SAFETY-31 AC 4: the alarm's attribution was graded by nothing, and a mutation proved it

`pos, neg = opposing(...)` -> `([], [])` in main.py's `check_circulating()`
(-102 B) deletes the "Right now X is discharging while Y charges" clause from
the operator notification, and SURVIVED ALL 26 FILES. The commit that shipped
this card claimed "18 mutations, all RED"; the ledger has no entry for the
attribution, and this is that entry.

It is not dead code. Ledger M18 - the whole `await check_circulating()` call
removed - is red on four checks, so the function runs. The three checks on the
notification asserted METER CANNOT SEE, CONTROL HAS BEEN STOPPED and `isolator`,
and never an inverter name. `circulation.py`'s own docstring calls that sentence
the first thing somebody woken by this alarm needs and "impossible to
reconstruct from the number alone".

test_watchdog.py section 6a closes it on a fixture that can tell three failures
apart:

  * the roster is ["garage", "shed", "cellar"] - operator names, none of them
    `UNIT_A`, for test_maintenance.py section 11's reason: on a fixture whose
    names are the module's own constants a check cannot tell the roster from
    the constant;
  * the site is run TWICE, MIRRORED, so the sentence is not symmetric and a
    pos/neg swap is a different red from a deletion;
  * a third pack rests at 5 W, so the floor that stops a pack in standby being
    named as a participant in a 6 kW loop is graded too.

Mutations, on a tree with no __pycache__ mounted :ro into the checks image:

  M20  pos, neg = opposing(...) -> ([], [])          -102 B  RED (2 checks)
  M21  pos and neg exchanged                          +0 B   RED (3 checks)
  M22  opposing(..., min_w=cfg.min_w/2.0) -> 0.0      -25 B  RED (3 checks)

26/26 files green with the block in place.

AND A DISCLOSURE, WHICH IS THE UNCOMFORTABLE HALF. DECISIONS section 3 records
that the 924-run campaign behind `circulation_w: 700` and `circulation_hold_s:
75` used a harness that is not committed in either repository. Two further
sweeps have now been run and no two of the three agree: peaks of 1700 W, 2750 W
and 1048 W, and worst-continuous figures above 700 W of 5.0 s, 15.0 s and 5.0 s.

That is NOT evidence of fabrication and is not reported as any. The committed
sweep measures why the spread is that wide: on one grid, changing only the
plant model and the write-stagger set, the worst legitimate peak is 1048 W, or
2250 W, or 0 W. The plant and the stagger are TERMS of the number. What the
spread does establish is that the claim cannot be adjudicated while the
instrument is missing.

The window argument survives and is now committed - all three sweeps trip zero
times, on 924 + 48 + 840 non-faulty runs. The threshold CURVE does not survive
as stated: `505.0 s at 100 W`, which is what the "knee at 400 W" argument rests
on, is 10.0 s on the committed grid. The curve still falls with the threshold,
so the knee is real in direction; its depth is established by nothing anybody
can run, and this commit says so rather than repeating it. The overclaiming
comment at test_watchdog.py's 1700 W fixture ("the worst single transient the
rig can produce") is replaced with what the fixture can support.

The committed, re-runnable half is admin/goodwe's `two_master_circulation`,
opened as a separate PR against that repository.

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

goodwe_controller/DECISIONS/SAFETY-31-circulating-power.md

@@ -149,8 +149,70 @@ each swept across the **whole range `config.yaml` accepts** for the two settings
 that decide how fast the site can turn around: `gain` `float(0.05,1.0)` and
 `slew_w` `int(50,5000)`.
 
