shepherd-core 6.6.0

The harness-agnostic shepherd engine: domain types, configuration schema, and run state. Knows nothing about any CLI, harness, or process.
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use alloc::{
    collections::{BTreeMap, BTreeSet},
    format,
    string::{String, ToString},
    vec::Vec,
};

use super::{
    PLAN_SCHEMA, PlanDocument, PlanError, PlanLane, PlanNode, PlanTopology, TOPOLOGY_SCHEMA,
    VerifiedPlanSeed,
};

const FOURTH_REJECTION: &str =
    "malignant-revoke-quarantine-preserve-evidence-no-resume-root-lineage-replacement";
const ROOT_CONTINUATION: &str = "fresh-root-preferred-new-run-binding-clears-child-authority";

pub fn validate_plan_structure(
    plan: &PlanDocument,
    seed: &VerifiedPlanSeed,
) -> Result<PlanTopology, PlanError> {
    let manifest = &plan.manifest;
    if manifest.schema != PLAN_SCHEMA {
        return Err(structure(format!(
            "schema must be `{PLAN_SCHEMA}`, found `{}`",
            manifest.schema
        )));
    }
    if manifest.run != seed.run || manifest.seed != seed.relative_path || manifest.mesh != seed.mesh
    {
        return Err(structure(
            "run, seed, and mesh must match the verified seed",
        ));
    }
    validate_identifier(&manifest.run, "run")?;
    validate_relative_path(&manifest.seed, "seed")?;
    validate_relative_path(&manifest.mesh, "mesh")?;
    validate_relative_path(&manifest.planning_evidence, "planning evidence")?;
    require_text(&manifest.goal, "goal")?;
    validate_closed_roles(manifest)?;

    let deliverables = unique_set(&manifest.deliverables, "deliverable")?;
    let seed_deliverables = unique_set(&seed.deliverables, "seed deliverable")?;
    if deliverables != seed_deliverables {
        return Err(structure(format!(
            "plan deliverables do not exactly cover verified seed deliverables: plan={deliverables:?} seed={seed_deliverables:?}"
        )));
    }
    let lanes = unique_set(&manifest.lanes, "lane")?;
    if lanes.is_empty() {
        return Err(structure("plan has zero lanes"));
    }
    for lane in &lanes {
        validate_identifier(lane, "lane")?;
    }
    validate_capacity(plan, seed, &lanes)?;

    let mut node_by_id = BTreeMap::new();
    let mut deliverable_producers: BTreeMap<&str, &str> = BTreeMap::new();
    let mut interface_producers: BTreeMap<&str, &str> = BTreeMap::new();
    for node in &manifest.nodes {
        validate_node(node, &lanes, &deliverables)?;
        if node_by_id.insert(node.id.as_str(), node).is_some() {
            return Err(structure(format!("duplicate node id `{}`", node.id)));
        }
        for deliverable in &node.seed_deliverables {
            if let Some(previous) = deliverable_producers.insert(deliverable, &node.id) {
                return Err(structure(format!(
                    "seed deliverable `{deliverable}` has duplicate producer nodes `{previous}` and `{}`",
                    node.id
                )));
            }
        }
        for interface in &node.produces {
            validate_interface(interface)?;
            if let Some(previous) = interface_producers.insert(interface, &node.id) {
                return Err(structure(format!(
                    "interface producer is duplicated for `{interface}` by `{previous}` and `{}`",
                    node.id
                )));
            }
        }
        for interface in &node.consumes {
            validate_interface(interface)?;
        }
    }
    for deliverable in &deliverables {
        if !deliverable_producers.contains_key(deliverable.as_str()) {
            return Err(structure(format!(
                "verified seed deliverable `{deliverable}` is uncovered"
            )));
        }
    }

    for node in &manifest.nodes {
        for dependency in &node.depends_on {
            if !node_by_id.contains_key(dependency.as_str()) {
                return Err(structure(format!(
                    "node `{}` has dangling dependency `{dependency}`",
                    node.id
                )));
            }
            if dependency == &node.id {
                return Err(structure(format!("dependency cycle at `{}`", node.id)));
            }
        }
    }
    let topological_order = topological_order(&node_by_id)?;
    validate_reachability(&node_by_id)?;
    validate_concurrent_ownership(&node_by_id)?;

