Learnt from: ggazzo
Repo: RocketChat/Rocket.Chat PR: 35995
File: apps/meteor/app/api/server/v1/rooms.ts:1107-1112
Timestamp: 2026-02-23T17:53:18.785Z
Learning: In Rocket.Chat PR reviews, maintain strict scope boundaries—when a PR is focused on a specific endpoint (e.g., rooms.favorite), avoid reviewing or suggesting changes to other endpoints that were incidentally refactored (e.g., rooms.invite) unless explicitly requested by maintainers.

Learnt from: ricardogarim
Repo: RocketChat/Rocket.Chat PR: 40100
File: apps/meteor/client/views/root/MainLayout/EmbeddedPreload.tsx:18-35
Timestamp: 2026-04-13T16:40:55.864Z
Learning: In Rocket.Chat's embedded mode (`?layout=embedded`), route changes are driven by the parent frame reloading the iframe URL, which causes a full remount of the React tree (including `EmbeddedPreload` at `apps/meteor/client/views/root/MainLayout/EmbeddedPreload.tsx`). The component never survives a navigation, so `roomParams` (computed via `useMemo`) is always fresh on mount. A `[router]` singleton as the sole `useMemo` dependency is therefore correct and intentional — do not flag it as a stale-dependency bug in this component.

Learnt from: ricardogarim
Repo: RocketChat/Rocket.Chat PR: 40100
File: apps/meteor/client/views/root/MainLayout/EmbeddedPreload.tsx:18-35
Timestamp: 2026-04-13T16:40:55.864Z
Learning: In Rocket.Chat's embedded mode (`?layout=embedded`), route changes are driven by the parent frame reloading the iframe URL, which causes a full remount of the React tree (including `EmbeddedPreload` at `apps/meteor/client/views/root/MainLayout/EmbeddedPreload.tsx`). The component never survives a navigation, so `roomParams` (computed via `useMemo`) is always fresh on mount. A `[router]` singleton as the sole `useMemo` dependency is therefore correct and intentional — do not flag it as a stale-dependency bug in this component.

Learnt from: ricardogarim
Repo: RocketChat/Rocket.Chat PR: 37205
File: ee/packages/federation-matrix/src/FederationMatrix.ts:296-301
Timestamp: 2025-10-28T16:53:42.761Z
Learning: In the Rocket.Chat federation-matrix integration (ee/packages/federation-matrix/), the createRoom method from rocket.chat/federation-sdk will support a 4-argument signature (userId, roomName, visibility, displayName) in newer versions. Code using this 4-argument call is forward-compatible with planned library updates and should not be flagged as an error.

Learnt from: dougfabris
Repo: RocketChat/Rocket.Chat PR: 39892
File: apps/meteor/client/views/room/contextualBar/Threads/Thread.tsx:150-155
Timestamp: 2026-03-27T14:52:56.865Z
Learning: In Rocket.Chat, there are two different `ModalBackdrop` components with different prop APIs. During review, confirm the import source: (1) `rocket.chat/fuselage` `ModalBackdrop` uses `ModalBackdropProps` based on `BoxProps` (so it supports `onClick` and other Box/DOM props) and does not have an `onDismiss` prop; (2) `rocket.chat/ui-client` `ModalBackdrop` uses a narrower props interface like `{ children?: ReactNode; onDismiss?: () => void }` and handles Escape keypress and outside mouse-up, and it does not forward arbitrary DOM props such as `onClick`. Flag mismatched props (e.g., `onDismiss` passed to the fuselage component or `onClick` passed to the ui-client component) and ensure the usage matches the correct component being imported.

Learnt from: Harxhit
Repo: RocketChat/Rocket.Chat PR: 39476
File: apps/meteor/server/methods/addAllUserToRoom.ts:0-0
Timestamp: 2026-03-09T18:39:21.178Z
Learning: In apps/meteor/server/methods/addAllUserToRoom.ts, the implementation uses a single cursor pass (Users.find(userFilter).batchSize(100)) that collects both the full user objects (collectedUsers: IUser[]) and their usernames (usernames: string[]) in one iteration. `beforeAddUserToRoom` is then called once with the full usernames batch (preserving batch-validation semantics), and the subsequent subscription/message processing loop iterates over the same stable `collectedUsers` array — no second DB query is made. This avoids any race condition between validation and processing while preserving the original batch-validation behavior.

Learnt from: juliajforesti
Repo: RocketChat/Rocket.Chat PR: 39545
File: apps/meteor/client/views/room/body/hooks/useHasNewMessages.ts:59-61
Timestamp: 2026-03-11T22:04:20.529Z
Learning: In `apps/meteor/client/views/room/body/hooks/useHasNewMessages.ts`, the `msg.u._id === uid` early-return in the `streamNewMessage` handler is intentional: the "New messages" indicator is designed to notify about messages from other users only. Self-sent messages — including those sent from a different session/device — are always skipped, by design. Do not flag this as a multi-session regression.

