clawft-kernel 0.5.4

//! Cluster membership and node fabric.
//!
//! Defines types for multi-node WeftOS clusters where agents
//! can migrate between nodes. Each node is a WeftOS kernel
//! instance -- native binary on cloud/edge, or WASM in a browser.
//!
//! # Feature Gate
//!
//! All types compile unconditionally. Actual peer discovery,
//! health monitoring, and cross-node communication require the
//! `cluster` feature flag and a distributed networking layer.

use std::collections::HashMap;
use std::time::Instant;

use chrono::{DateTime, Utc};
use dashmap::DashMap;
use serde::{Deserialize, Serialize};
use tracing::{debug, warn};

/// Unique node identifier (UUID or DID string).
pub type NodeId = String;

/// Node platform type.
#[non_exhaustive]
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum NodePlatform {
    /// Native binary on a cloud VM or bare metal server.
    CloudNative,
    /// Native binary on an edge device.
    Edge,
    /// WASM module running in a browser tab.
    Browser,
    /// WASI module in a container.
    Wasi,
    /// Custom platform label.
    Custom(String),
}

impl std::fmt::Display for NodePlatform {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            NodePlatform::CloudNative => write!(f, "cloud-native"),
            NodePlatform::Edge => write!(f, "edge"),
            NodePlatform::Browser => write!(f, "browser"),
            NodePlatform::Wasi => write!(f, "wasi"),
            NodePlatform::Custom(name) => write!(f, "custom({name})"),
        }
    }
}

/// Node health state.
#[non_exhaustive]
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum NodeState {
    /// Node is joining the cluster.
    Joining,
    /// Node is healthy and active.
    Active,
    /// Node is suspected unreachable (missed heartbeats).
    Suspect,
    /// Node has been confirmed unreachable.
    Unreachable,
    /// Node is gracefully leaving the cluster.
    Leaving,
    /// Node has left the cluster.
    Left,
}

impl std::fmt::Display for NodeState {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            NodeState::Joining => write!(f, "joining"),
            NodeState::Active => write!(f, "active"),
            NodeState::Suspect => write!(f, "suspect"),
            NodeState::Unreachable => write!(f, "unreachable"),
            NodeState::Leaving => write!(f, "leaving"),
            NodeState::Left => write!(f, "left"),
        }
    }
}

/// Information about a peer node in the cluster.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PeerNode {
    /// Unique node identifier.
    pub id: NodeId,

    /// Human-readable node name.
    pub name: String,

    /// Node platform.
    pub platform: NodePlatform,

    /// Current state in the cluster.
    pub state: NodeState,

    /// Network address for direct communication.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub address: Option<String>,

    /// When this node was first seen.
    pub first_seen: DateTime<Utc>,

    /// When the last heartbeat was received.
    pub last_heartbeat: DateTime<Utc>,

    /// Capabilities this node advertises.
    #[serde(default)]
    pub capabilities: Vec<String>,

    /// Labels for scheduling and filtering.
    #[serde(default)]
    pub labels: HashMap<String, String>,
}

/// Cluster configuration.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ClusterConfig {
    /// This node's identifier.
    pub node_id: NodeId,

    /// This node's display name.
    #[serde(default = "default_node_name")]
    pub node_name: String,

    /// This node's platform type.
    #[serde(default = "default_platform")]
    pub platform: NodePlatform,

    /// Heartbeat interval in seconds.
    #[serde(default = "default_heartbeat_interval")]
    pub heartbeat_interval_secs: u64,

    /// How many missed heartbeats before marking a node suspect.
    #[serde(default = "default_suspect_threshold")]
    pub suspect_threshold: u32,

    /// How many missed heartbeats before marking a node unreachable.
    #[serde(default = "default_unreachable_threshold")]
    pub unreachable_threshold: u32,

    /// Maximum cluster size (0 = unlimited).
    #[serde(default)]
    pub max_nodes: u32,

    /// Address to bind the mesh listener (e.g., "0.0.0.0:9470").
    #[serde(default)]
    pub bind_address: Option<String>,

    /// Seed peers for bootstrap discovery.
    #[serde(default)]
    pub seed_peers: Vec<String>,

