From 643a3eee8554410a908414a76d92f8f20b9181a5 Mon Sep 17 00:00:00 2001
From: John Brunton <john_brunton@live.co.uk>
Date: Sat, 24 Aug 2024 15:05:33 +0100
Subject: [PATCH] feat: invite users (#145)

---
 client/src/data/messages.ts                   |   1 +
 .../src/features/room/organisms/ChatBox.tsx   |   6 +-
 services/api/.eslintrc.js                     |   2 +-
 services/api/package-lock.json                | 283 ++++++++++--------
 services/api/package.json                     |   6 +-
 .../src/app/auth/permissions/roles.spec.ts    |  55 +++-
 .../api/src/app/auth/permissions/roles.ts     |  29 +-
 .../api/src/app/messages/command.service.ts   |  51 ++--
 .../api/src/app/messages/messages.module.ts   |   4 +
 services/api/src/app/users/users.service.ts   |  17 +-
 services/api/src/data/adapters/schema.ts      |   2 +
 .../dynamodb.users.repository.e2e-spec.ts     |  39 +--
 .../repositories/dynamodb.users.repository.ts |  16 +-
 .../src/domain/entities/membership.entity.ts  |  34 +++
 .../domain/entities/memberships.repository.ts |   1 +
 .../api/src/domain/entities/users/system.ts   |   4 +-
 .../src/domain/entities/users/user.entity.ts  |   1 +
 .../domain/entities/users/users.repository.ts |  19 +-
 .../src/domain/usecases/commands/help.spec.ts |   2 +
 .../usecases/commands/parse/command.parser.ts |   2 +
 .../usecases/commands/parse/parse.spec.ts     |  71 +++++
 .../usecases/commands/parse/parsers/index.ts  |   4 +
 .../commands/parse/parsers/invite-parser.ts   |  16 +
 .../commands/parse/parsers/leave.parser.ts    |  14 +
 .../src/domain/usecases/rooms/invite.spec.ts  | 148 +++++++++
 .../api/src/domain/usecases/rooms/invite.ts   |  95 ++++++
 .../src/domain/usecases/rooms/leave.spec.ts   |  59 ++++
 .../api/src/domain/usecases/rooms/leave.ts    |  43 +++
 services/api/src/fixtures/auth/FakeAuth.ts    |   1 +
 .../src/fixtures/auth/auth-info.factory.ts    |   1 +
 .../fixtures/data/test.users.repository.ts    |   8 +
 .../api/src/fixtures/messages/user.factory.ts |   1 +
 32 files changed, 837 insertions(+), 198 deletions(-)
 create mode 100644 services/api/src/domain/usecases/commands/parse/parsers/invite-parser.ts
 create mode 100644 services/api/src/domain/usecases/commands/parse/parsers/leave.parser.ts
 create mode 100644 services/api/src/domain/usecases/rooms/invite.spec.ts
 create mode 100644 services/api/src/domain/usecases/rooms/invite.ts
 create mode 100644 services/api/src/domain/usecases/rooms/leave.spec.ts
 create mode 100644 services/api/src/domain/usecases/rooms/leave.ts

diff --git a/client/src/data/messages.ts b/client/src/data/messages.ts
index 586cd8d1..cb83dd49 100644
--- a/client/src/data/messages.ts
+++ b/client/src/data/messages.ts
@@ -55,6 +55,7 @@ export const useMessagesSubscription = (roomId?: string, opts: QueryOptions = De
       }
       if (message.updatedEntities?.includes('users')) {
         queryClient.invalidateQueries({ queryKey: ['users'] })
+        queryClient.invalidateQueries({ queryKey: ['me'] })
       }
       queryClient.setQueryData(['messages', message.roomId], (messages: Message[] | undefined) => {
         if (!messages) return
diff --git a/client/src/features/room/organisms/ChatBox.tsx b/client/src/features/room/organisms/ChatBox.tsx
index 2c398024..7dfbab64 100644
--- a/client/src/features/room/organisms/ChatBox.tsx
+++ b/client/src/features/room/organisms/ChatBox.tsx
@@ -1,5 +1,5 @@
 import { Button, Icon, Textarea, Spinner, VStack, Alert, AlertIcon, Spacer } from '@chakra-ui/react'
-import React, { useState, KeyboardEventHandler, useRef, useEffect } from 'react'
+import React, { useState, KeyboardEventHandler, useRef, useEffect, ReactElement } from 'react'
 import { AiOutlineArrowRight } from 'react-icons/ai'
 import { usePostMessage } from '../../../data/messages'
 import { useJoinRoom } from '../../../data/rooms'
@@ -23,7 +23,7 @@ const JoinAlert = ({ roomId, canJoin }: ChatBoxProps) => {
     return (
       <Alert status='info' variant='top-accent'>
         <AlertIcon />
-        You need to join this room to chat.
+        Join this room to chat.
         <Spacer />
         <Button rightIcon={isLoading ? <Spinner /> : undefined} onClick={() => joinRoom()}>
           Join
@@ -40,7 +40,7 @@ const JoinAlert = ({ roomId, canJoin }: ChatBoxProps) => {
   )
 }
 
