← BackAI Health Design · 2025

Vela

A health companion for couples — sharing data, not just dashboards.

Solo Designer & Engineer · 3 weeks

Vela — Today view

Health data is everywhere.
None of it travels with the people closest to you.

Couples manage health in parallel — separate apps, separate appointments. When something matters, the person who could help is the last to know.

Connect your data, set your boundaries

Connect your data, set your boundaries

Oura ring, lab results, medical history — imported and organized. Each metric can be shared, summarized, or kept private.

Designed for two people, not one user with a contact list

Designed for two people, not one user with a contact list

The partner invitation is the first meaningful action. Both sides choose exactly what to share before any data moves.

Product

Four tabs. One shared view.

Today

Today

Timeline

Timeline

Coach

Coach

Partner view is the product

Partner view is the product

Switch to your partner's view and the AI reframes everything as actions you can take. A high-readiness day becomes 'a good day to ask him to cook dinner.'

Profile & privacy

Profile & Privacy Controls

Partner connection

Partner Connection

Desktop login

Desktop — Login

Desktop onboarding

Desktop — Onboarding Flow

Process · Decision Points

The hard calls — and what they cost.

The case study above is what shipped. This is how it got there — the screens I redesigned six times, the bets I'd take again, and the things I had to give up to get out the door in three weeks.

Decision · 01

How do you let one partner see the other's body data without it feeling like surveillance?

The partner view is the whole product — but a faithful mirror of someone's biometrics reads as voyeuristic, not caring. I redesigned this screen six times before the reframing landed: every metric is verbed for the viewer, not just shown.

Vela
○ You● Hanna

Hanna · Apr 7

Full health snapshot

85
Sleep
70
Readiness
60
Activity

28

HRV

52

RHR

+0.3

Temp

D18

Cycle

Labs · Mar 28

Vitamin D
24 ng/mLLow
Ferritin
18 ng/mLLow-N
TSH
2.1 mIU/LNorm
Cortisol
19.5 µg/dLHigh-N

Medical history

Hashimoto’s · Levothyroxine 50µg · Endometriosis (stage 2)

today
cycle
coach
you

v1 — Faithful mirror

First pass: just surface everything — rings, vitals, labs, medical history — exactly as the owner sees it. Felt like reading someone's chart.

How do you let one partner see the other's body data without it feeling like surveillance? — v2 — Mobile dual-view

v2 — Mobile dual-view

Moved to mobile, surfaced both partners' rings and a written 'about' summary. More care, but the explanatory paragraph still narrated her body to him.

How do you let one partner see the other's body data without it feeling like surveillance? — v3 — Action pills · shipped

v3 — Action pills · shipped

Every metric is verbed for the viewer. '85 readiness' becomes 'Ask him to cook dinner tonight.' The data is the same — the address changes.

Trade-off

Reframed metrics make the partner view less useful as a longitudinal tracker — you can't easily compare last Tuesday to today. The relationship was worth more than the dashboard.

Decision · 02

Who decides what gets shared — and how do you make the consent feel like a conversation, not a configuration screen?

Sharing biometric data with a partner is the highest-stakes consent flow in the app. I tried defaults that were too open, then a master toggle that was too coarse, before landing on per-metric switches. The control is precise. The negotiation it implies is still one-sided — only the data owner decides.

Vela
● You○ Daniel

Connected to Daniel

You’re sharing health data

Sharing everything

Daniel can now see your sleep, activity, labs, cycle, and medical history.

Continue to Today

You can change this later in Settings

today
cycle
coach
you

v1 — Open by default

Connect partner → all data shared, all the time. Fastest path to value; immediate deal-breaker for testers in conflict-prone or recovering relationships.

Vela
● You○ Daniel

Privacy

Sharing with Daniel

Share my health data

Sleep, activity, labs, cycle, medical history

When off, Daniel sees nothing. There’s no in-between.

today
cycle
coach
you

v2 — Single master switch

One 'share my data' toggle for the whole relationship. Honest about the all-or-nothing trap, but too blunt for the real variety: people want to share rings but not labs, sleep but not cycle.

Vela
● You○ Daniel

Privacy · You

What Daniel sees

Sleep data
Activity data
Lab results
Cycle tracking
Medical history

Each switch is independent. Change anytime.

today
cycle
coach
you

v3 — Per-metric controls · shipped

Each Oura metric gets its own switch with a plain-language explainer. Privacy lives on the You tab, one tap from anywhere in the app.

