Keep one reading when two paths are measured at one moment, rather than failing the machine's record (hq issue 368 review)

internal/inventory/data.go

@@ -195,7 +195,8 @@ func (i *Inventory) RecordData(ctx context.Context, machine string, declared []D
 				 where d.machine = $1 and d.module = $2 and d.item = $3
 				   and not exists (select 1 from data_reading
 				                    where machine = $1 and module = $2 and item = $3 and path = d.path
-				                      and at > $4::timestamptz - $7::interval)`,
+				                      and at > $4::timestamptz - $7::interval)
+				on conflict (machine, module, item, at) do nothing`,
 				machine, d.Module, d.Item, *m.MeasuredAt, *m.Size, m.LastWrite,
 				fmt.Sprintf("%d seconds", int(readingEvery.Seconds()))); err != nil {
 				return change, err

internal/inventory/data_test.go

@@ -172,3 +172,22 @@ func TestThePeakIsReadAtTheItemsPathOnly(t *testing.T) {
 		t.Fatalf("back at the first path the peak is %v (%v), want 94700000", peaks, err)
 	}
 }
+
+// Two measurements at the same moment at two paths keep one reading and fail nothing: the second
+// would otherwise break the reading's key and lose the machine's whole record (issue 368 review).
+func TestTwoPathsAtOneMomentFailNothing(t *testing.T) {
+	inv := fresh(t)
+	ctx := t.Context()
+	now := time.Date(2026, 10, 10, 0, 0, 0, 0, time.UTC)
+	declared := []DeclaredData{{Module: "claude-code", Item: "agent-home", Class: "valuable", Owned: true}}
+	for _, path := range []string{"/home/operator/.claude", "/home/agent/.claude"} {
+		if _, err := inv.RecordData(ctx, "novox", declared, map[string]map[string]Measurement{"claude-code": {
+			"agent-home": {Path: path, Size: size(100), MeasuredAt: at(now)}}}, "", now); err != nil {
+			t.Fatalf("a measurement at %s failed: %v", path, err)
+		}
+	}
+	r, err := inv.DataOf(ctx, "novox", "claude-code", "agent-home")
+	if err != nil || r.Path != "/home/agent/.claude" {
+		t.Fatalf("%+v, %v", r, err)
+	}
+}