fix(slack): preserve real thread anchors

CHANGELOG.md

@@ -18,6 +18,7 @@ Docs: https://docs.openclaw.ai
 - Slack/native streaming: suppress reasoning-only payloads before `chat.startStream`/`appendStream`, so Claude extended-thinking blocks no longer appear as visible Slack messages. Fixes #59687. Thanks @vision-ifc.
 - Slack/block replies: keep multi-part block deliveries in the first Slack reply thread when `replyToMode` is `first`, matching text reply threading instead of leaking later blocks into the channel. Fixes #49341. Thanks @pholmstr and @xiwuqi.
 - Slack/thread broadcasts: process `thread_broadcast` events as user messages so replies sent with "Also send to channel" reach the agent instead of becoming metadata-only system events. Fixes #56605 and #4351. Thanks @clawSean and @jlowin.
+- Slack/threading: ignore internal reply ids when choosing Slack `thread_ts` values, so resumed replies keep the real Slack thread anchor instead of leaking to the channel root. Fixes #68790. Thanks @MonkeyLeeT and @martingarramon.
 - Agents/failover: stop body-less HTTP 400/422 proxy failures from defaulting to `"format"` classification, so embedded retries surface the opaque provider failure instead of falling into a compaction loop. Fixes #66462. (#67024) Thanks @altaywtf and @HongzhuLiu.
 - Plugins/loader: use cached discovery-mode snapshot loads for read-only plugin capability lookups, keep snapshot caches isolated from active Gateway registries, and make same-plugin channel/HTTP route re-registration idempotent so repeated snapshot or hot-reload paths no longer rerun full plugin side effects or accumulate duplicate surfaces. Fixes #51781, #52031, #54181, and #57514. Thanks @livingghost, @okuyam2y, @ShionEria, and @bbshih.
 - Plugins/loader: reuse the compatible active Gateway registry for broad runtime plugin ensure calls after a gateway-bindable boot load, so non-bundled plugins no longer re-run `register()` during the same boot path. Fixes #69250. Thanks @markthebest12.

extensions/slack/src/channel.test.ts

@@ -456,6 +456,127 @@ describe("slackPlugin outbound", () => {
     expect(result).toEqual({ channel: "slack", messageId: "m-media" });
   });
 
+  it("falls back to threadId when replyToId is not a Slack thread timestamp", async () => {
+    const sendSlack = vi.fn().mockResolvedValue({ messageId: "m-text" });
+    const sendText = requireSlackSendText();
+
+    const result = await sendText({
+      cfg,
+      to: "C123",
+      text: "hello",
+      accountId: "default",
+      replyToId: "msg-internal-1",
+      threadId: "1712345678.123456",
+      deps: { sendSlack },
+    });
+
+    expect(sendSlack).toHaveBeenCalledWith(
+      "C123",
+      "hello",
+      expect.objectContaining({
+        threadTs: "1712345678.123456",
+      }),
+    );
+    expect(result).toEqual({ channel: "slack", messageId: "m-text" });
+  });
+
+  it("does not stringify numeric Slack thread ids", async () => {
+    const sendSlack = vi.fn().mockResolvedValue({ messageId: "m-text" });
+    const sendText = requireSlackSendText();
+
+    await sendText({
+      cfg,
+      to: "C123",
+      text: "hello",
+      accountId: "default",
+      threadId: 1712345678.123456,
+      deps: { sendSlack },
+    });
+
+    expect(sendSlack).toHaveBeenCalledWith(
+      "C123",
+      "hello",
+      expect.objectContaining({
+        threadTs: undefined,
+      }),
+    );
+  });
+
+  it("falls back to auto-thread lookup when replyToId is not a Slack thread timestamp", () => {
+    const resolveAutoThreadId = slackPlugin.threading?.resolveAutoThreadId;
+    if (!resolveAutoThreadId) {
+      throw new Error("slack threading.resolveAutoThreadId unavailable");
+    }
+
+    const threadId = resolveAutoThreadId({
+      cfg,
+      to: "channel:C123",
+      replyToId: "msg-internal-1",
+      toolContext: {
+        currentChannelId: "C123",
+        currentThreadTs: "1712345678.123456",
+        replyToMode: "all",
+      },
+    });
+
+    expect(threadId).toBe("1712345678.123456");
+  });
+
+  it("does not recover invalid Slack auto-thread anchors", () => {
+    const resolveAutoThreadId = slackPlugin.threading?.resolveAutoThreadId;
+    if (!resolveAutoThreadId) {
+      throw new Error("slack threading.resolveAutoThreadId unavailable");
+    }
+
+    const threadId = resolveAutoThreadId({
+      cfg,
+      to: "channel:C123",
+      replyToId: "msg-internal-1",
+      toolContext: {
+        currentChannelId: "C123",
+        currentThreadTs: "thread-root",
+        replyToMode: "all",
+      },
+    });
+
+    expect(threadId).toBeUndefined();
+  });
+
+  it("does not stringify numeric thread ids in tool context", () => {
+    const buildToolContext = slackPlugin.threading?.buildToolContext;
+    if (!buildToolContext) {
+      throw new Error("slack threading.buildToolContext unavailable");
+    }
+
+    const context = buildToolContext({
+      cfg,
+      context: {
+        To: "channel:C123",
+        MessageThreadId: 1712345678.123456,
+      },
+    });
+
+    expect(context?.currentThreadTs).toBeUndefined();
+  });
+
+  it("falls back to threadId in reply transport when replyToId is not a Slack thread timestamp", () => {
+    const resolveReplyTransport = slackPlugin.threading?.resolveReplyTransport;
+    if (!resolveReplyTransport) {
+      throw new Error("slack threading.resolveReplyTransport unavailable");
+    }
+
+    expect(
+      resolveReplyTransport({
+        cfg,
+        replyToId: "msg-internal-1",
+        threadId: "1712345678.123456",
+      }),
+    ).toEqual({
+      replyToId: "1712345678.123456",
+      threadId: null,
+    });
+  });
+
   it("forwards mediaLocalRoots for sendMedia", async () => {
     const sendSlack = vi.fn().mockResolvedValue({ messageId: "m-media-local" });
     const sendMedia = requireSlackSendMedia();

