Fix scheduled refresh not updating correctly and broken default image on first load

[saulob]

Description

This PR improves the refresh logic and fixes stability issues in InkyPi. Fixes #380

Changes

• Process all plugins in the active playlist each cycle
• Fix playlist iteration getting stuck on a single plugin
• Ensure scheduled and interval plugins refresh at the correct time
• Prevent crash when a plugin returns no image
• Add error handling and clearer logging for failed plugins
• Return clear error when plugin fails to generate image
• Add placeholder to avoid broken image on first load
• Auto-reload main page on browser back navigation

Impact

• More reliable and responsive refresh behavior
• No crashes when plugin image generation fails
• Clearer error visibility for plugin failures
• Better UX when navigating back in the browser
• Better handling of initial and error states

[Copilot]

Pull request overview

This PR targets InkyPi’s refresh/playlist behavior and UI resilience, aiming to improve scheduled/interval refresh correctness, avoid crashes when plugins fail to generate images, and improve browser UX when navigating back.

Changes:

• Updates playlist selection/refresh logic in RefreshTask, including skipping/force refresh behavior and additional error handling for missing images.
• Refines PluginInstance.should_refresh() scheduled-refresh behavior for first-run and subsequent runs.
• Improves the main UI page with a first-load placeholder and forces reload on back navigation; adds API error handling when a plugin returns no image.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 6 comments.

File	Description
src/templates/inky.html	Adds back-navigation reload behavior and an image placeholder on load/error.
src/refresh_task.py	Changes playlist iteration and refresh execution behavior; adds handling for None images and more logging.
src/model.py	Adjusts scheduled refresh logic in PluginInstance.should_refresh().
src/blueprints/plugin.py	Returns a clearer API error when generate_image() returns None.

Comments suppressed due to low confidence (1)

src/model.py:325

• The scheduled-refresh check further down also compares scheduled_time (tz-naive) with latest_refresh_dt.time() / current_time.time() (tz-aware). Even after the initial-refresh case is fixed, this block will still raise the same TypeError for scheduled plugins. Consider converting latest_refresh_dt into the same timezone as current_time, then compare full datetimes (date + scheduled wall time) instead of time objects.

        if "scheduled" in self.refresh:
            scheduled_time_str = self.refresh.get("scheduled")
            scheduled_time = datetime.strptime(scheduled_time_str, "%H:%M").time()
            
            latest_refresh_date = latest_refresh_dt.date()
            current_date = current_time.date()

            # Determine if a refresh is needed based on scheduled time and last refresh
            if (latest_refresh_date < current_date and current_time.time() >= scheduled_time) or \
            (latest_refresh_date == current_date and latest_refresh_dt.time() < scheduled_time <= current_time.time()):
                return True

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[saulob]

All Copilot review comments addressed. Fixed timezone handling, separated rotation from refresh logic, ensured cached images are used when not due, reduced log noise, and added pytest coverage. All tests passing, ready for review

[saulob]

I tested this change on a real device throughout the day and the refresh behavior is now working as expected

The system correctly prioritizes plugins based on their due time instead of playlist order, and no longer skips scheduled or interval-based plugins

The refresh cycle is stable and no unnecessary display updates are happening

Logs confirm that the most overdue plugin is always selected, and backlog is processed correctly over time

Example log: