daedalus-planner 0.1.1

use daedalus_data::convert::{ConversionProvenance, ConversionResolution, ConverterId};
use daedalus_data::model::{TypeExpr, Value, ValueType};
use daedalus_registry::ids::NodeId;
use daedalus_registry::store::NodeDescriptor;
use std::collections::{BTreeMap, BTreeSet, HashMap, HashSet};

use crate::diagnostics::{Diagnostic, DiagnosticCode};
use crate::graph::NodeInstance;
use crate::graph::{ComputeAffinity, Edge, ExecutionPlan, Graph, NodeRef, PortRef};

const DYNAMIC_INPUT_TYPES_KEY: &str = "dynamic_input_types";
const DYNAMIC_OUTPUT_TYPES_KEY: &str = "dynamic_output_types";
const EMBEDDED_GRAPH_KEY: &str = "daedalus.embedded_graph";
const EMBEDDED_HOST_KEY: &str = "daedalus.embedded_host";
const EMBEDDED_GROUP_KEY: &str = "daedalus.embedded_group";

/// Static planner config controlling optional passes.
///
/// ```
/// use daedalus_planner::PlannerConfig;
/// let cfg = PlannerConfig::default();
/// assert!(!cfg.enable_gpu);
/// ```
#[derive(Clone, Debug, Default)]
pub struct PlannerConfig {
    pub enable_gpu: bool,
    pub enable_lints: bool,
    pub active_features: Vec<String>,
    #[cfg(feature = "gpu")]
    pub gpu_caps: Option<daedalus_gpu::GpuCapabilities>,
}

/// Input to the planner: a graph plus registry reference.
///
/// ```
/// use daedalus_planner::{PlannerInput, Graph};
/// use daedalus_registry::store::Registry;
/// let registry = Registry::new();
/// let input = PlannerInput { graph: Graph::default(), registry: &registry };
/// assert_eq!(input.graph.nodes.len(), 0);
/// ```
#[derive(Clone, Debug)]
pub struct PlannerInput<'a> {
    pub graph: Graph,
    pub registry: &'a daedalus_registry::store::Registry,
}

/// Planner output: final plan and any diagnostics.
///
/// ```
/// use daedalus_planner::{PlannerOutput, ExecutionPlan, Graph};
/// let out = PlannerOutput { plan: ExecutionPlan::new(Graph::default(), vec![]), diagnostics: vec![] };
/// assert!(out.diagnostics.is_empty());
/// ```
#[derive(Clone, Debug)]
pub struct PlannerOutput {
    pub plan: ExecutionPlan,
    pub diagnostics: Vec<Diagnostic>,
}

fn is_host_bridge(node: &NodeInstance) -> bool {
    matches!(
        node.metadata.get("host_bridge"),
        Some(daedalus_data::model::Value::Bool(true))
    )
}

fn diagnostic_node_id(node: &NodeInstance) -> String {
    const UI_NODE_ID_KEY: &str = "helios.ui.node_id";
    if let Some(daedalus_data::model::Value::String(value)) = node.metadata.get(UI_NODE_ID_KEY) {
        let trimmed = value.trim();
        if !trimmed.is_empty() {
            return trimmed.to_string();
        }
    }
    if let Some(label) = node.label.as_deref() {
        let trimmed = label.trim();
        if !trimmed.is_empty() {
            return trimmed.to_string();
        }
    }
    node.id.0.clone()
}

fn expand_embedded_graphs(
    input: &mut PlannerInput<'_>,
    view: &daedalus_registry::store::RegistryView,
    diags: &mut Vec<Diagnostic>,
) {
    let mut embedded_graphs: HashMap<usize, Graph> = HashMap::new();
    for (idx, node) in input.graph.nodes.iter().enumerate() {
        let Some(desc) = latest_node(view, &node.id) else {
            continue;
        };
        let Some(Value::String(raw)) = desc.metadata.get(EMBEDDED_GRAPH_KEY) else {
            continue;
        };
        let parsed: Result<Graph, _> = serde_json::from_str(raw.as_ref());
        match parsed {
            Ok(graph) => {
                embedded_graphs.insert(idx, graph);
            }
            Err(err) => {
                diags.push(
                    Diagnostic::new(
                        DiagnosticCode::NodeMissing,
                        format!("embedded graph parse failed: {err}"),
                    )
                    .in_pass("expand_embedded")
                    .at_node(diagnostic_node_id(node)),
                );
            }
        }
    }

    if embedded_graphs.is_empty() {
        return;
    }

    let mut connected_inputs: HashMap<usize, HashSet<String>> = HashMap::new();
    for edge in &input.graph.edges {
        if embedded_graphs.contains_key(&edge.to.node.0) {
            connected_inputs
                .entry(edge.to.node.0)
                .or_default()
                .insert(edge.to.port.clone());
        }
    }