extensions/slack/src/channel.ts

@@ -61,6 +61,7 @@ import {
   slackConfigAdapter,
 } from "./shared.js";
 import { parseSlackTarget } from "./target-parsing.js";
+import { normalizeSlackThreadTsCandidate, resolveSlackThreadTsValue } from "./thread-ts.js";
 import { buildSlackThreadingToolContext } from "./threading-tool-context.js";
 
 // Lazy SDK loaders. The dynamic import is hidden behind a string-literal
@@ -218,7 +219,7 @@ async function resolveSlackSendContext(params: {
   const token = getTokenForOperation(account, "write");
   const botToken = account.botToken?.trim();
   const tokenOverride = token && token !== botToken ? token : undefined;
-  const threadTsValue = params.replyToId ?? params.threadId;
+  const threadTsValue = resolveSlackThreadTsValue(params);
   return { send, threadTsValue, tokenOverride };
 }
 
@@ -608,14 +609,16 @@ export const slackPlugin: ChannelPlugin<ResolvedSlackAccount, SlackProbe> = crea
     allowExplicitReplyTagsWhenOff: false,
     buildToolContext: (params) => buildSlackThreadingToolContext(params),
     resolveAutoThreadId: ({ to, toolContext, replyToId }) =>
-      replyToId
+      normalizeSlackThreadTsCandidate(replyToId)
         ? undefined
-        : resolveSlackAutoThreadId({
+        : normalizeSlackThreadTsCandidate(
-            to,
+            resolveSlackAutoThreadId({
-            toolContext,
+              to,
-          }),
+              toolContext,
+            }),
+          ),
     resolveReplyTransport: ({ threadId, replyToId }) => ({
-      replyToId: replyToId ?? (threadId != null && threadId !== "" ? String(threadId) : undefined),
+      replyToId: resolveSlackThreadTsValue({ replyToId, threadId }),
       threadId: null,
     }),
   },
@@ -632,7 +635,7 @@ export const slackPlugin: ChannelPlugin<ResolvedSlackAccount, SlackProbe> = crea
           payload,
         }),
       sendPayload: async (ctx) => {
-        const { send, tokenOverride } = await resolveSlackSendContext({
+        const { send, threadTsValue, tokenOverride } = await resolveSlackSendContext({
           cfg: ctx.cfg,
           accountId: ctx.accountId ?? undefined,
           deps: ctx.deps,
@@ -642,6 +645,8 @@ export const slackPlugin: ChannelPlugin<ResolvedSlackAccount, SlackProbe> = crea
         const { slackOutbound } = await loadSlackOutboundAdapterModule();
         return await slackOutbound.sendPayload!({
           ...ctx,
+          replyToId: threadTsValue,
+          threadId: null,
           deps: {
             ...ctx.deps,
             slack: async (
@@ -669,7 +674,7 @@ export const slackPlugin: ChannelPlugin<ResolvedSlackAccount, SlackProbe> = crea
         });
         return await send(to, text, {
           cfg,
-          threadTs: threadTsValue != null ? String(threadTsValue) : undefined,
+          threadTs: threadTsValue,
           accountId: accountId ?? undefined,
           ...(tokenOverride ? { token: tokenOverride } : {}),
         });
@@ -696,7 +701,7 @@ export const slackPlugin: ChannelPlugin<ResolvedSlackAccount, SlackProbe> = crea
           cfg,
           mediaUrl,
           mediaLocalRoots,
-          threadTs: threadTsValue != null ? String(threadTsValue) : undefined,
+          threadTs: threadTsValue,
           accountId: accountId ?? undefined,
           ...(tokenOverride ? { token: tokenOverride } : {}),
         });

