diff --git a/src/auto-reply/reply/reply-flow.test.ts b/src/auto-reply/reply/reply-flow.test.ts
index 7bb4332cb8a..b46cedc59aa 100644
--- a/src/auto-reply/reply/reply-flow.test.ts
+++ b/src/auto-reply/reply/reply-flow.test.ts
@@ -782,6 +782,82 @@ describe("parseSlackDirectives", () => {
       },
     ]);
   });
+
+  it("truncates Slack interactive reply strings to safe Block Kit limits", () => {
+    const long = "x".repeat(120);
+    const result = parseSlackDirectives({
+      text: `${"y".repeat(3100)} [[slack_select: ${long} | ${long}:${long}]] [[slack_buttons: ${long}:${long}]]`,
+    });
+
+    const blocks = getSlackData(result).blocks as Array<Record<string, unknown>>;
+    expect(blocks).toHaveLength(3);
+    expect(((blocks[0]?.text as { text?: string })?.text ?? "").length).toBeLessThanOrEqual(3000);
+    expect(
+      (
+        (
+          (blocks[1]?.elements as Array<Record<string, unknown>>)?.[0]?.placeholder as {
+            text?: string;
+          }
+        )?.text ?? ""
+      ).length,
+    ).toBeLessThanOrEqual(75);
+    expect(
+      (
+        (
+          (
+            (blocks[1]?.elements as Array<Record<string, unknown>>)?.[0]?.options as Array<
+              Record<string, unknown>
+            >
+          )?.[0]?.text as { text?: string }
+        )?.text ?? ""
+      ).length,
+    ).toBeLessThanOrEqual(75);
+    expect(
+      (
+        ((
+          (blocks[1]?.elements as Array<Record<string, unknown>>)?.[0]?.options as Array<
+            Record<string, unknown>
+          >
+        )?.[0]?.value as string | undefined) ?? ""
+      ).length,
+    ).toBeLessThanOrEqual(75);
+    expect(
+      (
+        (
+          (blocks[2]?.elements as Array<Record<string, unknown>>)?.[0]?.text as {
+            text?: string;
+          }
+        )?.text ?? ""
+      ).length,
+    ).toBeLessThanOrEqual(75);
+    expect(
+      (
+        ((blocks[2]?.elements as Array<Record<string, unknown>>)?.[0]?.value as
+          | string
+          | undefined) ?? ""
+      ).length,
+    ).toBeLessThanOrEqual(75);
+  });
+
+  it("falls back to the original payload when generated blocks would exceed Slack limits", () => {
+    const result = parseSlackDirectives({
+      text: "Choose [[slack_buttons: Retry:retry]]",
+      channelData: {
+        slack: {
+          blocks: Array.from({ length: 49 }, () => ({ type: "divider" })),
+        },
+      },
+    });
+
+    expect(result).toEqual({
+      text: "Choose [[slack_buttons: Retry:retry]]",
+      channelData: {
+        slack: {
+          blocks: Array.from({ length: 49 }, () => ({ type: "divider" })),
+        },
+      },
+    });
+  });
 });
 
 function createDeferred<T>() {
diff --git a/src/auto-reply/reply/route-reply.test.ts b/src/auto-reply/reply/route-reply.test.ts
index 9b5d432149a..d5ecbdd6f2f 100644
--- a/src/auto-reply/reply/route-reply.test.ts
+++ b/src/auto-reply/reply/route-reply.test.ts
@@ -201,6 +201,35 @@ describe("routeReply", () => {
     );
   });
 
+  it("routes directive-only Slack replies when interactive replies are enabled", async () => {
+    mocks.sendMessageSlack.mockClear();
+    const cfg = {
+      channels: {
+        slack: {
+          capabilities: { interactiveReplies: true },
+        },
+      },
+    } as unknown as OpenClawConfig;
+    await routeReply({
+      payload: { text: "[[slack_select: Choose one | Alpha:alpha]]" },
+      channel: "slack",
+      to: "channel:C123",
+      cfg,
+    });
+    expect(mocks.sendMessageSlack).toHaveBeenCalledWith(
+      "channel:C123",
+      "",
+      expect.objectContaining({
+        blocks: [
+          expect.objectContaining({
+            type: "actions",
+            block_id: "openclaw_reply_select_1",
+          }),
+        ],
+      }),
+    );
+  });
+
   it("does not derive responsePrefix from agent identity when routing", async () => {
     mocks.sendMessageSlack.mockClear();
     const cfg = {
diff --git a/src/auto-reply/reply/route-reply.ts b/src/auto-reply/reply/route-reply.ts
index 981d45d0d9b..e915308f39a 100644
--- a/src/auto-reply/reply/route-reply.ts
+++ b/src/auto-reply/reply/route-reply.ts
@@ -109,9 +109,17 @@ export async function routeReply(params: RouteReplyParams): Promise<RouteReplyRe
       ? [normalized.mediaUrl]
       : [];
   const replyToId = normalized.replyToId;
+  const hasSlackBlocks =
+    channel === "slack" &&
+    Boolean(
+      normalized.channelData?.slack &&
+      typeof normalized.channelData.slack === "object" &&
+      !Array.isArray(normalized.channelData.slack) &&
+      (normalized.channelData.slack as { blocks?: unknown }).blocks,
+    );
 