-export const ChatBox: React.FC<ChatBoxProps> = ({ roomId, canJoin }: ChatBoxProps) => {
+export const ChatBox: React.FC<ChatBoxProps> = ({ roomId, canJoin }: ChatBoxProps): ReactElement => {
   const [content, setContent] = useState<string>('')
   const { data: user, isLoading } = useUserDetails()
   const joined = user?.rooms.some((room) => room.id === roomId)
diff --git a/services/api/.eslintrc.js b/services/api/.eslintrc.js
index 3cd8928e..8745eef7 100644
--- a/services/api/.eslintrc.js
+++ b/services/api/.eslintrc.js
@@ -95,7 +95,7 @@ module.exports = {
           },
           {
             from: ['*'],
-            allow: ['rambda', 'rxjs', 'zod'],
+            allow: ['rambda', 'remeda', 'rxjs', 'zod'],
           },
         ],
       },
diff --git a/services/api/package-lock.json b/services/api/package-lock.json
index 1ca0a1d4..2dbe9a26 100644
--- a/services/api/package-lock.json
+++ b/services/api/package-lock.json
@@ -35,8 +35,10 @@
         "passport-jwt": "4.0.0",
         "rambda": "7.4.0",
         "reflect-metadata": "^0.1.13",
+        "remeda": "2.11.0",
         "rimraf": "^3.0.2",
         "rxjs": "^7.2.0",
+        "ts-pattern": "5.3.1",
         "zod": "3.21.4"
       },
       "devDependencies": {
@@ -63,7 +65,7 @@
         "http-server": "14.1.1",
         "jest": "29.7.0",
         "jest-fail-on-console": "3.1.1",
-        "jest-mock-extended": "3.0.1",
+        "jest-mock-extended": "3.0.7",
         "prettier": "^2.3.2",
         "source-map-support": "^0.5.20",
         "supertest": "^6.1.3",
@@ -72,7 +74,7 @@
         "ts-node": "^10.0.0",
         "tsconfig-paths": "4.1.0",
         "typedoc": "0.26.5",
-        "typescript": "^4.7.4"
+        "typescript": "^5.0.0"
       },
       "engines": {
         "node": "18.x"
@@ -3749,35 +3751,36 @@
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-      "resolved": "https://registry.npmjs.org/@nestjs/schematics/-/schematics-9.0.3.tgz",
-      "integrity": "sha512-kZrU/lrpVd2cnK8I3ibDb3Wi1ppl3wX3U3lVWoL+DzRRoezWKkh8upEL4q0koKmuXnsmLiu3UPxFeMOrJV7TSA==",
+      "version": "9.2.0",
+      "resolved": "https://registry.npmjs.org/@nestjs/schematics/-/schematics-9.2.0.tgz",
+      "integrity": "sha512-wHpNJDPzM6XtZUOB3gW0J6mkFCSJilzCM3XrHI1o0C8vZmFE1snbmkIXNyoi1eV0Nxh1BMymcgz5vIMJgQtTqw==",
       "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "@angular-devkit/core": "14.2.1",
-        "@angular-devkit/schematics": "14.2.1",
-        "fs-extra": "10.1.0",
+        "@angular-devkit/core": "16.0.1",
+        "@angular-devkit/schematics": "16.0.1",
         "jsonc-parser": "3.2.0",
         "pluralize": "8.0.0"
       },
       "peerDependencies": {
-        "typescript": "^4.3.5"
+        "typescript": ">=4.3.5"
       }
     },
     "node_modules/@nestjs/schematics/node_modules/@angular-devkit/core": {
-      "version": "14.2.1",
-      "resolved": "https://registry.npmjs.org/@angular-devkit/core/-/core-14.2.1.tgz",
-      "integrity": "sha512-lW8oNGuJqr4r31FWBjfWQYkSXdiOHBGOThIEtHvUVBKfPF/oVrupLueCUgBPel+NvxENXdo93uPsqHN7bZbmsQ==",
+      "version": "16.0.1",
+      "resolved": "https://registry.npmjs.org/@angular-devkit/core/-/core-16.0.1.tgz",
+      "integrity": "sha512-2uz98IqkKJlgnHbWQ7VeL4pb+snGAZXIama2KXi+k9GsRntdcw+udX8rL3G9SdUGUF+m6+147Y1oRBMHsO/v4w==",
       "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "ajv": "8.11.0",
+        "ajv": "8.12.0",
         "ajv-formats": "2.1.1",
-        "jsonc-parser": "3.1.0",
-        "rxjs": "6.6.7",
+        "jsonc-parser": "3.2.0",
+        "rxjs": "7.8.1",
         "source-map": "0.7.4"
       },
       "engines": {
-        "node": "^14.15.0 || >=16.10.0",
+        "node": "^16.14.0 || >=18.10.0",
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         "yarn": ">= 1.13.0"
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@@ -3790,60 +3793,62 @@
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     "node_modules/@nestjs/schematics/node_modules/@angular-devkit/schematics": {
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+      "version": "16.0.1",
+      "resolved": "https://registry.npmjs.org/@angular-devkit/schematics/-/schematics-16.0.1.tgz",
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       "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "@angular-devkit/core": "14.2.1",
-        "jsonc-parser": "3.1.0",
-        "magic-string": "0.26.2",
+        "@angular-devkit/core": "16.0.1",
+        "jsonc-parser": "3.2.0",
+        "magic-string": "0.30.0",
         "ora": "5.4.1",
-        "rxjs": "6.6.7"
+        "rxjs": "7.8.1"
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+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "fast-deep-equal": "^3.1.1",
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+      },
+      "funding": {
+        "type": "github",
+        "url": "https://github.com/sponsors/epoberezkin"
+      }
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-    "node_modules/@nestjs/schematics/node_modules/rxjs": {
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+    "node_modules/@nestjs/schematics/node_modules/magic-string": {
+      "version": "0.30.0",
+      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.0.tgz",
+      "integrity": "sha512-LA+31JYDJLs82r2ScLrlz1GjSgu66ZV518eyWT+S8VhyQn/JL0u9MeBOvQMGYiPk1DBiSN9DDMOcXvigJZaViQ==",
       "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "tslib": "^1.9.0"
+        "@jridgewell/sourcemap-codec": "^1.4.13"
       },
       "engines": {
-        "npm": ">=2.0.0"
+        "node": ">=12"
       }
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-    "node_modules/@nestjs/schematics/node_modules/tslib": {
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-      "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.14.1.tgz",
-      "integrity": "sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==",
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@@ -10128,16 +10133,17 @@
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+      "version": "3.0.7",
+      "resolved": "https://registry.npmjs.org/jest-mock-extended/-/jest-mock-extended-3.0.7.tgz",
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       "dev": true,
+      "license": "MIT",
       "dependencies": {
-        "ts-essentials": "^7.0.3"
+        "ts-essentials": "^10.0.0"
       },
       "peerDependencies": {
         "jest": "^24.0.0 || ^25.0.0 || ^26.0.0 || ^27.0.0 || ^28.0.0 || ^29.0.0",
-        "typescript": "^3.0.0 || ^4.0.0"
+        "typescript": "^3.0.0 || ^4.0.0 || ^5.0.0"
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     "node_modules/jest-mock/node_modules/chalk": {
@@ -12362,6 +12368,7 @@
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       "dev": true,
+      "license": "MIT",
       "engines": {
         "node": ">=4"
       }
@@ -12702,6 +12709,26 @@
         "url": "https://github.com/sponsors/mysticatea"
       }
     },
+    "node_modules/remeda": {
+      "version": "2.11.0",
+      "resolved": "https://registry.npmjs.org/remeda/-/remeda-2.11.0.tgz",
+      "integrity": "sha512-rQO+zcuNvnTcB2vBctblBARZakY0+wMNtrFGqU1+h4jm5p2APcDKQxUZG2CmMPkSQxa2nauU55GBVS/3Fo83fA==",
+      "dependencies": {
+        "type-fest": "^4.23.0"
+      }
+    },
+    "node_modules/remeda/node_modules/type-fest": {
+      "version": "4.25.0",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-4.25.0.tgz",
+      "integrity": "sha512-bRkIGlXsnGBRBQRAY56UXBm//9qH4bmJfFvq83gSz41N282df+fjy8ofcEgc1sM8geNt5cl6mC2g9Fht1cs8Aw==",
+      "license": "(MIT OR CC0-1.0)",
+      "engines": {
+        "node": ">=16"
+      },
+      "funding": {
+        "url": "https://github.com/sponsors/sindresorhus"
+      }
+    },
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@@ -13836,12 +13863,18 @@
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     "node_modules/ts-essentials": {
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-      "resolved": "https://registry.npmjs.org/ts-essentials/-/ts-essentials-7.0.3.tgz",
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+      "version": "10.0.2",
+      "resolved": "https://registry.npmjs.org/ts-essentials/-/ts-essentials-10.0.2.tgz",
+      "integrity": "sha512-Xwag0TULqriaugXqVdDiGZ5wuZpqABZlpwQ2Ho4GDyiu/R2Xjkp/9+zcFxL7uzeLl/QCPrflnvpVYyS3ouT7Zw==",
       "dev": true,
+      "license": "MIT",
       "peerDependencies": {
-        "typescript": ">=3.7.0"
+        "typescript": ">=4.5.0"
+      },
+      "peerDependenciesMeta": {
+        "typescript": {
+          "optional": true
+        }
       }
     },
     "node_modules/ts-jest": {
@@ -14015,6 +14048,12 @@
         }
       }
     },
+    "node_modules/ts-pattern": {
+      "version": "5.3.1",
+      "resolved": "https://registry.npmjs.org/ts-pattern/-/ts-pattern-5.3.1.tgz",
+      "integrity": "sha512-1RUMKa8jYQdNfmnK4jyzBK3/PS/tnjcZ1CW0v1vWDeYe5RBklc/nquw03MEoB66hVBm4BnlCfmOqDVxHyT1DpA==",
+      "license": "MIT"
+    },
     "node_modules/tsconfig-paths": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/tsconfig-paths/-/tsconfig-paths-4.1.0.tgz",
@@ -14246,16 +14285,17 @@
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+      "version": "5.5.4",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.4.tgz",
+      "integrity": "sha512-Mtq29sKDAEYP7aljRgtPOpTvOfbwRWlS6dPRzwjdE+C0R4brX/GUyhHSecbHMFLNBLcJIPt9nl9yG5TZ1weH+Q==",
       "dev": true,
+      "license": "Apache-2.0",
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
       },
       "engines": {
-        "node": ">=4.2.0"
