feat: Add conversion between jeff and Qiskit

.github/change-filters.yml

@@ -21,6 +21,7 @@ python: &python
   - *schema-def
   - ".github/workflows/ci-py.yml"
   - "impl/py/**"
+  - "tools/**"
   - "pyproject.toml"
   - "uv.lock"
   - "examples/**/*.py"

.gitignore

@@ -44,3 +44,6 @@ venv/
 
 # MacOS
 *.DS_Store
+
+# CMake build directory
+build/

tools/qiskit_convert/CMakeLists.txt

@@ -0,0 +1,66 @@
+cmake_minimum_required(VERSION 3.20)
+project(jeff-qiskit-convert LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+find_package(CapnProto REQUIRED)
+
+# Use pre-generated Cap'n Proto bindings from the shared implementation
+set(CAPNP_SHARED_DIR ${CMAKE_CURRENT_SOURCE_DIR}/../../impl/cpp/src/capnp)
+
+# Find Python (needed for Qiskit's C API path discovery)
+find_package(Python3 COMPONENTS Interpreter Development QUIET)
+
+# Locate Qiskit C API
+if(Python3_FOUND)
+    execute_process(
+        COMMAND ${Python3_EXECUTABLE} -c
+            "import importlib, os; m=importlib.import_module('qiskit._accelerate'); print(os.path.dirname(m.__file__))"
+        OUTPUT_VARIABLE QISKIT_API_DIR
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+        ERROR_QUIET
+    )
+endif()
+
+if(NOT QISKIT_API_DIR)
+    set(QISKIT_API_DIR "$ENV{QISKIT_ROOT}" CACHE PATH "Qiskit C API directory")
+endif()
+
+# Qiskit C API header (in capi/include/ relative to the Qiskit package)
+find_path(QISKIT_INCLUDE_DIR qiskit.h
+    PATHS ${QISKIT_API_DIR}/capi/include
+    ${QISKIT_API_DIR}/include
+    /usr/local/include/qiskit
+)
+
+# Qiskit C API shared library
+find_library(QISKIT_LIBRARY
+    NAMES _accelerate.abi3 _accelerate
+    PATHS ${QISKIT_API_DIR}
+)
+
+add_executable(jeff-qiskit-convert
+    main.cpp
+    ${CAPNP_SHARED_DIR}/jeff.capnp.c++
+)
+
+target_include_directories(jeff-qiskit-convert PRIVATE
+    ${CAPNP_SHARED_DIR}
+    ${QISKIT_INCLUDE_DIR}
+)
+
+target_link_libraries(jeff-qiskit-convert PRIVATE
+    CapnProto::capnp
+)
+
+if(QISKIT_LIBRARY AND Python3_FOUND)
+    target_link_libraries(jeff-qiskit-convert PRIVATE
+        ${QISKIT_LIBRARY}
+        Python3::Python
+    )
+    target_compile_definitions(jeff-qiskit-convert PRIVATE HAVE_QISKIT=1)
+    message(STATUS "Qiskit C API: ${QISKIT_INCLUDE_DIR}")
+else()
+    message(STATUS "Qiskit C API not found — building without Qiskit support (set QISKIT_ROOT if needed)")
+endif()