diff --git a/src/auto-reply/chunk.ts b/src/auto-reply/chunk.ts
index e91b9e8683..a40eebb82c 100644
--- a/src/auto-reply/chunk.ts
+++ b/src/auto-reply/chunk.ts
@@ -6,6 +6,7 @@ import type { ChannelId } from "../channels/plugins/types.js";
 import type { OpenClawConfig } from "../config/config.js";
 import { findFenceSpanAt, isSafeFenceBreak, parseFenceSpans } from "../markdown/fences.js";
 import { normalizeAccountId } from "../routing/session-key.js";
+import { chunkTextByBreakResolver } from "../shared/text-chunking.js";
 import { INTERNAL_MESSAGE_CHANNEL } from "../utils/message-channel.js";
 
 export type TextChunkProvider = ChannelId | typeof INTERNAL_MESSAGE_CHANNEL;
@@ -316,41 +317,12 @@ export function chunkText(text: string, limit: number): string[] {
   if (early) {
     return early;
   }
-
-  const chunks: string[] = [];
-  let remaining = text;
-
-  while (remaining.length > limit) {
-    const window = remaining.slice(0, limit);
-
+  return chunkTextByBreakResolver(text, limit, (window) => {
     // 1) Prefer a newline break inside the window (outside parentheses).
     const { lastNewline, lastWhitespace } = scanParenAwareBreakpoints(window);
-
     // 2) Otherwise prefer the last whitespace (word boundary) inside the window.
-    let breakIdx = lastNewline > 0 ? lastNewline : lastWhitespace;
-
-    // 3) Fallback: hard break exactly at the limit.
-    if (breakIdx <= 0) {
-      breakIdx = limit;
-    }
-
-    const rawChunk = remaining.slice(0, breakIdx);
-    const chunk = rawChunk.trimEnd();
-    if (chunk.length > 0) {
-      chunks.push(chunk);
-    }
-
-    // If we broke on whitespace/newline, skip that separator; for hard breaks keep it.
-    const brokeOnSeparator = breakIdx < remaining.length && /\s/.test(remaining[breakIdx]);
-    const nextStart = Math.min(remaining.length, breakIdx + (brokeOnSeparator ? 1 : 0));
-    remaining = remaining.slice(nextStart).trimStart();
-  }
-
-  if (remaining.length) {
-    chunks.push(remaining);
-  }
-
-  return chunks;
+    return lastNewline > 0 ? lastNewline : lastWhitespace;
+  });
 }
 
 export function chunkMarkdownText(text: string, limit: number): string[] {
diff --git a/src/plugin-sdk/text-chunking.test.ts b/src/plugin-sdk/text-chunking.test.ts
new file mode 100644
index 0000000000..b96b00cd99
--- /dev/null
+++ b/src/plugin-sdk/text-chunking.test.ts
@@ -0,0 +1,16 @@
+import { describe, expect, it } from "vitest";
+import { chunkTextForOutbound } from "./text-chunking.js";
+
+describe("chunkTextForOutbound", () => {
+  it("returns empty for empty input", () => {
+    expect(chunkTextForOutbound("", 10)).toEqual([]);
+  });
+
+  it("splits on newline or whitespace boundaries", () => {
+    expect(chunkTextForOutbound("alpha\nbeta gamma", 8)).toEqual(["alpha", "beta", "gamma"]);
+  });
+
+  it("falls back to hard limit when no separator exists", () => {
+    expect(chunkTextForOutbound("abcdefghij", 4)).toEqual(["abcd", "efgh", "ij"]);
+  });
+});
diff --git a/src/plugin-sdk/text-chunking.ts b/src/plugin-sdk/text-chunking.ts
index 3c86e43f6f..47c98c1085 100644
--- a/src/plugin-sdk/text-chunking.ts
+++ b/src/plugin-sdk/text-chunking.ts
@@ -1,31 +1,9 @@
+import { chunkTextByBreakResolver } from "../shared/text-chunking.js";
+
 export function chunkTextForOutbound(text: string, limit: number): string[] {
-  if (!text) {
-    return [];
-  }
-  if (limit <= 0 || text.length <= limit) {
-    return [text];
-  }
-  const chunks: string[] = [];
-  let remaining = text;
-  while (remaining.length > limit) {
-    const window = remaining.slice(0, limit);
+  return chunkTextByBreakResolver(text, limit, (window) => {
     const lastNewline = window.lastIndexOf("\n");
     const lastSpace = window.lastIndexOf(" ");
-    let breakIdx = lastNewline > 0 ? lastNewline : lastSpace;
-    if (breakIdx <= 0) {
-      breakIdx = limit;
-    }
-    const rawChunk = remaining.slice(0, breakIdx);
-    const chunk = rawChunk.trimEnd();
-    if (chunk.length > 0) {
-      chunks.push(chunk);
-    }
-    const brokeOnSeparator = breakIdx < remaining.length && /\s/.test(remaining[breakIdx]);
-    const nextStart = Math.min(remaining.length, breakIdx + (brokeOnSeparator ? 1 : 0));
-    remaining = remaining.slice(nextStart).trimStart();
-  }
-  if (remaining.length) {
-    chunks.push(remaining);
-  }
-  return chunks;
+    return lastNewline > 0 ? lastNewline : lastSpace;
+  });
 }
diff --git a/src/shared/text-chunking.ts b/src/shared/text-chunking.ts
new file mode 100644
index 0000000000..9b75368fcd
--- /dev/null
+++ b/src/shared/text-chunking.ts
@@ -0,0 +1,34 @@
+export function chunkTextByBreakResolver(
+  text: string,
+  limit: number,
+  resolveBreakIndex: (window: string) => number,
+): string[] {
+  if (!text) {
+    return [];
+  }
+  if (limit <= 0 || text.length <= limit) {
+    return [text];
+  }
+  const chunks: string[] = [];
+  let remaining = text;
+  while (remaining.length > limit) {
+    const window = remaining.slice(0, limit);
+    const candidateBreak = resolveBreakIndex(window);
+    const breakIdx =
+      Number.isFinite(candidateBreak) && candidateBreak > 0 && candidateBreak <= limit
+        ? candidateBreak
+        : limit;
+    const rawChunk = remaining.slice(0, breakIdx);
+    const chunk = rawChunk.trimEnd();
+    if (chunk.length > 0) {
+      chunks.push(chunk);
+    }
+    const brokeOnSeparator = breakIdx < remaining.length && /\s/.test(remaining[breakIdx]);
+    const nextStart = Math.min(remaining.length, breakIdx + (brokeOnSeparator ? 1 : 0));
+    remaining = remaining.slice(nextStart).trimStart();
+  }
+  if (remaining.length) {
+    chunks.push(remaining);
+  }
+  return chunks;
+}