extensions/slack/src/monitor.test-helpers.ts

@@ -265,6 +265,9 @@ vi.mock("@slack/bolt", () => {
     command() {
       /* no-op */
     }
+    use() {
+      /* no-op */
+    }
     start = vi.fn().mockResolvedValue(undefined);
     stop = vi.fn().mockResolvedValue(undefined);
   }

extensions/slack/src/outbound-adapter.test.ts

@@ -115,4 +115,62 @@ describe("slackOutbound", () => {
     );
     expect(result).toEqual({ channel: "slack", messageId: "m-blocks" });
   });
+
+  it("falls back to threadId when payload replyToId is not a Slack thread timestamp", async () => {
+    sendMessageSlackMock.mockResolvedValueOnce({ messageId: "m-blocks" });
+
+    await slackOutbound.sendPayload!({
+      cfg,
+      to: "C123",
+      text: "",
+      replyToId: "msg-internal-1",
+      threadId: "1712345678.123456",
+      payload: {
+        text: "fallback text",
+        channelData: {
+          slack: {
+            blocks: [{ type: "divider" }],
+          },
+        },
+      },
+      accountId: "default",
+    });
+
+    expect(sendMessageSlackMock).toHaveBeenCalledWith(
+      "C123",
+      "fallback text",
+      expect.objectContaining({
+        threadTs: "1712345678.123456",
+      }),
+    );
+  });
+
+  it("does not thread payloads without a valid Slack thread timestamp", async () => {
+    sendMessageSlackMock.mockResolvedValueOnce({ messageId: "m-blocks" });
+
+    await slackOutbound.sendPayload!({
+      cfg,
+      to: "C123",
+      text: "",
+      replyToId: "msg-internal-1",
+      threadId: "thread-root",
+      payload: {
+        text: "fallback text",
+        channelData: {
+          slack: {
+            blocks: [{ type: "divider" }],
+          },
+        },
+      },
+      accountId: "default",
+    });
+
+    expect(sendMessageSlackMock).toHaveBeenCalledWith(
+      "C123",
+      "fallback text",
+      expect.objectContaining({
+        threadTs: undefined,
+      }),
+    );
+  });
 });

extensions/slack/src/outbound-adapter.ts

@@ -27,6 +27,7 @@ import {
 import { compileSlackInteractiveReplies } from "./interactive-replies.js";
 import { SLACK_TEXT_LIMIT } from "./limits.js";
 import type { SlackSendIdentity } from "./send.js";
+import { resolveSlackThreadTsValue } from "./thread-ts.js";
 
 const SLACK_MAX_BLOCKS = 50;
 type SlackSendFn = typeof import("./send.runtime.js").sendMessageSlack;
@@ -84,9 +85,13 @@ async function sendSlackOutboundMessage(params: {
     resolveOutboundSendDep<SlackSendFn>(params.deps, "slack") ??
     (await loadSlackSendRuntime()).sendMessageSlack;
   const slackIdentity = resolveSlackSendIdentity(params.identity);
+  const threadTs = resolveSlackThreadTsValue({
+    replyToId: params.replyToId,
+    threadId: params.threadId,
+  });
   const result = await send(params.to, params.text, {
     cfg: params.cfg,
-    threadTs: params.replyToId ?? (params.threadId != null ? String(params.threadId) : undefined),
+    threadTs,
     accountId: params.accountId ?? undefined,
     ...(params.mediaUrl
       ? {