    /// Path to Ed25519 identity key file.
    #[serde(default)]
    pub identity_key_path: Option<std::path::PathBuf>,
}

fn default_node_name() -> String {
    "local".into()
}

fn default_platform() -> NodePlatform {
    NodePlatform::CloudNative
}

fn default_heartbeat_interval() -> u64 {
    5
}

fn default_suspect_threshold() -> u32 {
    3
}

fn default_unreachable_threshold() -> u32 {
    10
}

impl Default for ClusterConfig {
    fn default() -> Self {
        Self {
            node_id: uuid::Uuid::new_v4().to_string(),
            node_name: default_node_name(),
            platform: default_platform(),
            heartbeat_interval_secs: default_heartbeat_interval(),
            suspect_threshold: default_suspect_threshold(),
            unreachable_threshold: default_unreachable_threshold(),
            max_nodes: 0,
            bind_address: None,
            seed_peers: Vec::new(),
            identity_key_path: None,
        }
    }
}

// ── ECC capability advertisement (K3c) ────────────────────────────

/// ECC capabilities advertised by a cluster node.
///
/// Populated during boot-time calibration and advertised to peers
/// so they can route ECC-related requests to capable nodes.
#[cfg(feature = "ecc")]
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct NodeEccCapability {
    /// Calibrated cognitive tick interval (milliseconds).
    pub tick_interval_ms: u32,
    /// 95th percentile compute time per tick (microseconds).
    pub compute_p95_us: u32,
    /// Headroom ratio (actual_compute / budget).
    pub headroom_ratio: f32,
    /// Number of vectors in the HNSW index.
    pub hnsw_vector_count: u32,
    /// Number of edges in the causal graph.
    pub causal_edge_count: u32,
    /// Whether this node can perform spectral analysis.
    pub spectral_capable: bool,
    /// Unix timestamp when calibration was performed.
    pub calibrated_at: u64,
}

// ── Node identity (K6 mesh networking) ─────────────────────────────

/// Node identity derived from Ed25519 keypair.
///
/// The `node_id` is derived as `hex(SHA-256(pubkey)[0..16])`,
/// providing a stable, compact identifier tied to the cryptographic key.
#[cfg(any(feature = "mesh", feature = "exochain"))]
pub struct NodeIdentity {
    /// Ed25519 signing key (private).
    keypair: ed25519_dalek::SigningKey,
    /// Derived node identifier.
    node_id: String,
}

#[cfg(any(feature = "mesh", feature = "exochain"))]
impl NodeIdentity {
    /// Generate a new random identity.
    pub fn generate() -> Self {
        use sha2::Digest;

        let mut csprng = rand::thread_rng();
        let keypair = ed25519_dalek::SigningKey::generate(&mut csprng);
        let pubkey_bytes = keypair.verifying_key().to_bytes();

        let hash = sha2::Sha256::digest(pubkey_bytes);
        let node_id = hash[..16]
            .iter()
            .fold(String::with_capacity(32), |mut s, b| {
                use std::fmt::Write;
                let _ = write!(s, "{b:02x}");
                s
            });

        Self { keypair, node_id }
    }

    /// Get this node's identifier.
    pub fn node_id(&self) -> &str {
        &self.node_id
    }

    /// Get the public verification key.
    pub fn public_key(&self) -> ed25519_dalek::VerifyingKey {
        self.keypair.verifying_key()
    }

    /// Sign arbitrary data with this node's private key.
    pub fn sign(&self, data: &[u8]) -> ed25519_dalek::Signature {
        use ed25519_dalek::Signer;
        self.keypair.sign(data)
    }
}

/// Cluster membership errors.
#[non_exhaustive]
#[derive(Debug, thiserror::Error)]
pub enum ClusterError {
    /// Node already in the cluster.
    #[error("node already exists: '{node_id}'")]
    NodeAlreadyExists {
        /// Node ID.
        node_id: NodeId,
    },

    /// Node not found.
    #[error("node not found: '{node_id}'")]
    NodeNotFound {
        /// Node ID.
        node_id: NodeId,
    },

    /// Cluster is at maximum capacity.
    #[error("cluster full: max {max} nodes")]
    ClusterFull {
        /// Maximum node count.
        max: u32,
    },

    /// Mesh networking error.
    #[error("mesh error: {0}")]
    Mesh(String),

    /// Authentication failed during cluster join.
    #[error("authentication failed: {0}")]
    AuthFailed(String),

