SMA-10: two idle states, hold 0 W or hand the inverter back

A driver now says whether its release() hands the inverter back
(Driver.hands_back; GoodWe is False, so release() stays write(0) and the
Controller never calls it). command_site_release() sits next to
command_site_zero(): the Stop button and shutdown() (so SIGTERM, restart,
control task death and a late config refusal) hand a hand-back unit back,
once, and zero every other unit as before. Safety stops and refusals still
hold 0 W for every unit. Shadow mode releases a hand-back unit. After a
release nothing is written to the unit (heartbeat and cycle included) until
control starts again. release() is bounded by RELEASE_BUDGET_S (= the write
budget), runs concurrently per unit, and a raising or hanging release on one
unit does not stop the others.

The "set to 0 W" sentences for Stop, restart, shadow mode and the stopped
banner are built from the roster (app/handback.py, EN and NL, words from the
driver); a GoodWe-only roster keeps every old literal. A handed-back unit
shows "Back under <its control>" on Home.

Existing test edited: test_messages.py (two classification entries for the
CRITICAL line that moved into a roster builder, and the new release bound).

Co-Authored-By: Claude <noreply@anthropic.com>

goodwe_controller/app/messages.py

@@ -12,6 +12,8 @@ import re
 from dataclasses import dataclass
 from datetime import datetime
 
+from . import handback
+
 # Severity (STYLE.md section 3). An ALARM may use up to three sentences so
 # that no action a person must take is lost; everything else gets one.
 ALARM, WARNING, INFO, RESOLVED = "alarm", "warning", "info", "resolved"
@@ -228,6 +230,19 @@ class Clamp:
     limit: str          # a key of LIMIT_WORDS
 
 
+def _shadow_so(held: str) -> str:
+    """"Shadow mode is on, so <held>." SMA-10: with a unit handed back, the
+    roster's own words say where each unit stays; otherwise `held`, as ever."""
+    moved = handback.shadow_state(handback.current(), "en")
+    return f"Shadow mode is on, so {moved or held}."
+
+
+def _shadow_keeps(held: str) -> str:
+    moved = handback.clause(handback.current(), "en", "at") \
+        if handback.active(handback.current()) else None
+    return moved or held
+
+
 def output_clamp(clamps, *, shadow: bool = False) -> Notice:
     """SAFETY-03: a computed command above the limit. A software fault.
 
@@ -238,7 +253,7 @@ def output_clamp(clamps, *, shadow: bool = False) -> Notice:
     fault = "This is a software fault, so please report it to your installer."
     if not clamps:
         cut = ("would have been cut back" if shadow else "was cut back")
-        state = ("Shadow mode is on, so every inverter stays at 0 W." if shadow
+        state = ((_shadow_so("every inverter stays at 0 W")) if shadow
                  else "Control is still running.")
         return Notice(ID_OUTPUT_CLAMP, ALARM, T_OUTPUT_CLAMP,
                       f"The add-on asked for more power than {RATING} allows "
@@ -250,11 +265,11 @@ def output_clamp(clamps, *, shadow: bool = False) -> Notice:
     if others:
         verb = "was" if len(others) == 1 else "were"
         state = (f"{names(others)} would have been cut too, and shadow mode "
-                 f"keeps every inverter at 0 W." if shadow else
+                 f"keeps {_shadow_keeps('every inverter at 0 W')}." if shadow else
                  f"{names(others)} {verb} cut too, and control is still "
                  f"running.")
     else:
-        state = ("Shadow mode is on, so the inverter stays at 0 W." if shadow
+        state = (_shadow_so("the inverter stays at 0 W") if shadow
                  else "Control is still running.")
     return Notice(ID_OUTPUT_CLAMP, ALARM, T_OUTPUT_CLAMP,
                   f"{who} add-on asked for {watts(c.asked_w)}, above "
@@ -576,6 +591,9 @@ def banner_running() -> str:
 
 
 def banner_stopped() -> str:
+    moved = handback.banner_stopped(handback.current())
+    if moved is not None:       # SMA-10: a unit is handed back, not held
+        return moved
     return Bi("Stopped — the inverters are set to 0 W",
               "Gestopt — de omvormers staan op 0 W")
 
@@ -601,6 +619,9 @@ def banner_shadow(latched: bool) -> str:
     mode. Each stop has its own red row below, which names it and says how it
     clears.
     """
+    moved = None if latched else handback.banner_shadow(handback.current())
+    if moved is not None:       # SMA-10: a unit is handed back, not held
+        return moved
     if latched:
         return Bi("Shadow mode: battery not controlled. A safety stop stays "
                   "on, see below.",
@@ -1367,6 +1388,8 @@ HINTS = {
     "setup_only": "In setup, nothing is sent to any inverter",
     "roster": "Inverter list read: {n} inverters",
     "maint_history": "Maintenance history did not move over cleanly",
+    "handed_back": "{unit}: handed back, the add-on writes nothing to it",
+    "hand_back_failed": "{unit}: could not be handed back, trying again",
     "stop_restored": "{unit}: an earlier safety stop is back, it stays at 0 W",
     "readings_late": "Home Assistant readings arrive late, control holds",
     "readings_back": "Home Assistant readings are on time again",
@@ -1470,6 +1493,10 @@ def hint(key: str, **kw) -> str:
         kw["w"] = watts(kw["w"])
     if "sw" in kw:
         kw["sw"] = signed_watts(kw["sw"])
+    if key == "shadow_on":      # SMA-10: a unit handed back is not at 0 W
+        moved = handback.hint_shadow_on(handback.current())
+        if moved is not None:
+            return moved
     return HINTS[key].format(**kw)