Cursor shipped Builds for its Cloud Agents on 13 August. The pitch is a performance number — 3x faster time to first token, 10x faster boot in internal measurement — but the interesting part is what had to change to get it.
A cloud agent has always paid a tax before doing anything useful: clone the repository, install dependencies, wait. Builds moves that work out of the critical path by preparing ready-to-use copies of your development environment in the background, before you ask for one.
What a build is
A build is a prepared copy of your development environment — dependencies installed, ready to run. Cursor keeps them warm in the background so an agent starting a task attaches to one rather than constructing it.
The configuration split that makes this work is separate install and start commands: install is the expensive, cacheable environment preparation, start is the cheap per-session initialisation. Anything you can move from start into install is time you stop paying on every single run.
The resilience behaviour is the underrated feature
When something goes wrong with a build, agents continue using the last successful one.
That is a bigger deal than the speed number for anyone who has watched a dependency change break an agent pipeline. Without it, a broken lockfile or an upstream package removal stops your agents entirely; with it, they keep working from the last environment that built cleanly.
It also introduces a failure mode to be aware of: an agent can be working against a stale environment while you assume it is on the current one. If agent output starts disagreeing with what you see locally, check which build it attached to before you debug the code.
What the Builds tab gives you
There is a dedicated tab showing build status, logs, commit SHAs and agent run history.
Commit SHAs and run history together are what make an agent run reproducible. Knowing which environment a run used is the difference between "the agent got it wrong" and "the agent was working from a version of the repository that no longer exists", and those need completely different responses.
Free, and on by default for new environments
Builds are included with Cloud Agents at no additional cost and enabled automatically for new environments.
The pricing decision tells you what Cursor thinks this is. Startup latency is not a feature you sell — it is friction that stops people using cloud agents at all, and removing it is how you get the usage that a usage-priced product depends on.
For existing environments, it is worth checking whether builds are enabled rather than assuming. Automatic applies to new ones.