    /// Invalid state transition.
    #[error("invalid node state transition: {from} -> {to}")]
    InvalidTransition {
        /// Current state.
        from: String,
        /// Requested state.
        to: String,
    },

    /// Peer additions are too frequent (rate limited).
    #[error("rate limited: peer additions too frequent")]
    RateLimited,
}

/// Cluster membership tracker.
///
/// Tracks which nodes are part of the cluster, their health state,
/// and capabilities. Actual peer discovery and heartbeat monitoring
/// require a networking layer not included here.
/// Known valid capabilities for cluster nodes.
const KNOWN_CAPABILITIES: &[&str] = &[
    "ipc", "chain", "tree", "governance", "ecc", "wasm", "containers", "apps",
    "mesh", "discovery", "heartbeat", "compute",
];

/// Validate peer capabilities against the known set.
/// Returns unknown capabilities (if any).
fn validate_capabilities(capabilities: &[String]) -> Vec<String> {
    capabilities
        .iter()
        .filter(|c| !KNOWN_CAPABILITIES.contains(&c.as_str()))
        .cloned()
        .collect()
}

pub struct ClusterMembership {
    config: ClusterConfig,
    peers: DashMap<NodeId, PeerNode>,
    /// Timestamp of last peer addition (rate limiting).
    last_peer_add: std::sync::Mutex<Option<Instant>>,
    /// Minimum interval between peer additions.
    min_peer_add_interval: std::time::Duration,
}

impl ClusterMembership {
    /// Create a new cluster membership tracker.
    pub fn new(config: ClusterConfig) -> Self {
        Self {
            config,
            peers: DashMap::new(),
            last_peer_add: std::sync::Mutex::new(None),
            min_peer_add_interval: std::time::Duration::from_millis(100),
        }
    }

    /// Set the minimum interval between peer additions (builder style).
    pub fn with_min_peer_interval(mut self, interval: std::time::Duration) -> Self {
        self.min_peer_add_interval = interval;
        self
    }

    /// Get the cluster configuration.
    pub fn config(&self) -> &ClusterConfig {
        &self.config
    }

    /// Get this node's ID.
    pub fn local_node_id(&self) -> &str {
        &self.config.node_id
    }

    /// Register a peer node.
    ///
    /// Rate-limited to at most one addition per `min_peer_add_interval`
    /// (default 100 ms) to prevent join-flood attacks.
    pub fn add_peer(&self, peer: PeerNode) -> Result<(), ClusterError> {
        // Rate-limit peer additions.
        {
            let mut last = self.last_peer_add.lock().unwrap();
            if let Some(ts) = *last {
                if ts.elapsed() < self.min_peer_add_interval {
                    return Err(ClusterError::RateLimited);
                }
            }
            *last = Some(Instant::now());
        }

        if self.peers.contains_key(&peer.id) {
            return Err(ClusterError::NodeAlreadyExists { node_id: peer.id });
        }

        if self.config.max_nodes > 0 && self.peers.len() as u32 >= self.config.max_nodes {
            return Err(ClusterError::ClusterFull {
                max: self.config.max_nodes,
            });
        }

        // Validate capabilities -- warn on unknown but still allow (forward compat).
        let unknown = validate_capabilities(&peer.capabilities);
        if !unknown.is_empty() {
            warn!(
                node_id = %peer.id,
                unknown_capabilities = ?unknown,
                "peer advertises unknown capabilities"
            );
        }

        debug!(node_id = %peer.id, name = %peer.name, "adding peer to cluster");
        self.peers.insert(peer.id.clone(), peer);
        Ok(())
    }

    /// Remove a peer node.
    pub fn remove_peer(&self, node_id: &str) -> Result<PeerNode, ClusterError> {
        self.peers
            .remove(node_id)
            .map(|(_, peer)| peer)
            .ok_or_else(|| ClusterError::NodeNotFound {
                node_id: node_id.to_owned(),
            })
    }

    /// Update a peer's state.
    pub fn update_state(&self, node_id: &str, new_state: NodeState) -> Result<(), ClusterError> {
        let mut entry = self
            .peers
            .get_mut(node_id)
            .ok_or_else(|| ClusterError::NodeNotFound {
                node_id: node_id.to_owned(),
            })?;
        entry.state = new_state;
        Ok(())
    }

