loopsmith-core 1.0.0

//! Validation of the four-bundle model.
//!
//! The rules here are the corpus rules made mechanical. The most important one
//! is that every goal carries at least one blocking validation: a goal you
//! cannot check is a goal the loop can never honestly finish.

use crate::config::*;
use std::collections::{BTreeMap, BTreeSet};

#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub enum Severity {
    Warning,
    Error,
}

#[derive(Debug, Clone)]
pub struct Issue {
    pub severity: Severity,
    /// Dotted path into the config, e.g. `goals[2].name`.
    pub field: String,
    pub message: String,
}

impl Issue {
    fn err(field: impl Into<String>, message: impl Into<String>) -> Self {
        Issue {
            severity: Severity::Error,
            field: field.into(),
            message: message.into(),
        }
    }
    fn warn(field: impl Into<String>, message: impl Into<String>) -> Self {
        Issue {
            severity: Severity::Warning,
            field: field.into(),
            message: message.into(),
        }
    }
}

#[derive(Debug, Clone, Default)]
pub struct ValidationReport {
    pub issues: Vec<Issue>,
}

impl ValidationReport {
    pub fn has_errors(&self) -> bool {
        self.issues.iter().any(|i| i.severity == Severity::Error)
    }
    pub fn errors(&self) -> impl Iterator<Item = &Issue> {
        self.issues.iter().filter(|i| i.severity == Severity::Error)
    }
    pub fn warnings(&self) -> impl Iterator<Item = &Issue> {
        self.issues
            .iter()
            .filter(|i| i.severity == Severity::Warning)
    }
    pub fn render(&self) -> String {
        let mut out = String::new();
        for i in &self.issues {
            let tag = match i.severity {
                Severity::Error => "error",
                Severity::Warning => "warn ",
            };
            out.push_str(&format!("  {tag}  {}: {}\n", i.field, i.message));
        }
        out
    }
}

pub fn validate(cfg: &LoopConfig) -> ValidationReport {
    let mut r = ValidationReport::default();

    if cfg.name.trim().is_empty() {
        r.issues.push(Issue::err("name", "must not be empty"));
    }
    if cfg.intent.goals.is_empty() {
        r.issues
            .push(Issue::err("intent.goals", "a loop needs at least one goal"));
    }

    let goal_names: BTreeSet<&str> = cfg.intent.goals.iter().map(|g| g.name.as_str()).collect();
    check_goals(cfg, &goal_names, &mut r);
    check_pre_execution(cfg, &mut r);
    check_validations(cfg, &goal_names, &mut r);
    check_success(cfg, &goal_names, &mut r);
    check_stop_gates(cfg, &mut r);
    check_execution_guidelines(cfg, &mut r);
    check_graph(cfg, &goal_names, &mut r);
    check_providers(cfg, &mut r);
    check_gate_rules(cfg, &mut r);
    check_recovery(cfg, &mut r);
    check_alerts(cfg, &mut r);
    check_containers(cfg, &mut r);
    r
}

/// Section I. A phase graph that cannot be scheduled is a config bug, and it is
/// far cheaper to say so now than to discover it when the first arrow turns out
/// to point at a typo three hours into an unattended run.
fn check_execution_guidelines(cfg: &LoopConfig, r: &mut ValidationReport) {
    let g = &cfg.execution.phases;

    let mut seen = BTreeSet::new();
    for (i, item) in g.items.iter().enumerate() {
        if item.name.trim().is_empty() {
            r.issues
                .push(Issue::err(format!("execution.phases.items[{i}].name"), "must not be empty"));
        }
        if !seen.insert(item.name.as_str()) {
            r.issues.push(Issue::err(
                format!("execution.phases.items[{i}].name"),
                format!("duplicate guideline name `{}`", item.name),
            ));
        }
        if item.guideline.trim().len() < 12 {
            r.issues.push(Issue::warn(
                format!("execution.phases.items[{i}].guideline"),
                "too short to steer a node; say what this phase is for and what it must not do",
            ));
        }
    }

    if !g.dependency.is_empty() && g.items.is_empty() {
        r.issues.push(Issue::err(
            "execution.phases.dependency",
            "orders guidelines that do not exist; `items` is empty",
        ));
        return;
    }

    let edges = match g.edges() {
        Ok(e) => e,
        Err(msg) => {
            r.issues.push(Issue::err("execution.phases.dependency", msg));
            return;
        }
    };
    for (from, to) in &edges {
        for name in [from, to] {
            if !seen.contains(name.as_str()) {
                r.issues.push(Issue::err(
                    "execution.phases.dependency",
                    format!("`{name}` is ordered but is not one of: {}", g.names().join(", ")),
                ));
            }
        }
        if from == to {
            r.issues.push(Issue::err(
                "execution.phases.dependency",
                format!("`{from}` cannot come before itself"),
            ));
        }
    }

    // Cycles are found by trying to schedule. Reusing the scheduler rather than
    // writing a second traversal is the point of the `DagNode` trait.
    if let Ok(phases) = g.phases() {
        if let Err(e) = topo_order(&phases) {
            r.issues.push(Issue::err("execution.phases.dependency", e));
        }
    }

    // A node pointing at a phase that does not exist would simply never run.
    for (i, n) in cfg.execution.graph.nodes.iter().enumerate() {
        if let Some(stage) = &n.stage {
            if !seen.contains(stage.as_str()) {
                r.issues.push(Issue::err(
                    format!("execution.graph.nodes[{i}].stage"),
                    format!(
                        "`{stage}` is not a guideline in `execution_guidelines.items`; \
                         this node would never be dispatched"
                    ),
                ));
            }
        }
    }
}

