How does Atlas handle different React project structures (Vite, Next.js)?

Atlas builds its code index by AST declarations using Tree-sitter, allowing it to understand various React project structures, from Vite to Next.js, and correctly parse components, hooks, and bundler configurations within your `package.json`.

Can Atlas fix bugs in both class components and functional components with hooks?

Yes, Atlas understands both class components and functional components with hooks. It can even convert class components to hooks or add React Testing Library tests, demonstrating its deep understanding of React idioms and codebase structures.

What if my production stack trace is from an older build of my React app?

Atlas validates offsets against the current file. If `read` reports "Offset is out of range for this file", it indicates the trace is from an older build. Atlas will loudly fail and prompt you to re-read the file from the top before trusting any line number.

How does Atlas ensure I review changes before they are applied to my React codebase?

Atlas operates with explicit approval. It drafts a plan in a read-only agent and asks for your permission before switching to a build agent. For every file edit, it computes a unified diff and surfaces it for your approval before writing any changes to your React files.

Can Atlas help me write `Vitest` tests for my React components?

Yes, Atlas can assist in adding `Vitest with React Testing Library` tests. It understands the test runner and can draft new test files or modify existing ones, helping you cover new scenarios or add regression tests for fixed bugs in your React components.

Does Atlas integrate with `prettier` for code formatting in React projects?

While Atlas focuses on code understanding and modification, it respects your project's existing toolchain. After Atlas makes an `edit`, you can run `pnpm prettier --write .` to ensure all changes to your React components and files conform to your project's formatting standards.

Is my React code sent to third-party servers when using Atlas?

No, Atlas can build its code index with local Ollama embeddings, keeping your React code entirely off third-party servers. This ensures your proprietary codebase remains secure and private throughout the bug tracing and fixing process.

Trace a runtime bug from a stack trace in React with Atlas in 2026

In 2026, React developers can efficiently trace runtime bugs from production stack traces to a precise fix without attaching a debugger, using Atlas directly in their terminal. Atlas leverages its `read`, `grep`, and `lsp` tools to navigate your React codebase, from `package.json` to individual components and hooks, identifying the root cause and proposing a solution. This solution can then be validated with `Vitest with React Testing Library` and integrated into your project using `pnpm`.

How Atlas traces runtime bugs in React applications from a stack trace

Atlas streamlines tracing runtime bugs in React applications by consuming a production stack trace directly. In 2026, Atlas uses its `read` tool to examine each frame's file and offset, validating against the current codebase. If an offset is out of range, indicating an older build, Atlas re-reads the file from the top before proceeding, ensuring accurate line targeting.

Atlas begins the bug tracing process by taking a raw production stack trace, which is a list of `file:line` pairs. For each frame in the trace, Atlas employs its `read` tool to inspect the specified file at the reported offset. This is crucial for React applications, where a single error can propagate through multiple components or hooks. Atlas's AST-based indexing, powered by Tree-sitter, allows it to understand the structure of your React components, hooks, and utility files, whether they are `.jsx` or `.tsx`. If the `read` tool detects that an offset is out of range for the current file, it signals that the stack trace likely originated from an older build. In such cases, Atlas will loudly report the discrepancy and advise re-reading the file from the top to ensure that any subsequent analysis points to the correct lines in your current React codebase. Following this, Atlas can use `grep` to search for the error message string, often revealing where the error is constructed rather than just where it manifests. Finally, the `lsp` tool's `findReferences` operation can be used on the failing React function or hook to identify all its callers, helping to trace the flow of bad input through your application.

Concrete Atlas commands and React files for tracing production issues

Tracing a production bug in a React application with Atlas involves specific commands and file interactions. For example, after pasting a stack trace, Atlas might `read src/components/MyComponent.jsx:42` to inspect a failing line. It then uses `grep` to locate the error message within your `src` directory, often revealing the error's construction point, which is more informative than the top frame.

To effectively trace a bug in your React project, Atlas integrates directly with your existing development environment. After initializing Atlas in a project managed by `pnpm` and containing a `package.json` file, you can paste a production stack trace. Atlas will then execute commands like `atlas read src/components/UserProfile.jsx:75` to examine the exact line of code indicated in the trace. If the initial `read` suggests an outdated trace, you would use `atlas read src/components/UserProfile.jsx` to get the current file context. To find the origin of an error message, you might instruct Atlas to run `atlas grep "Cannot read properties of undefined" src/`, targeting common React error patterns within your source files. Once a problematic function or hook, such as `useDataFetcher`, is identified, `atlas lsp findReferences useDataFetcher` can be used to list all locations where this function is called, helping to pinpoint where invalid data might be passed. Atlas understands and navigates typical React file structures, including `src/components/`, `src/hooks/`, and `src/utils/`, ensuring that its operations are always relevant to your React codebase.

Reviewing and safely applying bug fixes in React with Atlas

Atlas prioritizes safety and developer control when applying fixes to React applications. Every Atlas tool call, including `edit` operations on your `.jsx` or `.tsx` files, is permission-gated, requiring your explicit approval. Before any changes are written, Atlas computes a unified diff, presenting it for your review, ensuring you have 100% oversight of proposed modifications.

