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ScaleDown Provider Guide

A provider of decide — the same typed boolean / choice / score answers as TypeSafe's Jev, Laya, XOR, SubQ, Perplexity, Cloudflare Clef and OpenAI Decisions, from ScaleDown's hosted Classify models. It emits no text at all.

Where the facts about ScaleDown come from. Everything this guide says about ScaleDown's endpoint comes from ScaleDown's own documentation and from probes that the marketing session made on 2026-10-15. NeuroLink's project did not probe it: no request to ScaleDown was made in building this provider, and the 200 replies in NeuroLink's tests are stand-ins written from the documented shape, and the error texts in the mocked tests are the ones the marketing session reported. Each item that nobody measured is listed under Not measured.

Overview​

classify-1 is ScaleDown's decision model. You send one state plus named, typed questions. The model answers every question in a single request and returns a typed answer for each, with a probability instead of a sentence. ScaleDown speaks the same System One wire as TypeSafe, so NeuroLink describes it with one catalog file, src/lib/providers/catalog/scaledown.json, and no provider code of its own. NeuroLink calls ScaleDown's public endpoint, so a key alone configures it: there is no base URL to set.

Key Facts​

Provider idscaledown; the alias scaledown-classify names it too
Inference typedecide only
Modelsclassify-1 (the default) and classify, which ScaleDown describes as its latest Classify model. Any other name is refused by ScaleDown with HTTP 422. SCALEDOWN_MODEL sets one
KeySCALEDOWN_API_KEY, or credentials.scaledown.apiKey. The variable is ScaleDown's own: no text provider reads it
Key headerx-api-key: <key>. NeuroLink never sends Authorization: Bearer to ScaleDown
EndpointPOST https://api.scaledown.xyz/v1/scaledown; SCALEDOWN_BASE_URL or credentials.scaledown.baseURL can name another base URL (see Base URL)
Statetext only: a string goes out unchanged, any other value as its JSON text; see How the state is sent
Questions per requestno cap declared
State windownone declared, so nothing is refused locally on size; ScaleDown's input ceiling is not measured
Medianone. Images and video attached to a decide() call are refused before any request; see Images and video
Default timeout5 seconds per attempt; timeoutMs or --timeout replaces it; see Timeouts
Costpriced per input token, input only; see Cost for the rate, its source and its date
Precedencethe last of the eight: used automatically only when none of TypeSafe, Laya, XOR, SubQ, Perplexity, Cloudflare Clef or OpenAI Decisions is configured
StatusNeuroLink lists both models as preview

Quick Start​

1. Get a key​

Create an account and an API key by following ScaleDown's documentation. Sign-up gives a free allowance; its expiry is not established. ScaleDown's documentation says a request made with no credit left returns HTTP 402.

2. Configure​

Set the key in the environment:

export SCALEDOWN_API_KEY=...                       # the key from ScaleDown
export SCALEDOWN_MODEL=classify-1                  # optional
export SCALEDOWN_BASE_URL=https://api.scaledown.xyz  # optional; see "Base URL"

or in the config passed to the SDK, exactly as for any other provider. Values passed per call override the constructor's, which override the environment:

// For the whole instance
const neurolink = new NeuroLink({
  credentials: {
    scaledown: { apiKey: process.env.MY_SCALEDOWN_KEY },
  },
});

// Or for one call
await neurolink.decide({
  provider: "scaledown",
  credentials: {
    scaledown: { apiKey: process.env.MY_SCALEDOWN_KEY },
  },
  state: "We were billed twice for March. Please refund it today.",
  questions: {
    urgent: { type: "boolean", instructions: "Is this urgent?" },
  },
});

credentials.scaledown is its own slice (apiKey and baseURL). A blank SCALEDOWN_API_KEY or credentials.scaledown.apiKey counts as no key.

Base URL​

SCALEDOWN_BASE_URL and credentials.scaledown.baseURL name the part of the URL in front of /v1/scaledown. It can be an origin, such as https://api.scaledown.xyz, or an origin with a path prefix, such as a gateway that forwards https://gateway.example.com/scaledown to ScaleDown. NeuroLink drops trailing slashes and appends /v1/scaledown, so a value that already ends in /v1 would send the request to /v1/v1/scaledown. A blank value is no override. NeuroLink checks nothing else about the value before the request.

