diff --git a/src/app/(dashboard)/dashboard/providers/[id]/AddApiKeyModal.js b/src/app/(dashboard)/dashboard/providers/[id]/AddApiKeyModal.js
index 0a272045..11c9be78 100644
--- a/src/app/(dashboard)/dashboard/providers/[id]/AddApiKeyModal.js
+++ b/src/app/(dashboard)/dashboard/providers/[id]/AddApiKeyModal.js
@@ -47,7 +47,7 @@ export default function AddApiKeyModal({ isOpen, provider, providerName, isCompa
 
   const [mode, setMode] = useState("single"); // "single" | "bulk"
   const [bulkText, setBulkText] = useState("");
-  const [bulkResult, setBulkResult] = useState(null); // { success, failed }
+  const [bulkResult, setBulkResult] = useState(null); // { success, failed, duplicateLines }
 
   const buildProviderSpecificData = () => {
     if (isOllamaLocal && formData.ollamaHostUrl.trim()) {
@@ -137,6 +137,7 @@ export default function AddApiKeyModal({ isOpen, provider, providerName, isCompa
     setBulkResult(null);
     let success = 0;
     let failed = 0;
+    const duplicateLines = [];
     for (let i = 0; i < lines.length; i++) {
       const parts = lines[i].split("|");
       const baseName = parts.length >= 2 ? parts[0].trim() : "Key";
@@ -165,14 +166,20 @@ export default function AddApiKeyModal({ isOpen, provider, providerName, isCompa
             ...(providerSpecificData ? { providerSpecificData } : {}),
           }),
         });
-        if (res.ok) success++;
-        else failed++;
+        if (res.ok) {
+          success++;
+        } else {
+          failed++;
+          const data = await res.json().catch(() => null);
+          if (res.status === 409) duplicateLines.push(i + 1);
+          if (data?.error) console.log(`Bulk API key add failed on line ${i + 1}:`, data.error);
+        }
       } catch {
         failed++;
       }
     }
     setSaving(false);
-    setBulkResult({ success, failed });
+    setBulkResult({ success, failed, duplicateLines });
     if (success > 0 && onBulkDone) onBulkDone();
   };
 
@@ -203,7 +210,14 @@ export default function AddApiKeyModal({ isOpen, provider, providerName, isCompa
             />
             {bulkResult && (
               <div className={`text-sm font-medium ${bulkResult.failed > 0 ? "text-yellow-400" : "text-green-400"}`}>
-                ✓ {bulkResult.success} added{bulkResult.failed > 0 ? `, ✗ ${bulkResult.failed} failed` : ""}
+                <p>
+                  ✓ {bulkResult.success} added{bulkResult.failed > 0 ? `, ✗ ${bulkResult.failed} failed` : ""}
+                </p>
+                {bulkResult.duplicateLines.length > 0 && (
+                  <p className="mt-1 text-red-500">
+                    Account/API key already exists in the system (line{bulkResult.duplicateLines.length > 1 ? "s" : ""} {bulkResult.duplicateLines.join(", ")}).
+                  </p>
+                )}
               </div>
             )}
             <div className="flex gap-2">
diff --git a/src/app/(dashboard)/dashboard/providers/page.js b/src/app/(dashboard)/dashboard/providers/page.js
index dd134f33..958c4f10 100644
--- a/src/app/(dashboard)/dashboard/providers/page.js
+++ b/src/app/(dashboard)/dashboard/providers/page.js
@@ -22,6 +22,7 @@ import Link from "next/link";
 import { getErrorCode, getRelativeTime } from "@/shared/utils";
 import { useNotificationStore } from "@/store/notificationStore";
 import { useHeaderSearchStore } from "@/store/headerSearchStore";
+import useUserStore from "@/store/userStore";
 import ModelAvailabilityBadge from "./components/ModelAvailabilityBadge";
 import AddCompatibleModal from "./components/AddCompatibleModal";
 
@@ -105,6 +106,7 @@ export default function ProvidersPage() {
   const [testingMode, setTestingMode] = useState(null);
   const [testResults, setTestResults] = useState(null);
   const notify = useNotificationStore();
+  const user = useUserStore((state) => state.user);
   const searchQuery = useHeaderSearchStore((s) => s.query);
   const registerSearch = useHeaderSearchStore((s) => s.register);
   const unregisterSearch = useHeaderSearchStore((s) => s.unregister);
@@ -281,12 +283,18 @@ export default function ProvidersPage() {
     "oauth",
   );
   const freeEntries = Object.entries(FREE_PROVIDERS)
-    .filter(([, info]) => !info.hidden && matchSearch(info.name))
+    .filter(
+      ([, info]) =>
+        !info.hidden &&
+        (user?.role === "admin" || !info.noAuth) &&
+        matchSearch(info.name),
+    )
     .sort(([, a], [, b]) => (b.noAuth ? 1 : 0) - (a.noAuth ? 1 : 0));
   const freeTierEntries = sortByPriority(
     Object.entries(FREE_TIER_PROVIDERS).filter(
       ([, info]) =>
         !info.hidden &&
+        (user?.role === "admin" || !info.noAuth) &&
         matchSearch(info.name) &&
         (info.serviceKinds ?? ["llm"]).includes("llm"),
     ),
diff --git a/src/app/api/oauth/[provider]/[action]/route.js b/src/app/api/oauth/[provider]/[action]/route.js
index 57bff272..2edc3932 100644
--- a/src/app/api/oauth/[provider]/[action]/route.js
+++ b/src/app/api/oauth/[provider]/[action]/route.js
@@ -7,6 +7,7 @@ import {
   pollForToken 
 } from "@/lib/oauth/providers";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 import {
   startCodexProxy,
   stopCodexProxy,
@@ -20,7 +21,7 @@ import {
   clearXaiSession,
 } from "@/lib/oauth/utils/server";
 
-async function completeXaiManualCode(code, state) {
+async function completeXaiManualCode(code, state, ownerId) {
   const session = state ? getXaiSessionStatus(state) : null;
   if (!session) {
     throw new Error("xAI OAuth session not found; restart the login flow and paste the code again");
@@ -38,6 +39,7 @@ async function completeXaiManualCode(code, state) {
     const connection = await createProviderConnection({
       provider: "xai",
       authType: "oauth",
+      ownerId,
       ...tokenData,
       expiresAt: tokenData.expiresIn
         ? new Date(Date.now() + tokenData.expiresIn * 1000).toISOString()
@@ -68,6 +70,7 @@ async function completeXaiManualCode(code, state) {
 // GET /api/oauth/[provider]/device-code - Request device code (for device_code flow)
 export async function GET(request, { params }) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { provider, action } = await params;
     const { searchParams } = new URL(request.url);
 