    /// Record a heartbeat from a peer.
    pub fn heartbeat(&self, node_id: &str) -> Result<(), ClusterError> {
        let mut entry = self
            .peers
            .get_mut(node_id)
            .ok_or_else(|| ClusterError::NodeNotFound {
                node_id: node_id.to_owned(),
            })?;
        entry.last_heartbeat = Utc::now();
        if entry.state == NodeState::Suspect {
            entry.state = NodeState::Active;
        }
        Ok(())
    }

    /// Get a snapshot of a peer's state.
    pub fn get_peer(&self, node_id: &str) -> Option<PeerNode> {
        self.peers.get(node_id).map(|e| e.value().clone())
    }

    /// List all peers with their states.
    pub fn list_peers(&self) -> Vec<(NodeId, NodeState, NodePlatform)> {
        self.peers
            .iter()
            .map(|e| (e.key().clone(), e.state.clone(), e.platform.clone()))
            .collect()
    }

    /// Count peers by state.
    pub fn count_by_state(&self, state: &NodeState) -> usize {
        self.peers.iter().filter(|e| &e.state == state).count()
    }

    /// Count total peers.
    pub fn len(&self) -> usize {
        self.peers.len()
    }

    /// Check if cluster has no peers.
    pub fn is_empty(&self) -> bool {
        self.peers.is_empty()
    }

    /// Add a peer and optionally create a resource tree node.
    #[cfg(feature = "exochain")]
    pub fn add_peer_with_tree(
        &self,
        peer: PeerNode,
        tree: &std::sync::Mutex<exo_resource_tree::ResourceTree>,
    ) -> Result<(), ClusterError> {
        let peer_name = peer.name.clone();
        self.add_peer(peer)?;

        // Create tree node for this peer
        let mut tree = tree.lock().unwrap();
        let peer_id =
            exo_resource_tree::ResourceId::new(format!("/network/peers/{peer_name}"));
        let parent = exo_resource_tree::ResourceId::new("/network/peers");
        if let Err(e) = tree.insert(peer_id, exo_resource_tree::ResourceKind::Device, parent) {
            tracing::debug!(peer = %peer_name, error = %e, "failed to create tree node for peer");
        }

        Ok(())
    }

    /// Get all active peer node IDs.
    pub fn active_peers(&self) -> Vec<NodeId> {
        self.peers
            .iter()
            .filter(|e| e.state == NodeState::Active)
            .map(|e| e.key().clone())
            .collect()
    }
}

// ── ClusterService (native coordinator layer) ────────────────────────
//
// Wraps ruvector's ClusterManager behind the `cluster` feature flag.
// Only runs on native coordinator nodes; browser/edge nodes participate
// through the universal ClusterMembership layer via WebSocket.

#[cfg(feature = "cluster")]
mod cluster_service {
    use std::sync::Arc;
    use std::time::Duration;

    use async_trait::async_trait;
    use tracing::{debug, info};

    use ruvector_cluster::{
        ClusterConfig as RuvectorClusterConfig, ClusterManager, ClusterNode, DiscoveryService,
        NodeStatus, ShardInfo, StaticDiscovery,
    };

    use crate::cluster::{ClusterMembership, NodePlatform, NodeState, PeerNode};
    use crate::health::HealthStatus;
    use crate::service::{ServiceType, SystemService};
    use clawft_types::config::ClusterNetworkConfig;

    /// Native coordinator cluster service.
    ///
    /// Wraps ruvector's [`ClusterManager`] and syncs discovered nodes
    /// into the kernel's universal [`ClusterMembership`] tracker.
    pub struct ClusterService {
        manager: ClusterManager,
        membership: Arc<ClusterMembership>,
        config: ClusterNetworkConfig,
    }

    impl ClusterService {
        /// Create a new cluster service.
        ///
        /// `membership` is the kernel's universal peer tracker that
        /// all platforms share. The ClusterService syncs ruvector
        /// native node state into it.
        pub fn new(
            config: ClusterNetworkConfig,
            node_id: String,
            discovery: Box<dyn DiscoveryService>,
            membership: Arc<ClusterMembership>,
        ) -> Result<Self, ruvector_cluster::ClusterError> {
            let ruvector_config = RuvectorClusterConfig {
                replication_factor: config.replication_factor,
                shard_count: config.shard_count,
                heartbeat_interval: Duration::from_secs(config.heartbeat_interval_secs),
                node_timeout: Duration::from_secs(config.node_timeout_secs),
                enable_consensus: config.enable_consensus,
                min_quorum_size: config.min_quorum_size,
            };

            let manager = ClusterManager::new(ruvector_config, node_id, discovery)?;

