.push(coordinate);
        }
        let mut entry = entry.clone();
        entry.coordinates = coordinates;
        entries.push(entry);
    }

    let mut relations = Vec::new();
    for relation in &memory.relations {
        require_non_empty(&relation.source_ref, "memory.relations[].source_ref")?;
        require_non_empty(&relation.target_ref, "memory.relations[].target_ref")?;
        require_non_empty(&relation.rel, "memory.relations[].rel")?;
        let relation_type = MemoryRelationType::new(&relation.rel).map_err(|error| {
            ApplicationError::Validation(format!("memory relation type is invalid: {error}"))
        })?;
        let semantic_class =
            RelationSemanticClass::parse(&relation.semantic_class).map_err(|error| {
                ApplicationError::Validation(format!("memory relation class is invalid: {error}"))
            })?;
        let source_ref = normalize_ref(&relation.source_ref, &dimension_registry)?;
        let target_ref = normalize_ref(&relation.target_ref, &dimension_registry)?;
        validate_supplied_member_ref(about, "memory.relations[].from", &source_ref)
            .map_err(ApplicationError::Validation)?;
        // The one relation that may cross an about: an equivalence a writer
        // declared from a `kmp_relate` proposal, with why and evidence, to a
        // ref the service verified exists. The edge lives here; the other
        // about does not change.
        let crosses_abouts = crosses_abouts(about, relation, &relation_type, &target_ref);
        if crosses_abouts {
            validate_ref_token("memory.relations[].to", &target_ref)
                .map_err(ApplicationError::Validation)?;
            if !existing.foreign.contains(&target_ref) {
                return Err(ApplicationError::Validation(format!(
                    "memory relation `{}` -> `{}` declares an equivalence with a ref no about holds",
                    relation.source_ref, relation.target_ref
                )));
            }
        } else {
            validate_supplied_member_ref(about, "memory.relations[].to", &target_ref)
                .map_err(ApplicationError::Validation)?;
        }
        if !known_refs.contains(&source_ref)
            || (!crosses_abouts && !known_refs.contains(&target_ref))
        {
            return Err(ApplicationError::Validation(format!(
                "memory relation `{}` -> `{}` references unknown refs",
                relation.source_ref, relation.target_ref
            )));
        }
        if semantic_class != RelationSemanticClass::Structural {
            if relation
                .confidence
                .as_deref()
                .unwrap_or("")
                .trim()
                .is_empty()
            {
                return Err(ApplicationError::Validation(
                    "non-structural memory relations require confidence".to_string(),
                ));
            }
            if relation.why.as_deref().unwrap_or("").trim().is_empty()
                && relation.evidence.as_deref().unwrap_or("").trim().is_empty()
            {
                return Err(ApplicationError::Validation(
                    "non-structural memory relations require why or evidence".to_string(),
                ));
            }
        }
        validate_positive_optional(relation.sequence, "memory.relations[].sequence")?;
        let mut coordinate = relation
            .coordinate
            .as_ref()
            .map(|coordinate| {
                normalize_coordinate(
                    coordinate,
                    "memory.relations[].coordinate",
                    "memory relation",
                    &dimension_registry,
                )
            })
            .transpose()?
            .map(|mut coordinate| {
                coordinate
                    .ingested_at
                    .get_or_insert_with(|| ingested_at.to_string());
                coordinate
            });
        // contains_entry is the stored coordinate itself. A redundant link
        // must retain the coordinate compiled from the entry, not replace
        // that edge with a coordinate-less upsert (#576).
        if relation_type.as_str() == "contains_entry" && coordinate.is_none() {
            coordinate = entries
                .iter()
                .find(|entry| entry.id == target_ref)
                .and_then(|entry| {
                    entry
                        .coordinates
                        .iter()
                        .find(|position| position.scope_id == source_ref)
                })
                .cloned();
            if coordinate.is_none() {
                return Err(ApplicationError::Validation(format!(
                    "contains_entry from `{source_ref}` to `{target_ref}` has no coordinate and no matching entry membership in this write; provide the coordinate or use kmp_relabel to change an existing memory's labels"
                )));
            }
        }
        let mut relation = relation.clone();
        if semantic_class != RelationSemanticClass::Structural {
            relation.clocks = Some(super::resolve_relation_clocks::resolve_relation_clocks(
                relation.clocks.as_ref(),
                relation.coordinate.as_ref(),
                observed_at,
                ingested_at,
            )?);
        }
        if semantic_class == RelationSemanticClass::Structural && relation.clocks.is_some() {
            return Err(ApplicationError::Validation(
                "structural relations carry their clocks in coordinate, not clocks".to_string(),
            ));
        }
        if semantic_class != RelationSemanticClass::Structural
            && let Some(coordinate) = coordinate.as_mut()
        {
            coordinate.occurred_at = None;
            coordinate.observed_at = None;
            coordinate.ingested_at = None;
            coordinate.valid_from = None;
            coordinate.valid_until = None;
        }
        relation.semantic_class = semantic_class.as_str().to_string();
        relation.source_ref = source_ref;
        relation.target_ref = target_ref;
        relation.decision_id = normalize_optional_member_ref(
            about,
            "memory.relations[].decision_id",
            relation.decision_id.as_deref(),
            &dimension_registry,
        )?;
        relation.caused_by_node_id = normalize_optional_member_ref(
            about,
            "memory.relations[].caused_by_node_id",
            relation.caused_by_node_id.as_deref(),
            &dimension_registry,
        )?;
        relation.rel = relation_type.as_str().to_string();
        relation.coordinate = coordinate;
        relations.push(relation);
    }

