feat(providers): add System One (Jev) decision endpoint

New /v1/systemone pass-through route for Jev decision models (jev-1.13,
jev-1.13-free) on OpenCode Zen and the free lane. Follows the media-route
pattern: systemoneConfig in the registry drives URL/headers, the handler
mirrors the embeddings account-fallback + usage flow, and the dashboard
gains a System One media-provider kind. No chat-pipeline changes.

Co-Authored-By: Claude Code <noreply@anthropic.com>

open-sse/handlers/systemoneCore.js

@@ -0,0 +1,95 @@
+import { createErrorResult, parseUpstreamError, formatProviderError } from "../utils/error.js";
+import { HTTP_STATUS, FETCH_CONNECT_TIMEOUT_MS } from "../config/runtimeConfig.js";
+import { PROVIDER_MEDIA } from "../providers/index.js";
+import { generateSessionId } from "../executors/opencode-zen.js";
+
+/**
+ * Core System One (Jev) handler — native decision payload pass-through.
+ * URL/headers come from the registry's systemoneConfig; body and JSON response
+ * are forwarded untouched (decision models have no chat translation layer).
+ *
+ * @returns {Promise<{ success: boolean, response: Response, usage?: object, status?: number, error?: string }>}
+ */
+export async function handleSystemoneCore({
+  body,
+  modelInfo,
+  credentials,
+  log,
+  onRequestSuccess,
+}) {
+  const { provider, model } = modelInfo;
+  const cfg = PROVIDER_MEDIA[provider]?.systemoneConfig;
+  if (!cfg?.baseUrl) {
+    return createErrorResult(
+      HTTP_STATUS.BAD_REQUEST,
+      `Provider '${provider}' does not support System One.`
+    );
+  }
+
+  // Validate input at the trust boundary; question-level shape is upstream's job.
+  if (body.state === undefined || body.state === null) {
+    return createErrorResult(HTTP_STATUS.BAD_REQUEST, "Missing required field: state");
+  }
+  if (!body.questions || typeof body.questions !== "object" || Array.isArray(body.questions)) {
+    return createErrorResult(HTTP_STATUS.BAD_REQUEST, "Missing required field: questions");
+  }
+
+  // noAuth free lanes carry accessToken "public" from the credential stub.
+  const token = credentials?.apiKey || credentials?.accessToken;
+  const headers = {
+    "Content-Type": "application/json",
+    ...(token ? { Authorization: `Bearer ${token}` } : {}),
+    ...(cfg.headers || {}),
+    // Zen lanes expect the official client session header on every request.
+    "x-opencode-session": generateSessionId(),
+  };
+  const requestBody = { ...body, model };
+
+  log?.debug?.("SYSTEMONE", `${provider.toUpperCase()} | ${model}`);
+
+  let providerResponse;
+  try {
+    providerResponse = await fetch(cfg.baseUrl, {
+      method: "POST",
+      headers,
+      body: JSON.stringify(requestBody),
+      ...(typeof AbortSignal?.timeout === "function"
+        ? { signal: AbortSignal.timeout(FETCH_CONNECT_TIMEOUT_MS) }
+        : {}),
+    });
+  } catch (error) {
+    const errMsg = formatProviderError(error, provider, model, HTTP_STATUS.BAD_GATEWAY);
+    log?.debug?.("SYSTEMONE", `Fetch error: ${errMsg}`);
+    return createErrorResult(HTTP_STATUS.BAD_GATEWAY, errMsg);
+  }
+
+  if (!providerResponse.ok) {
+    const { statusCode, message } = await parseUpstreamError(providerResponse);
+    const errMsg = formatProviderError(new Error(message), provider, model, statusCode);
+    log?.debug?.("SYSTEMONE", `Provider error: ${errMsg}`);
+    return createErrorResult(statusCode, errMsg);
+  }
+
+  let responseBody;
+  try {
+    responseBody = await providerResponse.json();
+  } catch {
+    return createErrorResult(HTTP_STATUS.BAD_GATEWAY, `Invalid JSON response from ${provider}`);
+  }
+
+  if (onRequestSuccess) await onRequestSuccess();
+
+  const usage = responseBody?.usage;
+  return {
+    success: true,
+    usage: usage
+      ? { prompt_tokens: usage.input_tokens || 0, completion_tokens: usage.output_tokens || 0 }
+      : null,
+    response: new Response(JSON.stringify(responseBody), {
+      headers: {
+        "Content-Type": "application/json",
+        "Access-Control-Allow-Origin": "*",
+      },
+    }),
+  };
+}

open-sse/providers/index.js

@@ -23,7 +23,7 @@ function buildTransport(transport, oauth) {
 const MEDIA_KEYS = new Set([
   "serviceKinds", "ttsConfig", "sttConfig", "embeddingConfig",
   "imageConfig", "imageToTextConfig", "videoConfig", "musicConfig",
-  "searchViaChat", "searchConfig", "fetchConfig",
+  "searchViaChat", "searchConfig", "fetchConfig", "systemoneConfig",
   "modelsFetcher", "mediaPriority", "hiddenKinds",
 ]);
 

open-sse/providers/registry/opencode-zen.js

@@ -106,7 +106,6 @@ export default {
     { id: "union-alpha", name: "Union Alpha", supportedFormats: ["claude"] },
     // Free tier on the keyed lane (chat completions)
     { id: "deepseek-v4-flash-free", name: "DeepSeek V4 Flash Free", supportedFormats: ["openai"] },
-    { id: "mimo-v2.6-flash-free", name: "MiMo V2.6 Flash Free", supportedFormats: ["openai"] },
     { id: "mimo-v2.5-free", name: "MiMo V2.5 Free", supportedFormats: ["openai"] },
     { id: "ling-3.0-flash-fin-free", name: "Ling 3.0 Flash Fin Free", supportedFormats: ["openai"] },
     { id: "nemotron-3-ultra-free", name: "Nemotron 3 Ultra Free", supportedFormats: ["openai"] },

open-sse/providers/registry/opencode.js

@@ -28,7 +28,16 @@ export default {
     { id: "muse-spark-1.2-contributor-free", name: "Muse Spark 1.2 Contributor Free", targetFormat: "openai-responses" },
     { id: "muse-spark-1.3-contributor-free", name: "Muse Spark 1.3 Contributor Free", targetFormat: "openai-responses" },
     { id: "union-alpha", name: "Union Alpha Free", targetFormat: "claude" },
+    { id: "jev-1.13-free", name: "Jev 1.13 Free", kind: "decision" },
   ],
+  serviceKinds: ["llm", "systemone"],
+  systemoneConfig: {
+    baseUrl: "https://opencode.ai/zen/v1/systemone",
+    headers: {
+      "x-opencode-client": "desktop",
+      "User-Agent": "opencode/1.18.31",
+    },
+  },
   modelsFetcher: { url: "https://opencode.ai/zen/v1/models", type: "opencode-free" },
   passthroughModels: true,
 };