docs: fix channel plugin guide — require Pydantic config model

docs/CHANNEL_PLUGIN_GUIDE.md

@@ -43,15 +43,30 @@ from typing import Any
 
 from aiohttp import web
 from loguru import logger
+from pydantic import Field
 
 from nanobot.channels.base import BaseChannel
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.queue import MessageBus
+from nanobot.config.schema import Base
+
+
+class WebhookConfig(Base):
+    """Webhook channel configuration."""
+    enabled: bool = False
+    port: int = 9000
+    allow_from: list[str] = Field(default_factory=list)
 
 
 class WebhookChannel(BaseChannel):
     name = "webhook"
     display_name = "Webhook"
 
+    def __init__(self, config: Any, bus: MessageBus):
+        if isinstance(config, dict):
+            config = WebhookConfig(**config)
+        super().__init__(config, bus)
+
     @classmethod
     def default_config(cls) -> dict[str, Any]:
         return {"enabled": False, "port": 9000, "allowFrom": []}
@@ -63,7 +78,7 @@ class WebhookChannel(BaseChannel):
         If it returns, the channel is considered dead.
         """
         self._running = True
-        port = self.config.get("port", 9000)
+        port = self.config.port
 
         app = web.Application()
         app.router.add_post("/message", self._on_request)
@@ -214,7 +229,7 @@ nanobot channels login <channel_name> --force  # re-authenticate
 | Method / Property | Description |
 |-------------------|-------------|
 | `_handle_message(sender_id, chat_id, content, media?, metadata?, session_key?)` | **Call this when you receive a message.** Checks `is_allowed()`, then publishes to the bus. Automatically sets `_wants_stream` if `supports_streaming` is true. |
-| `is_allowed(sender_id)` | Checks against `config["allowFrom"]`; `"*"` allows all, `[]` denies all. |
+| `is_allowed(sender_id)` | Checks against `config.allow_from`; `"*"` allows all, `[]` denies all. |
 | `default_config()` (classmethod) | Returns default config dict for `nanobot onboard`. Override to declare your fields. |
 | `transcribe_audio(file_path)` | Transcribes audio via Groq Whisper (if configured). |
 | `supports_streaming` (property) | `True` when config has `"streaming": true` **and** subclass overrides `send_delta()`. |
@@ -284,7 +299,9 @@ class WebhookChannel(BaseChannel):
     name = "webhook"
     display_name = "Webhook"
 
-    def __init__(self, config, bus):
+    def __init__(self, config: Any, bus: MessageBus):
+        if isinstance(config, dict):
+            config = WebhookConfig(**config)
         super().__init__(config, bus)
         self._buffers: dict[str, str] = {}
 
@@ -333,12 +350,48 @@ When `streaming` is `false` (default) or omitted, only `send()` is called — no
 
 ## Config
 
-Your channel receives config as a plain `dict`. Access fields with `.get()`:
+### Why Pydantic model is required
+
+`BaseChannel.is_allowed()` and the `supports_streaming` property access config fields via `getattr()` (e.g. `getattr(self.config, "allow_from", [])`). This works for Pydantic models where `allow_from` is a real Python attribute, but **fails silently for plain `dict`** — `dict` has no `allow_from` attribute, so `getattr` always returns the default `[]`, causing all messages to be denied.
+
+Built-in channels use Pydantic config models (subclassing `Base` from `nanobot.config.schema`). Plugin channels **must do the same**.
+
+### Pattern
+
+1. Define a Pydantic model inheriting from `nanobot.config.schema.Base`:
+
+```python
+from pydantic import Field
+from nanobot.config.schema import Base
+
+class WebhookConfig(Base):
+    """Webhook channel configuration."""
+    enabled: bool = False
+    port: int = 9000
+    allow_from: list[str] = Field(default_factory=list)
+```
+
+`Base` is configured with `alias_generator=to_camel` and `populate_by_name=True`, so JSON keys like `"allowFrom"` and `"allow_from"` are both accepted.
+
+2. Convert `dict` → model in `__init__`:
+
+```python
+from typing import Any
+from nanobot.bus.queue import MessageBus
+
+class WebhookChannel(BaseChannel):
+    def __init__(self, config: Any, bus: MessageBus):
+        if isinstance(config, dict):
+            config = WebhookConfig(**config)
+        super().__init__(config, bus)
+```
+
+3. Access config as attributes (not `.get()`):
 
 ```python
 async def start(self) -> None:
-    port = self.config.get("port", 9000)
-    token = self.config.get("token", "")
+    port = self.config.port
+    token = self.config.token
 ```
 
 `allowFrom` is handled automatically by `_handle_message()` — you don't need to check it yourself.
@@ -351,6 +404,8 @@ def default_config(cls) -> dict[str, Any]:
     return {"enabled": False, "port": 9000, "allowFrom": []}
 ```
 
+> **Note:** `default_config()` still returns a plain `dict` (not a Pydantic model) because it's used to serialize into `config.json`. Use camelCase keys (`allowFrom`) to match the JSON convention.
+
 If not overridden, the base class returns `{"enabled": false}`.
 
 ## Naming Convention