display: refresh EPD on WAN interface change and improve WAN detection

[01rabbit]

PR: display: refresh EPD on WAN interface change and improve WAN detection

Summary

This PR improves runtime WAN detection and E-Paper (EPD) rendering behavior. The primary goals are:

• Ensure the E-Paper display is cleared and fully refreshed when the active WAN interface changes (for example eth0 -> wlan1) to avoid ghosting and ensure the new interface/IP is shown immediately.
• Improve WAN detection by preferring the kernel's default route when the runtime WAN state file is not present. Add an injectable wan_state_path for testing and overrides.
• Clean up renderer output: remove a redundant "WAN" prefix, suppress non-actionable "[WAN] unknown" messages, and reserve a footer area to prevent text overlap.
• Make EPaperDaemon initialization tolerant of older StatusCollector signatures (backwards-compatible fallback).

Version was bumped to 3.1.0 and CHANGELOG.md was updated. See commits 478b8ee and eee6e81 for the implementation and release bump.

Changes (high-level)

• azazel_pi/core/display/status_collector.py

  • Accepts an optional wan_state_path argument for injection/testing.
  • If runtime WAN state is missing, attempts to query the kernel default route (e.g. ip route get) to determine the active interface.
  • Changed safe fallback preference to reduce incorrect legacy fallbacks.

• azazel_pi/core/display/epd_daemon.py

  • Tracks last-seen active interface; when interface changes, clears the display and forces a full refresh to avoid ghosting.
  • Initialization is tolerant of older StatusCollector signatures (catches TypeError and retries without the extra param).

• azazel_pi/core/display/renderer.py

  • Removes redundant "WAN" prefix in the network line and suppresses "[WAN] unknown" messages.
  • Reserves footer area and adjusts font sizing to avoid text overlap.

Files changed

• azazel_pi/core/display/status_collector.py
• azazel_pi/core/display/epd_daemon.py
• azazel_pi/core/display/renderer.py
• CHANGELOG.md (added 3.1.0 entry)
• pyproject.toml (version bump to 3.1.0)

Why this is a minor bump (3.0.0 -> 3.1.0)

All changes are backward-compatible runtime improvements and feature additions (no breaking API changes). They primarily improve behavior (EPD UX and detection heuristics), so a minor version increment is appropriate.

How to test (developer / CI)

1. Install test deps and run unit tests (recommended in a virtualenv):

python3 -m venv .venv
source .venv/bin/activate
pip install -U pip
pip install pytest pytest-cov
pytest -v

2. EPD emulation (quick visual smoke test):

# Save relative path from repo root and run the daemon in emulation/test mode
python3 azazel_pi/core/display/epd_daemon.py --mode test --emulate --emulate-output /tmp/epd_test.png
# Open /tmp/epd_test.png with an image viewer to inspect layout and footer

3. Run the daemon in debug mode to see log messages and lifecycle behavior (on-device):

sudo python3 /opt/azazel/azazel_pi/core/display/epd_daemon.py --debug
# or, if testing the workspace copy directly (less privileged):
python3 ./azazel_pi/core/display/epd_daemon.py --debug

4. To test the installed service behavior (systemd):

# If you edit the systemd drop-in to set rotation or other envs:
sudo systemctl daemon-reload
sudo systemctl restart azazel-epd.service
sudo journalctl -u azazel-epd.service -f

# Trigger a WAN interface change on the device (example):
# - unplug/plug the interface, change routing, or run the WAN manager to switch candidate
# While triggering, watch journal output for interface-change detection and EPD clear/refresh logs.

Example log excerpts (observed during development)

These excerpts are representative of the output produced during development and debugging.

TypeError observed before the runtime was updated (illustrates compat fix):

TypeError: StatusCollector.__init__() got an unexpected keyword argument 'wan_state_path'

Daemon startup and update loop messages (normal debug output):

E-Paper daemon starting...
Boot animation suppressed
Update #1: drawing status (force_full=False)
e-Paper busy
e-Paper release
Update #2: drawing status (force_full=False)
...

Interface detection/log example (route-based fallback):

resolved state path: /var/run/azazel/wan_state.json (exists: False)
kernel route probe -> dev eth0
active_interface: eth0 (ip: 192.168.40.14)
wan_state: unknown

When a WAN change is detected the daemon logs a message and forces a clear + full refresh; look for a message similar to:

WAN interface changed: wlan1 -> eth0; clearing display and forcing full refresh

Deployment notes (on-device)

• The installed package path is /opt/azazel/azazel_pi. If you deploy the workspace copy over the installed copy, back up the existing /opt/azazel/azazel_pi first.
• The service uses the azazel-epd.service systemd unit. Rotation and daemon options can be controlled via the systemd drop-in at /etc/systemd/system/azazel-epd.service.d/override.conf using Environment= entries, e.g.: Environment=EPD_ROTATION=180.
• After updating files under /opt, run:

sudo systemctl daemon-reload
sudo systemctl restart azazel-epd.service
sudo journalctl -u azazel-epd.service -f

Checklist for reviewers

• Confirm code is readable and follows project conventions.
• Confirm there are no breaking changes to public APIs or CLI behavior.
• Run unit tests locally or via CI.
• Smoke-test EPD emulation (see above) for layout and footer overlap.
• Verify that interface-switch behavior clears the display on a device.

Commits of interest

• 478b8ee — display: refresh EPD on WAN interface change and improve WAN detection (feature implementation)
• eee6e81 — chore(release): bump version to 3.1.0 (changelog + pyproject)