v0.4.0 — Conformance harness

[0.4.0] — 2026-06 — Working Draft

Added

• Conformance harness (conformance/) — the machine-runnable suite behind the
  "SIGNET Certified" mark. Implements CDM §13 and the certification neutrality
  rules CN-1…CN-4.
  • levels.md — Core vs Full levels; requirements C-DOC, C-EVT, C-PROV (Core)
    and F-MAP, F-SEM (Full); CN neutrality rules.
  • certification.md — the identical-for-all certification process.
  • runner/run-conformance.js — runs the suite against any implementation via a
    small adapter, emits a machine-readable report, computes the level achieved.
  • adapter/reference-adapter.js — a complete conformant implementation (reaches
    Full); adapter/broken-adapter.js — deliberately non-conformant, failed
    by the harness at C-EVT and F-MAP, proving the suite discriminates.
  • Positive + negative document fixtures (invalid documents that MUST be rejected).
  • report-schema.json — schema every conformance report conforms to (CN-4).
• CI now runs the harness on every commit: the reference implementation must reach
  Core+, and the broken implementation must be rejected.

Changed

• tools/signet-to-ubl.js refactored to export a pure toUBL(invoice) function
  (shared by the CLI, the harness, and the website); CLI output unchanged.