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docs/user/develop/framework/index.md

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+# Plugins and lifecycle
+
+English | [中文](index.zh.md)
+
+This page describes the Cordis plugin model and lifecycle state machine.
+
+## Fiber state machine
+
+Every loaded plugin owns a **Fiber** scope with the following states:
+
+```
+PENDING → LOADING → ACTIVE
+                 ↘ FAILED
+ACTIVE → UNLOADING → DISPOSED
+```
+
+| State | Meaning |
+|------|------|
+| PENDING | Declared, but required dependencies are not ready |
+| LOADING | Dependencies are ready and `apply` is running |
+| ACTIVE | The plugin is running |
+| FAILED | `apply` threw an error |
+| UNLOADING | The plugin is unloading and disposing resources |
+| DISPOSED | The plugin is fully unloaded |
+
+## Dependency-driven loading
+
+A plugin with `inject` waits for every required service before loading:
+
+```ts ignore-check
+export const inject = ['tools', 'llm']
+
+export function apply(ctx: Context) {
+  // ctx.tools and ctx.llm are ready here.
+}
+```
+
+If a required service disappears, for example during provider replacement, the plugin unloads automatically (ACTIVE → DISPOSED) and loads again when the service returns.
+
+## Automatic cleanup
+
+Every registration made through `ctx` is undone when the plugin unloads:
+
+```ts ignore-check
+export function apply(ctx: Context) {
+  // Event listener: removed automatically on unload.
+  ctx.on('some-event', handler)
+
+  // Custom resource: the returned disposer runs on unload.
+  ctx.effect(() => {
+    const connection = createConnection()
+    return () => connection.close()
+  })
+}
+```
+
+The framework tracks and disposes all of these operations:
+- `ctx.on(event, handler)` — event listener
+- `ctx.tools.register(tool)` — tool registration
+- `ctx.llm.registerAdapter(names, adapter)` — LLM adapter registration
+- `ctx.effect(() => cleanup)` — custom resource
+
+During unload, disposer invocation starts in reverse registration order, but multiple async disposers run concurrently and have no serial completion guarantee. Put order-dependent cleanup in one disposer returned from a single `ctx.effect()` and await its steps serially there.
+
+## Nested contexts
+
+`ctx.plugin()` creates a child Fiber that inherits the parent context but has an independent lifecycle:
+
+```ts ignore-check
+export function apply(ctx: Context) {
+  // Register a child plugin.
+  ctx.plugin(childPlugin)
+
+  // The child has its own Fiber and unloads with its parent.
+}
+```
+
+## Dispose semantics
+
+To stop a plugin instance early:
+
+```ts ignore-check
+const fiber = ctx.plugin(myPlugin)
+
+// Dispose it manually later.
+fiber.dispose()
+```
+
+`dispose` guarantees:
+1. All registrations owned by the plugin are removed.
+2. Child plugins are recursively unloaded.
+3. The returned promise resolves after all asynchronous cleanup finishes.
+
+## Hot replacement (HMR)
+
+With `@cordisjs/plugin-hmr` loaded from `cordis.yml`, editing a plugin source file triggers:
+
+1. Unload the old plugin and clean up its registrations.
+2. Load the new code.
+3. Run the new `apply`.
+
+Because plugin registrations clean themselves up, hot replacement does not retain registrations from the old instance.
+
+## Example lifecycle
+
+```ts ignore-check
+export function apply(ctx: Context) {
+  console.log('plugin loading')
+
+  ctx.effect(() => {
+    console.log('effect registered')
+    return () => console.log('effect cleaned up')
+  })
+}
+```
+
+Loading prints:
+```
+plugin loading
+effect registered
+```
+
+Unloading prints:
+```
+effect cleaned up
+```
+
+## Next steps
+
+- [Services and dependencies](./service.md) — expose a capability to other plugins
+- [Event system](./events.md) — communicate between plugins