Changelog

All notable changes to this project will be documented in this file.

[0.2.0] - 2026-06-22

TaxDiagnosticResult — 3-layer structured diagnostic model (agent message / developer fields / proof ref) with tri-state status (VERIFIED / UNVERIFIABLE / BLOCKED). Closes #39.
to_diagnostic() on all 12 guards — every guard now converts its legacy dict return into a TaxDiagnosticResult with cryptographic proof_ref. Closes #47.
Audit trace — build_trace() + RuleRef entries for all 12 guards, covering IRS, CBDT, CBIC, FEMA, and OECD statutory references.
15 new RuleRef constants in audit.py — CG (112A, 111A, 50AA), Speculation (43(5), 73), Inter-head (71, 74), VDA (115BBH), PoEM (6(3), CBDT 6/2017), FEMA (LRS, Schedule I, 206CR), IRS (Common Law, Pub 505), SAFE conversion.
trace_proof_ref() — deterministic SHA-256 hash over audit trace, binds VERIFIED verdicts to specific evidence.
TaxAdvisoryCheck — non-proof-bearing advisory metadata model with advisory_only=True invariant.

#16 — Fail-closed on unknown/unmodeled tax rules across all guards. Unknown services, states, asset types, and source strings now return verified=False instead of silently passing.
#17, #18 — Classification guard fail-closed on ambiguous facts + claim comparison. Mixed employee/contractor indicators no longer default to contractor.
#19, #40 — Middleware success label narrowed + ReciprocityGuard Z3 removed. ARITHMETIC_VERIFIED is a pre-conformance status, not a verification pass. Z3 solver replaced with deterministic lookup.
#20, #21, #22 — Input strictness: exact paise comparison (no tolerance), edge-case validation (negative amounts, zero values, discount=1), extra="forbid" on all 8 Pydantic input models.
#34, #31 — README repositioned as verification layer, not tax platform. "Production Ready" claims removed, non-goals section added, comparison table promoted to top.

CryptoTaxGuard — TaxResult pydantic model now includes optional audit_trace field.
PoEMGuard — _unverifiable() helper now emits audit_trace with INPUT_VALIDATION_FAILED outcome.
TaxDiagnosticResult.__post_init__ — hardened with isinstance type checks for status, agent_message, and developer_fields.
TaxDiagnosticResult.from_dict — validates status type (str → enum) and developer_fields type before construction.
to_diagnostic() fail-closed — all 12 guards raise ValueError when verified=True but audit_trace is None.
BLOCKED vs UNVERIFIABLE — to_diagnostic() now differentiates based on audit_trace["outcome"]: insufficient evidence/unknown rule → UNVERIFIABLE, claim wrong/invalid input → BLOCKED.

270 tests (up from 83 in v0.1.0).
50 new tests for to_diagnostic() conversions covering VERIFIED, BLOCKED, UNVERIFIABLE, fail-closed, and serialization round-trip paths.
32 tests for TaxDiagnosticResult model, factory methods, TaxAdvisoryCheck, and from_dict/to_dict.