diff --git a/extensions/nostr/src/channel.outbound.test.ts b/extensions/nostr/src/channel.outbound.test.ts
index 12fb56045258..4e5666e1379f 100644
--- a/extensions/nostr/src/channel.outbound.test.ts
+++ b/extensions/nostr/src/channel.outbound.test.ts
@@ -126,6 +126,52 @@ describe("nostr outbound cfg threading", () => {
     expect(sanitizeText({ text, payload: { text } })).toBe(expected);
   });
 
+  it.each([
+    {
+      name: "preserves a short reply as one encrypted message",
+      text: "Hello from Nostr.",
+      expectedChunkCount: 1,
+      joinWith: "",
+    },
+    {
+      name: "splits long replies at word boundaries",
+      text: `${"word ".repeat(1_200)}final`,
+      expectedChunkCount: 2,
+      joinWith: " ",
+    },
+    {
+      name: "preserves newline-delimited reply order",
+      text: `${"line\n".repeat(1_200)}final`,
+      expectedChunkCount: 2,
+      joinWith: "\n",
+    },
+    {
+      name: "hard-splits an uninterrupted oversized reply",
+      text: "x".repeat(8_001),
+      expectedChunkCount: 3,
+      joinWith: "",
+    },
+    {
+      name: "preserves Unicode when an odd prefix shifts the chunk boundary",
+      text: `a${"😀".repeat(2_500)}`,
+      expectedChunkCount: 2,
+      joinWith: "",
+    },
+  ])("$name", ({ text, expectedChunkCount, joinWith }) => {
+    const outbound = nostrPlugin.outbound;
+    const textChunkLimit = outbound?.textChunkLimit;
+    expect(textChunkLimit).toBe(4_000);
+    expect(outbound?.chunker).toBeTypeOf("function");
+    if (!outbound?.chunker || textChunkLimit === undefined) {
+      throw new Error("Expected Nostr outbound text chunking");
+    }
+
+    const chunks = outbound.chunker(text, textChunkLimit);
+    expect(chunks).toHaveLength(expectedChunkCount);
+    expect(chunks.every((chunk) => chunk.length <= textChunkLimit)).toBe(true);
+    expect(chunks.join(joinWith)).toBe(text);
+  });
+
   it("converts tables before projecting markdown to Nostr plain text", async () => {
     const { resolveMarkdownTableMode, convertMarkdownTables } = installOutboundRuntime(
       vi.fn((text: string) => (text === "***" ? text : "**Table:** [docs](https://example.com)")),
diff --git a/extensions/nostr/src/gateway.ts b/extensions/nostr/src/gateway.ts
index 4cdb37d5597a..2b063a73b6fe 100644
--- a/extensions/nostr/src/gateway.ts
+++ b/extensions/nostr/src/gateway.ts
@@ -10,7 +10,11 @@ import {
 import { createChannelPairingController } from "openclaw/plugin-sdk/channel-pairing";
 import { attachChannelToResult } from "openclaw/plugin-sdk/channel-send-result";
 import type { OpenClawConfig } from "openclaw/plugin-sdk/config-contracts";
-import { sanitizeAssistantVisibleText, stripMarkdown } from "openclaw/plugin-sdk/text-chunking";
+import {
+  chunkTextForOutbound,
+  sanitizeAssistantVisibleText,
+  stripMarkdown,
+} from "openclaw/plugin-sdk/text-chunking";
 import type { ChannelOutboundAdapter, ChannelPlugin } from "./channel-api.js";
 import type { MetricEvent, MetricsSnapshot } from "./metrics.js";
 import { startNostrBus, type NostrBusHandle } from "./nostr-bus.js";
@@ -23,7 +27,7 @@ type NostrGatewayStart = NonNullable<
 >;
 type NostrOutboundAdapter = Pick<
   ChannelOutboundAdapter,
-  "deliveryCapabilities" | "deliveryMode" | "textChunkLimit" | "sendText"
+  "chunker" | "deliveryCapabilities" | "deliveryMode" | "textChunkLimit" | "sendText"
 > & {
   sendText: NonNullable<ChannelOutboundAdapter["sendText"]>;
   sanitizeText: NonNullable<ChannelOutboundAdapter["sanitizeText"]>;
@@ -316,6 +320,9 @@ export const nostrPairingTextAdapter = {
 export const nostrOutboundAdapter: NostrOutboundAdapter = {
   deliveryMode: "direct",
   textChunkLimit: 4000,
+  // The outbound planner ignores textChunkLimit unless the adapter also
+  // supplies its chunker, causing oversized encrypted events to be rejected.
+  chunker: chunkTextForOutbound,
   sanitizeText: ({ text }) => sanitizeAssistantVisibleText(text),
   deliveryCapabilities: {
     durableFinal: {