+### ⚠️ THE HARNESS BEHIND EVERY FIGURE ABOVE IS NOT COMMITTED, AND UNTIL 2026-09-07 THAT MADE THEM UNCHECKABLE
+
+**Read this before quoting any number in this section.** The paragraph below
+said the campaign harness "is not committed here" and treated that as a
+packaging detail. It is not: a figure produced by a script that exists in
+nobody's tree cannot be re-run, cannot be reviewed, and cannot be defended when
+it is contradicted. It has now been contradicted twice.
+
+| sweep | worst peak | worst continuous | trips |
+|---|---:|---:|---:|
+| the 924-run campaign below — **harness uncommitted** | 1700 W | 505.0 s at 100 W; 5.0 s above 700 W | 0 / 924 |
+| independent reviewer sweep, 2026-09-07, 48 honest reversals | **2750 W** | **15.0 s above 700 W** | 0 / 48 |
+| `admin/goodwe` `two_master_circulation`, 840 runs — **committed** | 1048 W | 10.0 s at 100 W; 5.0 s above 700 W | **0 / 840** |
+
+**This is not proof that anything was fabricated, and it should not be reported
+as one.** The three swept different grids. What the third one adds is a
+measurement of *why* the spread is that wide — on one grid, changing nothing but
+the model:
+
+| plant / stagger | worst legitimate peak |
+|---|---:|
+| modelled plant (lag 10 s, ramp 800 W/s), staggers up to a whole cycle | 1048 W |
+| `INSTANT` (lag 0, unbounded ramp), staggers up to a whole cycle | 2250 W |
+| `INSTANT`, staggers strictly under a whole cycle | **0 W** |
+
+A factor of 2.1×, and a factor of infinity, between three defensible
+descriptions of the same rig. **The plant model and the write-stagger set are
+terms of the number**, and a worst case quoted without them is not a
+measurement. That is enough to explain the whole spread above without anybody
+having invented anything — and it is exactly what cannot be established when the
+instrument is missing.
+
+**What survives, and what does not.**
+
+* **The window argument survives, and is now committed.** The claim that
+  decides `circulation_hold_s: 75` is *"the worst continuous legitimate episode
+  above 700 W is about one control cycle"*. All three sweeps agree on the shape
+  of that (5.0 s, 15.0 s, 5.0 s — one to three cycles against a fifteen-cycle
+  window), and **all three trip zero times**. `two_master_circulation` re-runs
+  it on every pull request in `admin/goodwe`.
+* **The threshold curve does NOT survive as stated.** `505.0 s at 100 W` is the
+  number the "knee at 400 W" argument for `circulation_w: 700` rests on, and the
+  committed sweep measures **10.0 s** at 100 W on its grid — 50× smaller. The
+  curve still *falls* with the threshold (126 of 840 runs cross 100 W against 1
+  that crosses 700 W), so the knee is real in direction; its depth is not
+  established by anything anybody can run. **Do not quote 505.0 s.**
+* **Nothing about the guard is compromised.** 0 trips in 924 + 48 + 840
+  non-faulty runs, from three independent grids.
+
+**What would settle it:** the original harness, committed. Until then the
+committed sweep is the only figure in this section anybody can check, and it is
+labelled as its own grid's rather than as a reproduction.
+
 ### Reproducing it
 
+⚠️ **THE COMMITTED VERSION IS `admin/goodwe`'s `sim/inject.py
+two_master_circulation`** (`sim/sitesim.py:circulation_findings`, runnable on its
+own as `python3 sim/sitesim.py --circulation`, `norig`, ~36 s, graded by
+`checks.yml` on every pull request there). It produces the fault with
+`plantsim.Inverter.wedge()` — a unit answering its bus and no longer steering its
+power stage, which is HW-01 — and sweeps the legitimate family with the
+serialised write path staggered up to a whole control cycle. The paragraph below
+describes the ORIGINAL campaign, which is the one that is not committed.
+
 The rig lives in `admin/goodwe` (`sim/`) and was used **read-only**; the harness
 is not committed here because it imports that repo's `plantsim`/`frame_check`,
 which are not present in this one or in CI. What it does is small enough to
@@ -206,7 +268,11 @@ margin above the knee is what absorbs that without re-opening this card.
 **Revisit when SPIKE-04 lands, not before.**
 