+        "node": ">=14.17"
       }
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     "node_modules/uc.micro": {
@@ -17680,58 +17720,53 @@
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-        "@angular-devkit/core": "14.2.1",
-        "@angular-devkit/schematics": "14.2.1",
-        "fs-extra": "10.1.0",
+        "@angular-devkit/core": "16.0.1",
+        "@angular-devkit/schematics": "16.0.1",
         "jsonc-parser": "3.2.0",
         "pluralize": "8.0.0"
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-          "integrity": "sha512-lW8oNGuJqr4r31FWBjfWQYkSXdiOHBGOThIEtHvUVBKfPF/oVrupLueCUgBPel+NvxENXdo93uPsqHN7bZbmsQ==",
+          "version": "16.0.1",
+          "resolved": "https://registry.npmjs.org/@angular-devkit/core/-/core-16.0.1.tgz",
+          "integrity": "sha512-2uz98IqkKJlgnHbWQ7VeL4pb+snGAZXIama2KXi+k9GsRntdcw+udX8rL3G9SdUGUF+m6+147Y1oRBMHsO/v4w==",
           "dev": true,
           "requires": {
-            "ajv": "8.11.0",
+            "ajv": "8.12.0",
             "ajv-formats": "2.1.1",
-            "jsonc-parser": "3.1.0",
-            "rxjs": "6.6.7",
+            "jsonc-parser": "3.2.0",
+            "rxjs": "7.8.1",
             "source-map": "0.7.4"
-          },
-          "dependencies": {
-            "jsonc-parser": {
-              "version": "3.1.0",
-              "resolved": "https://registry.npmjs.org/jsonc-parser/-/jsonc-parser-3.1.0.tgz",
-              "integrity": "sha512-DRf0QjnNeCUds3xTjKlQQ3DpJD51GvDjJfnxUVWg6PZTo2otSm+slzNAxU/35hF8/oJIKoG9slq30JYOsF2azg==",
-              "dev": true
-            }
           }
         },
         "@angular-devkit/schematics": {
-          "version": "14.2.1",
-          "resolved": "https://registry.npmjs.org/@angular-devkit/schematics/-/schematics-14.2.1.tgz",
-          "integrity": "sha512-0U18FwDYt4zROBPrvewH6iBTkf2ozVHN4/gxUb9jWrqVw8mPU5AWc/iYxQLHBSinkr2Egjo1H/i9aBqgJSeh3g==",
+          "version": "16.0.1",
+          "resolved": "https://registry.npmjs.org/@angular-devkit/schematics/-/schematics-16.0.1.tgz",
+          "integrity": "sha512-A9D0LTYmiqiBa90GKcSuWb7hUouGIbm/AHbJbjL85WLLRbQA2PwKl7P5Mpd6nS/ZC0kfG4VQY3VOaDvb3qpI9g==",
           "dev": true,
           "requires": {
-            "@angular-devkit/core": "14.2.1",
-            "jsonc-parser": "3.1.0",
-            "magic-string": "0.26.2",
+            "@angular-devkit/core": "16.0.1",
+            "jsonc-parser": "3.2.0",
+            "magic-string": "0.30.0",
             "ora": "5.4.1",
-            "rxjs": "6.6.7"
-          },
-          "dependencies": {
-            "jsonc-parser": {
-              "version": "3.1.0",
-              "resolved": "https://registry.npmjs.org/jsonc-parser/-/jsonc-parser-3.1.0.tgz",
-              "integrity": "sha512-DRf0QjnNeCUds3xTjKlQQ3DpJD51GvDjJfnxUVWg6PZTo2otSm+slzNAxU/35hF8/oJIKoG9slq30JYOsF2azg==",
-              "dev": true
-            }
+            "rxjs": "7.8.1"
+          }
+        },
+        "ajv": {
+          "version": "8.12.0",
+          "resolved": "https://registry.npmjs.org/ajv/-/ajv-8.12.0.tgz",
+          "integrity": "sha512-sRu1kpcO9yLtYxBKvqfTeh9KzZEwO3STyX1HT+4CaDzC6HpTGYhIhPIzj9XuKU7KYDwnaeh5hcOwjy1QuJzBPA==",
+          "dev": true,
+          "requires": {
+            "fast-deep-equal": "^3.1.1",
+            "json-schema-traverse": "^1.0.0",
+            "require-from-string": "^2.0.2",
+            "uri-js": "^4.2.2"
           }
         },
         "jsonc-parser": {
@@ -17740,20 +17775,14 @@
           "integrity": "sha512-gfFQZrcTc8CnKXp6Y4/CBT3fTc0OVuDofpre4aEeEpSBPV5X5v4+Vmx+8snU7RLPrNHPKSgLxGo9YuQzz20o+w==",
           "dev": true
         },
-        "rxjs": {
-          "version": "6.6.7",
-          "resolved": "https://registry.npmjs.org/rxjs/-/rxjs-6.6.7.tgz",
-          "integrity": "sha512-hTdwr+7yYNIT5n4AMYp85KA6yw2Va0FLa3Rguvbpa4W3I5xynaBZo41cM3XM+4Q6fRMj3sBYIR1VAmZMXYJvRQ==",
+        "magic-string": {
+          "version": "0.30.0",
+          "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.0.tgz",
+          "integrity": "sha512-LA+31JYDJLs82r2ScLrlz1GjSgu66ZV518eyWT+S8VhyQn/JL0u9MeBOvQMGYiPk1DBiSN9DDMOcXvigJZaViQ==",
           "dev": true,
           "requires": {
-            "tslib": "^1.9.0"
+            "@jridgewell/sourcemap-codec": "^1.4.13"
           }
-        },
-        "tslib": {
-          "version": "1.14.1",
-          "resolved": "https://registry.npmjs.org/tslib/-/tslib-1.14.1.tgz",
-          "integrity": "sha512-Xni35NKzjgMrwevysHTCArtLDpPvye8zV/0E4EyYn43P7/7qvQwPh9BGkHewbMulVntbigmcT7rdX3BNo9wRJg==",
-          "dev": true
         }
       }
     },
@@ -22531,12 +22560,12 @@
       }
     },
     "jest-mock-extended": {
-      "version": "3.0.1",
-      "resolved": "https://registry.npmjs.org/jest-mock-extended/-/jest-mock-extended-3.0.1.tgz",
-      "integrity": "sha512-RF4Ow8pXvbRuEcCTj56oYHmig5311BSFvbEGxPNYL51wGKGu93MvVQgx0UpFmjqyBXIcElkZo2Rke88kR1iSKQ==",
+      "version": "3.0.7",
+      "resolved": "https://registry.npmjs.org/jest-mock-extended/-/jest-mock-extended-3.0.7.tgz",
+      "integrity": "sha512-7lsKdLFcW9B9l5NzZ66S/yTQ9k8rFtnwYdCNuRU/81fqDWicNDVhitTSPnrGmNeNm0xyw0JHexEOShrIKRCIRQ==",
       "dev": true,
       "requires": {
-        "ts-essentials": "^7.0.3"
+        "ts-essentials": "^10.0.0"
       }
     },
     "jest-pnp-resolver": {
@@ -24490,6 +24519,21 @@
       "integrity": "sha512-pq2bWo9mVD43nbts2wGv17XLiNLya+GklZ8kaDLV2Z08gDCsGpnKn9BFMepvWuHCbyVvY7J5o5+BVvoQbmlJLg==",
       "dev": true
     },
+    "remeda": {
+      "version": "2.11.0",
+      "resolved": "https://registry.npmjs.org/remeda/-/remeda-2.11.0.tgz",
+      "integrity": "sha512-rQO+zcuNvnTcB2vBctblBARZakY0+wMNtrFGqU1+h4jm5p2APcDKQxUZG2CmMPkSQxa2nauU55GBVS/3Fo83fA==",
+      "requires": {
+        "type-fest": "^4.23.0"
+      },
+      "dependencies": {
+        "type-fest": {
+          "version": "4.25.0",
+          "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-4.25.0.tgz",
+          "integrity": "sha512-bRkIGlXsnGBRBQRAY56UXBm//9qH4bmJfFvq83gSz41N282df+fjy8ofcEgc1sM8geNt5cl6mC2g9Fht1cs8Aw=="
+        }
+      }
+    },
     "require-directory": {
       "version": "2.1.1",
       "resolved": "https://registry.npmjs.org/require-directory/-/require-directory-2.1.1.tgz",
@@ -25344,9 +25388,9 @@
       "integrity": "sha512-8CYSLazCyj0DJDpPIxOFzJG46r93uh6EynYjuey+bxcLltBeqZL7DMfaE5ZPzZNFlav7wx+2TDa/mBl8gkTYzw=="
     },
     "ts-essentials": {
-      "version": "7.0.3",
-      "resolved": "https://registry.npmjs.org/ts-essentials/-/ts-essentials-7.0.3.tgz",
-      "integrity": "sha512-8+gr5+lqO3G84KdiTSMRLtuyJ+nTBVRKuCrK4lidMPdVeEp0uqC875uE5NMcaA7YYMN7XsNiFQuMvasF8HT/xQ==",
+      "version": "10.0.2",
+      "resolved": "https://registry.npmjs.org/ts-essentials/-/ts-essentials-10.0.2.tgz",
+      "integrity": "sha512-Xwag0TULqriaugXqVdDiGZ5wuZpqABZlpwQ2Ho4GDyiu/R2Xjkp/9+zcFxL7uzeLl/QCPrflnvpVYyS3ouT7Zw==",
       "dev": true,
       "requires": {}
     },
@@ -25444,6 +25488,11 @@
         "yn": "3.1.1"
       }
     },
+    "ts-pattern": {
+      "version": "5.3.1",
+      "resolved": "https://registry.npmjs.org/ts-pattern/-/ts-pattern-5.3.1.tgz",
+      "integrity": "sha512-1RUMKa8jYQdNfmnK4jyzBK3/PS/tnjcZ1CW0v1vWDeYe5RBklc/nquw03MEoB66hVBm4BnlCfmOqDVxHyT1DpA=="
+    },
     "tsconfig-paths": {
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/tsconfig-paths/-/tsconfig-paths-4.1.0.tgz",
@@ -25617,9 +25666,9 @@
       }
     },
     "typescript": {
-      "version": "4.9.4",
-      "resolved": "https://registry.npmjs.org/typescript/-/typescript-4.9.4.tgz",
-      "integrity": "sha512-Uz+dTXYzxXXbsFpM86Wh3dKCxrQqUcVMxwU54orwlJjOpO3ao8L7j5lH+dWfTwgCwIuM9GQ2kvVotzYJMXTBZg==",
+      "version": "5.5.4",
+      "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.5.4.tgz",
+      "integrity": "sha512-Mtq29sKDAEYP7aljRgtPOpTvOfbwRWlS6dPRzwjdE+C0R4brX/GUyhHSecbHMFLNBLcJIPt9nl9yG5TZ1weH+Q==",
       "dev": true
     },
     "uc.micro": {
diff --git a/services/api/package.json b/services/api/package.json
index 20949b5b..7c8c127b 100644
--- a/services/api/package.json
+++ b/services/api/package.json
@@ -56,8 +56,10 @@
     "passport-jwt": "4.0.0",
     "rambda": "7.4.0",
     "reflect-metadata": "^0.1.13",
+    "remeda": "2.11.0",
     "rimraf": "^3.0.2",
     "rxjs": "^7.2.0",
+    "ts-pattern": "5.3.1",
     "zod": "3.21.4"
   },
   "devDependencies": {
@@ -84,7 +86,7 @@
     "http-server": "14.1.1",
     "jest": "29.7.0",
     "jest-fail-on-console": "3.1.1",
-    "jest-mock-extended": "3.0.1",
+    "jest-mock-extended": "3.0.7",
     "prettier": "^2.3.2",
     "source-map-support": "^0.5.20",
     "supertest": "^6.1.3",
@@ -93,6 +95,6 @@
     "ts-node": "^10.0.0",
     "tsconfig-paths": "4.1.0",
     "typedoc": "0.26.5",
-    "typescript": "^4.7.4"
+    "typescript": "^5.0.0"
   }
 }
diff --git a/services/api/src/app/auth/permissions/roles.spec.ts b/services/api/src/app/auth/permissions/roles.spec.ts
index 33eb4a3a..d52db0e9 100644
--- a/services/api/src/app/auth/permissions/roles.spec.ts
+++ b/services/api/src/app/auth/permissions/roles.spec.ts
@@ -1,8 +1,9 @@
 import { Membership, MembershipStatus } from '@entities/membership.entity';
-import { ContentPolicy } from '@entities/room.entity';
+import { ContentPolicy, JoinPolicy } from '@entities/room.entity';
 import { RoomFactory } from '@fixtures/messages/room.factory';
 import { UserFactory } from '@fixtures/messages/user.factory';
 import { defineRolesForUser } from './roles';
+import { Role } from '@usecases/auth.service';
 
