Atlas plans a multi-file TypeScript change inside a plan agent whose description is literally Plan mode. Disallows all edit tools. The agent researches your tsconfig.json, your path aliases, and your src directory with codebase_search, grep, read, and the lsp tool, writes the design into a plan markdown file, then calls plan_exit to ask whether to switch to the build agent. Nothing in your TypeScript sources is touched until you answer Yes, and only after that do pnpm, vitest, and prettier come into play.
How does Atlas plan a multi-file TypeScript refactor before editing anything?
Atlas plans a multi-file TypeScript refactor in a plan agent whose description is literally Plan mode. Disallows all edit tools. The plan agent denies edit for every path except .atlas/plans/*.md, so a TypeScript developer can map tsconfig.json path aliases and every affected module in 2026 without risking a write.
The plan agent in Atlas exists because a TypeScript refactor that crosses ten files is a design problem before it is an editing problem. Renaming an exported interface in src/domain/invoice.ts ripples through every import that resolves through a tsconfig.json path alias, through the .d.ts surface you publish, and through every vitest spec that constructs the old shape. Atlas drafts a plan in a read-only plan agent and asks before switching to a build agent, which means the ripple gets enumerated on paper first. Research runs through codebase_search, which searches code with hybrid semantic and keyword retrieval fused by reciprocal rank fusion, so asking where invoice totals are computed surfaces the right TypeScript modules even when the word total never appears in them.
Which Atlas tools stay allowed in TypeScript plan mode?
Atlas keeps codebase_search, grep, read, the lsp tool, and question available in plan mode, plus plan_exit. Edit is denied for every path and allowed only under .atlas/plans/*.md, so a TypeScript developer reading src/services/billing.ts or a generated .d.ts file in 2026 can never accidentally write to it.
Each allowed tool does a different job in a TypeScript repository. codebase_search answers meaning questions against the semantic index, and Atlas indexes code by AST declarations using tree-sitter, not blind line windows, so a hit lands on the exported function or interface rather than a random 40-line slice. grep runs a real regex through ripgrep when you need the literal string, for example every call site of createStripeClient. read opens the file. The lsp tool gives you the TypeScript symbol graph, which is what tells you that a type exported from src/types/index.ts is consumed in nineteen places. The question tool is how the plan agent asks you something instead of guessing.
Where does Atlas write the TypeScript plan file?
Atlas writes the plan into a markdown file under .atlas/plans, the one path the plan agent is permitted to write. For a TypeScript change touching tsconfig.json path aliases and a dozen modules, that single 2026 markdown file is the artifact your teammate reviews before the build agent runs.
The plan markdown path is not a convention, it is the permission boundary. The plan agent's permission set denies edit for every path and allows it only under .atlas/plans/*.md, so writing the plan is the sole write the agent can perform. A good TypeScript plan names the files it will change, the exported types it will move, the vitest specs that will need updating, and whether prettier will reformat the touched files. Because Atlas computes a unified diff for every file edit and surfaces it for approval before writing, even the plan file itself shows up as a reviewable diff rather than a silent write.
How do I hand off from the Atlas plan agent to the build agent?
Call plan_exit. Atlas asks: Plan at the given path is complete. Would you like to switch to the build agent and start implementing? Answering Yes hands the TypeScript plan to the build agent. Answering No raises Question.RejectedError and keeps you refining, which in 2026 is the common case on a first draft.
The plan_exit tool is the gate between design and implementation in Atlas. Answer No and the plan agent stays where it is, still denied edit outside .atlas/plans/*.md, and you keep iterating with codebase_search and the lsp tool until the TypeScript plan actually accounts for the strict-mode errors the change will surface. Answer Yes and the build agent picks up the plan and starts editing your src files, where every Atlas tool call is permission-gated against allow, ask, and deny rules before it runs. The handoff is explicit on purpose. A build agent that started implementing on its own would defeat the point of planning.
What do I run after the build agent applies the TypeScript plan?
After the Atlas build agent applies a multi-file TypeScript plan, run vitest to prove behavior held, run prettier over the touched files, and install any new dependency with pnpm. Atlas snapshots file changes as git patches, so a 2026 refactor that goes wrong can be diffed and rolled back.
The verification loop for TypeScript is short and concrete. vitest is the test runner, so the whole suite runs there, and specs that construct a moved interface fail loudly rather than silently compiling. prettier is the formatter, so the diff you review is a behavior diff and not a whitespace argument. pnpm is the package manager, so a plan that adds a dependency lists the exact pnpm add that the build agent will propose. Atlas reads git branches, status, and diffs, and can stage and create commits on your behalf, which means the finished refactor lands as one reviewable commit rather than a pile of unstaged changes across your src tree.
Step by step
- 01Start Atlas in your TypeScript project, the directory where tsconfig.json lives, and let it read your type definitions, path aliases, and strictness settings.
- 02Switch to the plan agent: its permissions deny edit for every path and allow edit only under .atlas/plans/*.md, so no src file can change while you design.
- 03Ask codebase_search a plain-language question about the behavior you are changing, then confirm the exact call sites with grep and open the top candidates with read.
- 04Use the lsp tool to walk the TypeScript symbol graph and enumerate every module that imports the interface or function you plan to move.
- 05Write the plan into the allowed markdown path under .atlas/plans, listing each file to touch, each vitest spec to update, and any dependency to add with pnpm.
- 06Call plan_exit and read the prompt: Plan at the given path is complete. Would you like to switch to the build agent and start implementing? Answer No to keep refining.
- 07Answer Yes to hand off to the build agent, then review the unified diff Atlas surfaces for each TypeScript file before it is written.
- 08Run vitest to confirm the suite is green, run prettier over the changed files, and let Atlas stage the result as a single commit.
Frequently asked questions
- how to plan a large typescript refactor with an ai agent
- Use the Atlas plan agent. Its permissions deny edit for every path except .atlas/plans/*.md, so it can research your tsconfig.json, path aliases, and src modules with codebase_search, grep, read, and the lsp tool, then write a plan file you review before any TypeScript source is edited.
- can atlas edit files while in plan mode
- No. The Atlas plan agent's description is literally Plan mode. Disallows all edit tools, and its permission set denies edit for every path except the plan markdown under .atlas/plans/*.md. The only write it can perform is the plan file itself.
- what is plan_exit in atlas
- plan_exit is the Atlas tool that ends plan mode. It asks whether the plan at the given path is complete and whether you want to switch to the build agent and start implementing. Yes hands off to the build agent, No raises Question.RejectedError and keeps you refining the plan.
- does atlas understand tsconfig path aliases when planning a change
- Atlas reads your tsconfig.json, type definitions, path aliases, and strictness settings when you run it in a TypeScript project. During planning it resolves the affected modules with codebase_search and the lsp tool, so aliased imports are enumerated rather than guessed.
- how do i review an ai code change before it is written to disk
- Atlas computes a unified diff for every file edit and surfaces it for approval before writing, and every tool call is permission-gated against allow, ask, and deny rules. In a TypeScript repo you see the exact diff for each src file before it lands.
- how do i verify a multi-file typescript change atlas made
- Run vitest for the test suite and prettier for formatting, and install any new dependency with pnpm. Atlas also snapshots file changes as git patches, so the whole multi-file change can be diffed and rolled back if the suite goes red.
- which atlas tools work in plan mode for typescript
- codebase_search, grep, read, the lsp tool, question, and plan_exit. All research tools stay allowed, while edit is denied for every path except .atlas/plans/*.md, which is why plan mode is safe to run against a large TypeScript monorepo.
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