 The **schema floor is the knee itself**, 400 W, so a legally configured install
-cannot land in the 445–505 s regime. What the threshold costs: a circulating
+cannot land in the 445–505 s regime — ⚠️ and those two figures are from the
+uncommitted campaign; the committed sweep measures 10.0 s at 100 W on its own
+grid. See the disclosure at the head of this section. The floor is still the
+right shape (fewer runs cross a higher threshold, measured 126/840 at 100 W
+against 1/840 at 700 W); its DEPTH is not established by anything re-runnable. What the threshold costs: a circulating
 loop smaller than 350 W per unit is not reported, which is deliberate — at that
 scale the round-trip loss is a few watts.
 
@@ -289,7 +355,32 @@ SAFETY-25 — so no stale `.pyc` could exist to be read. Byte deltas recorded;
 | M17 | `circulation.py` | default `700` → `500` | **+0 B** | **RED** — the CFG-03 pin and the not-a-round-number check |
 | M18 | `main.py` | `await self.check_circulating()` removed | −39 B | **RED** — all four notification checks |
 | M19 | `main.py` | publish `round(x or 0.0)` instead of `None` | −68 B | **survivor on the first battery — GAP CLOSED**, then RED |
+| **M20** | `main.py` | **`pos, neg = opposing(...)` → `([], [])`** — the attribution clause deleted from the alarm | −102 B | **SURVIVED ALL 26 FILES on the shipped battery — GAP CLOSED**, then RED on §6a |
+| M21 | `main.py` | `pos` and `neg` exchanged — the alarm names both packs, both the wrong way round | **+0 B** | **RED** — §6a ×3 (the mirrored run, and "only its own sentence") |
+| M22 | `main.py` | `opposing(..., min_w=cfg.min_w / 2.0)` → `min_w=0.0` | −25 B | **RED** — §6a's resting-pack check |
 
+**And four in `admin/goodwe`**, graded through `python3 sim/sitesim.py
+--circulation` rather than through the injector — deliberately, because
+`inject.py` is the file that takes the rig lock, and "run the injector to grade a
+mutation" is not a sentence anybody should have to type. Byte deltas over
+`plantsim.py` + `sitesim.py` together.
+
+| # | file | mutation | Δ | result |
+|---|---|---|---|---|
+| S1 | `plantsim.py` | `wedge()` no longer stops the latch reaching the power stage | −20 B | **RED** — the opposing-signs precondition **and** "the watchdog did not trip" |
+| S2 | `sitesim.py` | the sensor computed over the **allocation record** instead of register 0x0518 | **+0 B** | **RED** ×3 — this is M10 restated on the rig |
+| S3 | `sitesim.py` | the campaign run on `plant=INSTANT` | −51 B | **RED** — the plant is a *term* of the figures; it was a SURVIVOR until that check was added, and finding out why produced §3's 1048/2250/0 W table |
+| S4 | `sitesim.py` | the write stagger removed from the legitimate campaign | −19 B | **RED** — "the legitimate campaign produced no opposition at all" |
+
+**S3 is recorded as a survivor because it was one, and it is the most useful
+result in this table.** The scenario first shipped with a vacuity check whose
+text claimed `plant=INSTANT` would make the sweep measure 0 W. S3 was run and
+**passed**: `INSTANT` with a stagger of exactly one control cycle samples the
+plant before the second unit has stepped, so it produces opposition anyway — and
+a *larger* worst peak (2250 W) than the modelled plant does (1048 W). The claim
+in the check's own text was wrong. It was corrected against the measurement, the
+plant was pinned as an explicit term, and S3 is red now for a stated reason
+rather than by accident. §3's spread table is that measurement.
 **M19 is recorded as a survivor because it was one.** The first battery found no
 check grading what `publish()` does when a per-unit reading is missing, so
 turning *"I do not know"* into *"0 W"* on the one surface an operator actually
@@ -297,6 +388,30 @@ watches went unnoticed — the sensor's own `None` rule, defeated one layer out.
 A check was added and the mutation re-run; it is red now. The run that found it
 was purged, so it is a result and not an artefact.
 
