# Onboard to an Unfamiliar Echo Codebase in 2026 with Atlas > Atlas helps Echo developers in 2026 build a mental model of new codebases by semantically searching, analyzing `go mod` dependencies, and understanding `echo.Group` routes. To build a working mental model of an unfamiliar Echo repository without reading every file, Atlas in 2026 leverages semantic search, `go mod` for dependency insights, and `go test (httptest)` for behavioral understanding, allowing you to quickly grasp the codebase's structure and logic. This approach helps Echo developers efficiently navigate new projects by focusing on meaning and key architectural components rather than line-by-line review. ## Key takeaways - Atlas uses semantic search to find Echo-specific concepts like `echo.Group` routes and `echo.NewHTTPError` usage. - `glob` and `go mod` quickly reveal an Echo project's package structure and `github.com/labstack/echo/v4` dependencies. - The `explore` subagent safely sweeps Echo codebases in read-only mode to find custom binders or middleware. - Atlas ensures safety with permission-gated tools and unified diffs for all proposed changes to Echo files. - `todowrite` helps track open questions and insights about an unfamiliar Echo codebase across sessions. ## How does Atlas find relevant Echo code without reading every file? Atlas in 2026 uses `codebase_search` to find relevant Echo code by meaning, not just filenames, allowing you to pinpoint specific logic like authentication or error handling within seconds. This tool queries a semantic index built from AST declarations, ensuring precise results without scanning 100% of the repository. When faced with an unfamiliar Echo codebase, the first challenge is often locating where core functionalities reside. Atlas addresses this with `codebase_search`, a powerful tool that performs hybrid semantic and keyword retrieval fused by reciprocal rank fusion. Instead of relying on simple text matching, Atlas indexes code by AST declarations using `tree-sitter`, providing a deeper understanding of the code's structure and intent. For an Echo developer, this means you can ask a plain-language question like "how are requests authenticated in this Echo service?" and Atlas will return ranked snippets from files such as `internal/auth/middleware.go` or `pkg/security/jwt.go`, even if those files don't explicitly contain the exact keywords. Atlas can build this code index with local Ollama embeddings, keeping your sensitive Echo code off third-party servers and ensuring privacy. ## How to understand Echo project structure and dependencies quickly? Understanding the overall structure of an Echo project and its dependencies is crucial, and Atlas helps you achieve this in under 5 minutes using `glob` and by analyzing `go mod`. This provides a high-level overview of the package layout and external libraries, such as `github.com/labstack/echo/v4`. After identifying key areas with `codebase_search`, gaining a sense of the project's architecture is the next step. Atlas's `glob` tool allows you to quickly map the top-level directories, revealing the package layout and naming conventions common in Echo applications, such as `cmd/`, `internal/`, `pkg/`, and `web/`. This helps you infer where `echo.Group` definitions might live or where custom binders are implemented. Furthermore, Atlas reads your `go.mod` file, which is the standard package manager for Go, to understand the project's dependencies. By examining `go.mod`, Atlas can identify that the project `requires github.com/labstack/echo/v4`, confirming its framework. This insight into the dependency graph helps you anticipate the types of middleware, handlers, and utilities you'll encounter, forming a foundational mental model without needing to open a single source file manually. ## How does Atlas help explore specific Echo handlers and middleware? To dive into specific Echo handlers and middleware, Atlas provides `read` for targeted file review and `lsp` for following definitions, allowing you to trace logic like `echo.NewHTTPError` usage. For broader sweeps, the `explore` subagent can investigate multiple files in a read-only mode, ensuring safety in 2026. Once you have a high-level understanding, you'll want to examine specific Echo components. Atlas's `read` tool allows you to pull only the two or three files that `codebase_search` ranked highest, or those identified by `glob` as central, such as `cmd/server/main.go` or `internal/handlers/user.go`. Within these files, the `lsp` tool's `goToDefinition` operation becomes invaluable for Echo developers. You can follow imports to understand custom `echo.Context` extensions, trace the implementation of a custom `Validator`, or see where `echo.NewHTTPError` is returned. For wider investigations, such as finding all instances of a specific middleware or custom binder across the codebase, you can delegate heavy fan-out to the `explore` subagent through the `task` tool. This subagent is permissioned read-only with a deny-by-default rule set, allowing it to safely `grep`, `glob`, `read`, `bash`, `webfetch`, and `websearch` without making any changes to your Echo project. ## How does Atlas ensure safety and review when learning an Echo codebase? Atlas ensures safety and provides comprehensive review mechanisms when interacting with an unfamiliar Echo codebase, preventing unintended changes in 2026. Every Atlas tool call is permission-gated, and all proposed edits are presented as a unified diff for your explicit approval before writing to disk. Safety is paramount when exploring an unfamiliar Echo codebase. Atlas is designed