fix(predheat): say in the log when Predheat is disabled (#4670)

[springfall2008]

Fixes #4670

Problem

Predheat initialises, logs Predheat: Startup and Predheat: Next run time will be ... and then every 300 seconds, and is then completely silent forever — no Predheat: update at ..., no predheat.* entities.

Both timer callbacks open with a silent early return:

if not self.get_arg("predheat_enable"):
    return

So "Predheat is switched off" and "Predheat's scheduler is broken" produce byte-for-byte identical logs. There is no way to tell them apart from a log, which is why #4670 could not be resolved from the reporter's evidence.

Root cause of #4670 itself

Every other link in the chain checks out, verified against the real code and on a live add-on instance:

Link	Result
initialize() registers both timers in run_list	✅ both, run_every 300s
Hass.timer_tick() dispatches them	✅
HA switch event → config value → gate	✅ Predheat ran 3s after the toggle
predheat_enable restored from predbat_config.json across a restart	✅

That leaves the gate as the only thing that can produce total silence, i.e. Predbat's stored predheat_enable is False while Home Assistant's entity displays on — the HA toggle never reached Predbat. When it does arrive, the log already records it (switch_event: switch.predbat_predheat_enable = True) and Predheat runs seconds later. The reporter's "restarting returns the switch to OFF" note is the same desync seen from the other side.

Not a v8.52.0 regression: predheat.py has had no functional change since April, the only commit since being an ERROR:→Error: string tidy.

Change

is_enabled() logs each change of state once (not per tick), naming the switch:

Predheat: Disabled - turn on switch.predbat_predheat_enable to run it
Predheat: Enabled via switch.predbat_predheat_enable, will update every 5 minutes

Re-enabling also sets update_pending, so turning the switch on runs Predheat immediately instead of appearing dead for up to run_every minutes.

Tests

First Predheat tests in the repo (./run_all --test predheat) — timer registration, the silent-gate regression, enabling via the real switch_event path, and the prompt re-enable. Confirmed RED before the fix.

• ./run_all --quick — 816 passed, 0 failed
• ./run_pre_commit — all hooks passed

🤖 Generated with Claude Code

[Copilot]

🟡 Changes recommended

The new Predheat test helper uses datetime.now() for next_time even though timer_tick() requires now > next_time, which can make the test timing-dependent and should be made deterministic.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR improves Predheat operability by making “Predheat disabled” explicitly visible in logs (so it’s distinguishable from a broken scheduler) and adds initial regression tests to cover the enable/disable gate and scheduler behavior.

Changes:

• Add PredHeat.is_enabled() to log enable/disable transitions once and request a prompt update when re-enabled.
• Add a new predheat unit test covering timer registration, the silent-gate regression, and switch-event enable/disable behavior.
• Update Predheat documentation to explain the enable switch behavior and how to diagnose switch desync.

File summaries

File	Description
docs/predheat.md	Documents the “configured but disabled” log behavior and troubleshooting steps.
apps/predbat/predheat.py	Adds state-transition logging for predheat_enable and triggers prompt updates on re-enable.
apps/predbat/unit_test.py	Registers the new predheat test in the test runner.
apps/predbat/tests/test_predheat.py	Introduces tests for scheduler registration and the predheat_enable gate behavior.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 2
• Review effort level: Lite

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