snapshot of https://github.com/mattermost/mattermost.git (master, 2026-09-16; blobs > 131072B omitted)

server/channels/app/doc.go

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+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+/*
+Package app provides the business logic layer for Mattermost Channels.
+
+This package serves as the core business logic layer that sits between the API layer (api4)
+and the data access layer (store). It contains the primary application logic for all
+Mattermost functionality including user management, channel operations, post handling,
+notifications, authentication, authorization, and integrations.
+
+# Architecture
+
+The app package follows a layered architecture pattern:
+
+	┌─────────────────────────────────────────────────────────────────┐
+	│                       API Layer (api4)                         │
+	├─────────────────────────────────────────────────────────────────┤
+	│                    Business Logic (app)                        │
+	├─────────────────────────────────────────────────────────────────┤
+	│                     Data Access (store)                        │
+	└─────────────────────────────────────────────────────────────────┘
+
+# Core Components
+
+## App Structure
+
+The App struct is the main entry point for business logic operations. It is a pure
+functional component that does not hold state, constructed per request and provides
+access to business logic methods through its association with the Channels struct.
+
+## Server
+
+The Server struct manages the HTTP server, routing, middleware, and service lifecycle.
+It coordinates between platform services, manages enterprise features, handles
+clustering, and provides the runtime environment for the application.
+
+## Channels
+
+The Channels struct contains all channels-related state and enterprise interface
+implementations. It manages plugins, file storage, image processing, and coordinates
+various enterprise features like compliance, LDAP, and SAML.
+
+## Platform Service
+
+The platform service handles non-entity related functionalities required by the
+application including database access, configuration management, caching, licensing,
+metrics, and search engines.
+
+# Design Patterns
+
+## Request Context Pattern
+All business logic methods accept a request.CTX parameter for request-scoped
+logging, tracing, and cancellation.
+
+## Interface Segregation
+Enterprise features are accessed through interfaces in the einterfaces package,
+allowing for modular enterprise functionality.
+
+## Dependency Injection
+Services and dependencies are injected through the Server and Channels structs,
+enabling testability and modularity.
+
+## Event-Driven Architecture
+The application uses WebSocket events and plugin hooks for real-time updates
+and extensibility.
+
+# Key Responsibilities
+
+  - Business logic: Core application rules and workflows
+  - Data orchestration: Coordinate between multiple stores and services
+  - External integrations: Third-party service calls and API interactions
+  - Cache management: Handle cache invalidation and updates
+  - Event handling: Trigger notifications, webhooks, and background jobs
+
+# Error Handling
+
+The package uses model.AppError for consistent error handling across the
+application. Errors include structured information for logging, user
+messages, and HTTP status codes.
+
+This package is central to the Mattermost server architecture and provides
+the foundation for all collaboration features in the platform.
+*/
+package app