            Ok(Self {
                manager,
                membership,
                config,
            })
        }

        /// Create with default config and static (empty) discovery.
        pub fn with_defaults(
            node_id: String,
            membership: Arc<ClusterMembership>,
        ) -> Result<Self, ruvector_cluster::ClusterError> {
            let config = ClusterNetworkConfig::default();
            let discovery = Box::new(StaticDiscovery::new(vec![]));
            Self::new(config, node_id, discovery, membership)
        }

        /// Sync ruvector's native node list into the kernel's
        /// [`ClusterMembership`] tracker.
        ///
        /// Converts ruvector [`ClusterNode`] entries into kernel
        /// [`PeerNode`] entries, mapping `SocketAddr` → `String`
        /// and `NodeStatus` → `NodeState`.
        pub fn sync_to_membership(&self) {
            let nodes = self.manager.list_nodes();
            for node in &nodes {
                let peer = Self::cluster_node_to_peer(node);
                if self.membership.get_peer(&peer.id).is_some() {
                    // Update existing peer's state
                    let new_state = Self::map_status(node.status);
                    let _ = self.membership.update_state(&peer.id, new_state);
                    let _ = self.membership.heartbeat(&peer.id);
                } else {
                    // Add new peer
                    if let Err(e) = self.membership.add_peer(peer) {
                        debug!(error = %e, "failed to sync node to membership");
                    }
                }
            }
        }

        /// Get the cluster network configuration.
        pub fn config(&self) -> &ClusterNetworkConfig {
            &self.config
        }

        /// Get the underlying cluster manager (for advanced operations).
        pub fn manager(&self) -> &ClusterManager {
            &self.manager
        }

        /// Get cluster statistics.
        pub fn stats(&self) -> ruvector_cluster::ClusterStats {
            self.manager.get_stats()
        }

        /// List all shards.
        pub fn list_shards(&self) -> Vec<ShardInfo> {
            self.manager.list_shards()
        }

        /// List all ruvector nodes.
        pub fn list_nodes(&self) -> Vec<ClusterNode> {
            self.manager.list_nodes()
        }

        /// Convert a ruvector `NodeStatus` to a kernel `NodeState`.
        fn map_status(status: NodeStatus) -> NodeState {
            match status {
                NodeStatus::Leader | NodeStatus::Follower | NodeStatus::Candidate => {
                    NodeState::Active
                }
                NodeStatus::Offline => NodeState::Unreachable,
            }
        }

        /// Convert a ruvector `ClusterNode` to a kernel `PeerNode`.
        fn cluster_node_to_peer(node: &ClusterNode) -> PeerNode {
            PeerNode {
                id: node.node_id.clone(),
                name: node
                    .metadata
                    .get("name")
                    .cloned()
                    .unwrap_or_else(|| node.node_id.clone()),
                platform: NodePlatform::CloudNative,
                state: Self::map_status(node.status),
                address: Some(node.address.to_string()),
                first_seen: node.last_seen, // best approximation
                last_heartbeat: node.last_seen,
                capabilities: Vec::new(),
                labels: node.metadata.clone(),
            }
        }
    }

    #[async_trait]
    impl SystemService for ClusterService {
        fn name(&self) -> &str {
            "cluster"
        }

        fn service_type(&self) -> ServiceType {
            ServiceType::Core
        }

        async fn start(&self) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
            info!("starting cluster service");
            self.manager
                .start()
                .await
                .map_err(|e| -> Box<dyn std::error::Error + Send + Sync> { Box::new(e) })?;
            self.sync_to_membership();
            info!(
                nodes = self.manager.list_nodes().len(),
                shards = self.manager.list_shards().len(),
                "cluster service started"
            );
            Ok(())
        }

        async fn stop(&self) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
            info!("stopping cluster service");
            // Mark self as leaving in membership
            let local_id = self.membership.local_node_id().to_owned();
            let _ = self.membership.update_state(&local_id, NodeState::Left);
            Ok(())
        }

        async fn health_check(&self) -> HealthStatus {
            let stats = self.manager.get_stats();
            if stats.healthy_nodes > 0 {
                HealthStatus::Healthy
            } else {
                HealthStatus::Degraded("no healthy cluster nodes".into())
            }
        }
    }
}

