Two copies of one list

cpmdc keeps its capability list twice. src/cpmdc_features.c compiles it into the library, where cpmdc_feature_count(), cpmdc_feature_table(), and cpmdc_feature_find() serve it at run time. schema/inventory/cpmd_features.json holds the same rows with metadata for the checks. The Meson suite fails when the two copies, the schema, the headers, or the docs drift apart.

Feature IDs

Namespace	Kind	Example	Means
abi.*	CPMDC_FEATURE_ABI	abi.cpmdc_session_calculate_result	an exported C function
params.*	CPMDC_FEATURE_PARAMS	params.cutOffRy	a top-level CPMDParams field
params.inputSections.<arm>.<field>	CPMDC_FEATURE_PARAMS	params.inputSections.cpmd.maxIter	a typed field inside a section arm
catalog.section.*	CPMDC_FEATURE_SECTION	catalog.section.PIMD	a deck section OpenCPMD’s parser reads with inscan('&NAME')
catalog.cpmd.*	CPMDC_FEATURE_KEYWORD	catalog.cpmd.ODIIS	a &CPMD keyword or inline option spelling
catalog.dft.*	CPMDC_FEATURE_KEYWORD	catalog.dft.PCGC	a &DFT keyword
section.*	inventory only	section.generic	a CPMDInputSection union arm

A params.* row names a field you can write. A catalog.* row says that the renderer can emit a keyword or section, often through a text field of a typed section rather than a field of its own. stub_applicable and embed_applicable say whether the stub build and the OpenCPMD build expose the row.

Query it from C

const CPMDCFeatureEntry *e = cpmdc_feature_find("params.inputSections.cpmd.odiisVectors");
if (e != NULL && e->embed_applicable) {
  /* this library renders ODIIS with a vector count */
}
for (size_t i = 0; i < cpmdc_feature_count(); ++i) {
  const CPMDCFeatureEntry *row = &cpmdc_feature_table()[i];
  /* row->feature_id, row->kind, row->stub_applicable, row->embed_applicable */
}

The inventory file

Top-level keys of schema/inventory/cpmd_features.json:

Key	Holds
version	inventory format version
schema	the schema file it describes
opencpmd_reference	the OpenCPMD source it was probed against, as a description, never a local path
opencpmd_inscan_sections, cpmd_sections	the 25 sections OpenCPMD parses with inscan; the two lists must be equal
section_kinds	the CPMDSectionKind enum values with their section.* IDs
params_fields	the top-level CPMDParams fields
abi_symbols	every public cpmdc_* function
cpmd_keywords, dft_keywords, dft_functionals	keyword and functional catalogs
features	one object per row: feature_id, kind, name, stub_applicable, embed_applicable, role

Plain-text companions in schema/inventory/: opencpmd_sections.txt (the section allowlist), cpmd_cp_keywords.txt (base &CPMD keywords), dft_functionals.txt, and surface_map_abi.txt.

The checks

All run in the default Meson suite; the inventory suite selects most of them.

Test	Fails when
feature-inventory	the JSON inventory disagrees with schema/Potentials.capnp, the C table, the public headers, the README, or the option docs; with CPMD_ROOT set, also when the live inscan probe finds a section the inventory lacks
cpmd-base-keyword-inventory	a base &CPMD keyword in cpmd_cp_keywords.txt has no catalog.cpmd.* row
cpmd-params-field-inventory	a top-level CPMDParams field has no params.* row, or the inventory or the C table has a duplicate
cpmd-public-abi-inventory	a public cpmdc_* function is missing from abi_symbols, the table, or its implementation in src/cpmdc.c, src/cpmdc_stub.c, or src/cpmdc_features.c
stub-abi-symbol-coverage	the stub test does not assert every abi_symbols row
shared-dlopen-symbol-coverage	the dlopen test does not load every abi_symbols entry from libcpmdc.so
cpmd-schema-render-coverage	a typed CPMDCpmdSection field has no render mapping
cpmd-option-token-coverage	an inline option token in a fixture has no render coverage
cpmd-typed-render-field-coverage	a typed cpmd, system, dft, or atoms field is absent from the render fixtures and assertions
cpmd-long-tail-section-coverage	a CPMDDirectiveSection arm is missing from the long-tail fixture, the render assertions, or the option reference
cpmd-escape-hatch-coverage	inputBlocks, generic, set, or raw lose schema, fixture, render, or docs coverage

Run them together:

meson test -C build --suite inventory --print-errorlogs

To include the live probe, point CPMD_ROOT at an OpenCPMD source tree:

CPMD_ROOT=/path/to/opencpmd meson test -C build feature-inventory -v

A passing live probe prints probed /path/to/opencpmd: 25 inscan sections. Without CPMD_ROOT the test prints a warning and skips that part.

Add a row

Adding a typed keyword touches the schema, the renderer, the C table, the inventory file, and the option docs in one change; the contributing guide lists the files and the focused test command.