+**M20 IS RECORDED AS A SURVIVOR BECAUSE IT WAS ONE, AND IT IS THE MORE
+UNCOMFORTABLE OF THE TWO.** The commit message for this card claimed *"18
+mutations, all RED"*, and M1–M19 above have no entry for the notification's
+attribution clause. Verification on 2026-09-07 ran it and it **survived the
+whole 26-file suite**: the alarm still fires, still stops the site, still says
+the meter cannot see it — and no longer says *which two packs* or *which way
+round*. `circulation.py`'s own docstring calls that sentence the first thing
+somebody woken by this alarm needs and *"impossible to reconstruct from the
+number alone"*.
+
+It survived for one reason, and it is not reachability: **M18 (the whole call
+removed) is red**, so `check_circulating()` is exercised. The three checks on
+that notification asserted `METER CANNOT SEE`, `CONTROL HAS BEEN STOPPED` and
+`isolator` — and **never an inverter name**. Nothing graded the attribution.
+
+`test_watchdog.py` §6a closes it, and closes it on a fixture that can tell the
+three failures apart. It runs a roster of **`["garage", "shed", "cellar"]`** —
+operator names, none of them `UNIT_A`, for test_maintenance.py §11's reason:
+on a fixture whose names are the module's own constants a check cannot tell the
+roster from the constant. It runs the site **twice, mirrored**, so the sentence
+is not symmetric and a swap (M21, `+0 B`) is a different red from a deletion.
+And it carries a **third pack resting at 5 W**, so the floor that stops a pack
+in standby being named as a participant in a 6 kW loop (M22) is graded too.
+
 ## 7. What this card does NOT close
 
 * **Inverter B's ramp and lag are placeholders.** Every transient number in §3
@@ -305,7 +420,9 @@ was purged, so it is a result and not an artefact.
   margin. **Do not present any figure here as a measurement of inverter B.**
 * **A wedged inverter still cannot be stopped by this add-on.** §1 says so; the
   notification says so; there is no software fix and this card does not pretend
-  to one.
+  to one. It *can* now be produced on demand: `plantsim.Inverter.wedge()`.
+* **The depth of the threshold curve is not established by anything committed.**
+  §3's disclosure. The window is; the knee's magnitude is not.
 * **A loop below ~350 W per unit is not reported.** Deliberate, §3.
 * **The saturation freeze fires under a wedged unit and leaves a standing grid
   error.** Observed on the rig while producing §2's numbers: with B wedged, the

goodwe_controller/test_watchdog.py

@@ -722,18 +722,41 @@ print(f"       e.g. {_sustained.reason!r}")
 
