# Policy examples

These examples illustrate modelling choices. They are not installed workflows or
claims about a particular tenant. The integrating product supplies its business
meaning and data; Amon Sul executes the declared operations and interprets their
exit conditions through policy.

## Required-data review

An invoice application supplies an entity and required fields. A sequence fetches
or receives the data, then a CHECK reports `required_data_present` or
`required_data_missing`. Both can be completed CHECK executions.

One policy routes missing data to `needs_information`; another preserves the
current status and records a warning. The policy owns route/severity. The action
does not hard-code invoice approval, and Amon Sul does not infer which metadata
keys should be required.

## Calculation followed by an external update

A CODE action normalises caller-supplied values. A CALL or ODATA action sends the
result to an external application. The action contract names outputs, and sequence
mapping passes them into the next step. The policy interprets declared outcomes
and defines the next status.

Configure the connection code separately in each lane. A shared action targets
test credentials in the test lane and production credentials in production.
Where the external update has a side effect, the destination needs its own
idempotency or reconciliation contract for uncertain delivery.

## Several tracks for one entity

A composite policy can maintain different tracks, such as review and settlement,
with cross-track dependencies. The entity response identifies each track and
its concrete offered sequences. A prerequisite can make a sequence unavailable
with a blocked reason without implying that the worker is broken.

Composite UI is feature gated. Use contract-backed examples and the public
catalog rather than assuming every tenant has this configuration enabled.

## Build an executable example

Follow [getting started](https://docs.amonsul.io/guides/getting-started/) and [Run a policy execution](https://docs.amonsul.io/guides/policy-execution/).
Use [Matrix JSON guide](https://docs.amonsul.io/developers/workflow-json/) for exact importable
syntax, contracts, and preserved outcomes. Review each example's connection and
business meaning before binding it to real data.