feat(gateway): route Slack events through external chat

surfsense_backend/app/gateway/registry.py

@@ -6,7 +6,7 @@ from collections.abc import Callable
 from dataclasses import dataclass
 
 from app.db import ExternalChatAccount, ExternalChatAccountMode, ExternalChatPlatform
-from app.gateway.accounts import account_token
+from app.gateway.accounts import account_token, slack_account_credentials
 from app.gateway.base.adapter import BasePlatformAdapter, ParsedInboundEvent
 from app.gateway.base.commands import BaseGatewayCommands
 from app.gateway.base.translator import BaseStreamTranslator
@@ -70,6 +70,23 @@ def _whatsapp_baileys_translator_factory(
     )
 
 
+def _slack_translator_factory(
+    adapter: BasePlatformAdapter,
+    event: ParsedInboundEvent,
+) -> BaseStreamTranslator:
+    channel_id = event.metadata.get("channel_id")
+    thread_ts = event.metadata.get("thread_ts")
+    if not channel_id or not thread_ts:
+        raise RuntimeError("missing_slack_thread_metadata")
+    from app.gateway.slack.translator import SlackStreamTranslator
+
+    return SlackStreamTranslator(
+        adapter=adapter,  # type: ignore[arg-type]
+        channel_id=channel_id,
+        thread_ts=thread_ts,
+    )
+
+
 def resolve_platform_bundle(account: ExternalChatAccount) -> PlatformBundle:
     if account.platform == ExternalChatPlatform.TELEGRAM:
         token = account_token(account)
@@ -108,4 +125,24 @@ def resolve_platform_bundle(account: ExternalChatAccount) -> PlatformBundle:
                 auto_bind_owner=True,
             )
 
+    if account.platform == ExternalChatPlatform.SLACK:
+        from app.gateway.slack.adapter import SlackAdapter
+        from app.gateway.slack.commands import SlackGatewayCommands
+
+        credentials = slack_account_credentials(account)
+        bot_token = credentials.get("bot_token")
+        if not bot_token:
+            raise RuntimeError("missing_slack_bot_token")
+        cursor_state = account.cursor_state or {}
+        return PlatformBundle(
+            adapter=SlackAdapter(
+                bot_token,
+                bot_user_id=cursor_state.get("bot_user_id"),
+            ),
+            translator_factory=_slack_translator_factory,
+            platform_label="slack",
+            commands=SlackGatewayCommands(),
+            auto_bind_owner=False,
+        )
+
     raise RuntimeError(f"unsupported_gateway_platform:{account.platform.value}:{account.mode.value}")