fix(slack): send proactive dm text directly

CHANGELOG.md

@@ -46,6 +46,7 @@ Docs: https://docs.openclaw.ai
 - Slack/DMs: honor `dmHistoryLimit` for fresh 1:1 Slack DM sessions by backfilling recent conversation history before the current reply. Fixes #64427. Thanks @brantley-creator.
 - Slack/DMs: keep top-level direct messages on the stable DM session even when `replyToMode` targets Slack thread replies, preserving context across DM turns. Fixes #58832. Thanks @daye-jjeong.
 - Slack/delivery: preserve Slack Web API missing-scope details in outbound delivery errors, so queued retry state identifies the OAuth scope to add. Fixes #62391. Thanks @alexey-pelykh.
+- Slack/DMs: send text/block-only proactive DMs directly with `chat.postMessage(channel=<user id>)` while keeping conversation resolution for uploads and threaded sends. Fixes #62042. Thanks @MarkMolina.
 - Slack/mentions: resolve `<!subteam^...>` user-group mentions through Slack `usergroups.users.list` and treat them as explicit mentions only when the bot user is a member, so mention-gated agent channels wake for real user-group mentions without config-only allowlists. Fixes #73827. Thanks @CG-Intelligence-Agent-Jack.
 - Slack/message tool: let `read` fetch an exact Slack message timestamp, including a specific thread reply when paired with `threadId`, instead of returning only the parent thread or recent channel history. Fixes #53943. Thanks @zomars.
 - Web search: point missing-key errors to `web_fetch` for known URLs and the browser tool for interactive pages. Thanks @zhaoyang97.

docs/channels/slack.md

@@ -714,7 +714,7 @@ Notes:
     - `user:<id>` for DMs
     - `channel:<id>` for channels
 
-    Slack DMs are opened via Slack conversation APIs when sending to user targets.
+    Text/block-only Slack DMs can post directly to user IDs; file uploads and threaded sends open the DM via Slack conversation APIs first because those paths require a concrete conversation ID.
 
   </Accordion>
 </AccordionGroup>

extensions/slack/src/send.blocks.test.ts

@@ -115,6 +115,27 @@ describe("sendMessageSlack blocks", () => {
     expect(result).toEqual({ messageId: "171234.567", channelId: "C123" });
   });
 
+  it("posts user-target block messages directly without conversations.open", async () => {
+    const client = createSlackSendTestClient();
+    client.conversations.open.mockRejectedValueOnce(new Error("missing_scope"));
+
+    const result = await sendMessageSlack("user:U123", "", {
+      token: "xoxb-test",
+      cfg: SLACK_TEST_CFG,
+      client,
+      blocks: [{ type: "divider" }],
+    });
+
+    expect(client.conversations.open).not.toHaveBeenCalled();
+    expect(client.chat.postMessage).toHaveBeenCalledWith(
+      expect.objectContaining({
+        channel: "U123",
+        text: "Shared a Block Kit message",
+      }),
+    );
+    expect(result).toEqual({ messageId: "171234.567", channelId: "U123" });
+  });
+
   it("derives fallback text from image blocks", async () => {
     const client = createSlackSendTestClient();
     await sendMessageSlack("channel:C123", "", {

extensions/slack/src/send.ts

@@ -300,6 +300,21 @@ function setSlackDmChannelCache(key: string, channelId: string): void {
   slackDmChannelCache.set(key, channelId);
 }
 
+function isSlackUserRecipient(recipient: SlackRecipient): boolean {
+  return recipient.kind === "user" || /^U[A-Z0-9]+$/i.test(recipient.id);
+}
+
+function resolveDirectUserPostChannelId(params: {
+  recipient: SlackRecipient;
+  hasMedia: boolean;
+  threadTs?: string;
+}): string | undefined {
+  if (!isSlackUserRecipient(params.recipient) || params.hasMedia || params.threadTs) {
+    return undefined;
+  }
+  return params.recipient.id;
+}
+
 async function resolveChannelId(
   client: WebClient,
   recipient: SlackRecipient,
@@ -309,10 +324,9 @@ async function resolveChannelId(
   // target string had no explicit prefix (parseSlackTarget defaults bare IDs
   // to "channel"). chat.postMessage tolerates user IDs directly, but
   // files.uploadV2 → completeUploadExternal validates channel_id against
-  // ^[CGDZ][A-Z0-9]{8,}$ and rejects U-prefixed IDs.  Always resolve user
-  // IDs via conversations.open to obtain the DM channel ID.
-  const isUserId = recipient.kind === "user" || /^U[A-Z0-9]+$/i.test(recipient.id);
-  if (!isUserId) {
+  // ^[CGDZ][A-Z0-9]{8,}$ and rejects U-prefixed IDs. Resolve user IDs via
+  // conversations.open only for paths that require the concrete DM channel ID.
+  if (!isSlackUserRecipient(recipient)) {
     return { channelId: recipient.id };
   }
   const cacheKey = createSlackDmCacheKey({
@@ -484,10 +498,17 @@ async function sendMessageSlackQueuedInner(params: {
 }): Promise<SlackSendResult> {
   const { opts, cfg, account, token, recipient, blocks, trimmedMessage } = params;
   const client = opts.client ?? getSlackWriteClient(token);
-  const { channelId } = await resolveChannelId(client, recipient, {
-    accountId: account.accountId,
-    token,
+  const directUserPostChannelId = resolveDirectUserPostChannelId({
+    recipient,
+    hasMedia: Boolean(opts.mediaUrl),
+    ...(opts.threadTs ? { threadTs: opts.threadTs } : {}),
   });
+  const { channelId } = directUserPostChannelId
+    ? { channelId: directUserPostChannelId }
+    : await resolveChannelId(client, recipient, {
+        accountId: account.accountId,
+        token,
+      });
   if (blocks) {
     if (opts.mediaUrl) {
       throw new Error("Slack send does not support blocks with mediaUrl");

extensions/slack/src/send.upload.test.ts

@@ -145,8 +145,9 @@ describe("sendMessageSlack file upload with user IDs", () => {
     );
   });
 
-  it("caches DM channel resolution per account", async () => {
+  it("posts text-only user-target DMs directly without conversations.open", async () => {
     const client = createUploadTestClient();
+    client.conversations.open.mockRejectedValueOnce(new Error("missing_scope"));
 
     await sendMessageSlack("user:UABC123", "first", {
       token: "xoxb-test",
@@ -159,12 +160,12 @@ describe("sendMessageSlack file upload with user IDs", () => {
       client,
     });
 
-    expect(client.conversations.open).toHaveBeenCalledTimes(1);
+    expect(client.conversations.open).not.toHaveBeenCalled();
     expect(client.chat.postMessage).toHaveBeenCalledTimes(2);
     expect(client.chat.postMessage).toHaveBeenNthCalledWith(
       2,
       expect.objectContaining({
-        channel: "D99RESOLVED",
+        channel: "UABC123",
         text: "second",
       }),
     );
@@ -215,11 +216,13 @@ describe("sendMessageSlack file upload with user IDs", () => {
       token: "xoxb-test-a",
       cfg: SLACK_TEST_CFG,
       client,
+      mediaUrl: "/tmp/first.png",
     });
     await sendMessageSlack("user:UABC123", "second", {
       token: "xoxb-test-b",
       cfg: SLACK_TEST_CFG,
       client,
+      mediaUrl: "/tmp/second.png",
     });
 
     expect(client.conversations.open).toHaveBeenCalledTimes(2);