diff --git a/AI.md b/AI.md
index caeb1f8..7d8ea7a 100644
--- a/AI.md
+++ b/AI.md
@@ -47,7 +47,7 @@ unfinished work out of `TODO.md` merely because its architecture is documented.
 
 Latest patch marker expected in an up-to-date bundle:
 
-- `0459 test: isolate FLAIM smoke test work directories`
+- `0460 test: add core NSS helper unit coverage`
 
 When a later chat receives a new `mars-nwe-master` bundle, compare `git log -1`
 with this marker.  If the uploaded bundle already contains this commit subject,
@@ -67,17 +67,16 @@ The active line is expected to include:
 
 Last generated patch:
 
-- `0459 test: isolate FLAIM smoke test work directories`
+- `0460 test: add core NSS helper unit coverage`
 
 Purpose of that patch:
 
-- Fix FLAIM smoke tests that can fail after stale or root-owned build-tree
-  work directories are left behind.  The mars-nwe FLAIM API smoke now creates a
-  unique temporary work directory derived from the configured base path instead
-  of reusing `tests/flaim/flaim-api` directly.  Apply the matching mars-flaim
-  submodule patch for the imported `nwflaim.database.create-and-check` CTest
-  script, which similarly avoids the fixed `third_party/flaim/ctest/nwflaim-db`
-  directory.
+- Add focused CTest coverage for the imported low-level NSS helper line in
+  `libnwcore`: bit operations, bitmap allocation/search, CRC/hash behavior,
+  xCtype classification/case conversion, xString compatibility helpers, and
+  UTF-8/Unicode round-trips.  Keep the tests in subsystem directories under
+  `tests/core/` so later codepage, byte-converter, GUID/ID, UTC, and Unicode
+  table tests can be added without flattening the test tree.
 
 Rejected or superseded patches that must not be reused as-is:
 
diff --git a/tests/README.md b/tests/README.md
index da9475d..4c9c82b 100644
--- a/tests/README.md
+++ b/tests/README.md
@@ -9,8 +9,11 @@ exercise outside the normal install flow.
 `tests/core` contains normal CTest unit tests for `libnwcore` facilities.
 Keep them grouped by core subsystem: `tests/core/ini` covers the shared
 `nw_ini_*` reader/writer facade, `tests/core/log` covers the `nwlog_*`
-level-mask facade, and future Unicode/codepage/UTF-8/byte/bitmap tests should
-get their own sibling subdirectories instead of being added as a flat list.
+level-mask facade, and imported NSS low-level helpers are covered by sibling
+subdirectories such as `tests/core/bit`, `tests/core/bitmap`,
+`tests/core/crc`, `tests/core/xctype`, `tests/core/xstring`, and
+`tests/core/utf8`.  Future Unicode/codepage/byte coverage should keep using
+new focused sibling subdirectories instead of being added as a flat list.
 
 `tests/tui` contains non-interactive `libnwtui` smoke tests.  These tests must
 not require a real terminal or compare full-screen terminal output; test widget
diff --git a/tests/core/CMakeLists.txt b/tests/core/CMakeLists.txt
index 976af5f..ff87d3b 100644
--- a/tests/core/CMakeLists.txt
+++ b/tests/core/CMakeLists.txt
@@ -4,3 +4,9 @@
 