#[cfg(feature = "cluster")]
pub use cluster_service::ClusterService;

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

    fn make_peer(id: &str, name: &str) -> PeerNode {
        PeerNode {
            id: id.into(),
            name: name.into(),
            platform: NodePlatform::CloudNative,
            state: NodeState::Active,
            address: Some("10.0.0.1:8080".into()),
            first_seen: Utc::now(),
            last_heartbeat: Utc::now(),
            capabilities: vec!["compute".into()],
            labels: HashMap::from([("region".into(), "us-east".into())]),
        }
    }

    #[test]
    fn default_config() {
        let config = ClusterConfig::default();
        assert_eq!(config.node_name, "local");
        assert_eq!(config.heartbeat_interval_secs, 5);
        assert_eq!(config.suspect_threshold, 3);
    }

    #[test]
    fn config_serde_roundtrip() {
        let config = ClusterConfig {
            node_id: "node-1".into(),
            node_name: "primary".into(),
            platform: NodePlatform::Edge,
            heartbeat_interval_secs: 10,
            suspect_threshold: 5,
            unreachable_threshold: 15,
            max_nodes: 100,
            ..Default::default()
        };
        let json = serde_json::to_string(&config).unwrap();
        let restored: ClusterConfig = serde_json::from_str(&json).unwrap();
        assert_eq!(restored.node_name, "primary");
        assert_eq!(restored.max_nodes, 100);
    }

    #[test]
    fn node_platform_display() {
        assert_eq!(NodePlatform::CloudNative.to_string(), "cloud-native");
        assert_eq!(NodePlatform::Browser.to_string(), "browser");
        assert_eq!(
            NodePlatform::Custom("k8s".into()).to_string(),
            "custom(k8s)"
        );
    }

    #[test]
    fn node_state_display() {
        assert_eq!(NodeState::Active.to_string(), "active");
        assert_eq!(NodeState::Suspect.to_string(), "suspect");
        assert_eq!(NodeState::Unreachable.to_string(), "unreachable");
    }

    /// Helper: create a ClusterMembership with rate limiting disabled for tests.
    fn make_cluster(config: ClusterConfig) -> ClusterMembership {
        ClusterMembership::new(config)
            .with_min_peer_interval(std::time::Duration::ZERO)
    }

    #[test]
    fn add_and_list_peers() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        cluster.add_peer(make_peer("node-2", "beta")).unwrap();

        let peers = cluster.list_peers();
        assert_eq!(peers.len(), 2);
    }

    #[test]
    fn add_duplicate_fails() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        assert!(matches!(
            cluster.add_peer(make_peer("node-1", "alpha-dup")),
            Err(ClusterError::NodeAlreadyExists { .. })
        ));
    }

    #[test]
    fn cluster_full() {
        let config = ClusterConfig {
            max_nodes: 1,
            ..Default::default()
        };
        let cluster = make_cluster(config);
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        assert!(matches!(
            cluster.add_peer(make_peer("node-2", "beta")),
            Err(ClusterError::ClusterFull { .. })
        ));
    }

    #[test]
    fn remove_peer() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        let removed = cluster.remove_peer("node-1").unwrap();
        assert_eq!(removed.name, "alpha");
        assert!(cluster.is_empty());
    }

    #[test]
    fn remove_nonexistent_fails() {
        let cluster = make_cluster(ClusterConfig::default());
        assert!(matches!(
            cluster.remove_peer("nope"),
            Err(ClusterError::NodeNotFound { .. })
        ));
    }

    #[test]
    fn update_state() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        cluster.update_state("node-1", NodeState::Suspect).unwrap();
        let peer = cluster.get_peer("node-1").unwrap();
        assert_eq!(peer.state, NodeState::Suspect);
    }

    #[test]
    fn heartbeat_clears_suspect() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        cluster.update_state("node-1", NodeState::Suspect).unwrap();
        cluster.heartbeat("node-1").unwrap();
        let peer = cluster.get_peer("node-1").unwrap();
        assert_eq!(peer.state, NodeState::Active);
    }

    #[test]
    fn count_by_state() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        cluster.add_peer(make_peer("node-2", "beta")).unwrap();
        cluster.update_state("node-2", NodeState::Suspect).unwrap();
        assert_eq!(cluster.count_by_state(&NodeState::Active), 1);
        assert_eq!(cluster.count_by_state(&NodeState::Suspect), 1);
    }

