Re-write net docs

docs/net/adapter.md

@@ -0,0 +1,70 @@
+# Adapter
+
+Adapters provide a unified interface for communicating with relays. Adapters aren't meant to be used directly, but as an injection point for custom logic.
+
+## Core Classes
+
+### `AbstractAdapter`
+
+Base class for all adapters. Handles events and cleanup.
+
+- `send(message)` - Send message to relay
+- `cleanup()` - Clean up resources
+- Emits `AdapterEvent.Receive` when messages arrive
+
+### Built-in Adapters
+
+- `SocketAdapter(socket)` - WebSocket relay connections
+- `LocalAdapter(relay)` - Local in-memory relays
+- `MockAdapter(url, sendHandler)` - Testing with manual control
+
+### Factory
+
+`getAdapter(url, context?)` creates the appropriate adapter:
+
+```typescript
+const adapter = getAdapter('wss://relay.example.com')
+adapter.on(AdapterEvent.Receive, (message, url) => {
+  console.log('Received:', message)
+})
+adapter.send(['REQ', 'sub1', {}])
+adapter.cleanup()
+```
+
+## Custom Adapter Example
+
+Custom adapters can be created against any target:
+
+```typescript
+class IPFSAdapter extends AbstractAdapter {
+  constructor(private url string) {
+    super()
+
+    // Set up an IPFS connection here
+  }
+
+  get urls() { return [this.url] }
+  get sockets() { return [] }
+
+  send(message: ClientMessage) {
+    // Handle messages as if the ipfs backend was a relay
+  }
+}
+```
+
+Custom adapters can also be provided to several net utilities, including `publish` and `request`:
+
+```typescript
+request({
+  relays: ['ipfs://QmTy8w65yBXgyfG2ZBg5TrfB2hPjrDQH3RCQFJGkARStJb'],
+  filters: [{kinds: [1]}],
+  context: {
+    getAdapter: (url: string) => {
+      // getAdapter optionally returns an adapter. If none is returned, the stock adapters will be used.
+      if (url.startsWith('ipfs://')) {
+        return new IPFSAdapter(url)
+      }
+    },
+  },
+})
+```