Release 0.15.0: correct the SAFETY-94/97 row, add the ±170 W known issue

Review round 1 (F1-F3) on PR #173. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Release 0.15.0: bump version and close the CHANGELOG section
2026-10-05 01:23:03 +02:00 · 2026-10-05 00:48:04 +02:00 · 2026-10-05 00:45:15 +02:00 · 2026-10-05 00:13:01 +02:00 · 2026-10-04 17:27:20 +02:00 · 2026-10-04 16:57:16 +02:00
26 changed files with 2891 additions and 114 deletions
@@ -1,2 +1,2 @@
 # The admin/goodwe commit CI tests against. Bump: set to the full SHA of admin/goodwe release/1.0 HEAD (README.md, "CI and the infra pin").
-d637d0b1b13f1b863dc47e445e2ca4cf4a82fe10
+3b4ff84757f9c2c5b63a4b4a53e593ccaeafb847
@@ -1,5 +1,78 @@
 # Changelog

+## 0.15.0
+
+**A minor bump: changed behaviour, and no option changes.** No option was
+added, removed or renamed, and no default changed (83 options). Options that
+start 0.14.0 also start 0.15.0. The changes below apply with one inverter and
+with two.
+
+The add-on now learns and saves, per battery, what its power reading shows
+at rest (`unit/<name>/idle_w`). It learns it after about two quiet minutes and
+uses 0 W until then, as before. There is nothing to set.
+
+Contents of this release, in merge order since 0.14.0 (`02ed120`):
+
+| | |
+|---|---|
+| `cf705a9` | No more false "battery power reading stopped changing" errors at a new command after a rest, or at a change of phase. Each one paused control for a few seconds (several a day on a live site). A healthy battery that lags or turns around is no longer held as refusing for up to 15 min. With two inverters, a refusing battery whose reading at rest is about −100 W is now caught too. The rest value used is limited to ±75 W ([[SAFETY-94]], [[SAFETY-97]], also fixes [[SAFETY-58]]) |
+| `3129dae` | CI tests against a newer `admin/goodwe` (CI only) ([[CI-14]]) |
+
+### Known issues
+
+- A false "Battery is not keeping up" can still show when the peak guard pauses a maintenance charge ([[SAFETY-92]]).
+- After a gap in the P1 meter, the peak guard is blind for the rest of that quarter hour ([[SAFETY-90]]).
+- A battery capped at a low limit with a perfectly flat reading can still trip the stale check ([[SAFETY-74]]).
+- A battery whose reading at rest is beyond about ±170 W is still not caught when it refuses, as in 0.14.0 ([[SAFETY-97]]).
+- Two inverters: if one battery's drain stops early (e.g. switched Off), the other battery can jump to about 1.6 kW at once, and the surplus goes to the grid ([[SAFETY-95]]).
+- Two inverters: after one battery's link drops, control can stall until a safety stop ([[SAFETY-96]]).
+- Two inverters: the maintenance charge can switch on and off while the house is above the peak aim ([[SAFETY-88]]).
+- Two inverters: the "circulating" figure counts a battery's reading at rest ([[SAFETY-98]]).
+
+### If you are crossing from a version older than 0.10.0
+
+`## 0.10.0` below can refuse an old config: `slew_w` above its limit, and the
+withdrawn `price_provider` ids `engie_dynamic`, `totalenergies_dynamic` and
+`eneco_eddy`. Read it before you update. Run `tools/predeploy_check.py` with the
+bare options (`jq '.data.options'`) first.
+
+## 0.14.0
+
+**A minor bump: new behaviour with two inverters, and no option changes.**
+No option was added, removed or renamed, and no default changed (83
+options). Options that start 0.13.0 also start 0.14.0. With one inverter,
+control is the same as in 0.13.0.
+
+⭐ **Two inverters are now supported** for the monthly maintenance (drain,
+charge, hold) and the peak guard. To add a second inverter, follow
+`docs/commissioning-b.md` in the `admin/goodwe` repo. Its Stage 5, where the
+add-on takes control of it, needs 0.14.0. Read the known issues below first:
+three of them are about two inverters.
+
+Contents of this release, in merge order since 0.13.0 (`8c438ab`):
+
+| | |
+|---|---|
+| `f3e409c` | Two inverters: a battery at or under its peak reserve gives last, after the others give their full power. It is freed again above reserve + 1 point (e.g. above 21 % for a 20 % reserve). At a quarter's edge the peak guard no longer drops out for a second ([[SAFETY-91]]) |
+| `858f77c` | Two inverters: when a maintenance charge ends, for any reason, the other battery no longer starts charging from the grid; control hands over in small steps ([[SAFETY-93]]) |
+| `e51e3e0` | CI tests against a newer `admin/goodwe` (CI only) ([[CI-13]]) |
+
+### Known issues
+
+- A false "Battery is not keeping up" can still show when the peak guard pauses a maintenance charge ([[SAFETY-92]]).
+- A healthy battery that turns from charging to giving can be held at 0 W for up to 15 min ([[SAFETY-94]]).
+- After a gap in the P1 meter, the peak guard is blind for the rest of that quarter hour ([[SAFETY-90]]).
+- Two inverters: if one battery's drain stops early (e.g. switched Off), the other battery can jump to about 1.6 kW at once, and the surplus goes to the grid ([[SAFETY-95]]).
+- Two inverters: after one battery's link drops, control can stall until a safety stop ([[SAFETY-96]]).
+- Two inverters: the maintenance charge can switch on and off while the house is above the peak aim ([[SAFETY-88]]).
+
+### If you are crossing from a version older than 0.10.0
+
+`## 0.10.0` below can refuse an old config: `slew_w` above its limit, and the
+withdrawn `price_provider` ids `engie_dynamic`, `totalenergies_dynamic` and
+`eneco_eddy`. Read it before you update. Run `tools/predeploy_check.py` with the
+bare options (`jq '.data.options'`) first.
+
 ## 0.13.0

