@@ -31,6 +31,7 @@ enum { REG_MAX_CANDIDATES = 256 };
 #include "foundation/dyn_array.h"
 #include "foundation/platform.h"
 
+#include <ctype.h>
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -465,10 +466,29 @@ bool cbm_suppress_weak_member_match(bool enabled, bool is_method, const char *st
 }
 
 /* A module specifier that names a path inside the indexed tree ("./x", "../x",
- * "/abs/x") rather than an external package. Package specifiers are everything
- * else — "drizzle-orm", "rxjs/operators", "@scope/pkg". */
+ * "/abs/x", and on Windows "C:\x", "C:/x", "\\server\share\x") rather than an
+ * external package. Package specifiers are everything else — "drizzle-orm",
+ * "rxjs/operators", "@scope/pkg". Windows paths must count as in-tree here:
+ * pr-smoke runs this pipeline on Windows, and misclassifying a drive-letter or
+ * UNC specifier as "external" is exactly the false-external edge this guard
+ * exists to prevent (#1355). */
 static bool specifier_is_relative(const char *module_path) {
-    return module_path && (module_path[0] == '.' || module_path[0] == '/');
+    if (!module_path || !module_path[0]) {
+        return false;
+    }
+    if (module_path[0] == '.' || module_path[0] == '/') {
+        return true;
+    }
+    /* UNC share: \\server\share\... */
+    if (module_path[0] == '\\' && module_path[1] == '\\') {
+        return true;
+    }
+    /* Drive-letter absolute path: C:\repo\... or C:/repo/... */
+    if (isalpha((unsigned char)module_path[0]) && module_path[1] == ':' &&
+        (module_path[2] == '\\' || module_path[2] == '/')) {
+        return true;
+    }
+    return false;
 }
 
 static bool import_map_binds(const char **import_map_keys, int import_map_count,
 
@@ -4956,6 +4956,17 @@ static int count_nodes_named(cbm_store_t *s, const char *project, const char *na
  * (axios.get, api.patch on a renamed-axios instance, supertest request(app).get).
  * The regex false edge must stay suppressed in parallel too. CBM_WORKERS forces
  * >1 worker so the parallel path is taken regardless of the host core count. */
+/* #1355: padding count for write_external_import_shadow_fixture, deliberately
+ * well past MIN_FILES_FOR_PARALLEL (=50, a private #define in
+ * src/pipeline/pipeline.c — not exposed to tests, so this cannot be a
+ * static_assert against it) rather than sitting right at the threshold. The
+ * margin, not the exact value, is what the test depends on: a modest bump to
+ * the real threshold must not silently drop this fixture back onto the
+ * sequential-only path and leave the parallel resolver unexercised. Same
+ * pattern as ET_PARALLEL_PAD / CP_PARALLEL_PAD in test_edge_types_probe.c /
+ * test_convergence_probe.c. */
+enum { EXTERNAL_IMPORT_SHADOW_PARALLEL_PAD = 64 };
+
 /* #1355: write the shared external-import-shadow fixture into `dir`.
  * `pad_files` filler modules push the run over MIN_FILES_FOR_PARALLEL so the
  * same tree can be indexed by both resolvers. */
@@ -5046,11 +5057,13 @@ TEST(pipeline_external_import_shadow_not_bound_to_local_homonym_issue1355) {
     /* Enough files that CBM_WORKERS can take the fused-parallel path; the same
      * tree is then indexed by each resolver in turn, because the guard lives at
      * two independent emit sites (pass_calls.c and pass_parallel.c). */
-    write_external_import_shadow_fixture(tmp, 50);
+    write_external_import_shadow_fixture(tmp, EXTERNAL_IMPORT_SHADOW_PARALLEL_PAD);
 
-    char *old_workers = getenv("CBM_WORKERS");
+    /* getenv() returns a pointer into the process environment that must be
+     * treated as read-only; strdup() below only ever reads through it. */
+    const char *old_workers = getenv("CBM_WORKERS");
     char *saved_workers = old_workers ? strdup(old_workers) : NULL;
-    char *old_single = getenv("CBM_INDEX_SINGLE_THREAD");
+    const char *old_single = getenv("CBM_INDEX_SINGLE_THREAD");
     char *saved_single = old_single ? strdup(old_single) : NULL;
 
     cbm_setenv("CBM_INDEX_SINGLE_THREAD", "1", 1);
 
@@ -990,6 +990,39 @@ TEST(external_import_shadow_relative_binding_wins_the_tie) {
     PASS();
 }
 
+TEST(external_import_shadow_windows_relative_specifier_kept) {
+    /* #1355 follow-up: a Windows-style specifier —
+     * drive-letter absolute (`C:\...` / `C:/...`) or UNC share (`\\server\...`)
+     * — names a path inside the indexed tree exactly like a POSIX "./x" or
+     * "/x". pr-smoke runs this pipeline on Windows; before this fix these
+     * specifiers fell through to "external package" and the same-name guess
+     * they'd otherwise validate got suppressed on that platform only. */
+    CBMImport imports[] = {
+        {.local_name = "eq", .module_path = "C:\\repo\\src\\text-utils.ts"},
+        {.local_name = "sql", .module_path = "C:/repo/src/text-utils.ts"},
+        {.local_name = "normalize", .module_path = "\\\\server\\share\\text-utils.ts"},
+    };
+    CBMImportArray arr = {.items = imports, .count = 3, .cap = 3};
+
+    /* None of these materialized an import-map key (as if resolution missed
+     * them, mirroring the reported scenario) — the specifier alone must still
+     * keep the edge because it is in-tree, not external. RED before the fix
+     * (specifier_is_relative saw '.' / '/' only, so all three were classified
+     * external and suppressed); GREEN after. */
+    ASSERT_FALSE(cbm_suppress_external_import_shadow("eq", "unique_name", &arr, NULL, 0));
+    ASSERT_FALSE(cbm_suppress_external_import_shadow("sql", "unique_name", &arr, NULL, 0));
+    ASSERT_FALSE(cbm_suppress_external_import_shadow("normalize", "unique_name", &arr, NULL, 0));
+    /* A bare package specifier without any drive letter or leading separator
+     * (e.g. "drizzle-orm") must still be external — this predicate must not
+     * become "anything with a colon or backslash". */
+    CBMImport pkg_only[] = {
+        {.local_name = "eq", .module_path = "drizzle-orm"},
+    };
+    CBMImportArray parr = {.items = pkg_only, .count = 1, .cap = 1};
+    ASSERT_TRUE(cbm_suppress_external_import_shadow("eq", "unique_name", &parr, NULL, 0));
+    PASS();
+}
+
 /* ── Suite ─────────────────────────────────────────────────────── */
 
 /* Method call THROUGH an imported symbol that is itself an indexed node
@@ -1089,4 +1122,5 @@ SUITE(registry) {
     RUN_TEST(external_import_shadow_drops_package_bound_bare_call);
     RUN_TEST(external_import_shadow_keeps_everything_else);
     RUN_TEST(external_import_shadow_relative_binding_wins_the_tie);
+    RUN_TEST(external_import_shadow_windows_relative_specifier_kept);
 }