How does Atlas ensure my Echo module's behavior doesn't change during refactoring?

Atlas pins behavior by running `go test (httptest)` with the `bash` tool to establish a green baseline before any changes. It then re-runs these tests after each structural modification to immediately detect regressions in your Echo service.

Can Atlas help me identify all callers of an Echo handler I want to refactor?

Yes, Atlas uses the `lsp` tool's `findReferences` operation on each exported symbol to enumerate every callsite. This ensures you identify all dependencies of your Echo handler, including `echo.Group` routes and custom binders.

What if a file drifts while Atlas is applying a patch to my Echo code?

Atlas's `apply_patch` tool anchors on context lines and `old_lines`. If the file has drifted, it will fail with `Failed to find context`, preventing unintended changes to your Echo codebase and ensuring safety.

How does Atlas integrate with standard Echo development tools like `gofumpt`?

Atlas connects to Model Context Protocol servers and exposes their tools. After making edits, Atlas can run `gofumpt` over the touched packages, behind a permission prompt, to ensure consistent formatting across your Echo project.

Is Atlas compatible with my existing `go.mod` setup for Echo projects?

Yes, you run Atlas in a module whose `go.mod` requires `github.com/labstack/echo/v4`. Atlas integrates direct with your existing Go module structure and toolchain.

How does Atlas ensure I review all changes before they are committed to my Echo project?

Atlas computes a unified diff for every file edit and surfaces it for approval before writing. It also reads `git` branches, status, and diffs, and can stage and create commits on your behalf, giving you full control over your Echo codebase.

Refactor a legacy module in Echo with Atlas in 2026

Atlas helps Echo developers in 2026 refactor legacy modules by mapping public surfaces with the `lsp` tool, pinning behavior with `go test (httptest)` via `bash`, and applying structural changes safely with `apply_patch`, ensuring no breaking changes to callers or the Echo service's behavior.

How Atlas Maps Echo Module Public Surfaces and Callers

Atlas helps Echo developers in 2026 understand legacy module boundaries by mapping public surfaces with the `lsp` tool's `documentSymbol` operation. This initial step identifies all exported functions, types, and variables, providing a comprehensive overview of the module's public API, often revealing 10+ key symbols.

To safely refactor a legacy Echo module, the first critical step is to fully understand its public contract. Atlas achieves this by leveraging its `lsp` tool, specifically the `documentSymbol` operation, which indexes code by AST declarations using tree-sitter. This allows Atlas to precisely identify all exported functions, methods, types, and variables within your Echo module. Once the public surface is mapped, Atlas then uses `lsp`'s `findReferences` operation on each exported symbol. This enumerates every callsite across your codebase, including interactions with `echo.Group` routes, custom binders, and `HTTPErrorHandler` implementations. This comprehensive mapping ensures that Atlas has a complete picture of how the module is used, preventing silent breakage at unknown callsites during the refactoring process. The information gathered informs the subsequent steps, ensuring that all dependencies are accounted for.

Pinning Echo Module Behavior with `go test (httptest)`

Before any structural changes, Atlas ensures the existing behavior of an Echo module is pinned by running `go test (httptest)` to establish a green baseline. This critical step, performed in 2026, guarantees that subsequent refactoring efforts do not introduce regressions, with 100% test coverage being the ideal target for legacy code.

A core principle of safe refactoring is to 'pin behavior first.' For Echo modules, Atlas accomplishes this by using the `bash` tool to execute your existing test suite. Specifically, Atlas runs `go test (httptest)`, which is the standard Go testing framework augmented for HTTP handlers, making it perfect for Echo services. Atlas records the output of these tests, establishing a 'green baseline.' This baseline serves as the immutable contract for the module's behavior. After each incremental structural change applied by Atlas, the `go test (httptest)` suite is re-run immediately. This rapid feedback loop ensures that any unintended behavioral changes are caught and addressed at the earliest possible moment, preventing a cascade of errors and maintaining the integrity of your Echo application.

Applying Structural Refactors to Echo Code with `apply_patch`

Atlas applies structural changes to Echo modules using the `apply_patch` tool, which anchors on context lines and refuses to apply against a drifted file. This method, crucial for safe refactoring in 2026, ensures that each modification is precise and prevents unintended alterations to the surrounding 5-10 lines of code.

