Use files_upload_v2 API to upload media attachments in Slack messages.
This enables the message tool's media parameter to work correctly
when sending images or other files through the Slack channel.
Requires files:write OAuth scope.
Slack has no native table support, so Markdown tables are passed
through verbatim by slackify-markdown. Pre-process tables into
readable key-value rows before converting to mrkdwn.
Assisted-by: Claude 4.6 Opus (Anthropic)
Replace the regex-based Markdown-to-Slack converter with the
slackify-markdown library, which uses a proper Markdown parser
(markdown-it-py, already a dependency) to correctly handle headings,
bold/italic, code blocks, links, bullet lists, and strikethrough.
The regex approach didn't handle headings (###), bullet lists (* ),
or code block protection, causing raw Markdown to leak into Slack
messages.
Net -40 lines.
Assisted-by: Claude 4.6 Opus (Anthropic)
