Send a message - Reason Machines Documentation

Send a message

curl --request POST \
  --url https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data @- <<EOF
{
  "message": "Also bump the timeout to 30s while you're in there.",
  "client_message_id": "follow-up-018f6f3a"
}
EOF

import requests

url = "https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages"

payload = {
    "message": "Also bump the timeout to 30s while you're in there.",
    "client_message_id": "follow-up-018f6f3a"
}
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({
    message: 'Also bump the timeout to 30s while you\'re in there.',
    client_message_id: 'follow-up-018f6f3a'
  })
};

fetch('https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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([
    'message' => 'Also bump the timeout to 30s while you\'re in there.',
    'client_message_id' => 'follow-up-018f6f3a'
  ]),
  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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages"

	payload := strings.NewReader("{\n  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\n}"

response = http.request(request)
puts response.read_body

{
  "ok": true,
  "delivery": "<string>",
  "continuation_session_id": "<string>"
}

POST

organizations

{orgId}

sessions

{sessionId}

messages

Send a message

curl --request POST \
  --url https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data @- <<EOF
{
  "message": "Also bump the timeout to 30s while you're in there.",
  "client_message_id": "follow-up-018f6f3a"
}
EOF

import requests

url = "https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages"

payload = {
    "message": "Also bump the timeout to 30s while you're in there.",
    "client_message_id": "follow-up-018f6f3a"
}
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({
    message: 'Also bump the timeout to 30s while you\'re in there.',
    client_message_id: 'follow-up-018f6f3a'
  })
};

fetch('https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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([
    'message' => 'Also bump the timeout to 30s while you\'re in there.',
    'client_message_id' => 'follow-up-018f6f3a'
  ]),
  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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages"

	payload := strings.NewReader("{\n  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\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.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/messages")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/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  \"message\": \"Also bump the timeout to 30s while you're in there.\",\n  \"client_message_id\": \"follow-up-018f6f3a\"\n}"

response = http.request(request)
puts response.read_body

{
  "ok": true,
  "delivery": "<string>",
  "continuation_session_id": "<string>"
}

Authorizations

Authorization

string

header

required

Your Reason API key from Settings > API. New keys use reason_; legacy ara_ keys remain accepted. Keys are capability-scoped: run, mcp:read, mcp:write, secrets:read, secrets:write, sessions:read, sessions:debug, knowledge:read, memory:read, memory:write, skills:read, skills:write, repos:read, repos:write, reviews:read, reviews:write, deployment:read, analytics:read, org:read, org:write, attachments:read, attachments:write, guardrails:read, guardrails:write, automations:read, automations:write, agent_auth:read. mcp:write manages MCP server configuration only; it does not authorize remote MCP-tool execution. sessions:read reads sessions, including the assistant, reasoning and tool activity in their events. sessions:debug is privileged: only for organization owners/admins, it expands session events to the full diagnostic projection (diagnostic event kinds, status text and raw event metadata).

Path Parameters

orgId

string

required

Organization id or slug. Resolve it with GET /v3/self.

sessionId

string

required

The session id.

Body

application/json

message

string

required

Follow-up instruction, at most 2 MiB when UTF-8 encoded.

client_message_id

string

Caller-generated idempotency key. Reusing it for the same Session returns the original accepted turn.

Required string length: 1 - 160

model

string

Optional model id from GET /agent-auth/models to retry this session on. A model override always starts a new continuation run, because a run's model is fixed at its first execution. Omit or use auto to keep the session's current model.

reasoning_effort

enum<string>

Optional reasoning effort override applied to the continuation run.

Available options:

minimal,

low,

medium,

high,

xhigh,

max

target

object

Moves the Session: this message's turn, and every later one, runs on this target instead of the one the Session was on. Same shape and admission as the create target (cloud, a Device and root, or a named Machine). Only the conversation moves; files on the previous machine do not, unless they were pushed to the Session branch. A move starts a new continuation run, so the Session must have finished its current turn. Any target other than cloud needs the devices:use scope.

Option 1
Option 2
Option 3
Option 4

Show child attributes

Response

Message accepted and delivered or queued for a continuation.

boolean

required

delivery

string

continuation_session_id

string | null

The stable logical Session id after an accepted follow-up. Continue polling this id; Reason may run the turn in a hidden execution Attempt.