extensions/slack/src/thread-ts.test.ts

@@ -0,0 +1,34 @@
+import { describe, expect, it } from "vitest";
+import { normalizeSlackThreadTsCandidate, resolveSlackThreadTsValue } from "./thread-ts.js";
+
+describe("Slack thread_ts resolution", () => {
+  it("accepts trimmed Slack timestamp strings", () => {
+    expect(normalizeSlackThreadTsCandidate(" 1712345678.123456 ")).toBe("1712345678.123456");
+  });
+
+  it("rejects internal reply ids", () => {
+    expect(normalizeSlackThreadTsCandidate("msg-internal-1")).toBeUndefined();
+  });
+
+  it("rejects numeric thread ids instead of stringifying them", () => {
+    expect(normalizeSlackThreadTsCandidate(1712345678.123456)).toBeUndefined();
+  });
+
+  it("falls back from invalid replyToId to valid threadId", () => {
+    expect(
+      resolveSlackThreadTsValue({
+        replyToId: "msg-internal-1",
+        threadId: "1712345678.123456",
+      }),
+    ).toBe("1712345678.123456");
+  });
+
+  it("validates fallback threadId before using it", () => {
+    expect(
+      resolveSlackThreadTsValue({
+        replyToId: "msg-internal-1",
+        threadId: "thread-root",
+      }),
+    ).toBeUndefined();
+  });
+});

extensions/slack/src/thread-ts.ts

@@ -0,0 +1,23 @@
+import { normalizeOptionalString } from "openclaw/plugin-sdk/text-runtime";
+
+const SLACK_THREAD_TS_PATTERN = /^\d+\.\d+$/;
+
+export function normalizeSlackThreadTsCandidate(
+  value?: string | number | null,
+): string | undefined {
+  if (typeof value !== "string") {
+    return undefined;
+  }
+  const normalized = normalizeOptionalString(value);
+  return normalized && SLACK_THREAD_TS_PATTERN.test(normalized) ? normalized : undefined;
+}
+
+export function resolveSlackThreadTsValue(params: {
+  replyToId?: string | number | null;
+  threadId?: string | number | null;
+}): string | undefined {
+  return (
+    normalizeSlackThreadTsCandidate(params.replyToId) ??
+    normalizeSlackThreadTsCandidate(params.threadId)
+  );
+}

extensions/slack/src/threading-tool-context.ts

@@ -5,6 +5,7 @@ import type {
 import type { OpenClawConfig } from "openclaw/plugin-sdk/config-runtime";
 import { normalizeOptionalString } from "openclaw/plugin-sdk/text-runtime";
 import { resolveSlackAccount, resolveSlackReplyToMode } from "./accounts.js";
+import { normalizeSlackThreadTsCandidate } from "./thread-ts.js";
 
 export function buildSlackThreadingToolContext(params: {
   cfg: OpenClawConfig;
@@ -28,7 +29,7 @@ export function buildSlackThreadingToolContext(params: {
     : normalizeOptionalString(params.context.NativeChannelId);
   return {
     currentChannelId,
-    currentThreadTs: threadId != null ? String(threadId) : undefined,
+    currentThreadTs: normalizeSlackThreadTsCandidate(threadId),
     replyToMode: effectiveReplyToMode,
     hasRepliedRef: params.hasRepliedRef,
   };

src/auto-reply/reply/route-reply.test.ts

@@ -61,11 +61,19 @@ const slackMessaging: ChannelMessagingAdapter = {
 
 const slackThreading: ChannelThreadingAdapter = {
   resolveReplyTransport: ({ threadId, replyToId }) => ({
-    replyToId: replyToId ?? (threadId != null && threadId !== "" ? String(threadId) : undefined),
+    replyToId: resolveSlackThreadTsCandidate(replyToId) ?? resolveSlackThreadTsCandidate(threadId),
     threadId: null,
   }),
 };
 
+function resolveSlackThreadTsCandidate(value?: string | number | null): string | undefined {
+  if (typeof value !== "string") {
+    return undefined;
+  }
+  const normalized = value.trim();
+  return /^\d+\.\d+$/.test(normalized) ? normalized : undefined;
+}
+
 const mattermostThreading: ChannelThreadingAdapter = {
   resolveReplyTransport: ({ threadId, replyToId }) => ({
     replyToId: replyToId ?? (threadId != null && threadId !== "" ? String(threadId) : undefined),
@@ -489,6 +497,21 @@ describe("routeReply", () => {
     });
   });
 
+  it("uses Slack threadId when routed replyToId is an internal message id", async () => {
+    await routeReply({
+      payload: { text: "hi", replyToId: "msg-internal-1" },
+      channel: "slack",
+      to: "channel:C123",
+      threadId: "1710000000.9999",
+      cfg: {} as never,
+    });
+    expectLastDelivery({
+      channel: "slack",
+      replyToId: "1710000000.9999",
+      threadId: null,
+    });
+  });
+
   it("uses threadId as replyToId for Mattermost when replyToId is missing", async () => {
     await routeReply({
       payload: { text: "hi" },