Thinkube Tandem

Build your first application change with Tandem

Write what you want in plain sentences, see how they were read, sign the promises, and get the change running in your app

Level: beginner
Time: 1 h
Risk: low
Updated: 2026-10-04

TandemSentencesPromisesReports

Overview

Basic idea

You say what you want in the words you would use with a person. Tandem turns the words into promises (what will be true when the work is done), proves each promise with a check written before the code, builds the change, deploys it and tells you, sentence by sentence, what happened.

Reading only shows; nothing is saved until you press Keep. Tandem shows how it understood each sentence, so a misreading costs one press.
Your words are the record. Once kept, your sentences are never edited by the machine; everything derived from them can be made again.
Signing freezes what runs. The run builds exactly the promises you signed.
The report answers your sentences. Each sentence gets one word, with the checks that proved it.
The decisions are yours. Only you can keep, sign and accept. Claude Code can write the sentences. Tandem gives it no tool for the rest.

What you’ll accomplish

You make a todo app from the web app template, write nine sentences about it, and build the first of the things Tandem groups them into, until it runs at the app’s address.

What to know before starting

Required

Thinkube IDE open, with the Tandem icon in the activity bar.

Optional

Thinkube Tandem: how a sentence becomes a promise, and how a run works.
The words on the page: every label and state word.

Supported hardware

GPU: not needed. Tandem’s model rounds call Claude, and the app is built and deployed by the platform like any other.
Architecture: amd64 or arm64.

Prerequisites

Platform

Thinkube running, with Thinkube IDE open. Ask Claude: "what’s running?"
A repository Tandem knows. The walk made one: "make an app called todo from the web app template". For a repository you already have, run Tandem: Activate Repository.

Components

None beyond the base platform.

Instructions

Step 1. Make the app and open a space

A thinking space is one page where you write your sentences and follow their work. You only ever look at that page.

Ask Claude:

› make an app called todo from the web app template

Claude creates the repository and activates it for Tandem.

Then click the Tandem icon. Under Projects, your repository lists its thinking spaces; choose New thinking space…. The space opens in its own editor tab. Across the top is the strip: one line saying where you are and one button, the next thing you can do.

Step 2. Write your sentences

Type what you want, one line per thing, in the words a person would use. Writing costs nothing: the line under the box says one line is one ask · Enter starts another · Ctrl+Enter reads · nothing is recorded by reading.

Or ask Claude: "put these lines in the box of a new thinking space", followed by the lines. Claude puts the lines in the box.

The nine lines of the walk:

My tasks come back in a sensible order — what is due soonest first, and high priority above low — instead of whatever order the database felt like.
A task that is past its due date is obvious at a glance, not grey small print.
Finished tasks stop crowding the ones I still have to do.
I can see how many tasks I have without counting cards.
I can look at just the high priority ones when I want to.
When I open the new-task box the cursor is already in the title, so I can just type.
I can add a task with the keyboard alone — type a title, press Enter, done.
If I try to save a task with no title it tells me, instead of doing nothing.
Deleting a task asks me first, because one mis-click should not lose work.

The strip then says 9 lines written, not read.

Step 3. Read these 9

Press Read these 9. Every sentence comes back with the two parts the machine read in it: the subject highlighted, the claim (what must become true of it) underlined. What I read in your words lists the subjects, my tasks, the new-task box, deleting a task, with how many claims each carries.

The space after Read these 9: each sentence marked with what it is about and what must become true of it

A sentence that never names its subject shows the subject in brackets and names nothing. If the reading is wrong, change the words and press Read it again.

Step 4. Keep these 9

Press Keep these 9. The page your sentences opens with the nine sentences, each with a pencil to say it differently and a plus to amend it.

Step 5. Group into things to build

Press Group into things to build. Each thing gets a name, the sentences it carries, and a suggested order: first, then, later. Proposing decides nothing.

On the walk the nine sentences became three things:

Thing	Sentences
I can see at a glance what still needs doing	1–5
I can add a task without leaving the keyboard	6–8
I cannot lose a task to a mis-click	9

Thing

Sentences

I can see at a glance what still needs doing

1–5

I can add a task without leaving the keyboard

6–8

I cannot lose a task to a mis-click

Step 6. Build the first

Press Build the first. The strip counts working out what to build — N of M subjects done. When the last subject is done, the page what it will do opens.

