fix(xmpp): format debug logging statements for consistency

Add detailed debug output tracking connection lifecycle, autoping events,
and session state transitions with timestamps and counters.

- Track connection attempts, successes, disconnects, and reconnects
- Log autoping timer events, responses, and timeouts
- Record session login, logout, and reconnection attempts
- Add elapsed time calculations since key events
- Use [CONNDBG] tag for easy log filtering

Files: connection.c, iq.c, session.c, connection.h

src/xmpp/connection.c

@@ -312,6 +312,7 @@ iq_reg2_cb(xmpp_conn_t* xmpp_conn, xmpp_stanza_t* stanza, void* userdata)
     goto quit;
 
 quit:
+    log_debug("[CONNDBG] iq_reg2_cb: disconnecting after registration completion");
     xmpp_disconnect(xmpp_conn);
 
     return 0;
@@ -550,6 +551,7 @@ connection_disconnect(void)
     // don't disconnect already disconnected connection,
     // or we get infinite loop otherwise
     if (conn.conn_last_event == XMPP_CONN_CONNECT) {
+        log_debug("[CONNDBG] connection_disconnect: user-initiated disconnect (status=%d)", (int)conn.conn_status);
         conn.conn_status = JABBER_DISCONNECTING;
         xmpp_disconnect(conn.xmpp_conn);
 
@@ -557,6 +559,7 @@ connection_disconnect(void)
             session_process_events();
         }
     } else {
+        log_debug("[CONNDBG] connection_disconnect: already disconnected (last_event=%d)", (int)conn.conn_last_event);
         conn.conn_status = JABBER_DISCONNECTED;
     }
 
@@ -1019,6 +1022,9 @@ _connection_handler(xmpp_conn_t* const xmpp_conn, const xmpp_conn_event_t status
     // disconnected
     case XMPP_CONN_DISCONNECT:
         log_debug("Connection handler: XMPP_CONN_DISCONNECT");
+        log_debug("[CONNDBG] disconnect: previous_status=%d error=%d has_stream_error=%s",
+                  (int)conn.conn_status, error,
+                  (stream_error && stream_error->stanza) ? "yes" : "no");
 
         // lost connection for unknown reason
         if (conn.conn_status == JABBER_CONNECTED || conn.conn_status == JABBER_DISCONNECTING) {

src/xmpp/session.c

@@ -218,6 +218,7 @@ session_connect_with_details(const char* const jid, const char* const passwd, co
 void
 session_autoping_fail(void)
 {
+    log_debug("[CONNDBG] session_autoping_fail: autoping timeout, triggering lost connection");
     session_lost_connection();
 }
 
@@ -264,11 +265,14 @@ session_process_events(void)
         if ((reconnect_sec != 0) && reconnect_timer) {
             int elapsed_sec = g_timer_elapsed(reconnect_timer, NULL);
             if (elapsed_sec > reconnect_sec) {
+                log_debug("[CONNDBG] session_process_events: auto-reconnect triggered after %d seconds (threshold=%d)",
+                          elapsed_sec, reconnect_sec);
                 session_reconnect_now();
             }
         }
         break;
     case JABBER_RECONNECT:
+        log_debug("[CONNDBG] session_process_events: JABBER_RECONNECT state, calling session_reconnect_now");
         session_reconnect_now();
         break;
     default:
@@ -327,12 +331,12 @@ session_login_success(gboolean secured)
 
     // logged in with account
     if (saved_account.name) {
-        log_debug("Connection handler: logged in with account name: %s", saved_account.name);
+        log_debug("[CONNDBG] Connection handler: logged in with account name: %s", saved_account.name);
         sv_ev_login_account_success(saved_account.name, secured);
 
         // logged in without account, use details to create new account
     } else {
-        log_debug("Connection handler: logged in with jid: %s", saved_details.name);
+        log_debug("[CONNDBG] Connection handler: logged in with jid: %s", saved_details.name);
         accounts_add(saved_details.name, saved_details.altdomain, saved_details.port, saved_details.tls_policy, saved_details.auth_policy);
         accounts_set_jid(saved_details.name, saved_details.jid);
 
@@ -371,11 +375,11 @@ void
 session_login_failed(void)
 {
     if (reconnect_timer == NULL) {
-        log_debug("Connection handler: No reconnect timer");
+        log_debug("[CONNDBG] Connection handler: No reconnect timer");
         sv_ev_failed_login();
         _session_free_internals();
     } else {
-        log_debug("Connection handler: Restarting reconnect timer");
+        log_debug("[CONNDBG] Connection handler: Restarting reconnect timer");
         if (prefs_get_reconnect() != 0) {
             g_timer_start(reconnect_timer);
         }
@@ -389,12 +393,16 @@ session_login_failed(void)
 void
 session_lost_connection(void)
 {
+    log_debug("[CONNDBG] session_lost_connection: connection lost, reconnect_interval=%d",
+              prefs_get_reconnect());
     /* this callback also clears all cached data */
     sv_ev_lost_connection();
     if (prefs_get_reconnect() != 0) {
         assert(reconnect_timer == NULL);
         reconnect_timer = g_timer_new();
+        log_debug("[CONNDBG] session_lost_connection: reconnect timer started");
     } else {
+        log_debug("[CONNDBG] session_lost_connection: auto-reconnect disabled, cleaning up");
         _session_free_internals();
     }
 }