A first comment is posted from the author's own account immediately after a target publishes —
the "link in the comments" pattern that keeps a URL out of the caption where it would suppress
reach.firstComment is per target, because the same link deserves different wording on LinkedIn
than on Instagram.
Support and limits
Platform
Supported
Comment limit
Instagram
yes
2,200 chars
Threads
yes (a reply to the post)
500 chars
LinkedIn
yes
1,250 chars
X
**no** — reports `unsupported`
—
Exceeding a platform's comment limit fails the comment with a message naming the actual length
and the allowed one. The post itself still publishes.
The comment never fails the post
Publish first, comment second
By the time the comment is attempted the post is already live. A comment failure is therefore reported alongside the post rather than turning a successful publish into a failure.
Read the outcome on the target:
`commentStatus`
Meaning
`none`
No `firstComment` was sent
`published`
The comment posted; `commentId` holds the platform's id
`failed`
The platform refused it; `commentError` says why
`unsupported`
The platform cannot post comments (X)
Permission failures name their own fix
Platforms answer a missing permission with copy like "Application does not have permission for
this action", which never says whose permission is missing. Chirio appends the actual remedy,
and it differs:
Instagram — reconnect the account; the connection predates comment permission and only a
fresh authorisation can grant it.
Threads — reconnect the profile; same story with reply permission.
LinkedIn — reconnecting will not help. It is an authorisation Chirio holds with
LinkedIn, not one your user can grant. Publishing keeps working meanwhile; contact support.
Billing
A first comment is a second network write on the same target, billed only if the platform
accepted it. A comment reported failed or unsupported costs nothing.
The pattern does not work on X
X has no comment API, so a link cannot be moved out of the caption there — and an X post containing a link is priced at roughly 13× one without. See the X page.
{
"content": "We rebuilt publishing from scratch. Here is what changed.",
"platforms": [
{
"platform": "linkedin",
"accountId": "77bb...",
"firstComment": "Full write-up: https://example.com/rebuild"
},
{
"platform": "instagram",
"accountId": "8f2c...",
"firstComment": "Link in bio 👆"
}
]
}