 describe('defineRolesForUser', () => {
   const user = UserFactory.build();
@@ -14,8 +15,8 @@ describe('defineRolesForUser', () => {
     const userAbility = defineRolesForUser(user, []);
     const otherUserAbility = defineRolesForUser(otherUser, []);
 
-    expect(userAbility.can('manage', room)).toEqual(true);
-    expect(otherUserAbility.can('manage', room)).toEqual(false);
+    expect(userAbility.can(Role.Manage, room)).toEqual(true);
+    expect(otherUserAbility.can(Role.Manage, room)).toEqual(false);
   });
 
   it('grants read and write permissions for joined rooms', () => {
@@ -34,13 +35,13 @@ describe('defineRolesForUser', () => {
     const userAbility = defineRolesForUser(user, memberships);
     const otherUserAbility = defineRolesForUser(otherUser, []);
 
-    expect(userAbility.can('read', room)).toEqual(true);
-    expect(userAbility.can('write', room)).toEqual(true);
-    expect(userAbility.can('manage', room)).toEqual(false);
+    expect(userAbility.can(Role.Read, room)).toEqual(true);
+    expect(userAbility.can(Role.Write, room)).toEqual(true);
+    expect(userAbility.can(Role.Manage, room)).toEqual(false);
 
-    expect(otherUserAbility.can('read', room)).toEqual(false);
-    expect(otherUserAbility.can('write', room)).toEqual(false);
-    expect(otherUserAbility.can('manage', room)).toEqual(false);
+    expect(otherUserAbility.can(Role.Read, room)).toEqual(false);
+    expect(otherUserAbility.can(Role.Write, room)).toEqual(false);
+    expect(otherUserAbility.can(Role.Manage, room)).toEqual(false);
   });
 
   it('grants read permissions for public rooms', () => {
@@ -50,8 +51,38 @@ describe('defineRolesForUser', () => {
 
     const userAbility = defineRolesForUser(user, []);
 
-    expect(userAbility.can('read', room)).toEqual(true);
-    expect(userAbility.can('write', room)).toEqual(false);
-    expect(userAbility.can('manage', room)).toEqual(false);
+    expect(userAbility.can(Role.Read, room)).toEqual(true);
+    expect(userAbility.can(Role.Write, room)).toEqual(false);
+    expect(userAbility.can(Role.Manage, room)).toEqual(false);
+  });
+
+  it('grants join permissions for rooms with a public join policy', () => {
+    const room = RoomFactory.build({
+      joinPolicy: JoinPolicy.Anyone,
+    });
+
+    const userAbility = defineRolesForUser(user, []);
+
+    expect(userAbility.can(Role.Join, room)).toEqual(true);
+  });
+
+  it('grants join permissions for invited users', () => {
+    const room = RoomFactory.build({
+      joinPolicy: JoinPolicy.Invite,
+    });
+    const memberships: Membership[] = [
+      {
+        userId: user.id,
+        roomId: room.id,
+        status: MembershipStatus.PendingInvite,
+        from: 1000,
+      },
+    ];
+
+    const userAbility = defineRolesForUser(user, memberships);
+    const otherUserAbility = defineRolesForUser(otherUser, []);
+
+    expect(userAbility.can(Role.Join, room)).toEqual(true);
+    expect(otherUserAbility.can(Role.Join, room)).toEqual(false);
   });
 });
diff --git a/services/api/src/app/auth/permissions/roles.ts b/services/api/src/app/auth/permissions/roles.ts
index 42b6b9bc..9ff3de2d 100644
--- a/services/api/src/app/auth/permissions/roles.ts
+++ b/services/api/src/app/auth/permissions/roles.ts
@@ -1,37 +1,50 @@
 import { AbilityBuilder, createMongoAbility } from '@casl/ability';
-import { Membership, MembershipStatus } from '@entities/membership.entity';
+import {
+  Membership,
+  isActive,
+  isPendingInvite,
+} from '@entities/membership.entity';
 import { ContentPolicy, JoinPolicy } from '@entities/room.entity';
 import { User } from '@entities/users';
 import { Role } from '@usecases/auth.service';
-import { pluck } from 'rambda';
+import { filter, pipe, map, prop } from 'remeda';
 
 export const defineRolesForUser = (user: User, memberships: Membership[]) => {
   const { can, build } = new AbilityBuilder(createMongoAbility);
 
-  const activeMemberships = memberships.filter(
-    (membership) =>
-      !membership.until && membership.status === MembershipStatus.Joined,
+  const joinedRoomIds = pipe(
+    memberships,
+    filter(isActive),
+    map(prop('roomId')),
+  );
+
+  const pendingInviteRoomIds = pipe(
+    memberships,
+    filter(isPendingInvite),
+    map(prop('roomId')),
   );
-  const roomIds = pluck('roomId', activeMemberships);
 
   can(Role.Manage, 'Room', {
     ownerId: user.id,
   });
 
   can(Role.Write, 'Room', {
-    id: { $in: roomIds },
+    id: { $in: joinedRoomIds },
   });
 
   can(Role.Read, 'Room', {
     contentPolicy: ContentPolicy.Public,
   });
   can(Role.Read, 'Room', {
-    id: { $in: roomIds },
+    id: { $in: joinedRoomIds },
   });
 
   can(Role.Join, 'Room', {
     joinPolicy: JoinPolicy.Anyone,
   });
+  can(Role.Join, 'Room', {
+    id: { $in: pendingInviteRoomIds },
+  });
 
   return build();
 };
diff --git a/services/api/src/app/messages/command.service.ts b/services/api/src/app/messages/command.service.ts
index 6f4f7028..93aa1e29 100644
--- a/services/api/src/app/messages/command.service.ts
+++ b/services/api/src/app/messages/command.service.ts
@@ -8,6 +8,9 @@ import { Dispatcher } from '@entities/messages';
 import { LoremCommandUseCase } from '@usecases/commands/lorem';
 import { ParseCommandUseCase } from '@usecases/commands/parse';
 import { ChangeRoomJoinPolicyUseCase } from '@usecases/rooms/change-room-join-policy';
+import { P, match } from 'ts-pattern';
+import { InviteUseCase } from '@usecases/rooms/invite';
+import { LeaveRoomUseCase } from '@usecases/rooms/leave';
 
 @Injectable()
 export class CommandService {
@@ -16,33 +19,45 @@ export class CommandService {
     private readonly renameRoom: RenameRoomUseCase,
     private readonly lorem: LoremCommandUseCase,
     private readonly help: HelpCommandUseCase,
+    private readonly leave: LeaveRoomUseCase,
     private readonly parse: ParseCommandUseCase,
     private readonly changeRoomJoinPolicy: ChangeRoomJoinPolicyUseCase,
+    private readonly invite: InviteUseCase,
     readonly dispatcher: Dispatcher,
   ) {}
 
