How does Atlas handle Dart null safety migrations during refactoring?

Atlas can assist with Dart null safety migrations. You can ask Atlas to migrate your code to null safety, and it will propose changes, presenting a unified diff for your review and approval before applying them to your Dart files.

Can Atlas refactor across multiple Dart packages?

Yes, Atlas is designed to pair with Dart across `pub` packages. It can read your libraries and `pub` dependencies, allowing it to understand and refactor code that spans multiple packages within your project's `pubspec.yaml` defined structure.

What Dart tools does Atlas integrate with for refactoring?

Atlas integrates directly with core Dart tools. It uses `dart test` for running tests, `pub` for package management, and `dart format` for code formatting, ensuring a native Dart developer experience within your terminal.

How does Atlas ensure my Dart code stays private during refactoring?

Atlas prioritizes privacy by allowing you to build its code index with local Ollama embeddings, keeping your Dart code off third-party servers. All tool calls are permission-gated, and edits require explicit approval, ensuring your code remains secure.

What if Atlas's patch fails to apply to my Dart file?

Atlas's `apply_patch` tool is designed for safety. If the target Dart file has drifted from the expected state, `apply_patch` will fail with "Failed to find context," preventing unintended changes and prompting you to review the file's current state before proceeding.

Can Atlas help me add tests to a legacy Dart module before refactoring?

Yes, Atlas can help you add tests. You can ask Atlas to add tests to your legacy Dart module, and it will draft a plan and propose new test files or modifications, which you can review and approve before running `dart test` to establish a baseline.

How does Atlas manage Dart dependencies during refactoring?

Atlas reads your `pubspec.yaml` and `pub` dependencies to understand your Dart project's structure. While it doesn't directly manage `pub` dependencies, it uses this context to inform its refactoring decisions and ensure proposed changes are valid within your dependency graph.

Refactor a Legacy Dart Module with Atlas in 2026

Atlas empowers Dart developers in 2026 to safely refactor legacy modules by mapping public surfaces with the `lsp` tool, pinning behavior with `dart test`, and applying structural changes with `apply_patch`, ensuring no breaking changes to callers or unintended side effects.

How to map a Dart module's public API and find all callers?

Atlas helps Dart developers in 2026 map a module's public surface and enumerate all callers by leveraging the `lsp` tool's `documentSymbol` and `findReferences` operations. This ensures a complete understanding of the module's external dependencies before any refactoring begins.

Before initiating any refactoring of a legacy Dart module, understanding its public API and all its callers is paramount to prevent silent breakage. Atlas achieves this by integrating with the Language Server Protocol (LSP) through its `lsp` tool. First, you can use `atlas lsp documentSymbol <path/to/module.dart>` to identify all exported symbols within your Dart module, such as classes, functions, and variables defined in files like `lib/src/legacy_module.dart`. Once these symbols are identified, Atlas can then execute `atlas lsp findReferences <path/to/module.dart> <symbol_name>` for each public symbol. This operation meticulously enumerates every single callsite across your entire Dart project, including those in other `pub` packages. This comprehensive mapping ensures that when you restructure the module, Atlas has a complete list of all locations that might be affected, allowing for a systematic and safe migration process.

How does Atlas ensure a Dart module's behavior doesn't change during refactoring?

Before any structural changes, Atlas pins a Dart module's existing behavior by running `dart test` with the `bash` tool and recording a green baseline. This crucial first step, performed in 2026, provides an immediate feedback loop for every subsequent modification, ensuring behavioral integrity.

Maintaining the existing behavior of a legacy Dart module is a core requirement during refactoring. Atlas addresses this by strictly adhering to a 'pin behavior first' principle. Using the `bash` tool, Atlas executes your project's `dart test` command, which is the standard Dart test runner. This establishes a 'green baseline' - a verified state where all existing tests pass. This baseline is critical because after each incremental change applied during the refactoring process, Atlas will re-run `dart test` via `atlas bash "dart test"`. If any test fails, it immediately signals a behavioral regression, allowing the developer to identify and rectify the issue before proceeding. This iterative testing approach, rather than a single test run at the end, significantly reduces the risk of introducing subtle bugs and ensures the refactored Dart code behaves identically to its original version.

How does Atlas apply structural changes to Dart code without breaking it?

Atlas applies structural changes to Dart code using the `apply_patch` tool, which anchors on context lines and refuses to apply against a drifted file. This ensures that every modification, even in a large 2026 codebase, is precise and prevents unintended changes, maintaining code integrity.

Restructuring Dart code safely is a primary concern during refactoring. Atlas employs its `apply_patch` tool for this purpose, which is designed with robust safety mechanisms. When Atlas proposes a change, it generates a unified diff, which is then presented to the developer for approval. The `apply_patch` tool doesn't just blindly overwrite files; it seeks each hunk's context and old_lines. If the target Dart file has drifted from the expected state - meaning the context lines or old lines specified in the patch no longer match the current file content - `apply_patch` will fail with a "Failed to find context" error. This prevents the application of a patch to an outdated or modified file, thereby avoiding corrupted code. Furthermore, every Atlas tool call is permission-gated, and every file edit results in a unified diff that is surfaced for explicit approval before writing, giving the Dart developer full control and visibility over all changes to their `lib/` and `test/` directories.

