> ## Documentation Index
> Fetch the complete documentation index at: https://zenorent.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Core Concepts

> The building blocks you'll see across every module: modules, documents, contacts, lifecycle, and the audit trail.

The vocabulary Zeno uses across modules. If something in a module looks unfamiliar, it maps to one of these.

## Modules

Zeno is organized into modules. **Books** is always on for every organization. The operational modules — Rental, Development, Contractor, Practice, Glass, Expenses, and Budgeting — can be turned on or off in [Admin](https://zenorent.com/docs/admin.md). Most data lives inside a module, but a few things are shared across the workspace:

* **Inbox** — any document, any module (can be turned off in Admin)
* **Contacts** — every person or company, regardless of role
* **Document Center**, **Reports**, **Audit Log**, **Emails** — always on
* **Tasks & Notes**, **Inbox**, and **Chat** — shared features that can be turned on or off

Switch modules from the mode pills in the top bar. If you want a quick map of what belongs where, start with [Modules](https://zenorent.com/docs/modules.md).

## Receivable and Payable

Every module that handles money uses the same two labels:

* **Receivable** — money owed **to** you. Rental tenant invoices, development unit-sale invoices, contractor job invoices, practice client invoices, glass job balances.
* **Payable** — money **you** owe. Bills from vendors. Each module tracks its own bills so costs stay attached to the right property, project, job, or workflow.

A **bill** is always something a vendor sent you. An **invoice** is always something you sent a customer (or tenant, or buyer).

## Document lifecycle

Invoices, bills, and credit memos all move through the same states:

* **Draft** — editable, not yet counted in balances.
* **Issued** (or **Open**) — posted to the ledger. Editing is restricted.
* **Partial** — some payments or credits applied, balance remains.
* **Paid** — balance is zero.
* **Void** — cancelled. Kept for the audit trail; does not affect balances.

One action changes the state:

* **Post** — takes a draft live. Happens automatically on save in most places.

A posted document stays directly editable until a payment is applied against it. After that, it's read-only — remove the payment applications first if you need to change it, then re-apply.

## Contacts

Everyone Zeno interacts with is a contact: tenants, buyers, customers, vendors, contractors, employees. The **Contacts** page lists them all — filter by role, module, or linked property or project. Each role has its own color badge.

A contact can hold more than one role — a vendor on one project can be a customer on another — and Zeno keeps the relationships separate.

## Inbox

The [Inbox](https://zenorent.com/docs/workflow/inbox.md) is the single intake point. Upload anything — rent checks, leases, vendor bills, receipts, contracts — and Zeno's AI classifies the document, extracts the data, and routes it to the right module for your review. Nothing is filed until you confirm.

## Document Center

The [Document Center](https://zenorent.com/docs/workflow/document-center.md) is the global library of filed documents across every module. Use it when you need to find a file but do not want to guess which module page it belongs to.

## Books and the general ledger

Every financial action — invoice posted, payment received, bill paid, transaction approved from a bank feed — produces a **journal entry** in Books. You see the resulting transactions in **Registers** (per account) and **Review** (pending bank-feed items). The **Chart of Accounts** is the list of GL accounts the entries post to.

You don't need to touch Books to use the app. It runs in the background as you work in the other modules, which is what makes Zeno behave like one connected workspace instead of separate point solutions.

## Live sync

Zeno is real-time. When you or a teammate changes something, the update appears across open pages and other browser tabs without a refresh. A spinning indicator in the Inbox means a document is still being processed — the page will update itself when it's done.

## Audit trail

Every create, edit, delete, post, void, and amend is logged with the user, timestamp, and IP. You can see a document's history on its detail page, or browse everything in **More → Audit Log**. Actions taken by the AI Bookkeeper are logged with the human user who approved them, flagged as "via bookkeeper."


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