   async exec(command: Command, authenticatedUser: User): Promise<void> {
     const { roomId } = command;
-    const { tag, params } = await this.parse.exec(command);
-    switch (tag) {
-      case 'help':
-        await this.help.exec({ roomId, authenticatedUser });
-        break;
-      case 'renameRoom':
-        await this.renameRoom.exec({ ...params, roomId, authenticatedUser });
-        break;
-      case 'renameUser':
-        await this.renameUser.exec({ ...params, roomId, authenticatedUser });
-        break;
-      case 'lorem':
-        await this.lorem.exec({ ...params, roomId, authenticatedUser });
-        break;
-      case 'changeRoomJoinPolicy':
-        await this.changeRoomJoinPolicy.exec({
+    const parsedCommand = await this.parse.exec(command);
+    return match(parsedCommand)
+      .with({ tag: 'help' }, () =>
+        this.help.exec({ roomId, authenticatedUser }),
+      )
+      .with({ tag: 'renameRoom', params: P.select() }, (params) =>
+        this.renameRoom.exec({ ...params, roomId, authenticatedUser }),
+      )
+      .with({ tag: 'renameUser', params: P.select() }, (params) =>
+        this.renameUser.exec({ ...params, roomId, authenticatedUser }),
+      )
+      .with({ tag: 'lorem', params: P.select() }, (params) =>
+        this.lorem.exec({ ...params, roomId, authenticatedUser }),
+      )
+      .with({ tag: 'changeRoomJoinPolicy', params: P.select() }, (params) =>
+        this.changeRoomJoinPolicy.exec({
           ...params,
           roomId,
           authenticatedUser,
-        });
-    }
+        }),
+      )
+      .with({ tag: 'leave' }, () =>
+        this.leave.exec({
+          roomId,
+          authenticatedUser,
+        }),
+      )
+      .with({ tag: 'inviteUser', params: P.select() }, (params) => {
+        this.invite.exec({ ...params, roomId, authenticatedUser });
+      })
+      .exhaustive();
   }
 }
diff --git a/services/api/src/app/messages/messages.module.ts b/services/api/src/app/messages/messages.module.ts
index 4065e3dd..578feba3 100644
--- a/services/api/src/app/messages/messages.module.ts
+++ b/services/api/src/app/messages/messages.module.ts
@@ -13,6 +13,8 @@ import { LoremCommandUseCase, LoremGenerator } from '@usecases/commands/lorem';
 import { FakerLoremGenerator } from './faker.lorem.generator';
 import { DispatcherModule } from '../dispatcher/dispatcher.module';
 import { ChangeRoomJoinPolicyUseCase } from '@usecases/rooms/change-room-join-policy';
+import { InviteUseCase } from '@usecases/rooms/invite';
+import { LeaveRoomUseCase } from '@usecases/rooms/leave';
 
 @Module({
   imports: [AuthModule, DispatcherModule],
@@ -30,6 +32,8 @@ import { ChangeRoomJoinPolicyUseCase } from '@usecases/rooms/change-room-join-po
     RenameRoomUseCase,
     RenameUserUseCase,
     ChangeRoomJoinPolicyUseCase,
+    InviteUseCase,
+    LeaveRoomUseCase,
     LoremCommandUseCase,
     HelpCommandUseCase,
   ],
diff --git a/services/api/src/app/users/users.service.ts b/services/api/src/app/users/users.service.ts
index 54ffa5be..3ef54ce4 100644
--- a/services/api/src/app/users/users.service.ts
+++ b/services/api/src/app/users/users.service.ts
@@ -1,11 +1,11 @@
-import { MembershipStatus } from '@entities/membership.entity';
+import { isActive } from '@entities/membership.entity';
 import { MembershipsRepository } from '@entities/memberships.repository';
 import { Room } from '@entities/room.entity';
 import { RoomsRepository } from '@entities/rooms.repository';
-import { User } from '@entities/users';
+import { User, systemUser } from '@entities/users';
 import { UsersRepository } from '@entities/users';
 import { Injectable } from '@nestjs/common';
-import { filter, pluck, uniq } from 'rambda';
+import { filter, map, prop, pipe } from 'remeda';
 
 @Injectable()
 export class UsersService {
@@ -17,21 +17,14 @@ export class UsersService {
 
   async getUser(userId: string): Promise<User> {
     if (userId === 'system') {
-      return {
-        id: 'system',
-        name: 'System',
-      };
+      return systemUser;
     }
     return await this.usersRepo.getUser(userId);
   }
 
   async getUserRooms(userId: string): Promise<Room[]> {
     const memberships = await this.membershipsRepo.getMemberships(userId);
-    const activeMemberships = filter(
-      (m) => !m.until && m.status === MembershipStatus.Joined,
-      memberships,
-    );
-    const roomIds = uniq(pluck('roomId', activeMemberships));
+    const roomIds = pipe(memberships, filter(isActive), map(prop('roomId')));
     const rooms = await Promise.all(
       roomIds.map((roomId) => this.roomsRepo.getRoom(roomId)),
     );
diff --git a/services/api/src/data/adapters/schema.ts b/services/api/src/data/adapters/schema.ts
index 3fd122a8..35af9673 100644
--- a/services/api/src/data/adapters/schema.ts
+++ b/services/api/src/data/adapters/schema.ts
@@ -14,6 +14,7 @@ export const DbSchema = {
       Sort: { type: String, value: 'user', required: true },
       sub: { type: String, required: true },
       name: { type: String, required: true },
+      email: { type: String, required: true, unique: true },
       picture: { type: String },
     },
     Message: {
@@ -58,6 +59,7 @@ export const DbSchema = {
         enum: [
           MembershipStatus.None,
           MembershipStatus.Joined,
+          MembershipStatus.PendingInvite,
           MembershipStatus.PendingApproval,
           MembershipStatus.Revoked,
         ],
diff --git a/services/api/src/data/repositories/dynamodb.users.repository.e2e-spec.ts b/services/api/src/data/repositories/dynamodb.users.repository.e2e-spec.ts
index 8b88d8ab..20526b00 100644
--- a/services/api/src/data/repositories/dynamodb.users.repository.e2e-spec.ts
+++ b/services/api/src/data/repositories/dynamodb.users.repository.e2e-spec.ts
@@ -1,9 +1,11 @@
 import { DynamoDBUsersRepository } from '@data/repositories/dynamodb.users.repository';
-import { SaveUserParams } from '@entities/users';
+import { userParamsFromAuth } from '@entities/users';
 import { TestUsersRepository } from '@fixtures/data/test.users.repository';
 import { Test, TestingModule } from '@nestjs/testing';
 import { DataModule } from '../data.module';
 import { MockLoggerModule } from '@fixtures/MockLoggerModule';
+import { AuthInfoFactory } from '@fixtures/auth/auth-info.factory';
+import { omit } from 'remeda';
 
 type TestCase = {
   name: 'DynamoDBUsersRepository' | 'TestUsersRepository';
@@ -35,30 +37,31 @@ describe('RoomsRepository', () => {
   test.each(testCases)('[$name] stores and finds users', async ({ name }) => {
     const repo = repos[name];
 
-    const params: SaveUserParams = {
-      sub: 'google_123',
-      name: 'Some User',
-    };
+    const params = userParamsFromAuth(AuthInfoFactory.build());
 
     const user = await repo.saveUser(params);
-    const found = await repo.getUser('user:google_123');
+    const found = await repo.getUser(user.id);
 
-    expect(user).toMatchObject({
-      id: 'user:google_123',
-      name: 'Some User',
-    });
-    expect(found).toMatchObject({
-      id: 'user:google_123',
-      name: 'Some User',
-    });
+    expect(user).toMatchObject(omit(params, ['sub']));
+    expect(found).toMatchObject(user);
+  });
+
+  test.each(testCases)('[$name] finds users by email', async ({ name }) => {
+    const repo = repos[name];
+
+    const params = userParamsFromAuth(AuthInfoFactory.build());
+
+    const user = await repo.saveUser(params);
+    const found = await repo.findUser(params.email);
+
+    expect(found).toMatchObject(user);
+
+    expect(await repo.findUser('not-a-user@example.com')).toBeNull();
   });
 
   test.each(testCases)('[$name] updates users', async ({ name }) => {
     const repo = repos[name];
-    const params: SaveUserParams = {
-      name: 'Some User',
-      sub: 'user:google_123',
-    };
+    const params = userParamsFromAuth(AuthInfoFactory.build());
     const user = await repo.saveUser(params);
 
     const updated = await repo.updateUser({
diff --git a/services/api/src/data/repositories/dynamodb.users.repository.ts b/services/api/src/data/repositories/dynamodb.users.repository.ts
index 7217c9ea..a6cb84e4 100644
--- a/services/api/src/data/repositories/dynamodb.users.repository.ts
+++ b/services/api/src/data/repositories/dynamodb.users.repository.ts
@@ -34,6 +34,20 @@ export class DynamoDBUsersRepository extends UsersRepository {
     return userFromRecord(user);
   }
 
+  override async findUser(email: string): Promise<User | null> {
+    const [user] = await this.adapter.User.scan(
+      {},
+      {
+        where: '${email} = @{email}',
+        substitutions: {
+          email,
+        },
+        hidden: true,
+      },
+    );
+    return user ? userFromRecord(user) : null;
+  }
+
   override async updateUser(params: UpdateUserParams): Promise<User> {
     const { id, ...rest } = params;
     const user = await this.adapter.User.get(
@@ -57,5 +71,5 @@ export class DynamoDBUsersRepository extends UsersRepository {
 
 const userFromRecord = (record: DbUser): User => ({
   id: record.Id,
-  ...pick(['name', 'picture'], record),
+  ...pick(['name', 'picture', 'email'], record),
 });
diff --git a/services/api/src/domain/entities/membership.entity.ts b/services/api/src/domain/entities/membership.entity.ts
index 8a56c7e5..1ebc8858 100644
--- a/services/api/src/domain/entities/membership.entity.ts
+++ b/services/api/src/domain/entities/membership.entity.ts
@@ -1,3 +1,6 @@
+import { isNil } from 'rambda';
+import { allPass } from 'remeda';
+
 /**
  * The status of a user's membership to a room.
  */
@@ -12,6 +15,12 @@ export enum MembershipStatus {
    */
   Joined = 'Joined',
 