@@ -98,8 +101,8 @@ export async function GET(request, { params }) {
       let serverSide = false;
       if (result.success && state && codeVerifier && redirectUri) {
         serverSide = provider === "xai"
-          ? registerXaiSession({ state, codeVerifier, redirectUri })
-          : registerCodexSession({ state, codeVerifier, redirectUri });
+          ? registerXaiSession({ state, codeVerifier, redirectUri, ownerId: user.id })
+          : registerCodexSession({ state, codeVerifier, redirectUri, ownerId: user.id });
       }
       return NextResponse.json({ ...result, serverSide });
     }
@@ -178,6 +181,9 @@ export async function GET(request, { params }) {
 
     return NextResponse.json({ error: "Unknown action" }, { status: 400 });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("OAuth GET error:", error);
     return NextResponse.json({ error: error.message }, { status: 500 });
   }
@@ -187,6 +193,7 @@ export async function GET(request, { params }) {
 // POST /api/oauth/[provider]/poll - Poll for token (device_code flow)
 export async function POST(request, { params }) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { provider, action } = await params;
     let body;
     try {
@@ -223,6 +230,7 @@ export async function POST(request, { params }) {
         const connection = await createProviderConnection({
           provider,
           authType: "access_token",
+          ownerId: user.id,
           accessToken: code,
           email: email || null,
           providerSpecificData,
@@ -253,6 +261,7 @@ export async function POST(request, { params }) {
       const connection = await createProviderConnection({
         provider,
         authType: "oauth",
+        ownerId: user.id,
         ...tokenData,
         expiresAt: tokenData.expiresIn 
           ? new Date(Date.now() + tokenData.expiresIn * 1000).toISOString() 
@@ -307,6 +316,7 @@ export async function POST(request, { params }) {
         const connection = await createProviderConnection({
           provider,
           authType: "oauth",
+          ownerId: user.id,
           ...result.tokens,
           expiresAt: result.tokens.expiresIn 
             ? new Date(Date.now() + result.tokens.expiresIn * 1000).toISOString() 
@@ -339,13 +349,20 @@ export async function POST(request, { params }) {
         return NextResponse.json({ error: "Manual code only supported for xai" }, { status: 400 });
       }
       const { code, state } = body;
-      const connection = await completeXaiManualCode(String(code || "").trim(), String(state || "").trim());
+      const connection = await completeXaiManualCode(
+        String(code || "").trim(),
+        String(state || "").trim(),
+        user.id,
+      );
       return NextResponse.json({ success: true, connection });
     }
 
     return NextResponse.json({ error: "Unknown action" }, { status: 400 });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("OAuth POST error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/oauth/codex/bulk-import/route.js b/src/app/api/oauth/codex/bulk-import/route.js
index 42d5341f..5cba4f48 100644
--- a/src/app/api/oauth/codex/bulk-import/route.js
+++ b/src/app/api/oauth/codex/bulk-import/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { createProviderConnection } from "@/models";
 import { extractCodexAccountInfo } from "@/lib/oauth/providers";
+import { requireCurrentDashboardUser } from "@/lib/auth/currentUser";
 
 /**
  * POST /api/oauth/codex/bulk-import
@@ -17,6 +18,16 @@ import { extractCodexAccountInfo } from "@/lib/oauth/providers";
  * Tokens are NEVER echoed back in the response.
  */
 export async function POST(request) {
+  let user;
+  try {
+    user = await requireCurrentDashboardUser();
+  } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
+    return NextResponse.json({ error: "Failed to authenticate user" }, { status: 500 });
+  }
+
   let body;
   try {
     body = await request.json();
@@ -64,6 +75,7 @@ export async function POST(request) {
         id: _id,
         provider: _provider,
         authType: _authType,
+        ownerId: _ownerId,
         createdAt: _createdAt,
         updatedAt: _updatedAt,
         ...item
@@ -106,13 +118,14 @@ export async function POST(request) {
       const created = await createProviderConnection({
         provider: "codex",
         authType: "oauth",
+        ownerId: user.id,
         ...item,
       });
 
       results.push({ index: i, ok: true, id: created.id });
       success++;
     } catch (e) {
-      results.push({ index: i, ok: false, error: e.message || "Unknown error" });
+      results.push({ index: i, ok: false, error: e.message || "Unknown error", status: e.status || null });
       failed++;
     }
   }
diff --git a/src/app/api/oauth/codex/import-token/route.js b/src/app/api/oauth/codex/import-token/route.js
index 73e80d52..84458898 100644
--- a/src/app/api/oauth/codex/import-token/route.js
+++ b/src/app/api/oauth/codex/import-token/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { createProviderConnection } from "@/models";
 import { extractCodexAccountInfo } from "@/lib/oauth/providers";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/codex/import-token
@@ -11,6 +12,7 @@ import { extractCodexAccountInfo } from "@/lib/oauth/providers";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { accessToken, name } = await request.json();
 
     if (!accessToken || typeof accessToken !== "string") {
@@ -71,6 +73,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "codex",
       authType: "access_token",
+      ownerId: user.id,
       accessToken: token,
       name: connectionName,
       email: email,
@@ -90,7 +93,10 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Codex access token import error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/oauth/cursor/import/route.js b/src/app/api/oauth/cursor/import/route.js
index a1695e92..68240453 100644
--- a/src/app/api/oauth/cursor/import/route.js
+++ b/src/app/api/oauth/cursor/import/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { CursorService } from "@/lib/oauth/services/cursor";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/cursor/import
@@ -12,6 +13,7 @@ import { createProviderConnection } from "@/models";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { accessToken, machineId } = await request.json();
 
     if (!accessToken || typeof accessToken !== "string") {
@@ -43,6 +45,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "cursor",
       authType: "oauth",
+      ownerId: user.id,
       accessToken: tokenData.accessToken,
       refreshToken: null, // Cursor doesn't have public refresh endpoint
       expiresAt: new Date(Date.now() + tokenData.expiresIn * 1000).toISOString(),
@@ -65,8 +68,11 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Cursor import token error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
 
diff --git a/src/app/api/oauth/gitlab/pat/route.js b/src/app/api/oauth/gitlab/pat/route.js
index 286ddc24..e901b525 100644
--- a/src/app/api/oauth/gitlab/pat/route.js
+++ b/src/app/api/oauth/gitlab/pat/route.js
@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 const GITLAB_DEFAULT_BASE = "https://gitlab.com";
 
