diff --git a/server/src/__tests__/invite-join-grants.test.ts b/server/src/__tests__/invite-join-grants.test.ts
index 0b3becaffc9..fae007e059d 100644
--- a/server/src/__tests__/invite-join-grants.test.ts
+++ b/server/src/__tests__/invite-join-grants.test.ts
@@ -1,5 +1,8 @@
 import { describe, expect, it } from "vitest";
-import { agentJoinGrantsFromDefaults } from "../services/invite-grants.js";
+import {
+  agentJoinGrantsFromDefaults,
+  humanJoinGrantsFromDefaults,
+} from "../services/invite-grants.js";
 import {
   grantsForHumanRole,
   normalizeHumanRole,
@@ -86,4 +89,33 @@ describe("human invite roles", () => {
       }),
     ).toBe("viewer");
   });
+
+  it("falls back to role grants when human invite defaults omit explicit grants", () => {
+    expect(humanJoinGrantsFromDefaults(null, "operator")).toEqual([
+      { permissionKey: "tasks:assign", scope: null },
+    ]);
+  });
+
+  it("preserves explicit human invite grants", () => {
+    expect(
+      humanJoinGrantsFromDefaults(
+        {
+          human: {
+            grants: [
+              {
+                permissionKey: "users:invite",
+                scope: { companyId: "company-1" },
+              },
+            ],
+          },
+        },
+        "operator",
+      ),
+    ).toEqual([
+      {
+        permissionKey: "users:invite",
+        scope: { companyId: "company-1" },
+      },
+    ]);
+  });
 });
diff --git a/server/src/routes/access.ts b/server/src/routes/access.ts
index ee4f6b5ac2e..c86637caf04 100644
--- a/server/src/routes/access.ts
+++ b/server/src/routes/access.ts
@@ -61,6 +61,7 @@ import {
   normalizeHumanRole,
   resolveHumanInviteRole,
 } from "../services/company-member-roles.js";
+import { humanJoinGrantsFromDefaults } from "../services/invite-grants.js";
 import {
   collapseDuplicatePendingHumanJoinRequests,
   findReusableHumanJoinRequest,
@@ -3359,9 +3360,9 @@ export function accessRoutes(
           membershipRole,
           "active"
         );
-        const grants = grantsFromDefaults(
+        const grants = humanJoinGrantsFromDefaults(
           invite.defaultsPayload as Record<string, unknown> | null,
-          "human"
+          membershipRole
         );
         await access.setPrincipalGrants(
           companyId,
diff --git a/server/src/services/invite-grants.ts b/server/src/services/invite-grants.ts
index e31d910fb8c..32c9aa42fe1 100644
--- a/server/src/services/invite-grants.ts
+++ b/server/src/services/invite-grants.ts
@@ -1,4 +1,6 @@
 import { PERMISSION_KEYS } from "@paperclipai/shared";
+import type { HumanCompanyMembershipRole } from "@paperclipai/shared";
+import { grantsForHumanRole } from "./company-member-roles.js";
 
 export function grantsFromDefaults(
   defaultsPayload: Record<string, unknown> | null | undefined,
@@ -53,3 +55,14 @@ export function agentJoinGrantsFromDefaults(
     },
   ];
 }
+
+export function humanJoinGrantsFromDefaults(
+  defaultsPayload: Record<string, unknown> | null | undefined,
+  membershipRole: HumanCompanyMembershipRole
+): Array<{
+  permissionKey: (typeof PERMISSION_KEYS)[number];
+  scope: Record<string, unknown> | null;
+}> {
+  const grants = grantsFromDefaults(defaultsPayload, "human");
+  return grants.length > 0 ? grants : grantsForHumanRole(membershipRole);
+}