Add local and NetBox server notes and improve reliability

internal/cache/cache.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"encoding/json"
+	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/storage"
 	"os"
 	"path/filepath"
 	"sort"
@@ -116,12 +117,15 @@ func (c *Cache) Save() error {
 	if err != nil {
 		return err
 	}
-	return os.WriteFile(c.path, data, 0o644)
+	return storage.WriteFile(c.path, data, 0o600)
 }
 
 func (c *Cache) Upsert(e Entry) {
 	e.CachedAt = time.Now()
 	c.mu.Lock()
+	if old, ok := c.entries[e.Name]; ok && e.LastUsed.IsZero() {
+		e.LastUsed = old.LastUsed
+	}
 	c.entries[e.Name] = e
 	c.mu.Unlock()
 }

internal/cache/cache_test.go

@@ -471,3 +471,15 @@ func tempFile(t *testing.T, content []byte) string {
 	f.Close()
 	return f.Name()
 }
+
+func TestUpsertPreservesUsageHistory(t *testing.T) {
+	c := New("", 3600)
+	c.Upsert(Entry{Name: "web01", IP: "10.0.0.1"})
+	c.MarkUsed("web01")
+	before, _ := c.Get("web01")
+	c.Upsert(Entry{Name: "web01", IP: "10.0.0.2"})
+	after, _ := c.Get("web01")
+	if after.LastUsed != before.LastUsed || after.IP != "10.0.0.2" {
+		t.Fatalf("history lost: %+v", after)
+	}
+}