    let mut evidence_ids = BTreeSet::new();
    let mut evidence_items = Vec::new();
    for evidence in &memory.evidence {
        require_non_empty(&evidence.id, "memory.evidence[].id")?;
        validate_supplied_evidence_ref(about, "memory.evidence[].id", &evidence.id)
            .map_err(ApplicationError::Validation)?;
        require_non_empty(&evidence.text, "memory.evidence[].text")?;
        insert_unique(&mut evidence_ids, &evidence.id, "memory evidence")?;
        known_refs.insert(evidence.id.clone());
        let mut supports = Vec::new();
        for supported in &evidence.supports {
            require_non_empty(supported, "memory.evidence[].supports[]")?;
            let supported_ref = normalize_ref(supported, &dimension_registry)?;
            validate_supplied_member_ref(about, "memory.evidence[].supports[]", &supported_ref)
                .map_err(ApplicationError::Validation)?;
            if !known_refs.contains(&supported_ref) {
                return Err(ApplicationError::Validation(format!(
                    "memory evidence `{}` supports unknown ref `{supported}`",
                    evidence.id
                )));
            }
            supports.push(supported_ref);
        }
        let mut evidence = evidence.clone();
        evidence.supports = supports;
        if !evidence.supports.is_empty() {
            evidence.support_clocks = Some(super::EvidenceSupportClocks::resolve(
                evidence.support_clocks.as_ref(),
                observed_at,
                ingested_at,
            )?);
        }
        evidence_items.push(evidence);
    }

    Ok(MemoryData {
        dimensions,
        entries,
        relations,
        evidence: evidence_items,
    })
}

/// The English summaries this ingest carries that will not carry retrieval,
/// said now, while the writer that produced them can still fix them.
///
/// The verdict is not stored. The reader makes the same reading when it
/// ranks, so a summary that fails here is searched by nobody, and one that
/// passes is searched whoever wrote it.
fn search_summary_warnings(memory: &MemoryData) -> Vec<String> {
    memory
        .entries
        .iter()
        .filter_map(|entry| {
            let summary = entry.metadata.get(SearchSummary::METADATA_KEY)?;
            SearchSummary::lint(&entry.text, summary)
                .err()
                .map(|faults| {
                    format!(
                        "memory entry `{}` carries a {} that will not carry retrieval: {}",
                        entry.id,
                        SearchSummary::METADATA_KEY,
                        SearchSummaryFault::describe(&faults)
                    )
                })
        })
        .collect()
}

/// The commit clock in the same lexicographically sortable representation
/// already used by the kernel's temporal projection. Callers may restate an
/// earlier `ingested_at` during migration or replay; this value only fills an
/// absent clock.
fn kernel_ingested_at() -> String {
    let since_epoch = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap_or_default();
    format!(
        "unix:{:012}:{:09}",
        since_epoch.as_secs() + 100_000_000_000,
        since_epoch.subsec_nanos()
    )
}

/// Whether a relation is the one that may cross an about: `same_event_as`
/// or `same_entity_as`, evidential, with why and evidence, stamped as
/// declared from a `kmp_relate` proposal, to a ref this about does not own.
pub fn crosses_abouts(
    about: &str,
    relation: &MemoryRelationData,
    relation_type: &MemoryRelationType,
    target_ref: &str,
) -> bool {
    relation_type.may_cross_abouts()
        && validate_supplied_member_ref(about, "memory.relations[].to", target_ref).is_err()
        && relation.semantic_class.trim() == "evidential"
        && !relation
            .why
            .as_deref()
            .unwrap_or_default()
            .trim()
            .is_empty()
        && !relation
            .evidence
            .as_deref()
            .unwrap_or_default()
            .trim()
            .is_empty()
        && relation
            .method
            .as_deref()
            .is_some_and(|method| method.starts_with(DECLARED_FROM_RELATE_METHOD))
}

fn normalize_ref(value: &str, dimensions: &DimensionRegistry) -> Result<String, ApplicationError> {
    dimensions.member(value)
}

fn normalize_optional_member_ref(
    about: &str,
    path: &str,
    value: Option<&str>,
    dimensions: &DimensionRegistry,
) -> Result<Option<String>, ApplicationError> {
    value
        .map(|value| {
            let normalized = normalize_ref(value, dimensions)?;
            validate_supplied_member_ref(about, path, &normalized)
                .map_err(ApplicationError::Validation)?;
            Ok(normalized)
        })
        .transpose()
}