/// Kahn's algorithm over phase names. `loopsmith-graph` owns the real
/// scheduler, but `loopsmith-core` cannot depend on it (the dependency runs the
/// other way), so cycle detection for validation lives here.
fn topo_order(phases: &[crate::Phase]) -> Result<(), String> {
    use std::collections::BTreeMap;
    let names: BTreeSet<&str> = phases.iter().map(|p| p.name.as_str()).collect();
    let mut indegree: BTreeMap<&str, usize> = names.iter().map(|n| (*n, 0)).collect();
    let mut dependents: BTreeMap<&str, Vec<&str>> = BTreeMap::new();
    for p in phases {
        for d in &p.depends_on {
            if !names.contains(d.as_str()) {
                continue; // already reported as an unknown name
            }
            *indegree.get_mut(p.name.as_str()).unwrap() += 1;
            dependents.entry(d.as_str()).or_default().push(p.name.as_str());
        }
    }
    let mut ready: Vec<&str> = indegree
        .iter()
        .filter(|(_, &d)| d == 0)
        .map(|(n, _)| *n)
        .collect();
    let mut placed = 0usize;
    while let Some(n) = ready.pop() {
        placed += 1;
        for d in dependents.get(n).into_iter().flatten() {
            let e = indegree.get_mut(*d).unwrap();
            *e -= 1;
            if *e == 0 {
                ready.push(d);
            }
        }
    }
    if placed != phases.len() {
        let stuck: Vec<&str> = indegree
            .iter()
            .filter(|(_, &d)| d > 0)
            .map(|(n, _)| *n)
            .collect();
        return Err(format!(
            "these guidelines depend on each other in a cycle: {}",
            stuck.join(", ")
        ));
    }
    Ok(())
}

fn check_goals(cfg: &LoopConfig, names: &BTreeSet<&str>, r: &mut ValidationReport) {
    let mut seen = BTreeSet::new();
    for (i, g) in cfg.intent.goals.iter().enumerate() {
        let f = format!("intent.goals[{i}]");
        if g.name.trim().is_empty() {
            r.issues.push(Issue::err(format!("{f}.name"), "must not be empty"));
        }
        if g.name == OVERALL {
            r.issues.push(Issue::err(
                format!("{f}.name"),
                format!("`{OVERALL}` is reserved for whole-loop targets"),
            ));
        }
        if !seen.insert(g.name.as_str()) {
            r.issues.push(Issue::err(
                format!("{f}.name"),
                format!("duplicate goal name `{}`", g.name),
            ));
        }
        if g.description.trim().len() < 12 {
            r.issues.push(Issue::warn(
                format!("{f}.description"),
                "very short; a vague goal produces a vague verdict",
            ));
        }
        for d in &g.depends_on {
            if !names.contains(d.as_str()) {
                r.issues.push(Issue::err(
                    format!("{f}.depends_on"),
                    format!("unknown goal `{d}`"),
                ));
            }
        }
        if g.depends_on.iter().any(|d| d == &g.name) {
            r.issues
                .push(Issue::err(format!("{f}.depends_on"), "goal depends on itself"));
        }
    }
}

fn check_pre_execution(cfg: &LoopConfig, r: &mut ValidationReport) {
    if cfg.intent.prerequisites.is_empty() {
        r.issues.push(Issue::warn(
            "intent.prerequisites",
            "empty. The corpus rule is to do the task manually first — the manual runs are the spec",
        ));
        return;
    }
    let undone: Vec<&str> = cfg
        .intent
        .prerequisites
        .iter()
        .filter(|w| !w.done)
        .map(|w| w.step.as_str())
        .collect();
    if !undone.is_empty() {
        r.issues.push(Issue::err(
            "intent.prerequisites",
            format!(
                "{} step(s) not marked done: {}. Automating before understanding produces fast, confident garbage",
                undone.len(),
                undone.join("; ")
            ),
        ));
    }
}

/// Artifact names a `regex_match` detector can refer to.
///
/// Evidence is collected from the files this config's own `file_exists`
/// detectors name, registered under both the full path and the stem. A regex
/// naming anything else has nothing to match and fails closed for the whole
/// life of the loop, which reads as "the work is not done" rather than as "this
/// check was never wired up".
fn available_artifacts(cfg: &LoopConfig) -> BTreeSet<String> {
    let mut out = BTreeSet::new();
    for v in &cfg.safety.checks {
        if let Detector::FileExists { path, .. } = &v.detector {
            if let Some(stem) = std::path::Path::new(path)
                .file_stem()
                .and_then(|s| s.to_str())
            {
                out.insert(stem.to_string());
            }
            out.insert(path.clone());
        }
    }
    out
}

