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// Builder

A future workspace for shipping owned projects with AI.

Builder is an early product lane. The demo should feel real enough to communicate the direction, while staying honest that the public surface is still being defined.

Join Builder waitlistRead our vision

The near-term contract is ownership: real files, clear status, export paths, and eventually GitHub/deploy handoff.

Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Builder concept surfaces

Make the future product concrete without overclaiming.

Workspace

Define the browser workspace contract.

Concept

The concept is real project files, real environments, explicit status, and a clean path to owned code.

Join waitlist
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Repo export

Never get locked into a toy DSL.

Concept

Builder should produce projects you can push to GitHub, inspect, deploy, and continue outside AlgoArena.

Preview export
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Benchmark

Every app can inform the model benchmark.

Future

Anonymized outcomes can compare models on real shipping behavior instead of tiny prompt demos.

View benchmark
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

AI loop

Reuse the assessment evidence layer.

Future

Builder can inherit prompt, edit, test, and verification primitives from the assessment workspace.

See Assessments
Session lineage conceptprompt + edit + test

Timeline

Selected evidence

04:12 · asked Rena

Question included constraints and target behavior.

Verification artifact

product-card.spec.ts: 3/3 passing

Ownership

The product should sell trust before magic.

Owned artifacts

The output should be yours.

Repo ownership, export status, and deployment metadata are the product contract, not decoration.

Get early access
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Stack setup

Skip tedious local setup.

The future interface should make scaffolding, environment setup, and dependencies feel boring in the best way.

Read AI notes
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Portability

Host anywhere.

Builder should be compatible with GitHub and ordinary deployment targets, not a closed platform island.

Read vision
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Roadmap links

Builder connects to Assessments, Vibecoding, and Benchmark.

Assessments first

Builder gets easier after OA is polished.

The candidate workspace already needs files, AI modes, tests, and evidence. Builder can reuse that foundation.

Preview Assessments
Candidate workflow conceptnot final UI

Assessment question

Product Card · Design to Spec

Candidate works in one controlled browser tab with a repo, tests, AI mode controls, and replayable evidence.

npm test -- product-card.spec.ts
3 passing / 1 visual check

Evidence captured

planned before prompting
read AI diff before applying
reran failing test
kept model access equal

Vibecoding bridge

Plain-English learners need a place to build.

Vibecoding can eventually graduate learners from commands into real project creation.

Preview Vibecoding
Code bridgeoptional view

Plain English

for every green ball, move it to the green box

for ball in world.balls:
if ball.color == "green":
rena.pick_up(ball)
rena.move_to(green_box)
rena.drop()

Model data

Real projects beat toy evals.

The long-term benchmark should learn from actual build attempts, recovery loops, and accepted outputs.

View benchmark
Builder conceptearly access

Rena Builder

chat to app workspace

You

Build a tiny web app where students track daily algorithm practice and see streaks.

Plan ready

Scaffold Next.js dashboard
Add local progress storage
Generate streak card and goal list
Run smoke check

Rena

I built the first pass. The app has editable goals, a streak counter, and exportable project files.

arena-practice-app4 files
app/page.tsx+84
app/api/progress/route.ts+31
components/GoalCard.tsx+42
lib/storage.ts+18
npm run check
lint passed
preview ready
app/page.tsx
1export default function PracticeTracker() {
2 const goals = ["arrays", "graphs", "dp"];
3
4 return <main className="grid gap-4">
5 <StreakCard days={12} />
6 <GoalList goals={goals} />
7 <RunSummary accepted={8} />
8 </main>;
9}
Browser previewlive

Practice Tracker

June sprint

12 day streak

8

accepted

3

topics

42m

focus

Arrays5/6
Graphs2/4
Dynamic programming1/3
Next suggested build: add reminders and weekly review.

Concept lane

Builder is first-class, even before it is finished.

The page should make the ambition legible: a zero-config AI workspace that outputs owned projects, not screenshots or locked-in artifacts.

Join waitlist