   // Skip empty replies.
-  if (!text.trim() && mediaUrls.length === 0) {
+  if (!text.trim() && mediaUrls.length === 0 && !hasSlackBlocks) {
     return { ok: true };
   }
 
diff --git a/src/auto-reply/reply/slack-directives.ts b/src/auto-reply/reply/slack-directives.ts
index d56b3af87c4..268adc56a67 100644
--- a/src/auto-reply/reply/slack-directives.ts
+++ b/src/auto-reply/reply/slack-directives.ts
@@ -3,8 +3,12 @@ import type { ReplyPayload } from "../types.js";
 
 const SLACK_REPLY_BUTTON_ACTION_ID = "openclaw:reply_button";
 const SLACK_REPLY_SELECT_ACTION_ID = "openclaw:reply_select";
+const SLACK_MAX_BLOCKS = 50;
 const SLACK_BUTTON_MAX_ITEMS = 5;
 const SLACK_SELECT_MAX_ITEMS = 100;
+const SLACK_SECTION_TEXT_MAX = 3000;
+const SLACK_PLAIN_TEXT_MAX = 75;
+const SLACK_OPTION_VALUE_MAX = 75;
 const SLACK_DIRECTIVE_RE = /\[\[(slack_buttons|slack_select):\s*([^\]]+)\]\]/gi;
 
 type SlackBlock = Record<string, unknown>;
@@ -17,6 +21,17 @@ type SlackChoice = {
   value: string;
 };
 
+function truncateSlackText(value: string, max: number): string {
+  const trimmed = value.trim();
+  if (trimmed.length <= max) {
+    return trimmed;
+  }
+  if (max <= 1) {
+    return trimmed.slice(0, max);
+  }
+  return `${trimmed.slice(0, max - 1)}…`;
+}
+
 function parseChoice(raw: string): SlackChoice | null {
   const trimmed = raw.trim();
   if (!trimmed) {
@@ -54,7 +69,7 @@ function buildSectionBlock(text: string): SlackBlock | null {
     type: "section",
     text: {
       type: "mrkdwn",
-      text: trimmed,
+      text: truncateSlackText(trimmed, SLACK_SECTION_TEXT_MAX),
     },
   };
 }
@@ -72,10 +87,10 @@ function buildButtonsBlock(raw: string, index: number): SlackBlock | null {
       action_id: SLACK_REPLY_BUTTON_ACTION_ID,
       text: {
         type: "plain_text",
-        text: choice.label,
+        text: truncateSlackText(choice.label, SLACK_PLAIN_TEXT_MAX),
         emoji: true,
       },
-      value: choice.value,
+      value: truncateSlackText(choice.value, SLACK_OPTION_VALUE_MAX),
     })),
   };
 }
@@ -103,16 +118,16 @@ function buildSelectBlock(raw: string, index: number): SlackBlock | null {
         action_id: SLACK_REPLY_SELECT_ACTION_ID,
         placeholder: {
           type: "plain_text",
-          text: placeholder,
+          text: truncateSlackText(placeholder, SLACK_PLAIN_TEXT_MAX),
           emoji: true,
         },
         options: choices.map((choice) => ({
           text: {
             type: "plain_text",
-            text: choice.label,
+            text: truncateSlackText(choice.label, SLACK_PLAIN_TEXT_MAX),
             emoji: true,
           },
-          value: choice.value,
+          value: truncateSlackText(choice.value, SLACK_OPTION_VALUE_MAX),
         })),
       },
     ],
@@ -181,6 +196,9 @@ export function parseSlackDirectives(payload: ReplyPayload): ReplyPayload {
   }
 
   const existingBlocks = readExistingSlackBlocks(payload);
+  if (existingBlocks.length + generatedBlocks.length > SLACK_MAX_BLOCKS) {
+    return payload;
+  }
   const nextBlocks = [...existingBlocks, ...generatedBlocks];
 
   return {