3. Use it​

import { NeuroLink, readDecisionChoice } from "@juspay/neurolink";

const neurolink = new NeuroLink();
const result = await neurolink.decide({
  provider: "scaledown",
  state: "We were billed twice for March. Please refund it today.",
  questions: {
    team: {
      type: "choice",
      instructions: "Which team should handle this?",
      criteria: {
        billing: "Payments and refunds",
        technical: "Bugs",
        sales: "Pricing",
      },
    },
    urgent: { type: "boolean", instructions: "Is this urgent?" },
    severity: {
      type: "score",
      instructions: "How severe is the problem?",
      criteria: ["Cosmetic", "Inconvenient", "Customer is blocked"],
    },
  },
});
const team = readDecisionChoice(result.answers, "team");

result.model is the model ScaleDown's reply names, which can differ from the one you asked for (classify is ScaleDown's name for its latest Classify model). result.usage.inputTokens is the reply's usage.input_tokens.

From the CLI​

neurolink decide "We were billed twice for March." --provider scaledown \
  --questions '{"urgent":{"type":"boolean","instructions":"Is this urgent?"}}'

The text output ends with a Cost: line, priced from the input tokens the reply reports (see Cost).

How a request is sent​

ScaleDown's wire is System One's, so you write the same questions as for any other decide provider.

NeuroLinkSent to /v1/scaledown
the keythe header x-api-key: <key>, beside Content-Type: application/json; there is no Authorization header
the modelmodel in the body (classify-1 unless you set another)
statestate, always a string; see below
booleana noul question with its instructions
choicea choice question; criteria maps each option name to its description
scorea score question; criteria is an ordered list of level descriptions

The reply has the System One shape, an answers object keyed by question id, plus model and usage (input_tokens, output_tokens and a cost in USD). A boolean answer carries a probability. A choice or score answer carries the confidence the reply reports and a probability for each option or level; when a reply omits the confidence, NeuroLink uses the highest probability in that answer's distribution instead. Whether ScaleDown's confidence is calibrated is not established, so tune a threshold on it against your own labelled data.

ScaleDown's documentation describes a score question's criteria as an ordered list of 2 to 10 level descriptions. NeuroLink does not enforce that.

How the state is sent​

ScaleDown's documentation says it reads only the text and document fields of the state, and treats a string state as shorthand for { "text": <the string> }. NeuroLink therefore sends the state as a string, whatever you pass:

You passScaleDown receives
a stringthe string, unchanged (not trimmed)
an object, an array, a number, a booleanits JSON text, as one string (JSON.stringify)
{} or []the two-character text {} or []
a string that is empty or only whitespacenothing: refused locally, before any request

Two consequences:

  • An object state is classified as text. ScaleDown does not read an object's other keys, so { "title": "...", "review": "..." } reaches it as the JSON text of that object, and an object that has a text field is not unwrapped either. If you want it to read plain prose, pass a string.
  • {} and [] are not refused. They are non-blank text, so they are sent and ScaleDown classifies the literal characters. ScaleDown itself answers HTTP 422 ('state.text' or 'state.document' must be provided) to an empty or text-less state object, as the marketing session saw on 2026-10-15, but NeuroLink never sends one. Check for an empty container yourself if you want it refused.

A blank string is refused as an invalid_request, with a message that names ScaleDown and the rule (needs non-blank state text) and never repeats the state. decide() rejects with it, tryDecide() returns null, and no request is made. This is a catalog setting, decide.stateEncoding: see How the catalog entry says this.

Choice options and billing​

ScaleDown's documentation says every option of a choice question is scored by a separate internal call, so the input tokens a request is charged for grow with the number of options times the length of the state. The marketing session reported two data points on 2026-10-15, not measured here: about 1,829 input tokens for a 20-option choice and about 13,059 for a 255-option choice, each on a one-sentence state.

NeuroLink declares no cap on options. A probe by the marketing session saw a 255-option choice answered and a 300-option choice refused with HTTP 502; the limit between them is not mapped. When ScaleDown answers a request with HTTP 502, as it did to the 300-option probe, NeuroLink reports a server error, retries once, and every built-in consumer then treats the decision as failed and falls back. Whether a refused request is charged is not established. Keep the number of options of a choice question modest, and see Cost.

Every built-in consumer of decide — model routing, relevance-driven compaction, tool routing and RAG planning — asks for the default decision provider. That is the first one that is configured, in the environment or in the credentials passed to the SDK, in the order TypeSafe, Laya, XOR, SubQ, Perplexity, Cloudflare Clef, OpenAI Decisions, then ScaleDown. ScaleDown counts with its key alone. So:

  • Only a ScaleDown key: built-in features use ScaleDown, and each of their decisions is then a paid request (see Cost) that still falls back to what NeuroLink did before on any failure.
  • A ScaleDown key, plus any earlier provider's key: built-in features use that earlier provider. ScaleDown runs only where a caller asks for provider: "scaledown".
  • A blank SCALEDOWN_API_KEY: no key. ScaleDown is not configured.
  • provider: "scaledown" with no key: an authentication error and no request.