@@ -9,6 +10,7 @@ const GITLAB_DEFAULT_BASE = "https://gitlab.com";
  */
 export async function POST(request) {
   try {
+    const { user: dashboardUser } = await getProviderConnectionAccess();
     let body;
     try {
       body = await request.json();
@@ -39,6 +41,7 @@ export async function POST(request) {
     await createProviderConnection({
       provider: "gitlab",
       authType: "oauth",
+      ownerId: dashboardUser.id,
       accessToken: token.trim(),
       refreshToken: null,
       expiresAt: null,
@@ -56,7 +59,10 @@ export async function POST(request) {
 
     return NextResponse.json({ success: true });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.error("GitLab PAT auth error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/oauth/iflow/cookie/route.js b/src/app/api/oauth/iflow/cookie/route.js
index fe0ea979..f164be41 100644
--- a/src/app/api/oauth/iflow/cookie/route.js
+++ b/src/app/api/oauth/iflow/cookie/route.js
@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * iFlow Cookie-Based Authentication
@@ -8,6 +9,7 @@ import { createProviderConnection } from "@/models";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { cookie } = await request.json();
 
     if (!cookie || typeof cookie !== "string") {
@@ -109,6 +111,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "iflow",
       authType: "cookie",
+      ownerId: user.id,
       name: refreshedKey.name || keyData.name,
       email: refreshedKey.name || keyData.name,
       apiKey: refreshedKey.apiKey,
@@ -131,7 +134,10 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.error("iFlow cookie auth error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/oauth/kiro/api-key/route.js b/src/app/api/oauth/kiro/api-key/route.js
index 139df9b5..a5a417da 100644
--- a/src/app/api/oauth/kiro/api-key/route.js
+++ b/src/app/api/oauth/kiro/api-key/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { KiroService } from "@/lib/oauth/services/kiro";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/kiro/api-key
@@ -10,6 +11,7 @@ import { createProviderConnection } from "@/models";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { apiKey, region } = await request.json();
 
     if (!apiKey || typeof apiKey !== "string" || !apiKey.trim()) {
@@ -35,6 +37,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "kiro",
       authType: "api_key",
+      ownerId: user.id,
       accessToken: credential.accessToken,
       refreshToken: null,
       expiresAt: new Date(Date.now() + 365 * 24 * 60 * 60 * 1000).toISOString(),
@@ -57,7 +60,13 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Kiro API key import error:", error);
+    if (error.status === 409) {
+      return NextResponse.json({ error: error.message }, { status: 409 });
+    }
     // Do not reflect upstream response body to the client (SSRF hardening)
     return NextResponse.json(
       { error: "API key validation failed" },
diff --git a/src/app/api/oauth/kiro/import-cli-proxy/route.js b/src/app/api/oauth/kiro/import-cli-proxy/route.js
index d71d6a7c..7572fd88 100644
--- a/src/app/api/oauth/kiro/import-cli-proxy/route.js
+++ b/src/app/api/oauth/kiro/import-cli-proxy/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { createProviderConnection } from "@/models";
 import { normalizeKiroExternalIdpAuth } from "@/lib/oauth/kiroExternalIdp";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/kiro/import-cli-proxy
@@ -8,6 +9,7 @@ import { normalizeKiroExternalIdpAuth } from "@/lib/oauth/kiroExternalIdp";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const body = await request.json();
     const rawAuth = body?.cliProxyAuth ?? body?.auth ?? body?.json ?? body;
     const tokenData = normalizeKiroExternalIdpAuth(rawAuth);
@@ -15,6 +17,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "kiro",
       authType: "oauth",
+      ownerId: user.id,
       accessToken: tokenData.accessToken,
       refreshToken: tokenData.refreshToken,
       expiresAt: tokenData.expiresAt,
@@ -32,9 +35,12 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     return NextResponse.json(
       { error: error?.message || "CLIProxyAPI import failed" },
-      { status: 400 }
+      { status: error?.status || 400 }
     );
   }
 }
diff --git a/src/app/api/oauth/kiro/import/route.js b/src/app/api/oauth/kiro/import/route.js
index 46383410..df1b17ef 100644
--- a/src/app/api/oauth/kiro/import/route.js
+++ b/src/app/api/oauth/kiro/import/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { KiroService } from "@/lib/oauth/services/kiro";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/kiro/import
@@ -10,6 +11,7 @@ import { createProviderConnection } from "@/models";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { refreshToken, clientId, clientSecret, region, authMethod, profileArn } = await request.json();
 
     if (!refreshToken || typeof refreshToken !== "string") {
@@ -38,6 +40,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "kiro",
       authType: "oauth",
+      ownerId: user.id,
       accessToken: tokenData.accessToken,
       refreshToken: tokenData.refreshToken || refreshToken.trim(),
       expiresAt: new Date(Date.now() + (tokenData.expiresIn || 3600) * 1000).toISOString(),
@@ -60,7 +63,10 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Kiro import token error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/oauth/kiro/social-exchange/route.js b/src/app/api/oauth/kiro/social-exchange/route.js
index a99f276e..d4a79a0f 100644
--- a/src/app/api/oauth/kiro/social-exchange/route.js
+++ b/src/app/api/oauth/kiro/social-exchange/route.js
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { KiroService } from "@/lib/oauth/services/kiro";
 import { createProviderConnection } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/oauth/kiro/social-exchange
@@ -9,6 +10,7 @@ import { createProviderConnection } from "@/models";
  */
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const { code, codeVerifier, provider } = await request.json();
 
     if (!code || !codeVerifier) {
@@ -40,6 +42,7 @@ export async function POST(request) {
     const connection = await createProviderConnection({
       provider: "kiro",
       authType: "oauth",
+      ownerId: user.id,
       accessToken: tokenData.accessToken,
       refreshToken: tokenData.refreshToken,
       expiresAt: new Date(Date.now() + tokenData.expiresIn * 1000).toISOString(),
@@ -61,7 +64,10 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Kiro social exchange error:", error);
-    return NextResponse.json({ error: error.message }, { status: 500 });
+    return NextResponse.json({ error: error.message }, { status: error.status || 500 });
   }
 }
diff --git a/src/app/api/providers/[id]/models/route.js b/src/app/api/providers/[id]/models/route.js
index 52f0291b..c8d35d72 100644
--- a/src/app/api/providers/[id]/models/route.js
+++ b/src/app/api/providers/[id]/models/route.js
@@ -1,5 +1,6 @@
 import { NextResponse } from "next/server";
 import { getProviderConnectionById } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 import { isOpenAICompatibleProvider, isAnthropicCompatibleProvider } from "@/shared/constants/providers";
 import { GEMINI_CONFIG } from "@/lib/oauth/constants/oauth";
 import { refreshGoogleToken, updateProviderCredentials } from "@/sse/services/tokenRefresh";
@@ -393,7 +394,8 @@ const PROVIDER_MODELS_CONFIG = {
 export async function GET(request, { params }) {
   try {
     const { id } = await params;
-    const connection = await getProviderConnectionById(id);
+    const { ownerId } = await getProviderConnectionAccess();
+    const connection = await getProviderConnectionById(id, ownerId);
 
