diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index d4dfc086..189a3a74 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -298,6 +298,7 @@ else()
       add_extra_test(upsert_alldups SOURCE extra/upsert_alldups.c)
       add_extra_test(dupfix_addodd SOURCE extra/dupfix_addodd.c)
     endif()
+    add_extra_test(details_rkl SOURCE extra/details_rkl.c)
     if(MDBX_BUILD_CXX)
       if(NOT WIN32 OR NOT MDBX_CXX_STANDARD LESS 17)
         add_extra_test(cursor_closing)
diff --git a/test/extra/details_rkl.c b/test/extra/details_rkl.c
new file mode 100644
index 00000000..49ef0428
--- /dev/null
+++ b/test/extra/details_rkl.c
@@ -0,0 +1,248 @@
+/// \copyright SPDX-License-Identifier: Apache-2.0
+/// \author Леонид Юрьев aka Leonid Yuriev <leo@yuriev.ru> \date 2025
+
+#define debug_log debug_log_sub
+
+#include "../../src/rkl.c"
+#include "../../src/txl.c"
+
+MDBX_MAYBE_UNUSED __cold void debug_log_sub(int level, const char *function, int line, const char *fmt, ...) {
+  (void)level;
+  (void)function;
+  (void)line;
+  (void)fmt;
+}
+
+/*-----------------------------------------------------------------------------*/
+
+static size_t tst_failed, tst_ok, tst_iterations, tst_cases;
+#ifndef NDEBUG
+static size_t tst_target;
+#endif
+
+static bool check_bool(bool v, bool expect, const char *fn, unsigned line) {
+  if (unlikely(v != expect)) {
+    ++tst_failed;
+    fprintf(stderr, "iteration %zi: got %s, expected %s, at %s:%u\n", tst_iterations, v ? "true" : "false",
+            expect ? "true" : "false", fn, line);
+    fflush(nullptr);
+    return false;
+  }
+  ++tst_ok;
+  return true;
+}
+
+static bool check_eq(uint64_t v, uint64_t expect, const char *fn, unsigned line) {
+  if (unlikely(v != expect)) {
+    ++tst_failed;
+    fprintf(stderr, "iteration %zi: %" PRIu64 " (got) != %" PRIu64 " (expected), at %s:%u\n", tst_iterations, v, expect,
+            fn, line);
+    fflush(nullptr);
+    return false;
+  }
+  ++tst_ok;
+  return true;
+}
+
+#define CHECK_BOOL(T, EXPECT) check_bool((T), (EXPECT), __func__, __LINE__)
+#define CHECK_TRUE(T) CHECK_BOOL(T, true)
+#define CHECK_FALSE(T) CHECK_BOOL(T, false)
+#define CHECK_EQ(T, EXPECT) check_eq((T), (EXPECT), __func__, __LINE__)
+
+void trivia(void) {
+  rkl_t x, y;
+
+  rkl_init(&x);
+  rkl_init(&y);
+  CHECK_TRUE(rkl_check(&x));
+  CHECK_TRUE(rkl_empty(&x));
+  CHECK_EQ(rkl_len(&x), 0);
+
+  rkl_iterator_t f, r;
+  rkl_iterator_init(&f, &x, false);
+  rkl_iterator_init(&r, &x, true);
+  CHECK_EQ(rkl_iterator_left(&f, &x, false), 0);
+  CHECK_EQ(rkl_iterator_left(&f, &x, true), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &x, false), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &x, true), 0);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, false), 0);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, true), 0);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, false), 0);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, true), 0);
+  CHECK_TRUE(rkl_check(&x));
+
+  CHECK_EQ(rkl_push(&x, 42, false), MDBX_SUCCESS);
+  CHECK_TRUE(rkl_check(&x));
+  CHECK_FALSE(rkl_empty(&x));
+  CHECK_EQ(rkl_len(&x), 1);
+  CHECK_TRUE(rkl_push(&x, 42, true) == MDBX_RESULT_TRUE);
+  CHECK_TRUE(rkl_check(&x));
+
+  rkl_iterator_init(&f, &x, false);
+  rkl_iterator_init(&r, &x, true);
+  CHECK_EQ(rkl_iterator_left(&f, &x, false), 1);
+  CHECK_EQ(rkl_iterator_left(&f, &x, true), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &x, false), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &x, true), 1);
+
+  CHECK_EQ(rkl_iterator_turn(&f, &x, true), 0);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, false), 42);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, false), 0);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, true), 42);
+  CHECK_EQ(rkl_iterator_turn(&f, &x, true), 0);
+
+  CHECK_EQ(rkl_iterator_turn(&r, &x, false), 0);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, true), 42);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, true), 0);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, false), 42);
+  CHECK_EQ(rkl_iterator_turn(&r, &x, false), 0);
+
+  rkl_resize(&x, 222);
+  CHECK_FALSE(rkl_empty(&x));
+  CHECK_TRUE(rkl_check(&x));
+
+  rkl_destructive_move(&x, &y);
