diff --git a/backend/cpp/audio-cpp/CMakeLists.txt b/backend/cpp/audio-cpp/CMakeLists.txt
new file mode 100644
index 000000000..42e4e564a
--- /dev/null
+++ b/backend/cpp/audio-cpp/CMakeLists.txt
@@ -0,0 +1,70 @@
+# SPDX-License-Identifier: MIT
+
+cmake_minimum_required(VERSION 3.20)
+project(audio-cpp-grpc-server LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+set(AUDIO_CPP_DIR "${CMAKE_CURRENT_SOURCE_DIR}/audio.cpp"
+    CACHE PATH "Path to the audio.cpp source tree")
+set(LOCALAI_BACKEND_PROTO "${CMAKE_CURRENT_SOURCE_DIR}/../../backend.proto"
+    CACHE FILEPATH "Path to the LocalAI backend protocol")
+
+option(ENGINE_ENABLE_CUDA "Build audio.cpp with CUDA support" OFF)
+option(ENGINE_ENABLE_VULKAN "Build audio.cpp with Vulkan support" OFF)
+option(ENGINE_ENABLE_METAL "Build audio.cpp with Metal support" OFF)
+
+find_package(Protobuf CONFIG REQUIRED)
+find_package(gRPC CONFIG REQUIRED)
+find_program(PROTOC_EXECUTABLE NAMES protoc REQUIRED)
+find_program(GRPC_CPP_PLUGIN_EXECUTABLE NAMES grpc_cpp_plugin REQUIRED)
+
+get_filename_component(LOCALAI_BACKEND_PROTO_DIR
+    "${LOCALAI_BACKEND_PROTO}" DIRECTORY)
+set(LOCALAI_PROTO_SOURCES
+    "${CMAKE_CURRENT_BINARY_DIR}/backend.pb.cc"
+    "${CMAKE_CURRENT_BINARY_DIR}/backend.grpc.pb.cc")
+set(LOCALAI_PROTO_HEADERS
+    "${CMAKE_CURRENT_BINARY_DIR}/backend.pb.h"
+    "${CMAKE_CURRENT_BINARY_DIR}/backend.grpc.pb.h")
+
+add_custom_command(
+    OUTPUT ${LOCALAI_PROTO_SOURCES} ${LOCALAI_PROTO_HEADERS}
+    COMMAND "${PROTOC_EXECUTABLE}"
+    ARGS
+      --cpp_out "${CMAKE_CURRENT_BINARY_DIR}"
+      --grpc_out "${CMAKE_CURRENT_BINARY_DIR}"
+      -I "${LOCALAI_BACKEND_PROTO_DIR}"
+      --plugin=protoc-gen-grpc="${GRPC_CPP_PLUGIN_EXECUTABLE}"
+      "${LOCALAI_BACKEND_PROTO}"
+    DEPENDS "${LOCALAI_BACKEND_PROTO}"
+    VERBATIM)
+
+add_library(localai_backend_proto STATIC
+    ${LOCALAI_PROTO_SOURCES}
+    ${LOCALAI_PROTO_HEADERS})
+target_include_directories(localai_backend_proto
+    PUBLIC "${CMAKE_CURRENT_BINARY_DIR}")
+target_link_libraries(localai_backend_proto
+    PUBLIC protobuf::libprotobuf gRPC::grpc++)
+
+if(NOT EXISTS "${AUDIO_CPP_DIR}/CMakeLists.txt")
+  message(FATAL_ERROR
+      "AUDIO_CPP_DIR does not point to an audio.cpp source tree: ${AUDIO_CPP_DIR}")
+endif()
+add_subdirectory("${AUDIO_CPP_DIR}" "${CMAKE_CURRENT_BINARY_DIR}/audio.cpp")
+
+# Task 2 replaces this generated entry point with the LocalAI service.
