bext-plugin-api 0.2.0

# bext-plugin-api

**Public ABI for bext plugin authors.** This is the single crate you need to
depend on if you want to write a plugin for [bext](https://github.com/bext-stack/bext).

```toml
[dependencies]
bext-plugin-api = "0.2"
```

## What this crate is

`bext-plugin-api` defines the trait hierarchy and shared types that every
bext plugin implements. It has near-zero dependencies (just `serde`) so that
plugin authors can pull it into any Rust project without dragging in the
rest of the bext runtime.

The crate is the **stable contract** between the bext core engine and
third-party extensions. The rest of the bext codebase will break you on a
major version bump; this crate will not.

## Plugin kinds

The crate exposes trait definitions for the following plugin kinds. Each
plugin kind has its own module and its own lifecycle hooks.

| Module | Trait | Purpose |
| --- | --- | --- |
| `auth` | `AuthPlugin` | JWT, cookie, or custom authentication |
| `session` | `SessionStore` | Session persistence (cookie, redis, custom) |
| `mailer` | `Mailer` | Transactional email sending (SMTP, SES, etc.) |
| `scheduled` | `ScheduledTask` | Cron-like scheduled background jobs |
| `tracer` | `Tracer` | Structured tracing (stdout, OTLP, custom) |
| (core) | `Plugin` | Generic request/response middleware |

## Example

```rust
use bext_plugin_api::{Plugin, Request, Response};

pub struct HelloPlugin;

impl Plugin for HelloPlugin {
    fn on_request(&self, req: &Request) -> Option<Response> {
        if req.path() == "/hello" {
            Some(Response::text(200, "Hello from a bext plugin"))
        } else {
            None
        }
    }
}
```

Plugins are loaded by the bext runtime through one of the host crates:

- [`bext-plugin-wasm`](https://crates.io/crates/bext-plugin-wasm) — WASM sandbox
- [`bext-plugin-quickjs`](https://crates.io/crates/bext-plugin-quickjs) — JavaScript sandbox
- [`bext-plugin-nsjail`](https://crates.io/crates/bext-plugin-nsjail) — process isolation

## Reference implementations

The `bext-impls` sub-workspace ships reference plugins you can use as
starting points — JWT auth, cookie/Redis sessions, SMTP/SES mailers, stdout/OTLP
tracers, and a cron scheduler. Each is a complete working plugin against
this ABI, under ~500 lines of Rust.

## License

MIT. This crate must stay MIT so plugin authors can link it freely into
projects of any license.

## Stability

Pre-1.0, the ABI is evolving. Minor version bumps (0.2 → 0.3) may include
breaking changes to trait signatures. Patch bumps (0.2.0 → 0.2.1) are
additive only. Once the crate reaches 1.0 it will follow strict semver for
the public ABI.