diff --git a/cmd/metis/remote_cmd_test.go b/cmd/metis/remote_cmd_test.go
index 8bcee32..4f70dbb 100644
--- a/cmd/metis/remote_cmd_test.go
+++ b/cmd/metis/remote_cmd_test.go
@@ -1,6 +1,12 @@
 package main
 
-import "testing"
+import (
+	"bytes"
+	"io"
+	"os"
+	"strings"
+	"testing"
+)
 
 func TestOrasPushInvocationUsesRelativeWorkspacePaths(t *testing.T) {
 	dir, args, err := orasPushInvocation("registry.bstein.dev/metis/titan-13:20260331t235724z", "/workspace/build/titan-13.img.xz", "/workspace/build/metadata.json")
@@ -32,3 +38,36 @@ func TestHumanHostPathMapsMountedTmpBackToHostTmp(t *testing.T) {
 		t.Fatalf("expected /tmp/metis-flash-test, got %q", got)
 	}
 }
+
+func TestNewProgressEmitterWritesStructuredMarker(t *testing.T) {
+	origStdout := os.Stdout
+	reader, writer, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("pipe: %v", err)
+	}
+	os.Stdout = writer
+	defer func() {
+		os.Stdout = origStdout
+	}()
+
+	emitter := newProgressEmitter("flash", 92, 98, "Writing the latest image for titan-12", true)
+	emitter(1024, 2048)
+
+	if err := writer.Close(); err != nil {
+		t.Fatalf("close writer: %v", err)
+	}
+	var output bytes.Buffer
+	if _, err := io.Copy(&output, reader); err != nil {
+		t.Fatalf("read progress output: %v", err)
+	}
+	got := output.String()
+	if !strings.Contains(got, "METIS_PROGRESS ") {
+		t.Fatalf("expected structured progress prefix, got %q", got)
+	}
+	if !strings.Contains(got, `"stage":"flash"`) {
+		t.Fatalf("expected flash stage marker, got %q", got)
+	}
+	if !strings.Contains(got, `"written_bytes":1024`) || !strings.Contains(got, `"total_bytes":2048`) {
+		t.Fatalf("expected byte counters in progress marker, got %q", got)
+	}
+}
diff --git a/pkg/service/app_job_test.go b/pkg/service/app_job_test.go
new file mode 100644
index 0000000..fe2cf7d
--- /dev/null
+++ b/pkg/service/app_job_test.go
@@ -0,0 +1,27 @@
+package service
+
+import (
+	"errors"
+	"strings"
+	"testing"
+)
+
+func TestReserveJobRejectsDuplicateActiveNodeJobs(t *testing.T) {
+	app := newTestApp(t)
+	active := app.newJob("replace", "titan-15", "titan-22", "/dev/sdk")
+
+	_, err := app.reserveJob("build", "titan-15", "", "")
+	if err == nil {
+		t.Fatal("expected duplicate job reservation to fail")
+	}
+	var activeErr *activeNodeJobError
+	if !errors.As(err, &activeErr) {
+		t.Fatalf("expected activeNodeJobError, got %T", err)
+	}
+	if activeErr.JobID != active.ID || activeErr.Kind != "replace" {
+		t.Fatalf("unexpected active job conflict: %#v", activeErr)
+	}
+	if !strings.Contains(err.Error(), active.ID) {
+		t.Fatalf("expected error to mention active job id %s, got %q", active.ID, err.Error())
+	}
+}