SAFETY-78: maintenance drain at N=2 no longer stalls

At two inverters the drain pins its pack and the site target is split
around the pin. Below the pin the other pack had to charge, the allocator
refused the opposite directions, and the site sat at 0 W with an ARBITER
line every cycle (house below or above the drain rate, or a grid charge).

main.py now files a site limit `drain` (lo = what the pin places, at
P_MAINTENANCE) at N>=2 while a pack drains, so the other pack only adds
power in the same direction. A drain that cannot give power waits with
one log line. With battery modes on, no grid charge while a pack drains,
and the other battery's card says why. N=1 is byte-identical.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/test_peakguard.py

@@ -2674,9 +2674,15 @@ check("...and so does the persistent notification, which outlives the page and "
 # cycles with the floor, and part 10 at N=1. The sweeps below never reach it:
 # their fixtures leave battery modes off, so they still see {device,
 # supervised, loop}. DECISIONS/OPT-11-battery-modes.md.
+# ⚠️ SAFETY-78 ADDED `drain`, AND IT IS NOT THE DEFERRED RESERVE. It is a
+# site `lo` at P_MAINTENANCE, filed only at N>=2 while a pack's maintenance
+# drain is pinned, equal to what that pin places. It is not conditioned on a
+# state of charge, it never closes discharge (a `lo`, not a `hi`), and it is
+# never filed at N=1, so the sweeps below still see {device, supervised,
+# loop}. DECISIONS/SAFETY-78-drain-at-two.md.
 CLAIM_SOURCES = {"device", "supervised", "failsafe", "safety", "peak",
                  "arbitrage", "maintenance", "loop", "circulation",
-                 "sign_site", "pack", "refused", "mode"}
+                 "sign_site", "pack", "refused", "mode", "drain"}
 # The two appends that file a claim BUILT ELSEWHERE in the method. Named here so
 # that a THIRD such indirection reads as an unrecognised append rather than as a
 # silent gap in the scan.
@@ -2718,7 +2724,7 @@ check("every `claims.append(...)` in main.py's cycle is one this scan can READ "
       "- a claim filed through a shape it cannot parse has to fail here rather "
       "than be counted as nothing, which is how a scan like this goes quietly "
       "vacuous", len(_appends) >= 10 and None not in _filed)
-check("...and the sources that cycle can file are EXACTLY these THIRTEEN. THIS "
+check("...and the sources that cycle can file are EXACTLY these FOURTEEN. THIS "
       "is what makes part 10 a tripwire: replay_loop() hand-builds the claim "
       "list, so it cannot see a claim main.py adds - and a loop-side SoC "
       "reserve is a new source. Filing one takes this line red on the line it "
@@ -2858,7 +2864,7 @@ print("    site: " + ", ".join(sorted(s for s, v in CLAIM_SCOPE.items()
       + "  |  per-inverter: "
       + ", ".join(sorted(s for s, v in CLAIM_SCOPE.items() if v == SCOPE_UNIT)))
 check("...and the split is the one ARB-03 argued, with SAFETY-31's and "
-      "SAFETY-30's and OPT-09's additions: the six about the GRID CONNECTION "
+      "SAFETY-30's, OPT-09's and SAFETY-78's additions: the seven about the GRID CONNECTION "
       "are site claims and the five about a pack, a device or one write are "
       "per-inverter. `circulation` is a site claim because its quantity is "
       "defined over the roster and is identically zero for any one unit; "
@@ -2867,7 +2873,8 @@ check("...and the split is the one ARB-03 argued, with SAFETY-31's and "
       "per-inverter because since SAFETY-30 it grades one unit's command "
       "against that unit's OWN measured power",
       {s for s, v in CLAIM_SCOPE.items() if v == SCOPE_SITE}
-      == {"loop", "peak", "arbitrage", "safety", "circulation", "sign_site"}
+      == {"loop", "peak", "arbitrage", "safety", "circulation", "sign_site",
+          "drain"}
