AI-assisted coding workflow
Build Notes
Product Build Notes
Development records covering launch decisions, AI-assisted workflows, store publishing, UI experiments, and what changed between iterations.
Play Store publishing notes
UI/UX iteration logs
Product journey writeups
LIVE / Language Learning
Hallo German
Designed for lightweight practical German learning.
For the detailed build story, refer to the blog.
Blog StoryWhy native Android
The product needed smooth daily learning screens, offline-friendly progress, and Android-specific language input flows, so it was built as a Kotlin and Jetpack Compose app instead of a generic cross-platform prototype.
Learning data structure
Words and sentences are organized by level and topic, then connected to flashcards, listening, reading, writing, speaking-oriented practice, notebook review, and learning-history screens.
Device features
Room and DataStore keep local study state stable, while ML Kit dependencies prepare OCR, translation, and handwriting recognition paths for learners who want to capture study material from the real world.
LIVE / Language Learning
Hallo German Coach
Practice real-life German conversations and add custom AI scenarios.
For the detailed build story, refer to the blog.
Blog StoryReal-life conversation focus
The product is framed around situations learners may actually face in Germany: housing, work, doctors, pharmacies, public offices, shopping, restaurants, transport, travel, and moments when they need help quickly.
Speaking and review loop
Listening, speaking aloud, speech-recognition comparison, saved expressions, spaced repetition, writing practice, and reminders are connected so learners can return to useful sentences instead of studying once and forgetting them.
AI custom scenarios
Optional AI features let users connect their own OpenAI or Gemini API key to generate personal conversation situations or feedback, while basic learning progress remains local-first by default.
LIVE / Lifestyle Utility
Sseuri Seuljjeok (Pocket Drift)
Tracks daily spending and turns optional purchases into reflection moments.
From ledger to awareness
The product is shaped less like a heavy finance dashboard and more like a daily spending diary: calendar, no-spend days, spending reasons, and reflection prompts make small purchases easier to notice.
Local-first personal data
Expense records, categories, settings, reflection state, and automatic backups are kept on device by default, with manual export and restore paths for users who want control over their own data.
Import and analysis support
The app includes AI-assisted import guidance, exchange-rate conversion, budget checks, trend analysis, and food-spending indicators so existing records can become useful without requiring an account system.
LIVE / Utility
Lotto Sago Sipeunnal (Lucky Lotto Day)
Built around fast repeat use and clear number generation.
For the detailed build story, refer to the blog.
Blog StoryBeyond a generator
The app started from quick number generation, but the product shape became stronger when saved sets, draw results, QR scan history, reminders, and winning-store context were treated as one weekly lotto workflow.
Local-first records
Hive boxes are used for generated sets, result history, scan history, and store data so users can return to previous combinations and checks without depending on a heavy account system.
Release constraint
Store publishing exposed a practical country-availability issue: Korea is a future launch target, but it is currently excluded because of app rating constraints that need to be resolved first.
LIVE / Scanner & File Transfer
QR Scan4u
Scans, generates, and transfers data through camera-first, network-independent workflows.
For the detailed build story, refer to the blog.
Blog StoryAir-Gapped Optical Data Transfer
Conventional wireless transfer methods (AirDrop, Nearby Share, LAN sockets) frequently fail in enterprise, air-gapped, or restrictive corporate networks where devices reside on isolated subnets or block peer-to-peer ports. QR Scan4u implements the QFT protocol to turn computer screens into high-frequency optical transmitters and smartphone cameras into receivers, bypassing all network security constraints with pure optical physics.
Precision Camera Control & Lens Resilience
Industrial and daily scanning demands instant responsiveness. The camera pipeline integrates continuous autofocus, manual torch toggling, one-tap step zoom (2x-5x), and a dedicated lens reset mechanism that instantly re-initializes sensor feeds if the OS camera subsystem stalls.
Privacy-First Architecture
All history records, generated QR codes, and transferred files remain strictly on the local device. No external cloud analytics or intermediate relays are used, delivering complete peace of mind in high-security environments.
LIVE / Lifestyle Utility
Bongtu Guide: Korean Gift Money Calculator
Guides Korean gift money decisions with occasion, relationship, budget, and records.
Implementation note
Flutter mobile app focused on low-friction form UX
Implementation note
Rule-based recommendation structure for occasion and relationship context
Implementation note
Local-first records for past gift money decisions