ScaleDown is last on purpose, and its key is not shared. Apart from ScaleDown, the providers that come after SubQ in the order are the ones whose key is also read by a text provider (Perplexity's, the Cloudflare pair and OpenAI's), placed behind it so that a key set only for a text provider cannot displace a decision provider a host set up on purpose. That reasoning does not cover ScaleDown, whose key belongs to no other provider: it was placed last, after OpenAI Decisions, as a deliberate choice and not by that rule. The effect is that an ambient OPENAI_API_KEY, PERPLEXITY_API_KEY or Cloudflare pair in the environment outranks a SCALEDOWN_API_KEY set on purpose. A host that wants ScaleDown for the built-in features must not have the earlier providers configured, or must name it in its own calls.

The classifier router's auto strategy counts SCALEDOWN_API_KEY too: with only that key set, auto resolves to jev and ScaleDown answers.

How the catalog entry says this​

scaledown.json needed two optional keys in its decide block that no earlier entry set, both read by the shared catalog engine for any entry that sets them. An entry that omits them behaves exactly as before.

KeyValueWhat it does
authHeader"x-api-key"The API key is sent as x-api-key: <key> and no Authorization header is sent at all. "bearer", the default when the key is omitted, sends Authorization: Bearer <key>. This is the decide request's own setting; quirks.authHeaderStyle belongs to the chat path and is not read here
stateEncoding"text"The state that goes out is always a string: a string is sent unchanged (not trimmed), any other value as its JSON text, and a state that is blank after trimming is refused before any request as an invalid_request. Omitted means the state goes out as given

The rest of the entry is the same kind of data every decide entry carries: the system-one dialect, order 8, the endpoint {baseURL}/v1/scaledown, the model in the body, trailing slashes dropped from the base URL, and the error rules in the table below. The fields are also described in the generated API reference, under DecideBlock.

Images and video​

ScaleDown's endpoint reads text only, and the catalog entry declares no media. An image or a video attached to a decide() call for ScaleDown is refused before any request, as an invalid_request, and the catalog marks both models vision: false. This refusal comes before the blank-state check, so a call that carries media is always refused for the media. To decide over images today, use XOR, Perplexity, Cloudflare Clef or OpenAI Decisions.

Timeouts​

The default is 5,000 ms per attempt (the shared decide default, DEFAULT_DECISION_TIMEOUT_MS). A choice question is scored once per option, and the marketing session saw one ScaleDown 504 (Endpoint request timed out) after about 29 seconds. ScaleDown's own latency is not measured here, so a caller with many options or a long state should pass timeoutMs.

A 504 that ScaleDown sends is classified timeout and is not retried. A timeout raised by NeuroLink's own clock is retried once.

Cost​

List price: USD 0.05 per million input tokens, with output tokens not charged, from ScaleDown's launch post and from the usage.cost in a response, as reported to this project by the marketing session on 2026-10-15. This project has not priced a call itself and has not checked the rate since, so check ScaleDown's dashboard for the current one.

NeuroLink prices a decision from the input tokens the reply reports, at that one rate, and counts output tokens at nothing. It does not read the reply's usage.cost. result.usage and the CLI's Cost: line are therefore an estimate from the list price, not a bill. A reply that reports no usage is priced at zero. The sign-up allowance is a free allowance whose expiry is not established.

Errors​

ScaleDown's documentation lists HTTP 402 (insufficient credits), 422 (invalid), 502 (model service error) and 504 (timeout). The marketing session also saw, on 2026-10-15, a 429 Max queue length has been reached (no rate-limit headers; it cleared after a few seconds) and a 504 Endpoint request timed out, and each was answered when it retried by hand. NeuroLink shows the detail text of an error body, whether it is a plain string or an object with a message. A body in any other form, such as a detail that is an array, gives only ScaleDown request failed with HTTP <status>; the kind and the retry behaviour do not change.

ReplyKindRetried
401authentication — the provider instance stops retryingno
402invalid_request — the account has no creditno
422invalid_request, with ScaleDown's reason when the body shows oneno
429rate_limityes, once
502serveryes, once
504timeoutno
other 5xxserveryes, once
any other statusinvalid_requestno
no response within the timeouttimeoutyes, once
the request fails before any reply (DNS, connection)networkyes, once
a blank string state (local)invalid_request, with no network callno
an image or a video (local)invalid_request, with no network callno
no key configured (local)authentication, with no network callno

Only a 401 stops the instance, because a bad key does not fix itself: after the first rejection that instance sends no more requests, and a new NeuroLink instance asks again. Because neurolink.decide() and neurolink.tryDecide() build a fresh provider for every call, the latch holds only for a provider instance you keep, not across public calls. A 402 and a 422 do not latch: after you add credit or fix the request, the same instance works again.

