hg_cpp

A clean-slate, C++-first reimplementation of the hgraph functional-reactive time-series runtime. The C++ runtime is the source of truth; Python is a planned wiring/compat bridge, never the foundation. Graphs are authored, wired, tested, and executed entirely in C++ today — in simulation or real-time mode, including push sources, higher-order operators (map_ / switch_ / reduce / mesh_), services, and error handling.

Build & test

cmake -S . -B build                 # configure (fmt + Catch2 fetched if absent)
cmake --build build -j              # build hgraph_core + tests
ctest --test-dir build --output-on-failure

Requires a C++23 compiler and CMake ≥ 3.25. Python/nanobind are not needed for the default build (bindings are opt-in via -DHGRAPH_BUILD_PYTHON_BINDINGS=ON).

Documentation

Sphinx docs live under docs/source (pip install -r docs/requirements.txt, then sphinx-build -W -b html docs/source docs/_build/html):

• User guide — start at docs/source/user_guide/quick_start.rst, then the authoring/testing guides for nodes, graphs, and the eval_node harness.
• Developer guide — the authoritative design records (docs/source/developer_guide/): architecture, data structures, wiring, nested graphs, mesh, services, error handling, operators, roadmap.

Contributing / AI sessions

• AGENTS.md — canonical project direction: goals, build philosophy, source layout, dependency policy, git hygiene.
• CLAUDE.md — the operational working guide: the enforced design-first workflow (docs change in the same commit as code), guardrails, architecture map, and current state.
• Reference trees under ext/ are read-only: ext/main is the canonical Python hgraph reference; ext/2603 / ext/2604 are earlier C++ snapshots.