 **A minor bump: new behaviour, a new add-on page (Home, Settings, Batteries,
@@ -0,0 +1,74 @@
+# SAFETY-91 - a held battery is drawn only after the others are full
+
+**Status: DECIDED 2026-10-01 (owner: held battery last, SAFETY-25 option A
+kept).** Follows SAFETY-87. Tests: `test_safety91.py`.
+
+**The defect** (SAFETY-87 rig test, F1 and F2). At N>=2 a battery at or under
+its own peak reserve was held back (weight 0) only on cycles where the peak
+guard asked for power.
+- F1: B draining at 1000 W, A held at 15 %, house 5500. Once the grid was
+  near zero the loop set the target, A had its normal weight and B's drain
+  pin bound, so the loop drew A at 2500 W for the whole quarter (15.0 ->
+  10.7 %) while B stayed at 1000 W. In the next quarter A reached its
+  cut-out, and B stayed pinned at the peak floor (~2422 W), not its 2500 W.
+- F2: in a HOLD (A holding, B held), at a quarter's edge the guard saw a block
+  with no seconds left and asked for nothing for one cycle. The HOLD's
+  ceiling lapsed, A went back to 0 W and the loop's target went to B: 2500 W
+  for 1 s.
+
+**The fix** (`main.py`, N>=2 only).
+- `_held_back()`: the batteries at or under their own reserve while another
+  can still give (live, not refusing), graded as in `_peak_on_able()`. They
+  weigh 0 in every split where the site gives, not only for the peak. With
+  nobody able (all held, or the rest refusing or dropped) nobody is held back
+  and the split is as before.
+  Review: once held back, a battery stays so until its SoC reads more than 1
+  point above its reserve. A reading flipping 20/21 % otherwise swapped
+  ~1000 W between the batteries on each flip (grid +-500 W with A 10 s and
+  B 3 s lag). The guard's own permission (SAFETY-87) is unchanged.
+- `_drain_rise()`: while a battery is held back, a draining battery's pin
+  becomes a floor at its drain rate (`lo`), so it rises towards its rating
+  before the held one gives. Not for a held battery's own drain, not under a
+  site stop, not for a battery that is not live.
+- `tariff.next_quarter()`: past a block's end, before the next block's first
+  telegram, the guard grades the next quarter, projected from the held
+  reading (the averager credits it there). Not when that reading is too old
+  to be credited (`max_hold_s`).
+
+**What stays.** SAFETY-25 option A: once every able or draining battery is
+at full power, the loop still draws a held battery (`allocator._fill()`'s
+last-resort pass). With house 5500 and 2 x 2500 W, A still gives 2500 W
+after B is full. Nothing is placed on a battery at its cut-out: OPT-09's
+pack limit closes it (`hi = 0`), and the drain rise lets B take the rest.
+
+**Before -> after** (`test_safety91.py`, 2 x 2500 W, lagging battery 10 s):
+
+| case | before | after |
+|---|---|---|
+| B drain 1000, A held, house 4000 | A 2500, B 1000 | A 1500, B 2500 |
+| same, house 5500 | A 2500, B 1000 | A 2500, B 2500 (option A) |
+| cycles A asked while B not full | 612 of 900 | 0 |
+| A at its cut-out, house 5500: B | 1572 W mean | 2500 W, A 0 W |
+| HOLD, late telegram at the edge | A 0, B 2470 for 1 cycle | A 2050, B 0 |
+| idle, A held, house 2000 | A 1005, B 1005 | A 0, B 2020 |
+| N=1, every scenario | | byte-identical |
+
+**Why N>=2 only.** At N=1 there is no other battery to give first. The edge
+roll would also fix the N=1 one-cycle dip at a quarter's edge (SAFETY-86
+rig, "A dropped to 0 W for 1 s"), but this ticket keeps N=1 byte-identical;
+extending it is a one-line change for a later ticket.
+
+**Re-pinned.** `test_modes.py` `n2` and `n2_off`: from t=1600 battery A is
+at its 20 % reserve, so B carries the house and A gives last (100 of 540
+cycles differ). With SAFETY-87's held rule both are a5dddad's again, and the
+test grades that.
+Two fixtures changed with it: `test_safety87.py` part 10's "without the
+raise" run also turns off `_drain_rise()` (else B rises anyway), and
+`test_peakguard.py` 10g and `test_watchdog.py`'s two-inverter rig give
+their second battery a cut-out, as rule 8 requires (an unknown cut-out is held, so A alone would carry the cycle).
+
+**Not changed.** The peak guard's own rules (SAFETY-87). A drain with
+nobody held stays a pin (SAFETY-78). An Off battery beside a held one
+(SAFETY-87 Open). The first cycle after start, before any quarter is
+measured, can still put the loop's first step on a held battery in a HOLD.
+SAFETY-88, -89, -90, -92, -93, -94.
@@ -0,0 +1,60 @@
+# SAFETY-93 - the maintenance charge end hands back smoothly
+
+**Status: implemented 2026-10-02, for review.** Tests: `test_safety93.py`.
+
+**The defect** (SAFETY-85 rig test, check 4; also on 9358781). At N=2, when
+A's maintenance charge ended, B went 0 -> -1600 W in one cycle and charged
+from the grid with the house at 6000 W. The HOLD end was already smooth
+(SAFETY-85).
+
+**Cause.** During the charge the site target holds A's charge (SAFETY-84's
+`charge` ceiling, -2000 W). At the end A gets its HOLD pin (0 W), but the
+loop starts its next step from last cycle's site target. The slew limit
+moves the site total by 400 W (-2000 -> -1600), and the only battery left
+to place it on is B. The same happens when the charge times out or the
+battery is switched Off (A free, its -2000 W shared out). With the charge
+suspended by the guard and A giving under the loop, B took A's share in
+one step (675 W).
+
+**The fix** (`main.py`, `_reseed_charge_end()`, N>=2 only). On the cycle a
+battery leaves CHARGE, the loop's start point (`self.target`, and the
+integrator with it) is what the other batteries stood at plus that
+battery's new command: its pin (HOLD or abort, 0 W), or, if it is free, its
+last discharge (a charge stops). The loop then moves from there one slew
+step a cycle. The ending battery's own step (-2000 -> 0 W) is maintenance's
+pin, as before; it lowers the grid import. The end is kept until the loop
+next runs, so a missed poll on that cycle (the input hold) does not lose it.
+
+Review: a charge also ends, for the site, when the battery is still in
+CHARGE but can no longer be placed: a stale link or a refusal (SAFETY-73)
+drops it, and its -2000 W landed on B the same way (B 0 -> -1600 W at a
+1200 W house). So the end is noted after the unit claims are filed: a
+battery leaves the charge when it leaves CHARGE, is not live, or its own
+claims contradict. The guard suspending the charge (SAFETY-84) is no end.
+
+Why a start-point reseed, and not a per-battery slew in the allocator: the
+jump comes from one stale number at one edge, the kind of edge SAFETY-73
+(`_unit_refusal_end`) and OPT-11 P3 (`_reseed_run_edge`) already reseed.
+The change stays at that edge; nothing else at N>=2 moves.
+
+**Before -> after** (`test_safety93.py`, 2 x 2500 W, 10 s lag, 2 s meter):
+
+| case | before | after |
+|---|---|---|
+| rig case: house 6000, A charges 2000 to the end | B 0 -> -1600, charges 4 cycles | B 0 -> 400 -> 800 ..., never charges |
+| house 1200 | B 0 -> -1600 (2800 W from the grid) | B steps of 400, never charges |
+| charge times out / A switched Off | B 0 -> -1600 | B 0 -> 400 |
+| guard suspended the charge, A gives 1825 | B step 675 W | B step 395 W |
+| missed poll on the end cycle | B 0 -> -1600 a cycle later | B 0 -> 400 |
+| A dropped mid-charge (stale link, refusal), house 1200 | B 0 -> -1600 | B 0 -> 400 |
+| N=1, both charge ends above | | byte-identical |
+
+No pinned digest moved: the 46 digests of `tools/*identity*.py` (N=1 and
+N=2) are byte-identical to f3e409c; none of their scenarios reaches a
+charge end.
+
+**Not changed.** The peak guard's floor still moves the site in one step
+when it engages (a house step, a quarter edge): the guard outranks the slew
+(owner order). A HOLD pin still drops the holding battery to 0 W at once
+and SAFETY-86 gives way to the others first. SAFETY-88 (charge flapping
+above the aim) is untouched.
@@ -0,0 +1,102 @@
+# SAFETY-94 - a battery that lags or reverses is not frozen or refusing
+
+**Status: implemented 2026-10-03, for review.** Tests: `test_safety94.py`
+(rig: `tools/safety94_rig.py`). Also closes SAFETY-58. SAFETY-74 stays open.
+
+## The defects
+
+1. **Stale-reading gate (SAFETY-37).** Its 35 s ran from the register's last
+   change. After a rest that clock was already past 35 s, so the first read
+   after a new command tripped it, before the register could answer. Live
+   2026-10-03 (0.14.0, N=2): 17:39:16 B and 17:39:25 A (load ramp after a
+   rest), 19:00:04 A (drain start), 21:21:22 B (drain -> charge). Each was
+   1 s after its command; each register answered within 11 s. This is
+   SAFETY-58's shape.
+2. **Refusal at N=1 (SAFETY-52).** `compute()` engaged after `SETTLE_CYCLES`
+   frozen cycles if the reading was under 100 W at that moment. The frozen
+   cycles include a reversal through the battery's lag. At a 1 s meter the
+   12th cycle comes as a battery reversing out of a charge passes 0 W
+   (SAFETY-85 rig, O1: "gave -20 W for 13 cycles"). The refusal then held
+   0 W, the battery settled at 0 W, never gave 100 W, and waited for the
+   15-minute probe. N>1 already required 22 s in the band, so it was safe
+   at a 10 s lag but not at 20 s.
+
+## What changed
+
+- **The gate counts only time the register was asked to move**
+  (`freshness.Freshness._oblige`). A read counts the time since the last
+  read when, at that read, the command is 250 W or more and has moved 250 W
+  from where it stood at the register's last change. A register change
+  (or a SAFETY-57 release) restarts the count. A command flapping in and
+  out of the ask still adds up (frozen register, 0/1500 W every 5 s: trip
+  at 69 s). The conjunction, `MOVE_W` and `RELEASE_S` are unchanged.
+- **The bound is unchanged at 35 s and now means what its derivation
+  says.** The floor was always "how long a healthy register takes to answer
+  a command": 6 s plant + 10 s publish + 1 s read = 17 s. The band
+  `[2 x 17, 0.5 x 75] = [34, 37.5]` holds. Live answers measured: 1.4, 3,
+  6 and 11 s after the command.
+- **Refusal evidence is the same at every roster size**
+  (`main.Controller._gave_nothing`, SAFETY-73's count moved into a method).
+  The reading must stay under 100 W, one way, while asked over 200 W, for 12
+  cycles spanning 22 s. At N=1 `compute()` gets this as `gave_nothing` and
+  needs it on top of its own freeze test. `None` (compute alone) keeps the
+  old law.
+- **The evidence restarts when the reading moves 50 W towards the ask**
+  (`REFUSED_PROGRESS_W`). A refusing battery reads flat (-3/-4 W live). Live
+  readings wander by under 25 W at rest. A first-order lag crossing the band
+  gains 50 W in at most 0.4 tau, so it cannot fill 22 s unless tau > 54 s.
+  This also covers B, whose reading is 100 W below its power.
+
+## Bounds and worst-case catch
+
+| fault | before | after | budget |
+|---|---|---|---|
+| register frozen, then asked to move | 0-35 s after the ask (often 1 s) | 35 s after the ask (+1 read) | SAFETY-37: 35 s, under the 75/85 s consumer holds |
+| register frozen at rest reading ~0 W | stale 1 s after the ask | refused or stale, 0 W within 23-35 s | the same |
+| refusing battery, 1 s meter, N=1 | 11-16 s | 22-28 s | SAFETY-73's 22 s span (+ one 10 s publish) |
+| refusing battery, 2 s meter | 22-28 s | 22-28 s | unchanged |
+| refusing battery, 5 s meter | N=1 35-41 s, N=2 41-55 s | N=1 40-45 s, N=2 50-55 s | 12 cycles = 55-60 s |
+
+Rig: `test_safety94.py` part 3. A release after SAFETY-57 still exposes
+the held number for one 35 s window of asking, so 35 < 75 < 85 still holds.
+
+## Before -> after
+
+- Live replay (part 1): 4 trips -> 0.
+- Refusing B (its -100 W idle reading): see SAFETY-97.
+- Rig, 10 s lag, N=1 and N=2, 1/2/5 s meters, two register shapes, 48 runs
+  (part 2): before 27 stale trips and 1 refusal, after 0 and 0.
+- Reversals, lag 10 and 20 s, 1 s meter (part 2): before N=1 6 stale / 3
+  refused, N=2 6 / 1; after 0 / 0.
+- 16-day loop capture (`test_freshness.py` part 8): 93 trips -> 59. Trips
+  answered within 20 s: 21 -> 1. Two of the removed trips were not quick:
+  a register held 351 s under a command hovering at the 250 W travel edge
+  (under 35 s of asking before it moved; survivor 2's shape), and a
+  refusing battery the gate had caught only on a passing ramp (SAFETY-52's
+  refusal covers it).
+
+## SAFETY-58 and SAFETY-74
+
+- **SAFETY-58 is fixed** by this change: its card asks for the clock to
+  start with the obligation and for the bound to be re-derived. Both are
+  done above. `test_freshness.py` survivor 5 is now graded as closed.
+- **SAFETY-74 is not fixed.** A battery capped at 300 W with a perfectly
+  flat reading, 5 s meter, house stepping: 50 trips/h at N=1 and 80 at N=2
+  before, 37 and 60 after. With +-1 W dither: 0. A flat reading under a
+  command that moved is exactly what the gate is for; telling "limited"
+  from "frozen" needs a second signal (the meter, or SoC).
+
+## Known gaps
+
+- ~~B's standby offset (-95 to -118 W at idle) puts a refusing B outside the
+  100 W band, so a refusing B never latched (review F1: at N=1 new, at N=2
+  as before).~~ **Fixed by SAFETY-97 in the same PR:** the band is centred
+  on each unit's learned idle reading. `SAFETY-97-idle-offset.md`.
+- A command that asks only part of the time (a fraction d) is caught after
+  35 s of asking, which is 35/d s of wall time (0/1500 W every 5 s: 69 s).
+  SAFETY-30's per-unit check restarts when its command stops opposing the
+  held reading, which a lapsing ask normally does, so 35 < 85 holds there.
+  SAFETY-31's circulation check (75 s) ignores the command, so its margin
+  holds only while d >= 0.47.
+- A register frozen under a command that stays near the 250 W travel edge
+  is caught late or not at all (survivor 2).
@@ -0,0 +1,118 @@
+# SAFETY-97 - "gives nothing" is graded against each battery's idle reading
+
+**Status: implemented 2026-10-04, folded into PR #171 (SAFETY-94), for
+review.** Owner decision 2026-10-04: the band's centre is clamped to
+-75 W (see Bounds). Tests: `test_safety97.py` (rig: `tools/safety94_rig.py`).
+Closes SAFETY-94 review finding F1.
+
+## The defect
+
+B's power reading (board B's `inverter_ac_power`, 0x0518) shows -95 to -118 W
+at idle: its standby draw (the GoodWe app shows 0 W). A's shows -2 to -4 W.
+Every "the battery gives nothing" test was `|reading| < 100 W`, so a refusing
+B sat on the band's edge and never latched:
+
+- N=2: never caught, before or after SAFETY-94.
+- N=1: the old one-instant check caught it in 17-105 s; SAFETY-94's shared
+  rule (12 cycles in the band in a row) never did (review probe, 1200 s).
+
+## Design
+
+- **Offset source: learned per unit** (`app/idle.py`, `Inverter.idle`). No
+  new option: a required one is a setup step every client gets wrong, and an
+  optional one is a second source to reconcile. An override can be added
+  later if a site needs one.
+- **When it learns:** control runs; the unit is not refused (unit or site),
+  stale or sign-tripped; its command has been within 50 W (`IDLE_ASK_W`) for
+  120 s (`IDLE_QUIET_S`, 6 lags of 20 s). A refusing battery is asked more
+  than 50 W, and while refused it does not learn, so its refusal cannot be
+  learned as idle. A capped battery under a big ask is not sampled either.
+- **How:** the first value is the mean of 120 s of samples; then it follows
+  drift with a 30 min time constant. A sample beyond 250 W (`IDLE_SAMPLE_W`)
+  is dropped (a register held at a giving value). The band is centred on
+  the value clamped to 75 W (`IDLE_MAX_W`; owner decision below).
+- **Restart:** saved per unit (`unit/<name>/idle_w`, on first learn and each
+  5 W move) and restored, clamped to 250 W. Without it a battery refusing from the
+  start is never quiet, so never learned, so never caught.
+- **Until learned the idle reading is 0 W**: the rule as it was.
+
+## Not chosen: the GoodWe LAN integration's DC battery power
+
+Both inverters also appear through HA's GoodWe integration (B:
+`sensor.kelder_dyness_battery_power`, 0 W at idle; found read-only on the
+live HA 2026-10-04). Pointing `batt_entity` at it removes B's offset by
+configuration, but:
+
+- the band must be safe without it: other installs may not have it;
+- it is polled over UDP on the inverter's Wi-Fi, a second channel that can
+  drop while the board keeps reading (HW-01 lost both once); a missing
+  reading stops the site;
+- SAFETY-37's 35 s bound is derived from the board's 10 s publish; the
+  integration's poll interval (believed 10 s, not checked here) and latency
+  are not measured;
+- DC power is not 0x0518, which SAFETY-30/31/42 were measured against.
+
+It stays an install choice to test on the rig, not a code change here. With
+it, the learned idle reading is simply ~0 W.
+
+## Where it applies
+
+Every test of "gives nothing / gives / takes" now uses `reading - idle`:
+
+| check | change |
+|---|---|
+| shared refusal evidence `_gave_nothing` (N=1 and N>=2) | centred |
+| N=1 engage and end in `compute()` (`idle_w`, the site sum) | centred |
+| N=1 end in `_refusal_update` | centred |
+| N>1 unit end (probe answered, takes the other way) | centred; uncentred, B's idle -100 W read as "takes 100 W" and ended a charge refusal at once |
+| stale-path refusal (`_refusal_from_stale`, N=1 and N>1) | centred |
+| SAFETY-42 "parked" (small ask, gives nothing) | centred |
+| SAFETY-37 stale gate | unchanged: it grades register changes against command travel, not a level |
+| SAFETY-57 release | unchanged: it reads the command only |
+| SAFETY-30 per-unit sign | unchanged: opposition needs both over 250 W; B's 100 W idle cannot make or hide one alone |
+| SAFETY-42 shortfall | unchanged: B reads ~100 W short at every power, which errs towards reporting (report only) |
+
+## Bounds: owner decision 2026-10-04 (review R1)
+
+Band: `|reading - centre| < 100 W`, centre = idle clamped to +-75 W.
+
+- **Why a clamp under the band.** A wrong idle reading (taught during a
+  rest while the reading shows something else, e.g. a grid top-up of a unit
+  held at 0 W, or restored onto a swapped inverter) more than about 100 W off
+  hid every refusal on that battery, at N=1 and N=2; with the first +-250 W
+  clamp the rig missed a refusing A whenever the error was 110-250 W. At
+  +-75 W the band always keeps 0 W +-25 W, so a battery reading about 0 W
+  while refusing is caught whatever was learned or restored, and a wrong idle
+  cannot refuse a healthy 0 W battery (its ask is over 200 W).
+- **The trade-off.** Options: keep +-250 W (covers idle readings to about
+  +-350 W, any 100 W mis-learn hides refusals); clamp to +-75 W (chosen);
+  "old band or centred band" (rejected: a correct B would need to give 200 W
+  to answer its 200 W probe).
+- **Cost.** A battery whose idle reading is beyond about +-170 W is centred
+  at most 75 W out, so its refusal falls outside the band: it behaves as in
+  0.14.0 (not caught by this rule). B (-95 to -118 W) reads 20-43 W from its
+  clamped centre. B is caught across -150..+90 W of error in its idle
+  reading; learned 110 W or more too high it is missed, as in 0.14.0 at N=2.
+- A frozen register is still caught by the stale gate at 35 s of asking.
+- Recovery from a wrong value needs quiet time: tau 30 min.
+
+## Catch times (rig, refusing from 200 s after a 400 s rest, +-4 W)
+
+| refusing | meter 1 s | 2 s | 5 s |
+|---|---|---|---|
+| A, N=1 | 28 s (before 28) | 28 (28) | 65 (65) |
+| A, N=2 | 28 (28) | 28 (28) | 110 (110) |
+| B, N=1 | 28 (never) | 28 (never) | 65 (never) |
+| B, N=2 | 24 (never) | 24 (never) | 60 (never) |
+
+A at N=2 on a 5 s meter is 110 s here because the rig's grid goes flat once
+A is cut, so the loop cycles on the 15 s floor; the same run on the PR before
+SAFETY-97 gives 110 s. B restored after a restart, refusing from the start:
+24 s; with nothing saved: never.
+
+## Before -> after
+
+- Healthy B with its offset, SAFETY-94's four scenarios, N=1 and N=2, 1/2/5 s
+  meters, both register shapes, idle learned or restored (96 runs): 0 stale,
+  0 refused. Reversals, lag 10/20 s, idle restored: 0.
+- Live replay (SAFETY-94 part 1): 0 trips (the gate is untouched).
@@ -590,7 +590,7 @@ accumulator is doing:
 | `freeze-released` | the freeze had run out of plant-shaped explanations and the command was let move again |
 | `mode-bound` | the batteries' limits set the command, not the meter: their battery modes, or, with two or more inverters, a battery in its monthly maintenance |
 | `not-running` | control is stopped **and** shadow mode is off, so the loop did not run |
-| `battery refuses` | the battery gave less than 100 W for 12 cycles (a minute at a 5-second meter) while asked for more than 500 W, so the add-on asks 0 W in that direction (see below) |
+| `battery refuses` | the battery gave less than 100 W for 12 cycles and at least 22 s (a minute at a 5-second meter) while asked for more than 500 W, so the add-on asks 0 W in that direction (see below) |
 | `battery probe` | the add-on asks 200 W to test whether a refusing battery gives power again |

 **When the battery refuses.** At its cut-out level the battery gives nothing,
@@ -600,7 +600,11 @@ request, and the `Why` row reads *The battery refuses to give power: 0 W*. Every
 the battery gives 100 W or more, when the grid needs charging instead, and when
 control is stopped or started. 200 W is below the 250 W the stale-reading check
 needs, so a test never trips it. A battery that gives some power, even 100 W,
-is not refusing and keeps its request.
+is not refusing and keeps its request. Nor is a battery whose reading is
+still moving towards the request, such as one turning from charging to
+giving (SAFETY-94). "Gives" is counted from what the battery's reading shows
+at rest, which the add-on learns after two quiet minutes and keeps: some
+inverters show about -100 W at rest (SAFETY-97).

 **With two or more inverters** the same rule works per inverter. An inverter
 whose battery gives less than 100 W for 12 cycles, and at least 22 s, while
@@ -1640,7 +1644,7 @@ help - see "Why the tuning is what it is".
 | `maintenance_enabled` | false | Enable the monthly cycle |
 | `maintenance_interval_days` | 28 | Minimum gap between cycles |
 | `maintenance_start_hour` | 10 | Hour of day a due cycle begins |
-| `maintenance_discharge_w` | 2000 | Drain rate (exports the surplus). The peak guard may ask for more (SAFETY-83; at N≥2 while another battery is at its peak reserve, SAFETY-87). Above `max_w` it is **clamped** to `max_w` — the drain phase SETs the setpoint and the arbiter bounds it, saying so on the status page (`limited by supervised(max_w)`). Warned about, not refused: the cycle still completes, just slower |
+| `maintenance_discharge_w` | 2000 | Drain rate (exports the surplus). The peak guard may ask for more (SAFETY-83; at N≥2 while another battery is at its peak reserve, SAFETY-87), and at N≥2 so may the house while another battery is at its peak reserve (SAFETY-91). Above `max_w` it is **clamped** to `max_w` — the drain phase SETs the setpoint and the arbiter bounds it, saying so on the status page (`limited by supervised(max_w)`). Warned about, not refused: the cycle still completes, just slower |
 | `maintenance_charge_w` | 2000 | Charge ceiling, capped again by peak headroom. Must stay **at or below `max_w`** or the cheap-window shaping (`hi = -maintenance_charge_w`) contradicts the supervised limit (`lo = -max_w`), the arbiter resolves it to **0 W**, and maintenance silently never charges in a cheap window — **the add-on refuses to start** |
 | `maintenance_soc_floor` | 11 | Drain target — stay just above the inverter's own floor. ⚠️ **This is not `peak_soc_floor`.** It is the depth the monthly recalibration deliberately goes to, once, on purpose; `peak_soc_floor` is the depth a money-saving discharge may never reach on any day. The right values differ (11 vs 20 as shipped), which is why they are two keys |
 | `maintenance_soc_target` | 99 | Charge target |
@@ -1667,6 +1671,9 @@ others only add power when the house needs more; none charges while it drains
 (SAFETY-78). Below the drain rate the rest is exported, as with one battery.
 If the house would still go over the peak limit, the battery being emptied
 gives more than its drain rate, with one battery too (SAFETY-83).
+A battery at its peak reserve gives last: the others give their full power
+first, and the battery being emptied rises above its drain rate before it
+(SAFETY-91).
 In a cheap window the battery being filled charges and the others only add
 charge; none gives while it charges. The charge is cut to what keeps the
 15-minute peak at the limit minus `peak_margin_w` (SAFETY-84).
@@ -1674,6 +1681,8 @@ While a full battery rests after its charge (the hold), it gives just enough
 to keep the 15-minute peak at that aim if the house needs it; with two
 batteries the other one gives first. The hold still ends on its clock
 (SAFETY-86).
+When a charge ends, the other batteries take over one slew step a cycle,
+and none starts charging from the grid (SAFETY-93).

