# Plan a Multi-File Change Before Editing in Astro with Atlas in 2026

> Atlas enables Astro developers to plan and review multi-file changes, integrating with `pnpm`, `vitest`, and `prettier (prettier-plugin-astro)` for a safe, pre-edit workflow.

Atlas empowers Astro developers in 2026 to design multi-file changes and secure review approval before any code modification, leveraging real Astro tools like `pnpm` for package management, `vitest` for testing, and `prettier (prettier-plugin-astro)` for consistent formatting.

## Key takeaways

- Atlas's plan agent prevents accidental edits to your Astro codebase by restricting writes to a plan markdown file.
- Research your Astro project with `codebase_search`, `grep`, `read`, and `lsp` in plan mode, leveraging AST declarations.
- Get multi-file Astro changes reviewed and approved before a single line of code is written, using the `plan_exit` tool.
- Atlas integrates deeply with Astro's toolchain, understanding `astro.config.mjs`, `src/content.config.ts`, `pnpm`, `vitest`, and `prettier (prettier-plugin-astro)`.
- Approve every file edit with a unified diff before Atlas writes it, ensuring full control over your Astro project modifications.
- Atlas can use local Ollama embeddings, keeping your Astro code private and off third-party servers.

## How Atlas Plans Multi-File Astro Changes Safely

Atlas's dedicated plan agent ensures that Astro developers in 2026 can design complex, multi-file changes without risk of accidental modification. This agent operates with a strict permission set, allowing writes only to a plan markdown file, typically located under `.atlas/plans/*.md`, preventing any unintended edits to your `src/pages` or `src/content` directories.

When you initiate Atlas in plan mode, it activates a specialized plan agent whose primary function is to facilitate design and research without altering your codebase. This agent is configured with a highly restrictive permission set: it denies all edit tools for every path except a designated plan markdown file. This means you can freely explore your Astro project, using tools like `codebase_search`, `grep`, `read`, and `lsp`, without any possibility of accidentally modifying `astro.config.mjs`, `src/components`, or any other project file. The plan agent's read-only nature for your core project files is a fundamental safety mechanism, ensuring that your design phase remains entirely separate from implementation. This allows you to draft a comprehensive plan for a multi-file change, detailing modifications across `src/pages`, `src/layouts`, and `src/content` collections, all within a secure, non-destructive environment. The plan itself is written into a markdown file, which is the single location the plan agent is permitted to write to, providing a clear, reviewable artifact of your proposed changes.

## Researching Astro Codebases with Atlas's Plan Agent

When planning a multi-file change in Astro, Atlas's plan agent provides powerful research tools to understand your codebase in 2026. You can use `codebase_search` for semantic queries, `grep` for keyword matching across `src/components` or `src/layouts`, and `read` to inspect specific files like `astro.config.mjs`.

Atlas's plan agent equips Astro developers with a suite of robust research tools to thoroughly understand the codebase before proposing any changes. The `codebase_search` tool allows you to perform hybrid semantic and keyword retrieval, fused by reciprocal rank fusion, to locate relevant code sections across your Astro project. For instance, you might search for all Astro components that utilize a specific client directive or a particular data fetching pattern. Atlas indexes your code by AST declarations using tree-sitter, providing a more precise understanding than blind line windows. You can also use `grep` for traditional keyword searches across your `src` directory, or `read` to inspect the contents of specific files such as `src/pages/index.astro` or `src/content/blog/first-post.md`. The `lsp` tool provides language server protocol capabilities, offering insights into type definitions and references within your Astro components and TypeScript files. Crucially, Atlas can build its code index with local Ollama embeddings, ensuring that your Astro codebase remains off third-party servers, maintaining privacy and security for your proprietary code. This comprehensive research capability ensures that your multi-file change plan is well-informed and grounded in the current state of your Astro project.

## Reviewing and Approving Astro Changes Before Implementation

Atlas ensures a robust review process for Astro changes, allowing you to get approval on a detailed plan before a single line of code is modified. The `plan_exit` tool, when called, presents a clear prompt asking if the plan is complete, offering a critical 2-step handoff to the build agent.

The core benefit of planning multi-file changes with Atlas is the ability to secure review and approval before any actual code modification begins. Once you have thoroughly researched your Astro project and documented your proposed changes in the plan markdown file, you invoke the `plan_exit` tool. This tool initiates a crucial interaction, asking, 'Plan at <path> is complete. Would you like to switch to the build agent and start implementing?' Answering 'Yes' signals your readiness to proceed, transitioning control to the build agent, which then has the necessary permissions to begin implementing the changes outlined in your plan. Answering 'No' raises a `Question.RejectedError`, allowing you to continue refining your plan within the safe, read-only plan agent. This explicit handoff mechanism ensures that no implementation work begins until the plan is fully reviewed and approved. Furthermore, when the build agent eventually makes edits, Atlas computes a unified diff for every file modification and surfaces it for your approval before writing, and it snapshots file changes as git patches, allowing edits to be easily diffed and rolled back. This multi-layered approval process provides unparalleled safety and control over your Astro codebase.