Learnt from: Dnouv
Repo: RocketChat/Rocket.Chat PR: 37057
File: packages/apps-engine/src/definition/accessors/IUserRead.ts:23-27
Timestamp: 2025-09-25T09:59:26.461Z
Learning: AppUserBridge.getUserRoomIds in apps/meteor/app/apps/server/bridges/users.ts always returns an array of strings by mapping subscription documents to room IDs, never undefined, even when user has no room subscriptions.

Learnt from: Dnouv
Repo: RocketChat/Rocket.Chat PR: 37057
File: packages/apps-engine/src/definition/accessors/IUserRead.ts:23-27
Timestamp: 2025-09-25T09:59:26.461Z
Learning: AppUserBridge.getUserRoomIds in apps/meteor/app/apps/server/bridges/users.ts always returns an array of strings (mapping subscription documents to room IDs), never undefined, even when user has no room subscriptions.

Learnt from: ahmed-n-abdeltwab
Repo: RocketChat/Rocket.Chat PR: 38913
File: packages/ddp-client/src/legacy/types/SDKLegacy.ts:34-34
Timestamp: 2026-02-25T20:10:16.987Z
Learning: In the RocketChat/Rocket.Chat monorepo, packages/ddp-client and apps/meteor do not use TypeScript project references. Module augmentations in apps/meteor (e.g., declare module 'rocket.chat/rest-typings') are not visible when compiling packages/ddp-client in isolation, which is why legacy SDK methods that depend on OperationResult types for OpenAPI-migrated endpoints must remain commented out.

Learnt from: MartinSchoeler
Repo: RocketChat/Rocket.Chat PR: 37557
File: apps/meteor/client/views/admin/ABAC/AdminABACRooms.tsx:115-116
Timestamp: 2025-11-27T17:56:26.050Z
Learning: In Rocket.Chat, the GET /v1/abac/rooms endpoint (implemented in ee/packages/abac/src/index.ts) only returns rooms where abacAttributes exists and is not an empty array (query: { abacAttributes: { $exists: true, $ne: [] } }). Therefore, in components consuming this endpoint (like AdminABACRooms.tsx), room.abacAttributes is guaranteed to be defined for all returned rooms, and optional chaining before calling array methods like .join() is sufficient without additional null coalescing.

Learnt from: sampaiodiego
Repo: RocketChat/Rocket.Chat PR: 37532
File: ee/packages/federation-matrix/src/FederationMatrix.ts:920-927
Timestamp: 2025-12-09T20:01:07.355Z
Learning: In Rocket.Chat's federation invite handling (ee/packages/federation-matrix/src/FederationMatrix.ts), when a user rejects an invite via federationSDK.rejectInvite(), the subscription cleanup happens automatically through an event-driven flow: Matrix emits a leave event back, which is processed by handleLeave() in ee/packages/federation-matrix/src/events/member.ts, and that function calls Room.performUserRemoval() to clean up the subscription. No explicit cleanup is needed in the reject branch of handleInvite() because the leave event handler takes care of it.
<!-- </add_learning>

Learnt from: tassoevan
Repo: RocketChat/Rocket.Chat PR: 38528
File: apps/meteor/client/startup/roles.ts:14-14
Timestamp: 2026-02-10T16:32:42.586Z
Learning: In Rocket.Chat's Meteor client code, DDP streams use EJSON and Date fields arrive as Date objects; do not manually construct new Date() in stream handlers (for example, in sdk.stream()). Only REST API responses return plain JSON where dates are strings, so implement explicit conversion there if needed. Apply this guidance to all TypeScript files under apps/meteor/client to ensure consistent date handling in DDP streams and REST responses.

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In the Rocket.Chat repository, do not reference Biome lint rules in code review feedback. Biome is not used even if biome.json exists; only reference Biome rules if there is explicit, project-wide usage documented. For TypeScript files, review lint implications without Biome guidance unless the project enables Biome rules.

Learnt from: gabriellsh
Repo: RocketChat/Rocket.Chat PR: 38778
File: packages/ui-voip/src/providers/useMediaSession.ts:192-192
Timestamp: 2026-02-26T19:25:44.063Z
Learning: In this repository (RocketChat/Rocket.Chat), Biome lint rules are not used even if a biome.json exists. When reviewing TypeScript files (e.g., packages/ui-voip/src/providers/useMediaSession.ts), ensure lint suggestions do not reference Biome-specific rules. Rely on general ESLint/TypeScript lint rules and project conventions instead.

Learnt from: amitb0ra
Repo: RocketChat/Rocket.Chat PR: 39647
File: apps/meteor/app/api/server/v1/users.ts:710-757
Timestamp: 2026-03-15T14:31:28.969Z
Learning: In RocketChat/Rocket.Chat, the `UserCreateParamsPOST` type in `apps/meteor/app/api/server/v1/users.ts` (migrated from `packages/rest-typings/src/v1/users/UserCreateParamsPOST.ts`) intentionally has `fields: string` (non-optional) and `settings?: IUserSettings` without a corresponding AJV schema entry. This is a pre-existing divergence carried over verbatim from the original rest-typings source (PR `#39647`). Do not flag this type/schema misalignment during the OpenAPI migration review — it is tracked as a separate follow-up fix.