curl --request POST \
--url https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '{
"mode": "hard"
}'import requests
url = "https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel"
payload = { "mode": "hard" }
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({mode: 'hard'})
};
fetch('https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel', 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}/cancel",
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([
'mode' => 'hard'
]),
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}/cancel"
payload := strings.NewReader("{\n \"mode\": \"hard\"\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}/cancel")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"mode\": \"hard\"\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel")
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 \"mode\": \"hard\"\n}"
response = http.request(request)
puts response.read_body{
"ok": true,
"requested": true,
"status": "running",
"mode": "graceful"
}{
"error": "<string>",
"message": "<string>",
"required_scope": "<string>"
}{
"error": "missing_bearer",
"message": "Authorization required"
}{
"error": "missing_scope",
"required_scope": "sessions:read"
}{
"error": "session_not_found"
}{
"error": {
"type": "rate_limited",
"message": "This API key exceeded its request-rate limit"
}
}Cancel a session
Requests cancellation of a running session. The optional body selects the cancel mode: graceful (default, also used when the body is absent) stops the agent and tries to preserve the workspace with a final snapshot; hard stops immediately and relies on the last verified checkpoint. Sending hard while a graceful cancel is in progress upgrades it. Either way an explicitly cancelled Session ends suspended, never error. Returns whether the request newly flagged (or upgraded) the cancellation.
runcurl --request POST \
--url https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel \
--header 'Authorization: Bearer <token>' \
--header 'Content-Type: application/json' \
--data '{
"mode": "hard"
}'import requests
url = "https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel"
payload = { "mode": "hard" }
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({mode: 'hard'})
};
fetch('https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel', 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}/cancel",
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([
'mode' => 'hard'
]),
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}/cancel"
payload := strings.NewReader("{\n \"mode\": \"hard\"\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}/cancel")
.header("Authorization", "Bearer <token>")
.header("Content-Type", "application/json")
.body("{\n \"mode\": \"hard\"\n}")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.reasonmachines.com/v3/organizations/{orgId}/sessions/{sessionId}/cancel")
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 \"mode\": \"hard\"\n}"
response = http.request(request)
puts response.read_body{
"ok": true,
"requested": true,
"status": "running",
"mode": "graceful"
}{
"error": "<string>",
"message": "<string>",
"required_scope": "<string>"
}{
"error": "missing_bearer",
"message": "Authorization required"
}{
"error": "missing_scope",
"required_scope": "sessions:read"
}{
"error": "session_not_found"
}{
"error": {
"type": "rate_limited",
"message": "This API key exceeded its request-rate limit"
}
}Authorizations
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:debug is privileged: it expands diagnostic session events only for organization owners/admins.
Path Parameters
Organization id or slug. Resolve it with GET /v3/self.
The session id.
Body
graceful (default) stops the agent and tries to preserve the workspace with a final snapshot before the Session ends. hard stops immediately without waiting for a snapshot; the Session resumes from its last verified checkpoint. A later hard request upgrades an in-progress graceful cancel.
graceful, hard Response
Cancellation requested.
True when this request newly flagged, or upgraded, the cancellation.
True when cancellation is requested for the Session.
Current public Session status.
The cancel mode this request asked for.
graceful, hard 