 print()
 print("   ⚠️ AND NOT ON THE TRANSIENT, WHICH IS THE FALSE-ALARM CASE")
-# ⚠️ THE SHAPES BELOW ARE THE RIG'S, NOT INVENTED. Measured on TEST-19 over 924
-# closed-loop runs in which every unit executed the share it was given: the
-# worst continuous opposition above 700 W is 5.0 s - ONE control cycle - at a
-# peak of 1700 W. That is the serialised write path: on a reversing cycle B's
-# new number lands up to a whole cycle after A's, both slew through zero at
-# 800 W/s behind a 10 s lag, and between the two crossings they genuinely
-# oppose. A guard that trips on that is a false-alarm generator, and this
-# project's doctrine on crying wolf is explicit (SAFETY-15, SAFETY-19).
+# THE SHAPE BELOW IS THE RIG'S: the serialised write path means that on a
+# reversing cycle B's new number lands up to a whole control cycle after A's,
+# both slew through zero behind a real ramp and a real lag, and between the two
+# crossings they genuinely oppose. A guard that trips on that is a false-alarm
+# generator, and this project's doctrine on crying wolf is explicit (SAFETY-15,
+# SAFETY-19).
+#
+# ⚠️ THE MAGNITUDE IS A FIXTURE INPUT, NOT A MEASUREMENT, AND THIS COMMENT USED
+# TO SAY OTHERWISE. It read "the worst single transient the rig can produce -
+# 1700 W", sourced to a 924-run campaign whose harness IS NOT COMMITTED IN
+# EITHER REPOSITORY (DECISIONS/SAFETY-31-circulating-power.md §3 says so in its
+# own words). Three sweeps have now been run against that claim and no two agree:
+#
+#     924-run campaign, harness uncommitted     peak 1700 W, 505.0 s at 100 W
+#     independent reviewer sweep, 2026-09-07    peak 2750 W,  15.0 s above 700 W
+#     goodwe `two_master_circulation`, 840 runs peak 1048 W,   5.0 s above 700 W
+#
+# ⚠️ THAT IS NOT EVIDENCE THAT ANY OF THEM IS WRONG. The three swept different
+# grids, and the last one measured WHY the spread is so wide: on its own grid the
+# worst legitimate peak is 1048 W on the modelled plant, 2250 W on `INSTANT`, and
+# 0 W on `INSTANT` with no write stagger reaching a whole cycle. The plant model
+# and the stagger set are TERMS of the number, and a worst case quoted without
+# them is not a measurement. It is evidence that the claim cannot be adjudicated
+# while the instrument is missing.
+#
+# So what this check now says is what it can support: 1700 W is LARGER than
+# anything any of the three sweeps produced legitimately, and one control cycle
+# of it does not trip. The committed, re-runnable version of the claim is
+# `admin/goodwe`'s `sim/inject.py two_master_circulation`, which runs on every
+# pull request there and requires ZERO of ~840 non-faulty runs to trip.
 _one_cycle = [0.0] * 5 + [1700.0] + [0.0] * 30
 _t1, _ = circ_drive(_one_cycle)
-check("the worst single transient the rig can produce - 1700 W for ONE control "
-      "cycle - does not trip", not _t1.tripped)
+check("a single transient of 1700 W - larger than the worst peak any committed "
+      "sweep of the legitimate family has produced - lasting ONE control cycle "
+      "does not trip", not _t1.tripped)
 _repeated = ([0.0] * 3 + [1700.0]) * 20
 _t2, _ = circ_drive(_repeated)
 check("...and neither does it REPEATED every fourth cycle for 400 s, which is "
@@ -1091,6 +1114,158 @@ check("...and it does not raise the same card on every cycle - a per-PROCESS "
       "this' a different question from 'is this site tripped'",
       len(_notes2) == 1)
 