    #[derive(Clone, Debug)]
    struct EmbeddedMap {
        inputs: BTreeMap<String, Vec<PortRef>>,
        outputs: BTreeMap<String, Vec<PortRef>>,
    }

    let mut new_nodes: Vec<NodeInstance> = Vec::new();
    let mut embedded_internal_edges: Vec<Edge> = Vec::new();
    let mut remap: Vec<Option<usize>> = vec![None; input.graph.nodes.len()];
    let mut embedded_maps: HashMap<usize, EmbeddedMap> = HashMap::new();

    for (idx, node) in input.graph.nodes.iter().enumerate() {
        let Some(graph) = embedded_graphs.get(&idx) else {
            let new_idx = new_nodes.len();
            new_nodes.push(node.clone());
            remap[idx] = Some(new_idx);
            continue;
        };

        let host_index = graph.nodes.iter().position(is_host_bridge).or_else(|| {
            let host_label = latest_node(view, &node.id)
                .and_then(|desc| desc.metadata.get(EMBEDDED_HOST_KEY))
                .and_then(|val| match val {
                    Value::String(s) => {
                        let trimmed = s.trim();
                        if trimmed.is_empty() {
                            None
                        } else {
                            Some(trimmed.to_string())
                        }
                    }
                    _ => None,
                });
            host_label.and_then(|label| {
                graph
                    .nodes
                    .iter()
                    .position(|n| n.label.as_deref() == Some(label.as_str()))
            })
        });

        let Some(host_index) = host_index else {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::NodeMissing,
                    "embedded graph missing host bridge".to_string(),
                )
                .in_pass("expand_embedded")
                .at_node(diagnostic_node_id(node)),
            );
            let new_idx = new_nodes.len();
            new_nodes.push(node.clone());
            remap[idx] = Some(new_idx);
            continue;
        };

        let group_label = node
            .label
            .clone()
            .unwrap_or_else(|| node.id.0.clone());
        let prefix = format!("{group_label}::");
        let mut index_map: Vec<Option<usize>> = vec![None; graph.nodes.len()];

        for (g_idx, g_node) in graph.nodes.iter().enumerate() {
            if g_idx == host_index {
                continue;
            }
            let mut cloned = g_node.clone();
            let base_label = cloned
                .label
                .clone()
                .unwrap_or_else(|| cloned.id.0.clone());
            cloned.label = Some(format!("{prefix}{base_label}"));
            cloned.metadata.insert(
                EMBEDDED_GROUP_KEY.to_string(),
                Value::String(std::borrow::Cow::from(group_label.clone())),
            );
            let new_idx = new_nodes.len();
            new_nodes.push(cloned);
            index_map[g_idx] = Some(new_idx);
        }

        let mut inputs: BTreeMap<String, Vec<PortRef>> = BTreeMap::new();
        let mut outputs: BTreeMap<String, Vec<PortRef>> = BTreeMap::new();

        for edge in &graph.edges {
            let from_is_host = edge.from.node.0 == host_index;
            let to_is_host = edge.to.node.0 == host_index;

            match (from_is_host, to_is_host) {
                (true, false) => {
                    if let Some(target_idx) = index_map[edge.to.node.0] {
                        inputs
                            .entry(edge.from.port.clone())
                            .or_default()
                            .push(PortRef {
                                node: NodeRef(target_idx),
                                port: edge.to.port.clone(),
                            });
                    }
                }
                (false, true) => {
                    if let Some(source_idx) = index_map[edge.from.node.0] {
                        outputs
                            .entry(edge.to.port.clone())
                            .or_default()
                            .push(PortRef {
                                node: NodeRef(source_idx),
                                port: edge.from.port.clone(),
                            });
                    }
                }
                (false, false) => {
                    let Some(from_idx) = index_map[edge.from.node.0] else {
                        continue;
                    };
                    let Some(to_idx) = index_map[edge.to.node.0] else {
                        continue;
                    };
                    embedded_internal_edges.push(Edge {
                        from: PortRef {
                            node: NodeRef(from_idx),
                            port: edge.from.port.clone(),
                        },
                        to: PortRef {
                            node: NodeRef(to_idx),
                            port: edge.to.port.clone(),
                        },
                        metadata: edge.metadata.clone(),
                    });
                }
                (true, true) => {}
            }
        }

        embedded_maps.insert(
            idx,
            EmbeddedMap {
                inputs,
                outputs,
            },
        );
    }

    let mut new_edges: Vec<Edge> = Vec::new();
    for edge in &input.graph.edges {
        let from_map = embedded_maps.get(&edge.from.node.0);
        let to_map = embedded_maps.get(&edge.to.node.0);