fn normalize_coordinate(
    coordinate: &MemoryCoordinateData,
    field: &str,
    label: &str,
    dimensions: &DimensionRegistry,
) -> Result<MemoryCoordinateData, ApplicationError> {
    require_non_empty(&coordinate.dimension, &format!("{field}.dimension"))?;
    require_non_empty(&coordinate.scope_id, &format!("{field}.scope_id"))?;
    let scope_id = dimensions
        .coordinate(&coordinate.dimension, &coordinate.scope_id)
        .map_err(|error| ApplicationError::Validation(format!("{label} {field}: {error}")))?;
    validate_positive_optional(coordinate.sequence, &format!("{field}.sequence"))?;
    validate_positive_optional(coordinate.rank, &format!("{field}.rank"))?;

    let mut coordinate = coordinate.clone();
    coordinate.scope_id = scope_id;
    Ok(coordinate)
}

fn memory_changes(memory: &MemoryData) -> Result<Vec<UpdateContextChange>, ApplicationError> {
    let mut changes = Vec::new();
    for dimension in &memory.dimensions {
        changes.push(change(
            "memory_dimension",
            &dimension.id,
            serde_json::to_string(dimension),
            "KMP memory dimension ingest",
            vec![dimension.id.clone()],
        )?);
    }
    for entry in &memory.entries {
        let scopes = entry
            .coordinates
            .iter()
            .map(|coordinate| coordinate.scope_id.clone())
            .collect();
        changes.push(change(
            "memory_entry",
            &entry.id,
            serde_json::to_string(entry),
            "KMP memory entry ingest",
            scopes,
        )?);
    }
    for relation in &memory.relations {
        changes.push(change(
            "memory_relation",
            &format!(
                "relation:{}:{}:{}",
                relation.source_ref, relation.rel, relation.target_ref
            ),
            serde_json::to_string(relation),
            relation
                .why
                .as_deref()
                .filter(|value| !value.trim().is_empty())
                .unwrap_or("KMP memory relation ingest"),
            vec![relation.source_ref.clone(), relation.target_ref.clone()],
        )?);
    }
    for evidence in &memory.evidence {
        changes.push(change(
            "memory_evidence",
            &evidence.id,
            serde_json::to_string(evidence),
            evidence
                .source
                .as_deref()
                .filter(|value| !value.trim().is_empty())
                .unwrap_or("KMP memory evidence ingest"),
            evidence.supports.clone(),
        )?);
    }

    Ok(changes)
}

fn change(
    entity_kind: &str,
    entity_id: &str,
    payload: Result<String, serde_json::Error>,
    reason: &str,
    scopes: Vec<String>,
) -> Result<UpdateContextChange, ApplicationError> {
    Ok(UpdateContextChange {
        operation: "UPSERT".to_string(),
        entity_kind: entity_kind.to_string(),
        entity_id: entity_id.to_string(),
        payload_json: payload.map_err(|error| {
            ApplicationError::Validation(format!("memory payload could not serialize: {error}"))
        })?,
        reason: reason.to_string(),
        scopes,
    })
}

fn require_non_empty(value: &str, field: &str) -> Result<(), ApplicationError> {
    if value.trim().is_empty() {
        Err(ApplicationError::Validation(format!(
            "{field} cannot be empty"
        )))
    } else {
        Ok(())
    }
}

fn insert_unique(
    values: &mut BTreeSet<String>,
    value: &str,
    label: &str,
) -> Result<(), ApplicationError> {
    if !values.insert(value.to_string()) {
        Err(ApplicationError::Validation(format!(
            "duplicate {label} `{value}`"
        )))
    } else {
        Ok(())
    }
}

fn validate_positive_optional(value: Option<u32>, field: &str) -> Result<(), ApplicationError> {
    if value == Some(0) {
        Err(ApplicationError::Validation(format!(
            "{field} must be greater than zero when set"
        )))
    } else {
        Ok(())
    }
}

/// Digest of the logical ingest, taken before translation.
///
/// Translation consults existing state (a dimension already declared is not
/// re-created), so the same command translates differently after its own
/// first apply. This digest is computed from what the caller *said*, which is
/// the thing that must be equal for a replay to deserve a replayed answer.
pub(super) fn logical_digest(command: &MemoryIngestCommand) -> String {
    use sha2::{Digest, Sha256};
    let mut hasher = Sha256::new();
    if command.default_observation_to_ingestion {
        hasher.update(b"default_observation_to_ingestion\0");
    }
    hasher.update(command.about.as_bytes());
    hasher.update([0]);
    let memory = serde_json::to_vec(&command.memory)
        .expect("memory data serializes: it holds only strings, maps and integers");
    hasher.update(&memory);
    hasher.update([0]);
    if let Some(provenance) = &command.provenance {
        let provenance =
            serde_json::to_vec(provenance).expect("provenance serializes: it holds only strings");
        hasher.update(&provenance);
    }
    if let Some(context) = &command.receipt_context {
        hasher.update([0]);
        hasher.update(context.to_string().as_bytes());
    }
    format!("{:x}", hasher.finalize())
}

fn memory_id_from_idempotency_key(idempotency_key: &str) -> String {
    idempotency_key
        .strip_prefix("ingest:")
        .map(|suffix| format!("memory:{suffix}"))
        .unwrap_or_else(|| format!("memory:{idempotency_key}"))
}