 #### Capacity-tariff exposure of the grid-following loop

@@ -1809,7 +1818,9 @@ exactly like the SoC drift the monthly maintenance cycle exists to correct.
  It will discharge straight past this number and keep going until the pack's own
  BMS cut-out stops it. What you are promised by `peak_soc_floor: 20` is *"the
  capacity-peak guard will not spend the pack for money below 20 %"*, and
-  **nothing more**. See below for what that costs on a real evening.
+  **nothing more**. See below for what that costs on a real evening. With two
+  or more batteries, one under it is used last: only once the others give
+  their full power (SAFETY-91).
 - **When it binds you are told**, once per episode, with notification
  `goodwe_peak_soc_floor` and a red status-page row reading *Battery at its
  peak reserve* (`PEAK_GUARD_FLOOR_LIMITED` in the log): the quarter **will**
@@ -3450,7 +3461,8 @@ reason code, and its full figures are on the DEBUG line right after it and in
  …`, and the peak guard's full reason is on the DEBUG line after its ERROR.
 - ***name*: battery power reading stopped changing** is SAFETY-37/56/57. The
  ERROR line says when it clears and names `STALE_READING`. The full reason,
-  with both possible causes, is on the DEBUG line after it.
+  with both possible causes, is on the DEBUG line after it. The 35 s counts
+  only while the command asks the reading to move (SAFETY-94).
 - **Meter: no reading for …** (red): the add-on logs one WARNING when the
  meter goes quiet, "No meter reading for …", and an INFO line when readings
  return, at most once every 10 minutes. Past `stale_input_s` the **Why**
@@ -737,9 +737,9 @@ def resolve(claims: list, *, units=None, weights=None, live=None,
    gate, held = _unit_modes(out, site_claims, bounds, live)
    if callable(weights):
        weights = weights(out.target_w)
-    # SAFETY-87: units under their peak reserve weigh 0 while the site gives,
-    # so the others carry the peak floor. An Off battery gives the peak's
-    # shortfall, so it goes before them when no other unit is left.
+    # SAFETY-87/91: units under their peak reserve weigh 0 while the site
+    # gives, so the others carry the target first. An Off battery gives the
+    # peak's shortfall, so it goes before them when no other unit is left.
    reserve = set(reserve) if out.target_w > 0.0 else set()
    if held and reserve and not set(bounds) - held - reserve:
        held = set()
@@ -484,6 +484,8 @@ def compute(
    refused: int | None = None,
    probe: bool = False,
    bound: tuple | None = None,
+    gave_nothing: bool | None = None,
+    idle_w: float = 0.0,
 ) -> Decision:
    """One control cycle. A cycle is one meter update (~5 s on a HomeWizard P1).

@@ -497,6 +499,13 @@ def compute(
    `bound`    OPT-11: `(lo, hi)`, what the batteries may place this tick with
               their modes applied (`allocator.loop_bound()`), or None. See
               MODE_BOUND below. None is the law as it was.
+    `gave_nothing` SAFETY-94: the caller's span check - the reading stayed
+               under REFUSED_BELOW_W, one way, for SETTLE_CYCLES spanning
+               REFUSED_SPAN_S. A refusal engages only with it. None leaves it
+               out (compute() alone, as before).
+    `idle_w`   SAFETY-97: what `actual_w` reads while the batteries give
+               nothing (app/idle.py). The refusal's band and its end are
+               centred on it. 0 is the law as it was.
    """
    reason = "tracking"
    # OPT-11: a bound that leaves out 0 W would FORCE a direction, which no
@@ -817,13 +826,18 @@ def compute(
    # `saturation_w` is a refusal, not a slow plant. The drop to 0 skips the slew
    # limit because it only removes an ask the battery is not meeting.
    if refused is not None:
+        # SAFETY-94: and only when the reading has given nothing for the
+        # whole span, not just now. `sat_count` also counts the cycles a
+        # healthy battery spends reversing through its lag (-2000 W towards
+        # +800 W): at a 1 s meter its 12 cycles end as the reading passes 0.
        if (refused == 0 and frozen and sat_count >= SETTLE_CYCLES
                and abs(prev_w) > tuning.saturation_w
-                and abs(actual_w) < REFUSED_BELOW_W):
+                and abs(actual_w - idle_w) < REFUSED_BELOW_W
+                and gave_nothing is not False):
            refused = 1 if prev_w > 0 else -1
        if refused and refused * i_w < 0:
            refused = 0                          # the loop wants the other way
-        elif refused and refused * actual_w >= PROBE_ANSWER_W:
+        elif refused and refused * (actual_w - idle_w) >= PROBE_ANSWER_W:
            refused = 0                          # it delivers: a probe answered,
            #                                     or a slow reading arriving
        elif refused:
@@ -87,6 +87,10 @@ when it has not moved THROUGH A CHANGE IT WAS OBLIGED TO FOLLOW:
                AND |standing command now - standing command when the reading
                     last changed| >= MOVE_W

+SAFETY-94: "unchanged for" counts only the reads at which both command terms
+held, so a register that rested is not judged before it could answer.
+DECISIONS/SAFETY-94-lagging-battery.md.
+
 0x0518 is the inverter reporting ITSELF and it tracks its own command: r = 0.998
 with battery power against r = 0.09 with the real meter (goodwe/NOTES.md §3.3),
 command and actual agreeing within 4 W once settled (§5.10, 2026-08-22), and the
@@ -216,6 +220,8 @@ change - which was the ONLY exit - has a median of 143 s, 17 episodes at or
 over the live one's 710 s, and a worst case of 21440 s. That distribution is a
 property of this battery's firmware. It is not a property of this code, and the
 add-on must not depend on it.
+SAFETY-94: many were the gate judging a rested register on its first read
+(SAFETY-58). Counted from the ask, the same days give 59 trips.

 THE RULE, and it is SAFETY-13's shape one module over - "which latches get an
 exit, not how long the block lasts":
@@ -372,7 +378,9 @@ BOUNDS = {
                   "SAFETY-57: the verdict is withdrawn after 17.0 s of the "
                   "standing command below 250 W, because at 0 W the register "
                   "is obliged to nothing and the verdict cannot be tested "
-                   "again from inside the state it creates"),
+                   "again from inside the state it creates. SAFETY-94: the "
+                   "35 s counts only reads at which the command asks the "
+                   "register to move"),
    "soc": Bound(
        signal="soc (0x050E, pack SoC, U16, 1 %, 10 s publish)",
        unchanged_s=float("inf"),
@@ -416,11 +424,9 @@ class Freshness:
    new grading window at that instant. The 1 Hz oscillation the latch exists to
    prevent is still prevented: the new window is `bound.unchanged_s` wide, so
    no re-trip can land sooner than 35 s after a release, rather than on the
-    next read. ⚠️ MEASURED FROM THE RELEASE, NOT FROM THE COMMAND RESUMING - if
-    the site rests for longer than the window before it asks for anything, the
-    window is already old and the re-trip lands on the first read at which the
-    command travels 250 W again. That is survivor 5's shape, it predates this
-    card, and its cost is one `stale_input_s` hold.
+    next read. SAFETY-94: the 35 s counts only while the command asks the
+    register to move, so a site that rests after a release is not re-tripped
+    on its first ask.

    ⚠️ TWO CLOCKS, AND THE DISTINCTION IS THE WHOLE OF SAFETY-57'S HONESTY.
    `changed_mono` / `held` are facts about the REGISTER: when it last carried a
@@ -451,6 +457,11 @@ class Freshness:
        # the change-stamps; `_release()` is where they diverge.
        self.graded_from = None
        self.standing_at_grade = None
+        # SAFETY-94. Seconds of this window during which the register was
+        # obliged to move (the command at least `move_w` and `move_w` away
+        # from `standing_at_grade`), and the instant of the last read.
+        self.obliged_acc = 0.0
+        self.last_read = None
        # The instant the standing command last FELL below `move_w`, or None
        # while an obligation is standing. The release timer runs off this.
        self.rested_since = None
@@ -499,6 +510,7 @@ class Freshness:
        # it reads in the order the state machine moves - withdraw, then
        # re-grade - not because the code depends on it.
        self._release(standing_w, now_mono)
+        self._oblige(standing_w, now_mono)
        self._grade(standing_w, now_mono)

    def _open_window(self, standing_w, now_mono) -> None:
@@ -510,6 +522,35 @@ class Freshness:
        self.graded_from = float(now_mono)
        self.standing_at_grade = (None if standing_w is None
                                  else float(standing_w))
+        # The read that opens a window is never an ask (no travel yet).
+        self.obliged_acc = 0.0
+
+    def _obliged(self, standing_w) -> bool:
+        """Is the register asked to move: the command is at least `move_w` and
+        has travelled `move_w` since the window opened?"""
+        if standing_w is None or self.standing_at_grade is None:
+            return False
+        standing_w = float(standing_w)
+        return (abs(standing_w) >= self.bound.move_w
+                and abs(standing_w - self.standing_at_grade)
+                >= self.bound.move_w)
+
+    def _oblige(self, standing_w, now_mono) -> None:
+        """SAFETY-94. Count only the time the register was asked to move.
+
+        A register that held still while nothing asked it to move has not
+        failed, so time before the command moved is not evidence. The time
+        since the previous read counts when the obligation stands at this
+        read; a command flapping in and out of the obligation still adds up.
+        """
+        now_mono = float(now_mono)
+        if self.last_read is not None and self._obliged(standing_w):
+            self.obliged_acc += max(0.0, now_mono - self.last_read)
+        self.last_read = now_mono
+
+    def obliged_s(self) -> float:
+        """Seconds of the current window the register was obliged to move."""
+        return self.obliged_acc

    def _release(self, standing_w, now_mono) -> None:
        """SAFETY-57. Withdraw a verdict whose obligation is no longer standing.
@@ -543,7 +584,12 @@ class Freshness:
        if self.stale or self.graded_from is None:
            return
        held_s = self.graded_s(now_mono)
-        if held_s < self.bound.unchanged_s:
+        # SAFETY-94 (closes SAFETY-58): the bound counts only the time the
+        # command asked the register to move, not the time since it last
+        # changed. A register that rested for minutes was otherwise judged on
+        # the first read after a new command, before it could answer (live,
+        # 2026-10-03: 1 s after the command).
+        if self.obliged_s() < self.bound.unchanged_s:
            return
        # ⚠️ BOTH None GUARDS ARE FOR A CALLER THAT DOES NOT KNOW ITS OWN
        # OBLIGATION YET, WHICH IS NOT `_read_unit`. `Inverter.standing_w()`
@@ -0,0 +1,87 @@
+"""SAFETY-97: what a battery's power reading shows while it gives nothing.
+
+B's reading (0x0518) shows -95 to -118 W at idle (standby draw, live
+2026-10-03); A's shows -2 to -4 W. "The battery gives nothing" is graded
+against this idle reading, not against 0 W, or a refusing B never latches.
+DECISIONS/SAFETY-97-idle-offset.md.
+
+Learned per unit, never configured:
+- only while control runs, the unit is not refused, stale or tripped, and
+  its command has been within IDLE_ASK_W for IDLE_QUIET_S (a refusing battery
+  is asked more than that, so it cannot teach its refusal as idle);
+- a reading beyond IDLE_SAMPLE_W is not a sample;
+- first value: the mean of IDLE_FIRST_S of samples; then a slow follow
+  (IDLE_TAU_S);
+- persisted per unit and restored, clamped to IDLE_SAMPLE_W, at start.
+The band is centred on it clamped to IDLE_MAX_W (owner, 2026-10-04). Until
+learned the idle reading is 0 W, the rule as it was.
+"""
+
+import math
+
+IDLE_MAX_W = 75.0       # |idle| used: under the 100 W band, so it keeps 0 W +-25 W
+IDLE_SAMPLE_W = 250.0   # a reading beyond this is not a sample
+IDLE_ASK_W = 50.0       # a command this small counts as "asked ~0"
+IDLE_QUIET_S = 120.0    # 6 lags of 20 s: a 2500 W step has decayed to 6 W
+IDLE_FIRST_S = 120.0    # seconds of samples averaged for the first value
+IDLE_TAU_S = 1800.0     # then follow drift this slowly
+IDLE_SAVE_W = 5.0       # persist when the value moved this far
+IDLE_GAP_S = 10.0       # a longer gap between reads counts as this
+
+
+def _num(v):
+    try:
+        v = float(v)
+    except (TypeError, ValueError):
+        return None
+    return v if math.isfinite(v) else None
+
+
+class IdleReading:
+    """One unit's idle reading. `w` is what "gives nothing" is centred on."""
+
+    def __init__(self, saved=None):
+        v = _num(saved)
+        self.value = (None if v is None
+                      else max(-IDLE_SAMPLE_W, min(IDLE_SAMPLE_W, v)))
+        self.saved = self.value
+        self.quiet_since = None
+        self.last = None
+        self.acc_w = 0.0
+        self.acc_s = 0.0
+
+    @property
+    def w(self) -> float:
+        """The centre used: the learned value clamped to IDLE_MAX_W."""
+        if self.value is None:
+            return 0.0
+        return max(-IDLE_MAX_W, min(IDLE_MAX_W, self.value))
+
+    def observe(self, reading, standing_w, now_mono, may_learn) -> bool:
+        """One read. Returns True when the value should be persisted."""
+        now = float(now_mono)
+        dt = (0.0 if self.last is None
+              else max(0.0, min(IDLE_GAP_S, now - self.last)))
+        self.last = now
+        standing = _num(standing_w)
+        if not may_learn or standing is None or abs(standing) > IDLE_ASK_W:
+            self.quiet_since = None
+            return False
+        if self.quiet_since is None:
+            self.quiet_since = now
+        b = _num(reading)
+        if (now - self.quiet_since < IDLE_QUIET_S or b is None
+                or abs(b) > IDLE_SAMPLE_W or dt <= 0.0):
+            return False
+        if self.value is None:
+            self.acc_w += b * dt
+            self.acc_s += dt
+            if self.acc_s < IDLE_FIRST_S:
+                return False
+            self.value = self.acc_w / self.acc_s
+        else:
+            self.value += (b - self.value) * min(1.0, dt / IDLE_TAU_S)
+        if self.saved is None or abs(self.value - self.saved) >= IDLE_SAVE_W:
+            self.saved = self.value
+            return True
+        return False
@@ -127,6 +127,7 @@ from . import messages
 # SAFETY-37. The freshness policy, and the ONE place its bounds are written.
 # freshness.py imports nothing from this package, so the direction is one-way.
 from .freshness import BOUNDS, Freshness
+from .idle import IdleReading
 # CFG-03's ONE in-code mirror of config.yaml's SAFETY-24 defaults. Imported
 # rather than retyped: the flat-keys path below needs `bms_soc_floor`'s
 # shipped default and a literal here would be the fourth defaults site that
@@ -321,13 +322,21 @@ class Inverter:
        # take, 0 none), when that refusal or its last probe started, the
        # current probe's start, and the cycles of evidence so far and when
        # they began. Memory only, like SAFETY-52's: stop and start end it.
-        # Used at N>1 only.
+        # The evidence count is also used at N=1 (SAFETY-94); the rest at N>1.
        self.refused = 0
        self.refused_at = None
        self.probe_from = None
        self.ref_count = 0
        self.ref_since = None
        self.ref_sign = 0
+        self.ref_from = None
+        # SAFETY-97: what this unit's reading shows at idle; "gives nothing"
+        # is centred on it. Learned, persisted, restored (app/idle.py).
+        self.idle = IdleReading(data.get(self.key("idle_w")))
+
+    @property
+    def idle_w(self) -> float:
+        return self.idle.w