        match (from_map, to_map) {
            (None, None) => {
                let Some(from_idx) = remap[edge.from.node.0] else {
                    continue;
                };
                let Some(to_idx) = remap[edge.to.node.0] else {
                    continue;
                };
                new_edges.push(Edge {
                    from: PortRef {
                        node: NodeRef(from_idx),
                        port: edge.from.port.clone(),
                    },
                    to: PortRef {
                        node: NodeRef(to_idx),
                        port: edge.to.port.clone(),
                    },
                    metadata: edge.metadata.clone(),
                });
            }
            (None, Some(to)) => {
                let Some(from_idx) = remap[edge.from.node.0] else {
                    continue;
                };
                if let Some(targets) = to.inputs.get(&edge.to.port) {
                    for target in targets {
                        new_edges.push(Edge {
                            from: PortRef {
                                node: NodeRef(from_idx),
                                port: edge.from.port.clone(),
                            },
                            to: target.clone(),
                            metadata: edge.metadata.clone(),
                        });
                    }
                }
            }
            (Some(from), None) => {
                let Some(to_idx) = remap[edge.to.node.0] else {
                    continue;
                };
                if let Some(sources) = from.outputs.get(&edge.from.port) {
                    for source in sources {
                        new_edges.push(Edge {
                            from: source.clone(),
                            to: PortRef {
                                node: NodeRef(to_idx),
                                port: edge.to.port.clone(),
                            },
                            metadata: edge.metadata.clone(),
                        });
                    }
                }
            }
            (Some(from), Some(to)) => {
                let sources = from.outputs.get(&edge.from.port);
                let targets = to.inputs.get(&edge.to.port);
                if let (Some(sources), Some(targets)) = (sources, targets) {
                    for source in sources {
                        for target in targets {
                            new_edges.push(Edge {
                                from: source.clone(),
                                to: target.clone(),
                                metadata: edge.metadata.clone(),
                            });
                        }
                    }
                }
            }
        }
    }

    // Apply const inputs from embedded nodes when there is no incoming edge.
    for (idx, node) in input.graph.nodes.iter().enumerate() {
        let Some(map) = embedded_maps.get(&idx) else {
            continue;
        };
        let connected = connected_inputs.get(&idx);
        for (port, value) in &node.const_inputs {
            if connected
                .map(|set| set.contains(port))
                .unwrap_or(false)
            {
                continue;
            }
            if let Some(targets) = map.inputs.get(port) {
                for target in targets {
                    if let Some(inner) = new_nodes.get_mut(target.node.0) {
                        inner.const_inputs.retain(|(name, _)| name != &target.port);
                        inner.const_inputs.push((target.port.clone(), value.clone()));
                    }
                }
            }
        }
    }

    new_edges.extend(embedded_internal_edges);

    input.graph.nodes = new_nodes;
    input.graph.edges = new_edges;
}

fn apply_descriptor_defaults(graph: &mut Graph, view: &daedalus_registry::store::RegistryView) {
    for node in &mut graph.nodes {
        let Some(desc) = latest_node(view, &node.id) else {
            continue;
        };
        for port in &desc.inputs {
            let Some(value) = &port.const_value else {
                continue;
            };
            if node.const_inputs.iter().any(|(name, _)| name == &port.name) {
                continue;
            }
            node.const_inputs.push((port.name.clone(), value.clone()));
        }
    }
}

/// Build an execution plan by running the ordered pass pipeline.
/// Currently stubs; contracts are enforced via deterministic diagnostics ordering.
/// Build an execution plan from a graph and registry.
///
/// ```
/// use daedalus_planner::{build_plan, PlannerConfig, PlannerInput, Graph};
/// use daedalus_registry::store::Registry;
/// let registry = Registry::new();
/// let out = build_plan(PlannerInput { graph: Graph::default(), registry: &registry }, PlannerConfig::default());
/// assert_eq!(out.plan.graph.nodes.len(), 0);
/// ```
pub fn build_plan(mut input: PlannerInput<'_>, config: PlannerConfig) -> PlannerOutput {
    let mut diags = Vec::new();
    let view = input.registry.view();

    // Security/integrity: clients can attach arbitrary node metadata in Graph JSON. These keys are
    // planner-owned and must not be accepted as inputs, otherwise a client can "force" types.
    for node in &mut input.graph.nodes {
        node.metadata.remove(DYNAMIC_INPUT_TYPES_KEY);
        node.metadata.remove(DYNAMIC_OUTPUT_TYPES_KEY);
        node.metadata.remove("dynamic_inputs");
        node.metadata.remove("dynamic_outputs");
    }

    // Placeholder passes; extend with real logic per PLAN.md.
    expand_embedded_graphs(&mut input, &view, &mut diags);
    apply_descriptor_defaults(&mut input.graph, &view);
    hydrate_registry(&input, &view, &mut diags);
    typecheck(&mut input.graph, &view, &mut diags);
    convert(&mut input.graph, input.registry, &view, &mut diags, &config);
    align(&mut input.graph, &mut diags);
    gpu(&mut input.graph, &config, &mut diags);
    schedule(&mut input.graph, &mut diags);
    if config.enable_lints {
        lint(&input, &mut diags);
    }

    let plan = ExecutionPlan::new(input.graph.clone(), diags.clone());
    PlannerOutput {
        plan,
        diagnostics: diags,
    }
}

fn latest_node<'a>(
    view: &'a daedalus_registry::store::RegistryView,
    id: &NodeId,
) -> Option<&'a NodeDescriptor> {
    view.nodes.get(id)
}

fn hydrate_registry(
    input: &PlannerInput<'_>,
    view: &daedalus_registry::store::RegistryView,
    diags: &mut Vec<Diagnostic>,
) {
    for node in &input.graph.nodes {
        if latest_node(view, &node.id).is_none() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::NodeMissing,
                    format!("node {} not found in registry", node.id.0),
                )
                .in_pass("hydrate_registry")
                .at_node(diagnostic_node_id(node)),
            );
        }
    }
}

fn typecheck(
    graph: &mut Graph,
    view: &daedalus_registry::store::RegistryView,
    diags: &mut Vec<Diagnostic>,
) {
    #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
    struct TypeVarKey {
        node: usize,
        is_input: bool,
        port: String,
    }

