Lifelog: a personal operating system built with AI
▶ Live demo · fictitious data, runs entirely in your browser
Lifelog is the system I use every day to run a demanding routine: university, internship, technical studies and preparation for a language certification. It turns a weekly plan into a daily checklist and tracks progress with streaks, charts and checkpoints. Finances, calendar and study notebooks live in the same place.
I built it from scratch with AI, describing what I needed to Claude in natural language and evolving the app one feature at a time as my routine changed, up to the 14 modules shown here.
What it does
| Module | What it is for |
|---|
| Dashboard | Progress ring for the day, streak, weekly focus time, latest mock-exam score, savings and today's priorities |
| Hoje (Today) | The day's checklist, generated from the weekly routine. Unfinished tasks roll over to the next day and priority tasks are marked |
| Rotina (Routine) | Weekly template editor. Some slots rotate topics automatically, e.g. a different SQL, ML or Cloud subject each week |
| Semana / Calendário | Week overview with time per area, plus a monthly calendar with notes |
| Certificação | Mock-exam log for 4 skills (Listening, Reading, Writing, Speaking), with trend chart and target line |
| Gráficos | Custom chart tabs (line, column, comparison, pie) fed by daily metrics |
| Flashcards | Spaced-repetition decks with grading (again / hard / good / easy) |
| Digitação | Rich-text notebooks and an error notebook (wrong → right → rule) |
| Checklists | Reusable, resettable checklists for exam day, essay review and the weekly review |
| Cadernos | Study notebooks per subject (SQL, Python, Statistics, ML, GenAI, Data Engineering, Cloud, BI) with links and review counters |
| Finanças | Monthly cycle (closes on a set day), fixed costs, expenses by category and savings |
| Foco | Pomodoro timer with alarm |
AI features (in the real app)
In the private version, Lifelog runs as a Claude artifact and calls Claude from inside the app:
- Essay grading: scores a written text on 4 criteria, explains each score and lists what to improve.
- Inline writing correction: marks each mistake (grammar, spelling, collocation, word choice) and suggests the fix.
- Daily quote: picks a short, genuinely documented quote about discipline and perseverance.
These calls are disabled in the public demo, which has no AI backend.
Built-in logic worth noting
- Spaced repetition for study topics: completing a SQL, Python, ML or other study task schedules review tasks 1, 3, 7, 14 and 30 days later.
- Rollover and streaks: unfinished tasks move to the next day. A day counts toward the streak when its priority tasks are done.
- Day change detection: if the app stays open past midnight, it generates the new day without a reload.
Screenshots
| Today | Certification tracking |
|---|
| |
How it was built
- AI-first development: every feature was specified in plain language and implemented with Claude, then tested and refined through iterations. Examples: "add a checklist tab", "make Python rotate one sub-topic per week", "don't lose the day if the page stays open overnight".
- Runtime: a single self-contained HTML/CSS/JavaScript file running as a Claude artifact, with a document database (Firestore-style API: collections, documents,
where/orderBy queries).
- No framework: vanilla JS, hand-made SVG charts, responsive layout (sidebar on desktop, bottom tab bar on mobile).
About this demo
- The app code is the same as the real Lifelog. Only the runtime is swapped: a small shim at the top of
index.html re-implements the database API on top of localStorage, so it runs on GitHub Pages.
- All data is fictitious and generated on your first visit: tasks for the last two weeks, mock exams, metrics, expenses and calendar notes. Nothing is sent anywhere.
- To start over, open the browser console and run
lifelogDemoReset().
- AI features and file uploads are disabled, since they need the Claude runtime.
Author: Caio Bandeira · LinkedIn · GitHub
