How does Atlas handle Lua stack traces from different builds?

Atlas validates each `file:line` offset in a Lua stack trace against the current file content. If an offset is out of range, Atlas reports it, indicating the trace is from an older build and prompting you to re-read the file from the top for accurate debugging.

Can Atlas find callers of a Lua function that caused an error?

Yes, after identifying a failing Lua function, Atlas uses its `lsp` tool with the `findReferences` operation to list all callers that can reach that function, helping trace the origin of bad input.

Does Atlas support Lua's package manager `luarocks`?

Yes, Atlas is designed to work within your Lua development environment, reading modules and the rocks resolved by `luarocks` to build its code index and understand dependencies.

How does Atlas ensure I review changes before they are applied to my Lua code?

Atlas drafts a plan in a read-only agent and asks for approval before executing changes. For every `edit` operation on Lua files, it computes and surfaces a unified diff for your review and approval before writing.

Can Atlas help me write `busted` tests for Lua bugs?

Absolutely. Atlas can be instructed to add `busted describe` and `it` blocks under your `spec/` directory to create new regression tests, and then run `busted` to validate the fix.

Is my Lua code safe with Atlas, or does it go to third-party servers?

Atlas prioritizes privacy. It can build its code index with local Ollama embeddings, keeping your Lua code and sensitive project details entirely off third-party servers.

How does Atlas handle Lua code formatting?

Atlas integrates with `stylua`, the Lua formatter. After making changes, you can have Atlas run `stylua` over the touched modules to ensure your code adheres to project-specific formatting standards.

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

In 2026, Lua developers can trace a runtime bug from a production stack trace to the responsible line and a fix without attaching a debugger by using Atlas, which integrates directly with your `luarocks` modules and `busted` tests.

How Atlas reads and validates Lua stack traces from production

Atlas in 2026 efficiently reads Lua production stack traces, which are lists of `file:line` pairs, by consuming each frame at its reported offset. This process includes a crucial validation step: Atlas checks if the reported offset is within the current file's bounds, preventing misdiagnosis from outdated builds.

When a Lua application encounters a runtime error in production, it often generates a stack trace detailing the sequence of function calls leading to the error. Atlas is designed to consume these raw stack traces directly. A typical Lua stack trace provides `file:line` pairs, such as `main.lua:42` or `lib/my_module.lua:123`. Atlas uses its `read` tool to process each frame, opening the specified Lua file and navigating to the reported line number. This direct approach means you paste the stack trace into Atlas, and it immediately begins analyzing the context. A critical safety feature of Atlas is its offset validation. If a stack trace originates from an older build of your Lua codebase, the line numbers might no longer correspond to the current file content. Atlas detects this by reporting "Offset <n> is out of range for this file," prompting you to re-read the file from the top before trusting any line number. This prevents Atlas from pointing you to incorrect code, ensuring that the debugging process starts with accurate information, whether your Lua code is part of a Neovim plugin, an OpenResty handler, or an embedded game script.

How to find the root cause of a Lua bug with Atlas's search tools

After reading a Lua stack trace, Atlas helps pinpoint the root cause of a bug by leveraging its `grep` and `lsp` tools. In 2026, developers can search for the error message string to find its construction point, which is often more informative than the top frame of the trace.

Once Atlas has processed the initial Lua stack trace, the next step is to identify the precise location and conditions causing the error. The top frame of a stack trace often indicates where an error was *thrown*, but not necessarily where the *bad input* originated. Atlas addresses this by allowing you to `grep` for the specific error message string. For instance, if your Lua application throws an error like "attempt to index a nil value (field 'name')", you can instruct Atlas to `grep` for "attempt to index a nil value". This often leads to the code responsible for constructing the error message, providing a more direct path to the underlying issue. Furthermore, Atlas integrates with the Language Server Protocol (LSP) through its `lsp` tool. If the `grep` operation points to a function that is failing, you can use `lsp findReferences` on that function. This powerful operation reveals all callers that can reach the failing function, allowing you to trace back the flow of data and identify where the "bad input" might have been introduced. This is particularly useful in complex Lua projects using `luarocks` for dependency management, where modules might be deeply nested. Atlas's hybrid semantic and keyword retrieval, fused by reciprocal rank fusion, ensures comprehensive search results across your Lua codebase, including module returns and metatables.

How Atlas helps fix Lua bugs and add regression tests

Atlas streamlines the process of fixing Lua bugs and ensuring they do not recur silently by using its `edit` tool and integrating with `busted`. After identifying the responsible line in 2026, Atlas can apply the fix and then prompt to run `busted` tests to validate the change.

