diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0cb82299c..56c821e60 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,9 @@ Docs: https://docs.clawd.bot
 - Android: remove legacy bridge transport code now that nodes use the gateway protocol.
 - Android: send structured payloads in node events/invokes and include user-agent metadata in gateway connects.
 
+### Fixes
+- Gateway: strip inbound envelope headers from chat history messages to keep clients clean.
+
 ## 2026.1.19-2
 
 ### Changes
diff --git a/src/gateway/chat-sanitize.ts b/src/gateway/chat-sanitize.ts
new file mode 100644
index 000000000..398fabf1f
--- /dev/null
+++ b/src/gateway/chat-sanitize.ts
@@ -0,0 +1,89 @@
+const ENVELOPE_PREFIX = /^\[([^\]]+)\]\s*/;
+const ENVELOPE_CHANNELS = [
+  "WebChat",
+  "WhatsApp",
+  "Telegram",
+  "Signal",
+  "Slack",
+  "Discord",
+  "iMessage",
+  "Teams",
+  "Matrix",
+  "Zalo",
+  "Zalo Personal",
+  "BlueBubbles",
+];
+
+function looksLikeEnvelopeHeader(header: string): boolean {
+  if (/\d{4}-\d{2}-\d{2}T\d{2}:\d{2}Z\b/.test(header)) return true;
+  if (/\d{4}-\d{2}-\d{2} \d{2}:\d{2}\b/.test(header)) return true;
+  return ENVELOPE_CHANNELS.some((label) => header.startsWith(`${label} `));
+}
+
+export function stripEnvelope(text: string): string {
+  const match = text.match(ENVELOPE_PREFIX);
+  if (!match) return text;
+  const header = match[1] ?? "";
+  if (!looksLikeEnvelopeHeader(header)) return text;
+  return text.slice(match[0].length);
+}
+
+function stripEnvelopeFromContent(content: unknown[]): { content: unknown[]; changed: boolean } {
+  let changed = false;
+  const next = content.map((item) => {
+    if (!item || typeof item !== "object") return item;
+    const entry = item as Record<string, unknown>;
+    if (entry.type !== "text" || typeof entry.text !== "string") return item;
+    const stripped = stripEnvelope(entry.text);
+    if (stripped === entry.text) return item;
+    changed = true;
+    return {
+      ...entry,
+      text: stripped,
+    };
+  });
+  return { content: next, changed };
+}
+
+export function stripEnvelopeFromMessage(message: unknown): unknown {
+  if (!message || typeof message !== "object") return message;
+  const entry = message as Record<string, unknown>;
+  const role = typeof entry.role === "string" ? entry.role.toLowerCase() : "";
+  if (role !== "user") return message;
+
+  let changed = false;
+  const next: Record<string, unknown> = { ...entry };
+
+  if (typeof entry.content === "string") {
+    const stripped = stripEnvelope(entry.content);
+    if (stripped !== entry.content) {
+      next.content = stripped;
+      changed = true;
+    }
+  } else if (Array.isArray(entry.content)) {
+    const updated = stripEnvelopeFromContent(entry.content);
+    if (updated.changed) {
+      next.content = updated.content;
+      changed = true;
+    }
+  } else if (typeof entry.text === "string") {
+    const stripped = stripEnvelope(entry.text);
+    if (stripped !== entry.text) {
+      next.text = stripped;
+      changed = true;
+    }
+  }
+
+  return changed ? next : message;
+}
+
+export function stripEnvelopeFromMessages(messages: unknown[]): unknown[] {
+  if (messages.length === 0) return messages;
+  let changed = false;
+  const next = messages.map((message) => {
+    const stripped = stripEnvelopeFromMessage(message);
+    if (stripped !== message) changed = true;
+    return stripped;
+  });
+  return changed ? next : messages;
+}
diff --git a/src/gateway/server-methods/chat.ts b/src/gateway/server-methods/chat.ts
index 7ba466e9f..92fd5f16a 100644
--- a/src/gateway/server-methods/chat.ts
+++ b/src/gateway/server-methods/chat.ts
@@ -35,6 +35,7 @@ import {
   readSessionMessages,
   resolveSessionModelRef,
 } from "../session-utils.js";
+import { stripEnvelopeFromMessages } from "../chat-sanitize.js";
 import { formatForLog } from "../ws-log.js";
 import type { GatewayRequestHandlers } from "./types.js";
 
@@ -64,7 +65,8 @@ export const chatHandlers: GatewayRequestHandlers = {
     const requested = typeof limit === "number" ? limit : defaultLimit;
     const max = Math.min(hardMax, requested);
     const sliced = rawMessages.length > max ? rawMessages.slice(-max) : rawMessages;
-    const capped = capArrayByJsonBytes(sliced, MAX_CHAT_HISTORY_MESSAGES_BYTES).items;
+    const sanitized = stripEnvelopeFromMessages(sliced);
+    const capped = capArrayByJsonBytes(sanitized, MAX_CHAT_HISTORY_MESSAGES_BYTES).items;
     let thinkingLevel = entry?.thinkingLevel;
     if (!thinkingLevel) {
       const configured = cfg.agents?.defaults?.thinkingDefault;
diff --git a/src/gateway/server.chat.gateway-server-chat.test.ts b/src/gateway/server.chat.gateway-server-chat.test.ts
index 3e21ced55..766212b74 100644
--- a/src/gateway/server.chat.gateway-server-chat.test.ts
+++ b/src/gateway/server.chat.gateway-server-chat.test.ts
@@ -303,6 +303,47 @@ describe("gateway server chat", () => {
     await server.close();
   });
 
+  test("chat.history strips inbound envelopes for user messages", async () => {
+    const dir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-gw-"));
+    testState.sessionStorePath = path.join(dir, "sessions.json");
+    await writeSessionStore({
+      entries: {
+        main: {
+          sessionId: "sess-main",
+          updatedAt: Date.now(),
+        },
+      },
+    });
+
+    const enveloped = "[WebChat agent:main:main +2m 2026-01-19 09:29 UTC] hello world";
+    await fs.writeFile(
+      path.join(dir, "sess-main.jsonl"),
+      JSON.stringify({
+        message: {
+          role: "user",
+          content: [{ type: "text", text: enveloped }],
+          timestamp: Date.now(),
+        },
+      }),
+      "utf-8",
+    );
+
+    const { server, ws } = await startServerWithClient();
+    await connectOk(ws);
+
+    const res = await rpcReq<{ messages?: unknown[] }>(ws, "chat.history", {
+      sessionKey: "main",
+    });
+    expect(res.ok).toBe(true);
+    const message = (res.payload?.messages ?? [])[0] as
+      | { content?: Array<{ text?: string }> }
+      | undefined;
+    expect(message?.content?.[0]?.text).toBe("hello world");
+
+    ws.close();
+    await server.close();
+  });
+
   test("chat.history prefers sessionFile when set", async () => {
     const dir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-gw-"));
     testState.sessionStorePath = path.join(dir, "sessions.json");