fn check_validations(cfg: &LoopConfig, names: &BTreeSet<&str>, r: &mut ValidationReport) {
    let artifacts = available_artifacts(cfg);
    let mut covered: BTreeMap<&str, usize> = BTreeMap::new();
    for (i, v) in cfg.safety.checks.iter().enumerate() {
        let f = format!("safety.checks[{i}]");
        if v.target != OVERALL && !names.contains(v.target.as_str()) {
            r.issues.push(Issue::err(
                format!("{f}.target"),
                format!("unknown target `{}` (expected a goal name or `{OVERALL}`)", v.target),
            ));
        }
        if v.statement.trim().is_empty() {
            r.issues
                .push(Issue::err(format!("{f}.statement"), "must not be empty"));
        }
        match &v.detector {
            Detector::Script { command, .. } if command.trim().is_empty() => {
                r.issues
                    .push(Issue::err(format!("{f}.detector.command"), "must not be empty"));
            }
            Detector::Threshold { metric, .. } if metric.trim().is_empty() => {
                r.issues
                    .push(Issue::err(format!("{f}.detector.metric"), "must not be empty"));
            }
            Detector::RegexMatch { artifact, .. } if !artifacts.contains(artifact) => {
                r.issues.push(Issue::err(
                    format!("{f}.detector.artifact"),
                    format!(
                        "no `file_exists` detector produces `{artifact}`, so this check can \
                         never match. Artifacts are named by the file's stem or its full path; \
                         available here: {}",
                        if artifacts.is_empty() {
                            "none".to_string()
                        } else {
                            artifacts
                                .iter()
                                .cloned()
                                .collect::<Vec<_>>()
                                .join(", ")
                        }
                    ),
                ));
            }
            Detector::Judge { standard, .. } => {
                if standard.trim().is_empty() {
                    r.issues.push(Issue::err(
                        format!("{f}.detector.standard"),
                        "name the external standard the judge checks against; an unnamed standard is an opinion",
                    ));
                }
                if v.blocking && v.mode == Mode::Objective {
                    r.issues.push(Issue::warn(
                        f.clone(),
                        "objective mode with a model judge — prefer a script detector so the verdict is not a model's opinion",
                    ));
                }
            }
            _ => {}
        }
        if v.blocking {
            *covered.entry(v.target.as_str()).or_insert(0) += 1;
        }
    }

    for g in &cfg.intent.goals {
        if covered.get(g.name.as_str()).copied().unwrap_or(0) == 0 {
            r.issues.push(Issue::err(
                format!("safety.checks[target={}]", g.name),
                "goal has no blocking validation; it could never be honestly satisfied",
            ));
        }
    }
    if covered.get(OVERALL).copied().unwrap_or(0) == 0 {
        r.issues.push(Issue::warn(
            format!("safety.checks[target={OVERALL}]"),
            "no overall validation; the loop can only finish per-goal",
        ));
    }
}

fn check_success(cfg: &LoopConfig, names: &BTreeSet<&str>, r: &mut ValidationReport) {
    for (i, s) in cfg.intent.success.iter().enumerate() {
        let f = format!("intent.success[{i}]");
        if s.target != OVERALL && !names.contains(s.target.as_str()) {
            r.issues.push(Issue::err(
                format!("{f}.target"),
                format!("unknown target `{}`", s.target),
            ));
        }
        match (s.mode, s.threshold) {
            (Mode::Percentage, None) => r.issues.push(Issue::err(
                format!("{f}.threshold"),
                "percentage mode requires a threshold between 0.0 and 1.0",
            )),
            (Mode::Percentage, Some(t)) if !(0.0..=1.0).contains(&t) => r.issues.push(Issue::err(
                format!("{f}.threshold"),
                format!("{t} is outside 0.0..=1.0"),
            )),
            _ => {}
        }
    }
}

fn check_stop_gates(cfg: &LoopConfig, r: &mut ValidationReport) {
    let g = &cfg.safety.gates.stop;
    if g.max_iterations == 0 {
        r.issues
            .push(Issue::err("safety.gates.stop.max_iterations", "must be at least 1"));
    }
    if g.max_iterations > 100 {
        r.issues.push(Issue::warn(
            "safety.gates.stop.max_iterations",
            "very high; a loop that cannot converge in 100 iterations usually has a miscalibrated verifier",
        ));
    }
    if g.no_progress_iterations == 0 {
        r.issues.push(Issue::warn(
            "safety.gates.stop.no_progress_iterations",
            "disabled; the loop can spin without changing anything",
        ));
    }
    if let Some(rand_at) = g.no_progress_iterations_randomness {
        let field = "safety.gates.stop.no_progress_iterations_randomness";
        if rand_at == 0 {
            r.issues.push(Issue::err(
                field,
                "must be at least 1; remove it entirely to disable perturbation",
            ));
        } else if g.no_progress_iterations == 0 {
            r.issues.push(Issue::err(
                field,
                "no_progress_iterations is 0, so staleness is never counted and this can never fire",
            ));
        } else if rand_at >= g.no_progress_iterations {
            r.issues.push(Issue::err(
                field,
                format!(
                    "must be less than no_progress_iterations ({}); at {rand_at} the loop halts \
                     before it ever tries something different",
                    g.no_progress_iterations
                ),
            ));
        }
    }
    if g.max_tokens.is_none() && g.max_cost_usd.is_none() && g.max_wall_clock_seconds.is_none() {
        r.issues.push(Issue::warn(
            "safety.gates.stop",
            "no budget ceiling of any kind; an unsolvable task will bill until someone notices",
        ));
    }
}

/// Entry, approval, and rollback rules.
fn check_gate_rules(cfg: &LoopConfig, r: &mut ValidationReport) {
    use crate::{GateKind, GateOutcome};
    let gates = &cfg.safety.gates;
    for (kind, list) in [
        (GateKind::Entry, &gates.entry),
        (GateKind::Approval, &gates.approval),
        (GateKind::Rollback, &gates.rollback),
    ] {
        let mut seen = BTreeSet::new();
        for (i, rule) in list.iter().enumerate() {
            let field = format!("safety.gates.{}[{i}]", kind.as_str());
            if rule.id.trim().is_empty() {
                r.issues.push(Issue::err(format!("{field}.id"), "must not be empty"));
            } else if !seen.insert(rule.id.as_str()) {
                r.issues.push(Issue::err(
                    format!("{field}.id"),
                    format!("`{}` is used twice; the ledger could not tell them apart", rule.id),
                ));
            }
            if kind != GateKind::Rollback && rule.on_fail == GateOutcome::Rollback {
                r.issues.push(Issue::warn(
                    format!("{field}.on_fail"),
                    format!(
                        "an {} rule runs before anything has been done, so there is nothing \
                         to roll back; the run fails instead",
                        kind.as_str()
                    ),
                ));
            }
        }
    }

