diff --git a/pkg/model/server.go b/pkg/model/server.go
index 38e296f..c97679a 100644
--- a/pkg/model/server.go
+++ b/pkg/model/server.go
@@ -1,10 +1,59 @@
 package model
 
 import (
+	"encoding/json"
 	"fmt"
 	"time"
 )
 
+// OS labels reported for a server. Renting and reinstalling provision the base
+// OS only, so a machine without Zeabur services is a first-class outcome — it
+// just cannot host Zeabur projects until they are installed.
+const (
+	OSZeaburOS = "ZeaburOS"
+	OSUbuntu   = "Ubuntu"
+)
+
+// serverOS derives the machine's OS from hasK3s.
+//
+// hasK3s is three-state, and the third state is the trap:
+//
+//   - true  — Zeabur services are installed.
+//   - false — explicitly none.
+//   - nil   — a legacy server, which *does* have them. The backend infers this
+//     from the server's certificate data, but the GraphQL field exposes the raw
+//     column, so the inference never reaches the wire.
+//
+// So the test is `== false`, never `!hasK3s`: the latter would sweep every
+// legacy server in and mislabel it as a plain VPS. Mirrors isCleanMachine() in
+// the dashboard.
+//
+// Ubuntu is what Zeabur provisions when renting or reinstalling, so it is
+// accurate for every machine that reached this state through Zeabur. A
+// self-registered server running some other distribution would be labelled
+// Ubuntu too, but such a server has Zeabur services installed at registration
+// and therefore reports ZeaburOS instead.
+func serverOS(hasK3s *bool) string {
+	if hasK3s != nil && !*hasK3s {
+		return OSUbuntu
+	}
+	return OSZeaburOS
+}
+
+// formatUsage renders a used/total pair, or an em dash when the total is zero.
+//
+// Zero total is the contract for "not measured" — a real machine cannot have
+// zero cores, zero memory or zero disk. Printing "0/0" would read as a machine
+// in trouble rather than one whose metrics have not been collected yet.
+// The unit is always spelled out: the backend reports CPU in millicores, so a
+// 4-core machine reads as 4000 and would otherwise look like 4000 cores.
+func formatUsage(used, total int, unit string) string {
+	if total == 0 {
+		return "—"
+	}
+	return fmt.Sprintf("%d/%d %s", used, total, unit)
+}
+
 type Server struct {
 	ID      string  `graphql:"_id"`
 	Country *string `graphql:"country"`
@@ -74,7 +123,7 @@ type ServerDetail struct {
 	Name               string              `graphql:"name"`
 	IP                 string              `graphql:"ip"`
 	SSHPort            int                 `graphql:"sshPort"`
-	SSHUsername         *string             `graphql:"sshUsername"`
+	SSHUsername        *string             `graphql:"sshUsername"`
 	Country            *string             `graphql:"country"`
 	City               *string             `graphql:"city"`
 	Continent          *string             `graphql:"continent"`
@@ -84,6 +133,18 @@ type ServerDetail struct {
 	Status             ServerStatus        `graphql:"status"`
 	ProviderInfo       *ServerProviderInfo `graphql:"providerInfo"`
 	Events             []ServerEvent       `graphql:"events"`
+	HasK3s             *bool               `graphql:"hasK3s"`
+}
+
+// MarshalJSON adds the derived `os` field so machine-readable output states the
+// machine's kind outright, instead of leaving every caller to rediscover that
+// hasK3s is three-state.
+func (s ServerDetail) MarshalJSON() ([]byte, error) {
+	type alias ServerDetail
+	return json.Marshal(struct {
+		alias
+		OS string `json:"os"`
+	}{alias(s), serverOS(s.HasK3s)})
 }
 
 type ServerProviderInfo struct {
@@ -98,7 +159,7 @@ type ServerEvent struct {
 }
 
 func (s *ServerDetail) Header() []string {
-	return []string{"ID", "Name", "IP", "Provider", "Location", "Status", "VM Status", "CPU", "Memory", "Disk", "Managed", "Created At"}
+	return []string{"ID", "Name", "IP", "Provider", "Location", "Status", "VM Status", "OS", "CPU", "Memory", "Disk", "Managed", "Created At"}
 }
 
 func (s *ServerDetail) Rows() [][]string {
@@ -126,9 +187,9 @@ func (s *ServerDetail) Rows() [][]string {
 		managed = "Yes"
 	}
 
-	cpu := fmt.Sprintf("%d/%d", s.Status.UsedCPU, s.Status.TotalCPU)
-	memory := fmt.Sprintf("%d/%d MB", s.Status.UsedMemory, s.Status.TotalMemory)
-	disk := fmt.Sprintf("%d/%d MB", s.Status.UsedDisk, s.Status.TotalDisk)
+	cpu := formatUsage(s.Status.UsedCPU, s.Status.TotalCPU, "m")
+	memory := formatUsage(s.Status.UsedMemory, s.Status.TotalMemory, "MB")
+	disk := formatUsage(s.Status.UsedDisk, s.Status.TotalDisk, "MB")
 
 	return [][]string{
 		{
@@ -139,6 +200,7 @@ func (s *ServerDetail) Rows() [][]string {
 			location,
 			status,
 			s.Status.VMStatus,
+			serverOS(s.HasK3s),
 			cpu,
 			memory,
 			disk,
@@ -217,12 +279,22 @@ type ServerListItem struct {
 	ProvisioningStatus *string             `graphql:"provisioningStatus"`
 	Status             ServerStatus        `graphql:"status"`
 	ProviderInfo       *ServerProviderInfo `graphql:"providerInfo"`
+	HasK3s             *bool               `graphql:"hasK3s"`
+}
+
+// MarshalJSON adds the derived `os` field. See ServerDetail.MarshalJSON.
+func (s ServerListItem) MarshalJSON() ([]byte, error) {
+	type alias ServerListItem
+	return json.Marshal(struct {
+		alias
+		OS string `json:"os"`
+	}{alias(s), serverOS(s.HasK3s)})
 }
 
