OPT-09: the weights parameter nothing ever passed, and what it cannot do

`allocator.plan()` has taken a `weights` argument since ALLOC-01 and NOTHING
had ever passed one - main.py called `resolve()` without it and the arbiter
defaulted it to 1.0 per unit - so the site target was split 50/50 regardless
of what either pack could do. Two things now feed it, and they are different
kinds of thing:

  * a `pack` UNIT claim at P_SAFETY that CLOSES a unit's envelope at its own
    `bms_soc_floor` or at 100 % - a PERMISSION, obeyed absolutely, so an empty
    pack is not asked to discharge and its share goes to the sibling;
  * SoC-aware weights by ENERGY headroom in kWh - a PREFERENCE, which
    `_fill()`'s last-resort pass will override the moment the sibling saturates.

Measured (test_packshare.py part 8): at a load one pack cannot cover, the
weighted arm and the shipped arm command the IDENTICAL watts into an empty pack
and deliver the IDENTICAL watts. Only the envelope stops the ask, and what it
buys is not delivery - it is a reported `unmet_w` where the record used to read
impeccable. Weights are a comfort choice for STABILITY and NOT for DELIVERY.

Also: an optional per-entry `capacity_kwh` (schema change, all-or-nothing across
the roster, rule 9 refuses a partial one); per-pack arbitrage sizing, with the
sell side's no-op stated rather than hidden; and a 0 W trade refused by name,
because a 0 W arbitrage claim is a park order that outranks the loop.

SAFETY-42 and this card meet at one hazard from opposite sides - OPT-09 stops
the site ASKING a pack whose SoC says it cannot deliver, SAFETY-42 alarms when a
pack that said it could does not - and its end-to-end fixture moved as a result.
Its finding is unchanged and is now stated on the two quantities its rejected
discriminator actually reads.

Not filed at all at a roster of one: at N=1 every source routes to the site, so
the interval would bound the SITE TARGET, and SAFETY-25's decided Option A
stands untouched on the live install.

⚠️ INVERTER B DOES NOT EXIST. Its 4600 W / 20.48 kWh / 10 % are FROM DATASHEET
AND SERIAL, and `sim/plantsim.py`'s INVERTER_B is inverter A copied
(`measured=False`), so every two-inverter figure here is arithmetic or two
copies of A. No hardware was touched.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU

goodwe_controller/app/arbiter.py

@@ -205,6 +205,27 @@ CLAIM_SCOPE = {
     # At N=1 the two are the same comparison and this claim is the one filed,
     # exactly as it shipped.
     "failsafe": SCOPE_UNIT,
+    # main.py: `Claim.limit("pack", P_SAFETY, lo, hi, ...)`, OPT-09. THIS PACK'S
+    # OWN STATE OF CHARGE against THIS PACK'S OWN `bms_soc_floor`, filed only
+    # where it BINDS and only at a roster of two or more. It says "this battery
+    # cannot do that", which is a fact about one cupboard in the same way
+    # `device`'s rating is a fact about one box, so it is scoped like `device`
+    # and filed at the same priority.
+    #
+    # ⚠️ AND IT IS NOT SAFETY-25's DEFERRED LOOP-SIDE RESERVE, WHICH LOOKS
+    # EXACTLY LIKE IT AND IS THE REASON test_peakguard.py PART 10f EXISTS. That
+    # one was `Claim.limit("reserve", P_LOOP, hi=0.0)` under a NEW
+    # `loop_soc_floor` option - an EMS preference, chosen by an operator,
+    # stopping the grid-following loop at a depth somebody picked. This is the
+    # pack's own BMS cut-out, which is measured off register 0x0560 and required
+    # of every roster entry since SAFETY-32; no option is added, `peak_soc_floor`
+    # is deliberately NOT consulted, and the SITE target is not touched - only
+    # which unit carries it. Part 10f's own note names the revisit trigger:
+    # "under ALLOC-01 the reserve becomes a PER-INVERTER INTERVAL AT THE
+    # ALLOCATOR rather than a ninth claim here", and stage 1 is how an interval
+    # reaches the allocator, so a unit-scoped claim is the shape that sentence
+    # asks for rather than an evasion of it.
+    "pack": SCOPE_UNIT,
     # main.py: `Claim.set("maintenance", P_MAINTENANCE, ...)` when the cycle owns
     # the setpoint, and `Claim.limit("maintenance", P_MAINT_SHAPE, hi=...)` when
     # it only shapes. §12's monthly recalibration is a PACK procedure - drain
@@ -544,7 +565,10 @@ def resolve(claims: list, *, units=None, weights=None, live=None,
 
     `weights` and `live` are ALLOC-01's two per-tick inputs to stage 3, and both
     are per-TICK on purpose. `weights` is the comfort choice - SoC, thermals,
-    wear - and cannot destabilise the site whatever it says. `live` is the set
+    wear - and cannot destabilise the site whatever it says. ⚠️ OPT-09 LET IT BE
+    A CALLABLE as well as a mapping: called with the resolved site target once
+    stage 2 has run, because an energy-headroom weighting is direction-dependent
+    and the direction is stage 2's answer. See the call site below. `live` is the set
     of units whose master has reported recently enough to be commanded; a unit
     left out of it is DROPPED from the envelope set and the record says so,
     because the survivor carrying a dead unit's share silently is the failure
@@ -600,6 +624,27 @@ def resolve(claims: list, *, units=None, weights=None, live=None,
     # left as a log line nothing grades.
     out.scope_errors = scope_violations(claims)
     out.unit_bounds = bounds
+    # OPT-09. THE WEIGHTS MAY ARRIVE AS A FUNCTION OF THE SITE TARGET, and this
+    # is the one line that makes SoC-aware weighting expressible at all.
+    #
+    # ⚠️ THE REASON IS THAT THE DIRECTION IS NOT KNOWN ANY EARLIER. A weighting
+    # by ENERGY HEADROOM is direction-dependent - room above the floor when the
+    # site is discharging, room below full when it is charging - and the two
+    # give opposite answers on the same roster. The site target is chosen by
+    # stage 2, three lines up, so a caller computing weights before `resolve()`
+    # would have to guess which way the site is about to go, and would be wrong
+    # in one of the two directions on every tick.
+    #
+    # ⚠️ IT IS CALLED ONCE, HERE, BETWEEN STAGE 2 AND STAGE 3, AND NEVER FROM
+    # INSIDE THE ALLOCATOR. `allocator.plan()` goes on taking a plain mapping,
+    # which is what keeps it a pure function of numbers and intervals: a
+    # callback invoked inside the fill would put a caller's code - and whatever
+    # it reads - back into the module whose whole discipline is that it reads
+    # nothing. See `packshare.weights()` on the residual this leaves (the fill's
+    # own direction can differ from the target's sign under a pin, in which case
+    # the weighting is a worse preference and still cannot be unsafe).
+    if callable(weights):
+        weights = weights(out.target_w)
     out.shares, out.allocated, out.allocation = allocate_record(
         out.target_w, bounds, weights=weights, live=live,
         scope_errors=out.scope_errors, site_priority=out.winner_priority,