     if (!connection) {
       return NextResponse.json({ error: "Connection not found" }, { status: 404 });
@@ -546,6 +548,9 @@ export async function GET(request, { params }) {
       models
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error fetching provider models:", error);
     return NextResponse.json({ error: "Failed to fetch models" }, { status: 500 });
   }
diff --git a/src/app/api/providers/[id]/route.js b/src/app/api/providers/[id]/route.js
index 6ab51797..0d980f22 100644
--- a/src/app/api/providers/[id]/route.js
+++ b/src/app/api/providers/[id]/route.js
@@ -5,6 +5,7 @@ import {
   updateProviderConnection,
   deleteProviderConnection,
 } from "@/models";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 function normalizeProxyConfig(body = {}) {
   const hasAnyProxyField =
@@ -63,7 +64,8 @@ function shouldMergeProviderSpecificData(existing, incoming, hasLegacyProxy, has
 export async function GET(request, { params }) {
   try {
     const { id } = await params;
-    const connection = await getProviderConnectionById(id);
+    const { ownerId } = await getProviderConnectionAccess();
+    const connection = await getProviderConnectionById(id, ownerId);
 
     if (!connection) {
       return NextResponse.json({ error: "Connection not found" }, { status: 404 });
@@ -78,6 +80,9 @@ export async function GET(request, { params }) {
 
     return NextResponse.json({ connection: result });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error fetching connection:", error);
     return NextResponse.json({ error: "Failed to fetch connection" }, { status: 500 });
   }
@@ -87,6 +92,7 @@ export async function GET(request, { params }) {
 export async function PUT(request, { params }) {
   try {
     const { id } = await params;
+    const { ownerId } = await getProviderConnectionAccess();
     const body = await request.json();
     const {
       name,
@@ -101,7 +107,7 @@ export async function PUT(request, { params }) {
       providerSpecificData
     } = body;
 
-    const existing = await getProviderConnectionById(id);
+    const existing = await getProviderConnectionById(id, ownerId);
     if (!existing) {
       return NextResponse.json({ error: "Connection not found" }, { status: 404 });
     }
@@ -166,6 +172,9 @@ export async function PUT(request, { params }) {
 
     return NextResponse.json({ connection: result });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error updating connection:", error);
     return NextResponse.json({ error: "Failed to update connection" }, { status: 500 });
   }
@@ -175,6 +184,12 @@ export async function PUT(request, { params }) {
 export async function DELETE(request, { params }) {
   try {
     const { id } = await params;
+    const { ownerId } = await getProviderConnectionAccess();
+
+    const existing = await getProviderConnectionById(id, ownerId);
+    if (!existing) {
+      return NextResponse.json({ error: "Connection not found" }, { status: 404 });
+    }
 
     const deleted = await deleteProviderConnection(id);
     if (!deleted) {
@@ -183,6 +198,9 @@ export async function DELETE(request, { params }) {
 
     return NextResponse.json({ message: "Connection deleted successfully" });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error deleting connection:", error);
     return NextResponse.json({ error: "Failed to delete connection" }, { status: 500 });
   }
diff --git a/src/app/api/providers/[id]/test-models/route.js b/src/app/api/providers/[id]/test-models/route.js
index 84946396..235827aa 100644
--- a/src/app/api/providers/[id]/test-models/route.js
+++ b/src/app/api/providers/[id]/test-models/route.js
@@ -4,6 +4,7 @@ import { getProviderModels, PROVIDER_ID_TO_ALIAS } from "open-sse/config/provide
 import { isOpenAICompatibleProvider, isAnthropicCompatibleProvider } from "@/shared/constants/providers";
 import { UPDATER_CONFIG } from "@/shared/constants/config";
 import { pingModelByKind } from "@/app/api/models/test/ping";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 /**
  * POST /api/providers/[id]/test-models
@@ -13,7 +14,8 @@ import { pingModelByKind } from "@/app/api/models/test/ping";
 export async function POST(request, { params }) {
   try {
     const { id } = await params;
-    const connection = await getProviderConnectionById(id);
+    const { ownerId } = await getProviderConnectionAccess();
+    const connection = await getProviderConnectionById(id, ownerId);
     if (!connection) {
       return NextResponse.json({ error: "Connection not found" }, { status: 404 });
     }
@@ -60,6 +62,9 @@ export async function POST(request, { params }) {
 
     return NextResponse.json({ provider: providerId, connectionId: id, results });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error testing models:", error);
     return NextResponse.json({ error: "Test failed" }, { status: 500 });
   }
diff --git a/src/app/api/providers/[id]/test/route.js b/src/app/api/providers/[id]/test/route.js
index 0fa641a3..a3f65e2c 100644
--- a/src/app/api/providers/[id]/test/route.js
+++ b/src/app/api/providers/[id]/test/route.js
@@ -1,10 +1,17 @@
 import { NextResponse } from "next/server";
 import { testSingleConnection } from "./testUtils.js";
+import { getProviderConnectionById } from "@/lib/localDb";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 // POST /api/providers/[id]/test - Test connection
 export async function POST(request, { params }) {
   try {
     const { id } = await params;
+    const { ownerId } = await getProviderConnectionAccess();
+    const connection = await getProviderConnectionById(id, ownerId);
+    if (!connection) {
+      return NextResponse.json({ error: "Connection not found" }, { status: 404 });
+    }
     const result = await testSingleConnection(id);
 
     if (result.error === "Connection not found") {
@@ -17,6 +24,9 @@ export async function POST(request, { params }) {
       refreshed: result.refreshed || false,
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error testing connection:", error);
     return NextResponse.json({ error: "Test failed" }, { status: 500 });
   }
diff --git a/src/app/api/providers/client/route.js b/src/app/api/providers/client/route.js
index be5342c1..81e67fe5 100644
--- a/src/app/api/providers/client/route.js
+++ b/src/app/api/providers/client/route.js
@@ -2,6 +2,7 @@ import { NextResponse } from "next/server";
 import { getProviderConnections } from "@/lib/localDb";
 import { backfillCodexEmails } from "@/lib/oauth/providers";
 import { USAGE_APIKEY_PROVIDERS, USAGE_SUPPORTED_PROVIDERS } from "@/shared/constants/providers";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 const SAFE_FIELDS = [
   "id", "provider", "authType", "name", "email", "displayName",
@@ -76,6 +77,7 @@ function sortConnections(connections, sort) {
 
 export async function GET(request) {
   try {
+    const { ownerId } = await getProviderConnectionAccess();
     await backfillCodexEmails();
 
     const { searchParams } = new URL(request.url);
@@ -85,7 +87,7 @@ export async function GET(request) {
     const page = parsePositiveInt(searchParams.get("page"), 1);
     const pageSize = Math.min(parsePositiveInt(searchParams.get("pageSize"), DEFAULT_PAGE_SIZE), MAX_PAGE_SIZE);
 
-    const allConnections = await getProviderConnections();
+    const allConnections = await getProviderConnections(ownerId ? { ownerId } : {});
     const eligibleConnections = allConnections.filter(isUsageEligible);
     const providerOptions = Array.from(new Set(eligibleConnections.map((conn) => conn.provider))).sort();
 
