How do I refactor a Symfony controller into an injected service with Atlas?

Atlas can assist by first mapping the controller's public methods using lsp documentSymbol, then finding all references with lsp findReferences. You can then ask Atlas to move the logic into a new service, update config/services.yaml for autowiring, and apply changes with apply_patch, validating each step with PHPUnit (WebTestCase).

Can Atlas help me update Doctrine entity mappings during a Symfony refactor?

Yes, Atlas can read your Doctrine entity mappings. You can ask Atlas to modify an entity, then have it run bin/console doctrine:migrations:diff to generate the SQL. Atlas will show you the generated SQL for approval before any database changes are applied, ensuring data integrity.

How does Atlas prevent breaking existing routes or services in Symfony?

Atlas prevents breakage by first mapping all public symbols and their callers using lsp findReferences. It then applies changes incrementally with apply_patch, which requires context matching. Crucially, Atlas re-runs your PHPUnit (WebTestCase) suite after each change, immediately flagging any broken routes or services.

What if my Symfony codebase has drifted since Atlas generated a patch?

Atlas's apply_patch tool is designed for this. If the target file has drifted, apply_patch will fail with a "Failed to find context" error. This prevents the patch from being applied incorrectly, ensuring code integrity and requiring you to re-evaluate the change.

How does Atlas integrate with Symfony's Composer and PHP-CS-Fixer?

Atlas integrates direct by using its bash tool to execute standard Symfony commands. You can run composer install or composer update directly, and after refactoring, have Atlas run vendor/bin/php-cs-fixer fix over the diff to maintain code standards, all within the terminal.

Can Atlas help me add PHPUnit WebTestCase coverage to a legacy Symfony module?

Yes, you can ask Atlas to add PHPUnit WebTestCase coverage for a specific legacy Symfony module. Atlas can draft new test cases, apply them with apply_patch, and then run bin/phpunit to verify the new coverage and ensure the module's behavior is adequately tested.

How does Atlas ensure I approve every change to my Symfony project?

Atlas operates with explicit user approval at multiple stages. It drafts plans in a read-only agent, asks for permission before executing tools, and computes a unified diff for every file edit, which you must approve before it's written. This granular control ensures you oversee all modifications to your Symfony codebase.

Refactor a Legacy Module in Symfony with Atlas in 2026

Refactoring a legacy module in Symfony without breaking existing functionality or callers is a critical task, and Atlas streamlines this process by leveraging your existing PHPUnit (WebTestCase) suite, Composer dependencies, and PHP-CS-Fixer standards. Atlas maps the module's public surface, pins behavior with tests, and applies structural changes with precise, approved patches, ensuring a safe transition for your Symfony application in 2026.

How does Atlas map a Symfony module's public surface?

Atlas identifies the public surface of a Symfony module by using the lsp tool's documentSymbol operation, providing a comprehensive view of all 2026-era exported symbols. This initial mapping is crucial for understanding the module's external contract before any refactoring begins.

Atlas begins a refactoring task by thoroughly understanding the module's external interface. It employs the lsp tool's documentSymbol operation to enumerate all public classes, methods, and properties within your Symfony bundle or service. This process is not limited to simple file scanning; Atlas leverages its AST declarations index, built with tree-sitter, to precisely identify every callable entry point. For instance, in a Symfony controller, Atlas would list all public action methods, or for a service, all public methods exposed for autowiring. This detailed map forms the foundation for identifying all potential callers, ensuring that no part of the module's public contract is overlooked during the restructuring process. Atlas can then use findReferences on each of these identified symbols to build a complete call graph.

How to pin Symfony module behavior before refactoring?

Before any structural changes, Atlas pins the existing behavior of your Symfony module by running your PHPUnit (WebTestCase) suite, establishing a green baseline. This critical step ensures that the module's functionality remains identical, with 0 regressions, throughout the refactoring process.

The most significant risk in refactoring a legacy Symfony module is introducing silent regressions. Atlas mitigates this by first establishing a robust behavioral baseline. It uses the bash tool to execute your existing PHPUnit (WebTestCase) suite, typically via bin/phpunit. Atlas records the output, ensuring all tests pass before any modifications are made. This "green baseline" serves as the immutable contract for the module's behavior. After each incremental change, Atlas re-runs these same tests, immediately flagging any deviation from the expected outcome. This iterative testing approach, rather than a single run at the end, provides continuous validation and confidence that the refactoring maintains the module's original functionality, whether it involves moving a controller, adjusting a service, or modifying a Doctrine entity.

Applying Structural Changes to Symfony Code with Atlas

Atlas applies structural changes to Symfony code using the apply_patch tool, which anchors on context lines and refuses to apply against a drifted file, ensuring precise modifications. This method prevents accidental overwrites and maintains code integrity across 2026 development cycles.

When restructuring a Symfony module, Atlas employs the apply_patch tool for all code modifications. This tool is designed for safety and precision: it generates a unified diff for every proposed change and requires explicit approval before writing to disk. Crucially, apply_patch anchors each hunk on its context lines and old_lines. If the target file has drifted since the patch was generated (e.g., due to concurrent development), apply_patch will fail with a "Failed to find context" error, preventing a potentially destructive merge. This mechanism is vital for refactoring complex Symfony components like controllers, services, or Doctrine repositories, where even minor changes can have cascading effects. Atlas also tracks remaining callsites in a todowrite list, ensuring that a partially migrated module is never mistaken for a finished one, providing a clear path to completion.

Ensuring Safety and Review in Symfony Refactoring with Atlas

Atlas ensures safety and review in Symfony refactoring through multiple permission-gated steps and explicit user approvals, preventing unintended changes. Every Atlas tool call is permission-gated against allow, ask, and deny rules, providing 100% control over modifications to your codebase.

