docs: update all docs for :last, :search, :mute-joins and MOTD

- README: add new commands to COMMAND mode table, MOTD section,
  update Known Limitations (100-msg limit now softened by :last/:search)
- tnt.1: add :last/:search/:mute-joins to man page command table,
  add motd.txt to FILES section
- CHANGELOG: add 2026-04-23 entry
- QUICKREF: rewrite command section, add new commands, add motd.txt to files
- ROADMAP: mark Stage 4 :last/:search/:mute-joins items as completed
- DEPLOYMENT: add MOTD setup section

README.md

@@ -82,6 +82,9 @@ Ctrl+C     - Exit chat
 :nick <name>         - Change nickname
 :msg <user> <text>   - Whisper to user
 :w <user> <text>     - Short alias for :msg
+:last [N]            - Show last N messages from history (max 50, default 10)
+:search <keyword>    - Search full message history (case-insensitive)
+:mute-joins          - Toggle join/leave system notifications
 :help                - Show available commands
 :clear               - Clear command output
 :q, :quit, :exit     - Disconnect
@@ -276,9 +279,24 @@ See [docs/DEPLOYMENT.md](docs/DEPLOYMENT.md) for details.
 ```
 messages.log    - Chat history (RFC3339 format)
 host_key        - SSH host key (auto-generated, 4096-bit RSA)
+motd.txt        - Message of the Day (optional, shown to users on connect)
 tnt.service     - systemd service unit
 ```
 
+### MOTD (Message of the Day)
+
+Place a `motd.txt` file in the state directory to show a welcome message to every user on connect. Users see the MOTD before entering the chat and press any key to continue.
+
+```sh
+# Example (assuming default state dir)
+cat > motd.txt <<'EOF'
+Welcome to the chat server!
+Be respectful. No spam.
+EOF
+```
+
+Delete `motd.txt` to disable the MOTD.
+
 ## Documentation
 
 - [Development Guide](https://github.com/m1ngsama/TNT/wiki/Development-Guide) - Complete development manual
@@ -300,7 +318,7 @@ tnt.service     - systemd service unit
 ## Known Limitations
 
 - Single chat room (no multi-room support yet)
-- Keeps only last 100 messages in memory
+- TUI displays at most 100 messages at once; use `:last N` or `:search` to access older history from disk
 - Ctrl+W only recognizes ASCII space as word boundary
 
 ## Contributing

docs/CHANGELOG.md

@@ -1,5 +1,15 @@
 # Changelog
 
+## 2026-04-23 - Chat UX Commands and MOTD
+
+### Added
+- **`:last [N]`** — show last N messages retrieved directly from the log file (1–50, default 10), bypassing the 100-message in-memory ring buffer limit
+- **`:search <keyword>`** — case-insensitive full-text search across the entire message history on disk; returns the most recent 15 matches
+- **`:mute-joins`** — per-client toggle to silence join/leave system notifications; title bar shows `[静音]` when active
+- **MOTD support** — place `motd.txt` in the state directory; users see it on connect and press any key to enter chat
+- **`message_search()`** — new function in `message.c` / `message.h` for log file keyword search with rolling result collection
+- Updated in-TUI help screens (English and Chinese) with new commands
+
 ## 2026-03-10 - SSH Runtime & Unix Interface Update
 
 ### Fixed

docs/DEPLOYMENT.md

@@ -89,6 +89,24 @@ Recommended interpretation:
 - `TNT_MAX_CONN_RATE_PER_IP`: new connection attempts allowed per IP per 60 seconds
 - `TNT_RATE_LIMIT=0`: disables rate-based blocking and auth-failure IP blocking, but not the explicit capacity limits
 