@@ -121,6 +123,9 @@ export async function GET(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error fetching providers for client:", error);
     return NextResponse.json({ error: "Failed to fetch providers" }, { status: 500 });
   }
diff --git a/src/app/api/providers/route.js b/src/app/api/providers/route.js
index 5885472b..a1b5b054 100644
--- a/src/app/api/providers/route.js
+++ b/src/app/api/providers/route.js
@@ -9,6 +9,7 @@ import {
 import { APIKEY_PROVIDERS } from "@/shared/constants/config";
 import { AI_PROVIDERS, FREE_TIER_PROVIDERS, WEB_COOKIE_PROVIDERS, isOpenAICompatibleProvider, isAnthropicCompatibleProvider, isCustomEmbeddingProvider } from "@/shared/constants/providers";
 import { normalizeProviderId, normalizeProviderSpecificData } from "@/lib/providerNormalization";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 export const dynamic = "force-dynamic";
 
@@ -49,7 +50,8 @@ async function normalizeProxyPoolId(proxyPoolId) {
 // GET /api/providers - List all connections
 export async function GET() {
   try {
-    const connections = await getProviderConnections();
+    const { ownerId } = await getProviderConnectionAccess();
+    const connections = await getProviderConnections(ownerId ? { ownerId } : {});
 
     // Build nodeNameMap for compatible providers (id → name)
     let nodeNameMap = {};
@@ -78,6 +80,9 @@ export async function GET() {
 
     return NextResponse.json({ connections: safeConnections });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error fetching providers:", error);
     return NextResponse.json({ error: "Failed to fetch providers" }, { status: 500 });
   }
@@ -86,6 +91,7 @@ export async function GET() {
 // POST /api/providers - Create new connection (API Key only, OAuth via separate flow)
 export async function POST(request) {
   try {
+    const { user } = await getProviderConnectionAccess();
     const body = await request.json();
     const provider = normalizeProviderId(body.provider);
     const { apiKey, name, displayName, priority, globalPriority, defaultModel, testStatus } = body;
@@ -175,6 +181,7 @@ export async function POST(request) {
     const newConnection = await createProviderConnection({
       provider,
       authType: isWebCookieProvider ? "cookie" : "apikey",
+      ownerId: user.id,
       name: connectionName,
       apiKey: apiKey || "",
       priority: priority || 1,
@@ -191,7 +198,13 @@ export async function POST(request) {
 
     return NextResponse.json({ connection: result }, { status: 201 });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error creating provider:", error);
-    return NextResponse.json({ error: "Failed to create provider" }, { status: 500 });
+    return NextResponse.json(
+      { error: error.status === 409 ? error.message : "Failed to create provider" },
+      { status: error.status || 500 },
+    );
   }
 }
diff --git a/src/app/api/providers/test-batch/route.js b/src/app/api/providers/test-batch/route.js
index da020cc7..deba3303 100644
--- a/src/app/api/providers/test-batch/route.js
+++ b/src/app/api/providers/test-batch/route.js
@@ -8,6 +8,7 @@ import {
   ANTHROPIC_COMPATIBLE_PREFIX,
 } from "@/shared/constants/providers";
 import { testSingleConnection } from "../[id]/test/testUtils.js";
+import { getProviderConnectionAccess } from "@/lib/providers/connectionAccess";
 
 function getAuthGroup(providerId, connection = null) {
   // Prioritize authType from connection if available
@@ -42,6 +43,7 @@ function isCompatibleProvider(providerId) {
 // POST /api/providers/test-batch - Test multiple connections by group
 export async function POST(request) {
   try {
+    const { ownerId } = await getProviderConnectionAccess();
     const body = await request.json();
     const { mode, providerId } = body;
 
@@ -49,7 +51,10 @@ export async function POST(request) {
       return NextResponse.json({ error: "mode is required" }, { status: 400 });
     }
 
-    const allConnections = await getProviderConnections({ isActive: true });
+    const allConnections = await getProviderConnections({
+      isActive: true,
+      ...(ownerId ? { ownerId } : {}),
+    });
 
     let connectionsToTest = [];
     if (mode === "provider" && providerId) {
@@ -125,6 +130,9 @@ export async function POST(request) {
       },
     });
   } catch (error) {
+    if (error.message === "Unauthorized") {
+      return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
+    }
     console.log("Error in batch test:", error);
     return NextResponse.json({ error: "Batch test failed" }, { status: 500 });
   }
diff --git a/src/lib/db/index.js b/src/lib/db/index.js
index ce08aaa1..a843de32 100644
--- a/src/lib/db/index.js
+++ b/src/lib/db/index.js
@@ -82,7 +82,7 @@ export async function exportDb() {
   const out = {
     settings: await exportSettings(),
     users: db.all(`SELECT id, username, password, role, isActive, createdAt, updatedAt FROM users`).map((r) => ({ ...r, isActive: r.isActive === 1 || r.isActive === true })),
-    providerConnections: db.all(`SELECT * FROM providerConnections`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, provider: r.provider, authType: r.authType, name: r.name, email: r.email, priority: r.priority, isActive: r.isActive === 1, createdAt: r.createdAt, updatedAt: r.updatedAt })),
+    providerConnections: db.all(`SELECT * FROM providerConnections`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, provider: r.provider, authType: r.authType, name: r.name, email: r.email, ownerId: r.ownerId, priority: r.priority, isActive: r.isActive === 1, createdAt: r.createdAt, updatedAt: r.updatedAt })),
     providerNodes: db.all(`SELECT * FROM providerNodes`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, type: r.type, name: r.name, createdAt: r.createdAt, updatedAt: r.updatedAt })),
     proxyPools: db.all(`SELECT * FROM proxyPools`).map((r) => ({ ...parseJson(r.data, {}), id: r.id, isActive: r.isActive === 1, testStatus: r.testStatus, createdAt: r.createdAt, updatedAt: r.updatedAt })),
     apiKeys: db.all(`SELECT * FROM apiKeys`).map((r) => ({ id: r.id, key: r.key, name: r.name, machineId: r.machineId, ownerId: r.ownerId, isActive: r.isActive === 1, createdAt: r.createdAt })),
@@ -144,11 +144,12 @@ export async function importDb(payload) {
       }
     }
 