Safety and transparency are paramount when refactoring critical Symfony components. Atlas integrates several layers of review and approval into its workflow. Before any tool call runs, it's permission-gated against user-defined allow, ask, and deny rules. This means Atlas will explicitly ask for permission before, for example, running bin/console doctrine:migrations:diff or applying a patch to a core service. Furthermore, Atlas drafts a plan in a read-only plan agent and seeks approval before switching to a build agent to execute changes. For every file edit, Atlas computes a unified diff and surfaces it for approval, allowing developers to review every line change before it's written. Atlas also snapshots file changes as git patches, enabling easy diffing and rolling back of edits, providing a robust safety net for complex Symfony refactors.

Managing Callers and Dependencies in Symfony Refactoring

Atlas manages callers and dependencies during Symfony refactoring by exhaustively enumerating every callsite using the lsp tool's findReferences operation. This ensures that 100% of dependent code is identified and updated, preventing silent breakage across your application.

A major challenge in refactoring a legacy Symfony module is identifying and updating all its callers. Atlas addresses this by leveraging the lsp tool's findReferences operation. After mapping the module's public surface, Atlas systematically queries for all references to each exported symbol. This includes references within controllers, services, Twig templates, or even other bundles. Atlas then tracks these identified callsites in a todowrite list. As the refactoring progresses and symbols are moved or renamed, Atlas guides the developer through updating each callsite. This meticulous approach ensures that no caller is left pointing to a non-existent or incorrect symbol, preventing runtime errors and maintaining the integrity of your Symfony application's dependency graph. This is particularly useful when moving a fat controller into an injected service or restructuring a complex Doctrine entity.

Step by step

01Map the Symfony module's public surface: Use Atlas's lsp tool with the documentSymbol operation to identify all public classes, methods, and properties within your target Symfony bundle or service. For each identified symbol, use lsp findReferences to enumerate every callsite across your application, including controllers, services, and configuration files.
02Pin existing behavior with PHPUnit (WebTestCase): Execute your current PHPUnit (WebTestCase) suite using Atlas's bash tool (e.g., bash bin/phpunit) to establish a green baseline. Record this successful test run as the expected behavior before making any changes to the legacy Symfony module.
03Restructure the module incrementally with apply_patch: Draft and apply structural changes to your Symfony code using Atlas's apply_patch tool. Atlas will present a unified diff for approval. Ensure apply_patch succeeds, as it will fail with "Failed to find context" if the file has drifted, preventing accidental overwrites.
04Re-run PHPUnit (WebTestCase) after each change: Immediately after each successful apply_patch operation, re-run your PHPUnit (WebTestCase) suite using bash bin/phpunit. This continuous validation ensures that each incremental change maintains the module's original behavior and prevents regressions in your Symfony application.
05Track and update remaining callsites with todowrite: Use Atlas's todowrite tool to track all identified callsites that still need migration. As you update references in controllers, services, or configuration files (e.g., config/services.yaml), mark them off the list, ensuring a complete and verifiable refactor of your Symfony module.
06Format code with PHP-CS-Fixer and commit: Once the refactoring is complete and all tests pass, use Atlas's bash tool to run PHP-CS-Fixer over the modified files (e.g., bash vendor/bin/php-cs-fixer fix --diff --config=.php-cs-fixer.dist.php). Review the diff, then use Atlas to stage and create a commit, capturing the refactored Symfony module.

Frequently asked questions

How do I refactor a Symfony controller into an injected service with Atlas?: Atlas can assist by first mapping the controller's public methods using lsp documentSymbol, then finding all references with lsp findReferences. You can then ask Atlas to move the logic into a new service, update config/services.yaml for autowiring, and apply changes with apply_patch, validating each step with PHPUnit (WebTestCase).
Can Atlas help me update Doctrine entity mappings during a Symfony refactor?: Yes, Atlas can read your Doctrine entity mappings. You can ask Atlas to modify an entity, then have it run bin/console doctrine:migrations:diff to generate the SQL. Atlas will show you the generated SQL for approval before any database changes are applied, ensuring data integrity.
How does Atlas prevent breaking existing routes or services in Symfony?: Atlas prevents breakage by first mapping all public symbols and their callers using lsp findReferences. It then applies changes incrementally with apply_patch, which requires context matching. Crucially, Atlas re-runs your PHPUnit (WebTestCase) suite after each change, immediately flagging any broken routes or services.
What if my Symfony codebase has drifted since Atlas generated a patch?: Atlas's apply_patch tool is designed for this. If the target file has drifted, apply_patch will fail with a "Failed to find context" error. This prevents the patch from being applied incorrectly, ensuring code integrity and requiring you to re-evaluate the change.
How does Atlas integrate with Symfony's Composer and PHP-CS-Fixer?: Atlas integrates direct by using its bash tool to execute standard Symfony commands. You can run composer install or composer update directly, and after refactoring, have Atlas run vendor/bin/php-cs-fixer fix over the diff to maintain code standards, all within the terminal.
Can Atlas help me add PHPUnit WebTestCase coverage to a legacy Symfony module?: Yes, you can ask Atlas to add PHPUnit WebTestCase coverage for a specific legacy Symfony module. Atlas can draft new test cases, apply them with apply_patch, and then run bin/phpunit to verify the new coverage and ensure the module's behavior is adequately tested.
How does Atlas ensure I approve every change to my Symfony project?: Atlas operates with explicit user approval at multiple stages. It drafts plans in a read-only agent, asks for permission before executing tools, and computes a unified diff for every file edit, which you must approve before it's written. This granular control ensures you oversee all modifications to your Symfony codebase.

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