fix(jid): treat NULL/empty/"(null)" resource as bare jid

src/database_flatfile_parser.c

@@ -469,7 +469,8 @@ ff_write_line(FILE* fp, const char* timestamp, const char* type, const char* enc
         auto_gchar gchar* safe_to = ff_escape_meta_value(to_jid);
         g_string_append_printf(meta, "|to:%s", safe_to);
     }
-    if (to_resource && strlen(to_resource) > 0) {
+    if (to_resource && strlen(to_resource) > 0
+        && g_strcmp0(to_resource, "(null)") != 0) {
         auto_gchar gchar* safe_tores = ff_escape_meta_value(to_resource);
         g_string_append_printf(meta, "|to_res:%s", safe_tores);
     }
@@ -481,7 +482,8 @@ ff_write_line(FILE* fp, const char* timestamp, const char* type, const char* enc
     // Build sender — escape ": " in the resource part to prevent
     // the parser from splitting at the wrong point.
     GString* sender = g_string_new(from_jid ? from_jid : "unknown");
-    if (from_resource && strlen(from_resource) > 0) {
+    if (from_resource && strlen(from_resource) > 0
+        && g_strcmp0(from_resource, "(null)") != 0) {
         // Escape backslash and colon-space in resource
         GString* safe_res = g_string_sized_new(strlen(from_resource));
         for (const char* p = from_resource; *p; p++) {

src/xmpp/jid.c

@@ -111,6 +111,12 @@ jid_create(const gchar* const str)
 Jid*
 jid_create_from_bare_and_resource(const char* const barejid, const char* const resource)
 {
+    // NULL, empty, or the literal "(null)" (legacy artefact from earlier
+    // builds where g_strdup_printf("%s", NULL) leaked the glibc placeholder
+    // into stored resourceparts) all mean "no resource" — return a bare jid.
+    if (!resource || !*resource || g_strcmp0(resource, "(null)") == 0) {
+        return jid_create(barejid);
+    }
     auto_char char* jid = create_fulljid(barejid, resource);
     return jid_create(jid);
 }