Match libcmt bounded wide string compare

config/config.json

@@ -914,7 +914,7 @@
 				{ "name": "libs/libcmt/wcspbrk.c", "index": 674, "status": "Matching" },
 				{ "name": "libs/libcmt/wcsnicmp.c", "index": 675, "status": "MISSING" },
 				{ "name": "libs/libcmt/wcsncpy.c", "index": 676, "status": "Matching" },
-				{ "name": "libs/libcmt/wcsncmp.c", "index": 677, "status": "MISSING" },
+				{ "name": "libs/libcmt/wcsncmp.c", "index": 677, "status": "Matching" },
 				{ "name": "libs/libcmt/wcsncat.c", "index": 678, "status": "Matching" },
 				{ "name": "libs/libcmt/wcslwr.c", "index": 679, "status": "MISSING" },
 				{ "name": "libs/libcmt/wcslen.c", "index": 680, "status": "Matching" },

docs/object_matching_logs/libcmt_wcsncmp_obj.md

@@ -0,0 +1,67 @@
+# `libs/libcmt/wcsncmp.obj` exact-match ledger
+
+Historical source was used only as a lead; this lane independently rebuilds
+and validates the complete object against the January target.
+
+## Plain-English behavior and target inventory
+
+`wcsncmp` compares at most `count` UTF-16 characters. A zero count means the
+two spans compare equal. Otherwise it advances while characters are equal and
+nonzero, then returns the unsigned character difference.
+
+- One public function, `_wcsncmp`: 53 target bytes, zero relocations.
+- No target-owned `.data`, `.bss`, or `.rdata`.
+
+## Measured source shapes
+
+| Shape | Measurement | Disposition |
+|---|---|---|
+| Result local and one source return | 53/53 bytes and 0/0 relocs, but different branch topology/register assignment | rejected |
+| Natural CRT early return for `count == 0`, then loop and difference return | Historical lead strict exact; freshly validated below | accepted |
+
+The target has two physical returns. This is a narrow exception to the
+single-return preference: forcing one source return changes codegen and is less
+natural for this standard guard case.
+
+## Fresh current-campaign evidence
+
+The source was transplanted onto campaign tip `b935e2dc` and rebuilt with the
+project-configured XDK 3911 compiler.  The generated command was:
+
+```text
+xbox/bin/vc7/CL.Exe /nologo /c /O1 /Gy /I"xbox/include" \
+  /Fobuild\base\libs\libcmt\wcsncmp.obj libs\libcmt\wcsncmp.c
+```
+
+No lane-local option or build-rule change was used.
+
+| symbol | target | candidate | relocations | normalized SHA-256 | result |
+|---|---:|---:|---:|---|---|
+| `_wcsncmp` | 53 B | 53 B | 0 / 0 | `ededa41b5aab23d5f0e6d5418bde779046e5ea1aeab8ed69b2a9f91793113b9a` | exact |
+
+With no relocations, all 53 runtime code bytes are literally identical.
+`llvm-readobj` confirms one external `_wcsncmp` `.text` COMDAT on both sides.
+The target owns no runtime data or other section; candidate-only directive and
+debug sections are compiler metadata.
+
+## Gates and blast radius
+
+- Complete libcmt build: passed.
+- Complete 467-object Halo build: passed.
+- Progress and semantic progress: passed with zero unit errors.
+- Hardened comparator: `all_equal: true`.
+- Tool tests: 177 / 177 passed.
+
+The implementation adds no shared header or declaration, so its source-level
+blast radius is this one translation unit. Full builds still validate the wider
+projects.
+
+## House/Berth and readability audit
+
+All three parameters are on separate lines. The two returns are the documented
+and measured exception to the single-return preference; a one-return spelling
+changes target codegen. `(void)` formatting is not applicable. The source uses
+no assembly, `volatile`, forced inlining, undefined behavior, byte forcing,
+alignment directive, raw structure offset, comparator exception, or local flag
+workaround. There is no tag/object access requiring typed macros and no
+identified January behavioral bug requiring a preservation note.

libs/libcmt/wcsncmp.c

@@ -0,0 +1,29 @@
+/*
+WCSNCMP.C
+
+symbols in this file:
+	_wcsncmp (.text, 0x35)
+*/
+
+/* ---------- types */
+
+typedef unsigned short wchar_t;
+
+/* ---------- public code */
+
+int __cdecl wcsncmp(
+	wchar_t const *left,
+	wchar_t const *right,
+	unsigned long count)
+{
+	if (!count)
+		return 0;
+
+	while (--count && *left && *left == *right)
+	{
+		left++;
+		right++;
+	}
+
+	return *left - *right;
+}