diff --git a/.gitignore b/.gitignore
index e4ea543..75e99b0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,4 +24,5 @@ tests/unit/test_help_text
 tests/unit/test_manual_text
 tests/unit/test_support_text
 tests/unit/test_cli_text
+tests/unit/test_tntctl_text
 tests/unit/test_ratelimit
diff --git a/Makefile b/Makefile
index fdbec19..bb1828f 100644
--- a/Makefile
+++ b/Makefile
@@ -20,12 +20,12 @@ SRC_DIR = src
 INC_DIR = include
 OBJ_DIR = obj
 
-SOURCES = $(filter-out $(SRC_DIR)/tntctl.c,$(wildcard $(SRC_DIR)/*.c))
+SOURCES = $(filter-out $(SRC_DIR)/tntctl.c $(SRC_DIR)/tntctl_text.c,$(wildcard $(SRC_DIR)/*.c))
 OBJECTS = $(SOURCES:$(SRC_DIR)/%.c=$(OBJ_DIR)/%.o)
 DEPS = $(OBJECTS:.o=.d) $(CTL_OBJECTS:.o=.d)
 TARGET = tnt
 CTL_TARGET = tntctl
-CTL_OBJECTS = $(OBJ_DIR)/tntctl.o $(OBJ_DIR)/exec_catalog.o $(OBJ_DIR)/common.o $(OBJ_DIR)/i18n.o
+CTL_OBJECTS = $(OBJ_DIR)/tntctl.o $(OBJ_DIR)/tntctl_text.o $(OBJ_DIR)/exec_catalog.o $(OBJ_DIR)/common.o $(OBJ_DIR)/i18n.o
 TARGETS = $(TARGET) $(CTL_TARGET)
 
 PREFIX ?= /usr/local
diff --git a/README.md b/README.md
index 7adf3e0..d2018c9 100644
--- a/README.md
+++ b/README.md
@@ -324,6 +324,7 @@ TNT/
 │   ├── exec_catalog.c # SSH exec command matching, usage, and argument shape
 │   ├── exec.c        # SSH exec command dispatch
 │   ├── tntctl.c      # local wrapper around the SSH exec interface
+│   ├── tntctl_text.c # tntctl help and option text
 │   ├── ssh_server.c  # SSH server implementation
 │   ├── bootstrap.c   # SSH authentication and session bootstrap
 │   ├── chat_room.c   # chat room logic
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index fef20c3..9a0fe78 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -3,6 +3,8 @@
 ## Unreleased
 
 ### Added
+- Added a dedicated `tntctl_text` module with unit coverage for local
+  `tntctl` help and validation diagnostics.
 - Documented the stable SSH exec interface contract, including exit statuses
   and JSON field shapes for package tests, scripts, and future `tntctl` work.
 - Documented `messages.log` v1 as the stable TNT 1.x persisted history format,
diff --git a/docs/CONTRIBUTING.md b/docs/CONTRIBUTING.md
index 872d6d4..0024080 100644
--- a/docs/CONTRIBUTING.md
+++ b/docs/CONTRIBUTING.md
@@ -40,6 +40,7 @@ make check
 ```
 main.c           → entry point, signal handling
 cli_text.c       → startup CLI text
+tntctl_text.c    → tntctl local help and diagnostics
 command_catalog.c → COMMAND-mode command metadata, usage, and argument shape
 commands.c       → COMMAND-mode command dispatch
 exec_catalog.c   → SSH exec command matching, usage, and argument shape
diff --git a/docs/QUICKREF.md b/docs/QUICKREF.md
index ca3f015..65809b0 100644
--- a/docs/QUICKREF.md
+++ b/docs/QUICKREF.md
@@ -66,6 +66,7 @@ MAINTENANCE
 STRUCTURE
   src/main.c          entry, signals
   src/cli_text.c      startup CLI text
+  src/tntctl_text.c   tntctl local help and diagnostics
   src/command_catalog.c command metadata, usage, argument shape
   src/ssh_server.c    SSH listener and server setup
   src/bootstrap.c     SSH auth/session bootstrap
diff --git a/include/tntctl_text.h b/include/tntctl_text.h
new file mode 100644
index 0000000..ed8c385
--- /dev/null