+
+print()
+print("6a. AC 4: THE ALARM NAMES WHICH PACKS, AND WHICH WAY ROUND")
+# ⚠️ THIS BLOCK EXISTS BECAUSE A MUTATION SURVIVED ALL 26 FILES. Replacing
+#
+#     pos, neg = opposing([inv.batt for inv in self.inverters],
+#                         min_w=self.circ_wd.cfg.min_w / 2.0)
+#
+# in `check_circulating()` with `pos, neg = ([], [])` (-102 B) silently deletes
+# the "Right now X is discharging while Y charges" clause from the notification,
+# and the whole suite stayed GREEN. The block above asserts three tokens -
+# METER CANNOT SEE, CONTROL HAS BEEN STOPPED, isolator - and NEVER an inverter
+# name, so the one sentence `circulation.py` calls "the first thing somebody
+# woken by this alarm needs" and "impossible to reconstruct from the number
+# alone" was graded by nothing at all.
+#
+# ⚠️ IT IS NOT DEAD CODE, WHICH IS THE PART THAT MAKES IT A CHECK GAP RATHER
+# THAN A REACHABILITY ONE. Ledger M18 - the `await self.check_circulating()`
+# call removed - goes red on four checks above, so this function runs. What
+# nothing asserted was the ATTRIBUTION.
+#
+# ⚠️ AND THE ROSTER IS ["garage", "shed", "cellar"], WHICH IS THE OTHER HALF OF
+# THE FIX. Every fixture above runs on `inverter-a`/`inverter-b`;
+# test_maintenance.py section 11 records what that costs - on a fixture whose
+# names are the module's own constants, a check cannot tell the roster from the
+# constant, and `UNIT_A` is not even what a nameless entry falls back to. Here
+# the names are an operator's, the two participants pull OPPOSITE ways so the
+# sentence is not symmetric, and a third pack rests at 5 W. That makes three
+# DIFFERENT mutations - the clause dropped, the two directions swapped, and the
+# `min_w` floor dropped - into three DIFFERENT red checks. A fixture naming both
+# units the same, or one in which the direction did not matter, would see the
+# first and neither of the others.
+
+_CIRC_ROSTER = [
+    dict(name="garage", setpoint_entity="number.sp_a", soc_entity="sensor.soc_a",
+         batt_entity="sensor.batt_a", max_w=5000),
+    # ⚠️ B_RATING_HYPOTHESIS, and part 4's note above says why it is not 4600:
+    # inverter B does not physically exist and a datasheet is not a measurement.
+    dict(name="shed", setpoint_entity="number.sp_b", soc_entity="sensor.soc_b",
+         batt_entity="sensor.batt_b", max_w=B_RATING_HYPOTHESIS),
+    # THE BYSTANDER. A third pack resting at standby draw, on the roster, read
+    # every cycle, and NOT a participant in anybody's loop.
+    dict(name="cellar", setpoint_entity="number.sp_c", soc_entity="sensor.soc_c",
+         batt_entity="sensor.batt_c", max_w=B_RATING_HYPOTHESIS),
+]
+_CIRC_NAMES = [e["name"] for e in _CIRC_ROSTER]
+_REST_W = 5.0
+
+
+class _NamedCircHass(_Hass):
+    """Three named packs; the meter still reads exactly zero.
+
+    Same house as `_CircHass` - grid = load - sum(B) with two units cancelling -
+    with one extra pack idling at standby draw so that "who is named" and "who
+    is merely on the roster" are different questions.
+    """
+
+    def __init__(self, a_w, b_w, c_w=_REST_W):
+        super().__init__()
+        self.vals = {"sensor.batt_a": a_w, "sensor.batt_b": b_w,
+                     "sensor.batt_c": c_w}
+
+    async def number(self, entity, invert=False):
+        return {"sensor.grid": 0.0, "sensor.soc_a": 50.0,
+                "sensor.soc_b": 50.0, "sensor.soc_c": 50.0,
+                **self.vals}.get(entity)
+
+
+def _named_trio(hass, store, *, hold_s=1, min_w=700):
+    opts = {"meter_entity": "sensor.grid", "meter_source": "off",
+            "max_w": 5000, "gain": 0.6, "auto_start": True,
+            "circulation_w": min_w, "circulation_hold_s": hold_s,
+            "inverters": _CIRC_ROSTER}
+    c = Controller(opts, hass, store, _P(), stop=asyncio.Event())
+    c.auto = True
+    for inv in c.inverters:
+        inv.dev_min, inv.dev_max = -5000.0, 5000.0
+    return c
+
+
+async def _circ_named(a_w, b_w):
+    hass = _NamedCircHass(a_w, b_w)
+    c = _named_trio(hass, _MemStore())
+    for _ in range(14):
+        await c.read_inputs()
+        await c.cycle()
