fix: suppress reasoning payload leakage in whatsapp replies

src/web/auto-reply/deliver-reply.test.ts

@@ -70,6 +70,56 @@ const replyLogger = {
 };
 
 describe("deliverWebReply", () => {
+  it("suppresses payloads flagged as reasoning", async () => {
+    const msg = makeMsg();
+
+    await deliverWebReply({
+      replyResult: { text: "Reasoning:\n_hidden_", isReasoning: true },
+      msg,
+      maxMediaBytes: 1024 * 1024,
+      textLimit: 200,
+      replyLogger,
+      skipLog: true,
+    });
+
+    expect(msg.reply).not.toHaveBeenCalled();
+    expect(msg.sendMedia).not.toHaveBeenCalled();
+  });
+
+  it("suppresses payloads that start with reasoning prefix text", async () => {
+    const msg = makeMsg();
+
+    await deliverWebReply({
+      replyResult: { text: "   \n Reasoning:\n_hidden_" },
+      msg,
+      maxMediaBytes: 1024 * 1024,
+      textLimit: 200,
+      replyLogger,
+      skipLog: true,
+    });
+
+    expect(msg.reply).not.toHaveBeenCalled();
+    expect(msg.sendMedia).not.toHaveBeenCalled();
+  });
+
+  it("does not suppress messages that mention Reasoning: mid-text", async () => {
+    const msg = makeMsg();
+
+    await deliverWebReply({
+      replyResult: { text: "Intro line\nReasoning: appears in content but is not a prefix" },
+      msg,
+      maxMediaBytes: 1024 * 1024,
+      textLimit: 200,
+      replyLogger,
+      skipLog: true,
+    });
+
+    expect(msg.reply).toHaveBeenCalledTimes(1);
+    expect(msg.reply).toHaveBeenCalledWith(
+      "Intro line\nReasoning: appears in content but is not a prefix",
+    );
+  });
+
   it("sends chunked text replies and logs a summary", async () => {
     const msg = makeMsg();
 

src/web/auto-reply/deliver-reply.ts

@@ -12,6 +12,19 @@ import { whatsappOutboundLog } from "./loggers.js";
 import type { WebInboundMsg } from "./types.js";
 import { elide } from "./util.js";
 
+const REASONING_PREFIX = "reasoning:";
+
+function shouldSuppressReasoningReply(payload: ReplyPayload): boolean {
+  if (payload.isReasoning === true) {
+    return true;
+  }
+  const text = payload.text;
+  if (typeof text !== "string") {
+    return false;
+  }
+  return text.trimStart().toLowerCase().startsWith(REASONING_PREFIX);
+}
+
 export async function deliverWebReply(params: {
   replyResult: ReplyPayload;
   msg: WebInboundMsg;
@@ -29,6 +42,10 @@ export async function deliverWebReply(params: {
 }) {
   const { replyResult, msg, maxMediaBytes, textLimit, replyLogger, connectionId, skipLog } = params;
   const replyStarted = Date.now();
+  if (shouldSuppressReasoningReply(replyResult)) {
+    whatsappOutboundLog.debug(`Suppressed reasoning payload to ${msg.from}`);
+    return;
+  }
   const tableMode = params.tableMode ?? "code";
   const chunkMode = params.chunkMode ?? "length";
   const convertedText = markdownToWhatsApp(