+    const fallbackOwnerId = db.get(`SELECT id FROM users WHERE role = 'admin' ORDER BY createdAt ASC LIMIT 1`)?.id || null;
     for (const c of payload.providerConnections || []) {
-      const { id, provider, authType, name, email, priority, isActive, createdAt, updatedAt, ...rest } = c;
+      const { id, provider, authType, name, email, ownerId, priority, isActive, createdAt, updatedAt, ...rest } = c;
       db.run(
-        `INSERT OR REPLACE INTO providerConnections(id, provider, authType, name, email, priority, isActive, data, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
-        [id, provider, authType || "oauth", name || null, email || null, priority || null, isActive === false ? 0 : 1, stringifyJson(rest), createdAt || new Date().toISOString(), updatedAt || new Date().toISOString()]
+        `INSERT OR REPLACE INTO providerConnections(id, provider, authType, name, email, ownerId, priority, isActive, data, createdAt, updatedAt) VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)`,
+        [id, provider, authType || "oauth", name || null, email || null, ownerId || fallbackOwnerId, priority || null, isActive === false ? 0 : 1, stringifyJson(rest), createdAt || new Date().toISOString(), updatedAt || new Date().toISOString()]
       );
     }
     for (const n of payload.providerNodes || []) {
diff --git a/src/lib/db/migrations/004-provider-connection-owners.js b/src/lib/db/migrations/004-provider-connection-owners.js
new file mode 100644
index 00000000..620a87a5
--- /dev/null
+++ b/src/lib/db/migrations/004-provider-connection-owners.js
@@ -0,0 +1,20 @@
+// Provider connections belong to the dashboard account that created them.
+// Existing installations retain their connections under the first admin.
+export default {
+  version: 4,
+  name: "provider-connection-owners",
+  up(db) {
+    const columns = db.all(`PRAGMA table_info(providerConnections)`);
+    if (!columns.some((column) => column.name === "ownerId")) {
+      db.exec(`ALTER TABLE providerConnections ADD COLUMN ownerId TEXT`);
+    }
+
+    const admin = db.get(`SELECT id FROM users WHERE role = 'admin' ORDER BY createdAt ASC LIMIT 1`);
+    if (admin) {
+      db.run(
+        `UPDATE providerConnections SET ownerId = ? WHERE ownerId IS NULL OR ownerId = ''`,
+        [admin.id],
+      );
+    }
+  },
+};
\ No newline at end of file
diff --git a/src/lib/db/migrations/index.js b/src/lib/db/migrations/index.js
index 96a509a3..53a3c52c 100644
--- a/src/lib/db/migrations/index.js
+++ b/src/lib/db/migrations/index.js
@@ -4,8 +4,9 @@
 import m001 from "./001-initial.js";
 import m002 from "./002-users-table.js";
 import m003 from "./003-api-key-owners.js";
+import m004 from "./004-provider-connection-owners.js";
 
-export const MIGRATIONS = [m001, m002, m003].sort((a, b) => a.version - b.version);
+export const MIGRATIONS = [m001, m002, m003, m004].sort((a, b) => a.version - b.version);
 
 export function latestVersion() {
   return MIGRATIONS.length ? MIGRATIONS[MIGRATIONS.length - 1].version : 0;
diff --git a/src/lib/db/repos/connectionsRepo.js b/src/lib/db/repos/connectionsRepo.js
index 4181843f..beb0e8df 100644
--- a/src/lib/db/repos/connectionsRepo.js
+++ b/src/lib/db/repos/connectionsRepo.js
@@ -20,6 +20,7 @@ function rowToConn(row) {
     authType: row.authType,
     name: row.name,
     email: row.email,
+    ownerId: row.ownerId,
     priority: row.priority,
     isActive: row.isActive === 1 || row.isActive === true,
     createdAt: row.createdAt,
@@ -28,13 +29,14 @@ function rowToConn(row) {
 }
 
 function connToRow(c) {
-  const { id, provider, authType, name, email, priority, isActive, createdAt, updatedAt, ...rest } = c;
+  const { id, provider, authType, name, email, ownerId, priority, isActive, createdAt, updatedAt, ...rest } = c;
   return {
     id,
     provider,
     authType,
     name: name ?? null,
     email: email ?? null,
+    ownerId: ownerId ?? null,
     priority: priority ?? null,
     isActive: isActive === false ? 0 : 1,
     data: stringifyJson(rest),
@@ -46,13 +48,13 @@ function connToRow(c) {
 function upsert(db, c) {
   const r = connToRow(c);
   db.run(
-    `INSERT INTO providerConnections(id, provider, authType, name, email, priority, isActive, data, createdAt, updatedAt)
-     VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+    `INSERT INTO providerConnections(id, provider, authType, name, email, ownerId, priority, isActive, data, createdAt, updatedAt)
+     VALUES(?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
      ON CONFLICT(id) DO UPDATE SET
        provider=excluded.provider, authType=excluded.authType, name=excluded.name,
-       email=excluded.email, priority=excluded.priority, isActive=excluded.isActive,
+       email=excluded.email, ownerId=excluded.ownerId, priority=excluded.priority, isActive=excluded.isActive,
        data=excluded.data, updatedAt=excluded.updatedAt`,
-    [r.id, r.provider, r.authType, r.name, r.email, r.priority, r.isActive, r.data, r.createdAt, r.updatedAt]
+    [r.id, r.provider, r.authType, r.name, r.email, r.ownerId, r.priority, r.isActive, r.data, r.createdAt, r.updatedAt]
   );
 }
 
@@ -67,11 +69,54 @@ function deriveConnectionName(data, fallbackName) {
   return fallbackName;
 }
 
+function findDuplicateAccount(connections, data) {
+  const incomingCredential = data.accessToken || data.apiKey || data.refreshToken;
+  if (incomingCredential) {
+    const credentialMatch = connections.find((connection) => (
+      connection.accessToken === incomingCredential ||
+      connection.apiKey === incomingCredential ||
+      connection.refreshToken === incomingCredential
+    ));
+    if (credentialMatch) return credentialMatch;
+  }
+
+  if (!data.email) return null;
+
+  const incomingUsername = data.providerSpecificData?.username;
+  const incomingWorkspace = data.providerSpecificData?.chatgptAccountId;
+
+  return connections.find((connection) => {
+    if (connection.email !== data.email) return false;
+
+    const existingWorkspace = connection.providerSpecificData?.chatgptAccountId;
+    if (incomingWorkspace && existingWorkspace) {
+      return incomingWorkspace === existingWorkspace;
+    }
+    if (incomingWorkspace || existingWorkspace) return false;
+
+    const existingUsername = connection.providerSpecificData?.username;
+    if (incomingUsername && existingUsername) {
+      return incomingUsername === existingUsername;
+    }
+    if (incomingUsername || existingUsername) return false;
+
+    return true;
+  });
+}
+
+function duplicateAccountError() {
+  const error = new Error("Account already exists in the system");
+  error.code = "PROVIDER_ACCOUNT_EXISTS";
+  error.status = 409;
+  return error;
+}
+
 export async function getProviderConnections(filter = {}) {
   const db = await getAdapter();
   const where = [];
   const params = [];
   if (filter.provider) { where.push("provider = ?"); params.push(filter.provider); }
+  if (filter.ownerId) { where.push("ownerId = ?"); params.push(filter.ownerId); }
   if (filter.isActive !== undefined) { where.push("isActive = ?"); params.push(filter.isActive ? 1 : 0); }
   const sql = `SELECT * FROM providerConnections${where.length ? ` WHERE ${where.join(" AND ")}` : ""}`;
   const rows = db.all(sql, params);
@@ -80,9 +125,15 @@ export async function getProviderConnections(filter = {}) {
   return list;
 }
 
