fix(opencode): send official client headers on free-tier requests

Mirror the official opencode CLI fingerprint (User-Agent, x-opencode-session, x-opencode-request, x-opencode-project) on free-tier requests so the Console no longer classifies traffic as an unidentified client and rate-limits it with FreeUsageLimitError / HTTP 429.

Session id resolves conversation-stable via resolveSessionId (client session to assistant-text hash to connection) to preserve prompt caching, normalized into opencode ses_ format with a generated fallback. When the downstream client is already opencode, its headers are forwarded as-is.

open-sse/executors/opencode.js

@@ -1,16 +1,43 @@
+import crypto from "crypto";
 import { BaseExecutor } from "./base.js";
 import { PROVIDERS } from "../config/providers.js";
 import { injectReasoningContent } from "../utils/reasoningContentInjector.js";
+import { resolveSessionId } from "../utils/sessionManager.js";
 
-// Models that use /zen/v1/messages (claude format)
+const OPENCODE_UA = "opencode";
 const MESSAGES_MODELS = new Set();
 
+function generateRequestId() {
+  return `msg_${crypto.randomUUID().replace(/-/g, "")}`;
+}
+
+function generateSessionId() {
+  return `ses_${crypto.randomUUID().replace(/-/g, "")}`;
+}
+
+// Normalize any resolved id into opencode's ses_ format (stable per-conversation)
+function toOpencodeSession(id) {
+  const stripped = String(id || "").replace(/^ses_/, "").replace(/-/g, "");
+  return stripped ? `ses_${stripped}` : null;
+}
+
+function resolveOpencodeSession(body, credentials) {
+  return toOpencodeSession(resolveSessionId({
+    headers: credentials?.rawHeaders,
+    body,
+    connectionId: credentials?.connectionId,
+    scope: "opencode",
+  }));
+}
+
 export class OpenCodeExecutor extends BaseExecutor {
   constructor() {
     super("opencode", PROVIDERS.opencode);
+    this._currentSessionId = null;
   }
 
-  transformRequest(model, body) {
+  transformRequest(model, body, stream, credentials) {
+    this._currentSessionId = resolveOpencodeSession(body, credentials);
     return injectReasoningContent({ provider: this.provider, model, body });
   }
 
@@ -21,12 +48,23 @@ export class OpenCodeExecutor extends BaseExecutor {
       : `${base}/zen/v1/chat/completions`;
   }
 
-  buildHeaders() {
+  buildHeaders(credentials, stream = true) {
+    const raw = credentials?.rawHeaders || {};
+    const lower = {};
+    for (const [k, v] of Object.entries(raw)) lower[k.toLowerCase()] = v;
+
+    const downstreamUa = lower["user-agent"] || "";
+    const isOpencodeDownstream = downstreamUa.toLowerCase().includes("opencode");
+
     return {
       "Content-Type": "application/json",
       "Authorization": "Bearer public",
-      "x-opencode-client": "desktop",
+      "User-Agent": isOpencodeDownstream ? downstreamUa : OPENCODE_UA,
-      "Accept": "text/event-stream"
+      "x-opencode-client": lower["x-opencode-client"] || "desktop",
+      "x-opencode-session": lower["x-opencode-session"] || this._currentSessionId || generateSessionId(),
+      "x-opencode-request": lower["x-opencode-request"] || generateRequestId(),
+      "x-opencode-project": lower["x-opencode-project"] || "global",
+      "Accept": stream ? "text/event-stream" : "*/*",
     };
   }
 }