#[cfg(test)]
mod tests {
    use std::collections::{BTreeMap, BTreeSet};

    use crate::ApplicationError;
    use crate::memory::{
        ExistingMemoryRefs, MemoryCoordinateData, MemoryData, MemoryDimensionData, MemoryEntryData,
        MemoryEvidenceData, MemoryIngestCommand, MemoryRelationData,
    };

    use super::translate_memory_ingest;

    #[test]
    fn translate_memory_ingest_creates_internal_memory_update_command() {
        let command = sample_command();

        let (update, outcome) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("valid memory should translate");

        assert_eq!(update.root_node_id, "question:830ce83f");
        assert_eq!(update.role, "memory");
        assert_eq!(update.idempotency_key.as_deref(), Some("ingest:app-test"));
        assert_eq!(outcome.memory_id, "memory:app-test");
        assert_eq!(outcome.accepted.entries, 1);
        assert_eq!(outcome.accepted.relations, 1);
        assert_eq!(outcome.accepted.evidence, 1);
        assert_eq!(
            update
                .changes
                .iter()
                .map(|change| change.entity_kind.as_str())
                .collect::<Vec<_>>(),
            vec![
                "memory_dimension",
                "memory_entry",
                "memory_relation",
                "memory_evidence"
            ]
        );
        assert_eq!(
            update.changes[0].entity_id,
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
        );
        assert_eq!(
            update.changes[1].scopes,
            ["label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"]
        );
        assert_eq!(
            update.changes[2].entity_id,
            "relation:label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12:contains_entry:question:830ce83f:claim:rachel-denver"
        );
        let entry_payload: serde_json::Value =
            serde_json::from_str(&update.changes[1].payload_json).expect("entry payload json");
        assert_eq!(
            entry_payload["coordinates"][0]["scope_id"],
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
        );
        assert!(
            entry_payload["coordinates"][0]["ingested_at"]
                .as_str()
                .is_some_and(|value| value.starts_with("unix:")),
            "the kernel must stamp when it learned every coordinate: {entry_payload}"
        );
    }

    /// A summary that will not carry retrieval is said at ingest, while the
    /// writer can still fix it. The verdict is not stored: the reader makes
    /// the same reading, so what is warned about here is what ranking will
    /// not search.
    #[test]
    fn translate_memory_ingest_warns_about_a_search_summary_that_will_not_carry() {
        let mut command = sample_command();
        command.memory.entries[0].text =
            "Rachel dijo que se mudaba a Denver por el ticket #469.".to_string();
        command.memory.entries[0].metadata.insert(
            "summary_en".to_string(),
            "Rachel said she was moving to Denver.".to_string(),
        );

        let (_, outcome) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("a degraded summary is a warning, not a refusal");

        assert_eq!(
            outcome.warnings,
            [
                "memory entry `question:830ce83f:claim:rachel-denver` carries a summary_en that will \
                 not carry retrieval: drops identifiers the text carries: #469"
            ]
        );
        assert_eq!(outcome.accepted.entries, 1);
    }

    #[test]
    fn translate_memory_ingest_is_silent_about_a_search_summary_that_carries() {
        let mut command = sample_command();
        command.memory.entries[0].text =
            "Rachel dijo que se mudaba a Denver por el ticket #469.".to_string();
        command.memory.entries[0].metadata.insert(
            "summary_en".to_string(),
            "Rachel said she was moving to Denver because of ticket #469.".to_string(),
        );

        let (update, outcome) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("a faithful summary translates");

        assert!(outcome.warnings.is_empty(), "{:?}", outcome.warnings);
        let entry_payload: serde_json::Value =
            serde_json::from_str(&update.changes[1].payload_json).expect("entry payload json");
        assert_eq!(
            entry_payload["metadata"]["summary_en"],
            "Rachel said she was moving to Denver because of ticket #469.",
            "the summary is stored as written, beside the text"
        );
    }

    #[test]
    fn translate_memory_ingest_preserves_a_replayed_ingest_clock() {
        let mut command = sample_command();
        command.memory.entries[0].coordinates[0].ingested_at =
            Some("2026-04-12T15:01:00Z".to_string());

        let (update, _) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("caller-supplied ingest clock should survive replay");
        let entry_payload: serde_json::Value =
            serde_json::from_str(&update.changes[1].payload_json).expect("entry payload json");

        assert_eq!(
            entry_payload["coordinates"][0]["ingested_at"],
            "2026-04-12T15:01:00Z"
        );
    }