+++ b/include/tntctl_text.h
@@ -0,0 +1,28 @@
+#ifndef TNTCTL_TEXT_H
+#define TNTCTL_TEXT_H
+
+#include "common.h"
+
+typedef enum {
+    TNTCTL_TEXT_USAGE,
+    TNTCTL_TEXT_INVALID_PORT,
+    TNTCTL_TEXT_INVALID_LOGIN,
+    TNTCTL_TEXT_INVALID_HOST_KEY_MODE,
+    TNTCTL_TEXT_INVALID_KNOWN_HOSTS,
+    TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT,
+    TNTCTL_TEXT_MISSING_HOST,
+    TNTCTL_TEXT_INVALID_HOST,
+    TNTCTL_TEXT_LOGIN_HOST_CONFLICT,
+    TNTCTL_TEXT_UNKNOWN_COMMAND,
+    TNTCTL_TEXT_INVALID_REMOTE_COMMAND,
+    TNTCTL_TEXT_DESTINATION_TOO_LONG,
+    TNTCTL_TEXT_INVALID_DESTINATION,
+    TNTCTL_TEXT_OUT_OF_MEMORY,
+    TNTCTL_TEXT_HOST_KEY_OPTION_TOO_LONG,
+    TNTCTL_TEXT_KNOWN_HOSTS_OPTION_TOO_LONG,
+    TNTCTL_TEXT_COUNT
+} tntctl_text_id_t;
+
+const char *tntctl_text(ui_lang_t lang, tntctl_text_id_t id);
+
+#endif /* TNTCTL_TEXT_H */
diff --git a/src/tntctl.c b/src/tntctl.c
index 20f4590..47dbb0c 100644
--- a/src/tntctl.c
+++ b/src/tntctl.c
@@ -1,6 +1,7 @@
 #include "common.h"
 #include "exec_catalog.h"
 #include "i18n.h"
+#include "tntctl_text.h"
 
 #include <ctype.h>
 #include <errno.h>
@@ -8,113 +9,6 @@
 #include <sys/wait.h>
 #include <unistd.h>
 
-typedef enum {
-    TNTCTL_TEXT_USAGE,
-    TNTCTL_TEXT_INVALID_PORT,
-    TNTCTL_TEXT_INVALID_LOGIN,
-    TNTCTL_TEXT_INVALID_HOST_KEY_MODE,
-    TNTCTL_TEXT_INVALID_KNOWN_HOSTS,
-    TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT,
-    TNTCTL_TEXT_MISSING_HOST,
-    TNTCTL_TEXT_INVALID_HOST,
-    TNTCTL_TEXT_LOGIN_HOST_CONFLICT,
-    TNTCTL_TEXT_UNKNOWN_COMMAND,
-    TNTCTL_TEXT_INVALID_REMOTE_COMMAND,
-    TNTCTL_TEXT_DESTINATION_TOO_LONG,
-    TNTCTL_TEXT_INVALID_DESTINATION,
-    TNTCTL_TEXT_OUT_OF_MEMORY,
-    TNTCTL_TEXT_HOST_KEY_OPTION_TOO_LONG,
-    TNTCTL_TEXT_KNOWN_HOSTS_OPTION_TOO_LONG,
-    TNTCTL_TEXT_COUNT
-} tntctl_text_id_t;
-
-static const i18n_string_t tntctl_text_catalog[TNTCTL_TEXT_COUNT] = {
-    [TNTCTL_TEXT_USAGE] = I18N_STRING(
-        "Usage: tntctl [options] host command [args...]\n"
-        "\n"
-        "Options:\n"
-        "  -p, --port PORT        SSH port (default: 2222)\n"
-        "  -l, --login USER       SSH login name for exec identity\n"
-        "  --host-key-checking MODE\n"
-        "                         OpenSSH host-key mode: yes, accept-new, no\n"
-        "  --known-hosts FILE     OpenSSH known_hosts file\n"
-        "  -V, --version          Print version and exit\n"
-        "  -h, --help             Print this help and exit\n"
-        "\n"
-        "Commands mirror the TNT SSH exec interface: health, stats, users,\n"
-        "tail, dump, post, help, and exit.\n",
-        "用法: tntctl [options] host command [args...]\n"
-        "\n"
-        "选项:\n"
-        "  -p, --port PORT        SSH 端口 (默认: 2222)\n"
-        "  -l, --login USER       SSH 登录名，用作 exec 身份\n"
-        "  --host-key-checking MODE\n"
-        "                         OpenSSH 主机密钥模式: yes, accept-new, no\n"
-        "  --known-hosts FILE     OpenSSH known_hosts 文件\n"
-        "  -V, --version          输出版本并退出\n"
-        "  -h, --help             输出此帮助并退出\n"
-        "\n"
-        "命令对应 TNT SSH exec 接口: health, stats, users,\n"
