The Fedify object dispatcher constructs the post lookup URL from the
{+id} path variable (e.g. "replies/bd78a"), which has no trailing slash.
Posts in MongoDB store their URL with a trailing slash, so the exact
findOne() match was silently returning null → Fedify serving 404 →
mountains.social showing "Could not connect to the given address".
Fix uses $in to try both variants so the dispatcher works regardless
of whether the request URL has a trailing slash or not.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
02919b6e37