with multiple layers of protection. Every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs, giving you granular control. For instance, the `explore` subagent, used for wide sweeps, operates with a deny-by-default permission set, ensuring it can only read and search, never modify. When Atlas drafts a plan, it does so in a read-only plan agent and asks for your approval before switching to a build agent that could propose changes. If Atlas suggests adding a custom `Validator` or covering handlers with `go test` using `httptest`, it will first present a unified diff for every file edit. This diff, which can include changes to `internal/handlers/user_test.go` or `pkg/validation/validator.go`, must be approved by you. Atlas also snapshots file changes as `git` patches, so edits can be easily diffed and rolled back, providing a secure environment for learning and experimentation within your Echo project. ## How to record and track learning about an Echo codebase with Atlas? Recording what you learn and tracking open questions about an unfamiliar Echo codebase is essential for building a robust mental model, and Atlas facilitates this with the `todowrite` tool. This ensures that your insights and remaining queries persist across multiple Atlas sessions in 2026. As you navigate an unfamiliar Echo codebase, you'll uncover critical information, identify areas for deeper investigation, and formulate new questions. The `todowrite` tool in Atlas is specifically designed to help you record these findings. Instead of relying on external notes or trying to remember every detail, you can use `todowrite` to create a persistent list of open questions, observations about `echo.Group` routing, or specific details about custom `HTTPErrorHandler` implementations. For example, after exploring authentication, you might `atlas todowrite "Investigate the custom JWT middleware in internal/auth/jwt.go and its interaction with echo.Context."`. This ensures that your learning journey is documented directly within your Atlas session, allowing you to pick up exactly where you left off and maintain a clear understanding of your progress in building a mental model of the Echo application. ## Steps 1. Run `atlas codebase_search "how are requests authenticated in this Echo service?"` to semantically find relevant Echo authentication logic. 2. Execute `atlas glob "*/"` to examine the top-level directory structure and infer Echo package layout, such as `internal/handlers` or `pkg/middleware`. 3. Use `atlas read "internal/auth/middleware.go" "cmd/server/main.go"` to review core Echo files identified by semantic search and glob, focusing on `echo.Group` and `echo.Context` usage. 4. Apply `atlas lsp goToDefinition "echo.NewHTTPError"` to navigate to the definition of a key Echo error handling function and understand its usage across the codebase. 5. Delegate a read-only sweep with `atlas task explore "grep for all custom binders or validators in Echo handlers"` to find specific Echo idioms like custom binders or `echo.Validator` implementations. 6. Record open questions and findings about Echo's error handling using `atlas todowrite "Investigate the custom HTTPErrorHandler implementation in internal/app/error_handler.go and its interaction with echo.NewHTTPError."`. ## FAQ ### How does Atlas understand my Echo `go.mod` dependencies? Atlas reads your `go.mod` file, including the `require github.com/labstack/echo/v4` directive, to understand the project's dependency graph and context. This helps Atlas identify the Echo framework and its version. ### Can Atlas help me find all `echo.Group` routes in a new project? Yes, Atlas's `codebase_search` can semantically query for `echo.Group` definitions and usage patterns across your repository, providing ranked snippets from files like `cmd/server/main.go` or `internal/routes/api.go`. ### How does Atlas ensure it doesn't accidentally change my Echo code? Atlas uses a read-only plan agent, permission-gated tool calls, and presents a unified diff for approval before any changes are written to your Echo files. The `explore` subagent is also strictly read-only. ### What Atlas tool helps me see the overall directory structure of an Echo app? The `glob` tool allows you to quickly map the top-level directories and infer the package layout and naming conventions common in Echo projects, such as `internal/handlers` or `pkg/middleware`. ### Can Atlas help me understand how `httptest` is used with `go test` in an Echo project? Yes, you can use `codebase_search` to find examples of `httptest` usage within your `go test` files, or `read` specific test files like `internal/handlers/user_test.go` to see the patterns for testing Echo handlers. ### How does Atlas handle custom `HTTPErrorHandler` implementations in Echo? Atlas can read your custom `HTTPErrorHandler` definitions and trace how `echo.NewHTTPError` is used throughout your handlers, helping you understand the application's error flow and custom error responses. ### Does Atlas support `gofumpt` for Echo code formatting? Yes, Atlas can run `gofumpt` over touched packages in your Echo project and presents the diff for your review and approval before applying any formatting changes, ensuring code consistency. --- Canonical HTML: https://runatlas.sh/resources/stacks/onboard-to-an-unfamiliar-codebase-in-echo Source of truth: aeo_pages row `/resources/stacks/onboard-to-an-unfamiliar-codebase-in-echo` (segment: Stacks) (this file is generated from it, never hand-edited). Licence: Atlas is proprietary with a free core. It is not open source and there is no public source repository.