When Atlas proposes a fix for a bug in your React application, it does so with a strong emphasis on safety and transparency. All Atlas tool calls, including those that modify your React components, hooks, or configuration files, are permission-gated. This means you have granular control, with options to `allow`, `ask`, or `deny` any action Atlas suggests. Before any `edit` operation is executed, Atlas drafts a comprehensive plan in a read-only plan agent, which you can review. Only after your approval does it switch to a build agent to implement the changes. Crucially, for every file edit, Atlas computes a unified diff, clearly showing the proposed changes to your `.jsx`, `.tsx`, or other project files. This diff is surfaced for your approval, giving you complete visibility and the opportunity to accept, modify, or reject the changes. Atlas also integrates with Git, allowing it to read branches, status, and diffs, and even stage and create commits on your behalf. It snapshots file changes as git patches, ensuring that any edits can be easily diffed, reviewed, and rolled back if necessary, providing a robust safety net for your React development workflow.

Adding regression tests for React bugs with Vitest and React Testing Library

After fixing a runtime bug in a React component, adding a regression test is crucial to prevent its silent recurrence. Atlas can assist in drafting new tests using `Vitest with React Testing Library`. For instance, it might suggest a test file like `src/components/MyComponent.test.jsx` that specifically triggers the fixed bug, ensuring the issue remains resolved for future builds in 2026.

A critical step in the bug-fixing workflow for React applications is to ensure the identified issue does not reappear. Atlas facilitates this by helping you add regression tests using `Vitest with React Testing Library`. Once Atlas has proposed and you have approved a fix for a React component or hook, you can instruct it to `edit` a new test file or modify an existing one. For example, if a bug was found in `src/components/ProductCard.jsx`, Atlas could help create `src/components/ProductCard.test.jsx` with a test case specifically designed to trigger the previously failing scenario. Atlas understands the conventions of `Vitest` and `React Testing Library`, allowing it to generate relevant test code that mounts components, simulates user interactions, and asserts expected outcomes. This proactive approach, integrated into your `pnpm` based workflow, ensures that the bug is not only fixed but also permanently guarded against, providing long-term stability for your React application. Running `pnpm test` will then validate both the fix and the new regression test, confirming the bug's resolution.

Step by step

01Initialize Atlas in your React project by running `atlas` in the root directory, allowing it to index your components, hooks, and `package.json`.
02Paste the production stack trace into Atlas. Atlas will automatically use `read` to inspect each `file:line` frame, for example, `atlas read src/components/UserProfile.jsx:75`.
03If Atlas reports "Offset <n> is out of range for this file", re-read the file from the top using `atlas read src/components/UserProfile.jsx` to align with your current build.
04Instruct Atlas to `grep` for the error message string from the trace within your React codebase, e.g., `atlas grep "Cannot read properties of undefined" src/`, to find where the error is constructed.
05Use `atlas lsp findReferences <failingReactFunctionName>` on the identified problematic React function or hook to see all its callers and trace the bad input.
06Approve Atlas's plan to `edit` the responsible React file (e.g., `src/utils/dataFetcher.js` or `src/hooks/useAuth.ts`) to implement the proposed fix, carefully reviewing the unified diff.
07Have Atlas `edit` a new regression test file (e.g., `src/components/UserProfile.test.jsx`) using `Vitest with React Testing Library` to prevent the bug from recurring.
08Run your tests with `pnpm test` (or `vitest`) to confirm the fix and the new regression test pass for your React application.
09Approve Atlas to stage and commit the changes, including the fix and the new `Vitest` test, ensuring your Git history is clean.

Frequently asked questions

How does Atlas handle different React project structures (Vite, Next.js)?: Atlas builds its code index by AST declarations using Tree-sitter, allowing it to understand various React project structures, from Vite to Next.js, and correctly parse components, hooks, and bundler configurations within your `package.json`.
Can Atlas fix bugs in both class components and functional components with hooks?: Yes, Atlas understands both class components and functional components with hooks. It can even convert class components to hooks or add React Testing Library tests, demonstrating its deep understanding of React idioms and codebase structures.
What if my production stack trace is from an older build of my React app?: Atlas validates offsets against the current file. If `read` reports "Offset <n> is out of range for this file", it indicates the trace is from an older build. Atlas will loudly fail and prompt you to re-read the file from the top before trusting any line number.
How does Atlas ensure I review changes before they are applied to my React codebase?: Atlas operates with explicit approval. It drafts a plan in a read-only agent and asks for your permission before switching to a build agent. For every file edit, it computes a unified diff and surfaces it for your approval before writing any changes to your React files.
Can Atlas help me write `Vitest` tests for my React components?: Yes, Atlas can assist in adding `Vitest with React Testing Library` tests. It understands the test runner and can draft new test files or modify existing ones, helping you cover new scenarios or add regression tests for fixed bugs in your React components.
Does Atlas integrate with `prettier` for code formatting in React projects?: While Atlas focuses on code understanding and modification, it respects your project's existing toolchain. After Atlas makes an `edit`, you can run `pnpm prettier --write .` to ensure all changes to your React components and files conform to your project's formatting standards.
Is my React code sent to third-party servers when using Atlas?: No, Atlas can build its code index with local Ollama embeddings, keeping your React code entirely off third-party servers. This ensures your proprietary codebase remains secure and private throughout the bug tracing and fixing process.

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