    # -- store ---------------------------------------------------------------
    def key(self, name: str) -> str:
@@ -75,8 +75,8 @@ from .hass import HomeAssistant
 from .inverter import (LINK_STALE_S, UNIT_A, build_roster,
                       roster_entries, roster_names)
 from .maintenance import (
-    DRAIN, HOLD, IDLE, POWER_MOVING, MaintConfig, Maintenance, MaintResult,
-    arbitrate as maint_arbitrate,
+    CHARGE, DRAIN, HOLD, IDLE, POWER_MOVING, MaintConfig, Maintenance,
+    MaintResult, arbitrate as maint_arbitrate,
 )
 from .mqtt import (MODE_CONFIGS_KEY, MODE_LABELS, USE_OFF, USE_ON,
                   MqttPublisher, announced_units, mode_configs,
@@ -91,7 +91,7 @@ from .price import required_spread as price_required_spread
 from .price import uncertainty_of as price_uncertainty_of
 from .price_history import PriceHistory
 from .static_tariff import resolve_tariff, static_status
-from .tariff import PeakStore, PeakTracker
+from .tariff import PeakStore, PeakTracker, next_quarter
 from .store import migrate_maint_keys, migrate_unit_keys
 from .validate import (FIRMWARE_INGEST_VETO_S, ConfigRefused, refuse,
                       validate_startup_config, validate_unit_ranges)
@@ -281,6 +281,14 @@ def pack_energy_of(inv):
 # ordinary load steps. At 2 s and slower this changes nothing.
 REFUSED_SPAN_S = (_ctl.SETTLE_CYCLES - 1) * _ctl.LOOP_TICK_S

+# SAFETY-94: the evidence restarts when the reading has moved this far towards
+# the ask since the evidence began. A refusing battery reads flat (-4 W live,
+# 2026-09-06); live readings wander by under 25 W at rest (B's standby, -95 to
+# -118 W, 2026-10-03). A battery crossing the 100 W band on a first-order lag
+# gains 50 W in at most tau x ln(151/101) = 0.4 tau, so the evidence cannot
+# span REFUSED_SPAN_S unless the lag is over 54 s.
+REFUSED_PROGRESS_W = _ctl.PROBE_ANSWER_W / 2
+
 # SAFETY-85 review: a battery another owner set is graded against the least it
 # was told over the same span as above (the plant's measured settle time), so
 # a healthy battery still settling on a new command is not short.
@@ -992,6 +1000,12 @@ class Controller:
        # SAFETY-78: names of draining packs that cannot give power now, so
        # the "waits" line is logged once, not every cycle.
        self._drain_waits = set()
+        # SAFETY-91: last cycle's held-back batteries (`_held_back()`).
+        self._held_was = frozenset()
+        # SAFETY-93: the batteries placed in their maintenance charge last
+        # cycle, and those whose charge ended since the loop last ran.
+        self._charging_was = frozenset()
+        self._charge_ended = frozenset()
        # Set by amain() once the transport is built, so the status page can show
        # what only the transport knows (homewizard_local's unchanged_s). Stays
        # None when P1 is off, or under a transport that has no such counter.
@@ -1235,7 +1249,8 @@ class Controller:
                                     f"gave {batt_w:+.0f} W for "
                                     f"{decision.sat_count} cycles")
        elif self.batt_refused and not now:
-            gave = self.batt_refused * batt_w >= _ctl.PROBE_ANSWER_W
+            gave = (self.batt_refused * (batt_w - self._site_idle_w())
+                    >= _ctl.PROBE_ANSWER_W)
            self._refusal_end("the probe was answered" if gave and probe
                              else "the battery gives power" if gave
                              else "the grid now asks the other direction")
@@ -1253,7 +1268,8 @@ class Controller:
            if ((self.auto or self.shadow) and not inv.refused
                    and inv.ref_count >= t.saturation_cycles
                    and inv.batt_fresh.held is not None
-                    and abs(inv.batt_fresh.held) < _ctl.REFUSED_BELOW_W
+                    and abs(inv.batt_fresh.held - inv.idle_w)
+                    < _ctl.REFUSED_BELOW_W
                    and abs(standing) > _ctl.PROBE_W):
                self._now_mono = now_mono
                self._unit_refusal_start(
@@ -1265,7 +1281,8 @@ class Controller:
                and not self.batt_refused
                and self.sat_count >= t.saturation_cycles
                and inv.batt_fresh.held is not None
-                and abs(inv.batt_fresh.held) < _ctl.REFUSED_BELOW_W
+                and abs(inv.batt_fresh.held - inv.idle_w)
+                < _ctl.REFUSED_BELOW_W
                and abs(standing) > t.saturation_w):
            self._now_mono = now_mono
            self._refusal_start(1 if standing > 0 else -1,
@@ -1338,7 +1355,9 @@ class Controller:
        for inv in self.inverters:
            b = inv.batt
            if inv.refused:
-                if b is not None and inv.refused * b >= _ctl.PROBE_ANSWER_W:
+                # SAFETY-97: given and taken are counted from the idle reading.
+                if (b is not None and inv.refused * (b - inv.idle_w)
+                        >= _ctl.PROBE_ANSWER_W):
                    self._unit_refusal_end(
                        inv, "the probe was answered"
                        if inv.probe_from is not None
@@ -1349,32 +1368,54 @@ class Controller:
                # on its own reading, so one cycle of the loop overshooting
                # through zero does not hand it its share back.
                inv.ref_count = (inv.ref_count + 1 if b is not None and
-                                 -inv.refused * b >= _ctl.PROBE_ANSWER_W else 0)
+                                 -inv.refused * (b - inv.idle_w)
+                                 >= _ctl.PROBE_ANSWER_W else 0)
                if inv.ref_count >= _ctl.SETTLE_CYCLES:
                    self._unit_refusal_end(
                        inv, "the battery takes power the other way")
                continue
-            if b is None:
-                continue        # a gap keeps the count: the gate's trip seeds
-            standing = inv.standing_w()
-            sign = 1 if standing > 0 else -1
-            # One direction throughout: a command that swaps sign every cycle
-            # (a flapping load) reads ~0 through the plant's own lag, and that
-            # is a battery following, not refusing (TEST-19 flapping family).
-            if abs(standing) > _ctl.PROBE_W and abs(b) < _ctl.REFUSED_BELOW_W:
-                if sign != inv.ref_sign or not inv.ref_count:
-                    inv.ref_count, inv.ref_since = 0, self._now_mono
-                inv.ref_count = min(inv.ref_count + 1, _ctl.SETTLE_CYCLES)
-            else:
-                inv.ref_count = 0
-            inv.ref_sign = sign
-            if inv.ref_count >= _ctl.SETTLE_CYCLES and (
-                    inv.ref_since is None or self._now_mono is None
-                    or self._now_mono - inv.ref_since >= REFUSED_SPAN_S):
+            sign = self._gave_nothing(inv)
+            if sign:
                self._unit_refusal_start(
                    inv, sign,
-                    f"asked {standing:+.0f} W, the battery gave {b:+.0f} W "
-                    f"for {_ctl.SETTLE_CYCLES} cycles")
+                    f"asked {inv.standing_w():+.0f} W, the battery gave "
+                    f"{b:+.0f} W for {_ctl.SETTLE_CYCLES} cycles")
+
+    def _gave_nothing(self, inv) -> int:
+        """The refusal evidence, one cycle of it: the sign `inv` has given
+        under REFUSED_BELOW_W while asked over PROBE_W, one way, for
+        SETTLE_CYCLES spanning REFUSED_SPAN_S, else 0. SAFETY-73 at N>1;
+        SAFETY-94 adds it to the N=1 engage in compute(). SAFETY-97: the band
+        is centred on the unit's idle reading."""
+        b = inv.batt
+        if b is None:
+            return 0            # a gap keeps the count: the gate's trip seeds
+        standing = inv.standing_w()
+        sign = 1 if standing > 0 else -1
+        # One direction throughout: a command that swaps sign every cycle
+        # (a flapping load) reads ~0 through the plant's own lag, and that
+        # is a battery following, not refusing (TEST-19 flapping family).
+        if (abs(standing) > _ctl.PROBE_W
+                and abs(b - inv.idle_w) < _ctl.REFUSED_BELOW_W):
+            # SAFETY-94: a reading still moving towards the ask is a battery
+            # catching up through its lag, not one refusing: start again.
+            if (sign != inv.ref_sign or not inv.ref_count
+                    or sign * (b - inv.ref_from) >= REFUSED_PROGRESS_W):
+                inv.ref_count, inv.ref_since, inv.ref_from = (
+                    0, self._now_mono, b)
+            inv.ref_count = min(inv.ref_count + 1, _ctl.SETTLE_CYCLES)
+        else:
+            inv.ref_count = 0
+        inv.ref_sign = sign
+        if inv.ref_count >= _ctl.SETTLE_CYCLES and (
+                inv.ref_since is None or self._now_mono is None
+                or self._now_mono - inv.ref_since >= REFUSED_SPAN_S):
+            return sign
+        return 0
+
+    def _site_idle_w(self) -> float:
+        """SAFETY-97: the site reading at idle, the sum of the units'."""
+        return float(sum(inv.idle_w for inv in self.inverters))

    def _site_refused(self):
        """Owner decision 4: every unit refuses the same way, so the site law
@@ -2366,6 +2407,39 @@ class Controller:
        self.target = want
        self.i_w = want - self.tuning.gain * (want - float(batt))

+    def _charge_track(self, claims, maint_results) -> None:
+        """SAFETY-93, N>=2: a charge ends when its battery leaves CHARGE or can
+        no longer be placed (stale link, refusal). Kept until the loop runs."""
+        if len(self.inverters) < 2:
+            return
+        live = set(self.live_units())
+        now = set()
+        for inv, res in zip(self.inverters, maint_results):
+            u = self.actuator_of("maintenance", inv)
+            if res.phase == CHARGE and u in live and not pre_resolve(
+                    [c for c in claims if c.actuator == u]).contradiction:
+                now.add(inv.name)
+        self._charge_ended |= self._charging_was - now
+        self._charging_was = frozenset(now)
+
+    def _reseed_charge_end(self, maint_results) -> None:
+        """SAFETY-93, N>=2: when a battery's maintenance charge ends, the loop
+        starts from what the others stood at plus that battery's new command
+        (its HOLD pin, or its last discharge if it is free; a charge stops).
+        Else the charge's watts stay in the site target and land on the
+        others: B 0 -> -1600 W in one cycle. DECISIONS/SAFETY-93-charge-end.md.
+        """
+        ended, self._charge_ended = self._charge_ended, frozenset()
+        if len(self.inverters) < 2 or not ended:
+            return
+        for inv, res in zip(self.inverters, maint_results):
+            if inv.name not in ended:
+                continue
+            now_w = (float(res.setpoint_w or 0.0) if res.owns_setpoint
+                     else max(float(inv.target), 0.0))
+            self.target += now_w - float(inv.target)
+        self.i_w = self.target
+
    def _mode_fault_log(self, resolution) -> None:
        """OPT-11: say once, per battery, that its mode was dropped as a fault.

@@ -2567,6 +2641,58 @@ class Controller:
            return frozenset()
        return frozenset(g.held)

+    def _held_back(self) -> frozenset:
+        """SAFETY-91, N>=2: the batteries at or under their own peak reserve
+        while another can still give (live, not refusing). They weigh 0 in
+        every split where the site gives, so they give last (SAFETY-25
+        option A: still drawn once the others are full). One held back
+        stays so until its SoC reads more than 1 point above its reserve, so
+        a reading flipping across it does not swap the split each cycle."""
+        if len(self.inverters) < 2:
+            return frozenset()
+        floor = float(self.o.get(
+            "peak_soc_floor", peakguard.PEAK_OPTION_DEFAULTS["peak_soc_floor"]))
+        ok, held = peakguard.reserve_split(self.packs, floor)
+        held = set(held) | {
+            p.name for p in ok if p.name in self._held_was
+            and float(p.soc) <= peakguard.pack_floor_pct(p, floor) + 1.0}
+        live = set(self.live_units())
+        if not held or not any(
+                p.name not in held and inv.name in live
+                and not (inv.refused or 0) > 0
+                for p, inv in zip(self.packs, self.inverters)):
+            self._held_was = frozenset()
+        else:
+            self._held_was = frozenset(held)
+        return self._held_was
+
+    def _drain_rise(self, claims, maint_results) -> None:
+        """SAFETY-91, N>=2: while a battery is held back (`_held_back()`), a
+        draining battery's pin becomes a floor at its drain rate, so it rises
+        towards its rating before the held one gives. A site stop still
+        decides alone. DECISIONS/SAFETY-91-held-battery-last.md."""
+        held = self._held_back()
+        if not held or any(c.kind == SET and c.actuator == ACTUATOR_SITE
+                           and c.priority > P_PEAK for c in claims):
+            return
+        live = set(self.live_units())
+        for inv, res in zip(self.inverters, maint_results):
+            u = self.actuator_of("maintenance", inv)
+            if res.phase != DRAIN or not res.owns_setpoint \
+                    or inv.name in held or u not in live:
+                continue
+            b = pre_resolve([c for c in claims if c.actuator == u])
+            p = (None if b.contradiction or b.pinned_by != "maintenance"
+                 else allocator.pin_w(b))
+            if p is None or not p > 0.0:
+                continue
+            for i, c in enumerate(claims):
+                if c.source == "maintenance" and c.kind == SET \
+                        and c.actuator == u:
+                    claims[i] = Claim.limit("maintenance", P_MAINTENANCE,
+                                            lo=p, reason=c.reason,
+                                            actuator=u)
+
    def _peak_over_drain(self, claims, maint_results) -> None:
        """SAFETY-83: at N=1 a peak floor above the drain rate outranks it.

