fix: re-run automatic_config when tariff structure changes

[mgazza]

Summary

• Fixes export rates stuck at 0.0 when a PredBat pod starts before an Octopus export tariff agreement becomes active
• automatic_config() only runs on first=True and never re-runs when async_find_tariffs() discovers the export tariff later
• Captures tariff keys before/after discovery and re-runs automatic_config() if the key set changed (e.g. "export" appeared)

Details

When async_find_tariffs() runs every 30 minutes and discovers a newly-active export agreement, the tariff keys change (e.g. {"import"} → {"import", "export"}). This triggers automatic_config() to set the metric_octopus_export entity name arg, which was previously never set because the export tariff didn't exist at startup.

The fix is safe because:

• set_arg() is idempotent (simple dict assignment)
• automatic_config() only sets sensor entity names — no side effects
• First-run path unchanged (first=True at line 429-430 still works)
• Only triggers when tariff keys actually change, not every 30-min cycle
• Skips the very first run (when self.tariffs is empty {}) since first=True already handles that

Fixes #3486

Test plan

• Verify existing tariff discovery works unchanged (import-only account)
• Verify export tariff appearing after startup triggers reconfiguration log message
• Verify metric_octopus_export gets set correctly after reconfiguration
• Verify no reconfiguration on subsequent cycles when tariffs haven't changed

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Updates the Octopus integration to re-run auto-configuration when the discovered tariff key set changes at runtime (e.g., when an export agreement becomes active after PredBat has already started), so PredBat can start using newly-available Octopus export rate entities without requiring a restart.

Changes:

• Capture the previously-known tariff keys before discovery and compare them to the newly-discovered keys.
• When the tariff key set changes and automatic is enabled, log the change and re-run automatic_config().

[Copilot]

The old_tariff_keys guard means automatic_config() will not run when tariffs transition from empty {} to non-empty on a later cycle (e.g., no active agreements/API data on first run or a temporary gap, then tariffs appear). In that case, metrics like metric_octopus_import/export can remain unset until restart. Consider tracking whether automatic_config() has already been executed (or passing first into async_find_tariffs) and triggering reconfiguration on any keyset change, including empty → non-empty, while still avoiding duplicate runs on the initial startup path.

Suggested change

	if old_tariff_keys and new_tariff_keys != old_tariff_keys and self.automatic:
	if new_tariff_keys != old_tariff_keys and self.automatic:

[Copilot]

This change introduces new runtime behavior (re-running automatic_config() when tariff keys change) but there doesn’t appear to be test coverage for the automatic=True path in async_find_tariffs(). Adding a unit test that simulates tariffs changing (e.g. {'import'} → {'import','export'}) and asserts automatic_config() is invoked would help prevent regressions.

Suggested change

	if old_tariff_keys and new_tariff_keys != old_tariff_keys and self.automatic:
	if old_tariff_keys and new_tariff_keys != old_tariff_keys and getattr(self, "automatic", False) and hasattr(self, "automatic_config"):