How does Atlas prevent accidental edits in Unreal Engine during planning?

Atlas uses a dedicated plan agent with a strict permission set that denies all edit tools for your Unreal Engine C++ codebase, allowing writes only to a specific plan markdown file. This ensures a read-only design phase, preventing unintended modifications.

Can Atlas understand Unreal Engine's UCLASS macros and Build.cs files?

Yes, Atlas indexes code by AST declarations using tree-sitter, allowing it to understand `UCLASS`, `UPROPERTY`, `UFUNCTION` macros and correctly parse dependencies declared in `Build.cs` module rules, crucial for Unreal Engine development.

How does Atlas ensure my Unreal Engine code adheres to the Epic style guide?

After proposing code changes, Atlas can apply the engine's `.clang-format` to your C++ files, ensuring they match the Epic style guide before committing. This maintains consistent formatting across your Unreal Engine project.

What tools does Atlas use to research an Unreal Engine codebase?

Atlas provides `codebase_search` for semantic and keyword retrieval, `grep` for pattern matching, `read` for file inspection, and `lsp` for language server protocol features like definition lookup, all within your Unreal Engine project.

Is my Unreal Engine code kept private when using Atlas for planning?

Yes, Atlas can build its code index with local Ollama embeddings, keeping your Unreal Engine C++ code off third-party servers and ensuring privacy for your proprietary game development.

How does Atlas manage the transition from planning to implementing Unreal Engine changes?

The `plan_exit` tool facilitates this transition. Once your plan is complete, it prompts you to switch from the read-only plan agent to the build agent, which has permissions to modify your Unreal Engine project files and begin implementation.

Plan a Multi-File Change Before Editing in Unreal Engine with Atlas in 2026

Atlas empowers Unreal Engine developers in 2026 to design and review multi-file changes, such as refactoring UCLASS macros or adjusting Build.cs module rules, before any code is modified. It leverages tools like codebase_search and lsp to inform a detailed plan, ensuring alignment with the Unreal Automation Framework and clang-format standards.

How Atlas Plans Multi-File Changes in Unreal Engine C++

Atlas's dedicated plan agent allows Unreal Engine developers in 2026 to design complex multi-file changes without risk of accidental modification. This agent operates with a strict permission set, denying all edit tools except for writing to a specific plan markdown file, ensuring a read-only design phase for your C++ codebase.

The Atlas plan agent is specifically engineered to facilitate the design of multi-file changes within Unreal Engine C++ projects. When activated, its permissions are tightly controlled, explicitly denying any write operations to your source code, `Build.cs` files, or configuration. The only allowed write path is to a designated plan markdown file, typically located under `.atlas/plans/*.md`. This read-only environment ensures that research and design activities, such as analyzing `UCLASS` macros, `UPROPERTY` declarations, or `UFUNCTION` implementations, cannot inadvertently lead to code modifications. Atlas builds its code index using AST declarations via tree-sitter, providing a deep understanding of Unreal Engine's C++ structure, including the reflection system and module dependencies, which is crucial for accurate planning.

Concrete Commands and Files for Planning Unreal Engine Refactors

When planning a multi-file change in Unreal Engine, Atlas provides specific tools to interact with your project's C++ files and configuration. For instance, you can use `codebase_search` to locate all instances of a `UCLASS` macro across 10 modules, or `grep` to find specific string patterns within your `Source/` directories.

Atlas provides a suite of powerful tools for researching your Unreal Engine codebase during the planning phase. Use `codebase_search` to perform hybrid semantic and keyword retrieval, for example, `atlas codebase_search "UCLASS(Blueprintable)"` to find all blueprintable classes, or `atlas codebase_search "MyOldSystemComponent"` to locate references to a component slated for refactoring. The `grep` tool allows for precise pattern matching, such as `atlas grep "FMyDeprecatedStruct" Source/MyModule/Private/` to find specific struct usages. For detailed file inspection, `atlas read Source/MyGame/Public/MyActor.h` displays file content. The `lsp` tool integrates with your language server, enabling actions like `atlas lsp definition MyFunction` to jump directly to a function's definition, providing immediate context for complex Unreal Engine C++ code. All research findings are then documented in your plan markdown file, like `.atlas/plans/new_gameplay_feature.md`.

Ensuring Review and Safety for Unreal Engine Code Changes

Atlas prioritizes safety and review for Unreal Engine projects, especially when dealing with multi-file changes that could impact 100s of lines of C++ code. The plan agent's strict permissions prevent accidental edits, and the `plan_exit` tool initiates a clear handoff to the build agent only after explicit approval.

The planning workflow in Atlas is designed with multiple layers of safety for Unreal Engine development. The plan agent's read-only nature ensures that no accidental modifications occur during the design phase. Once your multi-file change plan is complete and documented in the markdown file, the `plan_exit` tool is invoked. This tool explicitly asks for confirmation: 'Plan at <path> is complete. Would you like to switch to the build agent and start implementing?' Answering 'Yes' initiates a controlled transition to the build agent, which then has the necessary permissions to propose and apply changes. Atlas computes a unified diff for every proposed file edit, surfacing it for your approval before writing to disk. This allows for meticulous review of every line of C++ code, `Build.cs` modification, or `Unreal Automation Framework` test addition, ensuring alignment with your team's standards and preventing regressions in your Unreal Engine project.