Trade-off

Per-metric toggles are precise but the consent stays one-sided — the data owner controls what gets shared, the partner just receives. The next version needs both people in the negotiation, with explicit onboarding friction. That's the first thing I'd revisit.

Decision · 03

What does the AI sound like when it's talking about your body?

The Coach speaks dozens of times per week. Clinical voice ("Your sleep quality is below baseline") felt like a chart-review. Friend voice ("Hey buddy! Get more zzz!") infantilised adults managing chronic conditions. I rewrote the prompt three times and still trim every output by hand.

Vela
● You○ Daniel
V

Vela Coach

Online

Sleep quality below baseline.
HRV: 28 ms (33% under 7-day mean of 42).
Cortisol: 19.5 µg/dL — high-normal.
Ferritin: 28 ng/mL — sub-threshold.

Recommendations:
1. Avoid HIIT today.
2. Increase iron intake (red meat, legumes).
3. Sleep onset target: 22:00.

Why iron?

Iron supports oxygen transport via hemoglobin. Sub-threshold ferritin correlates with fatigue (r=0.42, p<0.01).
Refer to clinician for IV supplementation if < 20 ng/mL.

…I already have a doctor for this.

Ask your coach…
today
cycle
coach
you

v1 — Clinical

Doctor's voice — accurate, traceable, but cold enough that one tester said 'I already have a doctor for this.'

Vela
● You○ Daniel
V

Vela Coach

Online

Heyyy Sarah! 👋 Rough night, huh? Don’t worry, we got this!! 💪

Let’s grab some extra zzz’s tonight and CRUSH tomorrow together 🌟

Wanna plan a chill day? I’m here whenever, buddy 💛

…hmm, ok.

Aww, you got this 💕 Sending good vibes your way!! ✨ Wanna talk about it?

No.

Ask your coach…
today
cycle
coach
you

v2 — Friend

Warm, casual, encouraging. Trust collapsed: people wanted authority on health, not cheerleading.

What does the AI sound like when it's talking about your body? — v3 — Editorial care · shipped

v3 — Editorial care · shipped

Informed, present, neither parental nor casual. 'Two short nights stacked. A walk after dinner usually closes that gap for you.'

Trade-off

The editorial voice is hand-tuned per scenario template, not learned from a large dataset. It's the most expensive part of the product to scale to new domains — every condition, every life stage needs a fresh pass.

Process · Design System

The kit underneath.

A small system, not a brand bible. Nine colors, three type roles, and a handful of primitives that compose the entire app.

Colors · 9 tokens

Navy

#0D1424

Background

Card

#1A2436

Surface

Card Hi

#243049

Surface +1

Text

#E5EAF2

Primary text

Muted

#8593A8

Secondary text

Accent

#5BA4F5

Action / link

Green

#4AD4B0

Positive

Warn

#F5A65B

Caution

Alert

#F26B6B

Out of range

Type · 3 roles

Display

Syne / Inter

600–700 · -0.02em · 1.1

Sharing with Daniel

Body

Inter

400 · 0 · 1.5

Each metric is verbed for the viewer. Data is the same — the address changes.

Data

JetBrains Mono

500 · 0.04em · 1.4

HRV 28ms · Cortisol 19.5 µg/dL · Ferritin 28 ng/mL

Primitives · 6
● You○ Hanna

Partner toggle

Sleep data
Lab results

Per-metric toggle

85
Sleep
70
Readiness
60
Activity

Ring metric

Ask him to cook dinner tonight

Readiness 85 — he has the energy for it

›

Action pill (partner view)

Vitamin D
24 ng/mLLow
TSH
2.1 mIU/LNorm
Cortisol
19.5 µg/dLHigh-N

Lab status row

Two short nights stacked. A walk after dinner usually closes that gap for you.

Coach voice (editorial)

Principles · 4

Numbers are bodies

Data is set in mono and quoted, never decorated. A lab value is information, not a brand element.

Verbs over numerics

In partner view, every metric resolves to an action. The viewer never has to interpret.

One accent, one positive

Blue is the only interactive color. Green is the only celebratory color. Everything else is type.

Privacy is one tap

Sharing controls live on the same screen as personal data — never buried in settings.

Stack & Tools

AI

Claude (Sonnet + Opus)
Claude Code

design

Figma

code

Next.js 16
TypeScript
Tailwind CSS

infra

Supabase
Oura API
Anthropic SDK
Vercel

Reflection

What I'd revisit

The privacy model works but needs onboarding friction — partners should negotiate sharing levels explicitly. The coach also needs evaluation beyond satisfaction: tracking override rate and suggestion-to-action conversion.

Next

Tend