LedgerGuard.

Recruiter case study · 5 minute read

Building AI automation that never moves money on a guess.

LedgerGuard is a solo full-stack portfolio project by Ariel Magalso, created to demonstrate controlled, measurable AI automation for a financially sensitive workflow.
Solo build · product to deployment
Role
Solo AI automation design and engineering
Stack
FastAPI · Claude · PostgreSQL · Docker
Proof
Live pipeline · evals · audit history

01 / 010

The business problem

Accounts-payable teams repeatedly copy invoice data, verify arithmetic, reconcile purchase orders and receipts, check for duplicates and supplier-detail changes, and decide who must review each exception. Delays hold up suppliers and operations; a confident wrong answer can create a duplicate payment, misclassification, fraud exposure, or real financial loss.

02 / 010

Why implement this automation

The workflow is high-volume and repetitive, but it still contains judgment points that should remain accountable. Automating document preparation and deterministic checks can shorten review cycles, surface risky exceptions earlier, preserve a consistent audit trail, and let finance teams spend more time resolving discrepancies instead of re-keying routine data.

03 / 010

The solution

LedgerGuard uses AI where invoice layouts are variable: locating and extracting candidate fields and drafting evidence-linked explanations. Deterministic code handles money, identity, duplicate rules, tolerances, routing, permissions, and idempotency. A human reviews the prepared work, and the model never decides that an invoice is financially safe.

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Expected workflow benefits

A suitable implementation can reduce manual preparation, standardize controls across teams and locations, make exception queues easier to prioritize, improve traceability, and create a reusable integration layer around existing finance systems. These are intended workflow benefits, not measured customer outcomes from this fictional portfolio demonstration.

05 / 010

Who can benefit

LedgerGuard is most relevant to organizations processing meaningful invoice volume across multiple suppliers, locations, purchase orders, receipts, or approval routes. Potential fits include facilities and property management, construction, hospitality, multi-site retail, manufacturing, logistics, healthcare administration, and professional-services companies with lean finance teams.

06 / 010

Third-party integration architecture

The workflow can be connected through APIs, webhooks, and system-specific adapters. It can receive documents and reference data, return status and evidence, notify reviewers, and prepare draft accounting records. The safety boundary remains unchanged: integrations may prepare work, but payment authorization stays outside the AI workflow.

07 / 010

What I built

I independently designed and implemented the FastAPI application, Claude extraction pipeline, evidence alignment, PostgreSQL data model, matching and control engine, five-scenario workbench, approval queue, evaluation harness, operations dashboard, sandbox accounting adapter, and deployment.

08 / 010

How risk is controlled

Every extracted field must point to document evidence. Monetary values are recalculated with decimal-safe code. Bank-detail changes are blocked, duplicate identity survives renamed files, embedded instructions remain untrusted document text, and every proposed external write carries an idempotency key.

09 / 010

How it is evaluated

The evaluation runner sends labeled fictional invoices through the actual extraction, alignment, matching, and decision pipeline. Held-out and development splits are reported separately, failures remain visible, and critical false clearances are measured independently from field-level extraction errors.

010 / 010

Current limitations

This is a portfolio demonstration, not a customer deployment. All entities and financial data are fictional. The public workflow intentionally stops before executing an accounting write or payment, and the evaluation set is still small compared with a production document population.

Industry fit

A reusable control pattern for invoice-heavy operations.

These examples describe organizations that could benefit from this architecture. They are illustrative applications, not current LedgerGuard customers.

Facilities & property management

Recurring maintenance, security, cleaning, and repair invoices routed across properties and cost centers.

Construction

Subcontractor and materials invoices reconciled with project purchase orders, receipts, and tolerances.

Hospitality & multi-site retail

Distributed invoice intake standardized across locations while local managers retain approval authority.

Manufacturing & logistics

High-volume supplier charges checked against orders, deliveries, and approved commercial terms.

Healthcare administration

Non-clinical supplier invoices prepared for controlled review with evidence and audit history.

Professional services

Growing organizations reduce repetitive AP preparation without removing human financial oversight.

Integration-ready design

Connect the controls to the systems already in use.

LedgerGuard can exchange documents, reference data, workflow state, and draft records through APIs, webhooks, and adapters. The current portfolio build includes a sandbox accounting adapter only; the named external platforms below are integration examples, not deployed connectors.

Accounting & ERP

QuickBooks, Xero, NetSuite, Sage, or SAP

Prepare draft bills, synchronize approved reference data, and return processing status through a controlled adapter.

Procurement

Coupa, SAP Ariba, or internal purchasing systems

Read purchase orders, receipts, tolerance policies, supplier records, and approval ownership.

Document intake

Email, Google Drive, SharePoint, S3, or secure upload

Receive invoices and supporting documents through APIs, webhooks, monitored inboxes, or storage events.

Collaboration & approvals

Slack, Microsoft Teams, email, or internal workflow tools

Notify the correct reviewer, link to evidence, and return human decisions without granting the model authority.

Master and identity data

Supplier master, PO, receipt, identity, and access-control systems

Compare extracted claims with authoritative records and enforce organization-specific permissions.

Safety boundary

Connected systems may supply evidence and receive prepared draft records. A named human remains responsible for approval, and no integration grants the AI permission to execute payment.

Inspect the integration architecture →

Inspect the system, not just the summary.

Run five controlled scenarios and inspect every field, rule, and decision.

Open the workbench →

Built by Ariel

Ariel Magalso
AI Engineer
Philippines · Remote

The case study connects design decisions to working evidence.

Continue into the live workbench, inspect the source and evaluations, or contact Ariel about AI automation and workflow-engineering opportunities.

Open to opportunities

Need AI automation that can explain itself?

I build measurable AI-assisted workflows with deterministic safeguards, visible evaluation, and human review where the risk demands it.

Contact Ariel