+  /**
+   * The user has been invited by an admin but has not accepted.
+   */
+
+  PendingInvite = 'PendingInvite',
+
   /**
    * The user has requested to join a room but is pending approval.
    */
@@ -53,3 +62,28 @@ export type Membership = {
    */
   until?: number;
 };
+
+export const isCurrent = (membership: Membership) => isNil(membership.until);
+
+export const withStatus =
+  (status: MembershipStatus) => (membership: Membership) =>
+    membership.status === status;
+
+export const forRoom = (roomId: string) => (membership: Membership) =>
+  membership.roomId === roomId;
+
+export const isActive = allPass([
+  isCurrent,
+  withStatus(MembershipStatus.Joined),
+]);
+
+export const isPendingInvite = allPass([
+  isCurrent,
+  withStatus(MembershipStatus.PendingInvite),
+]);
+
+export const isMemberOf = (roomId: string, memberships: Membership[]) =>
+  memberships.some(allPass([isActive, forRoom(roomId)]));
+
+export const hasInviteTo = (roomId: string, memberships: Membership[]) =>
+  memberships.some(allPass([isPendingInvite, forRoom(roomId)]));
diff --git a/services/api/src/domain/entities/memberships.repository.ts b/services/api/src/domain/entities/memberships.repository.ts
index f6217108..8142ff38 100644
--- a/services/api/src/domain/entities/memberships.repository.ts
+++ b/services/api/src/domain/entities/memberships.repository.ts
@@ -11,5 +11,6 @@ export abstract class MembershipsRepository {
   abstract createMembership(
     params: CreateMembershipParams,
   ): Promise<Membership>;
+
   abstract getMemberships(userId: string): Promise<Membership[]>;
 }
diff --git a/services/api/src/domain/entities/users/system.ts b/services/api/src/domain/entities/users/system.ts
index 03501ac3..e19834b9 100644
--- a/services/api/src/domain/entities/users/system.ts
+++ b/services/api/src/domain/entities/users/system.ts
@@ -1,8 +1,10 @@
 import { SentMessage, DraftMessage } from '../messages/message';
+import { User } from './user.entity';
 
-export const systemUser = Object.freeze({
+export const systemUser: User = Object.freeze({
   id: 'system',
   name: 'System',
+  email: 'system@example.com',
 });
 
 export const isSystemMessage = (message: SentMessage): boolean => {
diff --git a/services/api/src/domain/entities/users/user.entity.ts b/services/api/src/domain/entities/users/user.entity.ts
index 62dee3c5..e76ebdaa 100644
--- a/services/api/src/domain/entities/users/user.entity.ts
+++ b/services/api/src/domain/entities/users/user.entity.ts
@@ -1,5 +1,6 @@
 export class User {
   id: string;
   name: string;
+  email: string;
   picture?: string;
 }
diff --git a/services/api/src/domain/entities/users/users.repository.ts b/services/api/src/domain/entities/users/users.repository.ts
index ad3533bb..a8b60ec4 100644
--- a/services/api/src/domain/entities/users/users.repository.ts
+++ b/services/api/src/domain/entities/users/users.repository.ts
@@ -4,6 +4,7 @@ import { AuthInfo } from '@entities/auth';
 
 export type SaveUserParams = AuthInfo & {
   name: string;
+  email: string;
 };
 
 export type UpdateUserParams = Partial<Pick<User, 'name'>> & Pick<User, 'id'>;
@@ -11,11 +12,19 @@ export type UpdateUserParams = Partial<Pick<User, 'name'>> & Pick<User, 'id'>;
 export abstract class UsersRepository {
   abstract saveUser(params: SaveUserParams): Promise<User>;
   abstract getUser(id: string): Promise<User>;
+  abstract findUser(email: string): Promise<User | null>;
   abstract updateUser(params: UpdateUserParams): Promise<User>;
 }
 
-export const userParamsFromAuth = (authInfo: AuthInfo): SaveUserParams => ({
-  sub: authInfo.sub,
-  name: authInfo.name ?? `${faker.word.adverb()}-${faker.animal.bird()}`,
-  picture: authInfo.picture,
-});
+export const userParamsFromAuth = (authInfo: AuthInfo): SaveUserParams => {
+  if (!authInfo.email) {
+    throw new Error('Missing email');
+  }
+
+  return {
+    sub: authInfo.sub,
+    email: authInfo.email,
+    name: authInfo.name ?? `${faker.word.adverb()}-${faker.animal.bird()}`,
+    picture: authInfo.picture,
+  };
+};
diff --git a/services/api/src/domain/usecases/commands/help.spec.ts b/services/api/src/domain/usecases/commands/help.spec.ts
index d0b86796..2102159f 100644
--- a/services/api/src/domain/usecases/commands/help.spec.ts
+++ b/services/api/src/domain/usecases/commands/help.spec.ts
@@ -32,7 +32,9 @@ describe('HelpCommandUseCase', () => {
         "* `/lorem {count} {'words' | 'paragraphs'}`: generate lorem text",
         '* `/rename room {name}`: change the room name',
         '* `/rename user {name}`: change your display name',
+        '* `/leave`: leave room',
         "* `/set room join policy {'anyone', 'invite'}`: set the room join policy",
+        '* `/invite {email}`: invite a user to the room',
       ].join('\n'),
     });
   });
diff --git a/services/api/src/domain/usecases/commands/parse/command.parser.ts b/services/api/src/domain/usecases/commands/parse/command.parser.ts
index f173a496..55069e3d 100644
--- a/services/api/src/domain/usecases/commands/parse/command.parser.ts
+++ b/services/api/src/domain/usecases/commands/parse/command.parser.ts
@@ -8,6 +8,8 @@ export type ParsedCommand =
   | { tag: 'help'; params: null }
   | { tag: 'renameRoom'; params: { newName: string } }
   | { tag: 'renameUser'; params: { newName: string } }
+  | { tag: 'inviteUser'; params: { email: string } }
+  | { tag: 'leave'; params: null }
   | { tag: 'changeRoomJoinPolicy'; params: { newJoinPolicy: JoinPolicy } }
   | {
       tag: 'lorem';
diff --git a/services/api/src/domain/usecases/commands/parse/parse.spec.ts b/services/api/src/domain/usecases/commands/parse/parse.spec.ts
index 16abf5b3..8a3f6adc 100644
--- a/services/api/src/domain/usecases/commands/parse/parse.spec.ts
+++ b/services/api/src/domain/usecases/commands/parse/parse.spec.ts
@@ -2,6 +2,7 @@ import { Command } from '@entities/command.entity';
 import { BadRequestException } from '@nestjs/common';
 import { ParseCommandUseCase } from '.';
 import { ParsedCommand } from './command.parser';
+import { JoinPolicy } from '@entities/room.entity';
 
 describe('ParseCommandUseCase', () => {
   let parse: ParseCommandUseCase;
@@ -118,6 +119,76 @@ describe('ParseCommandUseCase', () => {
     });
   });
 
