# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [1.9.1] - 2026-01-03

### Fixed
- **CRITICAL**: WiFi startup sequence - synchronous connection in setup() to ensure proper initialization order
- Display blank screen for 10+ seconds on boot (now shows time after ~15 seconds)
- "DNS resolution failed" errors during startup
- Sunrise/sunset labels cut off on 128px screen (removed labels, arrows are self-explanatory)

### Changed
- Hybrid WiFi model: synchronous in setup(), async reconnect in loop()
- Display formatting: superscript degree symbol and lowercase 'c' for temperature
- Sunrise/sunset screen now shows daylight duration (e.g., "Day 9h 41m") instead of static "Sun Times" text

### Documentation
- Added detailed v1.9.1_HYBRID_FIX.md explaining startup sequence problem and solution

## [1.9.0] - 2026-01-02

### Added
- Fully async architecture (zero blocking operations in loop)
- Custom async NTP implementation (manual UDP packet handling)
- Async HTTP weather fetch (AsyncHTTPRequest library)
- Exponential backoff retry logic for network failures
- Independent epoch tracking for accurate time between NTP syncs

### Changed
- Replaced blocking NTPClient with custom async UDP implementation
- Replaced blocking HTTP weather with AsyncHTTPRequest
- Removed all delay() calls from loop()
- WiFi connection now async (later fixed in v1.9.1)

### Performance
- Loop time: 10ms → <1ms (10x improvement)
- Weather fetch: 1-10s blocking → 0ms
- NTP sync: 5-20s blocking → 0ms
- WiFi reconnect: 15s blocking → 0ms
- OTA updates now work during active weather fetching

### Technical
- RAM usage: +536 bytes (36,980 → 37,516)
- Flash usage: +1040 bytes (407,500 → 408,540)
- IRAM: 61,987 bytes (94% - stable)

## [1.8.0] - 2026-01-01

### Security
- **CRITICAL**: Removed hardcoded WiFi credentials
- Integrated WiFiManager for secure captive portal setup
- Added config validation (magic number check)
- Input sanitization to prevent buffer overflows

### Fixed
- IRAM overflow crisis (94% → 70% via ICACHE_FLASH_ATTR)
- NTP interval bug (config value was ignored, always used hardcoded 1 hour)
- Boolean parsing errors in JSON config import/export
- Infinite loop protection in display mode rotation
- Memory leaks from String concatenation in web handlers

### Changed
- Web responses now use chunked transfer (eliminated 140+ String concatenations)
- Applied ICACHE_FLASH_ATTR to 26 functions (moved code from IRAM to Flash)
- Improved error handling throughout codebase

### Performance
- Peak heap usage reduced by ~8KB
- EEPROM validation prevents loading corrupted config

## [1.7.0] - 2025-12-31

### Added
- Initial working firmware with correct display support
- NTP time synchronization
- Weather data from Open-Meteo API (free, no API key required)
- OTA update support (web-based and ArduinoOTA)
- Web interface (/, /config, /debug, /update)
- REST API (time, status, weather, config export/import)
- Display rotation (time, weather, sunrise/sunset modes)
- Timezone support with manual DST configuration
- EEPROM configuration persistence

### Hardware Discovery
- Identified display as GM009605v4.3 (not TM1637 or TM1650)
- Discovered swapped I2C pins: SDA=GPIO0, SCL=GPIO2
- Switched to Adafruit_SSD1306 library

### Replaced
- QWeather API → Open-Meteo (no registration required)
- Proprietary firmware → Open source custom firmware
- Insecure WiFi handling → WiFiManager with timeout

## [1.6.0] - 2025-12-30 (unreleased)

### Attempted
- TM1650 LED driver support (incorrect - device has OLED)

## [1.5.0] - 2025-12-29 (unreleased)

### Attempted
- TM1637 7-segment display support (incorrect - device has OLED)

---

## Version Numbering

- **Major version** (X.0.0): Breaking changes, incompatible config format
- **Minor version** (1.X.0): New features, backward-compatible
- **Patch version** (1.9.X): Bug fixes, no new features

## Links

- [Full v1.9 Release Notes](docs/v1.9_RELEASE_NOTES.md)
- [v1.9.1 Hybrid Fix Details](docs/v1.9.1_HYBRID_FIX.md)

---

**Status**: v1.9.1 is production-ready and actively used 24/7.