@@ -3029,6 +3155,14 @@ class Controller:
        # `stale_input_s` and then commands 0 W and keeps commanding, which is
        # §11.1 rule 1 and is already what a missing reading does here.
        inv.batt = inv.batt_fresh.reading()
+        # SAFETY-97: learn this unit's idle reading, only while control runs
+        # and nothing says the unit is refusing, stale or faulty.
+        if inv.idle.observe(
+                inv.batt, inv.standing_w(), now_mono,
+                bool(self.auto) and inv.batt is not None
+                and not inv.batt_fresh.stale and not inv.refused
+                and not self.batt_refused and not inv.sign_wd.tripped):
+            inv.store_set("idle_w", round(inv.idle.value, 1))
        if inv.batt_fresh.stale and not was_stale:
            self.log_event(f"STALE {inv.name}: " + inv.batt_fresh.reason,
                           hint=messages.hint("battery_stuck", unit=inv.name))
@@ -3071,8 +3205,9 @@ class Controller:
                       inv.batt_fresh.bound.move_w,
                       messages.reason_code(inv.batt_fresh.reason))
            _LOG.debug("Evidence for %s: %s.", inv.name, inv.batt_fresh.reason)
-            _LOG.debug("%s: the limits are unchanged over %.0f s, a command "
-                       "over %.0f W and a move by over %.0f W.", inv.name,
+            _LOG.debug("%s: the limits are unchanged for %.0f s while asked "
+                       "to move: a command over %.0f W that moved over %.0f W.",
+                       inv.name,
                       inv.batt_fresh.bound.unchanged_s,
                       inv.batt_fresh.bound.move_w,
                       inv.batt_fresh.bound.move_w)
@@ -3789,7 +3924,8 @@ class Controller:
                    parked=inv.sign_wd.tripped or bool(inv.refused) or (
                        n_units > 1 and inv.batt is not None
                        and abs(float(standing[inv.name])) <= _ctl.PROBE_W
-                        and abs(float(inv.batt)) < _ctl.REFUSED_BELOW_W),
+                        and abs(float(inv.batt) - inv.idle_w)
+                        < _ctl.REFUSED_BELOW_W),
                    # ⚠️ THIS UNIT'S OWN CUT-OUT. Not the shipped 10 %, and not
                    # the site's `peak_soc_floor` either - that one bounds a
                    # money-saving discharge only, and grading a pack against it
@@ -4082,6 +4218,11 @@ class Controller:
        # gives for SAFETY-18 on a transport that cannot see `unchanged_s`.
        self._peak_proj = (None if not self.p1_enabled
                           else self.peak.project(self.p1.averager, now))
+        # SAFETY-91: at N>=2 the quarter's edge is graded on the next quarter,
+        # so a HOLD's ceiling does not lapse for a cycle onto a held battery.
+        if self._peak_proj is not None and len(self.inverters) > 1:
+            self._peak_proj = next_quarter(self._peak_proj,
+                                           self.p1.averager.max_hold_s)
        self.peak_guard = None if not self.p1_enabled else peakguard.decide(
            self._peak_proj,
            # ⚠️ THE SITE SUM. The guard sizes a floor from what the battery is
@@ -4482,6 +4623,8 @@ class Controller:
            claims.append(Claim.limit("hold", P_MAINTENANCE, hi=hold_hi,
                                      reason="maintenance hold",
                                      actuator=self.actuator_of("hold")))
+        # --- SAFETY-91: a drain rises before a held battery gives ------------
+        self._drain_rise(claims, maint_results)
        # --- SAFETY-84: a cheap-window charge is a ceiling over the site ----
        charge = self._charge_ceiling(claims)
        if charge is not None:
@@ -4495,6 +4638,7 @@ class Controller:
        if self.modes_on:
            mode_trade = self._mode_trade(claims, now)
        self._mode_trade_was = mode_trade
+        self._charge_track(claims, maint_results)
        if (self.auto or self.shadow) and self.inputs_ok:
            # ⚠️ prev is the ARBITER's last output, not the loop's own last
            # wish. If something outranked the loop, that is what the hardware
@@ -4521,6 +4665,8 @@ class Controller:
            # is what seeds it, and dropping it there restarts the ~70 s cycle.
            if self.loop_w is not None and self.target != self.loop_w:
                self._refusal_end("another writer")
+            # SAFETY-93: a charge that ended leaves the loop's start point.
+            self._reseed_charge_end(maint_results)
            probe = self._refusal_probe()
            if len(self.inverters) > 1:
                probe = any(_probing.values())
@@ -4559,6 +4705,12 @@ class Controller:
                refused=self.batt_refused if len(self.inverters) == 1
                else self._site_refused(),
                probe=probe,
+                # SAFETY-94: at N=1 the engage also needs the reading to have
+                # given nothing for the whole span, as at N>1.
+                gave_nothing=(bool(self._gave_nothing(self.inverters[0]))
+                              if len(self.inverters) == 1 else None),
+                # SAFETY-97: "gives nothing" is centred on the idle reading.
+                idle_w=self._site_idle_w(),
                # OPT-11: None unless battery modes are on. SAFETY-85: or while
                # maintenance holds a battery at N>=2, so the loop does not
                # wind past what the others can give and jump when it ends.
@@ -4680,7 +4832,7 @@ class Controller:
        while True:
            resolution = resolve(claims, units=self.units, live=_live,
                                 weights=self.pack_weights, tick=self.alloc_tick,
-                                 reserve=self._peak_reserve())
+                                 reserve=self._held_back())
            # SAFETY-73: a probe pin stands only while the resolved site target
            # asks at least PROBE_W its way. Below that a sibling would carry
            # the opposite direction (circulation), so the pin goes back to the
@@ -822,6 +822,22 @@ class PeakTracker:
            held_w=averager.held_net_w)


+def next_quarter(p: Projection, max_hold_s: float) -> Projection:
+    """SAFETY-91: `p` past its block's end, before the next block's first
+    telegram: the next quarter, projected from the held reading (the averager
+    credits it there). `p` itself otherwise, or when that reading is too old
+    to be credited. DECISIONS/SAFETY-91-held-battery-last.md."""
+    if p.block_start is None or p.elapsed_s < QUARTER_S \
+            or p.elapsed_s * (1.0 - p.covered_frac) > float(max_hold_s):
+        return p
+    held = max(p.held_w, 0.0)
+    return Projection(projected_w=held, elapsed_w=held,
+                      elapsed_s=p.elapsed_s - QUARTER_S, covered_frac=1.0,
+                      complete=True,
+                      block_start=p.block_start + timedelta(seconds=QUARTER_S),
+                      held_w=p.held_w)
+
+
@dataclass(frozen=True)
 class _ClosedBlock:
    """A block reconstructed from a checkpoint. Shaped like `p1.QuarterBlock` so
@@ -1,5 +1,5 @@
 name: GoodWe RS485 Controller
-version: "0.13.0"
+version: "0.15.0"
 slug: goodwe_controller
 description: >-
  Drives a GoodWe ES/BP battery inverter over RS485 by emulating its smart
@@ -439,7 +439,7 @@ class _Hass:
        return True


-def wired(grid, cycles=40, batt=0.0, track=True, **over):
+def wired(grid, cycles=40, batt=0.0, track=True, tick=None, **over):
    async def go():
        hass = _Hass(grid, batt=batt, track=track)
        c = Controller(dict(
@@ -455,8 +455,11 @@ def wired(grid, cycles=40, batt=0.0, track=True, **over):
        # hysteresis clears it a few cycles later - so it is captured live
        # rather than looked for after the run, when it is correctly gone.
        c.red_snapshot = []
-        for _ in range(cycles):
-            await c.read_inputs()
+        for i in range(cycles):
+            # `tick`: simulated seconds per cycle. SAFETY-94: a refusal needs
+            # its evidence to span REFUSED_SPAN_S, which back-to-back cycles
+            # on the real clock never do.
+            await c.read_inputs(now_mono=None if tick is None else i * tick)
            await c.cycle()
            if c.clamp_wd.active and not c.red_snapshot:
                c.red_snapshot = c.checks()
@@ -474,7 +477,7 @@ def clamp_notes(hass):
 # unclamped integrator climbed ~130 W per 4 s to over 10 kW and, pinned at the
 # 5 kW rail, reported 14 768 W." `track=False` is the inverter switched off: it
 # reports 0 W however hard it is commanded, so the error never closes.
-hass_r, ctl_r = wired(6000.0, cycles=60, track=False)
+hass_r, ctl_r = wired(6000.0, cycles=60, track=False, tick=2.0)
 emitted = [abs(w) for w in hass_r.writes]

 # What the SAME error would have done to an accumulator with no bound - the
@@ -900,34 +900,51 @@ def _loop_series(day, sig):
    return out


+class _Before94(Freshness):
+    """The gate before SAFETY-94: the clock ran from the register's last
+    change, not from when the command asked it to move. The history below is
+    about that gate, so it is replayed on it."""
+
+    def obliged_s(self):
+        return self.graded_s(self.last_read)
+
+
+def _replay16(cls):
+    """Every committed day at 1 Hz. Returns (trips, waits for the next move)."""
+    waits, trips = [], 0
+    for _day in _loop_days:
+        _b, _s = _loop_series(_day, "batt"), _loop_series(_day, "setpoint")
+        if not _b or not _s:
+            continue
+        _moves = [r[0] for i, r in enumerate(_b)
+                  if i == 0 or r[1] != _b[i - 1][1]]
+        _f8b, _prev8b = cls(BOUNDS["batt"]), False
+        _ib = _is = 0
+        _t = max(_b[0][0], _s[0][0])
+        _end = min(_b[-1][0], _s[-1][0])
+        while _t <= _end:
+            while _ib + 1 < len(_b) and _b[_ib + 1][0] <= _t:
+                _ib += 1
+            while _is + 1 < len(_s) and _s[_is + 1][0] <= _t:
+                _is += 1
+            _f8b.submit(_b[_ib][1], _s[_is][1], _t)
+            if _f8b.stale and not _prev8b:
+                trips += 1
+                _nxt = next((m for m in _moves if m > _t), None)
+                if _nxt is not None:
+                    waits.append(_nxt - _t)
+            _prev8b = _f8b.stale
+            _t += 1.0
+    return trips, sorted(waits)
+
+
 _t8b = time.monotonic()
-_waits, _trips8b = [], 0
-for _day in _loop_days:
-    _b, _s = _loop_series(_day, "batt"), _loop_series(_day, "setpoint")
-    if not _b or not _s:
-        continue
-    _moves = [r[0] for i, r in enumerate(_b) if i == 0 or r[1] != _b[i - 1][1]]
-    _f8b, _prev8b = Freshness(BOUNDS["batt"]), False
-    _ib = _is = 0
-    _t = max(_b[0][0], _s[0][0])
-    _end = min(_b[-1][0], _s[-1][0])
-    while _t <= _end:
-        while _ib + 1 < len(_b) and _b[_ib + 1][0] <= _t:
-            _ib += 1
-        while _is + 1 < len(_s) and _s[_is + 1][0] <= _t:
-            _is += 1
-        _f8b.submit(_b[_ib][1], _s[_is][1], _t)
-        if _f8b.stale and not _prev8b:
-            _trips8b += 1
-            _nxt = next((m for m in _moves if m > _t), None)
-            if _nxt is not None:
-                _waits.append(_nxt - _t)
-        _prev8b = _f8b.stale
-        _t += 1.0
-_waits.sort()
+_trips8b, _waits = _replay16(_Before94)
+_trips94, _waits94 = _replay16(Freshness)
 _p50 = nth(_waits, len(_waits) // 2)
 print(f"    {len(_loop_days)} days replayed at 1 Hz in "
-      f"{time.monotonic() - _t8b:.1f}s: {_trips8b} trips")
+      f"{time.monotonic() - _t8b:.1f}s (twice): {_trips8b} trips before "
+      f"SAFETY-94, {_trips94} after")
 print(f"    wait for the register's next change after a trip: "
      f"min {nth(_waits, 0):.1f} s  median {_p50:.1f} s  max {nth(_waits, -1):.1f} s; "
      f"{sum(1 for w in _waits if w >= 710.0)} at or over the live episode's "
@@ -953,6 +970,17 @@ check("⚠️ AND THAT DISTRIBUTION IS A PROPERTY OF THIS BMS, NOT OF THIS CODE
      "is `stale_input_s + release_s` = 32 s whatever the register does",
      sum(1 for w in _waits if w < 20.0) >= 20
      and float(option_default("stale_input_s")) + BOUNDS["batt"].release_s == 32.0)
+print(f"    SAFETY-94: trips answered within 20 s: {sum(1 for w in _waits if w < 20.0)}"
+      f" before, {sum(1 for w in _waits94 if w < 20.0)} after; quickest "
+      f"answer after a trip {nth(_waits94, 0):.1f} s")
+check("⚠️ SAFETY-94 (SAFETY-58): MOST OF THOSE SHORT WAITS WERE FALSE TRIPS, "
+      "NOT KEEP-ALIVE PULSES. The clock now counts only the time the command "
+      "asked the register to move. The same sixteen days give 59 trips, not "
+      "93, and only one of the 59 is answered within 20 s (21 before): the "
+      "gate no longer judges a register on the first read after a rest",
+      _trips94 == 59 and len(_waits94) == _trips94
+      and sum(1 for w in _waits94 if w < 20.0) == 1
+      and sum(1 for w in _waits if w < 20.0) == 21)


 # ==============================================================================
@@ -1017,32 +1045,30 @@ check("NOT A SURVIVOR, recorded because it looks like one: a publisher failure "
      "each unit's own command travel and each unit's own number",
      _s4a.stale and _s4b.stale and _s4a.held != _s4b.held)

-# S5. SAFETY-57's own, and it is a FALSE POSITIVE that predates this card.
-#     The unchanged clock keeps running while the site rests, so the FIRST read
-#     at which a command travels 250 W after a long quiet already satisfies all
-#     three terms - the register is given no time at all to answer the new
-#     command. Present on the shipped tree; the live capture in part 10 contains
-#     one (10:48:14, cleared one second later).
+# S5. SAFETY-57's own FALSE POSITIVE, CLOSED BY SAFETY-94 (it was SAFETY-58).
+#     The unchanged clock used to keep running while the site rested, so the
+#     FIRST read at which a command travelled 250 W after a long quiet tripped
+#     the gate. The clock now counts only time the register was asked to move.
+#     Live 2026-10-03: four such trips, each 1 s after the command.
 _s5 = Freshness(BOUNDS["batt"])
 for t in range(0, 300):                     # five minutes of a resting site
    _s5.submit(-3.0, 0.0, float(t))
 _s5_quiet = _s5.stale
 _s5.submit(-3.0, 1500.0, 300.0)             # the loop asks for 1500 W
-check("⚠️ SURVIVOR 5, FALSE POSITIVE, AND IT IS OLDER THAN SAFETY-57: after a "
-      "long rest the unchanged clock is already past 35 s, so the very FIRST "
-      "read carrying a travelled command trips the gate - before the 17.0 s in "
-      "which a healthy register could have answered it. The gate accuses on "
-      "read one and the register answers on read eleven",
-      not _s5_quiet and _s5.stale and _s5.graded_s(300.0) == 300.0)
-check("...and its SIZE is one `stale_input_s` hold, which is why it is recorded "
-      "here rather than fixed here: `cycle()` returns at `inputs missing "
-      "{n}s` for the whole of it, so nothing is commanded differently, and the "
-      "register's next publish clears it. Fixing it means measuring the "
-      "unchanged clock from when the OBLIGATION appeared rather than from the "
-      "register's last move, which re-derives the 35.0 s bound and is a "
-      "different card",
-      (lambda f: (f.submit(-4.0, 1500.0, 311.0), not f.stale)[-1])(_s5)
-      and float(option_default("stale_input_s")) >= 5.0)
+_s5_first = _s5.stale
+for t in range(301, 334):
+    _s5.submit(-3.0, 1500.0, float(t))
+_s5_before = _s5.stale
+_s5.submit(-3.0, 1500.0, 334.0)
+check("⚠️ SURVIVOR 5 IS CLOSED (SAFETY-94): after five minutes of rest the "
+      "first read carrying a travelled command is NOT a trip, nor is any read "
+      "before 35 s of standing command - and a register that still has not "
+      "moved after 35 s of it IS",
+      not _s5_quiet and not _s5_first and not _s5_before and _s5.stale
+      and _s5.graded_s(334.0) == 334.0 and _s5.obliged_s() == 35.0)
+check("...and the evidence sentence still gives the register's own unchanged "
+      "time (334 s), which an operator compares with a history graph",
+      "unchanged for 334 s" in _s5.reason)


 # ==============================================================================
@@ -1353,20 +1379,23 @@ print(f"      after  : held number reached a consumer on {sum(_exp57)} reads "

 check("⚠️ THE EXIT IS NOT FREE AND THE PRICE IS STATED AS A NUMBER. A register "
      "that is dead for good is re-graded for ever: over 1201 reads the held "
-      "number reaches a consumer on 630 of them against 35 before, and 17 "
+      "number reaches a consumer on 631 of them against 36 before, and 17 "
      "releases are taken. This check exists so that cost cannot be quietly "
      "forgotten, and so a change that makes it worse has to move a number "
      "somebody reads",
-      sum(_expb) == 35 and sum(_exp57) == 630 and _dead.releases == 17
+      sum(_expb) == 36 and sum(_exp57) == 631 and _dead.releases == 17
      and _deadb.releases == 0)
 check("⚠️ AND IT IS PAYABLE ONLY BECAUSE ONE RUN IS SHORTER THAN EITHER "
-      "CONSUMER'S HOLD. Every unbroken run of exposure is exactly one 35.0 s "
-      "grading window, and 35 < 75 (circulation_hold_s) < 85 "
+      "CONSUMER'S HOLD. Every unbroken run of exposure after a release is "
+      "exactly one 35.0 s window of standing command (the first is 36 s: the "
+      "fixture's command starts one read late), and 36 < 75 "
+      "(circulation_hold_s) < 85 "
      "(unit_sign_disagree_s) - so NEITHER detector can reach a verdict inside "
      "one, and the re-trip that ends each run hands them a None, which CLEARS "
      "their windows rather than accumulating into them",
-      set(_runs57) == {BOUNDS["batt"].unchanged_s}
-      and BOUNDS["batt"].unchanged_s < _circ_hold < _unit_hold)
+      set(_runs57[1:]) == {BOUNDS["batt"].unchanged_s}
+      and nth(_runs57, 0) == BOUNDS["batt"].unchanged_s + 1.0
+      and max(_runs57) < _circ_hold < _unit_hold)
 check("...and nothing SAFETY-37 detects is given back by that, which is the "
      "half that makes the trade a trade. A permanent None clears both windows "
      "for ever too, so on the shipped-before module the same two detectors are "
@@ -1643,8 +1672,10 @@ check("...and a re-trip's reason names the TWO durations separately, each "
          [f.submit(A_FROZEN_W, 0.0, float(t)) for t in range(40, 80)],
          [f.submit(A_FROZEN_W, 1300.0, float(t)) for t in range(80, 130)],
          f.stale and f.releases == 1
-          and "unchanged for 92 s" in f.reason
-          and "checked 2 times over a 35 s window since the last stop was "
+          # SAFETY-94: the re-trip comes 35 s after the command returns at
+          # 80 s (114 s), not 35 s after the release at 57 s.
+          and "unchanged for 114 s" in f.reason
+          and "checked 2 times over a 57 s window since the last stop was "
              "withdrawn" in f.reason)[-1])(
              Freshness(BOUNDS["batt"])))

