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111 lines
5.7 KiB
Markdown
111 lines
5.7 KiB
Markdown
# CLAUDE.md
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## Project Overview
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Look4Sat is an open-source, fully offline Android satellite tracker and pass predictor. It tracks 9000+ active
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satellites using TLE/OMM data from Celestrak/SatNOGS, calculates orbital positions via SGP4/SDP4 models, and displays
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passes relative to the user's location. Features include polar radar visualization, SSTV image decoding, satellite
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ground track mapping, and pass predictions up to 10 days ahead. No ads, no tracking, no network required after initial
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data download.
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## Architecture
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**MVI (Model-View-Intent)** with unidirectional data flow:
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- `State` data class → exposed via `StateFlow` from ViewModel
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- `Action` sealed interface → user intents dispatched to ViewModel's `onAction()`
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- Jetpack Compose UI observes state and recomposes reactively
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**Clean Architecture layers:**
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| Module | Responsibility |
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|--------------------------|-----------------------------------------------------------------------|
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| `app` | Entry point. Aggregates all modules |
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| `core:data` | Android library. Room DB, OkHttp networking, repo implementations |
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| `core:domain` | Pure Kotlin (JVM). Orbital math (SGP4/SDP4), models, repo contracts |
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| `core:presentation` | Android library. Compose theme, shared UI components, NavKeys |
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| `feature:map` | OSMDroid map with ground tracks |
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| `feature:passes` | Pass predictions and upcoming events |
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| `feature:radar` | Polar radar view of satellite positions, SSTV image decoding |
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| `feature:satellites` | Satellite list, filtering, selection |
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| `feature:settings` | User preferences |
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| ------------------------ | --------------------------------------------------------------------- |
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- `feature:*` modules depend only on `core:domain` + `core:presentation`. Features never depend on each other.
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## Build & Run
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```shell
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# Debug build
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./gradlew assembleDebug
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# Release build (minified, shrunk resources)
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./gradlew assembleRelease
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# Run tests
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./gradlew test
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```
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- **Min SDK**: 24 | **Target SDK**: 36 | **JDK**: 17
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- **Gradle**: Uses version catalog (`gradle/libs.versions.toml`) + convention plugins in `build-logic/`
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## Key Libraries
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- **Compose** (BOM 2026.05.01) + Material3 Adaptive
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- **Navigation3** (type-safe, uses `@Serializable` NavKeys)
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- **Room** (KSP code generation) for local satellite/TLE storage
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- **OkHttp** 5.x for TLE downloads
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- **OSMDroid** for map rendering
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- **Kotlin Serialization** for navigation args and data parsing
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- **Coroutines** + `StateFlow` for async/reactive patterns
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## Conventions
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- **Minimal dependencies**: Avoid adding libraries when a simple manual solution exists. Fewer deps = less maintenance.
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- **DI**: Manual — ViewModels use companion `factory()` methods with `IMainContainer` interface.
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- **Navigation**: Type-safe Compose Navigation3 with `@Serializable` data classes as nav keys.
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- **State naming**: `<Feature>State` data class + `<Feature>Action` sealed interface per feature.
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- **No feature-to-feature deps**: All cross-feature communication goes through core layers.
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- **Localization**: 7 languages (en, es, ru, si, tr, uk, zh).
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## Data Formats & Migration
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**TLE vs. OMM/CSV format:**
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Look4Sat supports both TLE and OMM (Orbit Mean-Elements Message) formats for backward compatibility:
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- **TLE format**: Traditional 3-line element format (deprecated). NORAD catalog numbers are 5-digit integers, which
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are running out of space. Celestrak has signaled that TLE format will eventually be phased out.
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- **OMM/CSV format**: The future standard. CSV files contain the same orbital parameters as TLE but use ISO 8601
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timestamps and support larger NORAD IDs. Celestrak and SatNOGS already provide OMM data in CSV format.
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**Current implementation:**
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- `DataParser.kt` handles both `parseTLEStream()` and `parseCSVStream()` seamlessly
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- TLE data is downloaded from configured sources and stored in Room database
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- When downloading satellite data, the app automatically detects format and parses accordingly
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- Both formats produce identical `OrbitalData` objects, ensuring transparent format switching
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**Migration path:**
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As NORAD catalog space becomes constrained, OMM/CSV will become the primary format. Look4Sat is already positioned
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to handle this transition without code changes—existing users can continue using TLE files while new sources transition
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to OMM/CSV automatically.
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## Code Style
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- Prefer **short, focused functions** — single responsibility, easy to read.
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- **Exceptions**: Composable functions and math-heavy algorithms (SGP4/SDP4) may be longer.
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- Strict code style — no dead code, no unused imports, consistent formatting.
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## Roadmap
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- **KMP migration**: `core:domain` is to become a fully shareable KMM module. Keep it pure Kotlin/JVM.
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## Gotchas
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- Orbital math lives in `core:domain/predict/` — it's dense vector math (SGP4/SDP4). Tread carefully.
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- TLE/OMM data must be refreshed weekly for accurate predictions (satellite orbits decay). TLE format is legacy and
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will eventually be deprecated in favor of OMM/CSV as NORAD catalog numbers approach the 5-digit limit.
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- SSTV decoding in `feature:radar` is experimental; image quality depends on signal strength during satellite pass.
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- `build-logic/convention/` contains all shared Gradle configuration — edit there, not in individual modules.
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- ProGuard is enabled for release builds — don't add reflection-based libs or any other dependencies without asking.
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