Start a thread Run in API Explorer
Opens a new conversation in the newsletter's community and returns it.
Needs content: write.
The thread is written by the person the credential belongs to, the
same person createArticle credits, and readers see it exactly as if
they had posted it in Commune. Subscribers are notified the way they
are for any new thread, and an @username in the text mentions that
person.
content is Markdown, as readers write it in Commune: plain text with
light formatting, up to 5,000 characters. It is stored as sent. It can
be left out when media attaches something, so a photo with no
caption is a thread; a body with neither answers 400.
visibility decides where the thread can be read. subscribers, the
default, keeps it inside the newsletter. public also puts it on
Commune's global feed in the same write, which is what
Put a thread on the global feed (POST /threads/{thread}/publish) does
to a thread that already exists.
Publishes thread.created, and thread.published with source
created_public when the thread is created public.
Headers
-
A value of your choosing naming the change this request is making.
Send the same value again to retry the same request. Commune replays the answer the first attempt gave instead of making the change twice, and marks the replay with an
Idempotent-Replay: trueresponse header. Send a different value for a different change: a key reused for a request that differs in any way answers409, because replaying an answer to a question you did not ask is a wrong answer you could not detect.A UUID per change is the usual choice. Remembered for 24 hours, per credential, so two credentials choosing the same value never see each other's answers.
Required, not optional.
Minimum length is
1, maximum length is255. -
The contract version this request is written against. Every version published so far is a release date (
YYYY-MM-DD), which is why the examples look like one, but the value is an opaque identifier: match it against the versions this API publishes rather than parsing it, because a future one may not be only a date. An unknown value answers400withinvalid_version.Omitting the header pins the request to the version that was current when the API key was issued, so an integration keeps working when a newer version ships.
Minimum length is
1.
Responses
-
The thread, as created. It has no replies yet.
-
The request was malformed, and the same request will fail the same way until it is changed.
paramnames the parameter or header at fault when there is exactly one, andallowed_valueslists what it accepts when that is a finite set. The code isbad_requestfor every case below except the last.- A query parameter: one the operation does not have, a value
outside its set, range or format (an unparseable cursor, an unknown
expandpath orfieldsname, an identifier that is not a UUID), or a required one left out, such asqon a search ornewsletterwhen the credential reaches more than one. - The request body: not JSON, not the shape the operation reads,
a property it does not write, or a value of the wrong type, length
or format.
paramis absent here, since the body is not a parameter, and the message names the property. - The
Idempotency-Keyheader, on an operation that changes something: missing, or a value this API will not store. - An unrecognised
Commune-Version, which answers with its own code,invalid_version, because it is never fixed by changing the body.
- A query parameter: one the operation does not have, a value
outside its set, range or format (an unparseable cursor, an unknown
-
No credential was presented, or it is malformed, unknown, revoked or expired, or it is an access token minted for a different audience.
Every one of these answers identically, down to the wording and the headers, so a refusal never confirms that a string was once real.
-
The credential is allowed to do this but the newsletter's plan does not include it.
Two surfaces can answer it: insights, the engagement and metrics operations, which are the only reads Commune reserves the right to meter, and writing, every operation that changes something.
Every other read stays free on every plan, so a credential refused at one of these can still read everything else. The body names the plan the newsletter is on and the plans that would work.
This status is predictable and should not be how you discover it.