-export async function getProviderConnectionById(id) {
+export async function getProviderConnectionById(id, ownerId = null) {
   const db = await getAdapter();
-  const row = db.get(`SELECT * FROM providerConnections WHERE id = ?`, [id]);
+  const where = ["id = ?"];
+  const params = [id];
+  if (ownerId) {
+    where.push("ownerId = ?");
+    params.push(ownerId);
+  }
+  const row = db.get(`SELECT * FROM providerConnections WHERE ${where.join(" AND ")}`, params);
   return rowToConn(row);
 }
 
@@ -105,52 +156,17 @@ export async function createProviderConnection(data) {
   let result;
 
   db.transaction(() => {
-    const all = db.all(`SELECT * FROM providerConnections WHERE provider = ?`, [data.provider]).map(rowToConn);
+    const allProviderConnections = db.all(`SELECT * FROM providerConnections WHERE provider = ?`, [data.provider]).map(rowToConn);
+    const all = data.ownerId
+      ? allProviderConnections.filter((connection) => connection.ownerId === data.ownerId)
+      : allProviderConnections;
 
-    let existing = null;
-    if (data.authType === "oauth" && data.email) {
-      const incomingUsername = data.providerSpecificData?.username;
-      const incomingWs = data.providerSpecificData?.chatgptAccountId;
-      existing = all.find(c => {
-        if (c.authType !== "oauth" || c.email !== data.email) return false;
-
-        // Codex/OpenAI can issue multiple OAuth grants for the same email.
-        // Refresh tokens are rotated single-use; collapsing a new login onto an
-        // existing bare-email row overwrites the first account's token pair and
-        // makes it look "invalid" after adding a second account. Only update an
-        // existing Codex row when both rows expose the same ChatGPT account ID.
-        if (data.provider === "codex") {
-          const existingWs = c.providerSpecificData?.chatgptAccountId;
-          return !!incomingWs && !!existingWs && incomingWs === existingWs;
-        }
-
-        // Workspace providers use workspace ID when both sides have it
-        const existingWs = c.providerSpecificData?.chatgptAccountId;
-        if (incomingWs && existingWs) return incomingWs === existingWs;
-        if (incomingWs && !existingWs) return false;
-        if (!incomingWs && existingWs) return false;
-        // Non-workspace providers: match on (email + username) so cross-IdP
-        // accounts don't overwrite each other. Require username on both sides
-        // — if only one side has it, treat as a distinct identity rather than
-        // collapsing onto the bare-email fallback (which would re-introduce
-        // the cross-IdP overwrite).
-        const existingUsername = c.providerSpecificData?.username;
-        if (incomingUsername && existingUsername) {
-          return incomingUsername === existingUsername;
-        }
-        if (incomingUsername || existingUsername) return false;
-        return true;
-      });
-    } else if (data.authType === "apikey" && data.name) {
-      existing = all.find(c => c.authType === "apikey" && c.name === data.name);
-    }
-    // access_token: never dedup — user manages duplicates manually
-
-    if (existing) {
-      const merged = { ...existing, ...data, updatedAt: now };
-      upsert(db, merged);
-      result = merged;
-      return;
+    // Account identities are global: two dashboard users must not register the
+    // same provider account. API-key connections without an account identity
+    // or matching credential remain private and may use the same display name.
+    const existingAccount = findDuplicateAccount(allProviderConnections, data);
+    if (existingAccount) {
+      throw duplicateAccountError();
     }
 
     let connectionName = data.name || null;
@@ -167,6 +183,7 @@ export async function createProviderConnection(data) {
       provider: data.provider,
       authType: data.authType || "oauth",
       name: connectionName,
+      ownerId: data.ownerId || null,
       priority: connectionPriority,
       isActive: data.isActive !== undefined ? data.isActive : true,
       createdAt: now,
diff --git a/src/lib/db/schema.js b/src/lib/db/schema.js
index c197b577..785043db 100644
--- a/src/lib/db/schema.js
+++ b/src/lib/db/schema.js
@@ -3,7 +3,7 @@
 // pre-change safety backup in migrate.js: when the stored version is lower,
 // one lightweight DB backup is taken before applying schema changes. Forgetting
 // to bump only skips that backup — it does NOT break the additive auto-sync.
-export const SCHEMA_VERSION = 3;
+export const SCHEMA_VERSION = 4;
 
 export const PRAGMA_SQL = `
 PRAGMA journal_mode = WAL;
@@ -53,6 +53,7 @@ export const TABLES = {
       authType: "TEXT NOT NULL",
       name: "TEXT",
       email: "TEXT",
+      ownerId: "TEXT",
       priority: "INTEGER",
       isActive: "INTEGER DEFAULT 1",
       data: "TEXT NOT NULL",
@@ -61,6 +62,7 @@ export const TABLES = {
     },
     indexes: [
       "CREATE INDEX IF NOT EXISTS idx_pc_provider ON providerConnections(provider)",
+      "CREATE INDEX IF NOT EXISTS idx_pc_owner ON providerConnections(ownerId)",
       "CREATE INDEX IF NOT EXISTS idx_pc_provider_active ON providerConnections(provider, isActive)",
       "CREATE INDEX IF NOT EXISTS idx_pc_priority ON providerConnections(provider, priority)",
     ],
diff --git a/src/lib/oauth/utils/server.js b/src/lib/oauth/utils/server.js
index b11a9a44..6ef44385 100644
--- a/src/lib/oauth/utils/server.js
+++ b/src/lib/oauth/utils/server.js
@@ -129,11 +129,12 @@ const pendingExchanges = new Map();
  * Register a pending exchange session for server-side mode.
  * Modal client calls this before opening popup.
  */
-export function registerCodexSession({ state, codeVerifier, redirectUri }) {
-  if (!state || !codeVerifier || !redirectUri) return false;
+export function registerCodexSession({ state, codeVerifier, redirectUri, ownerId }) {
+  if (!state || !codeVerifier || !redirectUri || !ownerId) return false;
   pendingExchanges.set(state, {
     codeVerifier,
     redirectUri,
+    ownerId,
     status: "pending",
     createdAt: Date.now(),
   });
@@ -224,6 +225,7 @@ export function startCodexProxy(appPort) {
           const connection = await createProviderConnection({
             provider: "codex",
             authType: "oauth",
+            ownerId: session.ownerId,
             ...tokenData,
             expiresAt: tokenData.expiresIn
               ? new Date(Date.now() + tokenData.expiresIn * 1000).toISOString()
@@ -297,11 +299,12 @@ const XAI_PROXY_TIMEOUT_MS = 300000; // 5 minutes
 const XAI_PROXY_PORT = 56121;
 const xaiPendingExchanges = new Map();
 
