Fledge Alpha

stealth/fledge-alpha is a free-tier stealth preview that arrived on OpenCode Zen on 1 October 2026. It takes text and images and returns text over a 1,048,576-token context window, with a 131,072-token maximum output, tool calling, and reasoning you can set to low, high, or max — those three are the only efforts published for it. It is available through BYOK keys (Novita or OpenRouter), both of which list it at $0.

It is deliberately undocumented: no lab, no specifications, and no benchmarks are published for the model, so treat it as an experiment rather than a model you can evaluate up front. The only route is OpenCode Zen's free pool (fledge-alpha-free), which is a shared, rate-limited pool — expect FreeUsageLimitError under load, and a BYOK mirror of the same wire if you hold your own OpenCode Zen key. It is not on OpenRouter or Nous, so there is no second route to fall back to yet.

• App code — Vercel AI SDK or OpenAI SDK.
• Coding agent — anyr claude / anyr opencode / anyr codex (playbook).
• No code — playground.

Try it in the Vercel AI SDK. createAnyRouter() reads ANYROUTER_API_KEY:

import { createAnyRouter } from "@anyr/ai-sdk-provider"
import { generateText } from "ai"

const anyrouter = createAnyRouter()

const { reasoning, text } = await generateText({
  model: anyrouter("stealth/fledge-alpha"),
  prompt: "Explain what this regex does, then show an input it rejects.",
  reasoning: "high",
})
console.log(reasoning, text)

The SDK's portable reasoning enum stops at xhigh, so low and high map straight across but max does not have a slot in it. Reach max through extraBody, which is merged into the request body last:

const { text } = await generateText({
  model: anyrouter("stealth/fledge-alpha"),
  prompt: "Review this diff and list the three riskiest changes.",
  providerOptions: {
    anyrouter: { extraBody: { reasoning_effort: "max" } },
  },
})
console.log(text)

Already on the OpenAI SDK? OpenAI SDK playbook:

import OpenAI from "openai"

const client = new OpenAI({
  baseURL: "https://anyrouter.dev/api/v1",
  apiKey: process.env.ANYROUTER_API_KEY,
})

const res = await client.chat.completions.create({
  model: "stealth/fledge-alpha",
  messages: [{ role: "user", content: "Hello" }],
})
console.log(res.choices[0]?.message.content)

curl https://anyrouter.dev/api/v1/chat/completions \
  -H "Authorization: Bearer $ANYROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"stealth/fledge-alpha","messages":[{"role":"user","content":"Hello"}]}'

Or launch a coding agent through the anyr CLI:

curl -fsSL https://anyrouter.dev/setup.sh | bash
anyr login
anyr claude --model "stealth/fledge-alpha"

curl -fsSL https://anyrouter.dev/setup.sh | bash
anyr login
anyr opencode --model "stealth/fledge-alpha"

curl -fsSL https://anyrouter.dev/setup.sh | bash
anyr login
anyr codex --model "stealth/fledge-alpha"

More: AI SDK · OpenAI SDK · coding agents.