+  CHECK_TRUE(rkl_check(&x));
+  CHECK_TRUE(rkl_check(&y));
+  rkl_destroy(&x);
+  rkl_destroy(&y);
+}
+
+/*-----------------------------------------------------------------------------*/
+
+uint64_t prng;
+
+static bool stochastic_pass(const unsigned start, const unsigned width, const unsigned n) {
+  rkl_t k, c;
+  txl_t l = txl_alloc();
+  if (!CHECK_TRUE(l))
+    return false;
+
+  rkl_init(&k);
+  rkl_init(&c);
+  const size_t errors = tst_failed;
+
+  rkl_iterator_t f, r;
+  rkl_iterator_init(&f, &k, false);
+  rkl_iterator_init(&r, &k, true);
+
+  txnid_t lowest = UINT_MAX;
+  txnid_t highest = 0;
+  while (MDBX_PNL_GETSIZE(l) < n) {
+    prng = prng * UINT64_C(6364136223846793005) + 1;
+    txnid_t id = (txnid_t)(prng % width + start);
+    if (id < MIN_TXNID || id >= INVALID_TXNID)
+      continue;
+    if (txl_contain(l, id)) {
+      if (!CHECK_TRUE(rkl_contain(&k, id)) || !CHECK_TRUE(rkl_push(&k, id, false) == MDBX_RESULT_TRUE))
+        break;
+      continue;
+    }
+    if (!CHECK_FALSE(rkl_contain(&k, id)))
+      break;
+
+    if (tst_iterations % (1u << 24) == 0 && tst_iterations) {
+      printf("done %.3fM iteration, %zu cases\n", tst_iterations / 1000000.0, tst_cases);
+      fflush(nullptr);
+    }
+    tst_iterations += 1;
+
+#ifndef NDEBUG
+    if (tst_iterations == tst_target) {
+      printf("reach %zu iteration\n", tst_iterations);
+      fflush(nullptr);
+    }
+#endif
+
+    if (!CHECK_EQ(rkl_push(&k, id, false), MDBX_SUCCESS))
+      break;
+    if (!CHECK_TRUE(rkl_check(&k)))
+      break;
+    if (!CHECK_EQ(txl_append(&l, id), MDBX_SUCCESS))
+      break;
+    if (!CHECK_TRUE(rkl_contain(&k, id)))
+      break;
+
+    lowest = (lowest < id) ? lowest : id;
+    highest = (highest > id) ? highest : id;
+    if (!CHECK_EQ(rkl_lowest(&k), lowest))
+      break;
+    if (!CHECK_EQ(rkl_highest(&k), highest))
+      break;
+  }
+
+  txl_sort(l);
+  CHECK_EQ(rkl_len(&k), n);
+  CHECK_EQ(MDBX_PNL_GETSIZE(l), n);
+
+  rkl_iterator_init(&f, &k, false);
+  rkl_iterator_init(&r, &k, true);
+  CHECK_EQ(rkl_iterator_left(&f, &k, false), n);
+  CHECK_EQ(rkl_iterator_left(&f, &k, true), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &k, false), 0);
+  CHECK_EQ(rkl_iterator_left(&r, &k, true), n);
+
+  for (size_t i = 0; i < n; ++i) {
+    CHECK_EQ(rkl_iterator_turn(&f, &k, false), l[n - i]);
+    CHECK_EQ(rkl_iterator_left(&f, &k, false), n - i - 1);
+    CHECK_EQ(rkl_iterator_left(&f, &k, true), i + 1);
+
+    CHECK_EQ(rkl_iterator_turn(&r, &k, true), l[i + 1]);
+    r.pos += 1;
+    CHECK_EQ(rkl_iterator_turn(&r, &k, true), l[i + 1]);
+    CHECK_EQ(rkl_iterator_left(&r, &k, true), n - i - 1);
+    CHECK_EQ(rkl_iterator_left(&r, &k, false), i + 1);
+  }
+
+  if (CHECK_EQ(rkl_copy(&k, &c), MDBX_SUCCESS)) {
+    for (size_t i = 1; i <= n; ++i) {
+      if (!CHECK_FALSE(rkl_empty(&k)))
+        break;
+      if (!CHECK_FALSE(rkl_empty(&c)))
+        break;
+      CHECK_EQ(rkl_pop(&k, true), l[i]);
+      CHECK_EQ(rkl_pop(&c, false), l[1 + n - i]);
+    }
+  }
+
+  CHECK_TRUE(rkl_empty(&k));
+  CHECK_TRUE(rkl_empty(&c));
+
+  rkl_destroy(&k);
+  rkl_destroy(&c);
+  txl_free(l);
+
+  ++tst_cases;
+  return errors == tst_failed;
+}
+
+static bool stochastic(const size_t limit_cases, const size_t limit_loops) {
+  for (unsigned loop = 0; tst_cases < limit_cases || loop < limit_loops; ++loop)
+    for (unsigned width = 2; width < 10; ++width)
+      for (unsigned n = 1; n < width; ++n)
+        for (unsigned prev = 1, start = 0, t; start < 4242; t = start + prev, prev = start, start = t)
+          if (!stochastic_pass(start, 1u << width, 1u << n) || tst_failed > 42) {
+            puts("bailout\n");
+            return false;
+          }
+  return true;
+}
+
+int main(int argc, const char *argv[]) {
+  (void)argc;
+  (void)argv;
+
+#ifndef NDEBUG
+  // tst_target = 281870;
+#endif
+  prng = (uint64_t)time(nullptr);
+  printf("prng-seed %" PRIu64 "\n", prng);
+  fflush(nullptr);
+
+  trivia();
+  stochastic(42 * 42 * 42, 42);
+  printf("done: %zu cases, %zu iterations, %zu checks ok, %zu checks failed\n", tst_cases, tst_iterations, tst_ok,
+         tst_failed);
+  fflush(nullptr);
+  return tst_failed ? EXIT_FAILURE : EXIT_SUCCESS;
+}