From e85bda87be8d2d4112647912fad53a5a23ae07a5 Mon Sep 17 00:00:00 2001
From: Tony Dehnke <tdehnke@me.com>
Date: Sat, 21 Feb 2026 13:30:42 +0000
Subject: [PATCH] =?UTF-8?q?fix(mattermost):=20restore=202D=E2=86=921D=20bu?=
 =?UTF-8?q?tton=20flattening=20and=20empty-name=20filter?=
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The core sends buttons as Array<Array<Button>> (2D for Telegram row
layout). The consolidation from #18151 into #19957 lost the flatMap
that flattens to 1D and the .filter() that drops malformed buttons.

Without flatMap, each "button" is actually a row array — btn.text is
undefined, producing empty-name buttons that render as white boxes
with a blue left border in Mattermost.
---
 extensions/mattermost/src/channel.ts | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/extensions/mattermost/src/channel.ts b/extensions/mattermost/src/channel.ts
index b151ed708d9..401ddabf38b 100644
--- a/extensions/mattermost/src/channel.ts
+++ b/extensions/mattermost/src/channel.ts
@@ -167,15 +167,24 @@ const mattermostMessageActions: ChannelMessageActionAdapter = {
       if (account.botToken) setInteractionSecret(account.botToken);
       const callbackUrl = resolveInteractionCallbackUrl(account.accountId, cfg);
 
-      const buttons = (params.buttons as Array<Record<string, unknown>>).map((btn) => ({
-        id: String(btn.id ?? btn.callback_data ?? ""),
-        name: String(btn.text ?? btn.name ?? btn.label ?? ""),
-        style: (btn.style as "default" | "primary" | "danger") ?? "default",
-        context:
-          typeof btn.context === "object" && btn.context !== null
-            ? (btn.context as Record<string, unknown>)
-            : undefined,
-      }));
+      // Flatten 2D array (rows of buttons) to 1D — core schema sends Array<Array<Button>>
+      // but Mattermost doesn't have row layout, so we flatten all rows into a single list.
+      // Also supports 1D arrays for backward compatibility.
+      const rawButtons = (params.buttons as Array<unknown>).flatMap((item) =>
+        Array.isArray(item) ? item : [item],
+      ) as Array<Record<string, unknown>>;
+
+      const buttons = rawButtons
+        .map((btn) => ({
+          id: String(btn.id ?? btn.callback_data ?? ""),
+          name: String(btn.text ?? btn.name ?? btn.label ?? ""),
+          style: (btn.style as "default" | "primary" | "danger") ?? "default",
+          context:
+            typeof btn.context === "object" && btn.context !== null
+              ? (btn.context as Record<string, unknown>)
+              : undefined,
+        }))
+        .filter((btn) => btn.id && btn.name);
 
       const attachmentText =
         typeof params.attachmentText === "string" ? params.attachmentText : undefined;