-export function registerXaiSession({ state, codeVerifier, redirectUri }) {
-  if (!state || !codeVerifier || !redirectUri) return false;
+export function registerXaiSession({ state, codeVerifier, redirectUri, ownerId }) {
+  if (!state || !codeVerifier || !redirectUri || !ownerId) return false;
   xaiPendingExchanges.set(state, {
     codeVerifier,
     redirectUri,
+    ownerId,
     status: "pending",
     createdAt: Date.now(),
   });
@@ -366,6 +369,7 @@ export function startXaiProxy(appPort) {
           const connection = await createProviderConnection({
             provider: "xai",
             authType: "oauth",
+            ownerId: session.ownerId,
             ...tokenData,
             expiresAt: tokenData.expiresIn
               ? new Date(Date.now() + tokenData.expiresIn * 1000).toISOString()
diff --git a/src/lib/providers/connectionAccess.js b/src/lib/providers/connectionAccess.js
new file mode 100644
index 00000000..ea1ce3e3
--- /dev/null
+++ b/src/lib/providers/connectionAccess.js
@@ -0,0 +1,9 @@
+import { requireCurrentDashboardUser } from "@/lib/auth/currentUser";
+
+export async function getProviderConnectionAccess() {
+  const user = await requireCurrentDashboardUser();
+  return {
+    user,
+    ownerId: user.role === "admin" ? null : user.id,
+  };
+}
diff --git a/src/shared/components/OAuthModal.js b/src/shared/components/OAuthModal.js
index 6d7b2bba..bc2b246b 100644
--- a/src/shared/components/OAuthModal.js
+++ b/src/shared/components/OAuthModal.js
@@ -130,6 +130,10 @@ export default function OAuthModal({ isOpen, provider, providerInfo, onSuccess,
           return;
         }
 
+        if (!res.ok) {
+          throw new Error(data.error || "OAuth connection failed");
+        }
+
         if (data.error === "expired_token" || data.error === "access_denied") {
           throw new Error(data.errorDescription || data.error);
         }
diff --git a/tests/unit/db-migration-chain.test.js b/tests/unit/db-migration-chain.test.js
index 4a0a4c51..b4393afa 100644
--- a/tests/unit/db-migration-chain.test.js
+++ b/tests/unit/db-migration-chain.test.js
@@ -37,6 +37,8 @@ describe("Schema migrations", () => {
       "_meta", "settings", "providerConnections", "providerNodes",
       "proxyPools", "apiKeys", "combos", "kv", "usageHistory", "usageDaily", "requestDetails",
     ]));
+    expect(db.all(`PRAGMA table_info(providerConnections)`).map((column) => column.name)).toContain("ownerId");
+    expect(db.all(`PRAGMA index_list(providerConnections)`).map((index) => index.name)).toContain("idx_pc_owner");
   });
 
   it("existing DB at older schemaVersion → re-applies pending migrations on restart", async () => {
diff --git a/tests/unit/db-sqlite-vs-lowdb.test.js b/tests/unit/db-sqlite-vs-lowdb.test.js
index 68e4df6c..ba8ddba6 100644
--- a/tests/unit/db-sqlite-vs-lowdb.test.js
+++ b/tests/unit/db-sqlite-vs-lowdb.test.js
@@ -113,6 +113,86 @@ describe("DB SQLite layer — public API parity", () => {
     expect(back.providerSpecificData).toEqual({ foo: "bar" });
   });
 
+  it("providerConnections: scopes retrieval and lookup to connection owner", async () => {
+    const ownerOne = await sqliteDb.createUser({ username: "connection-owner-one", password: "password", role: "user" });
+    const ownerTwo = await sqliteDb.createUser({ username: "connection-owner-two", password: "password", role: "user" });
+    const firstConnection = await sqliteDb.createProviderConnection({
+      provider: "owner-test-one",
+      authType: "apikey",
+      name: "owner-one-connection",
+      apiKey: "key-one",
+      ownerId: ownerOne.id,
+    });
+    const secondConnection = await sqliteDb.createProviderConnection({
+      provider: "owner-test-two",
+      authType: "apikey",
+      name: "owner-two-connection",
+      apiKey: "key-two",
+      ownerId: ownerTwo.id,
+    });
+    const account = await sqliteDb.createProviderConnection({
+      provider: "owner-test-account",
+      authType: "oauth",
+      email: "shared@example.com",
+      accessToken: "token-one",
+      ownerId: ownerOne.id,
+    });
+
+    const ownerOneConnections = await sqliteDb.getProviderConnections({ ownerId: ownerOne.id });
+    expect(ownerOneConnections.map((connection) => connection.id)).toContain(firstConnection.id);
+    expect(ownerOneConnections.map((connection) => connection.id)).not.toContain(secondConnection.id);
+    await expect(sqliteDb.createProviderConnection({
+      provider: "owner-test-account",
+      authType: "oauth",
+      email: "shared@example.com",
+      accessToken: "token-two",
+      ownerId: ownerTwo.id,
+    })).rejects.toMatchObject({
+      code: "PROVIDER_ACCOUNT_EXISTS",
+      status: 409,
+    });
+    expect(account.ownerId).toBe(ownerOne.id);
+
+    await sqliteDb.createProviderConnection({
+      provider: "owner-test-token",
+      authType: "access_token",
+      accessToken: "shared-token",
+      ownerId: ownerOne.id,
+    });
+    await expect(sqliteDb.createProviderConnection({
+      provider: "owner-test-token",
+      authType: "access_token",
+      accessToken: "shared-token",
+      ownerId: ownerTwo.id,
+    })).rejects.toMatchObject({
+      code: "PROVIDER_ACCOUNT_EXISTS",
+      status: 409,
+    });
+
+    await sqliteDb.createProviderConnection({
+      provider: "owner-test-api-key",
+      authType: "apikey",
+      name: "first-key-name",
+      apiKey: "shared-api-key",
+      ownerId: ownerOne.id,
+    });
+    await expect(sqliteDb.createProviderConnection({
+      provider: "owner-test-api-key",
+      authType: "apikey",
+      name: "different-key-name",
+      apiKey: "shared-api-key",
+      ownerId: ownerTwo.id,
+    })).rejects.toMatchObject({
+      code: "PROVIDER_ACCOUNT_EXISTS",
+      status: 409,
+    });
+    expect(await sqliteDb.getProviderConnectionById(firstConnection.id, ownerTwo.id)).toBeNull();
+    expect(await sqliteDb.getProviderConnectionById(firstConnection.id, ownerOne.id)).toMatchObject({
+      id: firstConnection.id,
+      ownerId: ownerOne.id,
+    });
+  });
+
   it("providerConnections: GitHub OAuth uses account identity as fallback name", async () => {
     const c = await sqliteDb.createProviderConnection({
       provider: "github",