Skip to content

PRD.md

Latest commit

 

History

History
220 lines (158 loc) · 6.87 KB

PRD.md

File metadata and controls

220 lines (158 loc) · 6.87 KB
Raw

PRD — Open Smart Desk

TL;DR

A non-annoying habit system that knows when you've been sitting too long and actually knows if you stood up afterwards. Hardware sensor + Electron tray app. Open source. Mission: change sedentary habits at scale.

Problem

Height-adjustable desks were supposed to fix sedentary work. They didn't. Most sit unused — raised once, forgotten forever.

Root cause: the problem is psychological, not mechanical.

Existing solutions fail because they try to force behavior:

  • Auto-raise desks → users disable after a week (annoying, removes agency)
  • Timer apps (Stretchly, Stand Up!) → ignored after days (notification fatigue)
  • Smartwatch reminders → same pattern

None of them know if you actually stood up. They're blind to your response. We're not.

Solution

A nudge system — not automation. The desk raises when you press the button. We motivate you to press it through context-aware, non-annoying notifications and Duolingo-style habit mechanics.

Key differentiator: we know if you actually stood up (laser sensor measures desk height). Every other reminder app is blind to whether you acted.

Target Users

Primary: Remote developer

  • Works from home, owns a motorized desk
  • Technical enough to install and configure
  • Cares about ergonomics, not just reminded by doctor once a year

Secondary: Coworking user

  • No permanent desk — device travels with them
  • Clips to any desk, calibrates in seconds
  • Data is personal, never shared with coworking space

Non-target (for now)

  • Office employees (fear of employer surveillance — only viable with BYOD + privacy guarantee)
  • People without motorized desks (software-only mode still useful but core value is diminished)

Architecture

RP2040-Tiny + VL53L0X
      │ USB Serial (JSON Lines)
      ▼
[sensor-daemon]                    ← owns the USB port exclusively
  - reads height from laser (1Hz)
  - appends to desk.log CSV        ← crash-safe, flush every line
  - serves WebSocket ws://localhost:3847
  - starts with OS (autostart)
  - never crashes (minimal deps)
      │ WebSocket (localhost)
      ▼
[Electron tray app]                ← can crash freely, daemon doesn't care
  - connects to WS on startup
  - reads OS mouse/keyboard events (presence detection)
  - runs notification state machine
  - sends OS-native notifications
  - shows timeline in tray popup

Two data sources

Signal Source Tells us
Desk height (mm) VL53L0X laser via sensor-daemon sitting / standing
Mouse + keyboard events OS-level listener in Electron app present / away

Two modes

Mode What works What's missing
Hardware mode Full: height + presence Nothing
Software-only Presence only (no height) Don't know if actually standing

Hardware

Component Model Price Source
Microcontroller Waveshare RP2040-Tiny + USB adapter ~20 PLN AliExpress
Laser sensor VL53L0X (ToF, I2C, up to 2m) ~20 PLN AliExpress
PCB Custom black PCB (to be designed) TBD JLCPCB
Enclosure Smoked graphite plexi, laser cut ~20 PLN Local

Total BOM: ~60–80 PLN

Portable. Clips to any desk. USB-powered from host computer.

Notification Algorithm

See full state machine: research/algorithm/NOTIFICATION-ALGORITHM.md

States: AWAY → SITTING → SITTING_ALERT → SITTING_SNOOZED → STANDING

Key rules:

  • Away time does NOT count as sitting (pauses timer)
  • 2 minutes of standing resets the clock
  • Max 3 notifications per sitting session — then gives up quietly, never nags forever
  • No notification when away, standing, or outside working hours
  • Positive copy: "Time for your standing session" not "You've been sitting 2 hours!!"

Gamification (Duolingo-style) — Phase 2

Not in MVP. Added after first 100 active users.

  • Daily streaks (consecutive days with 30+ min standing)
  • XP for each standing session
  • Milestone celebrations
  • Streak protection mechanic
  • Weekly trend: are you improving?
  • End-of-day summary notification

Philosophy: celebrate what you did, never punish what you didn't.

Data & Privacy

  • All data stored locally — ~/.smart-desk/desk.log (CSV)
  • No account, no cloud, no server
  • Opt-in anonymous aggregate upload (for research) — explicit consent only
  • Sensor-daemon logs continuously and crash-safely (append + flush per line)
  • User can export own data as CSV/JSON anytime

MVP Scope

In MVP

  • Sensor-daemon: USB Serial reader + CSV logger + WebSocket server
  • Electron tray app: WS client + mouse/keyboard listener + state machine + OS notification
  • Two modes: hardware (with sensor) and software-only (without)
  • Sitting/standing timeline: today's view in tray popup
  • One config: sitting threshold (default 45 min), working hours

NOT in MVP

  • Streaks / XP / gamification
  • History database (CSV log is enough)
  • Smartwatch integration
  • Calendar integration (meeting detection)
  • Multi-desk support
  • Auto-calibration
  • Manufacturer API
  • Any server/cloud component

Success Metrics

MVP (first 30 days after release)

  • 20+ GitHub stars in first week
  • 5+ people actively using it daily
  • Own data: measurable increase in standing time vs. baseline

Phase 2 (3–6 months)

  • 100+ active users (weekly active)
  • Average standing time: users stand 2x more than before app adoption
  • Retention: 40%+ still active after 30 days

Phase 3 (1–2 years)

  • First manufacturer partnership conversation
  • Academic study in progress (PW or similar)
  • 500+ active users providing aggregate data

What We Are NOT Building

  • An auto-raise desk controller (removes user agency → users disable it)
  • An employer surveillance tool (employees won't use it)
  • A medical device (we are not doctors, no clinical claims)
  • A replacement for ergonomic consultation
  • A mobile app (desktop tray is the right UX for this)

Long-term Vision

Smart Desk → Smart Move (full-day activity coaching) → AI health companion that knows your physical state throughout the day and genuinely helps you take care of yourself.

Business model: open source software + OEM sensor module sold per-unit to desk manufacturers. See research/vision/ECOSYSTEM.md.

Full vision: research/vision/LONG-TERM-VISION.md

Open Questions

  • Notification copy — final wording (needs native English speaker review)
  • Sitting threshold default: 45 min or configurable from first launch?
  • Software-only mode: show "posture unknown" or just track active time?
  • CSV format: one row per second or one row per state change?
  • Autostart: Task Scheduler (Windows) + systemd (Linux) + LaunchAgent (macOS)?
  • WebSocket port: 3847 — any conflicts? Should it be configurable?