+        await asyncio.sleep(0.25)
+    notes = [x for x in hass.calls
+             if x[0] == "persistent_notification"
+             and x[2].get("notification_id") == "goodwe_circulating_power"]
+    return c, notes
+
+
+_cg, _notes_g = asyncio.run(_circ_named(+3000.0, -3000.0))
+_cs, _notes_s = asyncio.run(_circ_named(-3000.0, +3000.0))
+_msg_g = _notes_g[0][2]["message"] if _notes_g else ""
+_msg_s = _notes_s[0][2]["message"] if _notes_s else ""
+print(f"       roster                     : {_cg.units}")
+print(f"       garage discharging, measured: "
+      f"{dict(zip(_cg.units, [i.batt for i in _cg.inverters]))}")
+print(f"         -> {_msg_g.split(chr(10))[2] if _msg_g.count(chr(10)) > 2 else _msg_g!r}")
+print(f"       shed discharging,   measured: "
+      f"{dict(zip(_cs.units, [i.batt for i in _cs.inverters]))}")
+print(f"         -> {_msg_s.split(chr(10))[2] if _msg_s.count(chr(10)) > 2 else _msg_s!r}")
+
+# --- THE PRECONDITIONS, AS THEIR OWN CHECKS (MUTATION.md rule 1) ------------
+check("PRECONDITION: the roster carries three DISTINCT operator-chosen names, "
+      f"none of them `UNIT_A` ({UNIT_A!r}) - so every claim below is a claim "
+      "about the roster and not about a constant that happens to equal it",
+      _cg.units == tuple(_CIRC_NAMES) and len(set(_CIRC_NAMES)) == 3
+      and UNIT_A not in _CIRC_NAMES)
+check("PRECONDITION: the two runs are MIRROR IMAGES - same house, same meter at "
+      "0 W, same magnitudes, and the two participants swapped. Without this the "
+      "direction claim below could be satisfied by a sentence that ignores the "
+      "measurement entirely",
+      [i.batt for i in _cg.inverters] == [+3000.0, -3000.0, _REST_W]
+      and [i.batt for i in _cs.inverters] == [-3000.0, +3000.0, _REST_W]
+      and _cg.grid == 0.0 and _cs.grid == 0.0)
+check("PRECONDITION: both runs actually tripped and actually raised the card, "
+      "so an absent sentence below is an absent sentence and not an absent alarm",
+      _cg.circ_wd.tripped and _cs.circ_wd.tripped
+      and len(_notes_g) == 1 and len(_notes_s) == 1)
+
+# --- AC 4: THE ATTRIBUTION ITSELF -------------------------------------------
+_WHO_G = "Right now garage is discharging while shed charges."
+_WHO_S = "Right now shed is discharging while garage charges."
+check("⚠️ THE ALARM NAMES THE TWO PACKS AND SAYS WHICH WAY EACH ONE IS PULLING. "
+      "`circulation.py` calls this the first thing somebody woken at 3 a.m. "
+      "needs and impossible to reconstruct from the watts alone, and until this "
+      "line the sentence could be deleted with all 26 files green",
+      _WHO_G in _msg_g)
+check("⚠️ AND WITH THE TWO SWAPPED, THE SENTENCE SWAPS. This is the half a "
+      "single fixture cannot have: `pos` and `neg` exchanged, or a hard-coded "
+      "sentence, satisfies the check above and fails this one. The operator is "
+      "being told which pack to walk to",
+      _WHO_S in _msg_s)
+check("...and each run carries ONLY its own sentence - the mirrored alarm does "
+      "not also contain the other direction, so the clause is derived from this "
+      "cycle's measurement rather than assembled from the roster",
+      _WHO_S not in _msg_g and _WHO_G not in _msg_s)
+check("...and the RESTING pack is not named. `cellar` is on the roster, is read "
+      "every cycle and is measured at 5 W of standby draw - `opposing()` is "
+      "called with a floor of half the trip threshold precisely so a pack idling "
+      "beside a 6 kW loop is not reported as one of its two participants",
+      "cellar" not in _msg_g and "cellar" not in _msg_s
+      and _cg.inverters[2].batt == _REST_W)
+check("...and the sentence sits with the figure, not instead of it: the same "
+      "card still carries the watts, the window and the three things only this "
+      "alarm can say",
+      all("CIRCULATING_POWER" in m and "METER CANNOT SEE" in m
+          and "CONTROL HAS BEEN STOPPED" in m and "isolator" in m
+          for m in (_msg_g, _msg_s)))
 print()
 print("   the operator's press is the only way out, and it clears BOTH halves")