+  describe('/rename user', () => {
+    it('parses valid commands', () => {
+      withMessage('/rename user My User').expectCommand({
+        tag: 'renameUser',
+        params: {
+          newName: 'My User',
+        },
+      });
+    });
+
+    it('validates the number of arguments', () => {
+      withMessage('/rename user').expectError(
+        'Error in command `/rename user`:',
+        `* Received too few arguments. Expected: \`/rename user {name}\``,
+      );
+    });
+  });
+
+  describe('/leave', () => {
+    it('parses valid commands', () => {
+      withMessage('/leave').expectCommand({
+        tag: 'leave',
+        params: null,
+      });
+    });
+  });
+
+  describe('/set room join policy', () => {
+    it('parses valid commands', () => {
+      withMessage('/set room join policy anyone').expectCommand({
+        tag: 'changeRoomJoinPolicy',
+        params: {
+          newJoinPolicy: JoinPolicy.Anyone,
+        },
+      });
+    });
+
+    it('validates the number of arguments', () => {
+      withMessage('/set room join policy').expectError(
+        'Error in command `/set room join policy`:',
+        `* Received too few arguments. Expected: \`/set room join policy {'anyone', 'invite'}\``,
+      );
+    });
+  });
+
+  describe('/invite', () => {
+    it('parses valid commands', () => {
+      withMessage('/invite joe.bloggs@example.com').expectCommand({
+        tag: 'inviteUser',
+        params: {
+          email: 'joe.bloggs@example.com',
+        },
+      });
+    });
+
+    it('validates the number of arguments', () => {
+      withMessage('/invite').expectError(
+        'Error in command `/invite`:',
+        `* Received too few arguments. Expected: \`/invite {email}\``,
+      );
+    });
+
+    it('validates the email', () => {
+      withMessage('/invite not-an-email').expectError(
+        'Error in command `/invite not-an-email`:',
+        `* Argument 1 (\`not-an-email\`): Invalid email`,
+      );
+    });
+  });
+
   it('responds if the command is unrecognised', () => {
     const command: Command = {
       roomId: 'my-room',
diff --git a/services/api/src/domain/usecases/commands/parse/parsers/index.ts b/services/api/src/domain/usecases/commands/parse/parsers/index.ts
index 316ff6d6..4b7a7a4d 100644
--- a/services/api/src/domain/usecases/commands/parse/parsers/index.ts
+++ b/services/api/src/domain/usecases/commands/parse/parsers/index.ts
@@ -1,6 +1,8 @@
 import { CommandParser } from '../command.parser';
 import { changeRoomJoinPolicyParser } from './change-room-join-policy-parser';
 import { helpParser } from './help.parser';
+import { inviteParser } from './invite-parser';
+import { leaveParser } from './leave.parser';
 import { loremParser } from './lorem.parser';
 import { renameRoomParser } from './rename.room.parser';
 import { renameUserParser } from './rename.user.parser';
@@ -10,5 +12,7 @@ export const parsers: CommandParser[] = [
   loremParser,
   renameRoomParser,
   renameUserParser,
+  leaveParser,
   changeRoomJoinPolicyParser,
+  inviteParser,
 ];
diff --git a/services/api/src/domain/usecases/commands/parse/parsers/invite-parser.ts b/services/api/src/domain/usecases/commands/parse/parsers/invite-parser.ts
new file mode 100644
index 00000000..8d2a4d78
--- /dev/null
+++ b/services/api/src/domain/usecases/commands/parse/parsers/invite-parser.ts
@@ -0,0 +1,16 @@
+import { z } from 'zod';
+import { CommandParser, ParsedCommand } from '../command.parser';
+
+const schema = z
+  .tuple([z.literal('invite'), z.string().email()])
+  .transform<ParsedCommand>(([, email]) => ({
+    tag: 'inviteUser',
+    params: { email },
+  }));
+
+export const inviteParser = new CommandParser({
+  matchTokens: ['invite'],
+  schema,
+  signature: `/invite {email}`,
+  summary: 'invite a user to the room',
+});
diff --git a/services/api/src/domain/usecases/commands/parse/parsers/leave.parser.ts b/services/api/src/domain/usecases/commands/parse/parsers/leave.parser.ts
new file mode 100644
index 00000000..e11e4424
--- /dev/null
+++ b/services/api/src/domain/usecases/commands/parse/parsers/leave.parser.ts
@@ -0,0 +1,14 @@
+import { z } from 'zod';
+import { CommandParser, ParsedCommand } from '../command.parser';
+
+const schema = z.tuple([z.literal('leave')]).transform<ParsedCommand>(() => ({
+  tag: 'leave',
+  params: null,
+}));
+
+export const leaveParser = new CommandParser({
+  matchTokens: ['leave'],
+  schema,
+  signature: '/leave',
+  summary: 'leave room',
+});
diff --git a/services/api/src/domain/usecases/rooms/invite.spec.ts b/services/api/src/domain/usecases/rooms/invite.spec.ts
new file mode 100644
index 00000000..799f1842
--- /dev/null
+++ b/services/api/src/domain/usecases/rooms/invite.spec.ts
@@ -0,0 +1,148 @@
+import { JoinPolicy } from '@entities/room.entity';
+import { TestAuthService } from '@fixtures/auth/test-auth-service';
+import { TestMembershipsRepository } from '@fixtures/data/test.memberships.repository';
+import { TestRoomsRepository } from '@fixtures/data/test.rooms.repository';
+import { RoomFactory } from '@fixtures/messages/room.factory';
+import { UserFactory } from '@fixtures/messages/user.factory';
+import { UnauthorizedException } from '@nestjs/common';
+import { AppLogger } from '@app/app.logger';
+import { Role } from '@usecases/auth.service';
+import mock, { MockProxy } from 'jest-mock-extended/lib/Mock';
+import { Dispatcher } from '@entities/messages/message';
+import { InviteUseCase } from './invite';
+import { TestUsersRepository } from '@fixtures/data/test.users.repository';
+import { MembershipStatus } from '@entities/membership.entity';
+
+describe('InviteUseCase', () => {
+  let invite: InviteUseCase;
+  let rooms: TestRoomsRepository;
+  let users: TestUsersRepository;
+  let memberships: TestMembershipsRepository;
+  let auth: TestAuthService;
+  let dispatcher: MockProxy<Dispatcher>;
+
+  const owner = UserFactory.build({ name: 'Alice' });
+  const otherUser = UserFactory.build({ name: 'Bob' });
+  const room = RoomFactory.build({ joinPolicy: JoinPolicy.Invite });
+
+  const now = new Date(1000);
+
+  beforeEach(() => {
+    rooms = new TestRoomsRepository();
+    rooms.setData([room]);
+
+    users = new TestUsersRepository();
+    users.setData([owner, otherUser]);
+
+    memberships = new TestMembershipsRepository();
+
+    auth = new TestAuthService(mock<AppLogger>());
+    auth.stubPermission({ user: owner, subject: room, action: Role.Manage });
+
+    dispatcher = mock<Dispatcher>();
+
+    invite = new InviteUseCase(rooms, users, memberships, auth, dispatcher);
+
+    jest.useFakeTimers({ now });
+  });
+
+  it('invites a user to the room', async () => {
+    await invite.exec({
+      authenticatedUser: owner,
+      roomId: room.id,
+      email: otherUser.email,
+    });
+
+    expect(memberships.getData()).toEqual([
+      {
+        userId: otherUser.id,
+        roomId: room.id,
+        status: MembershipStatus.PendingInvite,
+        from: now.getTime(),
+      },
+    ]);
+
+    expect(dispatcher.send).toHaveBeenCalledWith({
+      content: 'Alice invited Bob to join the room',
+      authorId: 'system',
+      roomId: room.id,
+    });
+  });
+
+  it('authorizes the user', async () => {
+    await expect(
+      invite.exec({
+        authenticatedUser: otherUser,
+        roomId: room.id,
+        email: otherUser.email,
+      }),
+    ).rejects.toEqual(
+      new UnauthorizedException(
+        'You do not have permission to perform this action.',
+      ),
+    );
+  });
+
+  it('checks the user exists', async () => {
+    await invite.exec({
+      authenticatedUser: owner,
+      roomId: room.id,
+      email: 'not-a-user@example.com',
+    });
+
+    expect(dispatcher.send).toHaveBeenCalledWith({
+      content: 'No user exists with email not-a-user@example.com',
+      authorId: 'system',
+      roomId: room.id,
+      recipientId: owner.id,
+    });
+  });
+
+  it('checks the user is not already a member', async () => {
+    await memberships.setData([
+      {
+        from: 0,
+        roomId: room.id,
+        userId: otherUser.id,
+        status: MembershipStatus.Joined,
+      },
+    ]);
+
+    await invite.exec({
+      authenticatedUser: owner,
+      roomId: room.id,
+      email: otherUser.email,
+    });
+
+    expect(dispatcher.send).toHaveBeenCalledWith({
+      content: 'Bob is already a member of this room',
+      authorId: 'system',
+      roomId: room.id,
+      recipientId: owner.id,
+    });
+  });
+
+  it('checks the user doesn not already have an invite', async () => {
+    await memberships.setData([
+      {
+        from: 0,
+        roomId: room.id,
+        userId: otherUser.id,
+        status: MembershipStatus.PendingInvite,
+      },
+    ]);
+
+    await invite.exec({
+      authenticatedUser: owner,
+      roomId: room.id,
+      email: otherUser.email,
+    });
+
+    expect(dispatcher.send).toHaveBeenCalledWith({
+      content: 'Bob already has an invite to this room',
+      authorId: 'system',
+      roomId: room.id,
+      recipientId: owner.id,
+    });
+  });
+});
diff --git a/services/api/src/domain/usecases/rooms/invite.ts b/services/api/src/domain/usecases/rooms/invite.ts
new file mode 100644
index 00000000..24f2c1ba
--- /dev/null
+++ b/services/api/src/domain/usecases/rooms/invite.ts
@@ -0,0 +1,95 @@
+import { AuthService, Role } from '@usecases/auth.service';
+import {
+  MembershipStatus,
+  hasInviteTo,
+  isMemberOf,
+} from '@entities/membership.entity';
+import { MembershipsRepository } from '@entities/memberships.repository';
+import { RoomsRepository } from '@entities/rooms.repository';
+import { User, UsersRepository } from '@entities/users';
+import { Injectable } from '@nestjs/common';
+import { Dispatcher, DraftMessage } from '@entities/messages/message';
+
+export type InviteParams = {
+  roomId: string;
+  authenticatedUser: User;
+  email: string;
+};
+
+@Injectable()
+export class InviteUseCase {
+  constructor(
+    private readonly rooms: RoomsRepository,
+    private readonly users: UsersRepository,
+    private readonly memberships: MembershipsRepository,
+    private readonly authService: AuthService,
+    private readonly dispatcher: Dispatcher,
+  ) {}
+
+  async exec({
+    roomId,
+    authenticatedUser,
+    email,
+  }: InviteParams): Promise<void> {
+    const room = await this.rooms.getRoom(roomId);
+
+    await this.authService.authorize({
+      user: authenticatedUser,
+      action: Role.Manage,
+      subject: room,
+    });
+
+    const invitedUser = await this.users.findUser(email);
+
+    if (!invitedUser) {
+      const message: DraftMessage = {
+        content: `No user exists with email ${email}`,
+        roomId: room.id,
+        authorId: 'system',
+        recipientId: authenticatedUser.id,
+      };
+
+      await this.dispatcher.send(message);
+      return;
+    }
+
+    const existingMemberships = await this.memberships.getMemberships(
+      invitedUser.id,
+    );
+    if (isMemberOf(roomId, existingMemberships)) {
+      const message: DraftMessage = {
+        content: `${invitedUser.name} is already a member of this room`,
+        roomId: room.id,
+        authorId: 'system',
+        recipientId: authenticatedUser.id,
+      };
+
+      await this.dispatcher.send(message);
+      return;
+    } else if (hasInviteTo(roomId, existingMemberships)) {
+      const message: DraftMessage = {
+        content: `${invitedUser.name} already has an invite to this room`,
+        roomId: room.id,
+        authorId: 'system',
+        recipientId: authenticatedUser.id,
+      };
+
+      await this.dispatcher.send(message);
+      return;
+    }
+
+    await this.memberships.createMembership({
+      userId: invitedUser.id,
+      roomId,
+      status: MembershipStatus.PendingInvite,
+    });
+
+    const message: DraftMessage = {
+      content: `${authenticatedUser.name} invited ${invitedUser.name} to join the room`,
+      roomId: room.id,
+      authorId: 'system',
+    };
+
+    await this.dispatcher.send(message);
+  }
+}
diff --git a/services/api/src/domain/usecases/rooms/leave.spec.ts b/services/api/src/domain/usecases/rooms/leave.spec.ts
new file mode 100644
index 00000000..26204bca
--- /dev/null
+++ b/services/api/src/domain/usecases/rooms/leave.spec.ts
@@ -0,0 +1,59 @@
+import { JoinPolicy } from '@entities/room.entity';
+import { TestAuthService } from '@fixtures/auth/test-auth-service';
+import { TestMembershipsRepository } from '@fixtures/data/test.memberships.repository';
+import { TestRoomsRepository } from '@fixtures/data/test.rooms.repository';
+import { RoomFactory } from '@fixtures/messages/room.factory';
+import { UserFactory } from '@fixtures/messages/user.factory';
+import { AppLogger } from '@app/app.logger';
+import { Role } from '@usecases/auth.service';
+import mock, { MockProxy } from 'jest-mock-extended/lib/Mock';
+import { Dispatcher, UpdatedEntity } from '@entities/messages/message';
+import { LeaveRoomUseCase } from './leave';
+import { MembershipStatus } from '@entities/membership.entity';
+
+describe('LeaveRoomUseCase', () => {
+  let leave: LeaveRoomUseCase;
+  let rooms: TestRoomsRepository;
+  let memberships: TestMembershipsRepository;
+  let auth: TestAuthService;
+  let dispatcher: MockProxy<Dispatcher>;
+
+  const user = UserFactory.build({ name: 'Joe Bloggs' });
+
+  const now = new Date(1000);
+
+  beforeEach(() => {
+    rooms = new TestRoomsRepository();
+    memberships = new TestMembershipsRepository();
+    auth = new TestAuthService(mock<AppLogger>());
+    dispatcher = mock<Dispatcher>();
+    leave = new LeaveRoomUseCase(rooms, memberships, dispatcher);
+    jest.useFakeTimers({ now });
+  });
+
+  it('assigns a membership to the user', async () => {
+    const room = RoomFactory.build({
+      joinPolicy: JoinPolicy.Anyone,
+    });
+    rooms.setData([room]);
+    auth.stubPermission({ user, subject: room, action: Role.Read });
+
+    await leave.exec({ authenticatedUser: user, roomId: room.id });
+
+    expect(memberships.getData()).toEqual([
+      {
+        userId: user.id,
+        roomId: room.id,
+        status: MembershipStatus.Revoked,
+        from: now.getTime(),
+      },
+    ]);
+
+    expect(dispatcher.send).toHaveBeenCalledWith({
+      content: 'Joe Bloggs left the room.',
+      authorId: 'system',
+      roomId: room.id,
+      updatedEntities: [UpdatedEntity.Room, UpdatedEntity.Users],
+    });
+  });
+});
diff --git a/services/api/src/domain/usecases/rooms/leave.ts b/services/api/src/domain/usecases/rooms/leave.ts
new file mode 100644
index 00000000..faccff4a
--- /dev/null
+++ b/services/api/src/domain/usecases/rooms/leave.ts
@@ -0,0 +1,43 @@
+import { MembershipStatus } from '@entities/membership.entity';
+import { MembershipsRepository } from '@entities/memberships.repository';
+import { RoomsRepository } from '@entities/rooms.repository';
+import { User } from '@entities/users';
+import { Injectable } from '@nestjs/common';
+import {
+  Dispatcher,
+  DraftMessage,
+  UpdatedEntity,
+} from '@entities/messages/message';
+
+export type LeaveRoomParams = {
+  roomId: string;
+  authenticatedUser: User;
+};
+
+@Injectable()
+export class LeaveRoomUseCase {
+  constructor(
+    private readonly rooms: RoomsRepository,
+    private readonly memberships: MembershipsRepository,
+    private readonly dispatcher: Dispatcher,
+  ) {}
+
+  async exec({ roomId, authenticatedUser }: LeaveRoomParams): Promise<void> {
+    const room = await this.rooms.getRoom(roomId);
+
+    await this.memberships.createMembership({
+      userId: authenticatedUser.id,
+      roomId,
+      status: MembershipStatus.Revoked,
+    });
+
+    const message: DraftMessage = {
+      content: `${authenticatedUser.name} left the room.`,
+      roomId: room.id,
+      authorId: 'system',
+      updatedEntities: [UpdatedEntity.Room, UpdatedEntity.Users],
+    };
+
+    await this.dispatcher.send(message);
+  }
+}
diff --git a/services/api/src/fixtures/auth/FakeAuth.ts b/services/api/src/fixtures/auth/FakeAuth.ts
index 3b879648..3c7f4495 100644
--- a/services/api/src/fixtures/auth/FakeAuth.ts
+++ b/services/api/src/fixtures/auth/FakeAuth.ts
@@ -32,6 +32,7 @@ export const fakeAuthUser = (
   const user: User = {
     id: `user:${userParams.sub}`,
     name: userParams.name,
+    email: userParams.email,
     picture: userParams.picture,
   };
   const fakeAuth = {
diff --git a/services/api/src/fixtures/auth/auth-info.factory.ts b/services/api/src/fixtures/auth/auth-info.factory.ts
index e4034bc8..34f9d3d4 100644
--- a/services/api/src/fixtures/auth/auth-info.factory.ts
+++ b/services/api/src/fixtures/auth/auth-info.factory.ts
@@ -5,6 +5,7 @@ export const AuthInfoFactory = {
   build: (overrides?: Partial<AuthInfo>): AuthInfo => ({
     sub: overrides?.sub ?? `google-${faker.datatype.uuid()}`,
     name: overrides?.name ?? faker.name.fullName(),
+    email: overrides?.email ?? faker.internet.email(),
     picture: overrides?.picture ?? faker.internet.avatar(),
   }),
 };
diff --git a/services/api/src/fixtures/data/test.users.repository.ts b/services/api/src/fixtures/data/test.users.repository.ts
index fa892a2e..c8199b88 100644
--- a/services/api/src/fixtures/data/test.users.repository.ts
+++ b/services/api/src/fixtures/data/test.users.repository.ts
@@ -16,9 +16,13 @@ export class TestUsersRepository extends UsersRepository {
   }
 