-        "tail, dump, post, help 和 exit.\n"
-    ),
-    [TNTCTL_TEXT_INVALID_PORT] = I18N_STRING(
-        "invalid port", "端口无效"
-    ),
-    [TNTCTL_TEXT_INVALID_LOGIN] = I18N_STRING(
-        "invalid login", "登录名无效"
-    ),
-    [TNTCTL_TEXT_INVALID_HOST_KEY_MODE] = I18N_STRING(
-        "invalid host-key checking mode", "主机密钥检查模式无效"
-    ),
-    [TNTCTL_TEXT_INVALID_KNOWN_HOSTS] = I18N_STRING(
-        "invalid known_hosts path", "known_hosts 路径无效"
-    ),
-    [TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT] = I18N_STRING(
-        "unknown option: %s", "未知选项: %s"
-    ),
-    [TNTCTL_TEXT_MISSING_HOST] = I18N_STRING(
-        "missing host", "缺少 host"
-    ),
-    [TNTCTL_TEXT_INVALID_HOST] = I18N_STRING(
-        "invalid host", "host 无效"
-    ),
-    [TNTCTL_TEXT_LOGIN_HOST_CONFLICT] = I18N_STRING(
-        "use either --login or user@host, not both",
-        "只能使用 --login 或 user@host 之一"
-    ),
-    [TNTCTL_TEXT_UNKNOWN_COMMAND] = I18N_STRING(
-        "unknown or missing command", "未知命令或缺少命令"
-    ),
-    [TNTCTL_TEXT_INVALID_REMOTE_COMMAND] = I18N_STRING(
-        "invalid or too-long command", "命令无效或过长"
-    ),
-    [TNTCTL_TEXT_DESTINATION_TOO_LONG] = I18N_STRING(
-        "destination too long", "目标地址过长"
-    ),
-    [TNTCTL_TEXT_INVALID_DESTINATION] = I18N_STRING(
-        "invalid destination", "目标地址无效"
-    ),
-    [TNTCTL_TEXT_OUT_OF_MEMORY] = I18N_STRING(
-        "out of memory", "内存不足"
-    ),
-    [TNTCTL_TEXT_HOST_KEY_OPTION_TOO_LONG] = I18N_STRING(
-        "host-key option too long", "主机密钥选项过长"
-    ),
-    [TNTCTL_TEXT_KNOWN_HOSTS_OPTION_TOO_LONG] = I18N_STRING(
-        "known_hosts option too long", "known_hosts 选项过长"
-    )
-};
-typedef char tntctl_text_catalog_must_cover_enum[
-    sizeof(tntctl_text_catalog) / sizeof(tntctl_text_catalog[0]) ==
-    TNTCTL_TEXT_COUNT ? 1 : -1];
-
-static const char *tntctl_text(ui_lang_t lang, tntctl_text_id_t id) {
-    if (id < 0 || id >= TNTCTL_TEXT_COUNT) {
-        return "";
-    }
-    return i18n_string(tntctl_text_catalog[id], lang);
-}
-
 static void print_usage(FILE *stream, ui_lang_t lang) {
     fputs(tntctl_text(lang, TNTCTL_TEXT_USAGE), stream);
 }
diff --git a/src/tntctl_text.c b/src/tntctl_text.c
new file mode 100644
index 0000000..a0090b7
--- /dev/null
+++ b/src/tntctl_text.c
@@ -0,0 +1,89 @@
+#include "tntctl_text.h"
+
+#include "i18n.h"
+
+static const i18n_string_t text_catalog[TNTCTL_TEXT_COUNT] = {
+    [TNTCTL_TEXT_USAGE] = I18N_STRING(
+        "Usage: tntctl [options] host command [args...]\n"
+        "\n"
+        "Options:\n"
+        "  -p, --port PORT        SSH port (default: 2222)\n"
+        "  -l, --login USER       SSH login name for exec identity\n"
+        "  --host-key-checking MODE\n"
+        "                         OpenSSH host-key mode: yes, accept-new, no\n"
+        "  --known-hosts FILE     OpenSSH known_hosts file\n"
+        "  -V, --version          Print version and exit\n"
+        "  -h, --help             Print this help and exit\n"
+        "\n"
+        "Commands mirror the TNT SSH exec interface: health, stats, users,\n"
+        "tail, dump, post, help, and exit.\n",
+        "用法: tntctl [options] host command [args...]\n"
