AI-assisted development
Build Notes
Product Build Notes
Development records covering launch decisions, AI-assisted workflows, store publishing, UI experiments, and what changed between iterations.
Store publishing
UX improvements
Product decisions
Build journal by product
| Product | Development focus | Platforms | Read notes |
|---|---|---|---|
| Hallo German | Why native Android / Learning data structure / Device features | Android | |
| Hallo German Coach | Real-life conversation focus / Speaking and review loop / AI custom scenarios | Android · iPhone · iPad | |
| Sseuri Seuljjeok (Pocket Drift) | From ledger to awareness / Local-first personal data / Import and analysis support | Android · iPhone | |
| Lotto Sago Sipeunnal (Lucky Lotto Day) | Beyond a generator / Local-first records / Release constraint | Android · iPhone | |
| QR Scan4u | Air-Gapped Optical Data Transfer / Precision Camera Control & Lens Resilience / Privacy-First Architecture | Android · iPhone · Windows | |
| Bongtu Guide: Korean Gift Money Calculator | Lifestyle / Utility | iPhone | |
| SwiftBeam: Any Device Transfer | Multiple transfer routes / Mixed-device reality / Release packaging | Android · iPhone · Windows · macOS | |
| AI Blogger | From Tistory tool to AI Blogger / Desktop plus backend split / Operational safeguards | Windows · macOS | |
| Puzzle Game | Game | Android · iPhone · iPad | |
| Whack-a-Mole Game | Game | Android · iPhone · iPad | |
| Crypto Futures Auto Trading App | Finance | Windows · macOS · Web | |
| Dividend Stock Management App | Finance | Android · iPhone · iPad · macOS · Windows |
- Platforms
- Android
- Technology
- KotlinJetpack ComposeHiltRoomDataStoreML Kit
Live / Education
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.
- Platforms
- Android · iPhone · iPad
- Technology
- FlutterDartAI ConversationSpeech RecognitionSpaced Repetition
Live / Education
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.
- Platforms
- Android · iPhone
- Technology
- FlutterDartRiverpodSQLiteLocal NotificationsLocal AuthAI Import
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.
- Platforms
- Android · iPhone
- Technology
- FlutterDartRiverpodHiveNotificationsQR Scanner
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.
- Platforms
- Android · iPhone · Windows
- Technology
- FlutterDartQFT Optical ProtocolAir-Gapped TransferCamera Stream ProcessingIsar Database
Live / Productivity / Tools
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, enabling file transfer without a network connection.
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, reducing reliance on external transfer services.
- Platforms
- iPhone
- Technology
- FlutterRules EngineLocal DataForm UX
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
Implementation note
Dark-mode optimized iOS store presentation
- Platforms
- Android · iPhone · Windows · macOS
- Technology
- FlutterDartRiverpodNearby/Wi-Fi DirectFTP/Web PortalLocal Network
Live / Utility
SwiftBeam: Any Device Transfer
Explores frictionless local sharing across phones and desktops.
For the detailed build story, refer to the blog.
Blog StoryMultiple transfer routes
The hard part was not a single fast path, but deciding what should happen when two devices cannot use the same path. The coordinator chooses between Nearby, Wi-Fi Direct, LAN TCP, FTP, web portal, and manual fallback routes.
Mixed-device reality
Phones and desktops have different permissions and network behavior, so QR connection, receiver confirmation, progress states, overwrite/skip/cancel handling, and browser fallback are treated as first-class product flows.
Release packaging
Mobile store releases and desktop downloads were prepared together, which made versioned Windows installer, portable package, macOS archive, and store badges part of the same product delivery story.
- Platforms
- Windows · macOS
- Technology
- ElectronPythonPlaywrightGeminiOpenAITistory/Naver
Built / Productivity / Tools
AI Blogger
Turns AI-assisted blog writing into a controlled desktop publishing workflow.
For the detailed build story, refer to the blog.
Blog StoryFrom Tistory tool to AI Blogger
The product name and scope changed because the workflow expanded from Tistory-only publishing into a broader desktop system that can manage both Tistory and Naver blog operations.
Desktop plus backend split
Electron owns the dashboard, settings, preview, licensing, and packaged app flow, while the Python backend handles browser automation, platform login, publishing commands, and AI-assisted generation work.
Operational safeguards
Local JSON stores, SafeStorage, session files, preview mode, publishing history, and category templates were added because blog automation needs reviewability and recovery, not just one-click generation.
- Platforms
- Android · iPhone · iPad
- Technology
- FlutterAnimationGame Logic
Built / Game
Puzzle Game
An interaction study around tactile puzzle assembly.
Implementation note
Custom interaction logic
Implementation note
Animation tuning for responsiveness
- Platforms
- Android · iPhone · iPad
- Technology
- FlutterGame LoopAudio Feedback
Built / Game
Whack-a-Mole Game
A compact timing and feedback experiment.
Implementation note
State-driven game flow
Implementation note
Lightweight interaction performance tuning
- Platforms
- Windows · macOS · Web
- Technology
- Trading APIsAutomationData Visualization
Built / Finance
Crypto Futures Auto Trading App
A structured dashboard experiment for strategy visibility.
Implementation note
API-connected architecture
Implementation note
Reliability and operational clarity prioritized
Implementation note
Security-aware product thinking
- Platforms
- Android · iPhone · iPad · macOS · Windows
- Technology
- FlutterPortfolio TrackingCharts
Built / Finance
Dividend Stock Management App
Tests clearer portfolio views for dividend-focused tracking.
Implementation note
Cross-platform product thinking
Implementation note
Designed for structured financial information and maintainable feature expansion