diff --git a/lib/permissions/minimally-encoded-raw-thread-info-validators.js b/lib/permissions/minimally-encoded-raw-thread-info-validators.js
--- a/lib/permissions/minimally-encoded-raw-thread-info-validators.js
+++ b/lib/permissions/minimally-encoded-raw-thread-info-validators.js
@@ -17,7 +17,6 @@
   type LegacyRawThreadInfo,
   legacyMemberInfoValidator,
   legacyRawThreadInfoValidator,
-  clientLegacyRoleInfoValidator,
   legacyThreadCurrentUserInfoValidator,
 } from '../types/thread-types.js';
 import { tBool, tID, tShape } from '../utils/validation-utils.js';
@@ -30,7 +29,8 @@
   });
 
 const roleInfoValidator: TInterface<RoleInfo> = tShape<RoleInfo>({
-  ...clientLegacyRoleInfoValidator.meta.props,
+  id: tID,
+  name: t.String,
   minimallyEncoded: tBool(true),
   permissions: t.list(tHexEncodedRolePermission),
   specialRole: t.maybe(specialRoleValidator),
diff --git a/lib/permissions/minimally-encoded-thread-permissions-test-data.js b/lib/permissions/minimally-encoded-thread-permissions-test-data.js
--- a/lib/permissions/minimally-encoded-thread-permissions-test-data.js
+++ b/lib/permissions/minimally-encoded-thread-permissions-test-data.js
@@ -351,7 +351,6 @@
         '015',
         '0a9',
       ],
-      isDefault: true,
     },
   },
   currentUser: {
diff --git a/lib/permissions/minimally-encoded-thread-permissions.test.js b/lib/permissions/minimally-encoded-thread-permissions.test.js
--- a/lib/permissions/minimally-encoded-thread-permissions.test.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.test.js
@@ -347,7 +347,6 @@
         id: 'roleID',
         name: 'roleName',
         permissions: ['abc', 'def'],
-        isDefault: true,
         specialRole: specialRoles.DEFAULT_ROLE,
       }),
     ).toBe(true);
diff --git a/lib/permissions/special-roles.test.js b/lib/permissions/special-roles.test.js
--- a/lib/permissions/special-roles.test.js
+++ b/lib/permissions/special-roles.test.js
@@ -16,7 +16,7 @@
       id: 'roleID',
       name: 'roleName',
       permissions: ['abc', 'def'],
-      isDefault: true,
+      specialRole: specialRoles.DEFAULT_ROLE,
     };
     const patchedRole = patchRoleInfoWithSpecialRole(role);
     expect(patchedRole.specialRole).toBe(specialRoles.DEFAULT_ROLE);
@@ -28,7 +28,6 @@
       id: 'roleID',
       name: 'Admins',
       permissions: ['abc', 'def'],
-      isDefault: false,
     };
     const patchedRole = patchRoleInfoWithSpecialRole(role);
     expect(patchedRole.specialRole).toBe(specialRoles.ADMIN_ROLE);
@@ -40,7 +39,6 @@
       id: 'roleID',
       name: 'BLAH',
       permissions: ['abc', 'def'],
-      isDefault: false,
     };
     const patchedRole = patchRoleInfoWithSpecialRole(role);
     expect(patchedRole.specialRole).toBe(undefined);
@@ -81,8 +79,8 @@
         id: '256|83795',
         name: 'Members',
         permissions: ['000', '010', '005', '015', '0a7'],
-        isDefault: true,
         minimallyEncoded: true,
+        specialRole: specialRoles.DEFAULT_ROLE,
       },
       '256|83796': {
         id: '256|83796',
@@ -127,7 +125,6 @@
           '134',
           '156',
         ],
-        isDefault: false,
         minimallyEncoded: true,
       },
     },
@@ -192,7 +189,6 @@
           '015',
           '0a9',
         ],
-        isDefault: false,
         minimallyEncoded: true,
       },
     },
diff --git a/lib/reducers/calendar-filters-reducer.test.js b/lib/reducers/calendar-filters-reducer.test.js
--- a/lib/reducers/calendar-filters-reducer.test.js
+++ b/lib/reducers/calendar-filters-reducer.test.js
@@ -48,14 +48,12 @@
           id: '256|83795',
           name: 'Members',
           permissions: ['000', '010', '005', '015', '0a7'],
-          isDefault: true,
           minimallyEncoded: true,
         },
         '256|83796': {
           id: '256|83796',
           name: 'Admins',
           permissions: ['000', '010', '005', '015', '0a7'],
-          isDefault: false,
           minimallyEncoded: true,
         },
       },
@@ -105,7 +103,6 @@
           id: '256|83816',
           name: 'Members',
           permissions: ['000', '010', '005', '015', '0a7'],
-          isDefault: true,
           minimallyEncoded: true,
         },
       },
diff --git a/lib/shared/thread-utils.test.js b/lib/shared/thread-utils.test.js
--- a/lib/shared/thread-utils.test.js
+++ b/lib/shared/thread-utils.test.js
@@ -107,7 +107,6 @@
       id: '83795',
       name: 'Members',
       permissions: ['000', '010', '005', '015', '0a7'],
-      isDefault: true,
       minimallyEncoded: true,
     },
     '83796': {
@@ -153,7 +152,6 @@
         '134',
         '156',
       ],
-      isDefault: false,
       minimallyEncoded: true,
     },
   },
diff --git a/lib/types/minimally-encoded-thread-permissions-types.js b/lib/types/minimally-encoded-thread-permissions-types.js
--- a/lib/types/minimally-encoded-thread-permissions-types.js
+++ b/lib/types/minimally-encoded-thread-permissions-types.js
@@ -18,10 +18,13 @@
   threadRolePermissionsBlobToBitmaskArray,
 } from '../permissions/minimally-encoded-thread-permissions.js';
 import type { SpecialRole } from '../permissions/special-roles.js';
+import { specialRoles } from '../permissions/special-roles.js';
+import { roleIsAdminRole, roleIsDefaultRole } from '../shared/thread-utils.js';
 import type { ThreadEntity } from '../utils/entity-text.js';
 
 export type RoleInfo = $ReadOnly<{
-  ...ClientLegacyRoleInfo,
+  +id: string,
+  +name: string,
   +minimallyEncoded: true,
   +permissions: $ReadOnlyArray<string>,
   +specialRole?: ?SpecialRole,
@@ -32,10 +35,18 @@
     !('minimallyEncoded' in roleInfo),
     'roleInfo is already minimally encoded.',
   );
+  let specialRole: ?SpecialRole;
+  if (roleIsDefaultRole(roleInfo)) {
+    specialRole = specialRoles.DEFAULT_ROLE;
+  } else if (roleIsAdminRole(roleInfo)) {
+    specialRole = specialRoles.ADMIN_ROLE;
+  }
+  const { isDefault, ...rest } = roleInfo;
   return {
-    ...roleInfo,
+    ...rest,
     minimallyEncoded: true,
     permissions: threadRolePermissionsBlobToBitmaskArray(roleInfo.permissions),
+    specialRole,
   };
 };
 
@@ -48,6 +59,7 @@
     permissions: decodeThreadRolePermissionsBitmaskArray(
       minimallyEncodedRoleInfo.permissions,
     ),
+    isDefault: roleIsDefaultRole(minimallyEncodedRoleInfo),
   };
 };