@@ -129,6 +129,19 @@ finally:
 # cd4d9cb5b7e29ff4ab4fe65dab5106683d8a599f09323fbdee4018ad9b28fcd1.
 SAFETY78_N2_MAINT = \
    "1afcd46b1b987868b110d2b0f4a7555848c9aa4728a836d4a2ce2a2107268497"
+# SAFETY-91 changes n2 and n2_off ON PURPOSE: from t=1600 battery A is at its
+# 20 % reserve, so B carries the house first and A gives last. With
+# `_held_back()` reverted to SAFETY-87's (held only for the peak) both are
+# a5dddad's again, which the check below grades.
+SAFETY91_N2 = \
+    "9535c08f556d6d50bec8fb0872445173480c29b10df1a7c437ef73d6ddb2814d"
+_real_hb = app_main.Controller._held_back
+app_main.Controller._held_back = lambda self: self._peak_reserve()
+try:
+    _n2_s87 = rig.digest(rig.run(**rig.SCENARIOS["n2"])[0])
+finally:
+    app_main.Controller._held_back = _real_hb
+_S91 = ("n2", "n2_off", "n2_maint")
 for k in A5DDDAD:
    print(f"    {k:7} {'same' if _now[k] == A5DDDAD[k] else 'DIFFERS'} "
          f"{_now[k][:16]}")
@@ -136,10 +149,20 @@ check("⭐ at N=1 and N=2, with the option absent and with it false, every "
      "command, reason and allocation record over 540 cycles each is "
      "byte-identical to a5dddad (house steps, a solar surplus, a battery "
      "at its cut-out level, at N=2 a refusal with probes, both batteries "
-      "due for maintenance; n2_maint apart, below), and so is the arbiter "
-      "on 6000 claim lists",
-      {k: v for k, v in _now.items() if k != "n2_maint"}
-      == {k: v for k, v in A5DDDAD.items() if k != "n2_maint"})
+      "due for maintenance; n2, n2_off and n2_maint apart, below), and so "
+      "is the arbiter on 6000 claim lists",
+      {k: v for k, v in _now.items() if k not in _S91}
+      == {k: v for k, v in A5DDDAD.items() if k not in _S91})
+# SAFETY-94: with SAFETY-87's held rule, A (cut out at 1600 s) now trips the
+# stale gate at 1640 s, not 1635 s - 35 s after its command moved rather than
+# after its reading last changed - so that run is no longer a5dddad's. It was
+# a5dddad's (a60003b1...) before SAFETY-94. The shipped n2 is unchanged.
+SAFETY94_N2_S87 = \
+    "4ddea7ef9dc1efa437af899675db442cd531b084ae4cec35951d7c7bb3d6d8b5"
+check("...n2 and n2_off are the SAFETY-91 digest (A at its reserve gives "
+      "last), and SAFETY-87's held rule gives SAFETY-94's",
+      _now["n2"] == _now["n2_off"] == SAFETY91_N2 != A5DDDAD["n2"]
+      and _n2_s87 == SAFETY94_N2_S87)
 check("...and n2_maint is the SAFETY-78 digest: the N=2 drain that a5dddad "
      "refused on 392 of 540 cycles now runs (test_safety78.py), bounded by "
      "SAFETY-85",
@@ -3132,6 +3132,10 @@ check("...and between them the nineteen appends account for exactly the "
 # through this file's reading of main.py. It grades three of the eight appends.
 # The static pin above is what covers the other five.
 _b2, _restore_b2 = second_inverter(c_src)
+# SAFETY-91: B states a cut-out, as every roster entry must (rule 8). Without
+# one it is held back at its reserve and gives last, so A alone would carry
+# this cycle's 500 W and the broadcast check below could not see a split.
+_b2.bms_soc_floor = c_src.inverters[0].bms_soc_floor
 _n2_writes_before = len(c_src.hass.per_entity)
 try:
    _, _cl2 = cycle_claims(lambda: run_cycle(c_src))
@@ -559,11 +559,14 @@ def _drain_run():

 DR = _drain_run()
 _real_dor = Controller._drain_over_reserve
+_real_rise = Controller._drain_rise     # SAFETY-91 would raise B as well
 Controller._drain_over_reserve = lambda self, claims, results: None
+Controller._drain_rise = lambda self, claims, results: None
 try:
    DR_OLD = _drain_run()
 finally:
    Controller._drain_over_reserve = _real_dor
+    Controller._drain_rise = _real_rise


