OPT-17: the solar forecast can come from several entities, summed

New list options pv_forecast_entities and pv_forecast_tomorrow_entities
(same shape as pv_entities); the single-entity keys are unchanged.

- Each member is read in its own unit (Wh/kWh/MWh) in one gather and the
  day is summed. Hourly splits are merged when every member has one, else
  the total goes on the bell.
- A member missing, unavailable, stale, non-energy or bad makes that
  day's forecast unusable (no partial sum). A caution row names it by
  position; the action log names the entity once per change.
- Single key and list both set for one day: refused at start.
- A one-member list behaves exactly like the single key (test_opt17.py);
  the single-key path is byte-identical to e36565f over 24 scenarios.
- Supervisor shape measured: tools/supervisor_shape_probe.py section J.

DECISIONS/OPT-17-several-forecast-entities.md has the rules.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/app/validate.py

@@ -1802,12 +1802,13 @@ def _entity_notes(notes, opts: dict, entities: dict, bad=()) -> None:
             _advise(notes, "warn", (key,),
                     f"{entity} does not read in kWh, so pick a solar "
                     "forecast sensor in kWh.")
-    if any(opts.get(k) for k in FORECAST_KEYS) and \
+    today = solarfc.entities(opts)
+    tomorrow = solarfc.entities(opts, tomorrow=True)
+    if (today or tomorrow) and \
             opts.get("battery_modes_enabled") is not True:
         _advise(notes, "info", ("pv_forecast_entity",),
                 "The solar forecast is used only with battery modes on.")
-    if opts.get("pv_forecast_tomorrow_entity") and \
-            not opts.get("pv_forecast_entity"):
+    if tomorrow and not today:
         _advise(notes, "warn", ("pv_forecast_tomorrow_entity",),
                 "Tomorrow's forecast is used only with today's, so set "
                 f"{S('pv_forecast_entity')} too.")
@@ -2069,12 +2070,13 @@ def _margin_problems(opts: dict) -> list[str]:
 TRUST_RANGE_PCT = (30, 100)
 # A Home Assistant sensor id; it goes into the /api/states/<id> path.
 _SENSOR_ID = re.compile(r"sensor\.[a-z0-9_]+")
-FORECAST_KEYS = ("pv_forecast_entity", "pv_forecast_tomorrow_entity")
+FORECAST_KEYS = solarfc.TODAY_KEYS + solarfc.TOMORROW_KEYS
 
 
 def _forecast_problems(opts: dict) -> list[str]:
     """Rule 13 (OPT-11 P4): the trust is a whole percentage in range, and
-    each forecast entity set is a sensor."""
+    each forecast entity set is a sensor. OPT-17: a day names its forecast
+    in the single key or in the list, not both."""
     out = []
     raw = opts.get("solar_trust_pct")
     trust = _number(opts, "solar_trust_pct", dayplan.DEFAULT_TRUST_PCT)
@@ -2082,14 +2084,30 @@ def _forecast_problems(opts: dict) -> list[str]:
     if trust is None or trust != int(trust) or not lo <= trust <= hi:
         out.append(f"{S('solar_trust_pct')} must be a whole number from {lo} "
                    f"to {hi} %. It is {messages.shown(raw)}.")
-    for key in FORECAST_KEYS:
-        e = opts.get(key)
-        if e is None or e == "":
-            continue
-        if not isinstance(e, str) or not _SENSOR_ID.fullmatch(e):
-            out.append(f"{S(key)} must be a sensor, like "
+    for one, many in (solarfc.TODAY_KEYS, solarfc.TOMORROW_KEYS):
+        e = opts.get(one)
+        if e is not None and e != "" and (
+                not isinstance(e, str) or not _SENSOR_ID.fullmatch(e)):
+            out.append(f"{S(one)} must be a sensor, like "
                        f"sensor.energy_production_today_remaining. It is "
                        f"{messages.shown(e)}.")
+        raw = opts.get(many)
+        if raw is None:
+            raw = []
+        if not isinstance(raw, list):
+            out.append(f"{S(many)} must be a list of sensors. It is "
+                       f"{messages.shown(raw)}.")
+            continue
+        listed = [x for x in raw if x is not None
+                  and not (isinstance(x, str) and not x.strip())]
+        for x in listed:
+            if not isinstance(x, str) or not _SENSOR_ID.fullmatch(x):
+                out.append(f"{S(many)} must list only sensors, like "
+                           f"sensor.energy_production_today_remaining. "
+                           f"It has {messages.shown(x)}.")
+        if e and listed:
+            out.append(f"Set {S(one)} or {S(many)}, not both. Keep the "
+                       f"list and clear the single one.")
     return out