+## MOTD (Message of the Day)
+
+Place a `motd.txt` file in the state directory. TNT displays it to each user on connect; they press any key to enter the chat.
+
+```bash
+# Systemd deployment (state dir is /var/lib/tnt)
+sudo tee /var/lib/tnt/motd.txt <<'EOF'
+Welcome! Be respectful. No spam.
+Type :help for available commands.
+EOF
+sudo chown tnt:tnt /var/lib/tnt/motd.txt
+
+# Remove to disable
+sudo rm /var/lib/tnt/motd.txt
+```
+
+No restart required — TNT reads the file on each new connection.
+
 ## Firewall
 
 ```bash

docs/QUICKREF.md

@@ -17,21 +17,37 @@ DEBUG
   valgrind --leak-check=full ./tnt
   make check
 
+COMMANDS (COMMAND mode, prefix with :)
+  list, users, who       show online users
+  nick <name>            change nickname
+  msg <user> <text>      whisper to user
+  w <user> <text>        alias for msg
+  last [N]               last N messages from log (default 10, max 50)
+  search <keyword>       search full history (case-insensitive, 15 results)
+  mute-joins             toggle join/leave notifications
+  help                   show all commands
+  clear                  clear output
+  q / quit / exit        disconnect
+
+INSERT MODE
+  /me <action>           action message
+  @username              mention (bell + highlight)
+
 STRUCTURE
   src/main.c          entry, signals
-  src/ssh_server.c    SSH, threads
+  src/ssh_server.c    SSH, threads, commands
   src/chat_room.c     broadcast
-  src/message.c       persistence
-  src/tui.c           rendering
+  src/message.c       persistence, search
+  src/tui.c           rendering, help
   src/utf8.c          unicode
 
 LIMITS
-  64 clients max
-  100 messages in RAM
+  64 clients max (configurable)
+  100 messages in RAM; unlimited on disk
   1024 bytes/message
 
 FILES
-  HACKING           dev guide
-  CHANGELOG.md      changes
-  messages.log      chat log
-  host_key          SSH key
+  messages.log      chat log (RFC3339)
+  host_key          SSH key (auto-generated)
+  motd.txt          message of the day (optional)
+  CHANGELOG.md      version history

docs/ROADMAP.md

@@ -59,11 +59,11 @@ Goal: keep the interface efficient for terminal users without sacrificing simpli
 - keep the current modal editing model, but make its behavior precise and documented
 - support resize, cursor movement, command history, and predictable paste behavior
 - add useful chat commands with clear semantics:
-  - `/nick`
-  - `/me`
-  - `/last N`
-  - `/search`
-  - `/mute-joins`
+  - ✅ `:nick` / `:name` — nickname change with broadcast
+  - ✅ `/me` — action messages
+  - ✅ `:last N` — show last N messages from disk history
+  - ✅ `:search <keyword>` — case-insensitive full-text search
+  - ✅ `:mute-joins` — per-client join/leave notification toggle
 - improve discoverability of NORMAL and COMMAND mode actions
 - make status lines and help output concise enough for small terminals
 

include/message.h

@@ -22,4 +22,8 @@ int message_save(const message_t *msg);
 /* Format a message for display */
 void message_format(const message_t *msg, char *buffer, size_t buf_size, int width);
 
+/* Search log file for messages matching query (case-insensitive, username or content).
+ * Returns the last max_results matches in chronological order; caller must free *results. */
+int message_search(const char *query, message_t **results, int max_results);
+
 #endif /* MESSAGE_H */

include/ssh_server.h

@@ -30,6 +30,7 @@ typedef struct client {
     time_t connect_time;
     time_t last_active;
     atomic_bool redraw_pending;
+    bool mute_joins;
     pthread_t thread;
     atomic_bool connected;
     int ref_count;                   /* Reference count for safe cleanup */

src/message.c

@@ -244,6 +244,78 @@ int message_save(const message_t *msg) {
     return rc;
 }
 
