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The 5 Guards

QWED-Finance uses Neurosymbolic AI - combining neural (LLM) outputs with symbolic (math/logic) verification.

1. Compliance Guard (Z3)​

Purpose: Verify KYC/AML regulatory decisions using formal boolean logic.

from qwed_finance import ComplianceGuard

guard = ComplianceGuard()

# AML Threshold Check (BSA/FinCEN)
result = guard.verify_aml_flag(
    amount=15000,
    country_code="US",
    llm_flagged=True
)
# result.compliant = True ✅
# result.proof = "amount >= 10000 → CTR required"

Methods​

MethodDescription
verify_aml_flag()Check CTR threshold ($10,000)
verify_kyc_complete()Validate KYC document requirements
verify_transaction_limit()Enforce daily limits
verify_sanctions_check()OFAC sanctions screening

How Z3 Works​

# Z3 proves: IF amount >= 10000 THEN flag_required
from z3 import *
amount = Real('amount')
flag = Bool('flag')
solver = Solver()
solver.add(Implies(amount >= 10000, flag == True))

2. Calendar Guard (SymPy)​

Purpose: Deterministic day count conventions for interest calculations.

from qwed_finance import CalendarGuard, DayCountConvention
from datetime import date

guard = CalendarGuard()

# Verify 30/360 day count
result = guard.verify_day_count(
    start_date=date(2026, 1, 1),
    end_date=date(2026, 7, 1),
    llm_days=180,
    convention=DayCountConvention.THIRTY_360
)
# result.verified = True ✅

Supported Conventions​

ConventionUse Case
ACTUAL_ACTUALUS Treasury bonds
ACTUAL_360T-Bills, Commercial paper
ACTUAL_365UK Gilts
THIRTY_360Corporate bonds
THIRTY_E_360Eurobonds

3. Derivatives Guard (Black-Scholes)​

Purpose: Options pricing and margin verification using pure calculus.

from qwed_finance import DerivativesGuard, OptionType

guard = DerivativesGuard()

# Verify Black-Scholes call price
result = guard.verify_black_scholes(
    spot_price=100,
    strike_price=105,
    time_to_expiry=0.25,
    risk_free_rate=0.05,
    volatility=0.20,
    option_type=OptionType.CALL,
    llm_price="$3.50"
)
# result.greeks = {"delta": 0.4502, "gamma": 0.0389, ...}

Methods​

MethodDescription
verify_black_scholes()Options pricing with Greeks
verify_delta()Delta calculation
verify_margin_call()Margin call decision
verify_put_call_parity()Arbitrage detection

4. Message Guard (XML Schema)​

Purpose: Validate ISO 20022 and SWIFT messages before transmission.

from qwed_finance import MessageGuard, MessageType

guard = MessageGuard()

# Verify pacs.008 payment message
result = guard.verify_iso20022_xml(
    xml_string=pacs008_xml,
    msg_type=MessageType.PACS_008
)
# result.valid = True/False
# result.errors = ["Missing required element: GrpHdr"]

Supported Formats​

FormatDescription
PACS_008Customer Credit Transfer
CAMT_053Bank Statement
PAIN_001Payment Initiation
MT103SWIFT Single Transfer
MT202SWIFT Bank Transfer

SWIFT MT Validation​

# Validate MT103 fields
result = guard.verify_swift_mt(
    mt_string=mt103_message,
    mt_type=SwiftMtType.MT103
)
# Checks Field 20, 32A, 50K, 59, etc.

5. ISOGuard (JSON Schema)​

Purpose: Enforce ISO 20022 compliance for JSON-based Agentic Banking.

from qwed_finance import ISOGuard

guard = ISOGuard()

# Verify pacs.008 (JSON format)
result = guard.verify_payment_message(
    message={
        "MsgId": "1234AB",
        "CreDtTm": "2026-01-28T10:00:00",
        "NbOfTxs": 1,
        "TtlIntrBkSttlmAmt": {"amount": 100.50, "currency": "USD"}
    },
    msg_type="pacs.008"
)
# result.verified = True ✅

Why JSON vs XML?​

While MessageGuard handles traditional XML SWIFT messages, ISOGuard enables Modern Banking Agents to speak the same standard using lightweight JSON.

6. Query Guard (SQLGlot)​

Purpose: Prevent SQL injection and unauthorized data access.

from qwed_finance import QueryGuard

guard = QueryGuard(allowed_tables={"transactions", "accounts"})

# Check read-only safety
result = guard.verify_readonly_safety(
    "DELETE FROM users WHERE id=1"
)
# result.safe = False ❌
# result.violations = ["Mutation detected: DELETE statement"]

Methods​

MethodDescription
verify_readonly_safety()Block INSERT/UPDATE/DELETE/DROP
verify_table_access()Whitelist allowed tables
verify_column_access()Block PII columns
verify_no_injection()Detect injection patterns

Why AST, Not Regex?​

-- Regex might miss this:
SELECT * FROM (DELETE FROM users RETURNING *) AS x

-- SQLGlot AST catches it by parsing the tree structure

Cross-Guard (Multi-Layer)​

Purpose: Combine multiple guards for comprehensive verification.

from qwed_finance import CrossGuard

guard = CrossGuard()

# SWIFT + Sanctions in one call
result = guard.verify_swift_with_sanctions(
    mt_string=swift_message,
    sanctions_list=["ACME Corp", "Bad Bank LLC"]
)
# Validates SWIFT format AND screens entities
PyPI Package

All guards are available via pip install qwed-finance