Build steps

While a run is in flight, a small panel appears under the builder's reply in the chat. It lists what the builder is doing, newest at the bottom. Only the last eight steps are shown; earlier ones scroll out of view but are kept on the run.

Each step has a kind, which decides its icon, and a title.

The kinds

Kind	Icon	Meaning
read	magnifying glass over a page	The builder opened a file to see what is in it.
edit	page with a pencil	A file was written, changed or deleted.
command	terminal	A shell command ran, or the sandbox did something.
install	package	A package was installed.
error	red warning triangle	Something went wrong. Worth reading.
done	sparkles	The run finished.
think	sparkles	Reserved for the builder's own reasoning.

Every step title you can see

There is no fixed sequence of phases. The list is generated from what the builder actually did, so no two runs look the same. This is the complete set of titles the product can produce.

Getting the sandbox ready

These appear at the start of the very first build on a project, and occasionally later if the development server needs restarting.

Title	When
Copying the app template…	First build. The starter Next.js app is being copied into your project.
Installing dependencies (first build only — this takes a minute)…	First build, local sandbox. npm install is running.
Creating a cloud sandbox…	First build, cloud sandbox.
Uploading the app template…	First build, cloud sandbox.
Installing dependencies in the sandbox (this takes a few minutes)…	First build, cloud sandbox.
Starting the dev server…	The development server is being started.
Restarting the dev server…	The server was not answering and is being replaced.

These are the slowest part of a first build and they only happen once per project. Later builds skip straight past them.

Working on your app

Title	Meaning
Read <path>	The builder opened that file.
Wrote <path>	The file was created, or its whole contents were replaced.
Edited <path>	A piece of text inside the file was replaced.
Deleted <path>	The file was removed.
Installed: <command>	A package install ran. The command is shown, cut at 80 characters.
Ran: <command>	Any other shell command.
Restarted the dev server	The builder restarted the server itself, usually after changing a config file.

Every Wrote, Edited and Deleted step also creates a version history entry. A Ran: step does not — see the limits of version history.

Things going wrong

Title	Meaning
<tool> failed	One tool call failed. The builder normally reads the error and tries something else, so a single one of these is not a problem.
Model call failed (attempt undefined) — retrying	The AI provider returned an error or a rate limit and the request is being retried. Up to two retries, with an increasing delay. The word "undefined" in place of the attempt number is a known display defect; the retry itself works.
Out of credits — stopping	Your balance reached zero partway through. See Credits.
Stopped: repeated actions without progress	The builder repeated itself and was stopped.
The run failed	The run threw an error and ended. The reason is in the chat.

Finishing

Title	Meaning
Finished	The builder called finish and wrote its summary.

Reading a step list usefully

Three patterns are worth recognising:

A long stretch of Read steps at the start. The builder is orienting itself in an app that already has a lot of files. Normal, and it gets more common as your project grows.

A <tool> failed immediately followed by a Read. The builder tried an edit that did not match, went back to look at the file properly, and is about to try again. This is the system working.

The same Edited <path> over and over. The builder is fighting with one file. If the loop detector does not catch it, cancel the run and describe the problem more concretely.

Where steps are kept

Steps are stored against the run permanently, not just streamed to your browser. The eight-step window in the chat is a display limit only. There is currently no screen in the product that shows the full step list of a past run — the chat shows the builder's summary message instead.

Next

• The sandbox — what those "Starting the dev server" steps are actually doing.
• When a build fails.