    #[test]
    fn active_peers() {
        let cluster = make_cluster(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();
        cluster.add_peer(make_peer("node-2", "beta")).unwrap();
        cluster.update_state("node-2", NodeState::Leaving).unwrap();
        let active = cluster.active_peers();
        assert_eq!(active.len(), 1);
        assert_eq!(active[0], "node-1");
    }

    #[test]
    fn peer_serde_roundtrip() {
        let peer = make_peer("node-1", "alpha");
        let json = serde_json::to_string(&peer).unwrap();
        let restored: PeerNode = serde_json::from_str(&json).unwrap();
        assert_eq!(restored.id, "node-1");
        assert_eq!(restored.capabilities, vec!["compute"]);
    }

    #[test]
    fn cluster_error_display() {
        let err = ClusterError::NodeNotFound {
            node_id: "node-1".into(),
        };
        assert!(err.to_string().contains("node-1"));

        let err = ClusterError::ClusterFull { max: 10 };
        assert!(err.to_string().contains("10"));
    }

    #[test]
    fn mesh_and_auth_error_display() {
        let err = ClusterError::Mesh("connection refused".into());
        assert!(err.to_string().contains("connection refused"));

        let err = ClusterError::AuthFailed("bad signature".into());
        assert!(err.to_string().contains("bad signature"));
    }

    #[test]
    fn default_config_new_fields() {
        let config = ClusterConfig::default();
        assert!(config.bind_address.is_none());
        assert!(config.seed_peers.is_empty());
        assert!(config.identity_key_path.is_none());
    }

    #[test]
    fn rate_limited_peer_additions() {
        // Use the default 100ms rate limit (do NOT use make_cluster here).
        let cluster = ClusterMembership::new(ClusterConfig::default());
        cluster.add_peer(make_peer("node-1", "alpha")).unwrap();

        // Second add immediately should be rate limited.
        let result = cluster.add_peer(make_peer("node-2", "beta"));
        assert!(
            matches!(result, Err(ClusterError::RateLimited)),
            "expected RateLimited, got {result:?}"
        );
    }

    #[test]
    fn rate_limited_error_display() {
        let err = ClusterError::RateLimited;
        assert!(err.to_string().contains("rate limited"));
    }

    #[test]
    fn validate_known_capabilities() {
        let known = vec!["ipc".into(), "mesh".into(), "chain".into()];
        let unknown = validate_capabilities(&known);
        assert!(unknown.is_empty());
    }

    #[test]
    fn validate_unknown_capabilities() {
        let caps = vec!["ipc".into(), "teleport".into(), "quantum".into()];
        let unknown = validate_capabilities(&caps);
        assert_eq!(unknown, vec!["teleport", "quantum"]);
    }

    #[test]
    fn add_peer_with_unknown_capabilities_succeeds() {
        let cluster = make_cluster(ClusterConfig::default());
        let mut peer = make_peer("node-1", "alpha");
        peer.capabilities = vec!["ipc".into(), "teleport".into()];
        // Should succeed (warning logged, but not rejected).
        cluster.add_peer(peer).unwrap();
        assert_eq!(cluster.len(), 1);
    }
}

#[cfg(test)]
#[cfg(any(feature = "mesh", feature = "exochain"))]
mod mesh_tests {
    use super::*;

    #[test]
    fn node_identity_unique_ids() {
        let id1 = NodeIdentity::generate();
        let id2 = NodeIdentity::generate();
        assert_ne!(id1.node_id(), id2.node_id());
    }

    #[test]
    fn node_identity_sign_verify() {
        use ed25519_dalek::Verifier;

        let identity = NodeIdentity::generate();
        let data = b"hello mesh";
        let sig = identity.sign(data);
        assert!(identity.public_key().verify(data, &sig).is_ok());
    }

    #[test]
    fn node_identity_id_is_32_hex_chars() {
        let identity = NodeIdentity::generate();
        let nid = identity.node_id();
        assert_eq!(nid.len(), 32, "node_id should be 32 hex chars (16 bytes)");
        assert!(
            nid.chars().all(|c| c.is_ascii_hexdigit()),
            "node_id must be hex: {nid}"
        );
    }
}