       and {s for s, v in CLAIM_SCOPE.items() if v == SCOPE_UNIT}
       == {"device", "supervised", "failsafe", "maintenance", "pack",
           "refused", "mode"})
@@ -2971,7 +2978,8 @@ check("⚠️ AND THIS IS THE BREAKING HALF. Give the same Controller a second "
                   "mode": "inverter-a",
                   "loop": ACTUATOR_SITE, "peak": ACTUATOR_SITE,
                   "arbitrage": ACTUATOR_SITE, "safety": ACTUATOR_SITE,
-                  "circulation": ACTUATOR_SITE, "sign_site": ACTUATOR_SITE})
+                  "circulation": ACTUATOR_SITE, "sign_site": ACTUATOR_SITE,
+                  "drain": ACTUATOR_SITE})
 check("...and the roster it was restored to is the shipped one, so nothing "
       "below inherits a two-inverter Controller",
       c_src.units == (app_main.UNIT_A,) and len(c_src.inverters) == 1)
@@ -3050,13 +3058,13 @@ _unit_sources_unrouted = [
     if CLAIM_SCOPE.get(r[0]) == SCOPE_UNIT and "," not in r[1]]
 print(f"    {len(_direct)} direct appends, each read at its own line: "
       + ", ".join(f"main.py:{ln} {s} -> {a}" for s, a, ln in _routing))
-check("all FOURTEEN of `Controller.cycle()`'s DIRECT appends route through "
+check("all FIFTEEN of `Controller.cycle()`'s DIRECT appends route through "
       "`self.actuator_of(<string literal>)`, so this scan can read the routing "
       "of EVERY one of them. An append that computed its actuator, or omitted "
       "the argument, or hand-wrote a string, fails HERE rather than being "
       "silently skipped - which is how a scan like this goes quietly vacuous, "
       "and 10f is in this file because that already happened once",
-      len(_direct) == 14
+      len(_direct) == 15
       and all(a is not None and a.startswith("self.actuator_of('")
               for _s, a, _ln in _routing))
 check("⚠️ AND AT EVERY ONE OF THE ELEVEN THE LITERAL IT ROUTES THROUGH IS THE "
@@ -3073,7 +3081,7 @@ check("⚠️ AND EVERY PER-INVERTER APPEND NAMES THE INVERTER IT IS ABOUT. "
       "site-scoped sources and is the whole defect for a per-inverter one: a "
       "`device` limit built inside the roster loop and routed without `inv` "
       "files inverter B's rating on inverter A, where it binds the wrong "
-      "share. Nine of the fourteen appends are SCOPE_UNIT - `device`, "
+      "share. Nine of the fifteen appends are SCOPE_UNIT - `device`, "
       "`supervised`, `failsafe`, maintenance's two, OPT-09's `pack`, "
       "SAFETY-73's two `refused` and OPT-11's `mode` - and all nine pass one. "
       "SAFETY-30's `sign_site` is deliberately NOT one of them: it is filed on "
@@ -3090,8 +3098,8 @@ check("...and the only appends this pin does NOT reach are the two that file a "
       "arbitrage.claim() by test_arbitrage.py",
       sorted(_indirect) == sorted(CLAIM_BUILDERS)
       and len(_direct) + len(_indirect) == len(_appends))
-check("...and between them the sixteen appends account for exactly the "
-      "thirteen "
+check("...and between them the seventeen appends account for exactly the "
+      "fourteen "
       "sources 10f pins, so the routing pin and the source set are one scan "
       "and neither can drift from the other",
       {s for s, _a, _ln in _routing} | set(CLAIM_BUILDERS.values())
@@ -3152,7 +3160,7 @@ check("...and naming those three is not an accident of this fixture but the "
       {c.source for c in _cl2}
       == CLAIM_SOURCES - {"failsafe", "safety", "maintenance", "peak",
                           "arbitrage", "circulation", "sign_site",
-                          "refused", "mode"})
+                          "refused", "mode", "drain"})
 # ⚠️ AND NOW THE HALF THAT WAS EVIDENCE-SHAPED AND OBSERVED NOTHING. The three
 # checks above grade WHICH ACTUATOR each claim lands on. They say nothing about
 # WHOSE NUMBERS the bound is built from - and those are two different defects