    // An approval rule nobody checks is a sign-off that never happens. That is
    // a choice a developer may make on their own machine, and one a production
    // loop must not be able to make quietly.
    if !gates.approval.is_empty() && !cfg.features.human_approval {
        let msg = "approval rules are declared but `features.human_approval` is off, so none \
                   of them is checked";
        r.issues.push(if cfg.environment == crate::Environment::Prod {
            Issue::err("features.human_approval", msg)
        } else {
            Issue::warn("features.human_approval", msg)
        });
    }
    if cfg.evolution_enabled() && cfg.evolution.baseline.is_none() {
        r.issues.push(Issue::warn(
            "evolution.baseline",
            "self-evolution is on with no baseline, so no proposal can ever be shown to be an \
             improvement; they are recorded, never adoptable",
        ));
    }
    if cfg.environment == crate::Environment::Prod && !cfg.evolution.require_approval {
        r.issues.push(Issue::err(
            "evolution.require_approval",
            "must stay on in `prod`: a production loop may propose changes to itself, never \
             adopt them unreviewed",
        ));
    }
}

/// Container isolation that has nothing to run in.
fn check_containers(cfg: &LoopConfig, r: &mut ValidationReport) {
    let graph = &cfg.execution.graph;
    for (i, n) in graph.nodes.iter().enumerate() {
        let crate::Isolation::Container { network, .. } = &n.isolation else {
            continue;
        };
        let field = format!("execution.graph.nodes[{i}].isolation");
        if n.isolation.container_image(graph.container_image.as_deref()).is_none() {
            r.issues.push(Issue::warn(
                field.clone(),
                format!(
                    "`{}` asks for a container but no image is named here or in \
                     `execution.graph.container_image`; it will run in a worktree instead",
                    n.id
                ),
            ));
        }
        // A container has no network unless asked for one, and every hosted
        // agent CLI needs one to reach its model. Only a local model can
        // answer from inside a sealed container.
        let hosted = cfg
            .cascade_for(n.tier)
            .iter()
            .chain(n.provider.as_deref().and_then(|id| cfg.provider(id)).iter())
            .any(|p| p.kind != crate::ProviderKind::Ollama);
        if !network && hosted {
            r.issues.push(Issue::warn(
                format!("{field}.network"),
                format!(
                    "`{}` runs in a container with no network, but a provider it can be \
                     routed to is hosted and needs one to reach its model; set `network: true` \
                     or route it to a local model",
                    n.id
                ),
            ));
        }
    }
}

/// Alert thresholds.
fn check_alerts(cfg: &LoopConfig, r: &mut ValidationReport) {
    use crate::Metric;
    let mut seen = BTreeSet::new();
    for (i, a) in cfg.safety.alerts.iter().enumerate() {
        let field = format!("safety.alerts[{i}]");
        if a.id.trim().is_empty() {
            r.issues.push(Issue::err(format!("{field}.id"), "must not be empty"));
        } else if !seen.insert(a.id.as_str()) {
            r.issues.push(Issue::err(
                format!("{field}.id"),
                format!("`{}` is used twice", a.id),
            ));
        }
        match (a.above, a.below) {
            (None, None) => r.issues.push(Issue::err(
                field.clone(),
                "needs `above`, `below`, or both; without one it can never fire",
            )),
            (Some(hi), Some(lo)) if lo >= hi => r.issues.push(Issue::warn(
                field.clone(),
                format!("fires on anything above {hi} or below {lo}, which is every value"),
            )),
            _ => {}
        }
        if a.metric == Metric::ValidationPassRate {
            for t in [a.above, a.below].into_iter().flatten() {
                if !(0.0..=1.0).contains(&t) {
                    r.issues.push(Issue::warn(
                        field.clone(),
                        format!("validation_pass_rate is a fraction from 0 to 1; {t} is outside it"),
                    ));
                }
            }
        }
    }
}

/// The failure-class to action map.
fn check_recovery(cfg: &LoopConfig, r: &mut ValidationReport) {
    use crate::RecoveryAction;
    let rec = &cfg.safety.recovery;
    for class in crate::FailureClass::ALL {
        if let RecoveryAction::Retry { max_attempts, .. } | RecoveryAction::Revise { max_attempts } =
            rec.action_for(class)
        {
            if max_attempts <= 1 {
                r.issues.push(Issue::warn(
                    format!("safety.recovery.{}", class.key()),
                    "max_attempts counts dispatches, so 1 or 0 never tries a second time",
                ));
            }
        }
    }
    if matches!(
        rec.safety_violation,
        RecoveryAction::Retry { .. } | RecoveryAction::Revise { .. } | RecoveryAction::Fallback {}
    ) {
        r.issues.push(Issue::err(
            "safety.recovery.safety_violation",
            "a safety violation cannot be retried, revised, or routed around; use stop, pause, \
             escalate, or restore_checkpoint",
        ));
    }
}

