Inference completion callback (internal)

curl --request POST \
  --url https://api.trycarhub.com/internal/callbacks/modal \
  --header 'Content-Type: application/json' \
  --header 'X-Modal-Signature: <x-modal-signature>' \
  --data '
{
  "job_id": "job_3ZxK9pQr7TnW",
  "output_ref": "s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json",
  "units_actual": 1,
  "model_version": "plate-reader@2026-08-01",
  "error": {
    "code": "model_inference_failed",
    "message": "<string>"
  },
  "provider_job_id": "<string>",
  "duration_ms": 1
}
'

import requests

url = "https://api.trycarhub.com/internal/callbacks/modal"

payload = {
    "job_id": "job_3ZxK9pQr7TnW",
    "output_ref": "s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json",
    "units_actual": 1,
    "model_version": "plate-reader@2026-08-01",
    "error": {
        "code": "model_inference_failed",
        "message": "<string>"
    },
    "provider_job_id": "<string>",
    "duration_ms": 1
}
headers = {
    "X-Modal-Signature": "<x-modal-signature>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-Modal-Signature': '<x-modal-signature>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    job_id: 'job_3ZxK9pQr7TnW',
    output_ref: 's3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json',
    units_actual: 1,
    model_version: 'plate-reader@2026-08-01',
    error: {code: 'model_inference_failed', message: '<string>'},
    provider_job_id: '<string>',
    duration_ms: 1
  })
};

fetch('https://api.trycarhub.com/internal/callbacks/modal', 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.trycarhub.com/internal/callbacks/modal",
  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([
    'job_id' => 'job_3ZxK9pQr7TnW',
    'output_ref' => 's3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json',
    'units_actual' => 1,
    'model_version' => 'plate-reader@2026-08-01',
    'error' => [
        'code' => 'model_inference_failed',
        'message' => '<string>'
    ],
    'provider_job_id' => '<string>',
    'duration_ms' => 1
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-Modal-Signature: <x-modal-signature>"
  ],
]);

$response = curl_exec($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.trycarhub.com/internal/callbacks/modal"

	payload := strings.NewReader("{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-Modal-Signature", "<x-modal-signature>")
	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.trycarhub.com/internal/callbacks/modal")
  .header("X-Modal-Signature", "<x-modal-signature>")
  .header("Content-Type", "application/json")
  .body("{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.trycarhub.com/internal/callbacks/modal")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-Modal-Signature"] = '<x-modal-signature>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}"

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

Internal

Inference completion callback (internal)

Not part of the public API. Called by the inference plane when a submitted unit of work settles. Authenticated by an HMAC-SHA256 of the raw body in X-Modal-Signature, keyed with a shared secret; unsigned or stale (> 5 min skew) calls are rejected with 401.

The callback is what closes the billing loop: units_actual is the real billable count (the per-detection meter is only knowable here), and the gateway commits that amount and releases the rest of the reservation in the same transaction. Deliveries are at-least-once and must be treated as idempotent on (job_id, status).

POST

internal

callbacks

modal

Inference completion callback (internal)

curl --request POST \
  --url https://api.trycarhub.com/internal/callbacks/modal \
  --header 'Content-Type: application/json' \
  --header 'X-Modal-Signature: <x-modal-signature>' \
  --data '
{
  "job_id": "job_3ZxK9pQr7TnW",
  "output_ref": "s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json",
  "units_actual": 1,
  "model_version": "plate-reader@2026-08-01",
  "error": {
    "code": "model_inference_failed",
    "message": "<string>"
  },
  "provider_job_id": "<string>",
  "duration_ms": 1
}
'

import requests

url = "https://api.trycarhub.com/internal/callbacks/modal"

payload = {
    "job_id": "job_3ZxK9pQr7TnW",
    "output_ref": "s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json",
    "units_actual": 1,
    "model_version": "plate-reader@2026-08-01",
    "error": {
        "code": "model_inference_failed",
        "message": "<string>"
    },
    "provider_job_id": "<string>",
    "duration_ms": 1
}
headers = {
    "X-Modal-Signature": "<x-modal-signature>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {'X-Modal-Signature': '<x-modal-signature>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    job_id: 'job_3ZxK9pQr7TnW',
    output_ref: 's3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json',
    units_actual: 1,
    model_version: 'plate-reader@2026-08-01',
    error: {code: 'model_inference_failed', message: '<string>'},
    provider_job_id: '<string>',
    duration_ms: 1
  })
};

fetch('https://api.trycarhub.com/internal/callbacks/modal', 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.trycarhub.com/internal/callbacks/modal",
  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([
    'job_id' => 'job_3ZxK9pQr7TnW',
    'output_ref' => 's3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json',
    'units_actual' => 1,
    'model_version' => 'plate-reader@2026-08-01',
    'error' => [
        'code' => 'model_inference_failed',
        'message' => '<string>'
    ],
    'provider_job_id' => '<string>',
    'duration_ms' => 1
  ]),
  CURLOPT_HTTPHEADER => [
    "Content-Type: application/json",
    "X-Modal-Signature: <x-modal-signature>"
  ],
]);

$response = curl_exec($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.trycarhub.com/internal/callbacks/modal"

	payload := strings.NewReader("{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("X-Modal-Signature", "<x-modal-signature>")
	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.trycarhub.com/internal/callbacks/modal")
  .header("X-Modal-Signature", "<x-modal-signature>")
  .header("Content-Type", "application/json")
  .body("{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.trycarhub.com/internal/callbacks/modal")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["X-Modal-Signature"] = '<x-modal-signature>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"job_id\": \"job_3ZxK9pQr7TnW\",\n  \"output_ref\": \"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json\",\n  \"units_actual\": 1,\n  \"model_version\": \"plate-reader@2026-08-01\",\n  \"error\": {\n    \"code\": \"model_inference_failed\",\n    \"message\": \"<string>\"\n  },\n  \"provider_job_id\": \"<string>\",\n  \"duration_ms\": 1\n}"

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

Headers

t=<epoch>,v1=<hex hmac-sha256 of "<t>.<raw body>">.

Body

application/json

Payload posted by the inference plane when a unit of work settles. Internal contract, not part of the public API surface.

job_id

string

required

Job identifier — job_ followed by a base58 string.

Pattern: ^job_[1-9A-HJ-NP-Za-km-z]{8,32}$

Example:

"job_3ZxK9pQr7TnW"

status

enum<string>

required

Terminal state reached by the inference call.

Available options:

succeeded,

failed

output_ref

string | null

Storage key of the serialised result written by the worker. Required when status is succeeded.

Example:

"s3://carhub-out/2026/08/16/job_3ZxK9pQr7TnW.json"

units_actual

integer | null

Billable units really consumed. Only the worker knows this for the per-detection meter; the gateway commits exactly this amount and releases the rest.

Required range: x >= 0

model_version

string | null

Build that produced the output, surfaced on the job.

Example:

"plate-reader@2026-08-01"

error

object | null

Populated when status is failed.

Show child attributes

provider_job_id

string | null

Identifier on the inference provider's side, for cross-system tracing.

duration_ms

integer | null

Wall-clock time of the inference call, fed into latency metrics.

Required range: x >= 0

Response

Callback accepted.

⌘I

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Inference completion callback (internal)

Headers

Body

Response