Add HTTP health endpoint on /health and /api/mirror-health

- New axum-based health server on port 7335 (configurable via health_port)
- Reports status, uptime, cycle_count, last_cycle_ok as JSON
- Status is 'ok' on startup and after successful cycles, 'degraded' after failures
- Config: storage.health_port defaults to 7335
- Spawned alongside daemon loop, independent of mirror cycles

1 files changed, 40 insertions, 0 deletions

diff --git a/src/http_health.rs b/src/http_health.rs
new file mode 100644
index 0000000..0cdfeb5
--- /dev/null
+++ b/src/http_health.rs
@@ -0,0 +1,40 @@
+use axum::extract::State;
+use axum::response::Json;
+use axum::routing::get;
+use axum::Router;
+use serde_json::{json, Value};
+use std::sync::Arc;
+use std::time::Instant;
+use tokio::sync::watch;
+
+pub struct HealthState {
+    pub started_at: Instant,
+    pub cycle_count: watch::Receiver<u64>,
+    pub last_cycle_ok: watch::Receiver<bool>,
+    pub db_path: String,
+}
+
+pub async fn start_health_server(port: u16, state: Arc<HealthState>) -> anyhow::Result<()> {
+    let app = Router::new()
+        .route("/health", get(health_handler))
+        .route("/api/mirror-health", get(health_handler))
+        .with_state(state);
+
+    let listener = tokio::net::TcpListener::bind(format!("127.0.0.1:{}", port)).await?;
+    tracing::info!(port, "health server listening");
+    axum::serve(listener, app).await?;
+    Ok(())
+}
+
+async fn health_handler(State(state): State<Arc<HealthState>>) -> Json<Value> {
+    let uptime = state.started_at.elapsed();
+    let cycle_count = *state.cycle_count.borrow();
+    let last_ok = *state.last_cycle_ok.borrow();
+
+    Json(json!({
+        "status": if last_ok || cycle_count == 0 { "ok" } else { "degraded" },
+        "uptime_secs": uptime.as_secs(),
+        "cycle_count": cycle_count,
+        "last_cycle_ok": last_ok,
+    }))
+}