fn check_graph(cfg: &LoopConfig, goal_names: &BTreeSet<&str>, r: &mut ValidationReport) {
    let ids: BTreeSet<&str> = cfg.execution.graph.nodes.iter().map(|n| n.id.as_str()).collect();
    if cfg.execution.graph.nodes.is_empty() {
        r.issues.push(Issue::warn(
            "execution.graph.nodes",
            "no nodes; the loop will run a single implicit builder per goal",
        ));
        return;
    }
    let mut seen = BTreeSet::new();
    let mut has_judge = false;
    for (i, n) in cfg.execution.graph.nodes.iter().enumerate() {
        let f = format!("execution.graph.nodes[{i}]");
        if !seen.insert(n.id.as_str()) {
            r.issues
                .push(Issue::err(format!("{f}.id"), format!("duplicate node id `{}`", n.id)));
        }
        if n.instruction.trim().len() < 16 {
            r.issues.push(Issue::warn(
                format!("{f}.instruction"),
                "thin instruction; vague roles produce whatever the model felt like",
            ));
        }
        if n.weight <= 0.0 {
            r.issues
                .push(Issue::err(format!("{f}.weight"), "must be greater than zero"));
        }
        for d in &n.depends_on {
            if !ids.contains(d.as_str()) {
                r.issues
                    .push(Issue::err(format!("{f}.depends_on"), format!("unknown node `{d}`")));
            }
            if d == &n.id {
                r.issues
                    .push(Issue::err(format!("{f}.depends_on"), "node depends on itself"));
            }
        }
        for g in &n.goals {
            if !goal_names.contains(g.as_str()) {
                r.issues
                    .push(Issue::err(format!("{f}.goals"), format!("unknown goal `{g}`")));
            }
        }
        if let Some(p) = &n.provider {
            if cfg.provider(p).is_none() {
                r.issues.push(Issue::err(
                    format!("{f}.provider"),
                    format!("unknown provider `{p}`"),
                ));
            }
        }
        if n.role == Role::Judge {
            has_judge = true;
        }
    }
    if !has_judge {
        r.issues.push(Issue::warn(
            "execution.graph.nodes",
            "no judge node; verification will fall back to detectors only",
        ));
    }
    if let Concurrency::Fixed { max_parallel } = cfg.execution.graph.concurrency {
        if max_parallel == 0 {
            r.issues.push(Issue::err(
                "execution.graph.concurrency.max_parallel",
                "must be at least 1",
            ));
        }
    }
    // Parallel writers without isolation clobber each other — but only the ones
    // that can actually overlap. Two unisolated builders in a dependency chain
    // never run at the same time, and warning about them trains the reader to
    // ignore the warning that matters.
    let parallel_possible = !matches!(cfg.execution.graph.concurrency, Concurrency::Sequential {});
    if parallel_possible {
        let levels = wave_levels(&cfg.execution.graph.nodes);
        let mut by_wave: BTreeMap<usize, Vec<&str>> = BTreeMap::new();
        for n in cfg
            .execution
            .graph
            .nodes
            .iter()
            .filter(|n| !n.isolation.needs_worktree() && matches!(n.role, Role::Builder))
        {
            let wave = levels.get(n.id.as_str()).copied().unwrap_or(0);
            by_wave.entry(wave).or_default().push(n.id.as_str());
        }
        for (wave, ids) in by_wave.iter().filter(|(_, ids)| ids.len() > 1) {
            r.issues.push(Issue::warn(
                "execution.graph.nodes[].isolation",
                format!(
                    "{} builder nodes run together in wave {} without worktree isolation: {}",
                    ids.len(),
                    wave + 1,
                    ids.join(", ")
                ),
            ));
        }
    }
}

/// Which wave each node lands in: the longest dependency chain ending at it.
///
/// Nodes sharing a wave have no path between them, so they are exactly the ones
/// that can be dispatched at the same time. `loopsmith-graph` computes the same
/// thing with Kahn's algorithm, but the dependency runs the other way — core
/// cannot reach it — so this is a small relaxation pass instead.
fn wave_levels(nodes: &[NodeSpec]) -> BTreeMap<&str, usize> {
    let ids: BTreeSet<&str> = nodes.iter().map(|n| n.id.as_str()).collect();
    let mut level: BTreeMap<&str, usize> = nodes.iter().map(|n| (n.id.as_str(), 0)).collect();

    // The node count bounds the longest possible chain. A cyclic graph stops
    // improving rather than looping forever; cycles are reported at plan time.
    for _ in 0..nodes.len() {
        let mut changed = false;
        for n in nodes {
            let want = n
                .depends_on
                .iter()
                .filter(|d| ids.contains(d.as_str()))
                .map(|d| level.get(d.as_str()).copied().unwrap_or(0) + 1)
                .max()
                .unwrap_or(0);
            if want > level.get(n.id.as_str()).copied().unwrap_or(0) {
                level.insert(n.id.as_str(), want);
                changed = true;
            }
        }
        if !changed {
            break;
        }
    }
    level
}