    #[derive(Clone, Debug)]
    struct Dsu {
        parent: Vec<usize>,
        rank: Vec<u8>,
        binding: Vec<Option<TypeExpr>>,
    }

    impl Dsu {
        fn new() -> Self {
            Self {
                parent: Vec::new(),
                rank: Vec::new(),
                binding: Vec::new(),
            }
        }

        fn make_set(&mut self) -> usize {
            let id = self.parent.len();
            self.parent.push(id);
            self.rank.push(0);
            self.binding.push(None);
            id
        }

        fn find(&mut self, x: usize) -> usize {
            if self.parent[x] != x {
                let p = self.parent[x];
                self.parent[x] = self.find(p);
            }
            self.parent[x]
        }

        fn union(&mut self, a: usize, b: usize) -> Result<usize, (TypeExpr, TypeExpr)> {
            let mut ra = self.find(a);
            let mut rb = self.find(b);
            if ra == rb {
                return Ok(ra);
            }
            if self.rank[ra] < self.rank[rb] {
                std::mem::swap(&mut ra, &mut rb);
            }
            self.parent[rb] = ra;
            if self.rank[ra] == self.rank[rb] {
                self.rank[ra] = self.rank[ra].saturating_add(1);
            }

            match (&self.binding[ra], &self.binding[rb]) {
                (Some(a), Some(b)) if a != b => return Err((a.clone(), b.clone())),
                (None, Some(b)) => self.binding[ra] = Some(b.clone()),
                _ => {}
            }
            Ok(ra)
        }

        fn bind(&mut self, var: usize, ty: TypeExpr) -> Result<(), (TypeExpr, TypeExpr)> {
            let r = self.find(var);
            if let Some(existing) = &self.binding[r] {
                if existing != &ty {
                    return Err((existing.clone(), ty));
                }
                return Ok(());
            }
            self.binding[r] = Some(ty);
            Ok(())
        }

        fn bound_type(&mut self, var: usize) -> Option<TypeExpr> {
            let r = self.find(var);
            self.binding[r].clone()
        }
    }

    fn is_generic_marker(ty: &TypeExpr) -> bool {
        matches!(ty, TypeExpr::Opaque(value) if value.eq_ignore_ascii_case("generic"))
    }

    fn upsert_string_map(meta: &mut BTreeMap<String, Value>, key: &str, port: &str, value: String) {
        let entry = meta
            .entry(key.to_string())
            .or_insert_with(|| Value::Map(Vec::new()));
        if !matches!(entry, Value::Map(_)) {
            *entry = Value::Map(Vec::new());
        }
        let Value::Map(entries) = entry else { return };
        let port_lc = port.to_ascii_lowercase();
        let mut replaced = false;
        for (k, v) in entries.iter_mut() {
            if matches!(k, Value::String(s) if s.eq_ignore_ascii_case(&port_lc)) {
                *v = Value::String(std::borrow::Cow::Owned(value.clone()));
                replaced = true;
                break;
            }
        }
        if !replaced {
            entries.push((
                Value::String(std::borrow::Cow::Owned(port_lc)),
                Value::String(std::borrow::Cow::Owned(value)),
            ));
        }
        entries.sort_by(|(ak, _), (bk, _)| {
            let a = match ak {
                Value::String(s) => s.as_ref(),
                _ => "",
            };
            let b = match bk {
                Value::String(s) => s.as_ref(),
                _ => "",
            };
            a.cmp(b)
        });
    }

    let mut vars: BTreeMap<TypeVarKey, usize> = BTreeMap::new();
    let mut dsu = Dsu::new();

    for edge in &graph.edges {
        let from_node = match graph.nodes.get(edge.from.node.0) {
            Some(n) => n,
            None => continue,
        };
        let to_node = match graph.nodes.get(edge.to.node.0) {
            Some(n) => n,
            None => continue,
        };
        let from_desc = latest_node(view, &from_node.id);
        let to_desc = latest_node(view, &to_node.id);

        let from_ty = from_desc.and_then(|d| port_type(from_node, d, &edge.from.port, false));
        let to_ty = to_desc.and_then(|d| port_type(to_node, d, &edge.to.port, true));

        if from_desc.is_none() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::NodeMissing,
                    format!("node {} not found in registry", from_node.id.0),
                )
                .in_pass("typecheck")
                .at_node(diagnostic_node_id(from_node)),
            );
            continue;
        }
        if to_desc.is_none() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::NodeMissing,
                    format!("node {} not found in registry", to_node.id.0),
                )
                .in_pass("typecheck")
                .at_node(diagnostic_node_id(to_node)),
            );
            continue;
        }

        if from_ty.is_none() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::PortMissing,
                    format!(
                        "output port `{}` not found on node {}",
                        edge.from.port, from_node.id.0
                    ),
                )
                .in_pass("typecheck")
                .at_node(diagnostic_node_id(from_node))
                .at_port(edge.from.port.clone()),
            );
        }
        if to_ty.is_none() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::PortMissing,
                    format!(
                        "input port `{}` not found on node {}",
                        edge.to.port, to_node.id.0
                    ),
                )
                .in_pass("typecheck")
                .at_node(diagnostic_node_id(to_node))
                .at_port(edge.to.port.clone()),
            );
        }

        let (Some(from_ty), Some(to_ty)) = (from_ty, to_ty) else {
            continue;
        };