 add_subdirectory(ini)
 add_subdirectory(log)
+add_subdirectory(bit)
+add_subdirectory(bitmap)
+add_subdirectory(crc)
+add_subdirectory(xctype)
+add_subdirectory(xstring)
+add_subdirectory(utf8)
diff --git a/tests/core/bit/CMakeLists.txt b/tests/core/bit/CMakeLists.txt
new file mode 100644
index 0000000..1fd04cc
--- /dev/null
+++ b/tests/core/bit/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_bit
+    test_nwcore_bit.c)
+
+target_compile_features(test_nwcore_bit PRIVATE c_std_99)
+target_include_directories(test_nwcore_bit PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_bit PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_bit COMMAND test_nwcore_bit)
diff --git a/tests/core/bit/test_nwcore_bit.c b/tests/core/bit/test_nwcore_bit.c
new file mode 100644
index 0000000..be01338
--- /dev/null
+++ b/tests/core/bit/test_nwcore_bit.c
@@ -0,0 +1,36 @@
+#include "bit.h"
+
+#include <stdint.h>
+#include <stdio.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  CHECK(LB_CountBits(0) == 0);
+  CHECK(LB_CountBits(1) == 1);
+  CHECK(LB_CountBits((NINT)0x0000f0f0U) == 8);
+  CHECK(LB_CountBits((NINT)0xffffffffU) == 32);
+
+  CHECK(LB_findHighBit(0) == (NINT)-1);
+  CHECK(LB_findHighBit(1) == 0);
+  CHECK(LB_findHighBit(0x10) == 4);
+  CHECK(LB_findHighBit((NINT)0x80000000U) == 31);
+
+  CHECK(LB_findLowBit(0) == (NINT)-1);
+  CHECK(LB_findLowBit(1) == 0);
+  CHECK(LB_findLowBit(0x10) == 4);
+  CHECK(LB_findLowBit((NINT)0x80000000U) == 31);
+
+  CHECK((uint32_t)LB_RotateLeft((NINT)0x12345678U, 8) == 0x34567812U);
+  CHECK((uint32_t)LB_RotateRight((NINT)0x12345678U, 8) == 0x78123456U);
+  CHECK((uint32_t)LB_RotateLeft((NINT)0x12345678U, 0) == 0x12345678U);
+  CHECK((uint32_t)LB_RotateRight((NINT)0x12345678U, 32) == 0x12345678U);
+  return 0;
+}
diff --git a/tests/core/bitmap/CMakeLists.txt b/tests/core/bitmap/CMakeLists.txt
new file mode 100644
index 0000000..59b8728
--- /dev/null
+++ b/tests/core/bitmap/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_bitmap
+    test_nwcore_bitmap.c)
+
+target_compile_features(test_nwcore_bitmap PRIVATE c_std_99)
+target_include_directories(test_nwcore_bitmap PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_bitmap PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_bitmap COMMAND test_nwcore_bitmap)
diff --git a/tests/core/bitmap/test_nwcore_bitmap.c b/tests/core/bitmap/test_nwcore_bitmap.c
new file mode 100644
index 0000000..45eb1bc
--- /dev/null
+++ b/tests/core/bitmap/test_nwcore_bitmap.c
@@ -0,0 +1,48 @@
+#include "bitmap.h"
+
+#include <stdio.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  BitMap_s map;
+  SNINT start;
+
+  CHECK(newBitMap(&map, 20) == &map);
+  CHECK(getMaxBits(&map) == 20);
+  CHECK(countBits(&map) == 20);
+  CHECK(testABit(&map, 0));
+  CHECK(testABit(&map, 19));
+
+  start = findBits(&map, 4);
+  CHECK(start == 0);
+  CHECK(countBits(&map) == 16);
+  CHECK(!testABit(&map, 0));
+  CHECK(!testABit(&map, 3));
+  CHECK(testABit(&map, 4));
+
+  setAbit(&map, 1);
+  CHECK(testABit(&map, 1));
+  clearAbit(&map, 1);
+  CHECK(!testABit(&map, 1));
