fix: newline chunking across channels

extensions/mattermost/src/channel.ts

@@ -158,6 +158,7 @@ export const mattermostPlugin: ChannelPlugin<ResolvedMattermostAccount> = {
   outbound: {
     deliveryMode: "direct",
     chunker: (text, limit) => getMattermostRuntime().channel.text.chunkMarkdownText(text, limit),
+    chunkerMode: "markdown",
     textChunkLimit: 4000,
     resolveTarget: ({ to }) => {
       const trimmed = to?.trim();

extensions/mattermost/src/config-schema.ts

@@ -25,6 +25,7 @@ const MattermostAccountSchemaBase = z
     groupAllowFrom: z.array(z.union([z.string(), z.number()])).optional(),
     groupPolicy: GroupPolicySchema.optional().default("allowlist"),
     textChunkLimit: z.number().int().positive().optional(),
+    chunkMode: z.enum(["length", "newline"]).optional(),
     blockStreaming: z.boolean().optional(),
     blockStreamingCoalesce: BlockStreamingCoalesceSchema.optional(),
   })

extensions/mattermost/src/mattermost/monitor.ts

@@ -738,7 +738,12 @@ export async function monitorMattermostProvider(opts: MonitorMattermostOpts = {}
           const mediaUrls = payload.mediaUrls ?? (payload.mediaUrl ? [payload.mediaUrl] : []);
           const text = core.channel.text.convertMarkdownTables(payload.text ?? "", tableMode);
           if (mediaUrls.length === 0) {
-            const chunks = core.channel.text.chunkMarkdownText(text, textLimit);
+            const chunkMode = core.channel.text.resolveChunkMode(
+              cfg,
+              "mattermost",
+              account.accountId,
+            );
+            const chunks = core.channel.text.chunkMarkdownTextWithMode(text, textLimit, chunkMode);
             for (const chunk of chunks.length > 0 ? chunks : [text]) {
               if (!chunk) continue;
               await sendMessageMattermost(to, chunk, {

extensions/mattermost/src/types.ts

@@ -36,6 +36,8 @@ export type MattermostAccountConfig = {
   groupPolicy?: GroupPolicy;
   /** Outbound text chunk size (chars). Default: 4000. */
   textChunkLimit?: number;
+  /** Chunking mode: "length" (default) splits by size; "newline" splits on every newline. */
+  chunkMode?: "length" | "newline";
   /** Disable block streaming for this account. */
   blockStreaming?: boolean;
   /** Merge streamed block replies before sending. */