diff --git a/bootstrap/src/host/health.rs b/bootstrap/src/host/health.rs
new file mode 100644
index 00000000..e74053c8
--- /dev/null
+++ b/bootstrap/src/host/health.rs
@@ -0,0 +1,282 @@
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub enum Health {
+    Healthy = 3,
+    Degraded = 2,
+    Unhealthy = 1,
+    Critical = 0,
+}
+
+impl std::fmt::Display for Health {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Health::Healthy => write!(f, "healthy"),
+            Health::Degraded => write!(f, "degraded"),
+            Health::Unhealthy => write!(f, "unhealthy"),
+            Health::Critical => write!(f, "critical"),
+        }
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Subsystem {
+    Transport,
+    Session,
+    Pipeline,
+    Watchdog,
+    Memory,
+    Firmware,
+}
+
+impl std::fmt::Display for Subsystem {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Subsystem::Transport => write!(f, "transport"),
+            Subsystem::Session => write!(f, "session"),
+            Subsystem::Pipeline => write!(f, "pipeline"),
+            Subsystem::Watchdog => write!(f, "watchdog"),
+            Subsystem::Memory => write!(f, "memory"),
+            Subsystem::Firmware => write!(f, "firmware"),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct SubsystemHealth {
+    pub subsystem: Subsystem,
+    pub health: Health,
+    pub message: String,
+    pub timestamp_us: u64,
+}
+
+impl SubsystemHealth {
+    pub fn new(subsystem: Subsystem, health: Health, message: &str, timestamp_us: u64) -> Self {
+        Self {
+            subsystem,
+            health,
+            message: message.to_string(),
+            timestamp_us,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct HealthMonitor {
+    subsystems: Vec<SubsystemHealth>,
+    checks: u64,
+    last_check_us: u64,
+}
+
+impl HealthMonitor {
+    pub fn new() -> Self {
+        Self {
+            subsystems: Vec::new(),
+            checks: 0,
+            last_check_us: 0,
+        }
+    }
+
+    pub fn report(&mut self, report: SubsystemHealth) {
+        if let Some(existing) = self.subsystems.iter_mut().find(|s| s.subsystem == report.subsystem) {
+            *existing = report;
+        } else {
+            self.subsystems.push(report);
+        }
+    }
+
+    pub fn get(&self, subsystem: Subsystem) -> Option<&SubsystemHealth> {
+        self.subsystems.iter().find(|s| s.subsystem == subsystem)
+    }
+
+    pub fn overall(&self) -> Health {
+        self.subsystems
+            .iter()
+            .map(|s| s.health)
+            .min()
+            .unwrap_or(Health::Healthy)
+    }
+
+    pub fn score(&self) -> u8 {
+        let total = self.subsystems.len() as u32;
+        if total == 0 {
+            return 100;
+        }
+        let sum: u32 = self.subsystems.iter().map(|s| s.health as u32).sum();
+        ((sum * 100) / (total * (Health::Healthy as u32))) as u8
+    }
+
+    pub fn degraded_subsystems(&self) -> Vec<&SubsystemHealth> {
+        self.subsystems
+            .iter()
+            .filter(|s| s.health < Health::Healthy)
+            .collect()
+    }
+
+    pub fn check(&mut self, now_us: u64) -> Health {
+        self.checks += 1;
+        self.last_check_us = now_us;
+        self.overall()
+    }
+
+    pub fn checks(&self) -> u64 {
+        self.checks
+    }
+
+    pub fn last_check_us(&self) -> u64 {
+        self.last_check_us
+    }
+
+    pub fn subsystem_count(&self) -> usize {
+        self.subsystems.len()
+    }
+
+    pub fn clear(&mut self) {
+        self.subsystems.clear();
+        self.checks = 0;
+        self.last_check_us = 0;
+    }
+
+    pub fn summary(&self) -> HealthSummary {
+        HealthSummary {
+            overall: self.overall(),
+            score: self.score(),
+            subsystem_count: self.subsystems_count(),
+            degraded: self.degraded_subsystems().len(),
+        }
+    }
+
+    fn subsystems_count(&self) -> usize {
+        self.subsystems.len()
+    }
+}
+
+impl Default for HealthMonitor {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct HealthSummary {
+    pub overall: Health,
+    pub score: u8,
+    pub subsystem_count: usize,
+    pub degraded: usize,
+}
+
+impl std::fmt::Display for HealthSummary {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{} (score={}, {} subsystems, {} degraded)",