+
+  clearBits(&map, 8, 4);
+  CHECK(!testABit(&map, 8));
+  CHECK(!testABit(&map, 11));
+  setBits(&map, 8, 2);
+  CHECK(testABit(&map, 8));
+  CHECK(testABit(&map, 9));
+  CHECK(!testABit(&map, 10));
+
+  start = findBits(&map, 4);
+  CHECK(start == 4);
+  freeBitMap(&map);
+  return 0;
+}
diff --git a/tests/core/crc/CMakeLists.txt b/tests/core/crc/CMakeLists.txt
new file mode 100644
index 0000000..6025c64
--- /dev/null
+++ b/tests/core/crc/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_crc
+    test_nwcore_crc.c)
+
+target_compile_features(test_nwcore_crc PRIVATE c_std_99)
+target_include_directories(test_nwcore_crc PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_crc PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_crc COMMAND test_nwcore_crc)
diff --git a/tests/core/crc/test_nwcore_crc.c b/tests/core/crc/test_nwcore_crc.c
new file mode 100644
index 0000000..1cecf47
--- /dev/null
+++ b/tests/core/crc/test_nwcore_crc.c
@@ -0,0 +1,31 @@
+#include "crc.h"
+
+#include <stdint.h>
+#include <stdio.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  BYTE input[] = "123456789";
+  char mixed[] = "Mars-NWE";
+  char lower[] = "mars-nwe";
+  crc_t running;
+
+  CHECK((uint32_t)crc(input, 9) == 0xcbf43926U);
+
+  running = updateCRC((crc_t)~0L, input, 4);
+  running = updateCRC(running, input + 4, 5);
+  CHECK((uint32_t)~running == 0xcbf43926U);
+
+  CHECK(hashLowerString(mixed) == hashLowerString(lower));
+  CHECK(hashString(mixed) != hashLowerString(mixed));
+  CHECK(lowerStringCRC(mixed) == lowerStringCRC(lower));
+  return 0;
+}
diff --git a/tests/core/utf8/CMakeLists.txt b/tests/core/utf8/CMakeLists.txt
new file mode 100644
index 0000000..260bf27
--- /dev/null
+++ b/tests/core/utf8/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_utf8
+    test_nwcore_utf8.c)
+
+target_compile_features(test_nwcore_utf8 PRIVATE c_std_99)
+target_include_directories(test_nwcore_utf8 PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_utf8 PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_utf8 COMMAND test_nwcore_utf8)
diff --git a/tests/core/utf8/test_nwcore_utf8.c b/tests/core/utf8/test_nwcore_utf8.c
new file mode 100644
index 0000000..8fe8a5d
--- /dev/null
+++ b/tests/core/utf8/test_nwcore_utf8.c
@@ -0,0 +1,43 @@
+#include "xUnicode.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  utf8_t ascii[] = "Mars";
+  utf8_t utf8_word[] = { 'M', 0xc3, 0xa4, 'r', 'z', 0 };
+  unicode_t unicode[16];
+  utf8_t out[16];
+  NINT n;
+
+  n = utf2uni(ascii, unicode, sizeof(unicode));
+  CHECK(n == 4);
+  CHECK(unicode[0] == 'M');
+  CHECK(unicode[3] == 's');
+  CHECK(unicode[4] == 0);
+
+  n = uni2utf(unicode, out, sizeof(out));
+  CHECK(n == 4);
+  CHECK(strcmp((char *)out, "Mars") == 0);
+
+  n = utf2uni(utf8_word, unicode, sizeof(unicode));
+  CHECK(n == 4);
+  CHECK(unicode[0] == 'M');
+  CHECK(unicode[1] == 0x00e4);
+  CHECK(unicode[2] == 'r');
+  CHECK(unicode[3] == 'z');
+
+  n = uni2utf(unicode, out, sizeof(out));
+  CHECK(n == 5);
+  CHECK(memcmp(out, utf8_word, 6) == 0);
+  return 0;
+}