fn check_providers(cfg: &LoopConfig, r: &mut ValidationReport) {
    if cfg.execution.providers.providers.is_empty() {
        r.issues.push(Issue::warn(
            "execution.providers.providers",
            "none declared; nodes cannot be dispatched until at least one exists",
        ));
        return;
    }
    let mut seen = BTreeSet::new();
    for (i, p) in cfg.execution.providers.providers.iter().enumerate() {
        let f = format!("execution.providers.providers[{i}]");
        if !seen.insert(p.id.as_str()) {
            r.issues
                .push(Issue::err(format!("{f}.id"), format!("duplicate provider id `{}`", p.id)));
        }
        if p.command.trim().is_empty() {
            r.issues
                .push(Issue::err(format!("{f}.command"), "must not be empty"));
        }
    }
    for (tier, ids) in &cfg.execution.providers.cascade {
        if !matches!(tier.as_str(), "cheap" | "standard" | "strong") {
            r.issues.push(Issue::err(
                format!("execution.providers.cascade.{tier}"),
                "tier must be one of cheap, standard, strong",
            ));
        }
        for id in ids {
            if cfg.provider(id).is_none() {
                r.issues.push(Issue::err(
                    format!("execution.providers.cascade.{tier}"),
                    format!("unknown provider `{id}`"),
                ));
            }
        }
    }
    if cfg.execution.providers.enforce_judge_independence {
        let distinct: BTreeSet<&str> = cfg
            .execution
            .providers
            .providers
            .iter()
            .map(|p| p.id.as_str())
            .collect();
        if distinct.len() < 2 {
            r.issues.push(Issue::warn(
                "execution.providers",
                "judge independence is enforced but only one provider exists; judges will fall back to detector-only verdicts",
            ));
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    fn minimal() -> LoopConfig {
        crate::parse_str(
            r#"
name: t
goals:
  - name: g1
    description: a sufficiently long goal description
validations:
  - target: g1
    name: v1
    mode: objective
    statement: tests pass
    detector: { type: script, command: "true" }
pre_execution:
  - step: ran it by hand
    done: true
"#,
            "test",
        )
        .expect("parses")
    }

    /// Every issue names a path the 1.0 config actually has.
    ///
    /// An issue's `field` is not decoration: the web UI routes it to the step
    /// that owns it and scrolls to the card that edits it, and `help.rs` keys
    /// its notes by the same string. A leftover 0.3 spelling — `stop_gates`
    /// rather than `safety.gates.stop` — still reads fine in the terminal and
    /// silently breaks both, which is why this walks the whole surface rather
    /// than trusting the rename.
    #[test]
    fn every_issue_names_a_path_the_config_has() {
        const ROOTS: [&str; 9] = [
            "name", "version", "description", "environment", "intent", "execution", "safety",
            "evolution", "features",
        ];

        // Trip as many checks as one config can: a goal nothing blocks, a
        // dangling cascade entry, one provider with independence on, a graph
        // whose parallel builders share a tree, a stage nothing declares, and
        // no budget ceiling anywhere.
        let bad: LoopConfig = crate::parse_str(
            r#"
name: t
intent:
  goals:
    - name: g1
      description: a sufficiently long goal description
    - name: g2
      description: another sufficiently long goal description
safety:
  checks:
    - target: g1
      name: v1
      mode: objective
      statement: tests pass
      detector: { type: regex_match, artifact: nobody-writes-this.txt, pattern: ok }
      blocking: false
  gates:
    entry:
      - id: dup
        statement: s
        detector: { type: file_exists, path: x }
      - id: dup
        statement: s
        detector: { type: file_exists, path: x }
execution:
  providers:
    providers:
      - id: only
        kind: custom
        command: "true"
    cascade:
      cheap: [nobody]
  phases:
    dependency: ["a -> b"]
  graph:
    nodes:
      - id: n1
        role: builder
        instruction: do the thing
        stage: nowhere
      - id: n2
        role: builder
        instruction: do the other thing
"#,
            "test",
        )
        .expect("parses");

        let report = validate(&bad);
        assert!(
            report.issues.len() >= 6,
            "this config was meant to trip most of the validator: {:?}",
            report.issues
        );
        for issue in &report.issues {
            let root = issue
                .field
                .split(['.', '['])
                .next()
                .unwrap_or(issue.field.as_str());
            assert!(
                ROOTS.contains(&root),
                "`{}` is not a 1.0 config path ({})",
                issue.field,
                issue.message
            );
        }
    }

    fn errors_on(cfg: &LoopConfig, field: &str) -> usize {
        validate(cfg).errors().filter(|i| i.field == field).count()
    }

    fn warnings_on(cfg: &LoopConfig, field: &str) -> usize {
        validate(cfg).warnings().filter(|i| i.field == field).count()
    }

    fn rule(id: &str, on_fail: &str) -> crate::GateRule {
        serde_yaml::from_str(&format!(
            "id: {id}\nstatement: s\ndetector: {{ type: file_exists, path: x }}\non_fail: {on_fail}\n"
        ))
        .unwrap()
    }

    #[test]
    fn a_rule_id_used_twice_is_refused() {
        let mut c = minimal();
        c.safety.gates.entry = vec![rule("a", "stop"), rule("a", "pause")];
        assert_eq!(errors_on(&c, "safety.gates.entry[1].id"), 1);
    }

    #[test]
    fn an_entry_rule_cannot_roll_back_what_has_not_run() {
        let mut c = minimal();
        c.safety.gates.entry = vec![rule("a", "rollback")];
        assert_eq!(warnings_on(&c, "safety.gates.entry[0].on_fail"), 1);
        c.safety.gates.rollback = vec![rule("b", "rollback")];
        assert_eq!(warnings_on(&c, "safety.gates.rollback[0].on_fail"), 0);
    }

    #[test]
    fn unchecked_approval_rules_are_refused_in_prod_and_warned_about_elsewhere() {
        let mut c = minimal();
        c.safety.gates.approval = vec![rule("signed-off", "pause")];
        c.features.human_approval = false;
        assert_eq!(warnings_on(&c, "features.human_approval"), 1);
        c.environment = crate::Environment::Prod;
        assert_eq!(errors_on(&c, "features.human_approval"), 1);
    }

