fix(slack): truncate served arg-menu option labels on a surrogate boundary (#97923)

LEXES7 · web-flow · commit 5113fbf4cc6a · 2026-07-01T03:12:56.000-07:00
diff --git a/extensions/slack/src/monitor/slash.test.ts b/extensions/slack/src/monitor/slash.test.ts
@@ -215,10 +215,15 @@ vi.mock("./slash-commands.runtime.js", () => {
       if (params.command?.key === "reportexternal") {
         return {
           arg: { name: "period", description: "period" },
-          choices: Array.from({ length: 140 }, (_v, i) => ({
-            value: `period-${i + 1}`,
-            label: `Period ${i + 1}`,
-          })),
+          choices: [
+            ...Array.from({ length: 140 }, (_v, i) => ({
+              value: `period-${i + 1}`,
+              label: `Period ${i + 1}`,
+            })),
+            // Label whose emoji surrogate pair straddles the 75-char plain_text
+            // limit, to cover surrogate-safe truncation in served options.
+            { value: "emoji-overflow", label: `${"a".repeat(74)}😀 emojioverflow` },
+          ],
         };
       }
       if (params.command?.key === "unsafeconfirm") {
@@ -872,6 +877,37 @@ describe("Slack native command argument menus", () => {
     expect(optionTexts.join("\n")).toContain("Period 12");
   });
 
+  it("truncates served option labels on a surrogate boundary", async () => {
+    const { blockId } = await runCommandAndResolveActionsBlock(reportExternalHandler);
+    expect(blockId).toContain("openclaw_cmdarg_ext:");
+
+    const ackOptions = vi.fn().mockResolvedValue(undefined);
+    await argMenuOptionsHandler({
+      ack: ackOptions,
+      body: {
+        user: { id: "U1" },
+        value: "emojioverflow",
+        actions: [{ block_id: blockId }],
+      },
+    });
+
+    const optionsPayload = firstCallPayload(ackOptions, "options ack") as {
+      options?: Array<{ text?: { text?: string }; value?: string }>;
+    };
+    // The "emojioverflow" query matches only the long emoji label, so exactly one
+    // option is served.
+    const served = optionsPayload.options ?? [];
+    expect(served).toHaveLength(1);
+    const text = served[0]?.text?.text ?? "";
+    // Plain_text option labels are capped at 75 chars and must not end on a lone
+    // surrogate half, which Slack rejects. The label was long enough to truncate.
+    expect(text.length).toBeGreaterThan(0);
+    expect(text.length).toBeLessThanOrEqual(75);
+    expect(
+      /[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]/.test(text),
+    ).toBe(false);
+  });
+
   it("tracks accepted external_select option requests", async () => {
     const trackingHarness = createArgMenusHarness();
     const trackEvent = vi.fn();
diff --git a/extensions/slack/src/monitor/slash.ts b/extensions/slack/src/monitor/slash.ts
@@ -931,7 +931,13 @@ export async function registerSlackMonitorSlashCommands(params: {
         .filter((choice) => !query || normalizeLowercaseStringOrEmpty(choice.label).includes(query))
         .slice(0, SLACK_COMMAND_ARG_SELECT_OPTIONS_MAX)
         .map((choice) => ({
-          text: { type: "plain_text", text: choice.label.slice(0, 75) },
+          // Surrogate-safe cap (matches the static-select path above) so an emoji
+          // straddling the 75-char Slack plain_text limit is dropped whole rather
+          // than serialized as a lone `\uD83D` half that Slack rejects.
+          text: {
+            type: "plain_text",
+            text: truncateSlackText(choice.label, SLACK_COMMAND_ARG_SELECT_OPTION_TEXT_MAX),
+          },
           value: choice.value,
         }));
       await ack({ options });