 def _a_for_peak(rows):
@@ -0,0 +1,452 @@
+"""Runnable check for SAFETY-91: a held battery is drawn only after the others
+are full. `python3 test_safety91.py`
+
+At N>=2 a battery at or under its peak reserve was held back only while the
+peak guard asked for power. The self-consumption loop drew it at its full
+rating while a draining battery stayed at its drain rate (SAFETY-87 rig test
+F1), and at a quarter's edge in a HOLD the held battery gave 2500 W for one
+cycle (F2). Now a held battery weighs 0 whenever the site gives, a draining
+battery rises above its drain rate before it, and the edge is graded on the
+next quarter. SAFETY-25 option A stands: once the others are full the loop
+may still draw it. Drives the REAL Controller on a lagging battery (10 s, as
+on the rig). DECISIONS/SAFETY-91-held-battery-last.md.
+
+1. B draining, A held, house over B's rating: B rises to full before A gives.
+2. A held reaching its cut-out: nothing is placed on it, B gives its rating.
+3. HOLD across a quarter edge: the held battery gives nothing at the edge.
+4. Idle, A held: B carries the house first; both held or B refusing: as before;
+   a SoC reading flipping across the reserve does not swap the split.
+5. The rules at their boundaries (claim lists, N=3, a site stop).
+6. next_quarter() at its boundaries.
+7. N=1 is untouched.
+
+Mutations (MUTATION.md, purged copies) are listed in the pull request.
+"""
+
+import logging
+import math
+import os
+import sys
+import time
+import types
+from datetime import timedelta
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+sys.path.insert(0, os.path.join(HERE, "tools"))
+logging.disable(logging.WARNING)
+
+import opt11_identity as rig                                   # noqa: E402
+import safety84_identity as s84                                # noqa: E402
+from app import peakguard                                      # noqa: E402
+from app.arbiter import (Claim, P_MAINTENANCE, P_SAFETY,        # noqa: E402
+                         resolve)
+from app.main import Controller                                # noqa: E402
+from app.maintenance import DRAIN, HOLD, IDLE, MaintResult     # noqa: E402
+from app.p1 import make_sample, split_signed                   # noqa: E402
+from app.store import unit_key                                 # noqa: E402
+from app.tariff import QUARTER_S, Projection, next_quarter     # noqa: E402
+
+fails = []
+A, B = "inverter-a", "inverter-b"
+FULL = 2500.0
+CUT = 10.0              # bms_soc_floor of both test batteries
+
+
+def check(name, cond):
+    print(f"  {'ok  ' if cond else 'FAIL'} {name}")
+    if not cond:
+        fails.append(name)
+
+
+def lagging(fn, lag=10.0, tick=1.0, lags=None):
+    """`fn` on plantsim's battery (800 W/s ramp, `lag` s first-order lag, or
+    `lags[u]`), a 1 s meter tick, and a BMS that stops discharge at its
+    cut-out."""
+    real_p, real_t = rig._Hass.power, rig.TICK
+
+    def power(self, u):
+        st = self.__dict__.setdefault("_plant", {})
+        a, tgt, tl = st.get(u, (0.0, 0.0, self.t))
+        for _ in range(int(round((self.t - tl) / 0.1))):
+            d = self.cmd[u] - tgt
+            tgt += math.copysign(min(abs(d), 80.0), d)
+            a += (tgt - a) * (1 - math.exp(-0.1 / (lags or {}).get(u, lag)))
+        st[u] = (a, tgt, self.t)
+        return 0.0 if self.soc(u, self.t) <= CUT and a > 0 else float(round(a))
+    rig._Hass.power, rig.TICK = power, tick
+    try:
+        return fn()
+    finally:
+        rig._Hass.power, rig.TICK = real_p, real_t
+
+
+def store(phase_of, n=2):
+    """`phase_of`: {name: phase}; the others have just done their cycle."""
+    s = rig._Store()
+    for u in (A, B)[:n]:
+        key = (lambda k: k) if n == 1 else (lambda k: unit_key(u, k))
+        if u in phase_of:
+            s.data[key("phase")] = phase_of[u]
+            s.data[key("phase_started")] = rig.BASE.isoformat()
+        else:
+            s.data[key("last_completed")] = rig.BASE.isoformat()
+    return s
+
+
+def run(house, phase_of, socs, dur, late=0.0, kwh=15.36, n=2, read=None,
+        lags=None):
+    """Rows and controller. Levels follow each battery's measured power; the
+    P1 telegram read at each cycle is `late` s old. `read(u, t, level)` is
+    the SoC the controller reads (default the level)."""
+    soc, last, levels = dict(socs), [0.0], {}
+    grid = []
+
+    def before(c, t):
+        grid.append((t, c.hass.grid()))
+        for u in soc:
+            soc[u] = max(CUT, soc[u] - c.hass.power(u) * (t - last[0])
+                         / 3600.0 / (kwh * 10.0))
+        last[0], levels[t] = t, dict(soc)
+        imp, exp = split_signed(c.hass.grid())
+        c.p1.submit(make_sample("ha_signed", imp, exp, phases=1,
+                                ingest_ts=rig.BASE + timedelta(seconds=t - late),
+                                ingest_mono=time.monotonic()))
+    rows, c = lagging(lambda: s84.run(
+        n, load=house if callable(house) else (lambda t: house), cheap=False,
+        store=store(phase_of, n), before=before, dur=dur,
+        soc=(lambda u, t: soc[u]) if read is None
+        else (lambda u, t: read(u, t, soc[u])),
+        extra={"maintenance_discharge_w": 1000,
+               "maintenance_hold_min": 600}), lags=lags)
+    c.levels, c.grid = levels, grid
+    return rows, c
+
+
+def without_fix(fn):
+    """release/1.0 8c438ab: held only for the peak, a drain stays pinned, the
+    quarter's edge is not rolled over."""
+    real = (Controller._held_back, Controller._drain_rise)
+    import app.main as m
+    real_nq = m.next_quarter
+    Controller._held_back = lambda self: self._peak_reserve()
+    Controller._drain_rise = lambda self, claims, results: None
+    m.next_quarter = lambda p, max_hold_s: p
+    try:
+        return fn()
+    finally:
+        Controller._held_back, Controller._drain_rise = real
+        m.next_quarter = real_nq
+
+
+def cmd(r):
+    return dict(r[2])
+
+
+def seg(rows, lo, hi):
+    """Mean A and B commands over [lo, hi) s."""
+    rs = [r for r in rows if lo <= r[0] < hi]
+    return (round(sum(cmd(r)["a"] for r in rs) / len(rs)),
+            round(sum(cmd(r)["b"] for r in rs) / len(rs)))
+
+
+def a_before_b(rows, t0=0.0):
+    """Cycles where held A is asked to give while B is not at full power."""
+    return sum(1 for r in rows if r[0] >= t0
+               and cmd(r)["a"] > 0.0 and cmd(r)["b"] < FULL)
+
+
+def unmet(rows, lo, hi):
+    return sum(1 for r in rows if lo <= r[0] < hi and r[7] and "UNMET" in r[7])
+
+
+# ============================================================================ #
+print("1. B draining at 1000 W, A held at 15 %, house over B's rating")
+STEPS = (800.0, 4000.0, 5500.0)
+
+
+def steps(t):
+    return STEPS[min(int(t // 300), 2)]
+
+
+DR = run(steps, {B: DRAIN}, {"a": 15.0, "b": 60.0}, 900.0)
+DR_OLD = without_fix(lambda: run(steps, {B: DRAIN}, {"a": 15.0, "b": 60.0},
+                                 900.0))
+for tag, (rows, c) in (("after", DR), ("before", DR_OLD)):
+    print(f"    {tag}: house 800 A/B {seg(rows, 60, 300)}, 4000 "
+          f"{seg(rows, 360, 600)}, 5500 {seg(rows, 660, 900)}; A asked while "
+          f"B not full: {a_before_b(rows)} cycles; UNMET "
+          f"{unmet(rows, 0, 900)}")
+check("⭐ A (held) is never asked to give while B has room: every cycle that "
+      "puts power on A has B at its full 2500 W",
+      a_before_b(DR[0]) == 0 and DR[1].maints[1].phase == DRAIN)
+check("...house 4000: B rises from its 1000 W drain rate to 2500 W and A "
+      "gives only the 1500 W rest (before: A 2500, B 1000)",
+      seg(DR[0], 360, 600)[1] >= 2480 and seg(DR[0], 360, 600)[0] <= 1520
+      and seg(DR_OLD[0], 360, 600)[0] >= 2480
+      and seg(DR_OLD[0], 360, 600)[1] <= 1020)
+check("...house 800: B still drains at its 1000 W rate (the rest is "
+      "exported, as before) and A gives nothing",
+      all(cmd(r)["b"] >= 1000.0 and cmd(r)["a"] == 0.0
+          for r in DR[0] if 60 <= r[0] < 300))
+check("...house 5500 (over both ratings): option A stands, A is drawn as a "
+      "last resort once B is full, and nothing is left UNMET",
+      seg(DR[0], 660, 900) == (2500, 2500) and unmet(DR[0], 0, 900) == 0)
+check("non-vacuous: before the fix A was asked while B had room",
+      a_before_b(DR_OLD[0]) >= 100)
+
+# ============================================================================ #
+print("\n2. the held battery reaches its cut-out (house 5500)")
+CO = run(5500.0, {B: DRAIN}, {"a": 11.0, "b": 60.0}, 1200.0)
+CO_OLD = without_fix(lambda: run(5500.0, {B: DRAIN}, {"a": 11.0, "b": 60.0},
+                                 1200.0))
+
+
+def after_cut(rows, c):
+    """Rows once A reads its cut-out (its level follows its power)."""
+    return [r for r in rows if c.levels[r[0]]["a"] <= CUT]
+
+
+_ac, _ac_old = after_cut(*CO), after_cut(*CO_OLD)
+print(f"    after A's cut-out: B {seg(_ac, 0, 9e9)[1]} W over {len(_ac)} "
+      f"cycles (before: {seg(_ac_old, 0, 9e9)[1]} W); A soc "
+      f"{CO[1].inverters[0].soc:.2f} %")
+check("⭐ at its cut-out nothing is placed on A (0 W on every cycle), B "
+      "gives its full 2500 W and nothing is left UNMET on the empty A",
+      CO[1].inverters[0].soc <= CUT and len(_ac) >= 100
+      and all(cmd(r)["a"] == 0.0 and cmd(r)["b"] == FULL for r in _ac)
+      and unmet(CO[0], 600, 1200) == 0)
+check("non-vacuous: before the fix B stayed pinned under its rating on most "
+      "of those cycles (the rig saw ~2422 W)",
+      len(_ac_old) >= 100
+      and sum(1 for r in _ac_old if cmd(r)["b"] < FULL) > len(_ac_old) / 2)
+
+# ============================================================================ #
+print("\n3. HOLD across a quarter edge (A full holding, B held at 15 %)")
+EDGE = run(5500.0, {A: HOLD}, {"a": 99.0, "b": 15.0}, 1000.0, late=0.5)
+EDGE_OLD = without_fix(lambda: run(5500.0, {A: HOLD}, {"a": 99.0, "b": 15.0},
+                                   1000.0, late=0.5))
+
+
+def at_edge(rows):
+    return [(r[0], cmd(r)["a"], cmd(r)["b"]) for r in rows
+            if QUARTER_S - 1 <= r[0] <= QUARTER_S + 1]
+
+
+print(f"    edge after {at_edge(EDGE[0])}, before {at_edge(EDGE_OLD[0])}")
+check("⭐ the telegram at the edge comes late (0.5 s): B gives nothing on any "
+      "cycle (the first cycle, before any quarter is measured, aside), A "
+      "keeps giving and stays in its HOLD",
+      all(cmd(r)["b"] == 0.0 for r in EDGE[0] if r[0] > 0)
+      and all(a > 2000.0 for _t, a, _b in at_edge(EDGE[0]))
+      and EDGE[1].maints[0].phase == HOLD)
+check("non-vacuous: before the fix B gave over 2000 W at the edge (F2)",
+      any(b > 2000.0 for _t, _a, b in at_edge(EDGE_OLD[0])))
+
+# ============================================================================ #
+print("\n4. idle, house 2000 W")
+ID = run(2000.0, {}, {"a": 15.0, "b": 60.0}, 300.0)
+ID_OLD = without_fix(lambda: run(2000.0, {}, {"a": 15.0, "b": 60.0}, 300.0))
+print(f"    A held: after {seg(ID[0], 120, 300)}, before "
+      f"{seg(ID_OLD[0], 120, 300)}")
+check("⭐ A held, B able: B carries the house alone; A is asked only on the "
+      "cycles where the lagging B is already at its full command",
+      a_before_b(ID[0]) == 0 and seg(ID[0], 120, 300)[0] == 0
+      and seg(ID[0], 120, 300)[1] >= 1950)
+check("non-vacuous: before the fix the weights gave A a share",
+      seg(ID_OLD[0], 120, 300)[0] > 50)
+BOTH = run(2000.0, {}, {"a": 15.0, "b": 14.0}, 300.0)
+BOTH_OLD = without_fix(lambda: run(2000.0, {}, {"a": 15.0, "b": 14.0}, 300.0))
+check("...both held: nothing to give first, the split is as before",
+      [r[:3] for r in BOTH[0]] == [r[:3] for r in BOTH_OLD[0]])
+
+
+def held_back(socs, refused=(0, 0), live=(A, B)):
+    c = ID[1]
+    for inv, s, r in zip(c.inverters, socs, refused):
+        inv.soc, inv.refused = s, r
+    c.live_units = lambda: live
+    try:
+        return c._held_back()
+    finally:
+        del c.live_units
+        for inv in c.inverters:
+            inv.refused = 0
+
+
+check("...held back only while another can give: A held beside B able; "
+      "nothing with B refusing to give, B dropped, or both under",
+      held_back((15.0, 60.0)) == {A} and held_back((15.0, 60.0), (0, 1))
+      == frozenset() and held_back((15.0, 60.0), live=(A,)) == frozenset()
+      and held_back((15.0, 14.0)) == frozenset()
+      and held_back((15.0, 60.0), (0, -1)) == {A})
+
+# A's SoC READING flips 20/21 % across its 20 % reserve every 10 s, and B
+# follows its command faster (3 s) than A (10 s), as two different inverters.
+def _flip(u, t, level):
+    return (20.0 + int(t // 10) % 2) if u == "a" else level
+
+
+def _a_jumps(rows, t0):
+    rs = [r for r in rows if r[0] >= t0]
+    return sum(1 for p, q in zip(rs, rs[1:])
+               if abs(cmd(p)["a"] - cmd(q)["a"]) > 300.0)
+
+
+def _grid_rms(c, t0):
+    g = [w + 10.0 for t, w in c.grid if t >= t0]
+    return math.sqrt(sum(w * w for w in g) / len(g))
+
+
+_lags = {"a": 10.0, "b": 3.0}
+FL = run(2000.0, {}, {"a": 20.0, "b": 60.0}, 600.0, read=_flip, lags=_lags)
+_real_was = Controller.__dict__["_held_back"]
+
+
+def _no_hyst(self):
+    self._held_was = frozenset()
+    return _real_was(self)
+
+
+Controller._held_back = _no_hyst
+try:
+    FL_OLD = run(2000.0, {}, {"a": 20.0, "b": 60.0}, 600.0, read=_flip,
+                 lags=_lags)
+finally:
+    Controller._held_back = _real_was
+print(f"    A's reading flipping 20/21 %: A jumps {_a_jumps(FL[0], 120)}, "
+      f"grid rms {_grid_rms(FL[1], 120):.0f} W (no hysteresis: "
+      f"{_a_jumps(FL_OLD[0], 120)}, {_grid_rms(FL_OLD[1], 120):.0f} W)")
+check("⭐ a SoC reading flipping across the reserve does not swap the split: "
+      "A stays held back (0 W) and the grid stays near its target",
+      _a_jumps(FL[0], 120) == 0 and seg(FL[0], 120, 600)[0] == 0
+      and _grid_rms(FL[1], 120) < 30.0)
+check("non-vacuous: without the 1-point hysteresis the split swaps on "
+      "every flip and the grid swings",
+      _a_jumps(FL_OLD[0], 120) >= 20 and _grid_rms(FL_OLD[1], 120) > 100.0)
+REL = run(2000.0, {}, {"a": 20.0, "b": 60.0}, 300.0,
+          read=lambda u, t, lv: (20.0 if t < 100 else 21.0 if t < 200
+                                 else 22.0) if u == "a" else lv)
+check("...held back at 20 %, still at 21 %, released at 22 % (more than 1 "
+      "point above its reserve)",
+      seg(REL[0], 40, 100)[0] == 0 and seg(REL[0], 140, 200)[0] == 0
+      and seg(REL[0], 240, 300)[0] > 500)
+ID[1]._held_was = frozenset({A, B})
+check("...a battery kept held back by the hysteresis is not one that can "
+      "give: A at 20 % and B kept at 21 % hold nobody back",
+      held_back((20.0, 21.0)) == frozenset())
+
+# ============================================================================ #
+print("\n5. the rules at their boundaries")
+
+
+def stub(names, held, live=None):
+    """A Controller stand-in for `_drain_rise()`, on SIMULATED units."""
+    s = types.SimpleNamespace(
+        inverters=[types.SimpleNamespace(name=n) for n in names],
+        actuator_of=lambda src, inv=None: inv.name,
+        live_units=lambda: tuple(live or names),
+        _held_back=lambda: frozenset(held))
+    return s
+
+
+def rise(names, held, target, drains, extra=(), live=None):
+    """`_drain_rise()` then the split: (claims kinds, shares)."""
+    cl = [Claim.limit("supervised", P_SAFETY, -FULL, FULL, actuator=n)
+          for n in names]
+    cl += [Claim.set("maintenance", P_MAINTENANCE, w, DRAIN, actuator=n)
+           for n, w in drains.items()]
+    cl += list(extra)
+    res = [MaintResult(DRAIN, True, drains[n], False, []) if n in drains
+           else MaintResult(IDLE, False, None, False, []) for n in names]
+    Controller._drain_rise(stub(names, held, live), cl, res)
+    r = resolve(cl + [Claim.set("loop", 10, target)], units=tuple(names),
+                live=set(live or names), reserve=held)
+    kinds = {c.actuator: c.kind for c in cl if c.source == "maintenance"}
+    return kinds, {u: round(v) for u, v in r.shares.items()}
+
+
+_n3 = rise(("x", "y", "z"), {"z"}, 1500.0, {"x": 1000.0})
+print(f"    N=3, x draining 1000, y able, z held, 1500 W: {_n3[1]}")
+check("⭐ N=3: the draining battery keeps its drain rate as a floor (x >= "
+      "1000 W) while sharing with the able one; the held one gives nothing",
+      _n3[0] == {"x": "limit"} and _n3[1]["x"] >= 1000 and _n3[1]["z"] == 0
+      and sum(_n3[1].values()) == 1500)
+_stop = rise((A, B), {A}, 3000.0, {B: 1000.0},
+             (Claim.set("safety", P_SAFETY, 0.0, "stopped"),))
+check("⭐ a site stop decides alone: the drain stays a pin, nothing rises",
+      _stop[0] == {B: "set"} and _stop[1] == {A: 0, B: 0})
+_hd = rise((A, B), {A}, 5000.0, {A: 1000.0})
+check("...a held battery's own drain stays a pin (it is not raised for the "
+      "loop): A 1000 W, B 2500 W",
+      _hd[0] == {A: "set"} and _hd[1] == {A: 1000, B: 2500})
+_nh = rise((A, B), set(), 3000.0, {B: 1000.0})
+check("...with nothing held the drain stays a pin, as before (SAFETY-78)",
+      _nh[0] == {B: "set"} and _nh[1] == {A: 2000, B: 1000})
+_dead = rise((A, B), {A}, 3000.0, {B: 1000.0}, live=(A,))
+check("...a draining battery that is not live is not touched",
+      _dead[0] == {B: "set"})
+
+# ============================================================================ #
+print("\n6. next_quarter()")
+T0 = rig.BASE
+
+
+def proj(elapsed, covered=1.0, held=3000.0, start=T0):
+    return Projection(projected_w=2000.0, elapsed_w=1900.0, elapsed_s=elapsed,
+                      covered_frac=covered, complete=covered >= 1.0,
+                      block_start=start, held_w=held)
+
+
+_in = proj(899.0)
+_past = next_quarter(proj(900.4, covered=899.9 / 900.4), 30.0)
+check("⭐ inside its block a projection is unchanged (the same object)",
+      next_quarter(_in, 30.0) is _in)
+check("⭐ past its end with a fresh held reading: the next quarter, "
+      "projected from that reading",
+      _past.block_start == T0 + timedelta(seconds=QUARTER_S)
+      and abs(_past.elapsed_s - 0.4) < 1e-9 and _past.projected_w == 3000.0
+      and _past.covered_frac == 1.0
+      and peakguard.blindness(_past, 30.0, False) is None)
+_old = proj(960.0, covered=880.0 / 960.0)
+_edge29 = proj(901.0, covered=871.5 / 901.0)     # 29.5 s uncovered