## Integrating Astro Tooling for Pre-Edit Validation

Atlas integrates directly with your Astro project's established toolchain, ensuring that any proposed changes in 2026 align with your existing standards. This includes understanding `astro.config.mjs` for integrations, recognizing `src/content.config.ts` schemas, and preparing for `prettier (prettier-plugin-astro)` formatting.

Atlas is designed to be deeply aware of the Astro ecosystem, making it an invaluable partner for planning and implementing changes. It reads your `astro.config.mjs` to understand your project's integrations and configurations, ensuring that any proposed modifications are compatible with your existing setup. Atlas also comprehends your `src/pages` routes, allowing it to reason about page structures and navigation. For content-rich Astro sites, Atlas can read your content collection schemas defined in `src/content.config.ts`, enabling it to assist with tasks like adding a Zod schema to a content collection. When such schema modifications are proposed, Atlas can even run `astro check` behind a permission prompt, validating the changes against your project's type system before they are committed. This deep integration extends to your development workflow: Atlas is aware of `pnpm` as your package manager, `vitest` as your test runner, and `prettier (prettier-plugin-astro)` as your formatter. This means that when you transition to implementation, Atlas can facilitate running tests with `pnpm run test` (or `vitest`) and ensuring code consistency with `pnpm prettier --write .` (or `prettier --write .`), all within its terminal-native interface. This contextual awareness ensures that Atlas's assistance is always relevant and aligned with your Astro project's specific needs.

## Steps

1. Start Atlas in plan mode to begin designing your multi-file Astro change: `atlas agent plan`
2. Research your Astro codebase using `codebase_search` to find relevant components, e.g., `atlas codebase_search "Astro components using client:load"`
3. Inspect specific Astro files or configurations with `read`, such as `atlas read src/pages/blog/[slug].astro` or `atlas read astro.config.mjs`.
4. Document your detailed multi-file change plan in the designated markdown file, e.g., `atlas write .atlas/plans/new-astro-feature.md`.
5. Call `plan_exit` to propose your plan for review and, upon approval, switch to the build agent: `atlas plan_exit`.
6. Once in the build agent, implement the changes, leveraging Atlas's tools for code modification.
7. Run your Astro project's tests with `pnpm run test` (or `vitest`) to validate changes.
8. Format your modified Astro files using `pnpm prettier --write .` (or `prettier --write .`) to maintain code style.
9. Review the unified diffs for each file edit and approve them before Atlas writes the changes.
10. Stage and commit your changes with Atlas: `atlas commit`.

## FAQ

### How does Atlas prevent accidental edits in my Astro project?

Atlas's plan agent operates with a strict permission set, allowing writes only to a designated plan markdown file, typically under `.atlas/plans/*.md`, preventing any modifications to your `src/pages` or `src/components` until you explicitly switch to the build agent.

### Can Atlas understand my Astro content collections and config?

Yes, Atlas reads your `src/content.config.ts` to understand content collection schemas and your `astro.config.mjs` for integrations. It can even assist in adding Zod schemas and running `astro check` behind a permission prompt.

### What Astro tools does Atlas integrate with for development?

Atlas integrates with your core Astro toolchain, including `pnpm` for package management, `vitest` for running tests, and `prettier (prettier-plugin-astro)` for consistent code formatting across your project.

### How do I get a multi-file Astro change reviewed before I start coding?

Use Atlas's plan agent to research and write your detailed plan into a markdown file. Once complete, call `plan_exit` to propose the plan for review and, upon approval, switch to the build agent for implementation.

### Does Atlas keep my Astro code private when indexing?

Yes, Atlas can build its code index using local Ollama embeddings, ensuring your Astro codebase remains off third-party servers and your proprietary code stays private.

### Can Atlas help me refactor Astro components across many files?

While in plan mode, Atlas helps you design the refactor by researching your codebase with `codebase_search` and `lsp`. Once the plan is approved and you switch to the build agent, Atlas can then assist in implementing those multi-file component changes, always with diff approval.

### How does Atlas ensure my Astro code adheres to formatting standards?

Atlas recognizes `prettier (prettier-plugin-astro)` as your formatter. After making changes, you can instruct Atlas to run `pnpm prettier --write .` (or `prettier --write .`) to automatically format your Astro files according to your project's configuration.

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