diff --git a/tests/core/xctype/CMakeLists.txt b/tests/core/xctype/CMakeLists.txt
new file mode 100644
index 0000000..2523e54
--- /dev/null
+++ b/tests/core/xctype/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_xctype
+    test_nwcore_xctype.c)
+
+target_compile_features(test_nwcore_xctype PRIVATE c_std_99)
+target_include_directories(test_nwcore_xctype PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_xctype PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_xctype COMMAND test_nwcore_xctype)
diff --git a/tests/core/xctype/test_nwcore_xctype.c b/tests/core/xctype/test_nwcore_xctype.c
new file mode 100644
index 0000000..8153f83
--- /dev/null
+++ b/tests/core/xctype/test_nwcore_xctype.c
@@ -0,0 +1,33 @@
+#include "xCtype.h"
+
+#include <stdio.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  CHECK(LB_tolower('A') == 'a');
+  CHECK(LB_tolower('z') == 'z');
+  CHECK(LB_toupper('a') == 'A');
+  CHECK(LB_toupper('Z') == 'Z');
+
+  CHECK(LB_isalpha('A'));
+  CHECK(LB_isalpha('z'));
+  CHECK(LB_isdigit('7'));
+  CHECK(LB_isxdigit('f'));
+  CHECK(LB_isxdigit('F'));
+  CHECK(LB_isspace(' '));
+  CHECK(LB_isspace('\n'));
+  CHECK(LB_ispunct('.'));
+  CHECK(LB_isprint('~'));
+  CHECK(!LB_isprint('\n'));
+  CHECK(LB_isascii(0x7f));
+  CHECK(!LB_isascii(0x80));
+  return 0;
+}
diff --git a/tests/core/xstring/CMakeLists.txt b/tests/core/xstring/CMakeLists.txt
new file mode 100644
index 0000000..3190ff4
--- /dev/null
+++ b/tests/core/xstring/CMakeLists.txt
@@ -0,0 +1,9 @@
+add_executable(test_nwcore_xstring
+    test_nwcore_xstring.c)
+
+target_compile_features(test_nwcore_xstring PRIVATE c_std_99)
+target_include_directories(test_nwcore_xstring PRIVATE
+    "${CMAKE_SOURCE_DIR}/include/core")
+target_link_libraries(test_nwcore_xstring PRIVATE mars_nwe::core)
+
+add_test(NAME nwcore_xstring COMMAND test_nwcore_xstring)
diff --git a/tests/core/xstring/test_nwcore_xstring.c b/tests/core/xstring/test_nwcore_xstring.c
new file mode 100644
index 0000000..d56b4f3
--- /dev/null
+++ b/tests/core/xstring/test_nwcore_xstring.c
@@ -0,0 +1,39 @@
+#include "xString.h"
+
+#include <stdio.h>
+#include <string.h>
+
+#define CHECK(expr) \
+  do { \
+    if (!(expr)) { \
+      fprintf(stderr, "CHECK failed at %s:%d: %s\n", __FILE__, __LINE__, #expr); \
+      return 1; \
+    } \
+  } while (0)
+
+int main(void)
+{
+  char buffer[32];
+  char overlap[16] = "abcdef";
+
+  CHECK(LB_stricmp("Mars", "mArS") == 0);
+  CHECK(LB_strnicmp("NetWare", "net", 3) == 0);
+  CHECK(LB_memicmp("AbCd", "aBcD", 4) == 0);
+
+  CHECK(LB_strmcpy(buffer, "abcdef", 4) == buffer);
+  CHECK(strcmp(buffer, "abc") == 0);
+
+  strcpy(buffer, "Mars");
+  CHECK(LB_strlwr(buffer) == buffer);
+  CHECK(strcmp(buffer, "mars") == 0);
+  CHECK(LB_strupr(buffer) == buffer);
+  CHECK(strcmp(buffer, "MARS") == 0);
+  CHECK(LB_strrev(buffer) == buffer);
+  CHECK(strcmp(buffer, "SRAM") == 0);
+  CHECK(LB_strset(buffer, 'x') == buffer);
+  CHECK(strcmp(buffer, "xxxx") == 0);
+
+  CHECK(LB_memmove(overlap + 2, overlap, 4) == overlap + 2);
+  CHECK(memcmp(overlap, "ababcd", 6) == 0);
+  return 0;
+}