fix: normalize mixed path separators to forward slashes on Windows (#146)

Adds `cbm_normalize_path_sep()` to platform.h — converts backslash to
forward slash on Windows, no-op on POSIX. Applied at entry points:
- `cbm_get_home_dir()` — HOME/USERPROFILE paths
- `handle_index_repository()` — repo_path argument
- `build_snippet_response()` — _fullpath results
- FQN computation — replaces inline loops

Thanks @jimpark for the clean, focused fix!

Author: jimpark

src/foundation/platform.c

@@ -97,6 +97,17 @@ int64_t cbm_file_size(const char *path) {
     return (int64_t)sz.QuadPart;
 }
 
+char *cbm_normalize_path_sep(char *path) {
+    if (path) {
+        for (char *p = path; *p; p++) {
+            if (*p == '\\') {
+                *p = '/';
+            }
+        }
+    }
+    return path;
+}
+
 #else /* POSIX (macOS + Linux) */
 
 /* ── POSIX implementation ─────────────────────────────────────── */
@@ -215,20 +226,31 @@ int64_t cbm_file_size(const char *path) {
     return (int64_t)st.st_size;
 }
 
+char *cbm_normalize_path_sep(char *path) {
+    /* No-op on POSIX — paths already use forward slashes. */
+    (void)path;
+    return path;
+}
+
 #endif /* _WIN32 */
 
 /* ── Home directory (cross-platform) ──────────────────────────── */
 
 const char *cbm_get_home_dir(void) {
+    static char buf[1024];
     // NOLINTNEXTLINE(concurrency-mt-unsafe)
     const char *h = getenv("HOME");
     if (h && h[0]) {
-        return h;
+        snprintf(buf, sizeof(buf), "%s", h);
+        cbm_normalize_path_sep(buf);
+        return buf;
     }
     // NOLINTNEXTLINE(concurrency-mt-unsafe)
     h = getenv("USERPROFILE");
     if (h && h[0]) {
-        return h;
+        snprintf(buf, sizeof(buf), "%s", h);
+        cbm_normalize_path_sep(buf);
+        return buf;
     }
     return NULL;
 }

src/foundation/platform.h

@@ -81,4 +81,9 @@ bool cbm_is_dir(const char *path);
 /* Get file size. Returns -1 on error. */
 int64_t cbm_file_size(const char *path);
 
+/* Normalize path separators to forward slashes (in-place).
+ * On Windows, converts backslashes to forward slashes.
+ * On POSIX, this is a no-op. Returns the input pointer. */
+char *cbm_normalize_path_sep(char *path);
+
 #endif /* CBM_PLATFORM_H */

src/mcp/mcp.c

@@ -1423,6 +1423,7 @@ static char *get_project_root(cbm_mcp_server_t *srv, const char *project) {
 static char *handle_index_repository(cbm_mcp_server_t *srv, const char *args) {
     char *repo_path = cbm_mcp_get_string_arg(args, "repo_path");
     char *mode_str = cbm_mcp_get_string_arg(args, "mode");
+    cbm_normalize_path_sep(repo_path);
 
     if (!repo_path) {
         free(mode_str);
@@ -1584,13 +1585,14 @@ static char *build_snippet_response(cbm_mcp_server_t *srv, cbm_node_t *node,
 #ifdef _WIN32
         if (_fullpath(real_root, root_path, sizeof(real_root)) &&
             _fullpath(real_file, abs_path, sizeof(real_file))) {
+            cbm_normalize_path_sep(real_root);
+            cbm_normalize_path_sep(real_file);
 #else
         if (realpath(root_path, real_root) && realpath(abs_path, real_file)) {
 #endif
             size_t root_len = strlen(real_root);
             if (strncmp(real_file, real_root, root_len) == 0 &&
-                (real_file[root_len] == '/' || real_file[root_len] == '\\' ||
-                 real_file[root_len] == '\0')) {
+                (real_file[root_len] == '/' || real_file[root_len] == '\0')) {
                 path_ok = true;
             }
         }

src/pipeline/fqn.c

@@ -5,6 +5,7 @@
  * Handles Python __init__.py, JS/TS index.{js,ts}, path separators.
  */
 #include "pipeline/pipeline.h"
+#include "foundation/platform.h"
 
 #include <stddef.h> // NULL
 #include <stdio.h>
@@ -58,12 +59,8 @@ char *cbm_pipeline_fqn_compute(const char *project, const char *rel_path, const
     /* Work on a mutable copy for path manipulation */
     char *path = strdup(rel_path ? rel_path : "");
 
-    /* Convert backslash to forward slash */
-    for (char *p = path; *p; p++) {
-        if (*p == '\\') {
-            *p = '/';
-        }
-    }
+    /* Normalize path separators */
+    cbm_normalize_path_sep(path);
 
     /* Strip file extension */
     {
@@ -136,11 +133,7 @@ char *cbm_pipeline_fqn_folder(const char *project, const char *rel_dir) {
 
     /* Work on mutable copy */
     char *dir = strdup(rel_dir ? rel_dir : "");
-    for (char *p = dir; *p; p++) {
-        if (*p == '\\') {
-            *p = '/';
-        }
-    }
+    cbm_normalize_path_sep(dir);
 
     const char *segments[256];
     int seg_count = 0;
@@ -174,12 +167,8 @@ char *cbm_project_name_from_path(const char *abs_path) {
     char *path = strdup(abs_path);
     size_t len = strlen(path);
 
-    /* Convert \ to / */
-    for (size_t i = 0; i < len; i++) {
-        if (path[i] == '\\') {
-            path[i] = '/';
-        }
-    }
+    /* Normalize path separators */
+    cbm_normalize_path_sep(path);
 
     /* Replace / and : with - */
     for (size_t i = 0; i < len; i++) {