+set(AUDIO_CPP_SERVER_PLACEHOLDER
+    "${CMAKE_CURRENT_BINARY_DIR}/audio-cpp-grpc-server-placeholder.cpp")
+file(GENERATE OUTPUT "${AUDIO_CPP_SERVER_PLACEHOLDER}"
+    CONTENT "int main() { return 0; }\n")
+
+add_executable(audio-cpp-grpc-server "${AUDIO_CPP_SERVER_PLACEHOLDER}")
+target_link_libraries(audio-cpp-grpc-server PRIVATE
+    engine_runtime
+    localai_backend_proto
+    gRPC::grpc++
+    gRPC::grpc++_reflection)
diff --git a/backend/cpp/audio-cpp/Makefile b/backend/cpp/audio-cpp/Makefile
new file mode 100644
index 000000000..b474d3fe5
--- /dev/null
+++ b/backend/cpp/audio-cpp/Makefile
@@ -0,0 +1,58 @@
+# SPDX-License-Identifier: MIT
+
+AUDIO_CPP_VERSION?=f8fb0c19739193adfad0d9e58da99f25eda65256
+AUDIO_CPP_REPO?=https://github.com/0xShug0/audio.cpp
+AUDIO_CPP_SRC?=
+
+CURRENT_MAKEFILE_DIR := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
+BUILD_DIR := build
+
+BUILD_TYPE ?=
+JOBS ?= $(shell nproc 2>/dev/null || sysctl -n hw.ncpu 2>/dev/null || echo 4)
+UNAME_S := $(shell uname -s)
+
+CMAKE_ARGS ?= -DCMAKE_BUILD_TYPE=Release
+CMAKE_ARGS += -DENGINE_ENABLE_CUDA=OFF
+CMAKE_ARGS += -DENGINE_ENABLE_VULKAN=OFF
+CMAKE_ARGS += -DENGINE_ENABLE_METAL=OFF
+
+ifeq ($(BUILD_TYPE),cublas)
+	CMAKE_ARGS += -DENGINE_ENABLE_CUDA=ON
+else ifeq ($(BUILD_TYPE),vulkan)
+	CMAKE_ARGS += -DENGINE_ENABLE_VULKAN=ON
+else ifeq ($(UNAME_S),Darwin)
+	CMAKE_ARGS += -DENGINE_ENABLE_METAL=ON
+endif
+
+.PHONY: all grpc-server test clean purge
+
+all: grpc-server
+
+audio.cpp:
+ifneq ($(AUDIO_CPP_SRC),)
+	ln -sfn $(abspath $(AUDIO_CPP_SRC)) audio.cpp
+else
+	mkdir -p audio.cpp
+	cd audio.cpp && \
+	git init -q && \
+	git remote add origin $(AUDIO_CPP_REPO) && \
+	git fetch --depth 1 origin $(AUDIO_CPP_VERSION) && \
+	git checkout --detach FETCH_HEAD && \
+	git submodule update --init --recursive --depth 1
+endif
+
+grpc-server: audio.cpp
+	mkdir -p $(BUILD_DIR)
+	cd $(BUILD_DIR) && cmake $(CMAKE_ARGS) $(CURRENT_MAKEFILE_DIR)
+	cmake --build $(BUILD_DIR) --config Release \
+		--target audio-cpp-grpc-server -j $(JOBS)
+	cp $(BUILD_DIR)/audio-cpp-grpc-server grpc-server
+
+test:
+	bash tests/build_contract_test.sh
+
+clean:
+	rm -rf $(BUILD_DIR) grpc-server
+
+purge: clean
+	rm -rf audio.cpp
diff --git a/backend/cpp/audio-cpp/tests/build_contract_test.sh b/backend/cpp/audio-cpp/tests/build_contract_test.sh
new file mode 100755
index 000000000..02df3fba1
--- /dev/null
+++ b/backend/cpp/audio-cpp/tests/build_contract_test.sh
@@ -0,0 +1,164 @@
+#!/usr/bin/env bash
+# SPDX-License-Identifier: MIT
+
+set -euo pipefail
+
+backend_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+tmp_dir="$(mktemp -d)"
+trap 'rm -rf "${tmp_dir}"' EXIT
+
+fixture_dir="${tmp_dir}/audio.cpp"
+prefix_dir="${tmp_dir}/prefix"
+tools_dir="${tmp_dir}/tools"
+mkdir -p "${fixture_dir}" "${prefix_dir}/lib/cmake/Protobuf" \
+  "${prefix_dir}/lib/cmake/gRPC" "${tools_dir}"
+
+cat >"${fixture_dir}/engine_runtime.cpp" <<'EOF'
+void audio_cpp_build_contract_fixture() {}
+EOF
+
+cat >"${fixture_dir}/CMakeLists.txt" <<'EOF'
+cmake_minimum_required(VERSION 3.20)
+project(AudioCppBuildContractFixture LANGUAGES CXX)
+
+option(ENGINE_ENABLE_CUDA "Build with CUDA" OFF)
+option(ENGINE_ENABLE_VULKAN "Build with Vulkan" OFF)
+option(ENGINE_ENABLE_METAL "Build with Metal" OFF)
+
+foreach(wrong_option IN ITEMS
+    AUDIO_CPP_ENABLE_CUDA
+    AUDIO_CPP_ENABLE_VULKAN
+    AUDIO_CPP_ENABLE_METAL
+    AUDIOCPP_ENABLE_CUDA
+    AUDIOCPP_ENABLE_VULKAN
+    AUDIOCPP_ENABLE_METAL
+    ENGINE_CUDA
+    ENGINE_VULKAN
+    ENGINE_METAL
+    GGML_CUDA
+    GGML_VULKAN
+    GGML_METAL)
+  if(DEFINED ${wrong_option})