    let cargo_targets = manifest
        .capacity
        .cargo_targets
        .iter()
        .map(|binding| (binding.lane.as_str(), binding.value.as_str()))
        .collect::<BTreeMap<_, _>>();
    let conductors = manifest
        .capacity
        .conductors
        .iter()
        .map(|binding| (binding.lane.as_str(), binding.value.as_str()))
        .collect::<BTreeMap<_, _>>();
    let mut topology_lanes = Vec::new();
    for lane in &manifest.lanes {
        let mut node_ids = manifest
            .nodes
            .iter()
            .filter(|node| &node.lane == lane)
            .map(|node| node.id.clone())
            .collect::<Vec<_>>();
        node_ids.sort();
        if node_ids.is_empty() {
            return Err(structure(format!("lane `{lane}` has zero nodes")));
        }
        let mut lane_deliverables = manifest
            .nodes
            .iter()
            .filter(|node| &node.lane == lane)
            .flat_map(|node| node.seed_deliverables.iter().cloned())
            .collect::<Vec<_>>();
        lane_deliverables.sort();
        lane_deliverables.dedup();
        if lane_deliverables.is_empty() {
            return Err(structure(format!(
                "lane `{lane}` is not vertical because it binds no seed deliverable"
            )));
        }
        topology_lanes.push(PlanLane {
            id: lane.clone(),
            conductor: conductors[lane.as_str()].to_string(),
            cargo_target: cargo_targets[lane.as_str()].to_string(),
            node_ids,
            deliverables: lane_deliverables,
        });
    }
    topology_lanes.sort_by(|left, right| left.id.cmp(&right.id));
    let mut nodes = manifest.nodes.clone();
    nodes.sort_by(|left, right| left.id.cmp(&right.id));
    for node in &mut nodes {
        node.seed_deliverables.sort();
        node.depends_on.sort();
        node.owns.sort();
        node.forbidden.sort();
        node.consumes.sort();
        node.produces.sort();
    }
    let mut projected_deliverables = manifest.deliverables.clone();
    projected_deliverables.sort();
    let mut capacity = manifest.capacity.clone();
    capacity
        .cargo_targets
        .sort_by(|left, right| left.lane.cmp(&right.lane));
    capacity
        .conductors
        .sort_by(|left, right| left.lane.cmp(&right.lane));
    for wave in &mut capacity.schedule {
        wave.lanes.sort();
    }
    capacity
        .schedule
        .sort_by(|left, right| left.lanes.cmp(&right.lanes));

    Ok(PlanTopology {
        schema: TOPOLOGY_SCHEMA.to_string(),
        run: manifest.run.clone(),
        seed: manifest.seed.clone(),
        mesh: manifest.mesh.clone(),
        planning_evidence: manifest.planning_evidence.clone(),
        goal: manifest.goal.clone(),
        deliverables: projected_deliverables,
        lanes: topology_lanes,
        nodes,
        topological_order,
        capacity,
        capacity_policy: capacity_policy(manifest.lanes.len()).to_string(),
    })
}

fn validate_closed_roles(manifest: &super::PlanManifestV2) -> Result<(), PlanError> {
    if manifest.root_roles != ["shepherd", "planter"] {
        return Err(structure(
            "root roles must be exactly `[shepherd, planter]` in that order",
        ));
    }
    if manifest.child_lead_roles != ["engineer", "conductor"] {
        return Err(structure(
            "child lead roles must be exactly `[engineer, conductor]` in that order",
        ));
    }
    if manifest.planning_lead != "engineer" || manifest.engineer_count != 1 {
        return Err(structure(
            "normal planning requires exactly one active Engineer child lead",
        ));
    }
    if manifest.review_rejection_limit != 3 || manifest.fourth_rejection != FOURTH_REJECTION {
        return Err(structure(
            "review custody requires three redos then fourth-rejection malignant revocation, quarantine, evidence preservation, no resume, and root-lineage replacement",
        ));
    }
    if manifest.root_continuation != ROOT_CONTINUATION {
        return Err(structure(
            "root continuation must prefer a fresh root and clear prior child authority under a new run binding before reuse",
        ));
    }
    Ok(())
}

