diff --git a/packages/ims/shared/synthetic-owner.test.ts b/packages/ims/shared/synthetic-owner.test.ts
index 0f8732d..ecd317d 100644
--- a/packages/ims/shared/synthetic-owner.test.ts
+++ b/packages/ims/shared/synthetic-owner.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from "bun:test";
-import { isSyntheticOwner } from "./synthetic-owner";
+import { isSyntheticOwner, threadTsField } from "./synthetic-owner";
 
 describe("isSyntheticOwner", () => {
   it("returns true for task: prefix", () => {
@@ -30,3 +30,35 @@ describe("isSyntheticOwner", () => {
     expect(isSyntheticOwner("user-cron-job:x")).toBe(false);
   });
 });
+
+describe("threadTsField", () => {
+  it("preserves a real Slack message timestamp", () => {
+    expect(threadTsField("1717000000.000200")).toEqual({
+      thread_ts: "1717000000.000200",
+    });
+  });
+
+  it("omits thread_ts for a cron-job placeholder (ODE-DEAMON-7)", () => {
+    const field = threadTsField(
+      "cron-job:a86fbdc5-01df-4caf-9e0c-c0c199f00379:1781391600000"
+    );
+    expect(field).toEqual({});
+    expect(field).not.toHaveProperty("thread_ts");
+  });
+
+  it("omits thread_ts for task: and legacy cron: placeholders", () => {
+    expect(threadTsField("task:abc123")).toEqual({});
+    expect(threadTsField("cron:daily")).toEqual({});
+  });
+
+  it("omits thread_ts for missing/empty thread ids", () => {
+    expect(threadTsField(undefined)).toEqual({});
+    expect(threadTsField(null)).toEqual({});
+    expect(threadTsField("")).toEqual({});
+  });
+
+  it("spreads into a payload without leaving an undefined key", () => {
+    const payload = { channel: "C1", ...threadTsField("task:abc") };
+    expect(Object.keys(payload)).toEqual(["channel"]);
+  });
+});
diff --git a/packages/ims/shared/synthetic-owner.ts b/packages/ims/shared/synthetic-owner.ts
index 616b414..5766900 100644
--- a/packages/ims/shared/synthetic-owner.ts
+++ b/packages/ims/shared/synthetic-owner.ts
@@ -17,3 +17,23 @@ export function isSyntheticOwner(userId: string | null | undefined): boolean {
   if (!userId) return false;
   return SYNTHETIC_OWNER_PREFIXES.some((prefix) => userId.startsWith(prefix));
 }
+
+/**
+ * Build the `thread_ts` field for a Slack API payload, omitting it entirely
+ * when `threadId` is a synthetic placeholder.
+ *
+ * The task/cron schedulers address a run by a synthetic thread id
+ * (`task:{id}` / `cron-job:{id}:{run}`) before Slack has assigned a real
+ * `thread_ts`. Slack rejects those strings with `invalid_thread_ts` because
+ * they are not message timestamps, so the message is dropped and reported as
+ * a delivery failure. Omitting the field degrades to a top-level channel
+ * post, which keeps the message visible.
+ *
+ * Spread the result into the payload: `{ channel, ...threadTsField(id) }`.
+ */
+export function threadTsField(
+  threadId: string | null | undefined
+): { thread_ts?: string } {
+  if (!threadId || isSyntheticOwner(threadId)) return {};
+  return { thread_ts: threadId };
+}
diff --git a/packages/ims/slack/api.ts b/packages/ims/slack/api.ts
index d61f34d..bad1012 100644
--- a/packages/ims/slack/api.ts
+++ b/packages/ims/slack/api.ts
@@ -5,6 +5,7 @@ import {
   type ThreadMessage,
 } from "@/ims/shared/thread-messages";
 import type { AttachmentSource } from "@/ims/shared/attachment-store";
+import { threadTsField } from "@/ims/shared/synthetic-owner";
 import { getApp, getSlackBotToken } from "./client";
 