An error message never carries the API key. Before the message of an error reply reaches a log or an error, NeuroLink removes the configured key (if ScaleDown echoes it in a body), anything shaped like a key beginning sk-, long hex runs and embedded data: URLs.

Data retention​

NeuroLink has not read ScaleDown's data-handling terms. The state and the questions of every request go to api.scaledown.xyz, including the ones the built-in consumers send for model routing, compaction, tool routing and RAG planning whenever ScaleDown is the default decision provider. Read ScaleDown's terms before sending anything sensitive.

Not measured​

Each item below is not measured by NeuroLink: nothing it was built or tested from says what the endpoint does beyond the marketing session's probes, and no request was made to ScaleDown for this project.

  1. Context size and input ceiling, for either model. The catalog records a contextWindow of 128000 and a maxOutputTokens of 1 for classify-1, and both are placeholders the catalog schema requires. 128000 is NeuroLink's own default window for a model it knows nothing about, and 1 is the figure SubQ's entry uses for a model that returns no text. Neither is a ScaleDown statement, and the entry declares no decisionLimits, so nothing is refused locally on the size of a state.
  2. Latency, for any size of state or number of options. The 5-second default is the shared decide default, not a measurement of ScaleDown.
  3. Rate limits. A 429 Max queue length has been reached, with no rate-limit headers, was seen by the marketing session on 2026-10-15; no limit is mapped.
  4. The maximum number of options in a choice, of questions per request, and of levels in a score, and what ScaleDown does with a list longer than the 2 to 10 levels its documentation describes.
  5. Whether classify moves to a newer model, and what that would change in an answer.
  6. Accuracy of its answers against any other decide provider, and whether its confidences are calibrated.
  7. How long the free allowance lasts. Its expiry is not established.
  8. Whether a request ScaleDown refuses (an HTTP 502, 422 or 504) is charged.
  9. ScaleDown's data-retention terms.

What has and has not been checked​

  • Read or probed by the marketing session on 2026-10-15, not by this project: ScaleDown's documentation (the endpoint, the model names, the question kinds, the documented error statuses and the price); a request that sent the key as a Bearer token answered HTTP 401 {"detail":"x-api-key header is required"}; a model name other than classify or classify-1 answered HTTP 422; a state with no text or document answered HTTP 422; the 255-option and 300-option choice requests above; the 429 and the 504 above.
  • In this project: the whole behaviour of the entry is tested against stand-in replies: the mocked provider suite (the request headers, body and URL, every status above, the state rules, the order), the decide provider contract (test/fixtures/decide/scaledown/contract.json, whose rows are all stand-ins and none claims to have been seen live), and a CLI run against a local server on 127.0.0.1. None of them reaches ScaleDown.
  • Not captured: any real reply from ScaleDown. The catalog entry records no live matrix.

Troubleshooting​

  • ScaleDown requires an API key — set SCALEDOWN_API_KEY, or pass credentials.scaledown.apiKey. A blank value counts as unset.
  • A 401 — ScaleDown rejected the key, and the message carries its text. Check the key. neurolink.decide() builds a fresh provider for every call, so the next call asks again; only a provider instance you keep stops sending after a rejection.
  • A 402 — ScaleDown's documentation says this means no credit is left. Add credit and call again; the same instance works again.
  • A 422 — ScaleDown refused the request. The message carries its reason when the body shows one; a model name other than classify or classify-1 is one cause.
  • ScaleDown needs non-blank state text — the state was an empty string or only whitespace. Nothing was sent.
  • ScaleDown does not accept images or video — ScaleDown reads text only. Use a decision provider that reads images.
  • A 502 on a choice question with very many options — a probe by the marketing session saw a 300-option choice refused this way. Send fewer options.
  • A 504 / timeout — see Timeouts. Pass a larger timeoutMs.
  • A request to /v1/v1/scaledown — SCALEDOWN_BASE_URL ends in /v1. Drop it.
  • Built-in routing never uses ScaleDown — an earlier provider is also configured and takes precedence (see When NeuroLink uses it), or no key is set.
  • A question is missing from result.answers — the reply left it out, or its answer could not be read. An answer that could not be read is logged as a warning that names the question and never quotes the reply; a question the reply leaves out entirely is not logged, so look for it in result.answers.

See also​