+    message(FATAL_ERROR "legacy or unsupported audio.cpp option: ${wrong_option}")
+  endif()
+endforeach()
+
+add_library(engine_runtime STATIC engine_runtime.cpp)
+EOF
+
+cat >"${prefix_dir}/lib/cmake/Protobuf/ProtobufConfig.cmake" <<'EOF'
+set(Protobuf_FOUND TRUE)
+set(Protobuf_VERSION 0.0.0)
+if(NOT TARGET protobuf::libprotobuf)
+  add_library(protobuf::libprotobuf INTERFACE IMPORTED)
+endif()
+EOF
+
+cat >"${prefix_dir}/lib/cmake/gRPC/gRPCConfig.cmake" <<'EOF'
+set(gRPC_FOUND TRUE)
+if(NOT TARGET gRPC::grpc++)
+  add_library(gRPC::grpc++ INTERFACE IMPORTED)
+endif()
+if(NOT TARGET gRPC::grpc++_reflection)
+  add_library(gRPC::grpc++_reflection INTERFACE IMPORTED)
+endif()
+EOF
+
+cat >"${tools_dir}/protoc" <<'EOF'
+#!/usr/bin/env sh
+exit 0
+EOF
+cat >"${tools_dir}/grpc_cpp_plugin" <<'EOF'
+#!/usr/bin/env sh
+exit 0
+EOF
+chmod +x "${tools_dir}/protoc" "${tools_dir}/grpc_cpp_plugin"
+
+assert_cache_bool() {
+  local cache_file="$1"
+  local name="$2"
+  local expected="$3"
+  grep -q "^${name}:BOOL=${expected}$" "${cache_file}" || {
+    echo "expected ${name}:BOOL=${expected} in ${cache_file}" >&2
+    return 1
+  }
+}
+
+configure_case() {
+  local name="$1"
+  local cuda="$2"
+  local vulkan="$3"
+  local metal="$4"
+  local build_dir="${tmp_dir}/build-${name}"
+
+  PATH="${tools_dir}:${PATH}" cmake \
+    -S "${backend_dir}" \
+    -B "${build_dir}" \
+    -DCMAKE_PREFIX_PATH="${prefix_dir}" \
+    -DAUDIO_CPP_DIR="${fixture_dir}" \
+    -DENGINE_ENABLE_CUDA="${cuda}" \
+    -DENGINE_ENABLE_VULKAN="${vulkan}" \
+    -DENGINE_ENABLE_METAL="${metal}" \
+    >/dev/null
+
+  assert_cache_bool "${build_dir}/CMakeCache.txt" ENGINE_ENABLE_CUDA "${cuda}"
+  assert_cache_bool "${build_dir}/CMakeCache.txt" ENGINE_ENABLE_VULKAN "${vulkan}"
+  assert_cache_bool "${build_dir}/CMakeCache.txt" ENGINE_ENABLE_METAL "${metal}"
+
+  grep -q 'engine_runtime' \
+    "${build_dir}/CMakeFiles/audio-cpp-grpc-server.dir/link.txt" || {
+    echo "audio-cpp-grpc-server does not link engine_runtime" >&2
+    return 1
+  }
+}
+
+configure_case cpu OFF OFF OFF
+configure_case cuda ON OFF OFF
+configure_case vulkan OFF ON OFF
+configure_case metal OFF OFF ON
+
+if PATH="${tools_dir}:${PATH}" cmake \
+  -S "${backend_dir}" \
+  -B "${tmp_dir}/build-wrong-option" \
+  -DCMAKE_PREFIX_PATH="${prefix_dir}" \
+  -DAUDIO_CPP_DIR="${fixture_dir}" \
+  -DGGML_CUDA=ON \
+  >/dev/null 2>&1; then
+  echo "strict audio.cpp fixture accepted legacy GGML_CUDA option" >&2
+  exit 1
+fi
+
+make_database="${tmp_dir}/make-database"
+make -C "${backend_dir}" -pn >"${make_database}"
+audio_cpp_version="$(
+  sed -n 's/^AUDIO_CPP_VERSION = //p' "${make_database}" | head -n 1
+)"
+[[ "${audio_cpp_version}" =~ ^[0-9a-f]{40}$ ]] || {
+  echo "AUDIO_CPP_VERSION must be a pinned 40-character commit" >&2
+  exit 1
+}
+
+fetch_plan="${tmp_dir}/fetch-plan"
+make -C "${backend_dir}" -n audio.cpp >"${fetch_plan}"
+grep -q 'github.com/0xShug0/audio.cpp' "${fetch_plan}"
+grep -q "${audio_cpp_version}" "${fetch_plan}"
+
+cat >"${tools_dir}/uname" <<'EOF'
+#!/usr/bin/env sh
+if [ "$#" -eq 1 ] && [ "$1" = "-s" ]; then
+  echo Darwin
+  exit 0
+fi
+echo "build contract requires uname -s" >&2
+exit 64
+EOF
+chmod +x "${tools_dir}/uname"
+
+darwin_plan="${tmp_dir}/darwin-plan"
+PATH="${tools_dir}:${PATH}" make -C "${backend_dir}" -n \
+  AUDIO_CPP_SRC="${fixture_dir}" grpc-server >"${darwin_plan}"
+grep -q -- '-DENGINE_ENABLE_CUDA=OFF' "${darwin_plan}"
+grep -q -- '-DENGINE_ENABLE_VULKAN=OFF' "${darwin_plan}"
+grep -q -- '-DENGINE_ENABLE_METAL=ON' "${darwin_plan}"
+
+echo "audio.cpp build contract: PASS"