   override async saveUser(params: AuthInfo): Promise<User> {
+    if (!params.email) {
+      throw new Error('Requires email');
+    }
     const user = {
       id: `user:${params.sub}`,
       name: params.name ?? 'Anon',
+      email: params.email,
       picture: params.picture,
     };
     this.users.push(user);
@@ -33,6 +37,10 @@ export class TestUsersRepository extends UsersRepository {
     return user;
   }
 
+  override async findUser(email: string): Promise<User | null> {
+    return find((user) => email === user.email, this.users) ?? null;
+  }
+
   override async updateUser(params: UpdateUserParams): Promise<User> {
     const user = find((user) => params.id === user.id, this.users);
     if (!user) {
diff --git a/services/api/src/fixtures/messages/user.factory.ts b/services/api/src/fixtures/messages/user.factory.ts
index cb241311..e026ee19 100644
--- a/services/api/src/fixtures/messages/user.factory.ts
+++ b/services/api/src/fixtures/messages/user.factory.ts
@@ -6,6 +6,7 @@ export const UserFactory = {
   build: (overrides?: Partial<User>): User => ({
     id: overrides?.id ?? UserFactory.id(),
     name: overrides?.name ?? faker.name.fullName(),
+    email: overrides?.email ?? faker.internet.email(),
     picture: overrides?.picture ?? faker.internet.avatar(),
   }),
 };