        // Resolve `Opaque("generic")` as a proper type variable: graph edges constrain it.
        let from_term = if is_generic_marker(&from_ty) {
            let key = TypeVarKey {
                node: edge.from.node.0,
                is_input: false,
                port: edge.from.port.clone(),
            };
            let id = *vars.entry(key).or_insert_with(|| dsu.make_set());
            Some(id)
        } else {
            None
        };
        let to_term = if is_generic_marker(&to_ty) {
            let key = TypeVarKey {
                node: edge.to.node.0,
                is_input: true,
                port: edge.to.port.clone(),
            };
            let id = *vars.entry(key).or_insert_with(|| dsu.make_set());
            Some(id)
        } else {
            None
        };

        let conflict = match (from_term, to_term) {
            (Some(var), None) => dsu.bind(var, to_ty.clone()).err(),
            (None, Some(var)) => dsu.bind(var, from_ty.clone()).err(),
            (Some(a), Some(b)) => dsu.union(a, b).err(),
            (None, None) => None,
        };

        if let Some((a, b)) = conflict {
            let host = if is_generic_marker(&from_ty) {
                from_node
            } else {
                to_node
            };
            let port = if is_generic_marker(&from_ty) {
                edge.from.port.clone()
            } else {
                edge.to.port.clone()
            };
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::TypeMismatch,
                    format!(
                        "generic port `{}` inferred conflicting types: {:?} vs {:?} (edge {}.{} -> {}.{})",
                        port,
                        a,
                        b,
                        from_node.id.0,
                        edge.from.port,
                        to_node.id.0,
                        edge.to.port
                    ),
                )
                .in_pass("typecheck")
                .at_node(diagnostic_node_id(host))
                .at_port(port),
            );
        }
    }

    // Apply solved generic types back onto node metadata so later passes/runtime can consume them.
    for (key, var) in vars {
        let Some(ty) = dsu.bound_type(var) else {
            continue;
        };
        let Some(node) = graph.nodes.get_mut(key.node) else {
            continue;
        };
        let json = match serde_json::to_string(&ty) {
            Ok(v) => v,
            Err(_) => continue,
        };
        let meta_key = if key.is_input {
            DYNAMIC_INPUT_TYPES_KEY
        } else {
            DYNAMIC_OUTPUT_TYPES_KEY
        };
        upsert_string_map(&mut node.metadata, meta_key, &key.port, json);
    }
}

fn convert(
    graph: &mut Graph,
    registry: &daedalus_registry::store::Registry,
    view: &daedalus_registry::store::RegistryView,
    diags: &mut Vec<Diagnostic>,
    config: &PlannerConfig,
) {
    fn collect_structural_steps(
        registry: &daedalus_registry::store::Registry,
        from: &TypeExpr,
        to: &TypeExpr,
        active_features: &[String],
        allow_gpu: bool,
        steps: &mut BTreeSet<ConverterId>,
        depth: usize,
    ) -> bool {
        if from == to {
            return true;
        }
        if depth > 64 {
            return false;
        }
        if let Ok(res) =
            registry.resolve_converter_with_context(from, to, active_features, allow_gpu)
        {
            for step in res.provenance.steps {
                steps.insert(step);
            }
            return true;
        }
        match (from, to) {
            (
                TypeExpr::Scalar(ValueType::I32 | ValueType::U32),
                TypeExpr::Scalar(ValueType::Int),
            )
            | (
                TypeExpr::Scalar(ValueType::Int),
                TypeExpr::Scalar(ValueType::I32 | ValueType::U32),
            )
            | (TypeExpr::Scalar(ValueType::F32), TypeExpr::Scalar(ValueType::Float))
            | (TypeExpr::Scalar(ValueType::Float), TypeExpr::Scalar(ValueType::F32)) => true,
            (TypeExpr::Optional(a), TypeExpr::Optional(b)) => collect_structural_steps(
                registry,
                a,
                b,
                active_features,
                allow_gpu,
                steps,
                depth + 1,
            ),
            (TypeExpr::List(a), TypeExpr::List(b)) => collect_structural_steps(
                registry,
                a,
                b,
                active_features,
                allow_gpu,
                steps,
                depth + 1,
            ),
            (TypeExpr::Map(ak, av), TypeExpr::Map(bk, bv)) => {
                collect_structural_steps(
                    registry,
                    ak,
                    bk,
                    active_features,
                    allow_gpu,
                    steps,
                    depth + 1,
                ) && collect_structural_steps(
                    registry,
                    av,
                    bv,
                    active_features,
                    allow_gpu,
                    steps,
                    depth + 1,
                )
            }
            (TypeExpr::Tuple(a), TypeExpr::Tuple(b)) => {
                if a.len() != b.len() {
                    return false;
                }
                a.iter().zip(b.iter()).all(|(ai, bi)| {
                    collect_structural_steps(
                        registry,
                        ai,
                        bi,
                        active_features,
                        allow_gpu,
                        steps,
                        depth + 1,
                    )
                })
            }
            (TypeExpr::Struct(a_fields), TypeExpr::Struct(b_fields)) => {
                if a_fields.len() != b_fields.len() {
                    return false;
                }
                for bf in b_fields {
                    let Some(af) = a_fields.iter().find(|af| af.name == bf.name) else {
                        return false;
                    };
                    if !collect_structural_steps(
                        registry,
                        &af.ty,
                        &bf.ty,
                        active_features,
                        allow_gpu,
                        steps,
                        depth + 1,
                    ) {
                        return false;
                    }
                }
                true
            }
            (TypeExpr::Enum(a_vars), TypeExpr::Enum(b_vars)) => {
                if a_vars.len() != b_vars.len() {
                    return false;
                }
                for bv in b_vars {
                    let Some(av) = a_vars.iter().find(|av| av.name == bv.name) else {
                        return false;
                    };
                    match (&av.ty, &bv.ty) {
                        (None, None) => {}
                        (Some(at), Some(bt)) => {
                            if !collect_structural_steps(
                                registry,
                                at,
                                bt,
                                active_features,
                                allow_gpu,
                                steps,
                                depth + 1,
                            ) {
                                return false;
                            }
                        }
                        _ => return false,
                    }
                }
                true
            }
            _ => false,
        }
    }