Integrating Atlas with Unreal Engine's C++ Toolchain

Atlas is designed to integrate deeply with the Unreal Engine C++ toolchain, understanding the nuances of `UCLASS` macros and `Build.cs` module rules. In 2026, Atlas ensures that any proposed change respects the Epic style guide by preparing for `clang-format` application and validating against the `Unreal Automation Framework`.

Atlas is specifically configured to understand the unique aspects of Unreal Engine C++ development. It recognizes and correctly interprets `UCLASS`, `UPROPERTY`, and `UFUNCTION` macros, treating them as core components of the Unreal Engine API. When proposing changes that involve module dependencies, Atlas correctly interacts with `Unreal Build Tool (Build.cs)`, ensuring that a new module dependency is added to the `Build.cs` file *before* any corresponding `#include` statements are introduced in C++ source files. This prevents common compilation errors that other C++ agents might miss. Furthermore, Atlas can generate Automation Spec tests and execute them through `UnrealEditor-Cmd` via the `Unreal Automation Framework`, behind a permission prompt, to validate the correctness of your multi-file changes. After code modifications are approved, Atlas can apply the engine's `.clang-format` configuration, guaranteeing that all new or modified C++ code adheres to the Epic style guide.

Step by step

01**Activate the Atlas plan agent:** Run `atlas agent switch plan` in your Unreal Engine project directory. This sets up a read-only environment, allowing writes only to `.atlas/plans/*.md`.
02**Research your Unreal Engine codebase:** Use `atlas codebase_search "UCLASS(BlueprintType)"` to find relevant classes, `atlas grep "MyOldFunction" Source/MyModule/` to locate specific code patterns, or `atlas lsp definition MyActor::BeginPlay` to navigate C++ definitions within your project.
03**Draft your multi-file change plan:** Write the detailed design into a plan markdown file, for example, `.atlas/plans/refactor_gameplay_system.md`. Document how `Build.cs` files will be updated for new module dependencies and how `UCLASS` macros will be modified.
04**Review the plan and prepare for implementation:** Once your plan is complete, call `atlas plan_exit`. Atlas will prompt: "Plan at .atlas/plans/refactor_gameplay_system.md is complete. Would you like to switch to the build agent and start implementing?"
05**Approve the switch to the build agent:** Answer "Yes" to the `plan_exit` prompt. Atlas will transition to the build agent, which now has permissions to modify your Unreal Engine C++ files, update `Build.cs`, and run `Unreal Automation Framework` tests.
06**Implement and validate changes:** The build agent will propose code changes, such as adding a module dependency in `Build.cs` or refactoring a `UFUNCTION`. Atlas will present a unified diff for approval before writing, and can run `Unreal Automation Framework` tests to validate the changes.
07**Format code to Epic style:** After changes are applied and approved, Atlas can apply the engine's `.clang-format` to ensure your C++ code adheres to the Epic style guide, maintaining consistency across your Unreal Engine project.

Frequently asked questions

How does Atlas prevent accidental edits in Unreal Engine during planning?: Atlas uses a dedicated plan agent with a strict permission set that denies all edit tools for your Unreal Engine C++ codebase, allowing writes only to a specific plan markdown file. This ensures a read-only design phase, preventing unintended modifications.
Can Atlas understand Unreal Engine's UCLASS macros and Build.cs files?: Yes, Atlas indexes code by AST declarations using tree-sitter, allowing it to understand `UCLASS`, `UPROPERTY`, `UFUNCTION` macros and correctly parse dependencies declared in `Build.cs` module rules, crucial for Unreal Engine development.
How does Atlas ensure my Unreal Engine code adheres to the Epic style guide?: After proposing code changes, Atlas can apply the engine's `.clang-format` to your C++ files, ensuring they match the Epic style guide before committing. This maintains consistent formatting across your Unreal Engine project.
What tools does Atlas use to research an Unreal Engine codebase?: Atlas provides `codebase_search` for semantic and keyword retrieval, `grep` for pattern matching, `read` for file inspection, and `lsp` for language server protocol features like definition lookup, all within your Unreal Engine project.
How does Atlas handle testing for Unreal Engine changes?: Atlas can write Automation Spec tests and run them through `UnrealEditor-Cmd` via the `Unreal Automation Framework`, behind a permission prompt, to validate proposed changes and ensure stability in your Unreal Engine project.
Is my Unreal Engine code kept private when using Atlas for planning?: Yes, Atlas can build its code index with local Ollama embeddings, keeping your Unreal Engine C++ code off third-party servers and ensuring privacy for your proprietary game development.
How does Atlas manage the transition from planning to implementing Unreal Engine changes?: The `plan_exit` tool facilitates this transition. Once your plan is complete, it prompts you to switch from the read-only plan agent to the build agent, which has permissions to modify your Unreal Engine project files and begin implementation.

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