From dc46d832071174035394795db5e74565928c2dd3 Mon Sep 17 00:00:00 2001
From: khodowany <khodowany@proton.me>
Date: Thu, 8 Oct 2026 02:13:33 -0500
Subject: [PATCH] Cleanup

---
 src/detail/transport_player.hpp |  1 +
 src/transport.cpp               | 13 +++++++++++-
 tests/transport.cpp             | 37 +++++++++++++++++++++++++++++++++
 3 files changed, 50 insertions(+), 1 deletion(-)

diff --git a/src/detail/transport_player.hpp b/src/detail/transport_player.hpp
index f48882f..002d47e 100644
--- a/src/detail/transport_player.hpp
+++ b/src/detail/transport_player.hpp
@@ -16,6 +16,7 @@ struct transport_state {
   std::uint32_t channels{};
   std::uint64_t duration{};
   mutable std::uint64_t cursor{};
+  mutable std::size_t first_live_click{};
   sonus::transport_config config{};
   std::array<std::vector<std::float32_t>, 2> samples{};
   mutable std::vector<std::float32_t> scratch{};
diff --git a/src/transport.cpp b/src/transport.cpp
index b3dc6e7..e4e4797 100644
--- a/src/transport.cpp
+++ b/src/transport.cpp
@@ -155,7 +155,18 @@ auto sonus::detail::transport_player::render(std::float32_t *output, std::uint64
         return;
       }
     }
-    for (auto const &click : state->config.clicks) {
+    // Retain overlapping tails, but never revisit an expired schedule prefix.
+    // The cursor is owned by the render thread and needs no allocation or lock.
+    while (state->first_live_click < state->config.clicks.size()) {
+      auto const &click = state->config.clicks[state->first_live_click];
+      auto length = state->samples[click.downbeat ? 0 : 1].size() / channels;
+      if (click.frame > state->cursor || length > state->cursor - click.frame) {
+        break;
+      }
+      ++state->first_live_click;
+    }
+    for (auto index = state->first_live_click; index < state->config.clicks.size(); ++index) {
+      auto const &click = state->config.clicks[index];
       if (click.frame >= state->cursor + count) {
         break;
       }
diff --git a/tests/transport.cpp b/tests/transport.cpp
index c66860f..eca3536 100644
--- a/tests/transport.cpp
+++ b/tests/transport.cpp
@@ -109,3 +109,40 @@ BOOST_AUTO_TEST_CASE(recording_transport_replacement_cancels_old_session_and_val
   config.clicks.push_back({10, true});
   BOOST_CHECK(!sonus::prepared_transport::create(config, 48000, 2));
 }
+
+BOOST_AUTO_TEST_CASE(recording_transport_long_schedule_preserves_overlaps_across_buffer_sizes) {
+  auto files = recordings{};
+  files.write("beat1.wav", 1537, 1, -1);
+  files.write("beat2.wav", 17, 2, -2);
+  auto config = files.config();
+  config.backing.clear();
+  config.duration_frames = 40000;
+  config.clicks.clear();
+  for (std::uint64_t i = 0; i < 2000; ++i) {
+    config.clicks.push_back({i * 20, i % 7 == 0});
+  }
+  auto expected = std::vector<float>(config.duration_frames * 2);
+  for (auto const &click : config.clicks) {
+    auto length = click.downbeat ? 1537U : 17U;
+    auto value = click.downbeat ? 1.F / 32768 : 2.F / 32768;
+    for (auto frame = click.frame; frame < std::min(click.frame + length, config.duration_frames); ++frame) {
+      expected[frame * 2] += value;
+      expected[frame * 2 + 1] -= value;
+    }
+  }
+  for (auto chunk : {317U, 1024U, 1701U}) {
+    auto prepared = sonus::prepared_transport::create(config, 48000, 2);
+    BOOST_REQUIRE(prepared);
+    auto engine = sonus::engine::create({.sample_rate = 48000, .channels = 2, .master_volume = 1.F, .no_device = true});
+    BOOST_REQUIRE(engine);
+    auto session = engine->play_transport(std::move(*prepared));
+    BOOST_REQUIRE(session);
+    auto actual = std::vector<float>(expected.size());
+    for (std::uint64_t frame = 0; frame < config.duration_frames; frame += chunk) {
+      BOOST_REQUIRE(engine->render(actual.data() + frame * 2, std::min<std::uint64_t>(chunk, config.duration_frames - frame)));
+    }
+    BOOST_CHECK_EQUAL_COLLECTIONS(actual.begin(), actual.end(), expected.begin(), expected.end());
+    BOOST_CHECK(session->status() == sonus::playback_status::COMPLETED);
+    BOOST_TEST(session->frames() == config.duration_frames);
+  }
+}