PR #17348: fix(send_message): native Slack media uploads for cross-channel/DM sends (#17261)

• Repository: NousResearch/hermes-agent
• Author: briandevans
• State: open | merged: False
• Link: https://github.com/NousResearch/hermes-agent/pull/17348

Description (problem / solution / changelog)

Summary

• Cross-channel send_message to Slack drops MEDIA attachments and emits "MEDIA attachments were omitted for slack…" even though SlackAdapter has full media support via files_upload_v2. This PR adds the missing media branch.
• _send_slack now uploads files through slack_sdk.web.async_client.AsyncWebClient.files_upload_v2 when media_files is non-empty, with thread_ts forwarded for in-thread cross-channel sends.
• The "supported platforms" warning + media-only-no-text error now list slack.

Fixes #17261.

The bug

Reporter (#17261) traced it: BasePlatformAdapter._process_message_background (in-thread agent replies) dispatches MEDIA tags through the SlackAdapter's send_image_file / send_voice / send_video / send_document (all call files_upload_v2). The send_message tool — used for cross-channel and DM sends — has its own hand-rolled per-platform helpers in tools/send_message_tool.py and just lacked a Slack-with-media branch:

• _send_to_platform had if platform == Platform.TELEGRAM / DISCORD / MATRIX and media_files / SIGNAL and media_files branches that pass media_files through to platform-specific helpers.
• Slack fell through to the generic "non-media platforms" block (tools/send_message_tool.py:580), which surfaced the warning at tools/send_message_tool.py:589-593 and called _send_slack(token, chat_id, chunk) — text only.

So the result the user saw — "send works in thread, fails when DMing or sending to another channel" — matches the code path exactly.

The fix

Two-part surgical change in tools/send_message_tool.py:

1. _send_to_platform — add a Slack media branch (mirrors the existing Telegram / Discord branches). Media attaches to the last chunk only so we don't upload duplicates per-chunk on long messages:

   if platform == Platform.SLACK and media_files:
       last_result = None
       for i, chunk in enumerate(chunks):
           is_last = (i == len(chunks) - 1)
           result = await _send_slack(
               pconfig.token, chat_id, chunk,
               media_files=media_files if is_last else [],
               thread_id=thread_id,
           )
           ...

2. _send_slack — extend signature to (token, chat_id, message, media_files=None, thread_id=None). When media_files is empty, behavior is unchanged (still uses aiohttp + chat.postMessage). When media is present, it uses slack_sdk.web.async_client.AsyncWebClient(token=token).files_upload_v2(...) per file, with the message text carried as initial_comment on the first upload only (so multi-file sends don't duplicate the caption). thread_id becomes thread_ts so the upload lands in the right thread when one is specified.

3. The "MEDIA attachments were omitted" warning + the media-only-no-text error were updated to list slack as supported.

Approach choice: directly using AsyncWebClient(token=...) mirrors the one-shot HTTP/SDK style of the other senders in this file. Going through _send_yuanbao-style "fetch the running gateway adapter" would couple the cross-channel send to the gateway's lifecycle (vs. a clean, restartable HTTP/SDK call) and didn't seem worth the indirection — SlackAdapter._upload_file itself is just a wrapper around the same files_upload_v2 API call. The SlackAdapter is untouched.

Test plan

• Focused regression — 10 new tests across two classes:
  • TestSendSlackMedia (6): single image, thread_ts forwarding, multi-file caption-on-first-only invariant, missing-file error, SlackApiError surfacing, and a regression that the text-only path does not import slack_sdk (gates the dep behind media_files).
  • TestSendToPlatformSlackMedia (4): media branch routing, last-chunk-only attachment for chunked messages over Slack's 39000-char MAX_MESSAGE_LENGTH, text-only Slack still hits chat.postMessage, and the warning text now lists slack.
• Adjacent suite — tests/tools/test_send_message_tool.py (97/97 pass, all preexisting Slack tests still green) and tests/gateway/test_slack*.py (228/228 pass).
• Regression guard — with tools/send_message_tool.py reverted to 58a6171bf (current origin/main) but the new tests in place, three representative new tests fail (test_single_image_upload_uses_files_upload_v2, test_media_present_uses_send_slack_with_media, test_warning_message_lists_slack_as_supported); restoring the fix makes them pass.

Related

Fixes #17261.

Changed files

• tests/tools/test_send_message_tool.py (modified, +424/-0)
• tools/send_message_tool.py (modified, +119/-5)