diff --git a/src/auto-reply/envelope.ts b/src/auto-reply/envelope.ts
index 000a1ecdf..a3e0ba1fe 100644
--- a/src/auto-reply/envelope.ts
+++ b/src/auto-reply/envelope.ts
@@ -59,6 +59,27 @@ export function formatInboundEnvelope(params: {
   });
 }
 
+export function formatInboundFromLabel(params: {
+  isGroup: boolean;
+  groupLabel?: string;
+  groupId?: string;
+  directLabel: string;
+  directId?: string;
+  groupFallback?: string;
+}): string {
+  // Keep envelope headers compact: group labels include id, DMs only add id when it differs.
+  if (params.isGroup) {
+    const label = params.groupLabel?.trim() || params.groupFallback || "Group";
+    const id = params.groupId?.trim();
+    return id ? `${label} id:${id}` : label;
+  }
+
+  const directLabel = params.directLabel.trim();
+  const directId = params.directId?.trim();
+  if (!directId || directId === directLabel) return directLabel;
+  return `${directLabel} id:${directId}`;
+}
+
 export function formatThreadStarterEnvelope(params: {
   channel: string;
   author?: string;
diff --git a/src/auto-reply/reply/inbound-sender-meta.test.ts b/src/auto-reply/reply/inbound-sender-meta.test.ts
index 9b1208223..2bc8d3d86 100644
--- a/src/auto-reply/reply/inbound-sender-meta.test.ts
+++ b/src/auto-reply/reply/inbound-sender-meta.test.ts
@@ -46,4 +46,11 @@ describe("formatInboundBodyWithSenderMeta", () => {
     const ctx: MsgContext = { ChatType: "group", SenderName: "Alice", SenderId: "A1" };
     expect(formatInboundBodyWithSenderMeta({ ctx, body: "Alice (A1): hi" })).toBe("Alice (A1): hi");
   });
+
+  it("does not append when the sender prefix follows an envelope header", () => {
+    const ctx: MsgContext = { ChatType: "group", SenderName: "Alice", SenderId: "A1" };
+    expect(formatInboundBodyWithSenderMeta({ ctx, body: "[Signal Group] Alice (A1): hi" })).toBe(
+      "[Signal Group] Alice (A1): hi",
+    );
+  });
 });
diff --git a/src/imessage/monitor/monitor-provider.ts b/src/imessage/monitor/monitor-provider.ts
index 229eed5da..7add40386 100644
--- a/src/imessage/monitor/monitor-provider.ts
+++ b/src/imessage/monitor/monitor-provider.ts
@@ -11,7 +11,7 @@ import {
 } from "../../auto-reply/reply/response-prefix-template.js";
 import { resolveTextChunkLimit } from "../../auto-reply/chunk.js";
 import { hasControlCommand } from "../../auto-reply/command-detection.js";
-import { formatInboundEnvelope } from "../../auto-reply/envelope.js";
+import { formatInboundEnvelope, formatInboundFromLabel } from "../../auto-reply/envelope.js";
 import {
   createInboundDebouncer,
   resolveInboundDebounceMs,
@@ -383,13 +383,14 @@ export async function monitorIMessageProvider(opts: MonitorIMessageOpts = {}): P
     }
 
     const chatTarget = formatIMessageChatTarget(chatId);
-    // For groups: use chat name or just "Group" (channel "iMessage" is already shown).
-    // For DMs: keep headers compact; only add id: suffix if raw differs from normalized.
-    const fromLabel = isGroup
-      ? `${message.chat_name || "Group"} id:${chatId ?? "unknown"}`
-      : senderNormalized === sender
-        ? senderNormalized
-        : `${senderNormalized} id:${sender}`;
+    const fromLabel = formatInboundFromLabel({
+      isGroup,
+      groupLabel: message.chat_name ?? undefined,
+      groupId: chatId !== undefined ? String(chatId) : "unknown",
+      groupFallback: "Group",
+      directLabel: senderNormalized,
+      directId: sender,
+    });
     const body = formatInboundEnvelope({
       channel: "iMessage",
       from: fromLabel,
diff --git a/src/signal/monitor/event-handler.ts b/src/signal/monitor/event-handler.ts
index e53179afa..d17841504 100644
--- a/src/signal/monitor/event-handler.ts
+++ b/src/signal/monitor/event-handler.ts
@@ -8,7 +8,7 @@ import {
   type ResponsePrefixContext,
 } from "../../auto-reply/reply/response-prefix-template.js";
 import { hasControlCommand } from "../../auto-reply/command-detection.js";
-import { formatInboundEnvelope } from "../../auto-reply/envelope.js";
+import { formatInboundEnvelope, formatInboundFromLabel } from "../../auto-reply/envelope.js";
 import {
   createInboundDebouncer,
   resolveInboundDebounceMs,
@@ -65,13 +65,14 @@ export function createSignalEventHandler(deps: SignalEventHandlerDeps) {
   };
 
   async function handleSignalInboundMessage(entry: SignalInboundEntry) {
-    // For groups: use group name or just "Group" (channel "Signal" is already shown).
-    // For DMs: keep headers compact; only add id: suffix if display differs from name.
-    const fromLabel = entry.isGroup
-      ? `${entry.groupName || "Group"} id:${entry.groupId}`
-      : entry.senderName === entry.senderDisplay
-        ? entry.senderName
-        : `${entry.senderName} id:${entry.senderDisplay}`;
+    const fromLabel = formatInboundFromLabel({
+      isGroup: entry.isGroup,
+      groupLabel: entry.groupName ?? undefined,
+      groupId: entry.groupId ?? "unknown",
+      groupFallback: "Group",
+      directLabel: entry.senderName,
+      directId: entry.senderDisplay,
+    });
     const body = formatInboundEnvelope({
       channel: "Signal",
       from: fromLabel,