GET /newsletters/{newsletter}/entitlementsanswers the same question in advance, carrying the same plan list this puts inallowed_valuesand the same sentence it puts inmessage. Read it once at the start of a run rather than finding out in the middle of one. -
The credential is valid but is not allowed to do this. Two codes answer with this status, and
error.codesays which.insufficient_scope: it does not hold the permission. The operation needs, say,audience: readon the newsletter addressed, and this credential holds less than that there.allowed_valuescarries the permission that was needed, and the message says what the credential does hold on that newsletter, because a credential granted the wrong family and a credential belonging to somebody whose standing on the team has narrowed look identical without it. The answer can differ per newsletter: the same credential may be allowed here and refused on the next one it reaches.The same code answers an operation that needs the account permission from a credential that does not carry it. That permission is about the person a credential belongs to rather than about any newsletter, so nothing granted on a newsletter adds up to it. It is granted on the credential itself, when a key is minted or when an authorization asks for
account:read.And it answers a parameter the credential may send, but not with the value it sent: a filter a credential holding only
readpermissions may not use, or anexpandpath whose rows need a permission the operation does not.paramnames the parameter, andallowed_valuescarries what this credential may send instead, or is absent when it may send nothing there at all.forbidden: it may not act here at all. Either the credential does not reach the newsletter addressed, because it was never granted it or because the person it belongs to can no longer act on it, or it reaches no newsletter at all;paramisnewsletter, andGET /newsletterslists the ones it does reach. Or, onDELETE /api-keys/{key}, the credential named belongs to somebody else. Neither carriesallowed_values, because there is no value to send instead. -
No such resource, or the key is not allowed to know that it exists. Commune answers
404rather than403where distinguishing the two would leak the existence of private content. -
The request collided with something. On a write this is always the
Idempotency-Key, in one of two ways, and the message says which.Either the key was already used for a different request, which is refused rather than answered with the earlier request's result. Or an earlier request using the same key has not finished, or never reported an outcome, in which case this one was not run and the key becomes usable again shortly.
Nothing was changed by a request that answers this.
-
The request is well formed and every value in it is legal, and the state of what it addresses refuses it anyway. The message says what about that state is in the way.
-
Too many requests. Back off and retry after the interval named by the
Retry-Afterresponse header.One of the budgets in
RateLimit-Policyran out, and theRateLimit-*headers on this response say which and when it resets. -
Something failed inside Commune. The request may be retried.
curl \
--request POST 'https://api.usecommune.com/newsletters/9a4c1c6e-0f2b-4f47-9d3f-6d1b1a2c3d4e/threads' \
--header "Authorization: Bearer $ACCESS_TOKEN" \
--header "Content-Type: application/json" \
--header "Idempotency-Key: 3f7c1a26-9b0e-4f5a-9a2c-2c8f1d6b4e77" \
--header "Commune-Version: 2026-08-26" \
--data '{
"content": "What should the next issue dig into? Reply with one topic."
}'
{
"content": "What should the next issue dig into? Reply with one topic."
}
{
"object": "thread",
"id": "string",
"short_id": "string",
"newsletter": {
"object": "newsletter",
"id": "9a4c1c6e-0f2b-4f47-9d3f-6d1b1a2c3d4e"
},
"author": {
"object": "newsletter",
"id": "9a4c1c6e-0f2b-4f47-9d3f-6d1b1a2c3d4e"
},
"content": "string",
"media": [
{
"url": "https://example.com",
"type": "string",
"thumbnail": "https://example.com"
}
],
"visibility": "public",
"is_article_thread": true,
"article": {
"object": "newsletter",
"id": "9a4c1c6e-0f2b-4f47-9d3f-6d1b1a2c3d4e"
},
"reply_count": 42,
"view_count": 42,
"created_at": "2026-05-04T09:42:00Z",
"updated_at": "2026-05-04T09:42:00Z",
"edited_at": "2026-05-04T09:42:00Z",
"last_activity_at": "2026-05-04T09:42:00Z"
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
# Headers
WWW-Authenticate: string
# Payload
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
# Headers
Retry-After: 42
# Payload
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
# Headers
Retry-After: 42
# Payload
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}
{
"error": {
"code": "bad_request",
"message": "Newsletter not found.",
"param": "cursor",
"allowed_values": [
"subscribed",
"unsubscribed",
"bounced",
"complained",
"pending"
],
"request_id": "req_01j9c8h1q7m3n4p5r6s7t8u9v0",
"docs_url": "https://usecommune.dev/errors/not_found"
}
}