feat: add /v1/completions legacy endpoint + show all 3 OpenAI endpoints in dashboard

- New route /v1/completions: accepts prompt string (legacy) + messages array
  Normalizes prompt format to chat/completions format automatically
- EndpointPageClient: Added 3rd card (Completions Legacy) in Core APIs section
  Dashboard now shows: /v1/chat/completions, /v1/responses, /v1/completions
- i18n: completionsLegacy/completionsLegacyDesc synced to 30 languages

CHANGELOG.md

@@ -1,5 +1,20 @@
 # Changelog
 
+## [2.3.8] - 2026-03-12
+
+## [2.3.9] - 2026-03-12
+
+### Added
+
+- **/v1/completions**: New legacy OpenAI completions endpoint — accepts both `prompt` string and `messages` array, normalizes to chat format automatically
+- **EndpointPage**: Now shows all 3 OpenAI-compatible endpoint types: Chat Completions, Responses API, and Legacy Completions
+- **i18n**: Added `completionsLegacy/completionsLegacyDesc` to 30 language files
+
+### Fixed
+
+- **OAuthModal**: Fix `[object Object]` displayed on all OAuth connection errors — properly extract `.message` from error response objects in all 3 `throw new Error(data.error)` calls (exchange, device-code, authorize)
+- Affects Cline, Codex, GitHub, Qwen, Kiro, and all other OAuth providers
+
 ## [2.3.7] - 2026-03-12
 
 ### Fixed

package.json

@@ -1,6 +1,6 @@
 {
   "name": "omniroute",
-  "version": "2.3.7",
+  "version": "2.3.9",
   "description": "Smart AI Router with auto fallback — route to FREE & cheap models, zero downtime. Works with Cursor, Cline, Claude Desktop, Codex, and any OpenAI-compatible tool.",
   "type": "module",
   "bin": {

src/app/(dashboard)/dashboard/endpoint/EndpointPageClient.tsx

@@ -446,6 +446,27 @@ export default function APIPageClient({ machineId }) {
                 copied={copied}
                 baseUrl={currentEndpoint}
               />
+
+              {/* Legacy Completions */}
+              <EndpointSection
+                icon="text_fields"
+                iconColor="text-orange-500"
+                iconBg="bg-orange-500/10"
+                title={t("completionsLegacy") || "Completions (Legacy)"}
+                path="/v1/completions"
+                description={
+                  t("completionsLegacyDesc") ||
+                  "Legacy OpenAI text completions — accepts both prompt and messages format"
+                }
+                models={endpointData.chat}
+                expanded={expandedEndpoint === "completions"}
+                onToggle={() =>
+                  setExpandedEndpoint(expandedEndpoint === "completions" ? null : "completions")
+                }
+                copy={copy}
+                copied={copied}
+                baseUrl={currentEndpoint}
+              />
             </div>
           </div>
 

src/app/api/v1/completions/route.ts

@@ -0,0 +1,97 @@
+import { CORS_ORIGIN, CORS_HEADERS } from "@/shared/utils/cors";
+import { handleChat } from "@/sse/handlers/chat";
+import { initTranslators } from "@omniroute/open-sse/translator/index.ts";
+import { createInjectionGuard } from "@/middleware/promptInjectionGuard";
+
+let initPromise = null;
+const injectionGuard = createInjectionGuard();
+
+function ensureInitialized() {
+  if (!initPromise) {
+    initPromise = Promise.resolve(initTranslators()).then(() => {
+      console.log("[SSE] Translators initialized");
+    });
+  }
+  return initPromise;
+}
+
+/**
+ * Handle CORS preflight
+ */
+export async function OPTIONS() {
+  return new Response(null, {
+    headers: {
+      "Access-Control-Allow-Origin": CORS_ORIGIN,
+      "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
+      "Access-Control-Allow-Headers": "*",
+    },
+  });
+}
+
+/**
+ * POST /v1/completions — Legacy OpenAI Completions API
+ *
+ * Accepts both the modern chat format (messages[]) and the legacy
+ * text-completions format (prompt string). Legacy requests are
+ * automatically normalized to chat/completions format before routing.
+ *
+ * @see https://platform.openai.com/docs/api-reference/completions
+ */
+export async function POST(request: Request) {
+  await ensureInitialized();
+
+  // Prompt injection guard
+  try {
+    const cloned = request.clone();
+    const body = await cloned.json().catch(() => null);
+    if (body) {
+      const { blocked, result } = injectionGuard(body);
+      if (blocked) {
+        return new Response(
+          JSON.stringify({
+            error: {
+              message: "Request blocked: potential prompt injection detected",
+              type: "injection_detected",
+              code: "SECURITY_001",
+              detections: result.detections.length,
+            },
+          }),
+          { status: 400, headers: { ...CORS_HEADERS, "Content-Type": "application/json" } }
+        );
+      }
+
+      // Normalize legacy completions format: { prompt, model } → { messages, model }
+      // If the body has `prompt` but no `messages`, convert to chat format.
+      if (body.prompt !== undefined && !body.messages) {
+        const prompt = Array.isArray(body.prompt) ? body.prompt.join("\n") : String(body.prompt);
+        const normalized = {
+          ...body,
+          messages: [{ role: "user", content: prompt }],
+        };
+        delete normalized.prompt;
+
+        const newRequest = new Request(request.url, {
+          method: request.method,
+          headers: request.headers,
+          body: JSON.stringify(normalized),
+        });
+        return await handleChat(newRequest);
+      }
+    }
+  } catch (error) {
+    console.error("[SECURITY] Prompt injection guard failed:", error);
+    return new Response(
+      JSON.stringify({
+        error: {
+          message: "Security validation temporarily unavailable",
+          type: "security_guard_unavailable",
+          code: "SECURITY_002",
+        },
+      }),
+      { status: 503, headers: { ...CORS_HEADERS, "Content-Type": "application/json" } }
+    );
+  }
+
+  // Standard path: body already has messages[] (chat format)
+  return await handleChat(request);
+}