After successfully tracing a runtime bug in your Lua codebase to its responsible line using Atlas's `read`, `grep`, and `lsp` tools, the next logical step is to implement a fix and prevent future regressions. Atlas facilitates this with its `edit` tool. You can instruct Atlas to modify specific lines or blocks of Lua code, for example, to replace a global with a local upvalue or add necessary nil checks. Before committing any changes, Atlas computes a unified diff for every file edit and surfaces it for your approval, ensuring transparency and control over the modifications. Crucially, Atlas integrates with the Lua testing ecosystem. After applying a fix, you can ask Atlas to add `busted describe` and `it` blocks under your `spec/` directory, creating a targeted regression test. Atlas can then run `busted` behind a permission prompt, validating that your fix resolves the issue and that no new issues have been introduced. This ensures that the bug cannot recur silently. Finally, to maintain code quality and consistency across your project, Atlas can run `stylua` over the touched modules, automatically formatting the Lua code according to your project's standards. Atlas reads git branches, status, and diffs, and can stage and create commits on your behalf, making the entire fix and test cycle efficient.

How Atlas ensures safety and review for Lua code changes

Atlas provides robust safety and review mechanisms for all Lua code changes, ensuring developers maintain full control over their projects in 2026. Every Atlas tool call is permission-gated, and changes are presented as unified diffs for approval, preventing unintended modifications to critical Lua modules.

When working with an AI coding agent like Atlas on your Lua codebase, safety and control are paramount. Atlas is built with several layers of protection to ensure that all modifications are intentional and reviewed. Firstly, every Atlas tool call, including `read`, `grep`, `lsp`, and `edit`, is permission-gated against allow, ask, and deny rules. This means you explicitly control what actions Atlas can take on your Lua files, `rockspec` definitions, or `spec/` test files. Before any code modification, Atlas drafts a plan in a read-only plan agent and asks for your approval before switching to a build agent to execute the changes. This "plan and ask" approach provides a crucial review step. Furthermore, for every file edit, Atlas computes a unified diff and surfaces it for your approval before writing to disk. This allows you to meticulously review exactly what changes Atlas proposes to your Lua modules, such as `my_module.lua`, or configuration files. Atlas also snapshots file changes as git patches, so edits can be diffed and rolled back if necessary. This comprehensive review process, combined with Atlas's ability to build its code index with local Ollama embeddings, keeping your sensitive Lua code off third-party servers, ensures that your development workflow remains secure and under your complete control, whether you're debugging a Neovim plugin or an OpenResty handler.

Step by step

01Paste the production Lua stack trace into Atlas and instruct it to `read` each frame's `file:line` at the reported offset.
02If Atlas reports "Offset <n> is out of range for this file" for a Lua module, re-read the file from the top before trusting any line number from that trace.
03Use Atlas's `grep` tool to search for the specific error message string within your Lua codebase to find where it is constructed, which is often more informative than the top stack frame.
04If the `grep` result points to a failing Lua function, use Atlas's `lsp findReferences` operation on that function to identify all callers that could reach it with the bad input.
05Instruct Atlas to `edit` the responsible Lua file, such as `src/my_library.lua`, to apply the necessary fix, reviewing the unified diff for approval.
06Ask Atlas to add a new `busted describe` and `it` block under your `spec/` directory to create a regression test for the identified Lua bug.
07Allow Atlas to run `busted` behind a permission prompt to validate the fix and ensure the regression test passes.
08Have Atlas run `stylua` over the touched Lua modules to ensure code formatting consistency before committing.

Frequently asked questions

How does Atlas handle Lua stack traces from different builds?: Atlas validates each `file:line` offset in a Lua stack trace against the current file content. If an offset is out of range, Atlas reports it, indicating the trace is from an older build and prompting you to re-read the file from the top for accurate debugging.
Can Atlas find callers of a Lua function that caused an error?: Yes, after identifying a failing Lua function, Atlas uses its `lsp` tool with the `findReferences` operation to list all callers that can reach that function, helping trace the origin of bad input.
Does Atlas support Lua's package manager `luarocks`?: Yes, Atlas is designed to work within your Lua development environment, reading modules and the rocks resolved by `luarocks` to build its code index and understand dependencies.
How does Atlas ensure I review changes before they are applied to my Lua code?: Atlas drafts a plan in a read-only agent and asks for approval before executing changes. For every `edit` operation on Lua files, it computes and surfaces a unified diff for your review and approval before writing.
Can Atlas help me write `busted` tests for Lua bugs?: Absolutely. Atlas can be instructed to add `busted describe` and `it` blocks under your `spec/` directory to create new regression tests, and then run `busted` to validate the fix.
Is my Lua code safe with Atlas, or does it go to third-party servers?: Atlas prioritizes privacy. It can build its code index with local Ollama embeddings, keeping your Lua code and sensitive project details entirely off third-party servers.
How does Atlas handle Lua code formatting?: Atlas integrates with `stylua`, the Lua formatter. After making changes, you can have Atlas run `stylua` over the touched modules to ensure your code adheres to project-specific formatting standards.

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