feat(bot): add MAX notifications adapter and operator handoff

Refs #83

app/channels/max_client.py

@@ -0,0 +1,101 @@
+"""Small MAX Bot API client. Secrets stay in headers; failures never expose response bodies."""
+
+import logging
+import ssl
+
+import httpx
+
+from app.config import Settings
+
+API_URL = "https://platform-api2.max.ru"
+UPDATE_TYPES = ["bot_started", "message_created", "bot_stopped", "dialog_removed"]
+
+
+class _HideRecipient(logging.Filter):
+    def filter(self, record: logging.LogRecord) -> bool:
+        # httpx INFO normally logs query strings, which include a MAX user_id.
+        return "platform-api2.max.ru" not in record.getMessage()
+
+
+logging.getLogger("httpx").addFilter(_HideRecipient())
+
+
+class MaxApiError(Exception):
+    def __init__(self, code: str, *, retryable: bool = False, retry_after: float = 0):
+        self.code, self.retryable, self.retry_after = code, retryable, retry_after
+        super().__init__(code)
+
+
+class MaxClient:
+    def __init__(self, settings: Settings, *, transport: httpx.AsyncBaseTransport | None = None):
+        context = ssl.create_default_context()
+        if settings.max_ca_bundle:
+            context.load_verify_locations(cafile=str(settings.max_ca_bundle))
+        self.http = httpx.AsyncClient(
+            base_url=API_URL,
+            headers={"Authorization": settings.max_bot_token.get_secret_value()},
+            timeout=httpx.Timeout(5),
+            verify=context,
+            follow_redirects=False,
+            transport=transport,
+        )
+
+    async def close(self) -> None:
+        await self.http.aclose()
+
+    async def request(self, method: str, path: str, **kwargs) -> dict:
+        try:
+            response = await self.http.request(method, path, **kwargs)
+        except httpx.RequestError:
+            raise MaxApiError("transport", retryable=True) from None
+        if not response.is_success:
+            try:
+                delay = min(3600, max(0, float(response.headers.get("Retry-After", "0"))))
+            except ValueError:
+                delay = 0
+            raise MaxApiError(
+                f"http_{response.status_code}",
+                retryable=response.status_code in (408, 429) or response.status_code >= 500,
+                retry_after=delay,
+            )
+        try:
+            data = response.json()
+        except ValueError:
+            raise MaxApiError("invalid_response", retryable=True) from None
+        if not isinstance(data, dict):
+            raise MaxApiError("invalid_response", retryable=True)
+        if data.get("success") is False:
+            raise MaxApiError("rejected")
+        return data
+
+    async def send(self, user_id: int, text: str, *, site_url: str, button: str) -> None:
+        data = await self.request(
+            "POST",
+            "/messages",
+            params={"user_id": user_id, "disable_link_preview": "true"},
+            json={
+                "text": text,
+                "notify": True,
+                "attachments": [
+                    {
+                        "type": "inline_keyboard",
+                        "payload": {"buttons": [[{"type": "link", "text": button, "url": site_url}]]},
+                    }
+                ],
+            },
+        )
+        if not isinstance(data.get("message"), dict):
+            raise MaxApiError("missing_message", retryable=True)
+
+    async def subscribe(self, settings: Settings) -> None:
+        data = await self.request(
+            "POST",
+            "/subscriptions",
+            json={
+                "url": settings.max_webhook_url,
+                "update_types": UPDATE_TYPES,
+                "secret": settings.max_webhook_secret.get_secret_value(),
+            },
+        )
+        if data.get("success") is not True:
+            raise MaxApiError("subscription_not_confirmed")