How to track refactoring progress in a Dart project with Atlas?

Atlas helps Dart developers track refactoring progress using the `todowrite` tool, ensuring a partially migrated module is never mistaken for a finished one. This systematic approach, vital for complex projects in 2026, maintains clarity and prevents incomplete work from being deployed.

Refactoring a large legacy Dart module can be a multi-step process, and keeping track of remaining work is essential. Atlas provides the `todowrite` tool specifically for this purpose. As you identify callsites that need migration or specific parts of the module that still require restructuring, you can use `atlas todowrite "Migrate usage of old_function in package:my_app/lib/caller.dart"` to add these items to a persistent to-do list. This list serves as a clear, actionable roadmap, ensuring that a partially migrated module cannot be mistaken for a finished one. By systematically checking off items from this list, Dart developers can confidently track their progress, ensuring that all identified refactoring tasks are completed before the module is considered fully refactored and ready for deployment.

What safety features does Atlas offer for refactoring Dart code?

Atlas provides multiple layers of safety for Dart refactoring, including permission-gated tool calls and a read-only plan agent before switching to a build agent. Every file edit generates a unified diff for approval, ensuring developers in 2026 maintain full control over changes to their Dart codebase.

Atlas is built with a strong emphasis on safety and developer control, especially crucial when dealing with legacy Dart code. All Atlas tool calls, including `lsp`, `apply_patch`, and `bash`, are permission-gated against allow, ask, and deny rules, ensuring that no action is taken without explicit or pre-approved consent. Atlas drafts a plan in a read-only plan agent first, asking for approval before it switches to a build agent to execute changes. For every proposed file edit, Atlas computes and surfaces a unified diff, allowing the Dart developer to review and approve or reject the changes before they are written to disk. Atlas also reads `git` branches, status, and diffs, and can stage and create commits on your behalf, providing robust version control integration. Furthermore, Atlas snapshots file changes as `git` patches, enabling easy diffing and rolling back of edits, adding another layer of safety to your Dart refactoring workflow.

Step by step

011: Identify the public surface of the Dart module: Use Atlas's `lsp` tool to map the module's public API. For example, `atlas lsp documentSymbol lib/src/legacy_module.dart` then `atlas lsp findReferences lib/src/legacy_module.dart MyPublicClass` for each symbol.
022: Establish a green test baseline: Before any changes, run the existing Dart tests to confirm current behavior. Execute `atlas bash "dart test"` and record the output to ensure a consistent baseline.
033: Apply structural changes incrementally: Use Atlas's `apply_patch` tool to restructure the Dart code. For instance, `atlas apply_patch --file lib/src/legacy_module.dart --patch <patch_content>`. Atlas will present a unified diff for approval.
044: Verify behavior after each change: Immediately re-run the Dart tests after each `apply_patch` operation to catch regressions. Use `atlas bash "dart test"` to ensure no behavioral changes are introduced.
055: Track remaining callsites for migration: Use Atlas's `todowrite` tool to list any remaining callsites that need migration or further refactoring. Example: `atlas todowrite "Migrate usage of old_function in package:my_app/lib/caller.dart"`.
066: Format Dart code: Ensure consistency with the standard Dart formatter after changes. Run `atlas bash "dart format lib/src/legacy_module.dart"`.
077: Commit changes: Use Atlas's `git` integration to stage and commit the refactored Dart code. For example, `atlas git add lib/src/legacy_module.dart` followed by `atlas git commit -m "Refactor: Restructured legacy_module.dart"`.

Frequently asked questions

How does Atlas handle Dart null safety migrations during refactoring?: Atlas can assist with Dart null safety migrations. You can ask Atlas to migrate your code to null safety, and it will propose changes, presenting a unified diff for your review and approval before applying them to your Dart files.
Can Atlas refactor across multiple Dart packages?: Yes, Atlas is designed to pair with Dart across `pub` packages. It can read your libraries and `pub` dependencies, allowing it to understand and refactor code that spans multiple packages within your project's `pubspec.yaml` defined structure.
What Dart tools does Atlas integrate with for refactoring?: Atlas integrates directly with core Dart tools. It uses `dart test` for running tests, `pub` for package management, and `dart format` for code formatting, ensuring a native Dart developer experience within your terminal.
How does Atlas ensure my Dart code stays private during refactoring?: Atlas prioritizes privacy by allowing you to build its code index with local Ollama embeddings, keeping your Dart code off third-party servers. All tool calls are permission-gated, and edits require explicit approval, ensuring your code remains secure.
What if Atlas's patch fails to apply to my Dart file?: Atlas's `apply_patch` tool is designed for safety. If the target Dart file has drifted from the expected state, `apply_patch` will fail with "Failed to find context," preventing unintended changes and prompting you to review the file's current state before proceeding.
Can Atlas help me add tests to a legacy Dart module before refactoring?: Yes, Atlas can help you add tests. You can ask Atlas to add tests to your legacy Dart module, and it will draft a plan and propose new test files or modifications, which you can review and approve before running `dart test` to establish a baseline.
How does Atlas manage Dart dependencies during refactoring?: Atlas reads your `pubspec.yaml` and `pub` dependencies to understand your Dart project's structure. While it doesn't directly manage `pub` dependencies, it uses this context to inform its refactoring decisions and ensure proposed changes are valid within your dependency graph.

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