+        "\n"
+        "选项:\n"
+        "  -p, --port PORT        SSH 端口 (默认: 2222)\n"
+        "  -l, --login USER       SSH 登录名，用作 exec 身份\n"
+        "  --host-key-checking MODE\n"
+        "                         OpenSSH 主机密钥模式: yes, accept-new, no\n"
+        "  --known-hosts FILE     OpenSSH known_hosts 文件\n"
+        "  -V, --version          输出版本并退出\n"
+        "  -h, --help             输出此帮助并退出\n"
+        "\n"
+        "命令对应 TNT SSH exec 接口: health, stats, users,\n"
+        "tail, dump, post, help 和 exit.\n"
+    ),
+    [TNTCTL_TEXT_INVALID_PORT] = I18N_STRING(
+        "invalid port", "端口无效"
+    ),
+    [TNTCTL_TEXT_INVALID_LOGIN] = I18N_STRING(
+        "invalid login", "登录名无效"
+    ),
+    [TNTCTL_TEXT_INVALID_HOST_KEY_MODE] = I18N_STRING(
+        "invalid host-key checking mode", "主机密钥检查模式无效"
+    ),
+    [TNTCTL_TEXT_INVALID_KNOWN_HOSTS] = I18N_STRING(
+        "invalid known_hosts path", "known_hosts 路径无效"
+    ),
+    [TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT] = I18N_STRING(
+        "unknown option: %s", "未知选项: %s"
+    ),
+    [TNTCTL_TEXT_MISSING_HOST] = I18N_STRING(
+        "missing host", "缺少 host"
+    ),
+    [TNTCTL_TEXT_INVALID_HOST] = I18N_STRING(
+        "invalid host", "host 无效"
+    ),
+    [TNTCTL_TEXT_LOGIN_HOST_CONFLICT] = I18N_STRING(
+        "use either --login or user@host, not both",
+        "只能使用 --login 或 user@host 之一"
+    ),
+    [TNTCTL_TEXT_UNKNOWN_COMMAND] = I18N_STRING(
+        "unknown or missing command", "未知命令或缺少命令"
+    ),
+    [TNTCTL_TEXT_INVALID_REMOTE_COMMAND] = I18N_STRING(
+        "invalid or too-long command", "命令无效或过长"
+    ),
+    [TNTCTL_TEXT_DESTINATION_TOO_LONG] = I18N_STRING(
+        "destination too long", "目标地址过长"
+    ),
+    [TNTCTL_TEXT_INVALID_DESTINATION] = I18N_STRING(
+        "invalid destination", "目标地址无效"
+    ),
+    [TNTCTL_TEXT_OUT_OF_MEMORY] = I18N_STRING(
+        "out of memory", "内存不足"
+    ),
+    [TNTCTL_TEXT_HOST_KEY_OPTION_TOO_LONG] = I18N_STRING(
+        "host-key option too long", "主机密钥选项过长"
+    ),
+    [TNTCTL_TEXT_KNOWN_HOSTS_OPTION_TOO_LONG] = I18N_STRING(
+        "known_hosts option too long", "known_hosts 选项过长"
+    )
+};
+typedef char text_catalog_must_cover_enum[
+    sizeof(text_catalog) / sizeof(text_catalog[0]) == TNTCTL_TEXT_COUNT ? 1 : -1];
+
+const char *tntctl_text(ui_lang_t lang, tntctl_text_id_t id) {
+    if (id < 0 || id >= TNTCTL_TEXT_COUNT) {
+        return "";
+    }
+    return i18n_string(text_catalog[id], lang);
+}
diff --git a/tests/unit/Makefile b/tests/unit/Makefile
index c6667c6..25bc8b5 100644
--- a/tests/unit/Makefile
+++ b/tests/unit/Makefile
@@ -16,6 +16,7 @@ MESSAGE_LOG_SRC = ../../src/message_log.c
 COMMON_SRC = ../../src/common.c
 COMMAND_CATALOG_SRC = ../../src/command_catalog.c
 CLI_TEXT_SRC = ../../src/cli_text.c
+TNTCTL_TEXT_SRC = ../../src/tntctl_text.c
 CHAT_ROOM_SRC = ../../src/chat_room.c
 HISTORY_VIEW_SRC = ../../src/history_view.c
 I18N_SRC = ../../src/i18n.c
@@ -26,7 +27,7 @@ HELP_TEXT_SRC = ../../src/help_text.c
 MANUAL_TEXT_SRC = ../../src/manual_text.c
 RATELIMIT_SRC = ../../src/ratelimit.c
 