    #[test]
    fn evolution_without_a_baseline_is_warned_about() {
        let mut c = minimal();
        c.features.self_evolution = true;
        c.evolution.enabled = true;
        assert_eq!(warnings_on(&c, "evolution.baseline"), 1);
        c.evolution.baseline = Some(Default::default());
        assert_eq!(warnings_on(&c, "evolution.baseline"), 0);
    }

    #[test]
    fn an_alert_that_can_never_fire_is_refused() {
        let mut c = minimal();
        c.safety.alerts = serde_yaml::from_str("- id: a\n  metric: cost_usd\n").unwrap();
        assert_eq!(errors_on(&c, "safety.alerts[0]"), 1);
    }

    #[test]
    fn a_sealed_container_in_front_of_a_hosted_model_is_warned_about() {
        let mut c = minimal();
        c.execution.providers.providers = serde_yaml::from_str(
            "- id: hosted\n  kind: claude_code\n  command: claude\n",
        )
        .unwrap();
        c.execution.graph.container_image = Some("img".into());
        c.execution.graph.nodes = serde_yaml::from_str(
            "- id: b\n  role: builder\n  instruction: do the thing well\n  \
             isolation: { mode: container }\n",
        )
        .unwrap();
        assert_eq!(warnings_on(&c, "execution.graph.nodes[0].isolation.network"), 1);
        c.execution.graph.nodes[0].isolation = crate::Isolation::Container {
            image: None,
            network: true,
        };
        assert_eq!(warnings_on(&c, "execution.graph.nodes[0].isolation.network"), 0);
    }

    #[test]
    fn a_safety_violation_cannot_be_retried() {
        let mut c = minimal();
        c.safety.recovery.safety_violation = crate::RecoveryAction::Retry {
            max_attempts: 3,
            base_delay_seconds: 1,
            backoff: crate::Backoff::Fixed,
        };
        assert_eq!(errors_on(&c, "safety.recovery.safety_violation"), 1);
    }

    #[test]
    fn the_default_policy_raises_nothing() {
        // The shipped examples use every default, and CI asserts they raise
        // exactly one issue. None of these checks may be it.
        let c = minimal();
        let report = validate(&c);
        assert!(
            report
                .issues
                .iter()
                .all(|i| !i.field.starts_with("safety.gates.entry")
                    && !i.field.starts_with("safety.recovery")
                    && i.field != "features.human_approval"),
            "{:?}",
            report.issues
        );
    }

    #[test]
    fn minimal_config_is_valid() {
        let r = validate(&minimal());
        assert!(!r.has_errors(), "unexpected errors:\n{}", r.render());
    }

    #[test]
    fn a_regex_naming_an_artifact_nobody_produces_is_an_error() {
        // Evidence is collected from the files `file_exists` detectors name.
        // A regex naming anything else has nothing to match and fails closed
        // for the life of the loop, which reads as "the work is not done"
        // rather than as "this check was never wired up".
        let mut c = minimal();
        c.safety.checks.push(crate::Validation {
            target: "g1".into(),
            name: "cited".into(),
            mode: Mode::Objective,
            statement: "the notes carry source URLs".into(),
            detector: Detector::RegexMatch {
                artifact: "notes".into(),
                pattern: "https?://".into(),
            },
            blocking: true,
        });
        let r = validate(&c);
        assert!(r.has_errors(), "{}", r.render());
        assert!(
            r.render().contains("can never match"),
            "the error must say why: {}",
            r.render()
        );
    }

    #[test]
    fn a_regex_over_a_file_the_config_declares_is_accepted() {
        let mut c = minimal();
        c.safety.checks.push(crate::Validation {
            target: "g1".into(),
            name: "notes-exist".into(),
            mode: Mode::Objective,
            statement: "the notes exist".into(),
            detector: Detector::FileExists {
                path: "out/notes.md".into(),
                non_empty: true,
            },
            blocking: true,
        });
        // Both spellings resolve: the file's stem and its full path.
        for artifact in ["notes", "out/notes.md"] {
            let mut c = c.clone();
            c.safety.checks.push(crate::Validation {
                target: "g1".into(),
                name: "cited".into(),
                mode: Mode::Objective,
                statement: "the notes carry source URLs".into(),
                detector: Detector::RegexMatch {
                    artifact: artifact.into(),
                    pattern: "https?://".into(),
                },
                blocking: true,
            });
            let r = validate(&c);
            assert!(!r.has_errors(), "`{artifact}` should resolve:\n{}", r.render());
        }
    }

    #[test]
    fn goal_without_blocking_validation_is_an_error() {
        let mut c = minimal();
        c.safety.checks[0].blocking = false;
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("no blocking validation"));
    }

    fn builder(id: &str, deps: &[&str]) -> NodeSpec {
        NodeSpec {
            id: id.into(),
            role: Role::Builder,
            instruction: "produce the thing described in the goal".into(),
            depends_on: deps.iter().map(|s| s.to_string()).collect(),
            goals: vec![],
            tier: Tier::Standard,
            provider: None,
            stage: None,
            skills: vec![],
            weight: 1.0,
            isolation: Isolation::None {},
        }
    }

    #[test]
    fn chained_builders_are_not_reported_as_parallel_writers() {
        // `make-media -> publish` cannot overlap, so warning about it trains the
        // reader to ignore the warning that matters.
        let mut c = minimal();
        c.execution.graph.nodes = vec![
            builder("draft", &[]),
            builder("make-media", &["draft"]),
            builder("publish", &["make-media"]),
        ];
        c.execution.graph.concurrency = Concurrency::Auto {
            cap: 4,
            min_marginal_gain: 0.05,
        };
        assert!(
            !validate(&c).render().contains("without worktree isolation"),
            "a straight chain has no parallel writers:\n{}",
            validate(&c).render()
        );
    }

