# Compatibility & deprecation

Until TaskChampion reaches [v1.0.0](https://github.com/taskchampion/taskchampion/milestone/7), nothing is set in stone. That being said, we aim for the following:

1. Major versions represent significant change and may be incompatible with previous major release.
2. Minor versions are always backwards compatible and might add some new functionality.
3. Patch versions should not introduce any new functionality and do what name implies — fix bugs.

As there are no major releases yet, we do not support any older versions. Users are encouraged to use the latest release.

## ABI policy

1. We target stable `rustc`.
2. TaskChampion will never upgrade any storage to a non-compatible version without explicit user's request.

## API policy

1. Deprecated features return a warning at least 1 minor version prior to being removed.

    Example:

    > If support of `--bar` is to be dropped in v2.0.0, we shall announce it in v1.9.0 at latest.

2. We aim to issue a notice of newly added functionality when appropriate.

    Example:

    > "NOTICE: Since v1.1.0 you can use `--foo` in conjunction with `--bar`. Foobar!"

3. TaskChampion always uses UTF-8.

## Command-line interface

Considered to be part of the API policy.

## CLI exit codes

- `0` - No errors, normal exit.
- `1` - Generic error.
- `2` - Never used to avoid conflicts with Bash.
- `3` - Command-line Syntax Error.

# Security

See [SECURITY.md](./SECURITY.md).