    #[test]
    fn translate_memory_ingest_accepts_an_already_namespaced_dimension_id() {
        // Reads hand out the namespaced form, and the agent contract says to
        // copy identifiers back byte-for-byte. Wrapping it again would name a
        // second lane that reads back as the intended one.
        let namespaced =
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12";
        let mut command = sample_command();
        command.memory.dimensions[0].id = namespaced.to_string();
        command.memory.entries[0].coordinates[0].scope_id = namespaced.to_string();
        command.memory.relations[0].source_ref = namespaced.to_string();

        let (update, _) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("a namespaced dimension id belongs to this about");

        assert_eq!(update.changes[0].entity_id, namespaced);
        let entry_payload: serde_json::Value =
            serde_json::from_str(&update.changes[1].payload_json).expect("entry payload json");
        assert_eq!(entry_payload["coordinates"][0]["scope_id"], namespaced);
    }

    #[test]
    fn translate_memory_ingest_rejects_a_dimension_owned_by_another_about() {
        let mut command = sample_command();
        command.memory.dimensions[0].id =
            "label:v1:question%3Aother:conversation:conversation%3Arachel-2026-04-12".to_string();

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("a foreign about's dimension is not ours to write");

        assert_validation_contains(error, "belongs to another about");
    }

    #[test]
    fn translate_memory_ingest_fails_fast_for_unknown_coordinate_dimension() {
        let mut command = sample_command();
        command.memory.entries[0].coordinates[0].scope_id = "conversation:missing".to_string();

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("unknown scope should fail");

        assert_validation_contains(error, "unknown dimension");
    }

    #[test]
    fn translate_memory_ingest_rejects_coordinate_kind_mismatch() {
        let mut command = sample_command();
        command.memory.entries[0].coordinates[0].dimension = "ceremony".to_string();

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("coordinate kind mismatch should fail");

        assert_validation_contains(error, "unknown dimension `ceremony=");
    }

    #[test]
    fn translate_memory_ingest_rejects_relation_coordinate_kind_mismatch() {
        let mut command = sample_command();
        let mut coordinate = command.memory.entries[0].coordinates[0].clone();
        coordinate.dimension = "ceremony".to_string();
        command.memory.relations[0].coordinate = Some(coordinate);

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("relation coordinate kind mismatch should fail");

        assert_validation_contains(error, "unknown dimension `ceremony=");
    }

    #[test]
    fn translate_memory_ingest_fails_fast_for_unknown_relation_endpoint() {
        let mut command = sample_command();
        command.memory.relations[0].target_ref = "question:830ce83f:claim:missing".to_string();

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("unknown ref should fail");

        assert_validation_contains(error, "references unknown refs");
    }

    /// The first write to a fresh about has nothing of its own to relate to.
    ///
    /// Strict `kmp_write_memory` demands a relation, every ref inside the
    /// about is being created by the very ingest that declares it, and the
    /// one node that certainly exists — the about's own anchor, which the
    /// projection materialises and hangs `records` off — was refused as an
    /// unknown ref. That made seeding a new about impossible through the
    /// writer the skill presents as the default way to write. (#14)
    #[test]
    fn translate_memory_ingest_accepts_a_relation_to_the_abouts_own_anchor() {
        let mut command = sample_command();
        command.memory.relations[0].rel = "uses_background".to_string();
        command.memory.relations[0].semantic_class = "evidential".to_string();
        command.memory.relations[0].confidence = Some("high".to_string());
        command.memory.relations[0].why =
            Some("The linked memory supplies the observation's context.".to_string());

        command.memory.relations[0].target_ref = command.about.clone();

        let (update, _) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("an entry may relate to the about it belongs to");

        assert!(
            update
                .changes
                .iter()
                .any(|change| change.entity_id.ends_with(&command.about)),
            "the relation to the anchor must survive translation, got {:?}",
            update
                .changes
                .iter()
                .map(|change| change.entity_id.as_str())
                .collect::<Vec<_>>()
        );
    }

    #[test]
    fn translate_memory_ingest_canonicalizes_known_relation_types() {
        let mut command = sample_command();
        command.memory.relations[0].rel = " CONTAINS-ENTRY ".to_string();

        let (update, _) = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect("known relation aliases should canonicalize");

        assert_eq!(
            update.changes[2].entity_id,
            "relation:label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12:contains_entry:question:830ce83f:claim:rachel-denver"
        );
    }

    #[test]
    fn translate_memory_ingest_requires_non_structural_relation_proof() {
        let mut command = sample_command();
        command.memory.relations[0].semantic_class = "causal".to_string();
        command.memory.relations[0].why = None;
        command.memory.relations[0].evidence = None;
        command.memory.relations[0].confidence = None;

