feat(server): graceful scheduler shutdown, /healthz, healthcheck mode

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwxdSt4reTm7Dj1oxRvpP3

cmd/server/main_test.go

@@ -1,6 +1,10 @@
 package main
 
-import "testing"
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
 
 func TestIsAPIPath(t *testing.T) {
 	cases := []struct {
@@ -20,3 +24,68 @@ func TestIsAPIPath(t *testing.T) {
 		}
 	}
 }
+
+func TestBuildMux(t *testing.T) {
+	var metricsHit, apiHit, webHit bool
+
+	metricsHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		metricsHit = true
+		w.WriteHeader(http.StatusOK)
+	})
+	apiRouter := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		apiHit = true
+		w.WriteHeader(http.StatusOK)
+	})
+	webHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		webHit = true
+		w.WriteHeader(http.StatusOK)
+	})
+
+	mux := buildMux(metricsHandler, apiRouter, webHandler)
+
+	t.Run("healthz returns 200 ok", func(t *testing.T) {
+		metricsHit, apiHit, webHit = false, false, false
+		rr := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/healthz", nil)
+		mux.ServeHTTP(rr, req)
+		if rr.Code != http.StatusOK {
+			t.Fatalf("status = %d, want %d", rr.Code, http.StatusOK)
+		}
+		if rr.Body.String() != "ok" {
+			t.Fatalf("body = %q, want %q", rr.Body.String(), "ok")
+		}
+		if metricsHit || apiHit || webHit {
+			t.Fatalf("healthz must not fall through to other handlers")
+		}
+	})
+
+	t.Run("metrics routed to metrics handler", func(t *testing.T) {
+		metricsHit, apiHit, webHit = false, false, false
+		rr := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/metrics", nil)
+		mux.ServeHTTP(rr, req)
+		if !metricsHit {
+			t.Fatalf("expected metrics handler to be hit")
+		}
+	})
+
+	t.Run("api path routed to api router", func(t *testing.T) {
+		metricsHit, apiHit, webHit = false, false, false
+		rr := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/api/domains", nil)
+		mux.ServeHTTP(rr, req)
+		if !apiHit {
+			t.Fatalf("expected api router to be hit")
+		}
+	})
+
+	t.Run("other path routed to web handler", func(t *testing.T) {
+		metricsHit, apiHit, webHit = false, false, false
+		rr := httptest.NewRecorder()
+		req := httptest.NewRequest(http.MethodGet, "/domains/xyz", nil)
+		mux.ServeHTTP(rr, req)
+		if !webHit {
+			t.Fatalf("expected web handler to be hit")
+		}
+	})
+}