Facebook Messenger messages that share a post no longer break message
ingestion. Following the recent sticker change, Meta now sends a shared
post as a new `post` attachment type. Chatwoot didn't recognise `post`
as a valid attachment file type, so the webhook job crashed and the
message — and any others in the same batch — failed to sync. Shared
posts now appear in the conversation as a fallback link (title + URL),
the same way `share` attachments already do.
This is the same class of bug as #14793 (sticker), just a different
attachment type.
#### Root cause
`post` was neither skipped as unsupported nor mapped to a valid
`file_type`, so `attachment_params` produced `file_type: :post`. The
`Attachment#file_type` enum has no `post` value, so it raised
`ArgumentError: 'post' is not a valid file_type`, crashing
`Webhooks::FacebookEventsJob`.
#### Fix
The Facebook builder already maps `share -> :fallback` because shared
posts point to facebook.com page URLs rather than downloadable media. A
`post` is the same kind of attachment, so map both `share` and `post` to
`fallback` (stores the title/link, no download attempt). Also read the
fallback title from `payload.title`, since the post payload nests it
there rather than at the top level.
## How to reproduce
1. Connect a Facebook Page inbox.
2. Share a Facebook post into Messenger to that page.
3. Before this change: `Webhooks::FacebookEventsJob` raises
`ArgumentError: 'post' is not a valid file_type` and the message is
dropped.
4. After this change: the shared post shows up in the conversation as a
fallback link.
Co-authored-by: Muhsin <12408980+muhsin-k@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
