fix(delivery): strip HTML tags for plain-text messaging surfaces

Models occasionally produce HTML tags in their output. While these render
fine on web surfaces, they appear as literal text on WhatsApp, Signal,
SMS, IRC, and Telegram.

Add sanitizeForPlainText() utility that converts common inline HTML to
lightweight-markup equivalents and strips remaining tags. Applied in the
outbound delivery pipeline for non-HTML surfaces only.

Closes #31884
See also: #18558

src/infra/outbound/deliver.ts

@@ -33,6 +33,7 @@ import { ackDelivery, enqueueDelivery, failDelivery } from "./delivery-queue.js"
 import type { OutboundIdentity } from "./identity.js";
 import type { NormalizedOutboundPayload } from "./payloads.js";
 import { normalizeReplyPayloadsForDelivery } from "./payloads.js";
+import { isPlainTextSurface, sanitizeForPlainText } from "./sanitize-text.js";
 import type { OutboundSessionContext } from "./session-context.js";
 import type { OutboundChannel } from "./targets.js";
 
@@ -445,13 +446,23 @@ async function deliverOutboundPayloadsCore(
       text: normalizedText,
     };
   };
-  const normalizedPayloads = normalizeReplyPayloadsForDelivery(payloads).flatMap((payload) => {
-    if (channel !== "whatsapp") {
-      return [payload];
-    }
-    const normalized = normalizeWhatsAppPayload(payload);
-    return normalized ? [normalized] : [];
-  });
+  const normalizedPayloads = normalizeReplyPayloadsForDelivery(payloads)
+    .flatMap((payload) => {
+      if (channel !== "whatsapp") {
+        return [payload];
+      }
+      const normalized = normalizeWhatsAppPayload(payload);
+      return normalized ? [normalized] : [];
+    })
+    .map((payload) => {
+      // Strip HTML tags for plain-text surfaces (WhatsApp, Signal, etc.)
+      // Models occasionally produce <br>, <b>, etc. that render as literal text.
+      // See https://github.com/openclaw/openclaw/issues/31884
+      if (!isPlainTextSurface(channel) || !payload.text) {
+        return payload;
+      }
+      return { ...payload, text: sanitizeForPlainText(payload.text) };
+    });
   const hookRunner = getGlobalHookRunner();
   const sessionKeyForInternalHooks = params.mirror?.sessionKey ?? params.session?.key;
   if (