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POST
/
public-api
/
chat
/
sessions
/
{session_id}
/
messages
Append a user message + enqueue a chat turn
curl --request POST \
  --url https://api.neoagent.io/public-api/chat/sessions/{session_id}/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "attachments": [
    {
      "blob_path": "<string>",
      "mime": "<string>",
      "alt": "<string>",
      "filename": "<string>"
    }
  ],
  "client_message_id": "<string>",
  "message": "",
  "model_tier": "FAST"
}
'
import requests

url = "https://api.neoagent.io/public-api/chat/sessions/{session_id}/messages"

payload = {
    "attachments": [
        {
            "blob_path": "<string>",
            "mime": "<string>",
            "alt": "<string>",
            "filename": "<string>"
        }
    ],
    "client_message_id": "<string>",
    "message": "",
    "model_tier": "FAST"
}
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({
    attachments: [
      {blob_path: '<string>', mime: '<string>', alt: '<string>', filename: '<string>'}
    ],
    client_message_id: '<string>',
    message: '',
    model_tier: 'FAST'
  })
};

fetch('https://api.neoagent.io/public-api/chat/sessions/{session_id}/messages', 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.neoagent.io/public-api/chat/sessions/{session_id}/messages",
  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([
    'attachments' => [
        [
                'blob_path' => '<string>',
                'mime' => '<string>',
                'alt' => '<string>',
                'filename' => '<string>'
        ]
    ],
    'client_message_id' => '<string>',
    'message' => '',
    'model_tier' => 'FAST'
  ]),
  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.neoagent.io/public-api/chat/sessions/{session_id}/messages"

	payload := strings.NewReader("{\n  \"attachments\": [\n    {\n      \"blob_path\": \"<string>\",\n      \"mime\": \"<string>\",\n      \"alt\": \"<string>\",\n      \"filename\": \"<string>\"\n    }\n  ],\n  \"client_message_id\": \"<string>\",\n  \"message\": \"\",\n  \"model_tier\": \"FAST\"\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.neoagent.io/public-api/chat/sessions/{session_id}/messages")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"attachments\": [\n    {\n      \"blob_path\": \"<string>\",\n      \"mime\": \"<string>\",\n      \"alt\": \"<string>\",\n      \"filename\": \"<string>\"\n    }\n  ],\n  \"client_message_id\": \"<string>\",\n  \"message\": \"\",\n  \"model_tier\": \"FAST\"\n}")
  .asString();
require 'uri'
require 'net/http'

url = URI("https://api.neoagent.io/public-api/chat/sessions/{session_id}/messages")

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  \"attachments\": [\n    {\n      \"blob_path\": \"<string>\",\n      \"mime\": \"<string>\",\n      \"alt\": \"<string>\",\n      \"filename\": \"<string>\"\n    }\n  ],\n  \"client_message_id\": \"<string>\",\n  \"message\": \"\",\n  \"model_tier\": \"FAST\"\n}"

response = http.request(request)
puts response.read_body
{
  "data": {
    "chat_turn_id": "<string>",
    "since_cursor": "<string>",
    "user_message_id": "<string>",
    "show_agent_progress_steps": true
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
    "timings_ms": {},
    "pagination": {
      "has_more": true,
      "next_cursor": "<string>"
    },
    "warnings": [
      "<string>"
    ]
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}
{
  "error": {
    "code": "<string>",
    "message": "<string>",
    "details": {}
  },
  "meta": {
    "request_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  }
}

Authorizations

​
Authorization
string
header
required

Authorization: Bearer <token> where <token> is either a neo_sk_<env>_<secret> API key (service account) or a Microsoft Entra ID access token (dashboard user).

Path Parameters

​
session_id
string
required

Body

application/json
​
attachments
PublicChatAttachment · object[]

Images or documents to include with this turn. Each must first be uploaded via POST /chat/sessions/<id>/attachments/upload-url. At most 6 per turn.

​
client_message_id
string | null
​
message
string
default:""
​
model_tier
enum<string>
default:FAST

Speed/quality tier for this turn (ENG-5851): FAST keeps the agent's configured model; SMART escalates a single turn to a stronger model. May be flipped per turn to switch mid-conversation. Defaults to FAST.

Available options:
FAST,
SMART

Response

Success.

​
data
PostMessageResponse · object
required

202 Accepted body — the turn is enqueued, the agent's response streams via SSE.

since_cursor is the Redis-stream event id snapshotted right before this turn was enqueued. Callers tailing /chat/sessions/<id>/events should pass it as ?since=<since_cursor> (or Last-Event-Id: <since_cursor>) so the SSE tail starts strictly after the previous turn's terminal envelopes. Skipping this on a 2nd+ turn against the same session causes the tail to return the previous turn's final state. May be None on the first turn of a fresh session or under Redis failure; consumers treat None as "tail from beginning."

​
meta
object
required