+/* Search log file for messages whose username or content contains query.
+ * Case-insensitive. Returns the last max_results matches (most recent); caller frees *results. */
+int message_search(const char *query, message_t **results, int max_results) {
+    char log_path[PATH_MAX];
+
+    message_t *res = calloc(max_results, sizeof(message_t));
+    if (!res) return 0;
+
+    if (!query || query[0] == '\0' ||
+        tnt_state_path(log_path, sizeof(log_path), LOG_FILE) < 0) {
+        *results = res;
+        return 0;
+    }
+
+    pthread_mutex_lock(&g_message_file_lock);
+    FILE *fp = fopen(log_path, "r");
+    if (!fp) {
+        pthread_mutex_unlock(&g_message_file_lock);
+        *results = res;
+        return 0;
+    }
+
+    char line[2048];
+    int count = 0;
+
+    while (fgets(line, sizeof(line), fp)) {
+        size_t line_len = strlen(line);
+        if (line_len >= sizeof(line) - 1) {
+            int c;
+            while ((c = fgetc(fp)) != '\n' && c != EOF);
+            continue;
+        }
+
+        char line_copy[2048];
+        strncpy(line_copy, line, sizeof(line_copy) - 1);
+        line_copy[sizeof(line_copy) - 1] = '\0';
+
+        char *timestamp_str = strtok(line_copy, "|");
+        char *username = strtok(NULL, "|");
+        char *content = strtok(NULL, "\n");
+
+        if (!timestamp_str || !username || !content || username[0] == '\0') continue;
+        if (strlen(username) >= MAX_USERNAME_LEN || strlen(content) >= MAX_MESSAGE_LEN) continue;
+        if (!utf8_is_valid_string(username) || !utf8_is_valid_string(content)) continue;
+
+        if (strcasestr(username, query) == NULL && strcasestr(content, query) == NULL) continue;
+
+        time_t msg_time = parse_rfc3339_utc(timestamp_str);
+        if (msg_time == (time_t)-1) continue;
+
+        message_t m;
+        m.timestamp = msg_time;
+        strncpy(m.username, username, MAX_USERNAME_LEN - 1);
+        m.username[MAX_USERNAME_LEN - 1] = '\0';
+        strncpy(m.content, content, MAX_MESSAGE_LEN - 1);
+        m.content[MAX_MESSAGE_LEN - 1] = '\0';
+
+        if (count < max_results) {
+            res[count++] = m;
+        } else {
+            memmove(&res[0], &res[1], (max_results - 1) * sizeof(message_t));
+            res[max_results - 1] = m;
+            /* count stays at max_results */
+        }
+    }
+
+    fclose(fp);
+    pthread_mutex_unlock(&g_message_file_lock);
+    *results = res;
+    return (count < max_results) ? count : max_results;
+}
+
 /* Format a message for display */
 void message_format(const message_t *msg, char *buffer, size_t buf_size, int width) {
     struct tm tm_info;

src/ssh_server.c

@@ -1198,6 +1198,9 @@ static void execute_command(client_t *client) {
                        "list, users, who    - Show online users\n"
                        "nick/name <name>    - Change nickname\n"
                        "msg/w <user> <text> - Whisper to user\n"
+                       "last [N]            - Show last N messages\n"
+                       "search <keyword>    - Search message history\n"
+                       "mute-joins          - Toggle join/leave notices\n"
                        "help, commands      - Show this help\n"
                        "clear, cls          - Clear command output\n"
                        "q, quit, exit       - Disconnect\n"
@@ -1289,6 +1292,63 @@ static void execute_command(client_t *client) {
                            "Nickname changed: %s -> %s\n", old_name, client->username);
         }
 
+    } else if (strncmp(cmd, "last", 4) == 0 && (cmd[4] == ' ' || cmd[4] == '\0')) {
+        char *arg = cmd + 4;
+        while (*arg == ' ') arg++;
+        int n = 10;
+        if (*arg != '\0') {
+            char *endp;
+            long val = strtol(arg, &endp, 10);