    #[test]
    fn builders_that_really_can_overlap_are_still_reported() {
        let mut c = minimal();
        c.execution.graph.nodes = vec![
            builder("survey", &[]),
            builder("refactor-a", &["survey"]),
            builder("refactor-b", &["survey"]),
        ];
        c.execution.graph.concurrency = Concurrency::Auto {
            cap: 4,
            min_marginal_gain: 0.05,
        };
        let report = validate(&c).render();
        assert!(report.contains("run together in wave 2"), "got:\n{report}");
        assert!(report.contains("refactor-a, refactor-b"), "got:\n{report}");
        assert!(
            !report.contains("survey,"),
            "the node they both depend on is not one of them:\n{report}"
        );
    }

    #[test]
    fn sequential_concurrency_silences_the_warning_entirely() {
        let mut c = minimal();
        c.execution.graph.nodes = vec![builder("a", &[]), builder("b", &[])];
        c.execution.graph.concurrency = Concurrency::Sequential {};
        assert!(!validate(&c).render().contains("without worktree isolation"));
    }

    #[test]
    fn wave_levels_follow_the_longest_chain() {
        // `d` depends on both a one-hop and a two-hop path; the longest wins,
        // which is what decides whether two nodes can share a wave.
        let nodes = vec![
            builder("a", &[]),
            builder("b", &["a"]),
            builder("c", &["b"]),
            builder("d", &["a", "c"]),
        ];
        let levels = wave_levels(&nodes);
        assert_eq!(levels["a"], 0);
        assert_eq!(levels["b"], 1);
        assert_eq!(levels["c"], 2);
        assert_eq!(levels["d"], 3);
    }

    #[test]
    fn a_cycle_does_not_hang_the_wave_computation() {
        // Cycles are reported at plan time; this must terminate, not loop.
        let nodes = vec![builder("a", &["b"]), builder("b", &["a"])];
        let levels = wave_levels(&nodes);
        assert_eq!(levels.len(), 2);
    }

    #[test]
    fn a_randomness_threshold_at_or_past_the_halt_point_is_refused() {
        // At or past `no_progress_iterations` the loop halts first, so the
        // perturbation would never fire and the author would never find out.
        let mut c = minimal();
        c.safety.gates.stop.no_progress_iterations = 3;
        for at in [3u32, 4] {
            c.safety.gates.stop.no_progress_iterations_randomness = Some(at);
            let r = validate(&c);
            assert!(r.has_errors(), "{at} should be refused against a halt of 3");
            assert!(r.render().contains("must be less than no_progress_iterations"));
        }

        c.safety.gates.stop.no_progress_iterations_randomness = Some(2);
        assert!(
            !validate(&c)
                .render()
                .contains("no_progress_iterations_randomness"),
            "2 is below the halt point and should be accepted"
        );
    }

    #[test]
    fn randomness_is_refused_when_staleness_is_never_counted() {
        let mut c = minimal();
        c.safety.gates.stop.no_progress_iterations = 0;
        c.safety.gates.stop.no_progress_iterations_randomness = Some(1);
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("staleness is never counted"));
    }

    #[test]
    fn an_execution_guideline_cycle_is_refused() {
        let mut c = minimal();
        c.execution.phases = ExecutionGuidelines {
            items: vec![
                Guideline {
                    name: "a".into(),
                    guideline: "the first phase of a cycle".into(),
                    note: None,
                },
                Guideline {
                    name: "b".into(),
                    guideline: "the second phase of a cycle".into(),
                    note: None,
                },
            ],
            dependency: vec!["a -> b".into(), "b -> a".into()],
        };
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("cycle"));
    }

    #[test]
    fn an_unknown_guideline_name_in_an_arrow_is_refused() {
        let mut c = minimal();
        c.execution.phases = ExecutionGuidelines {
            items: vec![Guideline {
                name: "gather".into(),
                guideline: "collect the sources first".into(),
                note: None,
            }],
            dependency: vec!["gather -> drfat".into()],
        };
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("drfat"));
    }

    #[test]
    fn undone_pre_execution_blocks_the_run() {
        let mut c = minimal();
        c.intent.prerequisites[0].done = false;
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("not marked done"));
    }

    #[test]
    fn overall_is_reserved_as_a_goal_name() {
        let mut c = minimal();
        c.intent.goals[0].name = OVERALL.into();
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("reserved"));
    }

    #[test]
    fn unknown_validation_target_is_an_error() {
        let mut c = minimal();
        c.safety.checks[0].target = "nope".into();
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("unknown target"));
    }

    #[test]
    fn judge_detector_requires_a_named_standard() {
        let mut c = minimal();
        c.safety.checks[0].detector = Detector::Judge {
            standard: "  ".into(),
            min_score: None,
        };
        let r = validate(&c);
        assert!(r.has_errors());
        assert!(r.render().contains("name the external standard"));
    }

    #[test]
    fn constraint_merge_appends_rules_and_overrides_limits() {
        let g = ConstraintSet {
            rules: vec!["a".into()],
            max_tokens: Some(10),
            ..Default::default()
        };
        let n = ConstraintSet {
            rules: vec!["b".into()],
            max_tokens: Some(20),
            ..Default::default()
        };
        let m = ConstraintSet::merged(&g, Some(&n));
        assert_eq!(m.rules, vec!["a".to_string(), "b".to_string()]);
        assert_eq!(m.max_tokens, Some(20));
    }
}