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("missing proof should fail");

        assert_validation_contains(error, "require confidence");
    }

    #[test]
    fn translate_memory_ingest_accepts_existing_materialized_refs() {
        let mut command = sample_command();
        command.memory.relations[0].rel = "uses_background".to_string();
        command.memory.relations[0].semantic_class = "evidential".to_string();
        command.memory.relations[0].confidence = Some("high".to_string());
        command.memory.relations[0].why =
            Some("The linked memory supplies the observation's context.".to_string());

        command.memory.dimensions.clear();
        command.memory.entries[0].coordinates[0].scope_id = "conversation:existing".to_string();
        command.memory.relations[0].source_ref = "conversation:existing".to_string();
        command.memory.relations[0].target_ref = "question:830ce83f:claim:existing".to_string();
        command.memory.evidence[0].supports = vec!["question:830ce83f:claim:existing".to_string()];
        let dimension_ref =
            "label:v1:question%3A830ce83f:conversation:conversation%3Aexisting".to_string();
        let existing = ExistingMemoryRefs {
            refs: [
                dimension_ref.clone(),
                "question:830ce83f:claim:existing".to_string(),
            ]
            .into_iter()
            .collect(),
            dimensions: [dimension_ref].into_iter().collect(),
            labels: BTreeSet::new(),
            ..ExistingMemoryRefs::default()
        };

        let (update, outcome) =
            translate_memory_ingest(&command, &existing).expect("existing refs should validate");

        assert_eq!(outcome.accepted.entries, 1);
        assert_eq!(update.changes.len(), 3);
    }

    #[test]
    fn translate_memory_ingest_treats_existing_namespaced_dimension_as_idempotent() {
        let command = sample_command();
        let dimension_ref =
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
                .to_string();
        let existing = ExistingMemoryRefs {
            refs: [dimension_ref.clone()].into_iter().collect(),
            dimensions: [dimension_ref.clone()].into_iter().collect(),
            labels: BTreeSet::new(),
            ..ExistingMemoryRefs::default()
        };

        let (update, outcome) = translate_memory_ingest(&command, &existing)
            .expect("existing dimension declaration should be idempotent");

        assert_eq!(outcome.accepted.entries, 1);
        assert_eq!(
            update
                .changes
                .iter()
                .map(|change| change.entity_kind.as_str())
                .collect::<Vec<_>>(),
            vec!["memory_entry", "memory_relation", "memory_evidence"]
        );
        assert_eq!(
            update.changes[0].scopes,
            std::slice::from_ref(&dimension_ref)
        );
        assert_eq!(
            update.changes[1].entity_id,
            "relation:label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12:contains_entry:question:830ce83f:claim:rachel-denver"
        );
    }

    #[test]
    fn translate_memory_ingest_keeps_existing_dimensions_as_known_relation_refs() {
        let mut command = sample_command();
        command.memory.dimensions.clear();
        let dimension_ref =
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
                .to_string();
        command.memory.relations[0].source_ref = dimension_ref.clone();
        let existing = ExistingMemoryRefs {
            refs: BTreeSet::new(),
            dimensions: [dimension_ref].into_iter().collect(),
            labels: BTreeSet::new(),
            ..ExistingMemoryRefs::default()
        };

        translate_memory_ingest(&command, &existing)
            .expect("existing dimensions should also be valid relation refs");
    }

    #[test]
    fn translate_memory_ingest_rejects_zero_coordinates_when_set() {
        let mut command = sample_command();
        command.memory.entries[0].coordinates[0].sequence = Some(0);

        let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("zero coordinate sequence should fail");

        assert_validation_contains(error, "sequence must be greater than zero");
    }

    #[test]
    fn translate_memory_ingest_assigns_next_sequence_when_writer_omits_it() {
        let mut command = sample_command();
        command.memory.entries[0].coordinates[0].sequence = None;
        let scope = "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
            .to_string();
        let existing = ExistingMemoryRefs {
            max_sequences: BTreeMap::from([(("conversation".to_string(), scope), 7)]),
            ..ExistingMemoryRefs::default()
        };

        let (update, _) = translate_memory_ingest(&command, &existing)
            .expect("kernel should assign the next coordinate sequence");
        let entry = update
            .changes
            .iter()
            .find(|change| change.entity_kind == "memory_entry")
            .expect("entry change");
        let payload: serde_json::Value =
            serde_json::from_str(&entry.payload_json).expect("entry payload");

        assert_eq!(payload["coordinates"][0]["sequence"], 8);
    }

    #[test]
    fn translate_memory_ingest_bounds_every_caller_supplied_ref_field() {
        const HOSTILE_REFS: &[&str] = &[
            "incident:gamma:entry:observation:foreign",
            "incident:beta",
            "incident:alfa:entry:x\nincident:beta:entry:y",
            "../../incident:beta:entry:x",
        ];
        const REF_FIELDS: &[&str] = &[
            "entry.id",
            "relation.from",
            "relation.to",
            "relation.decision_id",
            "relation.caused_by_node_id",
            "evidence.id",
            "evidence.supports",
        ];