fn validate_node(
    node: &PlanNode,
    lanes: &BTreeSet<String>,
    deliverables: &BTreeSet<String>,
) -> Result<(), PlanError> {
    validate_identifier(&node.id, "node id")?;
    if !lanes.contains(&node.lane) {
        return Err(structure(format!(
            "node `{}` names unknown lane `{}`",
            node.id, node.lane
        )));
    }
    for deliverable in &node.seed_deliverables {
        if !deliverables.contains(deliverable) {
            return Err(structure(format!(
                "node `{}` names unknown seed deliverable `{deliverable}`",
                node.id
            )));
        }
    }
    let expected_work = match node.role.as_str() {
        "coder" => "production",
        "worker" => "artifact",
        "engineer" => "planning",
        "auditor" | "critic" => "review",
        "discovery" => "research",
        "conductor" => "coordination",
        "shepherd" | "planter" => {
            return Err(structure(format!(
                "root role `{}` cannot be assigned a plan node",
                node.role
            )));
        }
        _ => return Err(structure(format!("invalid role `{}`", node.role))),
    };
    if node.work_kind != expected_work {
        let detail = if node.role == "conductor" {
            "Conductor consumes an immutable lane slice and may only coordinate; planning, rescoping, and implementation are forbidden"
        } else {
            "role and work kind are incompatible"
        };
        return Err(structure(format!(
            "node `{}`: {detail}; role `{}` requires work kind `{expected_work}`, found `{}`",
            node.id, node.role, node.work_kind
        )));
    }
    require_text(&node.outcome, &format!("node `{}` outcome", node.id))?;
    if node.owns.is_empty() {
        return Err(structure(format!("node `{}` owns is empty", node.id)));
    }
    for path in &node.owns {
        validate_relative_path(path, &format!("node `{}` owned path", node.id))?;
        if path == ".shepherd" || path.starts_with(".shepherd/") {
            return Err(structure(format!(
                "node `{}` cannot own native state or run evidence paths",
                node.id
            )));
        }
    }
    if node.forbidden.is_empty() {
        return Err(structure(format!("node `{}` forbidden is empty", node.id)));
    }
    for command in [&node.red.command, &node.green.command, &node.eval.command] {
        validate_argv(command, &node.id)?;
    }
    if node.red.expects != "failure" || node.green.expects != "success" {
        return Err(structure(format!(
            "node `{}` RED must expect failure and GREEN must expect success",
            node.id
        )));
    }
    require_text(&node.red.reason, "red reason")?;
    require_text(&node.green.reason, "green reason")?;
    if !matches!(node.eval.threshold, Some(1..=100)) {
        return Err(structure(format!(
            "node `{}` eval threshold must be an integer from 1 through 100",
            node.id
        )));
    }
    validate_relative_path(&node.evidence, "evidence")?;
    if !node.evidence.starts_with(".shepherd/runs/") {
        return Err(structure(format!(
            "node `{}` evidence must be run-relative",
            node.id
        )));
    }
    if !matches!(node.review.role.as_str(), "auditor" | "critic") {
        return Err(structure(format!(
            "node `{}` review role must be auditor or critic",
            node.id
        )));
    }
    require_text(&node.review.predicate, "review predicate")?;
    require_text(&node.failure_route, "failure_route")?;
    require_text(&node.rollback, "rollback")?;
    Ok(())
}