    fn resolve_structural(
        registry: &daedalus_registry::store::Registry,
        from: &TypeExpr,
        to: &TypeExpr,
        active_features: &[String],
        allow_gpu: bool,
    ) -> Option<Vec<ConverterId>> {
        let mut steps = BTreeSet::new();
        if !collect_structural_steps(
            registry,
            from,
            to,
            active_features,
            allow_gpu,
            &mut steps,
            0,
        ) {
            return None;
        }
        Some(steps.into_iter().collect())
    }

    let mut converter_metadata: Vec<(String, String)> = Vec::new();
    for edge in &graph.edges {
        let from_node = match graph.nodes.get(edge.from.node.0) {
            Some(n) => n,
            None => continue,
        };
        let to_node = match graph.nodes.get(edge.to.node.0) {
            Some(n) => n,
            None => continue,
        };
        let from_desc = latest_node(view, &from_node.id);
        let to_desc = latest_node(view, &to_node.id);
        let from_ty = from_desc.and_then(|d| port_type(from_node, d, &edge.from.port, false));
        let to_ty = to_desc.and_then(|d| port_type(to_node, d, &edge.to.port, true));
        let (Some(out_ty), Some(in_ty)) = (from_ty, to_ty) else {
            continue;
        };
        if out_ty == in_ty {
            continue;
        }
        let allow_gpu = config.enable_gpu;
        let features: Vec<String> = config.active_features.clone();
        let result: Result<ConversionResolution, ()> =
            resolve_structural(registry, &out_ty, &in_ty, &features, allow_gpu)
                .map(|steps| ConversionResolution {
                    provenance: ConversionProvenance {
                        steps,
                        total_cost: 0,
                        skipped_cycles: vec![],
                        skipped_gpu: vec![],
                        skipped_features: vec![],
                    },
                })
                .ok_or(());
        match result {
            Ok(res) => {
                let mut feats = features.clone();
                feats.sort();
                let feats_str = if feats.is_empty() {
                    "none".to_string()
                } else {
                    feats.join(",")
                };
                let key = format!(
                    "converter:{}->{}:{}->{}",
                    from_node.id.0, to_node.id.0, edge.from.port, edge.to.port
                );
                let mut path: Vec<String> =
                    res.provenance.steps.iter().map(|c| c.0.clone()).collect();
                if path.is_empty() {
                    path.push("identity".into());
                }
                let value = format!(
                    "cost={};path={};features={};gpu={};skipped_gpu={:?};skipped_features={:?}",
                    res.provenance.total_cost,
                    path.join(">"),
                    feats_str,
                    allow_gpu,
                    res.provenance.skipped_gpu,
                    res.provenance.skipped_features
                );
                converter_metadata.push((key, value));
            }
            Err(_) => {
                let mut feats = features.clone();
                feats.sort();
                let feats_str = if feats.is_empty() {
                    "none".to_string()
                } else {
                    feats.join(",")
                };
                diags.push(
                    Diagnostic::new(
                        DiagnosticCode::ConverterMissing,
                        format!(
                            "no converter from {:?} to {:?} for edge {}.{} -> {}.{} [features: {}; gpu: {}]",
                            out_ty,
                            in_ty,
                            from_node.id.0,
                            edge.from.port,
                            to_node.id.0,
                            edge.to.port,
                            feats_str,
                            allow_gpu
                        ),
                    )
                    .in_pass("convert")
                    .at_node(diagnostic_node_id(to_node))
                    .at_port(edge.to.port.clone()),
                );
            }
        }
    }
    converter_metadata.sort_by(|a, b| a.0.cmp(&b.0));
    for (k, v) in converter_metadata {
        graph.metadata.insert(k, v);
    }
}
fn align(graph: &mut Graph, diags: &mut Vec<Diagnostic>) {
    // Kahn topo sort to detect cycles and emit ordering metadata.
    let n = graph.nodes.len();
    let mut indegree = vec![0usize; n];
    let mut adj: Vec<Vec<usize>> = vec![Vec::new(); n];
    for edge in &graph.edges {
        if edge.from.node.0 < n
            && edge.to.node.0 < n
            && !is_host_bridge(&graph.nodes[edge.from.node.0])
            && !is_host_bridge(&graph.nodes[edge.to.node.0])
        {
            adj[edge.from.node.0].push(edge.to.node.0);
            indegree[edge.to.node.0] += 1;
        }
    }
    let mut queue: Vec<usize> = indegree
        .iter()
        .enumerate()
        .filter(|(_, d)| **d == 0)
        .map(|(i, _)| i)
        .collect();
    let mut order = Vec::new();
    while let Some(v) = queue.pop() {
        order.push(v);
        for &nxt in &adj[v] {
            indegree[nxt] -= 1;
            if indegree[nxt] == 0 {
                queue.push(nxt);
            }
        }
    }
    if order.len() != n {
        // Cycle: collect nodes with indegree > 0 for deterministic message.
        let mut cyc_nodes: Vec<String> = indegree
            .iter()
            .enumerate()
            .filter(|(_, d)| **d > 0)
            .map(|(i, _)| graph.nodes[i].id.0.clone())
            .collect();
        cyc_nodes.sort();
        diags.push(
            Diagnostic::new(
                DiagnosticCode::ScheduleConflict,
                format!(
                    "graph contains a cycle involving nodes: {}",
                    cyc_nodes.join(",")
                ),
            )
            .in_pass("align"),
        );
    } else {
        let value = order
            .iter()
            .map(|&idx| graph.nodes[idx].id.0.clone())
            .collect::<Vec<_>>()
            .join(",");
        graph.metadata.insert("topo_order".into(), value);
    }
}
fn gpu(graph: &mut Graph, config: &PlannerConfig, diags: &mut Vec<Diagnostic>) {
    let mut gpu_reasons: Vec<String> = Vec::new();
    // If GPU is disabled, flag required nodes.
    if !config.enable_gpu {
        gpu_reasons.push("gpu-disabled".into());
        let mut gpu_nodes: Vec<String> = Vec::new();
        for node in &graph.nodes {
            if matches!(node.compute, ComputeAffinity::GpuRequired) {
                gpu_nodes.push(node.id.0.clone());
                diags.push(
                    Diagnostic::new(
                        DiagnosticCode::GpuUnsupported,
                        format!("node {} requires GPU but GPU is disabled", node.id.0),
                    )
                    .in_pass("gpu")
                    .at_node(diagnostic_node_id(node)),
                );
            }
        }
        if !gpu_nodes.is_empty() {
            graph
                .metadata
                .insert("gpu_segments".into(), gpu_nodes.join(","));
            graph
                .metadata
                .insert("gpu_why".into(), gpu_reasons.join(","));
        }
        return;
    }