        for field in REF_FIELDS {
            for hostile in HOSTILE_REFS {
                let mut command = sample_command();
                command.about = "incident:alfa".to_string();
                command.memory.entries[0].id = "incident:alfa:entry:observation:local".to_string();
                command.memory.relations[0].target_ref = command.memory.entries[0].id.clone();
                command.memory.evidence[0].id =
                    "evidence:incident:alfa:entry:observation:local:current".to_string();
                command.memory.evidence[0].supports = vec![command.memory.entries[0].id.clone()];

                match *field {
                    "entry.id" => command.memory.entries[0].id = (*hostile).to_string(),
                    "relation.from" => {
                        command.memory.relations[0].source_ref = (*hostile).to_string()
                    }
                    "relation.to" => {
                        command.memory.relations[0].target_ref = (*hostile).to_string()
                    }
                    "relation.decision_id" => {
                        command.memory.relations[0].decision_id = Some((*hostile).to_string())
                    }
                    "relation.caused_by_node_id" => {
                        command.memory.relations[0].caused_by_node_id = Some((*hostile).to_string())
                    }
                    "evidence.id" => command.memory.evidence[0].id = (*hostile).to_string(),
                    "evidence.supports" => {
                        command.memory.evidence[0].supports[0] = (*hostile).to_string()
                    }
                    unexpected => panic!("unknown test field {unexpected}"),
                }

                let error = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
                    .expect_err("an ingest ref outside the about must be refused");
                assert_validation_contains(
                    error,
                    if hostile.contains('/') || hostile.contains('\n') {
                        "memory refs cannot contain"
                    } else {
                        "does not belong to about"
                    },
                );
            }
        }
    }

    fn catalogue_with(kind: &str, value: &str) -> ExistingMemoryRefs {
        ExistingMemoryRefs {
            labels: BTreeSet::from([(kind.to_string(), value.to_string())]),
            ..ExistingMemoryRefs::default()
        }
    }

    #[test]
    fn a_lax_ingest_writes_a_resembling_label_and_says_so() {
        let command = sample_command();
        let existing = catalogue_with("conversation", "conversation-rachel-2026-04-12");

        let (_, outcome) =
            translate_memory_ingest(&command, &existing).expect("warn policy writes");

        assert_eq!(outcome.resembling_labels.len(), 1);
        let resembling = &outcome.resembling_labels[0];
        assert_eq!(resembling.key, "conversation");
        assert_eq!(resembling.value, "conversation:rachel-2026-04-12");
        assert_eq!(resembling.existing_value, "conversation-rachel-2026-04-12");
        assert_eq!(resembling.kind, "same_label_spelled_differently");
        assert!(
            outcome
                .warnings
                .iter()
                .any(|warning| warning == &resembling.why),
            "the why is also a warning: {:?}",
            outcome.warnings
        );
    }

    #[test]
    fn a_refusing_ingest_names_both_labels_and_the_way_to_insist() {
        let mut command = sample_command();
        command.label_policy = crate::memory::LabelPolicy::Refuse;
        let existing = catalogue_with("conversation", "conversation-rachel-2026-04-12");

        let error = translate_memory_ingest(&command, &existing).expect_err("refused");

        let message = match error {
            ApplicationError::Validation(message) => message,
            other => panic!("expected a validation error, got {other:?}"),
        };
        assert!(
            message.contains("`conversation=conversation:rachel-2026-04-12` resembles `conversation=conversation-rachel-2026-04-12`"),
            "{message}"
        );
        assert!(
            message.contains("same identifier up to case and separators"),
            "{message}"
        );
        assert!(message.contains("writer_intended_new"), "{message}");
    }

    #[test]
    fn an_insisted_label_is_left_alone_and_the_insistence_is_not_stored() {
        let mut command = sample_command();
        command.label_policy = crate::memory::LabelPolicy::Refuse;
        command.memory.dimensions[0]
            .metadata
            .insert("writer_intended_new".to_string(), "true".to_string());
        let existing = catalogue_with("conversation", "conversation-rachel-2026-04-12");

        let (update, outcome) =
            translate_memory_ingest(&command, &existing).expect("insisted label writes");

        assert!(outcome.resembling_labels.is_empty());
        assert!(
            !update.changes[0]
                .payload_json
                .contains("writer_intended_new"),
            "the marker is read at translation and never stored: {}",
            update.changes[0].payload_json
        );
    }

    #[test]
    fn a_label_the_about_already_holds_resembles_nothing() {
        let command = sample_command();
        let mut existing = catalogue_with("conversation", "conversation:rachel-2026-04-12");
        existing.dimensions.insert(
            "label:v1:question%3A830ce83f:conversation:conversation%3Arachel-2026-04-12"
                .to_string(),
        );

        let (_, outcome) = translate_memory_ingest(&command, &existing).expect("reuse");

        assert!(outcome.resembling_labels.is_empty());
        assert!(outcome.created_dimensions.is_empty());
    }

