frame/CLAUDE.md

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# CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
## What This Is
An e-ink photo frame that runs on a Raspberry Pi Zero 2W. It fetches photos from an Immich server, checks Home Assistant for presence (only displays when someone is home), and renders them on a Waveshare 7.3" 6-color e-Paper display (800x480, ACeP technology with Black/White/Yellow/Red/Blue/Green).
## Deployment
```bash
./sync.sh # rsync src/ to andras@192.168.0.81:~/frame/
```
On the Pi:
```bash
cd ~/frame
python3 display.py # default: photos of Me,Ruby
python3 display.py --album "Album Name" # from specific album
python3 display.py -o 90 # portrait mode (90° or 270°)
python3 display.py --saturation 1.5 --contrast 1.1 --gamma 0.85
```
## Architecture
**`src/display.py`** — Entry point. Orchestrates the pipeline:
1. Checks time (skips between midnight7am)
2. Checks Home Assistant presence (skips if nobody home)
3. Fetches a random photo from Immich (by people or album)
4. Sends to e-ink display driver
**`src/lib/immich.py`** — Immich API client. Key behaviors:
- `PhotoHistory` tracks displayed photos in `photo_history.json` to avoid repeats (resets after 7 days). Asset is only marked displayed after a successful download.
- `_pick_weighted_random()` biases selection: 20% favorites, 50% recently-added (last 30 days, by Immich `createdAt`), otherwise uniform random
- Filters photos by orientation (portrait/landscape) based on EXIF data including rotation tags. Raises if nothing matches the requested orientation.
- Downloads preview-size thumbnails, not originals
- Asset lists (people-search and album) are cached on disk in `/tmp/frame_cache/` for 1 hour
- `urlopen` calls retry transient failures twice (3s, 10s backoff)
**`src/lib/homeassistant.py`** — Simple Home Assistant REST client for presence detection.
**`src/lib/waveshare_epd/epd7in3e.py`** — Modified Waveshare driver. The `getbuffer()` method handles the full image pipeline:
- Center-crops to 800x480 (or 480x800)
- Enhances saturation/contrast/gamma for e-ink (caller passes values; CLI defaults live in `display.py`: saturation=1.3, contrast=1.05, gamma=0.90)
- Atkinson dithering to 6-color palette using numba JIT; produces palette indices directly (no Pillow quantize round-trip)
- Packs into 4-bit-per-pixel buffer (two pixels per byte) via numpy
**`src/lib/waveshare_epd/epdconfig.py`** — GPIO/SPI hardware config. **Critical: PWR pin is BCM 27** (not default 18).
**`src/lib/progress.py`** — Simple terminal progress bar.
## Key Constraints
- **Always call `epd.sleep()` after display** — the driver uses a try/finally pattern for this
- **Display refresh takes 12-15 seconds** — the BUSY pin polling handles this
- **No test suite** — this is a hardware project; test by deploying to the Pi
- **Dependencies on Pi**: `python3-pil python3-opencv python3-numba python3-smbus spidev gpiozero`
- **Config via environment variables**: `IMMICH_URL`, `IMMICH_API_KEY`, `HA_URL`, `HA_TOKEN` (with hardcoded defaults in display.py)
- **Uses only stdlib `urllib`** — no requests library; the Immich client uses `urllib.request` directly
- **Single-instance lock** at `/tmp/frame.lock` (fcntl) — overlapping cron runs exit cleanly
- `sys.path.append` is used to add `lib/` to the path from display.py