SAFETY-32: bms_soc_floor per pack, rule 8 per unit

`bms_soc_floor` describes A BATTERY, not a site. At two packs of different
models the cut-outs differ, and one number for both graded the shallower pack
against the deeper one's BMS - so a site with cut-outs of 10 % and 30 % under
`peak_soc_floor: 20` STARTED, and the guard would command a forced discharge
that pack B's BMS, not the operator's floor, is the thing that stops. That is
rule 8's own failure mode, reached through rule 8.

Scoped to the card's third bullet, per its PM PROOFREAD: the aggregate
anti-windup (DEV-02) and per-instance `achievable_w` (CFG-04) were verified as
already shipped and are untouched.

* config.yaml: `bms_soc_floor: int(0,50)` REQUIRED per `inverters:` entry.
  Nothing is inherited; the flat key stays the single-inverter shape's own
  cut-out. A per-entry DEFAULT was declined - a default is one number for every
  pack, which is this card's defect - and the decision is recorded.
* inverter.py: `Inverter.bms_soc_floor`; an entry that states none gets None,
  not a borrowed number and not 0.0 (the most permissive value the key has).
* peakguard.py: `Pack`, `pack_floor_pct()`, `pack_permissions()`,
  `binding_soc_floor()`. `discharge_permitted()` is unchanged and is still the
  one place the question is answered.
* validate.py: `unit_bms_floors_indexed()` carries the ROSTER index; rule 8
  grades EVERY unit and NAMES the one it refuses. Graded with the offender
  SECOND and with the same two numbers in the other order.
* main.py: `Controller.packs`; `decide(soc_floor=...)` is the per-pack
  reduction of the same option; the floor-limited notification names the pack
  that stopped the site. `pack_floor_soc` - the emptiest pack, and its
  None-on-missing behaviour - is untouched.
* tools/supervisor_shape_probe.py: RE-RUN and repaired. The required key broke
  §C and left §D printing PASS on a refusal about a different key. §D is now an
  isolated counterfactual over an accepted merged baseline, one key varied,
  asserting the key name. `all cases passed` on 2026.08.0.

Stated rather than hidden: under any config rule 8 accepts the per-pack FLOOR
reduces to `peak_soc_floor` for every pack. The reduction is written for
`unit_caps_indexed()`'s reason and graded on both sides - 1775 rule-8-valid
pairs answer the option, the pair rule 8 refuses answers the cut-out.
`peak_soc_floor` is still one number for the site, so the "deeper pack
needlessly withheld" half is filed as an open question, not closed.

Full 19-file suite green. Twelve source mutations through
tools/mutation_run.sh: eleven red, one argued survivor. The battery also found
`_flat_bms_floor()` defaulting in two places, each covering for the other.

No measurement of inverter B appears anywhere: it does not exist yet. Every
second-pack figure is simulated and labelled.

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

goodwe_controller/config.yaml

@@ -56,23 +56,41 @@ options:
   #       soc_entity: sensor.goodwe_a_soc
   #       batt_entity: sensor.goodwe_a_battery_power
   #       max_w: 5000
+  #       bms_soc_floor: 10
   #     - name: inverter-b
   #       setpoint_entity: number.goodwe_b_setpoint_w
   #       soc_entity: sensor.goodwe_b_soc
   #       batt_entity: sensor.goodwe_b_battery_power
   #       max_w: 3000
+  #       bms_soc_floor: 10
+  #
+  # ⚠️ THE SECOND ENTRY ABOVE IS AN EXAMPLE, NOT A MEASUREMENT. No second
+  # inverter exists on this site yet; its 3000 W rating and its 10 % cut-out are
+  # placeholders in a comment, and the cut-out in particular must be read off the
+  # pack that is actually installed (register 0x0560 on the reference unit)
+  # before that pack is commanded.
   #
   # ⚠️ NOTHING IS INHERITED FROM THE FLAT KEYS BY AN ENTRY THAT OMITS IT, and
   # that is the whole of DEV-02 restated as a config rule. `soc`, `batt` and the
   # rating became per-instance precisely so that no inverter is ever graded
   # against a sibling's numbers; an entry silently inheriting `soc_entity` would
-  # rebuild that defect in YAML. `name`, `setpoint_entity` and `max_w` are
-  # therefore REQUIRED of every entry (the schema below enforces it, and
+  # rebuild that defect in YAML. `name`, `setpoint_entity`, `max_w` and
+  # `bms_soc_floor` are therefore REQUIRED of every entry (the schema below enforces it, and
   # validate.py rule 9 enforces it again for the callers the Supervisor never
   # sees). An omitted `soc_entity`/`batt_entity` means THIS UNIT HAS NO SUCH
   # SENSOR - `inputs_ok` already stops the site for that - and never means
   # "use the other one's".
   #
+  # ⚠️ SAFETY-32: `bms_soc_floor` IS PER ENTRY AND IS REQUIRED, NOT DEFAULTED.
+  # It is the percent THAT pack's own BMS cuts out at, and two batteries of
+  # different models do not share one. A default would be this add-on inventing
+  # a cut-out for a battery it has not been told about, which is the same defect
+  # as inheriting one: the shallower pack gets protected by a floor that belongs
+  # to the deeper pack, and validate.py rule 8 - which refuses a peak_soc_floor
+  # the BMS would win against - would be grading the wrong number. Rule 8 grades
+  # EVERY entry and names the one it refuses. The flat key below is unchanged and
+  # is the single-inverter shape's own cut-out.
+  #
   # ⚠️ AND THE FLAT `setpoint_entity` MUST THEN BE BLANK. Leaving it set while a
   # roster is declared is two config sites aimed at actuators, one of which
   # nothing writes; if it names an entity an entry also names, SAFETY-28's
@@ -355,6 +373,13 @@ options:
   # DoD 90. It is here so validate.py can REFUSE a peak_soc_floor at or below
   # it: such a floor can never bind, the BMS wins, and the status page would
   # report an energy backstop that does not exist.
+  #
+  # ⚠️ SAFETY-32 - THIS KEY DESCRIBES ONE PACK, so it is the SINGLE-INVERTER
+  # shape's number and nothing more. Declare an `inverters:` roster and each
+  # entry states its own `bms_soc_floor`; this one is not read at all and is
+  # not inherited by any entry. Rule 8 then grades every unit separately, which
+  # is the whole of that card: one cut-out for two packs of different models
+  # protects the shallower pack with the deeper pack's number.
   bms_soc_floor: 10
 
   # ⚠️ THE OLD PRICE PATH, AND IT IS NOT DEAD YET. These two entities are the
@@ -500,6 +525,7 @@ schema:
     - name: str
       setpoint_entity: str
       max_w: int(100,5000)
+      bms_soc_floor: int(0,50)
       soc_entity: str?
       batt_entity: str?
       batt_invert: bool?