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

# Interface: Sources

> Read the coverage and freshness of an installed source.

[server](/api/modules/server).Sources

Read the coverage and freshness of an installed source.

A source is named by the opaque handle the engine stamps on every row it
publishes (`source_id`), and coverage is disclosed under exactly the
authority those rows are: a caller a relation's read rule refuses for a
source's rows is refused here for the same reason. The read participates in
dependency tracking like any other, so a result that concluded "we cannot
establish this" is reevaluated when the source's coverage changes.

## Methods

### coverage

▸ **coverage**(`sourceId`, `options?`): `Promise`\<[`SourceCoverage`](/api/modules/server#sourcecoverage)>

Optionally require that the source publishes into this component's named
table. This check includes empty sources, whose binding cannot be inferred
from returned rows. A mismatch releases no coverage.

#### Parameters

| Name | Type | Description |
| :- | :- | :- |
| `sourceId` | `string` | - |
| `options?` | `Object` | - |
| `options.table?` | `string` | - |
| `options.barrier?` | [`SourceBarrier`](/api/modules/server#sourcebarrier) | Enforced by the same transaction that reads coverage and rows. Complete-version barriers refuse partial publication and held gaps. |

#### Returns

`Promise`\<[`SourceCoverage`](/api/modules/server#sourcecoverage)>