fn validate_capacity(
    plan: &PlanDocument,
    seed: &VerifiedPlanSeed,
    lanes: &BTreeSet<String>,
) -> Result<(), PlanError> {
    let capacity = &plan.manifest.capacity;
    if capacity.logical_lane_limit == 0
        || capacity.host_process_ceiling == 0
        || capacity.project_spawn_max_parallel == 0
        || capacity.plan_process_ceiling == 0
        || capacity.parent_role_cap == 0
        || capacity.run_budget == 0
        || capacity.simultaneous_process_ceiling == 0
        || capacity.per_lane_child_wave_ceiling == 0
        || capacity.model_quota == 0
        || capacity.disk_min_mib < 1024
    {
        return Err(structure(
            "capacity values must be nonzero and disk_min_mib at least 1024",
        ));
    }
    if capacity.logical_lane_limit > lanes.len() {
        return Err(structure(
            "capacity logical lane limit cannot exceed the authored lane count",
        ));
    }
    let effective = [
        capacity.host_process_ceiling,
        capacity.project_spawn_max_parallel,
        capacity.plan_process_ceiling,
        capacity.parent_role_cap,
        capacity.run_budget,
    ]
    .into_iter()
    .min()
    .expect("fixed nonempty ceiling set");
    if capacity.simultaneous_process_ceiling != effective {
        return Err(structure(
            "capacity simultaneous process ceiling must equal min(host, project spawn.max_parallel, plan, parent/role cap, run budget)",
        ));
    }
    // One logical lane contains its resident Conductor plus bounded children.
    // Live processes obey the five-way minimum above, not the lane count.
    if capacity.model_quota < capacity.simultaneous_process_ceiling {
        return Err(structure(
            "capacity model quota cannot be lower than the simultaneous process ceiling",
        ));
    }
    if !matches!(capacity.backpressure.as_str(), "queue" | "queue-fair") {
        return Err(structure(
            "capacity backpressure must be the deterministic `queue` or `queue-fair` policy",
        ));
    }
    validate_bindings(&capacity.cargo_targets, lanes, "cargo target", None)?;
    validate_bindings(&capacity.conductors, lanes, "conductor", Some("conductor"))?;

    if lanes.len() >= 4 && capacity.schedule.is_empty() {
        return Err(structure(
            "capacity schedule is required for four or more lanes",
        ));
    }
    let mut scheduled = BTreeSet::new();
    for wave in &capacity.schedule {
        if wave.lanes.is_empty()
            || wave.lanes.len() > capacity.logical_lane_limit
            || wave.process_slots == 0
            || wave.process_slots > capacity.simultaneous_process_ceiling
            || wave.process_slots
                > wave
                    .lanes
                    .len()
                    .saturating_mul(capacity.per_lane_child_wave_ceiling)
        {
            return Err(structure(
                "capacity schedule contains a zero or unsafe wave",
            ));
        }
        for lane in &wave.lanes {
            if !lanes.contains(lane) {
                return Err(structure(format!(
                    "capacity schedule names unknown lane `{lane}`"
                )));
            }
            if !scheduled.insert(lane.as_str()) {
                return Err(structure(format!(
                    "capacity schedule overlaps lane `{lane}`"
                )));
            }
        }
    }
    if !capacity.schedule.is_empty() && scheduled != lanes.iter().map(String::as_str).collect() {
        return Err(structure(
            "capacity schedule must cover every lane exactly once",
        ));
    }
    if lanes.len() >= 6 {
        let scale = capacity.scale_outcome.as_deref().ok_or_else(|| {
            structure("six or more lanes require an explicit scale outcome binding")
        })?;
        if !seed.outcomes.iter().any(|outcome| outcome == scale) {
            return Err(structure(format!(
                "scale outcome `{scale}` is not bound to a verified seed outcome"
            )));
        }
    }
    Ok(())
}

fn capacity_policy(lane_count: usize) -> &'static str {
    match lane_count {
        0..=1 => "small: minimize lanes; no arbitrary minimum",
        2 => "routine: two complete vertical Conductor subsprints",
        3 => "beefy: three complete vertical Conductor subsprints",
        4 => "beefy-mega boundary: explicit host and quota schedule required",
        5 => "mega: explicit host and quota schedule required",
        6 => "mega-exceptional boundary: seed-backed OS-scale reason and capacity proof required",
        7..=8 => "exceptional OS-scale: seed-backed reason and capacity proof required",
        _ => {
            "outside the 99 percent two-to-six envelope: no global cap; seed-backed OS-scale reason and capacity proof required"
        }
    }
}

fn validate_bindings(
    bindings: &[super::LaneBinding],
    lanes: &BTreeSet<String>,
    name: &str,
    exact_value: Option<&str>,
) -> Result<(), PlanError> {
    let mut bound_lanes = BTreeSet::new();
    let mut values = BTreeSet::new();
    for binding in bindings {
        if !lanes.contains(&binding.lane) || !bound_lanes.insert(binding.lane.as_str()) {
            return Err(structure(format!(
                "{name} bindings must name each lane exactly once"
            )));
        }
        validate_identifier(&binding.value, name)?;
        if let Some(exact) = exact_value {
            if binding.value != exact {
                return Err(structure(format!(
                    "{name} for `{}` must be `{exact}`",
                    binding.lane
                )));
            }
        } else if !values.insert(binding.value.as_str()) {
            return Err(structure(format!(
                "cargo target `{}` overlaps multiple lanes",
                binding.value
            )));
        }
    }
    if bound_lanes != lanes.iter().map(String::as_str).collect() {
        return Err(structure(format!(
            "{name} bindings must cover every lane exactly once"
        )));
    }
    Ok(())
}

