When replying to a Slack thread, files attached to the root message were
not being fetched. The existing `resolveSlackThreadStarter()` fetched the
root message text via `conversations.replies` but ignored the `files[]`
array in the response.
Changes:
- Add `files` to `SlackThreadStarter` type and extract from API response
- Download thread starter files when the reply message has no attachments
- Add verbose log for thread starter file hydration
Fixes issue where asking about a PDF in a thread reply would fail because
the model never received the file content from the root message.
Fixes two bugs in Slack tool notification delivery:
1. Tool notifications ignored verbose=false - normalized verbose values so
boolean false/'false' are properly treated as 'off'
2. Thread context lost - Slack outbound adapter now falls back to threadId
when replyToId is missing, and MessageThreadId is set for thread replies
Closes#1333
The `channels.slack.requireMention` setting was defined in the schema
but never passed to `resolveSlackChannelConfig()`, which always
defaulted to `true`. This meant setting `requireMention: false` at the
top level had no effect—channels still required mentions.
Pass `slackCfg.requireMention` as `defaultRequireMention` to the
resolver and use it as the fallback instead of hardcoded `true`.
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
