fix: read saving session available_events from configured entity, not rewritten one

The binary_sensor -> event entity rewrite used as a fallback for legacy
configs rebound entity_id unconditionally whenever joined_events was
empty, so the following available_events read used the rewritten name
instead of the configured entity. If the rewritten entity didn't exist
(e.g. custom entity names with no '_sessions' substring), available_events
came back empty and saving-session auto-join silently stopped working
with nothing logged.

Fixes #4573

Author: springfall2008

apps/predbat/octopus.py

@@ -2940,11 +2940,17 @@ def fetch_octopus_sessions(self, axle_sessions=None):
             if entity_id:
                 state = self.get_arg("octopus_saving_session", False)
                 joined_events = self.get_state_wrapper(entity_id=entity_id, attribute="joined_events")
-                if not joined_events:
-                    entity_id = entity_id.replace("binary_sensor.", "event.").replace("_sessions", "_session_events")
-                    joined_events = self.get_state_wrapper(entity_id=entity_id, attribute="joined_events")
-
                 available_events = self.get_state_wrapper(entity_id=entity_id, attribute="available_events")
+                if not joined_events and not available_events:
+                    # Legacy binary_sensor entities carry neither attribute - fall back to the
+                    # newer event entity naming convention, but only adopt it if it actually has data
+                    fallback_entity_id = entity_id.replace("binary_sensor.", "event.").replace("_sessions", "_session_events")
+                    fallback_joined_events = self.get_state_wrapper(entity_id=fallback_entity_id, attribute="joined_events")
+                    fallback_available_events = self.get_state_wrapper(entity_id=fallback_entity_id, attribute="available_events")
+                    if fallback_joined_events or fallback_available_events:
+                        entity_id = fallback_entity_id
+                        joined_events = fallback_joined_events
+                        available_events = fallback_available_events
 
             if available_events and not self.get_arg("octopus_saving_auto_join", True):
                 self.log("Octopus: Saving session auto-join is disabled, not joining available events")

apps/predbat/tests/test_saving_session.py

@@ -592,6 +592,76 @@ def setup_items():
     return failed
 
 
+def test_saving_session_custom_entity_no_rewrite_match(my_predbat):
+    """
+    Test that available_events is read from the configured entity even when its name
+    does not match the binary_sensor -> event rewrite pattern (no '_sessions' substring),
+    and no rewritten entity exists at all.
+    Covers GitHub issue #4573
+    """
+    print("Test saving session with custom entity name that does not match the rewrite pattern (issue #4573)")
+    ha = my_predbat.ha_interface
+    failed = False
+    date_today = datetime.now().strftime("%Y-%m-%d")
+    tz_offset = int(my_predbat.midnight_utc.tzinfo.utcoffset(my_predbat.midnight_utc).total_seconds() / 3600)
+    tz_offset = f"{tz_offset:02d}"
+
+    # Custom entity name bridging a saving session event. It has no '_sessions' substring
+    # so the legacy binary_sensor -> event rewrite would point at a non-existent entity if
+    # it were ever applied. joined_events is empty (nothing joined yet) but available_events
+    # is populated - this is exactly the state auto-join needs to act on.
+    session_binary = f"""
+state: off
+available_events:
+    - id: 9999
+      start: '{date_today}T18:00:00+{tz_offset}:00'
+      end: '{date_today}T19:00:00+{tz_offset}:00'
+      duration_in_minutes: 60
+      rewarded_octopoints: null
+      octopoints_per_kwh: 505
+      code: EVENT_TEST
+joined_events: []
+friendly_name: Predbat Octopus Power Down For Predbat
+"""
+
+    ha.dummy_items.clear()
+    ha.dummy_items["binary_sensor.predbat_octopus_power_down_for_predbat"] = yaml.safe_load(session_binary)
+    ha.dummy_items["sensor.octopus_free_session"] = {}
+    my_predbat.args["octopus_saving_session"] = "binary_sensor.predbat_octopus_power_down_for_predbat"
+    my_predbat.args["octopus_free_session"] = "sensor.octopus_free_session"
+    if "octopus_free_url" in my_predbat.args:
+        del my_predbat.args["octopus_free_url"]
+    if "octopus_saving_session_join" in my_predbat.args:
+        del my_predbat.args["octopus_saving_session_join"]
+    my_predbat.args["octopus_saving_session_octopoints_per_penny"] = 10
+    # Reset throttle so a join is attempted
+    my_predbat.octopus_last_joined_try = None
+
+    ha.service_store_enable = True
+    ha.service_store = []
+    my_predbat.fetch_octopus_sessions()
+    service_result = ha.get_service_store()
+    ha.service_store_enable = False
+
+    join_calls = [svc for svc in service_result if "join" in svc[0]]
+    if len(join_calls) != 1:
+        print(f"ERROR: Expected 1 join call reading available_events from the configured entity, got {len(join_calls)}: {service_result}")
+        failed = True
+    elif join_calls[0][1].get("entity_id") != "binary_sensor.predbat_octopus_power_down_for_predbat":
+        print(f"ERROR: Expected join call to use the configured entity, got {join_calls[0][1]}")
+        failed = True
+    else:
+        print("  PASS: available_events read from the configured entity despite no rewrite match")
+
+    if not failed:
+        print("PASS: Custom entity name (no rewrite match) auto-join test passed")
+
+    # Restore default throttle state so we do not leak it to other tests
+    my_predbat.octopus_last_joined_try = None
+
+    return failed
+
+
 def test_saving_session_default_rate(my_predbat):
     """
     Test that saving sessions with no octopoints_per_kwh use the default rate

apps/predbat/unit_test.py

@@ -64,7 +64,15 @@
 from tests.test_solax import run_solax_tests
 from tests.test_sigenergy import run_sigenergy_tests
 from tests.test_single_debug import run_single_debug
-from tests.test_saving_session import test_saving_session, test_saving_session_null_octopoints, test_saving_session_notify_config, test_saving_session_default_rate, test_saving_session_axle_conflict, test_saving_session_auto_join_toggle
+from tests.test_saving_session import (
+    test_saving_session,
+    test_saving_session_null_octopoints,
+    test_saving_session_notify_config,
+    test_saving_session_default_rate,
+    test_saving_session_axle_conflict,
+    test_saving_session_auto_join_toggle,
+    test_saving_session_custom_entity_no_rewrite_match,
+)
 from tests.test_secrets import run_secrets_tests
 from tests.test_ge_cloud import test_ge_cloud
 from tests.test_teslemetry import test_teslemetry
@@ -436,6 +444,7 @@ def main():
         ("saving_session_default_rate", test_saving_session_default_rate, "Saving session default rate injection test", False),
         ("saving_session_axle_conflict", test_saving_session_axle_conflict, "Saving session Axle conflict avoidance test (issue #4120)", False),
         ("saving_session_auto_join_toggle", test_saving_session_auto_join_toggle, "Saving session auto-join toggle test (issue #4120)", False),
+        ("saving_session_custom_entity_no_rewrite_match", test_saving_session_custom_entity_no_rewrite_match, "Saving session custom entity no rewrite match test (issue #4573)", False),
         ("alert_feed", test_alert_feed, "Alert feed tests", False),
         ("fox_api", run_fox_api_tests, "Fox API tests", False),
         ("deye_const", run_deye_const_tests, "DEYE constants tests", False),