Roadmap

Done — the engine

Resolver framework — lazy, per-run-cached facts; dotted-path Value, ToHash, Names; Add / AddFunc / AddValue custom facts.
Core fact groups — os (incl. os.macosx), kernel*, networking (interfaces + bindings + primary), processors, memory (+swap), mountpoints, filesystems, disks, virtual / is_virtual, system_uptime, timezone, identity, path, facterversion, plus the flat legacy aliases.
Facter 4 parity facts — dmi (bios / board / chassis / product, with the bios_* / productname / serialnumber / uuid aliases), ssh host keys + SSHFP fingerprints, selinux, load_averages, cloud / ec2_metadata, ruby, fips_enabled, aio_agent_version, augeasversion, env_windows_installdir.
External facts — facts.d: JSON / YAML / txt + executable facts.
CLI — facter full dump or single dotted-path query, JSON / YAML.
Quality — 100% coverage including error branches, gofmt + go vet clean, CI green on Linux, macOS and Windows across the six 64-bit Go targets (amd64, arm64, riscv64, loong64, ppc64le, s390x).

go-ruby-facter — the Ruby binding: maps Facter.value / Facter[] / Facter.add / Facter.to_hash and the custom-fact DSL onto this engine, so Puppet manifests and Ruby code under rbgo resolve facts. Owned by a separate effort; this engine’s stable API is its contract.
Deeper per-OS facts — Windows memory / uptime without cgo, richer cloud-provider metadata beyond the base cloud / ec2_metadata facts, and structured partitions.
External-fact caching (TTL) to mirror Facter’s cached custom facts.