src/i18n/messages/ar.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "البدء السريع",
     "a2aQuickStartStep1": "اكتشف بطاقة الوكيل على `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "إرسال طلبات JSON - RPC إلى@@ PH0 @@ باستخدام @@PH1 @@ أو `message/stream`.",
-    "a2aQuickStartStep3": "تتبع المهام والتحكم فيها باستخدام `tasks/get` و `tasks/cancel`."
+    "a2aQuickStartStep3": "تتبع المهام والتحكم فيها باستخدام `tasks/get` و `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "جارٍ تحميل لوحة تحكم MCP...",

src/i18n/messages/bg.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "Button text: start playing a game",
     "a2aQuickStartStep1": "Открийте картата на агента на @@PH0 @@.",
     "a2aQuickStartStep2": "Изпратете JSON - RPC заявки до@@ PH0 @@, като използвате @@ PH1 @@ или @@ PH2 @@.",
-    "a2aQuickStartStep3": "Проследяване и контрол на задачите с помощта на @@ PH0 @@ и @@ PH1 @@."
+    "a2aQuickStartStep3": "Проследяване и контрол на задачите с помощта на @@ PH0 @@ и @@ PH1 @@.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Зареждане на таблото за управление на MCP...",

src/i18n/messages/da.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "Hurtig start",
     "a2aQuickStartStep1": "Find agentkortet på`/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC-anmodninger til`POST /a2a`vedhjælp af `message/send` eller `message/stream`.",
-    "a2aQuickStartStep3": "Spor og kontroller opgaver ved hjælp af `tasks/get` og `tasks/cancel`."
+    "a2aQuickStartStep3": "Spor og kontroller opgaver ved hjælp af `tasks/get` og `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Indlæser MCP-dashboard...",

src/i18n/messages/de.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A-Schnellstart",
     "a2aQuickStartStep1": "Entdecken Sie die Agentenkarte unter `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Senden Sie JSON-RPC-Anfragen an `POST /a2a` mit `message/send` oder `message/stream`.",
-    "a2aQuickStartStep3": "Verfolgen und steuern Sie Aufgaben mit `tasks/get` und `tasks/cancel`."
+    "a2aQuickStartStep3": "Verfolgen und steuern Sie Aufgaben mit `tasks/get` und `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "MCP-Dashboard wird geladen...",

src/i18n/messages/en.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "endpoints": {
     "tabProxy": "Endpoint Proxy",

src/i18n/messages/es.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "Inicio rápido de A2A",
     "a2aQuickStartStep1": "Descubra la tarjeta de agente en `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Envíe solicitudes JSON-RPC a `POST /a2a` usando `message/send` o `message/stream`.",
-    "a2aQuickStartStep3": "Realice un seguimiento y controle las tareas utilizando `tasks/get` y `tasks/cancel`."
+    "a2aQuickStartStep3": "Realice un seguimiento y controle las tareas utilizando `tasks/get` y `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Cargando el panel de MCP...",

src/i18n/messages/fi.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Pikaopas",
     "a2aQuickStartStep1": "Tutustu agenttikorttiin osoitteessa `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Lähetä JSON-RPC-pyynnöt osoitteeseen `POST /a2a` käyttämällä `message/send` tai `message/stream`.",
-    "a2aQuickStartStep3": "Seuraa ja ohjaa tehtäviä käyttämällä `tasks/get` ja `tasks/cancel`."
+    "a2aQuickStartStep3": "Seuraa ja ohjaa tehtäviä käyttämällä `tasks/get` ja `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Ladataan MCP-hallintapaneelia...",

src/i18n/messages/fr.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "Démarrage rapide A2A",
     "a2aQuickStartStep1": "Découvrez la carte d'agent sur `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Envoyez des requêtes JSON-RPC à `POST /a2a` en utilisant `message/send` ou `message/stream`.",
-    "a2aQuickStartStep3": "Suivez et contrôlez les tâches à l’aide de `tasks/get` et `tasks/cancel`."
+    "a2aQuickStartStep3": "Suivez et contrôlez les tâches à l’aide de `tasks/get` et `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Chargement du tableau de bord MCP...",