 // ---------------------------------------------------------------------------
@@ -123,7 +124,11 @@ async function slackFileUpload(
   return slackApiCall("files.completeUploadExternal", {
     files: [{ id: uploadInfo.file_id, title: args.title || args.filename }],
     channel_id: args.channelId,
-    thread_ts: args.threadId,
+    // Synthetic placeholder thread ids (`task:` / `cron-job:` / `cron:`) are
+    // not valid Slack timestamps. `ode send file` invoked from a scheduled
+    // task/cron run before a real thread exists would otherwise fail with
+    // `invalid_thread_ts`; upload to the channel top level instead.
+    ...(threadTsField(args.threadId)),
     initial_comment: args.initialComment,
   }, args.token);
 }
diff --git a/packages/ims/slack/client.ts b/packages/ims/slack/client.ts
index ffc85bd..52f4d65 100644
--- a/packages/ims/slack/client.ts
+++ b/packages/ims/slack/client.ts
@@ -29,7 +29,7 @@ import { createProcessorManager } from "@/ims/shared/processor-manager";
 import { SlackAuthRegistry, type WorkspaceAuth } from "@/ims/slack/state/auth-registry";
 import { SlackMessageUpdateManager } from "@/ims/slack/message-update-manager";
 import { deliveryStats, isRateLimitError } from "@/ims/shared/delivery-stats";
-import { isSyntheticOwner } from "@/ims/shared/synthetic-owner";
+import { isSyntheticOwner, threadTsField } from "@/ims/shared/synthetic-owner";
 
 export interface MessageContext {
   channelId: string;
@@ -309,7 +309,28 @@ export async function sendMessage(
   const formattedText = markdownToSlack(text);
   const chunks = splitForSlack(formattedText);
   const workspace = slackAuthRegistry.getChannelWorkspaceName(rawChannelId) || "unknown";
-  const botToken = getSlackBotTokenForProcessor(processorId) ?? getSlackBotToken(channelId, threadId);
+
+  // A "synthetic" thread id (`task:{id}` / `cron-job:{id}:{run}` / `cron:{id}`)
+  // is an internal placeholder the task/cron schedulers use before a real
+  // Slack `thread_ts` exists. Slack rejects these with `invalid_thread_ts`
+  // because they are not message timestamps, so any intermediate output the
+  // agent runtime emits during a scheduled run is lost and captured as a
+  // Sentry delivery failure (ODE-DEAMON-7). Degenerate to a top-level channel
+  // post instead so the message still lands in the channel.
+  const threadIsSynthetic = isSyntheticOwner(threadId);
+
+  // Token resolution. For real threads prefer the registry-bound token for
+  // this (channel, thread) — that's the token the inbound router observed
+  // delivering the parent message. For synthetic placeholders the call has
+  // degenerated to a top-level post and the registry has no entry for a fake
+  // `thread_ts`, so resolve via the channel's workspace first (mirroring
+  // `sendChannelMessage`) to avoid the multi-workspace case where
+  // `getSlackBotToken` returns the first registered token instead of the one
+  // for `rawChannelId`.
+  const botToken = getSlackBotTokenForProcessor(processorId)
+    ?? (threadIsSynthetic
+      ? (getWorkspaceBotTokenForChannel(channelId) ?? getSlackBotToken(channelId))
+      : getSlackBotToken(channelId, threadId));
 
   if (!botToken) {
     log.warn("No Slack bot token available for channel", { channelId });
@@ -320,6 +341,7 @@ export async function sendMessage(
       workspace,
       channel: channelId,
       thread: threadId,
+      threadIsSynthetic,
       botTokenLast6: tokenLast6(botToken),
       text,
       chunks: chunks.length,
@@ -329,6 +351,7 @@ export async function sendMessage(
       workspace,
       channel: channelId,
       thread: threadId,
+      threadIsSynthetic,
       botTokenLast6: tokenLast6(botToken),
       text,
       chunks: chunks.length,
@@ -346,7 +369,7 @@ export async function sendMessage(
     try {
       const result = await slackApp.client.chat.postMessage({
         channel: rawChannelId,
-        thread_ts: threadId,
+        ...(threadTsField(threadId)),
         text: chunk,
         token: botToken,
       });
@@ -358,7 +381,12 @@ export async function sendMessage(
       });
       lastTs = result.ts;
       if (botToken && result.ts) {
-        slackAuthRegistry.setThreadBotToken(rawChannelId, threadId, botToken);
+        // Never bind a real bot token to a synthetic placeholder thread id —
+        // the real platform-assigned thread is `result.ts` for the first
+        // message of the run, which `setMessageBotToken` covers below.
+        if (!threadIsSynthetic) {
+          slackAuthRegistry.setThreadBotToken(rawChannelId, threadId, botToken);
+        }
         slackAuthRegistry.setMessageBotToken(rawChannelId, result.ts, botToken);
       }
     } catch (err) {