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

# When a source is missing

> What happens to your figures when a connected system stops answering — why billing is the one that stops everything, and why nothing is estimated to fill the gap.

<Note>
  The behaviour below is designed and fixed. The typed refusals it describes are served over connections that are not built yet, so today they govern what you see in Beacon rather than what another system receives.
</Note>

Each rule states what Beacon does, the mechanism behind it, and how to check it.

## Without billing, nothing runs

Billing is the only required source. Without it there is no revenue record to compute from, so no figure is produced at all — not a reduced one, not a provisional one.

**Mechanism:** a module activates only once the sources it depends on are connected and returning data. **Verify:** connect billing last. Every surface stays empty until it lands, and none of them shows a partial figure in the meantime.

## Every other source degrades in a declared way

When a non-billing source is missing, the module does not switch off. It keeps publishing what it can still compute and stops publishing what it cannot — and which is which is decided in advance, not worked out at the time.

**Mechanism:** each module declares, source by source, what stays available and what becomes unavailable without it. **Verify:** disconnect one optional source. The figures that depend on it change together; nothing else moves.

## A figure computed without a source says so

A figure produced on a reduced basis is labelled as such, and the label travels with it — on the screen, in an export, and on any connection reading it.

**Mechanism:** the reduced state is attached to the value, not to the page it appears on. **Verify:** read the same figure two ways. The label is on both, or neither is the same figure.

## A coarser basis is labelled; a missing one is named

These are different outcomes and Beacon does not blur them. Where a rougher basis exists, the figure is published on it and labelled. Where none exists, the figure is **withheld and named as unavailable** — never smoothed, never carried forward from last period.

**Mechanism:** the two dispositions are declared per figure, in advance. **Verify:** every reduced figure names its basis; every withheld one names what is missing.

## Nothing is estimated to fill the gap

An absent source makes part of a calculation inactive. It does not make it approximate. Beacon does not infer, interpolate or default a value it has not been given.

**Mechanism:** there is no path that produces a figure from inputs Beacon does not hold. **Verify:** the same question returns the same answer, or the same named refusal, to every reader at every hour.

## You are told which source, and what would restore it

A figure that cannot be served comes back as a stated reason rather than an empty cell — including which source is missing and what would bring the figure back.

**Mechanism:** unavailability is a typed response, never a null. The reasons are listed under [Unavailable figures are named, not estimated](/boundaries). **Verify:** the response names a cause you can act on.

***

[Troubleshooting](/troubleshooting) covers what to do about each of these in your own systems. [Boundaries](/boundaries) covers the limits Beacon holds to everywhere else.