src/i18n/messages/he.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/hu.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Kövesse nyomon és vezérelje a feladatokat a `tasks/get` és `tasks/cancel` használatával."
+    "a2aQuickStartStep3": "Kövesse nyomon és vezérelje a feladatokat a `tasks/get` és `tasks/cancel` használatával.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/id.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/in.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/it.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/ja.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/ko.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/ms.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Mula Pantas",
     "a2aQuickStartStep1": "Temui kad ejen di `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Hantar permintaan JSON-RPC ke `POST /a2a` menggunakan `message/send` atau `message/stream`.",
-    "a2aQuickStartStep3": "Jejak dan kawal tugas menggunakan `tasks/get` dan `tasks/cancel`."
+    "a2aQuickStartStep3": "Jejak dan kawal tugas menggunakan `tasks/get` dan `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/nl.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/no.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A hurtigstart",
     "a2aQuickStartStep1": "Oppdag agentkortet på `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC-forespørsler til `POST /a2a` ved å bruke `message/send` eller `message/stream`.",
-    "a2aQuickStartStep3": "Spor og kontroller oppgaver ved å bruke `tasks/get` og `tasks/cancel`."
+    "a2aQuickStartStep3": "Spor og kontroller oppgaver ved å bruke `tasks/get` og `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Laster inn MCP-dashbordet ...",

src/i18n/messages/phi.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Subaybayan at kontrolin ang mga gawain gamit ang `tasks/get` at `tasks/cancel`."
+    "a2aQuickStartStep3": "Subaybayan at kontrolin ang mga gawain gamit ang `tasks/get` at `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Nilo-load ang MCP dashboard...",

src/i18n/messages/pl.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/pt-BR.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Início rápido",
     "a2aQuickStartStep1": "Descubra o agent card em `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Envie requisições JSON-RPC para `POST /a2a` usando `message/send` ou `message/stream`.",
-    "a2aQuickStartStep3": "Acompanhe e controle tarefas com `tasks/get` e `tasks/cancel`."
+    "a2aQuickStartStep3": "Acompanhe e controle tarefas com `tasks/get` e `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Carregando painel MCP...",

src/i18n/messages/pt.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "endpoints": {
     "tabProxy": "Endpoint Proxy",

src/i18n/messages/ro.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/ru.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/sk.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/sv.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/th.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/uk-UA.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/vi.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/i18n/messages/zh-CN.json

@@ -858,7 +858,9 @@
     "a2aQuickStartTitle": "A2A Quick Start",
     "a2aQuickStartStep1": "Discover the agent card at `/.well-known/agent.json`.",
     "a2aQuickStartStep2": "Send JSON-RPC requests to `POST /a2a` using `message/send` or `message/stream`.",
-    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`."
+    "a2aQuickStartStep3": "Track and control tasks using `tasks/get` and `tasks/cancel`.",
+    "completionsLegacy": "Completions (Legacy)",
+    "completionsLegacyDesc": "Legacy OpenAI text completions — accepts both prompt string and messages array format"
   },
   "mcpDashboard": {
     "loading": "Loading MCP dashboard...",

src/shared/components/OAuthModal.tsx

@@ -87,7 +87,13 @@ export default function OAuthModal({
         });
 
         const data = await res.json();
-        if (!res.ok) throw new Error(data.error);
+        if (!res.ok) {
+          const errMsg =
+            typeof data.error === "object" && data.error !== null
+              ? (data.error as any).message || JSON.stringify(data.error)
+              : data.error || "Exchange failed";
+          throw new Error(errMsg);
+        }
 
         setStep("success");
         onSuccess?.();
@@ -180,7 +186,13 @@ export default function OAuthModal({
 
         const res = await fetch(`/api/oauth/${provider}/device-code`);
         const data = await res.json();
-        if (!res.ok) throw new Error(data.error);
+        if (!res.ok) {
+          const errMsg =
+            typeof data.error === "object" && data.error !== null
+              ? (data.error as any).message || JSON.stringify(data.error)
+              : data.error || "Request failed";
+          throw new Error(errMsg);
+        }
 
         setDeviceData(data);
 
@@ -281,7 +293,13 @@ export default function OAuthModal({
         `/api/oauth/${provider}/authorize?redirect_uri=${encodeURIComponent(redirectUri)}`
       );
       const data = await res.json();
-      if (!res.ok) throw new Error(data.error);
+      if (!res.ok) {
+        const errMsg =
+          typeof data.error === "object" && data.error !== null
+            ? (data.error as any).message || JSON.stringify(data.error)
+            : data.error || "Authorization failed";
+        throw new Error(errMsg);
+      }
 
       setAuthData({ ...data, redirectUri });