Show what a machine said it is made of in node, with its age (issue 160)

The architecture and kernel a machine reported were kept and read by nothing, and the facts the
node-engine now says (memory, filesystems, processor, distribution, virtual or physical, uptime,
timezone) would have joined them. node shows every one in one block with the age of the account,
and a fact the machine could not determine as unknown with its why, never as a zero.

cmd/mesh-controller/machine_lines_test.go

@@ -0,0 +1,80 @@
+package main
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/inventory"
+)
+
+// Defends novox/hq issue 160: `node` shows every fact a machine said it is made of, in one block with its
+// age, the architecture and kernel among them; and a fact it could not determine as unknown with why.
+func TestNodeShowsWhatAMachineIsMadeOfWithItsAge(t *testing.T) {
+	now := time.Date(2026, 10, 12, 15, 0, 0, 0, time.UTC)
+	booted := now.Add(-75 * time.Hour)
+	a := inventory.MachineAccount{Architecture: "amd64", Kernel: "linux", Machine: &inventory.MadeOf{
+		ObservedAt: now.Add(-3 * time.Hour), KernelRelease: "7.2.8-arch1-2", Distribution: "Arch Linux",
+		Version: "rolling", Processor: "AMD Ryzen 9 8945HS", Cores: 8, Threads: 16, MemoryBytes: 32891494400,
+		Virtual: "physical", BootedAt: &booted, Timezone: "Europe/Brussels",
+		Filesystems: []inventory.MountedFilesystem{{Mount: "/", Device: "/dev/nvme0n1p3", Type: "ext4",
+			SizeBytes: 987978522624, FreeBytes: 31830110208}},
+		Unknown: map[string]string{"public address": "how it learns it is not decided yet"},
+	}}
+	got := strings.Join(machineLines(a, true, now), "\n")
+	t.Log("\n" + got)
+	for _, want := range []string{
+		"what it is made of, as it said 3h ago:",
+		"architecture    amd64",
+		"kernel          linux 7.2.8-arch1-2",
+		"distribution    Arch Linux rolling",
+		"processor       AMD Ryzen 9 8945HS",
+		"cores           8",
+		"threads         16",
+		"memory          30.6 GiB",
+		"virtual         physical",
+		"up              3d, since",
+		"timezone        Europe/Brussels",
+		"filesystems     /  920.1 GiB, 29.6 GiB free (ext4 /dev/nvme0n1p3)",
+		"public address  unknown: how it learns it is not decided yet",
+	} {
+		if !strings.Contains(got, want) {
+			t.Errorf("missing %q", want)
+		}
+	}
+}
+
+func TestAFactAMachineCouldNotReadIsShownUnknownNeverZero(t *testing.T) {
+	now := time.Date(2026, 10, 12, 15, 0, 0, 0, time.UTC)
+	a := inventory.MachineAccount{Architecture: "arm64", Kernel: "linux", Machine: &inventory.MadeOf{
+		ObservedAt: now, Unknown: map[string]string{"memory": "MemTotal not found in /proc/meminfo",
+			"cores": "/proc/cpuinfo says no core id", "kernel release": "permission denied"}}}
+	got := strings.Join(machineLines(a, true, now), "\n")
+	t.Log("\n" + got)
+	for _, want := range []string{
+		"memory          unknown: MemTotal not found in /proc/meminfo",
+		"cores           unknown: /proc/cpuinfo says no core id",
+		"kernel          linux (release unknown: permission denied)",
+		// Neither said nor named unknown: the node-engine broke its rule, and that is shown.
+		"timezone        unknown: the machine said neither it nor why",
+	} {
+		if !strings.Contains(got, want) {
+			t.Errorf("missing %q", want)
+		}
+	}
+	if strings.Contains(got, " 0 ") || strings.Contains(got, "0 B") {
+		t.Error("a fact the machine could not read was shown as a zero")
+	}
+}
+
+func TestAnOlderNodeEngineStillShowsArchitectureAndKernel(t *testing.T) {
+	got := strings.Join(machineLines(inventory.MachineAccount{Architecture: "amd64", Kernel: "linux"}, true,
+		time.Now()), "\n")
+	if !strings.Contains(got, "older than the one that says it") || !strings.Contains(got, "architecture    amd64") ||
+		!strings.Contains(got, "kernel          linux") {
+		t.Errorf("%s", got)
+	}
+	if got := strings.Join(machineLines(inventory.MachineAccount{}, false, time.Now()), "\n"); !strings.Contains(got, "never said") {
+		t.Errorf("%s", got)
+	}
+}