-TESTS = test_utf8 test_message test_chat_room test_history_view test_i18n test_system_message test_command_catalog test_exec_catalog test_help_text test_manual_text test_cli_text test_ratelimit
+TESTS = test_utf8 test_message test_chat_room test_history_view test_i18n test_system_message test_command_catalog test_exec_catalog test_help_text test_manual_text test_cli_text test_tntctl_text test_ratelimit
 
 .PHONY: all clean run
 
@@ -65,6 +66,9 @@ test_manual_text: test_manual_text.c $(MANUAL_TEXT_SRC) $(COMMAND_CATALOG_SRC) $
 test_cli_text: test_cli_text.c $(CLI_TEXT_SRC) $(COMMON_SRC)
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 
+test_tntctl_text: test_tntctl_text.c $(TNTCTL_TEXT_SRC)
+	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
+
 test_ratelimit: test_ratelimit.c $(RATELIMIT_SRC) $(COMMON_SRC)
 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS)
 
@@ -102,6 +106,9 @@ run: all
 	@echo "=== Running CLI Text Tests ==="
 	./test_cli_text
 	@echo ""
+	@echo "=== Running tntctl Text Tests ==="
+	./test_tntctl_text
+	@echo ""
 	@echo "=== Running Rate Limit Tests ==="
 	./test_ratelimit
 
diff --git a/tests/unit/test_tntctl_text.c b/tests/unit/test_tntctl_text.c
new file mode 100644
index 0000000..b303ad5
--- /dev/null
+++ b/tests/unit/test_tntctl_text.c
@@ -0,0 +1,53 @@
+/* Unit tests for tntctl local help and diagnostic text */
+
+#include "../../include/tntctl_text.h"
+#include <assert.h>
+#include <stdio.h>
+#include <string.h>
+
+#define TEST(name) static void test_##name()
+#define RUN_TEST(name) do { \
+    printf("Running %s... ", #name); \
+    test_##name(); \
+    printf("✓\n"); \
+    tests_passed++; \
+} while(0)
+
+static int tests_passed = 0;
+
+TEST(usage_matches_language) {
+    const char *en = tntctl_text(UI_LANG_EN, TNTCTL_TEXT_USAGE);
+    const char *zh = tntctl_text(UI_LANG_ZH, TNTCTL_TEXT_USAGE);
+
+    assert(strstr(en, "Usage: tntctl [options] host command [args...]") != NULL);
+    assert(strstr(en, "--host-key-checking MODE") != NULL);
+    assert(strstr(en, "health, stats, users") != NULL);
+    assert(strstr(zh, "用法: tntctl [options] host command [args...]") != NULL);
+    assert(strstr(zh, "OpenSSH 主机密钥模式") != NULL);
+    assert(strstr(zh, "health, stats, users") != NULL);
+}
+
+TEST(errors_match_language) {
+    assert(strcmp(tntctl_text(UI_LANG_EN, TNTCTL_TEXT_INVALID_PORT),
+                  "invalid port") == 0);
+    assert(strcmp(tntctl_text(UI_LANG_ZH, TNTCTL_TEXT_INVALID_PORT),
+                  "端口无效") == 0);
+    assert(strcmp(tntctl_text(UI_LANG_EN, TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT),
+                  "unknown option: %s") == 0);
+    assert(strcmp(tntctl_text(UI_LANG_ZH, TNTCTL_TEXT_UNKNOWN_OPTION_FORMAT),
+                  "未知选项: %s") == 0);
+    assert(strcmp(tntctl_text((ui_lang_t)99, TNTCTL_TEXT_INVALID_PORT),
+                  "invalid port") == 0);
+    assert(strcmp(tntctl_text(UI_LANG_EN,
+                              (tntctl_text_id_t)TNTCTL_TEXT_COUNT), "") == 0);
+}
+
+int main(void) {
+    printf("Running tntctl text unit tests...\n\n");
+
+    RUN_TEST(usage_matches_language);
+    RUN_TEST(errors_match_language);
+
+    printf("\n✓ All %d tests passed!\n", tests_passed);
+    return 0;
+}