+            self.overall, self.score, self.subsystem_count, self.degraded
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn new_monitor_healthy() {
+        let m = HealthMonitor::new();
+        assert_eq!(m.overall(), Health::Healthy);
+        assert_eq!(m.score(), 100);
+    }
+
+    #[test]
+    fn report_and_get() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Healthy, "ok", 0));
+        assert!(m.get(Subsystem::Transport).is_some());
+        assert!(m.get(Subsystem::Pipeline).is_none());
+    }
+
+    #[test]
+    fn report_updates_existing() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Pipeline, Health::Healthy, "ok", 0));
+        m.report(SubsystemHealth::new(Subsystem::Pipeline, Health::Degraded, "slow", 100));
+        assert_eq!(m.get(Subsystem::Pipeline).unwrap().health, Health::Degraded);
+        assert_eq!(m.subsystem_count(), 1);
+    }
+
+    #[test]
+    fn overall_takes_minimum() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Healthy, "ok", 0));
+        m.report(SubsystemHealth::new(Subsystem::Pipeline, Health::Degraded, "slow", 0));
+        m.report(SubsystemHealth::new(Subsystem::Memory, Health::Healthy, "ok", 0));
+        assert_eq!(m.overall(), Health::Degraded);
+    }
+
+    #[test]
+    fn score_calculation() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Healthy, "ok", 0));
+        m.report(SubsystemHealth::new(Subsystem::Pipeline, Health::Degraded, "slow", 0));
+        assert_eq!(m.score(), 83);
+    }
+
+    #[test]
+    fn degraded_subsystems() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Healthy, "ok", 0));
+        m.report(SubsystemHealth::new(Subsystem::Pipeline, Health::Unhealthy, "err", 0));
+        let deg = m.degraded_subsystems();
+        assert_eq!(deg.len(), 1);
+        assert_eq!(deg[0].subsystem, Subsystem::Pipeline);
+    }
+
+    #[test]
+    fn check_increments() {
+        let mut m = HealthMonitor::new();
+        m.check(100);
+        m.check(200);
+        assert_eq!(m.checks(), 2);
+        assert_eq!(m.last_check_us(), 200);
+    }
+
+    #[test]
+    fn clear() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Critical, "dead", 0));
+        m.check(100);
+        m.clear();
+        assert_eq!(m.overall(), Health::Healthy);
+        assert_eq!(m.checks(), 0);
+    }
+
+    #[test]
+    fn summary_display() {
+        let mut m = HealthMonitor::new();
+        m.report(SubsystemHealth::new(Subsystem::Transport, Health::Healthy, "ok", 0));
+        let s = m.summary();
+        assert!(s.to_string().contains("healthy"));
+        assert!(s.to_string().contains("100"));
+    }
+
+    #[test]
+    fn health_ordering() {
+        assert!(Health::Critical < Health::Unhealthy);
+        assert!(Health::Unhealthy < Health::Degraded);
+        assert!(Health::Degraded < Health::Healthy);
+    }
+
+    #[test]
+    fn health_display() {
+        assert_eq!(Health::Healthy.to_string(), "healthy");
+        assert_eq!(Health::Critical.to_string(), "critical");
+    }
+
+    #[test]
+    fn subsystem_display() {
+        assert_eq!(Subsystem::Pipeline.to_string(), "pipeline");
+    }
+
+    #[test]
+    fn default_is_new() {
+        let m = HealthMonitor::default();
+        assert_eq!(m.subsystem_count(), 0);
+    }
+}
diff --git a/bootstrap/src/host/mod.rs b/bootstrap/src/host/mod.rs
index 160c1ab9..6130831e 100644
--- a/bootstrap/src/host/mod.rs
+++ b/bootstrap/src/host/mod.rs
@@ -28,6 +28,7 @@ pub mod driver;
 pub mod errors;
 pub mod eventlog;
 pub mod firmware;
+pub mod health;
 pub mod histogram;
 pub mod irq;
 pub mod irqrouter;
@@ -63,6 +64,7 @@ pub use driver::{BitnetDriver, CsrSnapshot, DriverError};
 pub use errors::{by_domain, by_severity, lookup, CatalogEntry, ErrorCode, ErrorDomain, Severity};
 pub use eventlog::{Event, EventKind, EventLog, EventLogStats};
 pub use firmware::{FirmwareHeader, FirmwareImage, ImageError, SectionHeader};
+pub use health::{Health, HealthMonitor, HealthSummary, Subsystem, SubsystemHealth};
 pub use histogram::{Histogram, HistogramSummary};
 pub use irq::{IrqCallback, IrqCounters, IrqDrivenDriver, IrqHandler, IrqSource, ServiceReport};
 pub use irqrouter::{IrqAction, IrqEvent, IrqRouter, IrqSource as RouterIrqSource, RouteError};