 type ServerListItems []ServerListItem
 
 func (s ServerListItems) Header() []string {
-	return []string{"ID", "Name", "IP", "Provider", "Location", "Status", "VM Status"}
+	return []string{"ID", "Name", "IP", "Provider", "Location", "Status", "VM Status", "OS"}
 }
 
 func (s ServerListItems) Rows() [][]string {
@@ -255,6 +327,7 @@ func (s ServerListItems) Rows() [][]string {
 			location,
 			status,
 			item.Status.VMStatus,
+			serverOS(item.HasK3s),
 		}
 	}
 	return rows
diff --git a/pkg/model/server_test.go b/pkg/model/server_test.go
new file mode 100644
index 0000000..5bba111
--- /dev/null
+++ b/pkg/model/server_test.go
@@ -0,0 +1,128 @@
+package model_test
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/zeabur/cli/pkg/model"
+)
+
+func ptr[T any](v T) *T { return &v }
+
+// indexOf returns the column index of name in header, failing the test when the
+// column is missing — keeps the assertions below readable and order-independent.
+func indexOf(t *testing.T, header []string, name string) int {
+	t.Helper()
+	for i, h := range header {
+		if h == name {
+			return i
+		}
+	}
+	t.Fatalf("column %q not found in header %v", name, header)
+	return -1
+}
+
+func TestServerListItemsOSColumn(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name   string
+		hasK3s *bool
+		want   string
+	}{
+		{name: "k3s installed", hasK3s: ptr(true), want: "ZeaburOS"},
+		{name: "explicitly no k3s", hasK3s: ptr(false), want: "Ubuntu"},
+		// A legacy server predates the field and does have Zeabur services; the
+		// backend infers that from certificate data but exposes the raw column,
+		// so null must never be read as "no k3s".
+		{name: "legacy server reports null", hasK3s: nil, want: "ZeaburOS"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			items := model.ServerListItems{{ID: "abc", Name: "s", HasK3s: tt.hasK3s}}
+			rows := items.Rows()
+			require.Len(t, rows, 1)
+			assert.Equal(t, tt.want, rows[0][indexOf(t, items.Header(), "OS")])
+		})
+	}
+}
+
+func TestServerDetailOSColumn(t *testing.T) {
+	t.Parallel()
+
+	server := &model.ServerDetail{ID: "abc", Name: "s", HasK3s: ptr(false)}
+	rows := server.Rows()
+	require.Len(t, rows, 1)
+	assert.Equal(t, "Ubuntu", rows[0][indexOf(t, server.Header(), "OS")])
+}
+
+func TestServerDetailResourceColumns(t *testing.T) {
+	t.Parallel()
+
+	t.Run("renders usage when measured", func(t *testing.T) {
+		t.Parallel()
+
+		server := &model.ServerDetail{
+			Status: model.ServerStatus{
+				UsedCPU: 1000, TotalCPU: 4000,
+				UsedMemory: 512, TotalMemory: 2048,
+				UsedDisk: 3000, TotalDisk: 40000,
+			},
+		}
+		row := server.Rows()[0]
+		header := server.Header()
+		// CPU is millicores, so the unit must be spelled out — a 4-core machine
+		// reports 4000 and would otherwise read as 4000 cores.
+		assert.Equal(t, "1000/4000 m", row[indexOf(t, header, "CPU")])
+		assert.Equal(t, "512/2048 MB", row[indexOf(t, header, "Memory")])
+		assert.Equal(t, "3000/40000 MB", row[indexOf(t, header, "Disk")])
+	})
+
+	// A real machine cannot have zero cores, so a zero total means the metrics
+	// were never collected. Printing "0/0" would read as a machine in trouble.
+	t.Run("renders a dash when not measured", func(t *testing.T) {
+		t.Parallel()
+
+		server := &model.ServerDetail{}
+		row := server.Rows()[0]
+		header := server.Header()
+		assert.Equal(t, "—", row[indexOf(t, header, "CPU")])
+		assert.Equal(t, "—", row[indexOf(t, header, "Memory")])
+		assert.Equal(t, "—", row[indexOf(t, header, "Disk")])
+	})
+}
+
+func TestServerJSONCarriesOS(t *testing.T) {
+	t.Parallel()
+
+	t.Run("detail", func(t *testing.T) {
+		t.Parallel()
+
+		data, err := json.Marshal(&model.ServerDetail{ID: "abc", HasK3s: ptr(false)})
+		require.NoError(t, err)
+
+		var got map[string]any
+		require.NoError(t, json.Unmarshal(data, &got))
+		assert.Equal(t, "Ubuntu", got["os"])
+		assert.Equal(t, "abc", got["ID"])
+		// The raw three-state field stays available for callers that need it.
+		assert.Equal(t, false, got["HasK3s"])
+	})
+
+	t.Run("list", func(t *testing.T) {
+		t.Parallel()
+
+		data, err := json.Marshal(model.ServerListItems{{ID: "abc", HasK3s: ptr(true)}})
+		require.NoError(t, err)
+
+		var got []map[string]any
+		require.NoError(t, json.Unmarshal(data, &got))
+		require.Len(t, got, 1)
+		assert.Equal(t, "ZeaburOS", got[0]["os"])
+	})
+}