Once the public surface is mapped and behavior is pinned, Atlas proceeds with structural refactoring using its `apply_patch` tool. This tool is designed for robust and precise code modifications. Unlike simple line-based edits, `apply_patch` anchors each hunk on context lines and `old_lines`. This means that if the target file has drifted or been modified by another process since Atlas last read it, `apply_patch` will fail with a `Failed to find context` error. This mechanism is a vital safety feature, preventing Atlas from applying changes to an outdated or unexpected version of your Echo source code. Atlas computes a unified diff for every file edit, which is then surfaced for your approval before any changes are written to disk. This granular control ensures that every modification to your Echo handlers, middleware, or custom binders is explicit and reviewed.

Verifying Echo Callers and Reviewing Changes with Atlas

Atlas ensures no Echo callers are broken during refactoring by tracking remaining callsites in a `todowrite` list and presenting a unified diff for every file edit. This rigorous review process, essential for complex projects in 2026, provides a clear audit trail for all 1-5 files modified in a typical refactor.

Maintaining the integrity of your Echo application's callers is paramount during a refactor. Atlas addresses this by continuously tracking the migration of callsites. After identifying all references with `lsp findReferences`, Atlas uses its `todowrite` tool to maintain a list of remaining callsites that still need to be updated. This ensures that a partially migrated Echo module cannot be mistaken for a finished one, providing a clear roadmap to completion. For every file edit, Atlas computes and surfaces a unified diff for your approval, allowing you to review changes to `echo.NewHTTPError` calls or custom `Validator` implementations. Atlas also integrates with your `git` workflow, reading branches, status, and diffs, and can stage and create commits on your behalf. Finally, to maintain code quality, Atlas can run `gofumpt` over the touched packages, behind a permission prompt, ensuring your refactored Echo code adheres to standard Go formatting.

Step by step

01Run `atlas` in your Echo module's root directory, ensuring its `go.mod` file requires `github.com/labstack/echo/v4`.
02Use Atlas's `lsp` tool with the `documentSymbol` operation to map the public surface of the legacy Echo module.
03For each identified exported symbol, use Atlas's `lsp` tool with `findReferences` to enumerate all existing callers within your Echo codebase.
04Pin the module's current behavior by running existing tests with `bash` and `go test (httptest)`, recording the green baseline.
05Apply structural changes to the Echo module's source code using Atlas's `apply_patch` tool, which anchors on context lines for safety.
06After each `apply_patch` hunk successfully lands, immediately re-run `bash` with `go test (httptest)` to verify behavior and detect regressions.
07Track any remaining callsites that still need migration in a `todowrite` list to ensure a complete refactor of the Echo module.
08Review the unified diff for every file edit presented by Atlas and explicitly approve changes before they are written to your Echo project.
09Let Atlas run `gofumpt` over the touched packages, behind a permission prompt, to ensure consistent Go code formatting.
10Use Atlas to stage the refactored Echo files and create a `git` commit on your behalf, documenting the changes.

Frequently asked questions

How does Atlas ensure my Echo module's behavior doesn't change during refactoring?: Atlas pins behavior by running `go test (httptest)` with the `bash` tool to establish a green baseline before any changes. It then re-runs these tests after each structural modification to immediately detect regressions in your Echo service.
Can Atlas help me identify all callers of an Echo handler I want to refactor?: Yes, Atlas uses the `lsp` tool's `findReferences` operation on each exported symbol to enumerate every callsite. This ensures you identify all dependencies of your Echo handler, including `echo.Group` routes and custom binders.
What if a file drifts while Atlas is applying a patch to my Echo code?: Atlas's `apply_patch` tool anchors on context lines and `old_lines`. If the file has drifted, it will fail with `Failed to find context`, preventing unintended changes to your Echo codebase and ensuring safety.
How does Atlas integrate with standard Echo development tools like `gofumpt`?: Atlas connects to Model Context Protocol servers and exposes their tools. After making edits, Atlas can run `gofumpt` over the touched packages, behind a permission prompt, to ensure consistent formatting across your Echo project.
How does Atlas help me track the progress of a large Echo module refactor?: Atlas tracks remaining callsites in a `todowrite` list. This ensures that a partially migrated Echo module cannot be mistaken for a finished one, providing a clear roadmap for completion and preventing silent breakage.
Is Atlas compatible with my existing `go.mod` setup for Echo projects?: Yes, you run Atlas in a module whose `go.mod` requires `github.com/labstack/echo/v4`. Atlas integrates direct with your existing Go module structure and toolchain.
How does Atlas ensure I review all changes before they are committed to my Echo project?: Atlas computes a unified diff for every file edit and surfaces it for approval before writing. It also reads `git` branches, status, and diffs, and can stage and create commits on your behalf, giving you full control over your Echo codebase.

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