fix(extract): drop cgo's import "C" pseudo-package

internal/cbm/extract_imports.c

@@ -133,6 +133,19 @@ static void parse_go_import_spec(CBMExtractCtx *ctx, TSNode spec) {
         return;
     }
 
+    /* cgo: `import "C"` names the cgo PSEUDO-package, not a real one — "C" is
+     * reserved by go/build and no package with that import path can exist.
+     * Emitting it as an ordinary import makes the import resolver fall through
+     * to its symbol-name fallback (cbm_pipeline_resolve_import_node Strategy 3,
+     * pass_pkgmap.c), which matches the literal name "C" against every project
+     * node called C and picks the lexicographically smallest: on a real Go repo
+     * all 27 cgo files pointed their IMPORTS edge at the same unrelated `C`
+     * member of a test helper. Drop it — the C side is not a graph package, and
+     * the file's remaining imports are unaffected. */
+    if (strcmp(path, "C") == 0) {
+        return;
+    }
+
     TSNode name_node = ts_node_child_by_field_name(spec, TS_FIELD("name"));
     const char *local_name =
         !ts_node_is_null(name_node) ? cbm_node_text(a, name_node, ctx->source) : path_last(a, path);

tests/test_extraction.c

@@ -2865,6 +2865,25 @@ TEST(go_imports) {
     PASS();
 }
 
+/* cgo's `import "C"` is a pseudo-package, not a real import: keeping it lets the
+ * import resolver name-match "C" onto an arbitrary project symbol called C. The
+ * real imports of the same file must survive. */
+TEST(go_cgo_pseudo_import_dropped) {
+    CBMFileResult *r = extract("package m\n\n/*\nstatic int helper(void) { return 1; }\n*/\n"
+                               "import \"C\"\n\nimport \"fmt\"\n\n"
+                               "func Run() { fmt.Println(C.helper()) }\n",
+                               CBM_LANG_GO, "t", "cgo.go");
+    ASSERT_NOT_NULL(r);
+    ASSERT_FALSE(r->has_error);
+    ASSERT(has_import(r, "fmt"));
+    for (int i = 0; i < r->imports.count; i++) {
+        ASSERT_NOT_NULL(r->imports.items[i].module_path);
+        ASSERT_TRUE(strcmp(r->imports.items[i].module_path, "C") != 0);
+    }
+    cbm_free_result(r);
+    PASS();
+}
+
 TEST(java_imports) {
     CBMFileResult *r = extract(
         "import java.util.List;\nimport java.util.ArrayList;\nimport static java.lang.Math.PI;\n"
@@ -6543,6 +6562,7 @@ SUITE(extraction) {
     RUN_TEST(python_imports);
     RUN_TEST(js_imports);
     RUN_TEST(go_imports);
+    RUN_TEST(go_cgo_pseudo_import_dropped);
     RUN_TEST(java_imports);
     RUN_TEST(rust_imports);
     RUN_TEST(c_imports);