Remove dead code and empty files; widen CLI selftest coverage

- Drop Rice::compute_k: it has no callers and used a float k estimator
  inconsistent with the live integer Rice::adapt_k.
- Delete empty placeholder files and remove them from CMake:
  bit_reader.cpp and logger.cpp (both header-only) and endian.hpp (unused).
- Expand `lac_cli selftest` to also round-trip mono and per-block/auto
  stereo (mode 2), and document why the selftest stays in the CLI.

The dead Encoder `order` parameter is intentionally left for #25, where the
encoder constructors are reworked; removing it now would shift arguments
across ~15 call sites in a way that compiles silently.

Refs #30

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: audexdev

CMakeLists.txt

@@ -11,7 +11,6 @@ set(LAC_TEST_ASSETS_DIR "${PROJECT_BINARY_DIR}/lac-test-assets" CACHE PATH "Opti
 find_package(Threads REQUIRED)
 
 add_library(lac STATIC
-    src/codec/bitstream/bit_reader.cpp
     src/codec/bitstream/bit_writer.cpp
     src/codec/block/decoder.cpp
     src/codec/block/encoder.cpp
@@ -21,7 +20,6 @@ add_library(lac STATIC
     src/codec/rice/rice.cpp
     src/codec/simd/neon.cpp
     src/io/wav_io.cpp
-    src/utils/logger.cpp
 
     src/codec/bitstream/bit_reader.hpp
     src/codec/bitstream/bit_writer.hpp
@@ -37,7 +35,6 @@ add_library(lac STATIC
     src/codec/rice/rice.hpp
     src/codec/simd/neon.hpp
     src/io/wav_io.hpp
-    src/utils/endian.hpp
     src/utils/logger.hpp
     include/lac/lac.hpp
     include/lac/version.hpp

src/codec/bitstream/bit_reader.cpp

@@ -47,22 +47,3 @@ bool Rice::decode(BitReader& r, uint32_t k, int32_t& value) {
     value = unsigned_to_signed(u);
     return true;
 }
-
-uint32_t Rice::compute_k(const std::vector<int32_t>& residuals) {
-    uint64_t sum = 0;
-    for (int32_t v : residuals) {
-        uint32_t u = signed_to_unsigned(v);
-        sum += u;
-    }
-
-    if (residuals.empty()) return 0;
-
-    double mean = double(sum) / double(residuals.size());
-
-    uint32_t k = 0;
-    while ((1u << k) < (uint32_t)(mean + 0.5) && k < 31) {
-        k++;
-    }
-
-    return k;
-}

src/codec/rice/rice.cpp

@@ -35,9 +35,6 @@ class Rice {
 
     static bool decode(BitReader& r, uint32_t k, int32_t& value);
 
-    // Compute optimal k from residual block
-    static uint32_t compute_k(const std::vector<int32_t>& residuals);
-
     static uint32_t adapt_k(uint64_t sum, uint32_t count, AdaptState& state);
 
 private:

src/codec/rice/rice.hpp

@@ -792,6 +792,8 @@ int main(int argc, char** argv) {
     }
 
     if (mode == "selftest") {
+      // Kept in the CLI on purpose: CI runs `lac_cli selftest` as a build-time
+      // smoke test, and it gives end users a dependency-free roundtrip check.
       const double pi = 3.14159265358979323846;
       constexpr int32_t pcm24_max = 0x7FFFFF;
 
@@ -847,6 +849,37 @@ int main(int argc, char** argv) {
           return false;
         }
 
+        // Per-block (auto) stereo, stereo_mode 2.
+        LAC::Encoder enc_auto(12, 2, sample_rate, bit_depth);
+        std::vector<uint8_t> bs_auto = enc_auto.encode(src_left, src_right);
+        std::vector<int32_t> dec_auto_left, dec_auto_right;
+        FrameHeader hdr_auto;
+        decoder.decode(bs_auto.data(), bs_auto.size(), dec_auto_left, dec_auto_right, &hdr_auto);
+        if (dec_auto_left != src_left || dec_auto_right != src_right) {
+          std::cerr << "Auto-stereo roundtrip mismatch for sr=" << sample_rate << " depth=" << int(bit_depth) << "\n";
+          return false;
+        }
+        if (hdr_auto.stereo_mode != 2) {
+          std::cerr << "Auto-stereo header mismatch stereo_mode=" << int(hdr_auto.stereo_mode) << "\n";
+          return false;
+        }
+
+        // Mono.
+        std::vector<int32_t> empty_right;
+        LAC::Encoder enc_mono(12, 0, sample_rate, bit_depth);
+        std::vector<uint8_t> bs_mono = enc_mono.encode(src_left, empty_right);
+        std::vector<int32_t> dec_mono_left, dec_mono_right;
+        FrameHeader hdr_mono;
+        decoder.decode(bs_mono.data(), bs_mono.size(), dec_mono_left, dec_mono_right, &hdr_mono);
+        if (dec_mono_left != src_left || !dec_mono_right.empty()) {
+          std::cerr << "Mono roundtrip mismatch for sr=" << sample_rate << " depth=" << int(bit_depth) << "\n";
+          return false;
+        }
+        if (hdr_mono.channels != 1) {
+          std::cerr << "Mono header mismatch channels=" << int(hdr_mono.channels) << "\n";
+          return false;
+        }
+
         auto lr_us = std::chrono::duration_cast<std::chrono::microseconds>(t1 - t0).count();
         auto ms_us = std::chrono::duration_cast<std::chrono::microseconds>(t3 - t2).count();
         bool ms_smaller = bs_ms.size() < bs_lr.size();