    // If caps are provided, validate support.
    #[cfg(feature = "gpu")]
    if let Some(caps) = &config.gpu_caps {
        let require_format = daedalus_gpu::GpuFormat::Rgba8Unorm;
        let mut ok = true;
        let has_format = caps
            .format_features
            .iter()
            .find(|f| f.format == require_format && f.sampleable);
        if caps.queue_count == 0 || !caps.has_transfer_queue {
            ok = false;
        }
        if has_format.is_none() {
            ok = false;
        }
        if !ok {
            gpu_reasons.push(format!(
                "insufficient-caps:queues={} transfer={} format_sampleable={}",
                caps.queue_count,
                caps.has_transfer_queue,
                has_format.is_some()
            ));
            for node in &graph.nodes {
                if matches!(
                    node.compute,
                    ComputeAffinity::GpuRequired | ComputeAffinity::GpuPreferred
                ) {
                    diags.push(
                        Diagnostic::new(
                            DiagnosticCode::GpuUnsupported,
                            format!(
                                "node {} cannot run on GPU: insufficient caps (queues={}, transfer={}, format={:?} sampleable={})",
                                node.id.0,
                                caps.queue_count,
                                caps.has_transfer_queue,
                                require_format,
                                has_format.is_some()
                            ),
                        )
                        .in_pass("gpu")
                        .at_node(diagnostic_node_id(node)),
                    );
                }
            }
        }
    }

    // Record GPU segments metadata (simple grouping of contiguous GPU-pref/required nodes).
    let mut segments: Vec<Vec<String>> = Vec::new();
    let mut current: Vec<String> = Vec::new();
    for node in &graph.nodes {
        match node.compute {
            ComputeAffinity::GpuPreferred | ComputeAffinity::GpuRequired => {
                current.push(node.id.0.clone());
            }
            ComputeAffinity::CpuOnly => {
                if !current.is_empty() {
                    segments.push(current);
                    current = Vec::new();
                }
            }
        }
    }
    if !current.is_empty() {
        segments.push(current);
    }
    if !segments.is_empty() {
        let seg_strs: Vec<String> = segments.into_iter().map(|seg| seg.join("->")).collect();
        graph
            .metadata
            .insert("gpu_segments".into(), seg_strs.join("|"));
    }
    if !gpu_reasons.is_empty() {
        gpu_reasons.sort();
        gpu_reasons.dedup();
        graph
            .metadata
            .insert("gpu_why".into(), gpu_reasons.join(";"));
    }
}
fn schedule(graph: &mut Graph, _diags: &mut Vec<Diagnostic>) {
    // If topo_order exists, use it; else declared order. Attach basic priority info.
    let order = graph
        .metadata
        .get("topo_order")
        .cloned()
        .unwrap_or_else(|| {
            graph
                .nodes
                .iter()
                .map(|n| n.id.0.clone())
                .collect::<Vec<_>>()
                .join(",")
        });
    graph.metadata.insert("schedule_order".into(), order);