Under What will be true when this is done it shows one promise for each claim, the files it lands in, and under each promise the lines that must become true, each with where it stands:

checked when it is built: a check, written before the code by a worker that never sees the code, will prove it;
judged by a reviewer at delivery: a reviewer reads the finished work once;
only you can see this: only the running product can show it, and you confirm it.

Every thing also carries the promise The documentation says what "<the thing>" does, in the words of the person using it. It lands a page in the project’s docs/ folder. Press Not needed on it, with your reason, when no page applies.

Step 7. Sign: Build these N

At the bottom of the work page, Pressing Build these N says what the press does. It signs this work and locks the sentences behind it. It records the machine’s own answers to the open questions. These are the choices your sentences left open, listed as N things I decided for you. It starts the workers and pushes a branch. Nothing is merged until the delivery.

The work page of a thing with one sentence: two promises

Press Build these N. The strip says building — <the thing’s name>, the run page opens, and Stop is the only other button.

Step 8. Watch it build

The page the run shows one card per piece of work, titled with the promise it keeps, with a state word: ready, running, needs you, passed, failed, never ran. The header counts N of M workers done · N of M judged on the running product.

The run page: cards with their state words and log counts

needs you means a worker stopped on a question only you can answer, about what you want. The page offers a box and Send. The run is a process of its own: closing or reloading the window does not end it.

Step 9. Read the report

When the run ends, the strip says where it ended, such as built, deployed and running at <address>. The report opens with one paragraph in plain words, then What you asked for, and what happened: each sentence with a word, and under it the checks that proved it.

The report of the first thing: 23 checks passed

On the walk the first thing ended with 23 checks passed, and the four reviewers on the running product judged 14 lines. Further down, What the work noticed, and did not do lists what the reviewers saw and did not settle.

Step 10. Decide

The buttons at the end are yours:

Go on to the next closes this thing and moves to what is left to build.
Take it back out reverts this delivery’s merges and pushes.
Run it again starts the signed work again; nothing you wrote changes.

Press Go on to the next. The strip offers Build the first for the next thing, and the path from Step 6 repeats. When the last thing is built, the strip says 9 sentences · everything is built and every sentence reads built and accepted — it is in the project.

The space with everything built: three accepted things

Step 11. Next steps

To undo: On the report, press Take it back out.

Build the improvements Tandem’s reviewers suggest: the reviewers' findings as the next sentences.
The words on the page: every state word on the run and the report.

Troubleshooting

Symptom	Cause	Fix
After Claude made the app, Projects still says no repositories yet	The tree reads the repositories when the window loads	Reload the window; the new repository appears with its spaces.
In a freshly opened window, the first click on a space in Projects opens nothing	The extension is still starting	Click again after a few seconds.
Build these N says documentation is needed	Every thing carries a documentation promise, and neither its page nor Not needed is there	Press Not needed on the documentation promise with your reason, or let the page be built.
A card says needs you and nothing moves	A worker stopped on a question only you can answer, about what you want	The card offers a box and Send. The status bar says needs an answer until you do.
The report says "the reviewers are locked out, so none was started"	The reviewers' browser could not sign in to the running product	Open the address yourself and sign in. If that works, press Run it again; the lines they would have judged read not judged until then.
Take it back out is refused and names a commit	A commit of your own, made outside Tandem, sits on top of the delivery	Move that commit aside first; taking the delivery out would take it too.

Symptom

Cause

Fix

After Claude made the app, Projects still says no repositories yet

The tree reads the repositories when the window loads

Reload the window; the new repository appears with its spaces.

In a freshly opened window, the first click on a space in Projects opens nothing

The extension is still starting

Click again after a few seconds.

Build these N says documentation is needed

Every thing carries a documentation promise, and neither its page nor Not needed is there

Press Not needed on the documentation promise with your reason, or let the page be built.

A card says needs you and nothing moves

A worker stopped on a question only you can answer, about what you want

The card offers a box and Send. The status bar says needs an answer until you do.

The report says "the reviewers are locked out, so none was started"

The reviewers' browser could not sign in to the running product

Open the address yourself and sign in. If that works, press Run it again; the lines they would have judged read not judged until then.

Take it back out is refused and names a commit

A commit of your own, made outside Tandem, sits on top of the delivery

Move that commit aside first; taking the delivery out would take it too.