+            if (*endp != '\0' || val < 1 || val > 50) {
+                buffer_appendf(output, sizeof(output), &pos,
+                               "Usage: last [N]  (N: 1-50, default 10)\n");
+                goto cmd_done;
+            }
+            n = (int)val;
+        }
+
+        message_t *last_msgs = NULL;
+        int last_count = message_load(&last_msgs, n);
+        buffer_appendf(output, sizeof(output), &pos,
+                       "--- Last %d message(s) ---\n", last_count);
+        for (int i = 0; i < last_count; i++) {
+            char ts[20];
+            struct tm tmi;
+            localtime_r(&last_msgs[i].timestamp, &tmi);
+            strftime(ts, sizeof(ts), "%m-%d %H:%M", &tmi);
+            buffer_appendf(output, sizeof(output), &pos,
+                           "[%s] %s: %s\n", ts, last_msgs[i].username, last_msgs[i].content);
+        }
+        free(last_msgs);
+
+    } else if (strncmp(cmd, "search ", 7) == 0) {
+        char *query = cmd + 7;
+        while (*query == ' ') query++;
+        if (*query == '\0') {
+            buffer_appendf(output, sizeof(output), &pos,
+                           "Usage: search <keyword>\n");
+        } else {
+            message_t *found = NULL;
+            int found_count = message_search(query, &found, 15);
+            buffer_appendf(output, sizeof(output), &pos,
+                           "--- Search: \"%s\" (%d match(es)) ---\n", query, found_count);
+            for (int i = 0; i < found_count; i++) {
+                char ts[20];
+                struct tm tmi;
+                localtime_r(&found[i].timestamp, &tmi);
+                strftime(ts, sizeof(ts), "%m-%d %H:%M", &tmi);
+                buffer_appendf(output, sizeof(output), &pos,
+                               "[%s] %s: %s\n", ts, found[i].username, found[i].content);
+            }
+            free(found);
+        }
+
+    } else if (strcmp(cmd, "mute-joins") == 0 || strcmp(cmd, "mute") == 0) {
+        client->mute_joins = !client->mute_joins;
+        buffer_appendf(output, sizeof(output), &pos,
+                       "Join/leave notifications: %s\n",
+                       client->mute_joins ? "muted" : "unmuted");
+
     } else if (strcmp(cmd, "q") == 0 || strcmp(cmd, "quit") == 0 ||
                strcmp(cmd, "exit") == 0) {
         client->connected = false;
@@ -1310,6 +1370,7 @@ static void execute_command(client_t *client) {
                        "Type 'help' for available commands\n", cmd);
     }
 
+cmd_done:
     buffer_appendf(output, sizeof(output), &pos,
                    "\nPress any key to continue...");
 
@@ -1607,10 +1668,33 @@ void* client_handle_session(void *arg) {
     room_broadcast(g_room, &join_msg);
     message_save(&join_msg);
 
+    /* Show MOTD if motd.txt exists in state directory */
+    {
+        char motd_path[PATH_MAX];
+        if (tnt_state_path(motd_path, sizeof(motd_path), "motd.txt") == 0) {
+            FILE *motd_fp = fopen(motd_path, "r");
+            if (motd_fp) {
+                char motd_buf[sizeof(client->command_output) - 64];
+                size_t motd_len = fread(motd_buf, 1, sizeof(motd_buf) - 1, motd_fp);
+                fclose(motd_fp);
+                if (motd_len > 0) {
+                    motd_buf[motd_len] = '\0';
+                    snprintf(client->command_output, sizeof(client->command_output),
+                             "=== 公告 / MOTD ===\n%s", motd_buf);
+                    tui_render_command_output(client);
+                    seen_update_seq = room_get_update_seq(g_room);
+                    goto main_loop;
+                }
+            }
+        }
+    }
+
     /* Render initial screen */
     tui_render_screen(client);
     seen_update_seq = room_get_update_seq(g_room);
 
+main_loop:
+
     /* Main input loop */
     while (client->connected && ssh_channel_is_open(client->channel)) {
         int ready = ssh_channel_poll_timeout(client->channel, 1000, 0);

src/tui.c

@@ -5,6 +5,12 @@
 #include <stdarg.h>
 #include <unistd.h>
 
+static bool is_join_leave_msg(const message_t *msg) {
+    if (strcmp(msg->username, "系统") != 0) return false;
+    return strstr(msg->content, "加入了聊天室") != NULL ||
+           strstr(msg->content, "离开了聊天室") != NULL;
+}
+
 static const char *username_color(const char *name) {
     static const char *colors[] = {
         "\033[31m", "\033[32m", "\033[33m",
@@ -222,6 +228,17 @@ void tui_render_screen(client_t *client) {
 
     /* Now render using snapshot (no lock held) */
 
+    /* If mute_joins is set, remove join/leave messages from snapshot in place */
+    if (client->mute_joins && msg_snapshot) {
+        int filtered = 0;
+        for (int i = 0; i < snapshot_count; i++) {
+            if (!is_join_leave_msg(&msg_snapshot[i])) {
+                msg_snapshot[filtered++] = msg_snapshot[i];
+            }
+        }
+        snapshot_count = filtered;
+    }
+
     /* Move to top (Home) - Do NOT clear screen to prevent flicker */
     buffer_appendf(buffer, buf_size, &pos, ANSI_HOME);
 
@@ -232,8 +249,9 @@ void tui_render_screen(client_t *client) {
 
     char title[256];
     snprintf(title, sizeof(title),
-             " %s | 在线: %d | 模式: %s | ? 帮助 ",
-             client->username, online, mode_str);
+             " %s | 在线: %d | 模式: %s%s | ? 帮助 ",
+             client->username, online, mode_str,
+             client->mute_joins ? " [静音]" : "");
 
     int title_width = utf8_string_width(title);
     int padding = render_width - title_width;
@@ -419,6 +437,9 @@ const char* tui_get_help_text(help_lang_t lang) {
                "  :nick <name>         - Change nickname\n"
                "  :msg <user> <text>   - Whisper to user\n"
                "  :w <user> <text>     - Short alias for :msg\n"
+               "  :last [N]            - Show last N messages (max 50)\n"
+               "  :search <keyword>    - Search message history\n"
+               "  :mute-joins          - Toggle join/leave notices\n"
                "  :help                - Show available commands\n"
                "  :clear               - Clear command output\n"
                "  :q, :quit, :exit     - Disconnect\n"
@@ -463,6 +484,9 @@ const char* tui_get_help_text(help_lang_t lang) {
                "  :nick <名字>         - 更改昵称\n"
                "  :msg <用户> <文本>   - 私聊\n"
                "  :w <用户> <文本>     - :msg 的简写\n"
+               "  :last [N]            - 显示最后 N 条消息(最多50)\n"
+               "  :search <关键词>     - 搜索消息历史\n"
+               "  :mute-joins          - 切换加入/离开提示\n"
                "  :help                - 显示可用命令\n"
                "  :clear               - 清空命令输出\n"
                "  :q, :quit, :exit     - 断开连接\n"

tnt.1

@@ -107,6 +107,9 @@ l l.
 :name \fIname\fR	Alias for :nick
 :msg \fIuser text\fR	Send private whisper
 :w \fIuser text\fR	Short alias for :msg
+:last [\fIN\fR]	Show last N messages from history (1\-50, default 10)
+:search \fIkeyword\fR	Case\-insensitive search across full message history
+:mute\-joins	Toggle join/leave system notifications on/off
 :help	Show available commands
 :clear	Clear command output
 :q, :quit, :exit	Disconnect
@@ -167,6 +170,12 @@ Stored in the state directory.
 .I host_key
 RSA 4096\-bit host key, auto\-generated on first run.
 Stored in the state directory with mode 0600.
+.TP
+.I motd.txt
+Optional Message of the Day.
+When present in the state directory, its contents are shown to each user
+immediately on connect before the chat screen appears.
+Delete the file to disable the MOTD.
 .SH SYSTEMD
 A unit file
 .I tnt.service