fn topological_order(nodes: &BTreeMap<&str, &PlanNode>) -> Result<Vec<String>, PlanError> {
    let mut indegree = nodes
        .iter()
        .map(|(id, node)| (*id, node.depends_on.len()))
        .collect::<BTreeMap<_, _>>();
    let mut dependents: BTreeMap<&str, Vec<&str>> = BTreeMap::new();
    for (id, node) in nodes {
        for dependency in &node.depends_on {
            dependents.entry(dependency).or_default().push(id);
        }
    }
    let mut ready = indegree
        .iter()
        .filter_map(|(id, count)| (*count == 0).then_some(*id))
        .collect::<BTreeSet<_>>();
    let mut order = Vec::new();
    while let Some(id) = ready.pop_first() {
        order.push(id.to_string());
        if let Some(children) = dependents.get(id) {
            for child in children {
                let count = indegree.get_mut(child).expect("known dependent");
                *count -= 1;
                if *count == 0 {
                    ready.insert(child);
                }
            }
        }
    }
    if order.len() != nodes.len() {
        return Err(structure("dependency cycle detected"));
    }
    Ok(order)
}

fn validate_reachability(nodes: &BTreeMap<&str, &PlanNode>) -> Result<(), PlanError> {
    let mut reachable = BTreeSet::new();
    let mut pending = nodes
        .values()
        .filter(|node| !node.seed_deliverables.is_empty())
        .map(|node| node.id.as_str())
        .collect::<Vec<_>>();
    while let Some(id) = pending.pop() {
        if !reachable.insert(id) {
            continue;
        }
        pending.extend(nodes[id].depends_on.iter().map(String::as_str));
    }
    if let Some(id) = nodes.keys().find(|id| !reachable.contains(**id)) {
        return Err(structure(format!(
            "node `{id}` is unreachable from any seed deliverable"
        )));
    }
    Ok(())
}

fn validate_concurrent_ownership(nodes: &BTreeMap<&str, &PlanNode>) -> Result<(), PlanError> {
    let ids = nodes.keys().copied().collect::<Vec<_>>();
    for (index, left_id) in ids.iter().enumerate() {
        for right_id in &ids[index + 1..] {
            if depends_transitively(nodes, left_id, right_id)
                || depends_transitively(nodes, right_id, left_id)
            {
                continue;
            }
            for left in &nodes[left_id].owns {
                for right in &nodes[right_id].owns {
                    if paths_overlap(left, right) {
                        return Err(structure(format!(
                            "concurrently ready nodes `{left_id}` and `{right_id}` overlap owned paths `{left}` and `{right}`"
                        )));
                    }
                }
            }
        }
    }
    Ok(())
}

fn depends_transitively(nodes: &BTreeMap<&str, &PlanNode>, node: &str, target: &str) -> bool {
    let mut pending = nodes[node]
        .depends_on
        .iter()
        .map(String::as_str)
        .collect::<Vec<_>>();
    let mut seen = BTreeSet::new();
    while let Some(id) = pending.pop() {
        if id == target {
            return true;
        }
        if seen.insert(id) {
            pending.extend(nodes[id].depends_on.iter().map(String::as_str));
        }
    }
    false
}

fn paths_overlap(left: &str, right: &str) -> bool {
    left == right
        || left
            .strip_prefix(right)
            .is_some_and(|suffix| suffix.starts_with('/'))
        || right
            .strip_prefix(left)
            .is_some_and(|suffix| suffix.starts_with('/'))
}

