Slack: add some fixes and connect it all up

src/gateway/server-methods/send.ts

@@ -3,6 +3,7 @@ import { sendMessageDiscord } from "../../discord/index.js";
 import { shouldLogVerbose } from "../../globals.js";
 import { sendMessageIMessage } from "../../imessage/index.js";
 import { sendMessageSignal } from "../../signal/index.js";
+import { sendMessageSlack } from "../../slack/send.js";
 import { sendMessageTelegram } from "../../telegram/send.js";
 import { resolveTelegramToken } from "../../telegram/token.js";
 import { sendMessageWhatsApp } from "../../web/outbound.js";
@@ -87,6 +88,22 @@ export const sendHandlers: GatewayRequestHandlers = {
           payload,
         });
         respond(true, payload, undefined, { provider });
+      } else if (provider === "slack") {
+        const result = await sendMessageSlack(to, message, {
+          mediaUrl: request.mediaUrl,
+        });
+        const payload = {
+          runId: idem,
+          messageId: result.messageId,
+          channelId: result.channelId,
+          provider,
+        };
+        context.dedupe.set(`send:${idem}`, {
+          ts: Date.now(),
+          ok: true,
+          payload,
+        });
+        respond(true, payload, undefined, { provider });
       } else if (provider === "signal") {
         const cfg = loadConfig();
         const host = cfg.signal?.httpHost?.trim() || "127.0.0.1";