    // Prefer GPU-required nodes first within same topo layer (simple heuristic).
    let mut priorities: Vec<(String, u8)> = graph
        .nodes
        .iter()
        .map(|n| {
            let p = match n.compute {
                ComputeAffinity::GpuPreferred => 1,
                ComputeAffinity::GpuRequired | ComputeAffinity::CpuOnly => 2,
            };
            (n.id.0.clone(), p)
        })
        .collect();
    priorities.sort_by(|a, b| a.1.cmp(&b.1).then_with(|| a.0.cmp(&b.0)));
    let pr_str = priorities
        .into_iter()
        .map(|(id, p)| format!("{id}:{p}"))
        .collect::<Vec<_>>()
        .join(",");
    graph.metadata.insert("schedule_priority".into(), pr_str);
}
fn lint(input: &PlannerInput<'_>, diags: &mut Vec<Diagnostic>) {
    let n = input.graph.nodes.len();
    let mut incoming: Vec<usize> = vec![0; n];
    let mut outgoing: Vec<usize> = vec![0; n];
    for e in &input.graph.edges {
        if e.from.node.0 < n {
            outgoing[e.from.node.0] += 1;
        }
        if e.to.node.0 < n {
            incoming[e.to.node.0] += 1;
        }
    }

    for (idx, node) in input.graph.nodes.iter().enumerate() {
        if incoming[idx] == 0 && !node.inputs.is_empty() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::LintWarning,
                    format!(
                        "node {} has unconnected inputs: {}",
                        node.id.0,
                        node.inputs.join(",")
                    ),
                )
                .in_pass("lint")
                .at_node(diagnostic_node_id(node)),
            );
        }
        if outgoing[idx] == 0 && !node.outputs.is_empty() {
            diags.push(
                Diagnostic::new(
                    DiagnosticCode::LintWarning,
                    format!(
                        "node {} has unused outputs: {}",
                        node.id.0,
                        node.outputs.join(",")
                    ),
                )
                .in_pass("lint")
                .at_node(diagnostic_node_id(node)),
            );
        }
    }
}

fn port_type(
    node: &NodeInstance,
    desc: &NodeDescriptor,
    name: &str,
    is_input: bool,
) -> Option<TypeExpr> {
    fn is_generic_marker(ty: &TypeExpr) -> bool {
        matches!(ty, TypeExpr::Opaque(value) if value.eq_ignore_ascii_case("generic"))
    }

    fn resolve_override(
        meta: &std::collections::BTreeMap<String, Value>,
        key: &str,
        port: &str,
    ) -> Option<TypeExpr> {
        let Value::Map(entries) = meta.get(key)? else {
            return None;
        };
        let port_lc = port.to_ascii_lowercase();
        let (_, value) = entries
            .iter()
            .find(|(k, _)| matches!(k, Value::String(s) if s.eq_ignore_ascii_case(&port_lc)))?;
        let Value::String(json) = value else {
            return None;
        };
        serde_json::from_str::<TypeExpr>(json).ok()
    }

    if is_input {
        if let Some(ty) = desc.input_ty_for(name) {
            if is_generic_marker(ty)
                && let Some(solved) =
                    resolve_override(&node.metadata, DYNAMIC_INPUT_TYPES_KEY, name)
            {
                return Some(solved);
            }
            return Some(ty.clone());
        }
        if let Some(ty) = resolve_override(&node.metadata, DYNAMIC_INPUT_TYPES_KEY, name) {
            return Some(ty);
        }
    } else if let Some(port) = desc.outputs.iter().find(|p| p.name == name) {
        if is_generic_marker(&port.ty)
            && let Some(solved) = resolve_override(&node.metadata, DYNAMIC_OUTPUT_TYPES_KEY, name)
        {
            return Some(solved);
        }
        return Some(port.ty.clone());
    } else if let Some(ty) = resolve_override(&node.metadata, DYNAMIC_OUTPUT_TYPES_KEY, name) {
        return Some(ty);
    }
    let key = if is_input {
        "dynamic_inputs"
    } else {
        "dynamic_outputs"
    };
    let resolve_meta = |meta: &std::collections::BTreeMap<String, Value>| match meta.get(key) {
        Some(Value::String(value)) if !value.trim().is_empty() => {
            Some(TypeExpr::Opaque(value.trim().to_string()))
        }
        _ => None,
    };
    // Dynamic port declarations are trusted only from the registry descriptor, not per-node
    // graph metadata (which may come from untrusted UI/clients).
    resolve_meta(&desc.metadata)
}