    fn sample_command() -> MemoryIngestCommand {
        MemoryIngestCommand {
            receipt_context: None,
            default_observation_to_ingestion: false,
            neighborhood_review: None,
            about: "question:830ce83f".to_string(),
            memory: MemoryData {
                dimensions: vec![MemoryDimensionData {
                    id: "conversation:rachel-2026-04-12".to_string(),
                    kind: "conversation".to_string(),
                    title: Some("Rachel relocation discussion".to_string()),
                    metadata: Default::default(),
                }],
                entries: vec![MemoryEntryData {
                    id: "question:830ce83f:claim:rachel-denver".to_string(),
                    kind: "claim".to_string(),
                    text: "Rachel said she was moving to Denver.".to_string(),
                    coordinates: vec![MemoryCoordinateData {
                        dimension: "conversation".to_string(),
                        scope_id: "conversation:rachel-2026-04-12".to_string(),
                        occurred_at: Some("2026-04-12T15:00:00Z".to_string()),
                        observed_at: None,
                        ingested_at: None,
                        valid_from: None,
                        valid_until: None,
                        sequence: Some(1),
                        rank: None,
                        metadata: Default::default(),
                    }],
                    metadata: Default::default(),
                }],
                relations: vec![MemoryRelationData {
                    clocks: None,
                    source_ref: "conversation:rachel-2026-04-12".to_string(),
                    target_ref: "question:830ce83f:claim:rachel-denver".to_string(),
                    rel: "contains_entry".to_string(),
                    semantic_class: "structural".to_string(),
                    why: None,
                    evidence: None,
                    confidence: None,
                    sequence: Some(1),
                    motivation: None,
                    method: None,
                    decision_id: None,
                    caused_by_node_id: None,
                    coordinate: None,
                }],
                evidence: vec![MemoryEvidenceData {
                    support_clocks: None,
                    id: "evidence:question:830ce83f:claim:rachel-denver".to_string(),
                    supports: vec!["question:830ce83f:claim:rachel-denver".to_string()],
                    text: "Conversation transcript line 1".to_string(),
                    source: Some("transcript:1".to_string()),
                    time: Some("2026-04-12T15:00:00Z".to_string()),
                    metadata: Default::default(),
                }],
            },
            provenance: None,
            idempotency_key: "ingest:app-test".to_string(),
            dry_run: false,
            label_policy: Default::default(),
        }
    }

    fn assert_validation_contains(error: ApplicationError, expected: &str) {
        match error {
            ApplicationError::Validation(message) => assert!(
                message.contains(expected),
                "expected `{message}` to contain `{expected}`"
            ),
            other => panic!("expected validation error, got {other:?}"),
        }
    }

    fn cross_about_relation(rel: &str, method: Option<&str>) -> MemoryRelationData {
        MemoryRelationData {
            clocks: None,
            source_ref: "question:830ce83f:claim:rachel-denver".to_string(),
            target_ref: "incident:platform:outcome:freeze".to_string(),
            rel: rel.to_string(),
            semantic_class: "evidential".to_string(),
            why: Some("Both record the same freeze.".to_string()),
            evidence: Some("kmp_relate proposal by identifier.".to_string()),
            confidence: Some("high".to_string()),
            sequence: None,
            motivation: None,
            method: method.map(str::to_string),
            decision_id: None,
            caused_by_node_id: None,
            coordinate: None,
        }
    }

    /// The one relation that may cross an about: an equivalence stamped as
    /// declared from a `kmp_relate` proposal, with why and evidence, to a
    /// ref the service verified exists. The edge is written here; the other
    /// about is untouched.
    #[test]
    fn a_declared_equivalence_crosses_the_about_and_nothing_else_does() {
        let mut command = sample_command();
        command.memory.relations.push(cross_about_relation(
            "same_event_as",
            Some("kmp_relate:identifier"),
        ));
        let mut existing = ExistingMemoryRefs::default();
        existing
            .foreign
            .insert("incident:platform:outcome:freeze".to_string());
        let (update, _) = translate_memory_ingest(&command, &existing)
            .expect("a declared equivalence is written");
        assert!(
            update.changes.iter().any(|change| {
                change.payload_json.contains("same_event_as")
                    && change
                        .payload_json
                        .contains("incident:platform:outcome:freeze")
            }),
            "the equivalence is among the changes"
        );

        let unverified = translate_memory_ingest(&command, &ExistingMemoryRefs::default())
            .expect_err("a ref no about holds is refused");
        assert!(
            unverified.to_string().contains("a ref no about holds"),
            "{unverified}"
        );

        let mut unstamped = sample_command();
        unstamped
            .memory
            .relations
            .push(cross_about_relation("same_event_as", None));
        let error = translate_memory_ingest(&unstamped, &existing)
            .expect_err("without the proposal stamp the boundary holds");
        assert!(
            error.to_string().contains("does not belong to about"),
            "{error}"
        );

        let mut follows = sample_command();
        follows.memory.relations.push(cross_about_relation(
            "follows",
            Some("kmp_relate:identifier"),
        ));
        let error = translate_memory_ingest(&follows, &existing)
            .expect_err("no other relation crosses an about");
        assert!(
            error.to_string().contains("does not belong to about"),
            "{error}"
        );
    }
}