Build by chat on your phone

Build by chat lets you describe an app or a change in Jennefer Mobile, and one agent builds it in one of your cloud sandboxes. It uses a model kept in your account, so it works while your computer is off.

What you need#

• Jennefer Mobile with Cloud sandboxes open for your account.
• A Cloud plan. The sandbox uses your Cloud hours. See Plans and account.
• An existing sandbox. Sandboxes are created in Jennefer Cloud on your computer, not on the phone.
• A model kept in your account. On your computer, open Hub > Models > Your endpoint and turn on Use from your phone without this computer for a saved model. This needs a paid plan (Code Pro, Studio Pro, Workshop Pro, Hangar Pro, All Apps Pro or Team) and an endpoint address approved for your account. See Your endpoint.

Your computer can be off. Models on your computer cannot be used for builds.

Start a build#

1. 1

   Open the sandbox

   In Mobile, open Cloud sandboxes and choose Build by chat on a sandbox. On a paused sandbox it is under Start. It is hidden when you have no Cloud hours left.

2. 2

   Check the model

   The chip under the title shows the model. Tap it to pick another model in your account or an effort.

3. 3

   Describe it

   Write what to build or change in Describe the app, attach a screenshot or a spec if you like, and choose Build. A paused sandbox starts first, which checks your plan and Cloud hours.

Without a model in your account, the screen shows Add a model to your account and you cannot send.

While it builds#

• The answer shows Working and the agent's latest steps live: its thoughts, the files and commands it works on, and their results. A green dot marks a result that worked, a pink dot one that failed.
• The agent reads the project first, keeps to its stack, and can create, read, edit and search files and run commands in the sandbox. It starts the app's dev server and leaves it running.
• It is one agent, not the agent team. Commands and file changes run without approval cards, as in Cloud: the sandbox is isolated and disposable.
• When it ends, the answer shows Done, Stopped or Stopped with an error, and the agent's summary: what it built or changed, how to open it, and what is not done. A model error shows as Your endpoint answered: with the provider's message.
• Under each answer: Copy, Steps (N), and the model, effort, tokens, estimated cost and time. Try again sends the last request again after an error or a stop.
• Steps (N) lists the steps this phone saw while the screen was open. Steps are not saved on the phone.

Questions#

When the agent needs a decision from you, a Question card shows in the chat. Tap an option, or type and choose Send answer. A question that asks for a secret cannot be answered on the phone.

The build also shows in Runs as Phone build, with the usual push notifications.

Stop a build#

While the agent works, choose Stop under the chat or the button next to the message box. You can also stop it in Runs. The answer then shows Stopped. Files the agent already changed stay changed.

Open the preview#

When a build is Done, choose Open preview. It opens the app running in the sandbox in your phone's browser. If the sandbox has several ports, pick one under Open which port?. Nothing to open yet means no app is listening: ask the agent to start the dev server.

Build chats#

• Each sandbox has its own build chats. Chats shows Builds in the sandbox, with New build chat and the chats On this phone.
• New chat starts a new one with the same model.
• Edit or a long press gives Rename and Delete. Deleting removes the chat's messages and photos from this phone. The sandbox and its files stay.
• Each request carries the recent requests and summaries of its chat, so you can ask for changes one at a time.
• Build chats are stored only on this phone. The files stay in the sandbox, so you can keep working on them in Jennefer Cloud on your computer.

Model and effort#

Tap the model chip to open Model for this build chat. It lists the models In your account. A row that cannot be used says Needs a Pro plan or Address not approved.

Under Effort, choose Default, Low, Medium, High, Extra high or Max. Higher effort thinks longer before each step and uses more tokens. The choice is kept for the chat. See Model choice.

Photos and files#

Tap + and choose Photos or PDF or text file.

• Up to 4 photos per request, up to 10 MB each, such as a screenshot or a sketch of what to build. Only the agent's first step sees them. Use a model that can read images.
• Up to 3 PDF or text files per request, such as a spec. Their text goes in front of your request.
• PDFs can be up to 20 MB and 100 pages. They are read on Jennefer's servers to get their text, then dropped. Text files can be up to 2 MB and are read on the phone.

Costs#

Each answer shows its tokens and an estimated cost, and the header shows the chat's total. The cost is estimated from list prices when Jennefer knows the model's price. Your provider's bill is the real cost.

Limits#

• One agent run per account at a time. If an agent is running in the IDE, the CLI, Cloud or Workshop, the build says Another agent is running on your account. Stop it first, then send again. Hangar flights do not count.
• A build has at most 30 steps. Build a bigger app over several requests.
• Sandboxes are not created from the phone. If the sandbox was deleted, the build says This sandbox is gone. Create one in Jennefer Cloud on your computer.
• Without Cloud hours left, the build says Your Cloud hours for this period are used up.
• Jennefer's servers keep a build's request, steps and summary in memory for up to 24 hours, for your last 10 builds. If the server restarts during a build, the answer says The server lost this build. Try again.

FAQ#