Record an unanswered turn without overriding a newer decision
Append an unanswered-turn reply only while the observed run and record version still own an active comment. The checks and reply share a row lock. A newer decision or answer returns 409 with the current comment. Reply identity prevents duplicate writes during retries.
The reply’s client_id is validated before the run and version are
compared, so a malformed id is 422 whether or not they still match.
When the thread belongs to a work item, the run and the active state are read off the work item rather than the comment; the version stays the comment’s own and is never translated between the two registers.
curl --request POST \
--url https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '
{
"reply": {
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry."
},
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"expected_version": 4
}
'import requests
url = "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply"
payload = {
"reply": {
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry."
},
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"expected_version": 4
}
headers = {
"Authorization": "Bearer <token>",
"Content-Type": "application/json"
}
response = requests.post(url, json=payload, headers=headers)
print(response.text)const options = {
method: 'POST',
headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
body: JSON.stringify({
reply: {
client_id: 'backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
body: JSON.stringify('This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.')
},
run_id: 'run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
expected_version: 4
})
};
fetch('https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => json_encode([
'reply' => [
'client_id' => 'backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
'body' => 'This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.'
],
'run_id' => 'run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
'expected_version' => 4
]),
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>",
"Content-Type: application/json"
],
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"strings"
"net/http"
"io"
)
func main() {
url := "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply"
payload := strings.NewReader("{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}")
req, _ := http.NewRequest("POST", url, payload)
req.Header.Add("Authorization", "Bearer <token>")
req.Header.Add("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.post("https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}"
response = http.request(request)
puts response.read_body{
"preview_comment": {
"id": 31877,
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"lock_version": 5,
"client_id": "c-3f9a2e71",
"n": 4,
"body": "The hero headline wraps onto three lines on mobile. Can we tighten it so it fits on two?",
"status": "review",
"status_at_ms": 1789467150000,
"page_url": "/",
"author_name": "Michael Scott",
"created_at_ms": 1789398131000,
"template_id": 902114,
"section": {
"id": "hero-banner-1",
"type": "hero-banner"
},
"block": null,
"target": {
"tag": "h1",
"selector": "section[data-section-id=\"hero-banner-1\"] h1.hero__title",
"text": "Limitless Paper in a Paperless World",
"html": "<h1 class=\"hero__title\">Limitless Paper in a Paperless World</h1>"
},
"pin": {
"x": 48.2,
"y": 22.7,
"ox": 0.41,
"oy": 0.63
},
"mentions": [
{
"id": "52018",
"name": "Pam Beesly"
}
],
"mentioned_project": null,
"proof_baseline": {
"url": "https://cdn.fluid.app/dunder-mifflin/assets/77104/preview-before.png",
"width": 1440,
"height": 900,
"captured_at_ms": 1789464360000
},
"work_item": null,
"board_position": null,
"board_position_at_ms": null,
"assignee": {
"id": "52001",
"name": "Michael Scott",
"kind": "user"
},
"assigner": {
"id": "52001",
"name": "Michael Scott",
"kind": "user"
},
"assigned_at_ms": 1789467150000,
"priority": null,
"priority_at_ms": null,
"replies": [
{
"client_id": "r-5c20e9b4",
"run_id": null,
"body": "Agreed. Let's drop the font size a step below 768px rather than rewording it.",
"author_name": "Pam Beesly",
"created_at_ms": 1789398277000,
"mentions": [],
"shot": null,
"proof": null
},
{
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.",
"author_name": "Mist",
"created_at_ms": 1789467150000,
"mentions": [],
"shot": null,
"proof": null
}
]
},
"status": 200,
"meta": {
"request_uuid": "7c1e9a52-4b3d-4f0e-9d2a-81f6c3b5e240",
"timestamp": "2026-09-15T10:12:30Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}Authorizations
Bearer authentication header of the form Bearer <token>, where <token> is your auth token.
Path Parameters
Id of the theme that owns the comment.
Client-generated id of the root comment.
Body
Response
The current comment with the backstop recorded.
A single comment, wrapped in the standard response envelope.
curl --request POST \
--url https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '
{
"reply": {
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry."
