diff --git a/.changeset/invitation-accept-url-console-base.md b/.changeset/invitation-accept-url-console-base.md
new file mode 100644
index 000000000..4e6c71027
--- /dev/null
+++ b/.changeset/invitation-accept-url-console-base.md
@@ -0,0 +1,27 @@
+---
+"@objectstack/plugin-auth": patch
+---
+
+fix(auth): invitation accept link is now an absolute URL under the Console base
+
+`sendInvitationEmail` built the accept URL straight from `config.baseUrl` with
+no scheme guarantee and no UI mount prefix — `${baseUrl}/accept-invitation/<id>`.
+Two problems surfaced in real deployments:
+
+1. When `baseUrl` was a bare host (e.g. `cloud.objectos.ai`, no scheme), the
+   emailed link was relative-looking; email clients would not linkify it and
+   clicking it went nowhere.
+2. The accept-invitation page is a Console SPA route mounted under `uiBasePath`
+   (default `/_console`) — the same router/basename as `/login`, `/register`
+   and `/oauth/consent`, and the exact link the Console itself generates for its
+   "copy invitation link" action (`${origin}${BASE_URL}accept-invitation/<id>`).
+   The root-path link omitted that prefix, so it 404'd at the host root instead
+   of resolving to the page.
+
+The link is now built as
+`${origin}${uiBasePath}/accept-invitation/<id>` via a hardened
+`getCanonicalOrigin()` that guarantees an absolute origin (prepends `https://`
+when `baseUrl` has no scheme). The scheme hardening also applies to the OAuth
+issuer / consent / device-flow URLs that share the helper. Deployments that
+mount the Console elsewhere are honoured through the existing `uiBasePath`
+config.
diff --git a/packages/plugins/plugin-auth/src/auth-manager.test.ts b/packages/plugins/plugin-auth/src/auth-manager.test.ts
index ba1adb12c..64ad82fc9 100644
--- a/packages/plugins/plugin-auth/src/auth-manager.test.ts
+++ b/packages/plugins/plugin-auth/src/auth-manager.test.ts
@@ -1342,6 +1342,53 @@ describe('AuthManager', () => {
       const { capturedConfig } = await boot({ plugins: { magicLink: true } });
       expect(capturedConfig.plugins.find((p: any) => p.id === 'magic-link')).toBeDefined();
     });
+
+    // The emailed accept URL must be an absolute link pointing at the Console
+    // SPA route, which is mounted under `uiBasePath` (default `/_console`) —
+    // the same basename as /login. A bare host in baseUrl (no scheme) also
+    // produced relative-looking links email clients wouldn't open.
+    it('sendInvitationEmail builds an absolute https:// accept URL under the Console base', async () => {
+      const { capturedConfig, emailService } = await boot({ baseUrl: 'cloud.objectos.ai' });
+      const orgPlugin = capturedConfig.plugins.find((p: any) => p.id === 'organization');
+      await orgPlugin._opts.sendInvitationEmail({
+        email: 'invitee@example.com',
+        invitation: { id: 'tok123', organizationId: 'o1', role: 'member' },
+        organization: { name: 'Org' },
+        inviter: { user: { email: 'admin@example.com' } },
+      });
+      expect(emailService.sendTemplate).toHaveBeenCalledTimes(1);
+      const { data } = emailService.sendTemplate.mock.calls[0][0];
+      expect(data.acceptUrl).toBe('https://cloud.objectos.ai/_console/accept-invitation/tok123');
+    });
+
+    it('sendInvitationEmail preserves an explicit scheme in baseUrl', async () => {
+      const { capturedConfig, emailService } = await boot({ baseUrl: 'http://localhost:3000/' });
+      const orgPlugin = capturedConfig.plugins.find((p: any) => p.id === 'organization');
+      await orgPlugin._opts.sendInvitationEmail({
+        email: 'invitee@example.com',
+        invitation: { id: 'tok456', organizationId: 'o1', role: 'member' },
+        organization: { name: 'Org' },
+        inviter: { user: { email: 'admin@example.com' } },
+      });
+      const { data } = emailService.sendTemplate.mock.calls[0][0];
+      expect(data.acceptUrl).toBe('http://localhost:3000/_console/accept-invitation/tok456');
+    });
+
+    it('sendInvitationEmail honours a custom uiBasePath (Console mounted elsewhere)', async () => {
+      const { capturedConfig, emailService } = await boot({
+        baseUrl: 'https://acme.example.com',
+        uiBasePath: '/console/',
+      });
+      const orgPlugin = capturedConfig.plugins.find((p: any) => p.id === 'organization');
+      await orgPlugin._opts.sendInvitationEmail({
+        email: 'invitee@example.com',
+        invitation: { id: 'tok789', organizationId: 'o1', role: 'member' },
+        organization: { name: 'Org' },
+        inviter: { user: { email: 'admin@example.com' } },
+      });
+      const { data } = emailService.sendTemplate.mock.calls[0][0];
+      expect(data.acceptUrl).toBe('https://acme.example.com/console/accept-invitation/tok789');
+    });
   });
 
   describe('getPublicConfig', () => {
diff --git a/packages/plugins/plugin-auth/src/auth-manager.ts b/packages/plugins/plugin-auth/src/auth-manager.ts
index 5e496f5d1..19524427c 100644
--- a/packages/plugins/plugin-auth/src/auth-manager.ts
+++ b/packages/plugins/plugin-auth/src/auth-manager.ts
@@ -1513,8 +1513,15 @@ export class AuthManager {
         // operators / UI can fall back to copy-paste flows. Replace this
         // with a real mail integration when available.
         sendInvitationEmail: async ({ email: recipientEmail, invitation, organization: org, inviter }) => {
-          const baseUrl = (this.config.baseUrl ?? '').replace(/\/$/, '');
-          const acceptUrl = `${baseUrl}/accept-invitation/${invitation.id}`;
+          // The accept-invitation page is a Console SPA route mounted under
+          // `uiBasePath` (default `/_console`) — the SAME router/basename as
+          // /login, /register and /oauth/consent. The Console builds the very
+          // same link for its "copy invitation link" action
+          // (`${origin}${BASE_URL}accept-invitation/<id>`), so the emailed link
+          // MUST carry that prefix (and an absolute https origin) or it 404s at
+          // the host root instead of resolving to the page.
+          const uiBase = (this.config.uiBasePath ?? '/_console').replace(/\/$/, '');
+          const acceptUrl = `${this.getCanonicalOrigin()}${uiBase}/accept-invitation/${invitation.id}`;
           // #2766 V1.5 — placeholder addresses are never real recipients.
           if (isPlaceholderEmail(recipientEmail)) {
             throw new Error(
@@ -2360,7 +2367,12 @@ export class AuthManager {
 
   /** Canonical origin of this deployment (config `baseUrl`, auto-detected in dev). */
   private getCanonicalOrigin(): string {
-    return (this.config.baseUrl || 'http://localhost:3000').replace(/\/$/, '');
+    const raw = (this.config.baseUrl || 'http://localhost:3000').trim().replace(/\/$/, '');
+    // Guarantee an absolute origin with a scheme. A bare host (e.g. baseUrl
+    // configured as `cloud.objectos.ai`) yields relative-looking links that
+    // email clients won't linkify and that break when clicked — prepend
+    // https:// so invitation / OAuth URLs open correctly.
+    return /^https?:\/\//i.test(raw) ? raw : `https://${raw}`;
   }
 
   /**