fn validate_argv(argv: &[String], node: &str) -> Result<(), PlanError> {
    if argv.is_empty() {
        return Err(structure(format!("node `{node}` command argv is empty")));
    }
    let program = argv[0].as_str();
    if matches!(
        program,
        "sh" | "bash" | "zsh" | "fish" | "cmd" | "powershell" | "pwsh"
    ) || argv.iter().any(|argument| {
        argument.is_empty()
            || argument.contains('\n')
            || argument.contains("&&")
            || argument.contains(';')
            || argument == "|"
    }) {
        return Err(structure(format!(
            "node `{node}` command must be bounded argv without a shell"
        )));
    }
    Ok(())
}

fn validate_interface(value: &str) -> Result<(), PlanError> {
    let Some((id, version)) = value.rsplit_once('@') else {
        return Err(structure(format!(
            "interface `{value}` must carry `@version`"
        )));
    };
    validate_identifier(id, "interface id")?;
    if version.is_empty()
        || !version
            .bytes()
            .all(|byte| byte.is_ascii_alphanumeric() || byte == b'.')
    {
        return Err(structure(format!(
            "interface `{value}` has an invalid version"
        )));
    }
    Ok(())
}

fn unique_set(values: &[String], context: &str) -> Result<BTreeSet<String>, PlanError> {
    let mut set = BTreeSet::new();
    for value in values {
        validate_identifier(value, context)?;
        if !set.insert(value.clone()) {
            return Err(structure(format!("duplicate {context} `{value}`")));
        }
    }
    Ok(set)
}

fn validate_identifier(value: &str, context: &str) -> Result<(), PlanError> {
    if value.is_empty()
        || value.starts_with('-')
        || value.ends_with('-')
        || !value
            .bytes()
            .all(|byte| byte.is_ascii_lowercase() || byte.is_ascii_digit() || byte == b'-')
    {
        return Err(structure(format!("invalid {context} `{value}`")));
    }
    Ok(())
}

fn validate_relative_path(path: &str, context: &str) -> Result<(), PlanError> {
    validate_repository_path(path)
        .map_err(|message| structure(format!("invalid {context} path `{path}`: {message}")))?;
    require_text(path, context)
}

pub fn validate_plan_repository_path(path: &str) -> Result<(), &'static str> {
    if path.is_empty() || path.len() > 4_096 || path.starts_with('/') || path.starts_with("//") {
        return Err("absolute and empty paths are forbidden");
    }
    if path.contains('\\') || path.contains(':') {
        return Err("drive, UNC, backslash, and alternate-stream forms are forbidden");
    }
    if path
        .chars()
        .any(|character| character.is_control() || character == '\0')
    {
        return Err("control characters are forbidden");
    }
    if !path.is_ascii() {
        return Err("non-ASCII path aliases are forbidden");
    }
    if path.chars().any(char::is_uppercase) || path.contains(['*', '?', '[', ']']) {
        return Err("ambiguous-case and glob path forms are forbidden");
    }
    for part in path.split('/') {
        if part.is_empty() || matches!(part, "." | "..") || part.contains('~') {
            return Err("empty, dot, dotdot, and home-alias components are forbidden");
        }
        if part.ends_with('.') || part.ends_with(' ') {
            return Err("trailing-dot and trailing-space aliases are forbidden");
        }
        let device = part
            .split_once('.')
            .map_or(part, |(stem, _)| stem)
            .to_ascii_uppercase();
        if matches!(device.as_str(), "CON" | "PRN" | "AUX" | "NUL")
            || device.strip_prefix("COM").is_some_and(|suffix| {
                matches!(suffix, "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9")
            })
            || device.strip_prefix("LPT").is_some_and(|suffix| {
                matches!(suffix, "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9")
            })
        {
            return Err("Windows device aliases are forbidden");
        }
    }
    Ok(())
}

pub(super) fn validate_repository_path(path: &str) -> Result<(), &'static str> {
    validate_plan_repository_path(path)
}

fn require_text(value: &str, context: &str) -> Result<(), PlanError> {
    let lower = value.to_ascii_lowercase();
    if value.trim().is_empty()
        || value.contains('<')
        || value.contains('>')
        || lower.contains("todo")
        || lower.contains("tbd")
        || value.contains("???")
    {
        return Err(structure(format!(
            "{context} is empty or contains placeholder text"
        )));
    }
    Ok(())
}

fn structure(message: impl Into<String>) -> PlanError {
    PlanError::Structure(message.into())
}