},
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"expected_version": 4
}
'import requests
url = "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply"
payload = {
"reply": {
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry."
},
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"expected_version": 4
}
headers = {
"Authorization": "Bearer <token>",
"Content-Type": "application/json"
}
response = requests.post(url, json=payload, headers=headers)
print(response.text)const options = {
method: 'POST',
headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
body: JSON.stringify({
reply: {
client_id: 'backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
body: JSON.stringify('This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.')
},
run_id: 'run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
expected_version: 4
})
};
fetch('https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
CURLOPT_POSTFIELDS => json_encode([
'reply' => [
'client_id' => 'backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
'body' => 'This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.'
],
'run_id' => 'run_01J8Z3K4QF7M2V9XB6T0RC5HWD',
'expected_version' => 4
]),
CURLOPT_HTTPHEADER => [
"Authorization: Bearer <token>",
"Content-Type: application/json"
],
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"strings"
"net/http"
"io"
)
func main() {
url := "https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply"
payload := strings.NewReader("{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}")
req, _ := http.NewRequest("POST", url, payload)
req.Header.Add("Authorization", "Bearer <token>")
req.Header.Add("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.post("https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.fluid.app/api/v202604/themes/{theme_id}/preview_comments/{client_id}/backstop-reply")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n \"reply\": {\n \"client_id\": \"backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"body\": \"This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.\"\n },\n \"run_id\": \"run_01J8Z3K4QF7M2V9XB6T0RC5HWD\",\n \"expected_version\": 4\n}"
response = http.request(request)
puts response.read_body{
"preview_comment": {
"id": 31877,
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"lock_version": 5,
"client_id": "c-3f9a2e71",
"n": 4,
"body": "The hero headline wraps onto three lines on mobile. Can we tighten it so it fits on two?",
"status": "review",
"status_at_ms": 1789467150000,
"page_url": "/",
"author_name": "Michael Scott",
"created_at_ms": 1789398131000,
"template_id": 902114,
"section": {
"id": "hero-banner-1",
"type": "hero-banner"
},
"block": null,
"target": {
"tag": "h1",
"selector": "section[data-section-id=\"hero-banner-1\"] h1.hero__title",
"text": "Limitless Paper in a Paperless World",
"html": "<h1 class=\"hero__title\">Limitless Paper in a Paperless World</h1>"
},
"pin": {
"x": 48.2,
"y": 22.7,
"ox": 0.41,
"oy": 0.63
},
"mentions": [
{
"id": "52018",
"name": "Pam Beesly"
}
],
"mentioned_project": null,
"proof_baseline": {
"url": "https://cdn.fluid.app/dunder-mifflin/assets/77104/preview-before.png",
"width": 1440,
"height": 900,
"captured_at_ms": 1789464360000
},
"work_item": null,
"board_position": null,
"board_position_at_ms": null,
"assignee": {
"id": "52001",
"name": "Michael Scott",
"kind": "user"
},
"assigner": {
"id": "52001",
"name": "Michael Scott",
"kind": "user"
},
"assigned_at_ms": 1789467150000,
"priority": null,
"priority_at_ms": null,
"replies": [
{
"client_id": "r-5c20e9b4",
"run_id": null,
"body": "Agreed. Let's drop the font size a step below 768px rather than rewording it.",
"author_name": "Pam Beesly",
"created_at_ms": 1789398277000,
"mentions": [],
"shot": null,
"proof": null
},
{
"client_id": "backstop-run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"run_id": "run_01J8Z3K4QF7M2V9XB6T0RC5HWD",
"body": "This turn ended without posting an answer. The run stopped before it could change the hero section; send it again to retry.",
"author_name": "Mist",
"created_at_ms": 1789467150000,
"mentions": [],
"shot": null,
"proof": null
}
]
},
"status": 200,
"meta": {
"request_uuid": "7c1e9a52-4b3d-4f0e-9d2a-81f6c3b5e240",
"timestamp": "2026-09-15T10:12:30Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error": {
"message": "<string>",
"details": {}
},
"status": 123,
"meta": {
"request_uuid": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}