+_edge31 = proj(901.0, covered=870.5 / 901.0)     # 30.5 s uncovered
+check("...the held reading is credited up to max_hold_s and no further "
+      "(29.5 s uncovered: rolled; 30.5 s: unchanged)",
+      next_quarter(_edge29, 30.0) is not _edge29
+      and next_quarter(_edge31, 30.0) is _edge31)
+check("...a held reading too old to be credited, no block, or an export: "
+      "unchanged, or projected at 0 W offtake",
+      next_quarter(_old, 30.0) is _old
+      and next_quarter(proj(950.0, start=None), 30.0).block_start is None
+      and next_quarter(proj(900.5, held=-800.0), 30.0).projected_w == 0.0)
+
+# ============================================================================ #
+print("\n7. N=1")
+for _name, _args in (("HOLD, late telegram at the edge",
+                      (5500.0, {A: HOLD}, {"a": 99.0}, 1000.0, 0.5)),
+                     ("drain under the reserve, house 4000",
+                      (4000.0, {A: DRAIN}, {"a": 15.0}, 600.0, 0.5))):
+    _new = run(*_args, n=1)
+    _old = without_fix(lambda: run(*_args, n=1))
+    print(f"    {_name}: A at the edge "
+          f"{[cmd(r)['a'] for r in _new[0] if 899 <= r[0] <= 901]}")
+    check(f"⭐ N=1, {_name}: every row (claims, commands, the guard) is "
+          "identical with and without the fix",
+          _new[1].maints[0].phase == _args[1][A] and len(_new[0]) > 500
+          and _new[0] == _old[0])
+_one = types.SimpleNamespace(inverters=[object()])
+_cl = [Claim.set("maintenance", P_MAINTENANCE, 1000.0, DRAIN)]
+check("⭐ at one inverter nothing is held back and no pin moves (the N=1 "
+      "identity digests in test_safety78/79/83/84/86/87 stay pinned)",
+      Controller._held_back(_one) == frozenset()
+      and Controller._drain_rise(types.SimpleNamespace(
+          inverters=[object()], _held_back=lambda: frozenset()), _cl,
+          [MaintResult(DRAIN, True, 1000.0, False, [])]) is None
+      and _cl[0].kind == "set")
+
+print()
+if fails:
+    print(f"{len(fails)} FAILED: " + ", ".join(fails))
+    sys.exit(1)
+print("all SAFETY-91 checks passed")
@@ -0,0 +1,422 @@
+"""Runnable check for SAFETY-93: the maintenance charge end hands back
+smoothly, with no grid charging at a high house. `python3 test_safety93.py`
+
+At N=2, when battery A's maintenance charge ended, its watts stayed in the
+loop's site target and landed on B: B went 0 -> -1600 W in one cycle and
+charged from the grid with the house at 6000 W (SAFETY-85 rig test, check 4).
+Now the loop starts from what B stood at plus A's new command. Drives the
+REAL Controller on a lagging battery (10 s, 2 s meter, as on the rig).
+DECISIONS/SAFETY-93-charge-end.md.
+
+1. The rig case: A charges 2000 W late in a quarter with the house at 6000 W,
+   then its charge ends (HOLD).
+2. The same at a low house.
+3. The charge ends another way: a timeout (abort) and the battery switched
+   Off.
+4. The charge ends while the guard has suspended it (A gives under the loop).
+5. N=1 is untouched; a missed poll on the end cycle; the rule at its
+   boundaries.
+
+Mutations (MUTATION.md, purged copies) are listed in the pull request.
+"""
+
+import hashlib
+import logging
+import math
+import os
+import sys
+from datetime import timedelta
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+sys.path.insert(0, os.path.join(HERE, "tools"))
+logging.disable(logging.WARNING)
+
+import opt11_identity as rig                                   # noqa: E402
+import safety79_identity as s79                                # noqa: E402
+import safety84_identity as s84                                # noqa: E402
+from app import packmode                                       # noqa: E402
+from app.main import Controller                                # noqa: E402
+from app.maintenance import (CHARGE_TIMEOUT_MIN, HOLD, IDLE,    # noqa: E402
+                             MaintResult)
+from app.store import unit_key                                 # noqa: E402
+from named_absence import first, present                       # noqa: E402
+
+fails = []
+A = "inverter-a"
+SLEW = 400.0            # the rig's slew_w
+AIM = 3500 - 50         # peak_cap_w - peak_margin_w
+OPT0 = dict(s84.OPT)
+
+
+def check(name, cond):
+    print(f"  {'ok  ' if cond else 'FAIL'} {name}")
+    if not cond:
+        fails.append(name)
+
+
+def lagging(fn, lag=10.0):
+    """plantsim's battery (800 W/s ramp, `lag` s first-order lag) at the
+    live 2 s meter tick (test_safety85.py part 7)."""
+    real_p, real_t = rig._Hass.power, rig.TICK
+
+    def power(self, u):
+        st = self.__dict__.setdefault("_plant", {})
+        a, tgt, tl = st.get(u, (0.0, 0.0, self.t))
+        for _ in range(int(round((self.t - tl) / 0.1))):
+            d = self.cmd[u] - tgt
+            tgt += math.copysign(min(abs(d), 80.0), d)
+            a += (tgt - a) * (1 - math.exp(-0.1 / lag))
+        st[u] = (a, tgt, self.t)
+        return float(round(a))
+    rig._Hass.power, rig.TICK = power, 2.0
+    try:
+        return fn()
+    finally:
+        rig._Hass.power, rig.TICK = real_p, real_t
+
+
+def run(n, house, end, *, step=None, dur=None, store=None, extra=None,
+        before=None):
+    """A charging in a cheap window from the first cycle (quarters start at
+    0, 900, 1800 s); the house is 1200 W, then `house` from `step`; A reads
+    99 % (its charge target) from `end`. Returns (rows, controller)."""
+    step = end if step is None else step
+    s84.OPT = dict(OPT0, peak_cap_w=3500)
+    feed = s84.feed(True)
+
+    def both(c, t):
+        if before is not None:
+            before(c, t)
+        feed(c, t)
+    try:
+        return lagging(lambda: s84.run(
+            n, load=lambda t: house if t >= step else 1200.0, cheap=True,
+            store=store or s79.store_charging(n),
+            soc=lambda u, t: (99.0 if t >= end else 90.0) if u == "a"
+            else 60.0, dur=dur or end + 300.0, before=both,
+            extra=dict({"maintenance_hold_min": 600}, **(extra or {}))))
+    finally:
+        s84.OPT = OPT0
+
+
+def cmd(r):
+    return dict(r[2])
+
+
+def moves(rows, u, lo, hi):
+    """The largest change in battery `u`'s command between cycles in
+    (lo, hi]."""
+    return max(abs(cmd(b)[u] - cmd(a)[u]) for a, b in zip(rows, rows[1:])
+               if lo < b[0] <= hi)
+
+
+def charging_hi(rows, lo, hi, house_at):
+    """Cycles in [lo, hi] where a battery charges while the house is above
+    the peak aim."""
+    return sum(1 for r in rows if lo <= r[0] <= hi and house_at(r[0]) > AIM
+               and min(cmd(r).values()) < 0.0)
+
+
+# None on a tree without the fix (f3e409c), where this file runs red.
+no_fix = getattr(Controller, "_reseed_charge_end", None)
+
+
+def without(fn):
+    """Run `fn` with the SAFETY-93 reseed taken out."""
+    if no_fix is None:
+        return fn()
+    Controller._reseed_charge_end = lambda self, ended: None
+    try:
+        return fn()
+    finally:
+        Controller._reseed_charge_end = no_fix
+
+
+def phase_at(rows, t):
+    return first((r[-1][3][0] for r in rows if r[0] == t), f"row {t}")
+
+
+def at(rows, t, u):
+    """Battery `u`'s command at `t` s."""
+    r = first((r for r in rows if r[0] == t), f"row {t}")
+    return dict(r[2])[u] if present(r) else r
+
+
+# ============================================================================ #
+print("1. the rig case: A charges 2000 W late in a quarter, house 6000 W")
+# House 1200 W until 1760 s, then 6000 W; the quarter (900-1800 s) has room,
+# so the charge stays at 2000 W. A is full at 1780 s. Graded to 1798 s: the
+# guard grades a new quarter from 1800 s.
+R1 = run(2, 6000.0, 1780.0, step=1760.0)
+R1_old = without(lambda: run(2, 6000.0, 1780.0, step=1760.0))
+
+
+def hi1(t):
+    return 6000.0 if t >= 1760.0 else 1200.0
+
+
+for name, (rows, _c) in (("now", R1), ("without the fix", R1_old)):
+    print(f"    {name}: " + ", ".join(
+        f"{r[0]:.0f}s A {cmd(r)['a']:.0f} B {cmd(r)['b']:.0f}"
+        for r in rows if 1776 <= r[0] <= 1786))
+_r, _ = R1
+check("the case is the rig's: A charges 2000 W with the house at 6000 W the "
+      "cycle before its charge ends, then holds",
+      at(_r, 1778.0, "a") == -2000.0
+      and phase_at(_r, 1778.0) == "charge" and phase_at(_r, 1780.0) == HOLD)
+check("⭐ no battery charges from the grid after the charge ends (house above "
+      "the aim)", charging_hi(_r, 1780, 1798, hi1) == 0)
+check("⭐ B moves at most one slew step a cycle across the charge end, and A "
+      "after its HOLD pin", moves(_r, "b", 1776, 1798) <= SLEW
+      and moves(_r, "a", 1780, 1798) <= SLEW)
+check("...and B gives toward the house at once (+400 W at the end cycle)",
+      at(_r, 1780.0, "b") == SLEW)
+check("non-vacuous: without the fix B jumps 0 -> -1600 W and charges from "
+      "the grid for 4 cycles", moves(R1_old[0], "b", 1776, 1798) >= 1600
+      and charging_hi(R1_old[0], 1780, 1798, hi1) >= 4)
+
+# ============================================================================ #
+print("\n2. the same at a low house")
+R2 = run(2, 1200.0, 1300.0)
+R2_old = without(lambda: run(2, 1200.0, 1300.0))
+print(f"    B's largest move: {moves(R2[0], 'b', 1296, 1600):.0f} W, without "
+      f"the fix {moves(R2_old[0], 'b', 1296, 1600):.0f} W; B's least "
+      f"command after the end "
+      f"{min(cmd(r)['b'] for r in R2[0] if r[0] >= 1300):.0f}"
+      f" W, without {min(cmd(r)['b'] for r in R2_old[0] if r[0] >= 1300):.0f}"
+      " W")
+check("⭐ house 1200 W: B moves at most one slew step a cycle and never "
+      "charges from the grid after A's charge ends",
+      moves(R2[0], "b", 1296, 1600) <= SLEW
+      and min(cmd(r)["b"] for r in R2[0] if r[0] >= 1300) >= 0.0)
+check("non-vacuous: without the fix B jumps to -1600 W (2800 W from the grid)",
+      min(cmd(r)["b"] for r in R2_old[0] if r[0] >= 1300) <= -1600.0)
+
+# ============================================================================ #
+print("\n3. the charge ends another way")
+
+
+def timed_out(end):
+    """A store whose charge passes CHARGE_TIMEOUT_MIN at `end` s."""
+    s = s79.store_charging(2)
+    s.data[unit_key(A, "phase_started")] = (
+        rig.BASE + timedelta(seconds=end - CHARGE_TIMEOUT_MIN * 60 - 1)
+    ).isoformat()
+    return s
+
+
+def b_done():
+    """A charging; B finished its monthly cycle, so it starts none here."""
+    s = s79.store_charging(2)
+    s.data[unit_key("inverter-b", "last_completed")] = rig.BASE.isoformat()
+    return s
+
+
+def switch_off(at):
+    """Battery A switched Off at `at` s (OPT-11 modes on)."""
+    def before(c, t):
+        if t >= at:
+            c.store.data[unit_key(A, packmode.USE_KEY)] = False
+    return before
+
+
+ENDS = {
+    "timeout": lambda: run(2, 6000.0, 9999.0, step=1760.0, dur=2080.0,
+                           store=timed_out(1780.0)),
+    "Off": lambda: run(2, 6000.0, 9999.0, step=1760.0, dur=2080.0,
+                       store=b_done(), before=switch_off(1780.0),
+                       extra={"battery_modes_enabled": True}),
+}
+for k, fn in ENDS.items():
+    rows, c = fn()
+    old = without(fn)[0]
+    print(f"    {k}: A {[cmd(r)['a'] for r in rows if 1776 <= r[0] <= 1784]}"
+          f" B {[cmd(r)['b'] for r in rows if 1776 <= r[0] <= 1784]}; "
+          f"without the fix B "
+          f"{[cmd(r)['b'] for r in old if 1776 <= r[0] <= 1784]}")
+    check(f"{k}: the charge ends at 1780 s",
+          phase_at(rows, 1778.0) == "charge"
+          and phase_at(rows, 1780.0) == IDLE)
+    check(f"⭐ {k}: no battery charges from the grid after it, and B moves at "
+          f"most one slew step a cycle",
+          charging_hi(rows, 1780, 1798, hi1) == 0
+          and moves(rows, "b", 1776, 1798) <= SLEW)
+    check(f"non-vacuous ({k}): without the fix B jumps to -1600 W, from "
+          f"the grid", at(old, 1780.0, "b") == -1600.0
+          and charging_hi(old, 1780, 1798, hi1) >= 1)
+
+# ============================================================================ #
+print("\n4. the charge ends while the guard has suspended it")
+# House 6000 W from 1500 s: the guard suspends the shaping, the loop has both
+# batteries give. A is full at 1530 s; its HOLD pin takes it to 0 W.
+R4 = run(2, 6000.0, 1530.0, step=1500.0)
+R4_old = without(lambda: run(2, 6000.0, 1530.0, step=1500.0))
+_a4 = at(R4[0], 1528.0, "a")
+print(f"    A gave {_a4:.0f} W before its HOLD; B's largest move "
+      f"{moves(R4[0], 'b', 1526, 1798):.0f} W, without the fix "
+      f"{moves(R4_old[0], 'b', 1526, 1798):.0f} W")
+check("A gives under the loop before its charge ends",
+      present(_a4) and _a4 > SLEW and R4[1].maints[0].phase == HOLD)
+check("⭐ B takes A's share at one slew step a cycle (A's own give stops "
+      "with its HOLD pin, as before)", moves(R4[0], "b", 1526, 1798) <= SLEW
+      and charging_hi(R4[0], 1530, 1798, lambda t: 6000.0) == 0)
+check("non-vacuous: without the fix B jumps more than a slew step",
+      moves(R4_old[0], "b", 1526, 1798) > SLEW)
+
+# ============================================================================ #
+print("\n5. N=1 is untouched; a missed poll; the rule at its boundaries")
+
+
+def digest(rows):
+    return hashlib.sha256(repr(rows).encode()).hexdigest()
+
+
+_n1 = [digest(run(1, h, e, step=s)[0]) for h, e, s in
+       ((6000.0, 1780.0, 1760.0), (1200.0, 1300.0, None))]
+_n1_old = [digest(without(lambda: run(1, h, e, step=s))[0]) for h, e, s in
+           ((6000.0, 1780.0, 1760.0), (1200.0, 1300.0, None))]
+check("⭐ N=1, the charge ending at a high and a low house: every row "
+      "byte-identical with and without the reseed", _n1 == _n1_old)
+
+if no_fix is None:
+    print(f"\n{len(fails)} FAILED (no _reseed_charge_end): " + ", ".join(fails))
+    sys.exit(1)
+
+
+def missed_poll(at_t):
+    """Battery B's power reading is missing on the cycle at `at_t` s."""
+    def before(c, t):
+        if not getattr(c.hass, "_s93", False):
+            read = c.hass.number
+
+            async def number(e, invert=False):
+                if e == "sensor.batt_b" and c.hass.t == at_t:
+                    return None
+                return await read(e, invert)
+            c.hass.number, c.hass._s93 = number, True
+    return before
+
+
+R6 = run(2, 6000.0, 1780.0, step=1760.0, before=missed_poll(1780.0))
+R6_old = without(lambda: run(2, 6000.0, 1780.0, step=1760.0,
+                             before=missed_poll(1780.0)))
+print(f"    a missed poll on the end cycle: B "
+      f"{[cmd(r)['b'] for r in R6[0] if 1778 <= r[0] <= 1786]}, without "
+      f"the fix {[cmd(r)['b'] for r in R6_old[0] if 1778 <= r[0] <= 1786]}")
+check("a missed poll on the cycle the charge ends: the loop holds that cycle",
+      phase_at(R6[0], 1780.0) == HOLD
+      and "inputs missing" in str(first(r[6] for r in R6[0] if r[0] == 1780.0)))
+check("⭐ ...and the end still reaches the loop on the next cycle: no grid "
+      "charge (A's charge stands through the held cycle), one slew step a "
+      "cycle", charging_hi(R6[0], 1782, 1798, hi1) == 0
+      and moves(R6[0], "b", 1776, 1798) <= SLEW)
+check("non-vacuous: without the fix B charges from the grid",
+      charging_hi(R6_old[0], 1782, 1798, hi1) >= 1)
+_c = R1[1]
+
+
+def reseeded(target, shares, res, ended=frozenset({A})):
+    """`_reseed_charge_end` on the rig's controller, A's charge ended and
+    its result `res`: (target, i_w)."""
+    _c.target, _c.i_w, _c._charge_ended = target, 123.0, ended
+    for inv in _c.inverters:
+        inv.target = shares[inv.name[-1]]
+    _c._reseed_charge_end([res, _free])
+    return _c.target, _c.i_w
+
+
+_pin = MaintResult(HOLD, True, 0.0, False, [])
+_free = MaintResult(IDLE, False, None, False, [])
+check("a HOLD pin: the start is B's command plus the pin, integrator with it",
+      reseeded(-2000.0, {"a": -2000.0, "b": 0.0}, _pin) == (0.0, 0.0)
+      and reseeded(2770.0, {"a": 1385.0, "b": 1385.0}, _pin)
+      == (1385.0, 1385.0) and _c._charge_ended == frozenset())
+check("a free battery: its charge leaves the start, its discharge stays",
+      reseeded(-2000.0, {"a": -2000.0, "b": 0.0}, _free) == (0.0, 0.0)
+      and reseeded(2770.0, {"a": 1385.0, "b": 1385.0}, _free)
+      == (2770.0, 2770.0))
+check("no charge ended: nothing moves (the integrator either)",
+      reseeded(-2000.0, {"a": -2000.0, "b": 0.0}, _pin, frozenset())
+      == (-2000.0, 123.0))
+_n1c = run(1, 6000.0, 1780.0, step=1760.0)[1]
+_n1c.target, _n1c.i_w = -2000.0, 5.0
+_n1c.inverters[0].target, _n1c._charge_ended = -2000.0, frozenset({A})
+_n1c._reseed_charge_end([_pin])
+check("N=1: nothing moves", (_n1c.target, _n1c.i_w) == (-2000.0, 5.0))
+_seen = []
+
+
+def _spy(self, maint_results):
+    _seen.append(sorted(self._charge_ended))
+    return no_fix(self, maint_results)
+
+
+Controller._reseed_charge_end = _spy
+try:
+    run(2, 6000.0, 1780.0, step=1760.0, dur=2400.0,
+        extra={"maintenance_hold_min": 5})
+finally:
+    Controller._reseed_charge_end = no_fix
+check("it fires once, at the charge end: not at the HOLD end or on any "
+      "other cycle", [x for x in _seen if x] == [[A]]
+      and len(_seen) > 300)
+
+# ============================================================================ #
+print("\n6. A still in CHARGE but no longer placed: stale link, refusal")
+
+
+def link_drop(at):
+    """A's writes rejected from `at` s, so it is dropped as a stale link."""
+    def before(c, t):
+        a = c.inverters[0]
+        if t >= at and a.rejected_since is None:
+            a.rejected_since = rig.BASE + timedelta(seconds=at)
+    return before
+
+
+def refuses(at):
+    """A stops charging from `at` s (reads 0 W); SAFETY-73 drops it."""
+    def before(c, t):
+        if not getattr(c.hass, "_s93r", False):
+            real = c.hass.power
+
+            def power(u):
+                p = real(u)
+                return 0.0 if u == "a" and c.hass.t >= at and p < 0 else p
+            c.hass.power, c.hass._s93r = power, True
+    return before
+
+
+for k, hook in (("stale link", link_drop), ("refusal", refuses)):
+    def fn(hook=hook):
+        return run(2, 1200.0, 9999.0, dur=1500.0, before=hook(1300.0))
+    rows, _c6 = fn()
+    old = without(fn)[0]
+    drop = first((r[0] for r in rows if r[0] >= 1300
+                  and "dropped inverter-a" in str(r[7])), "A dropped")
+    print(f"    {k}: A dropped at {drop:.0f} s; B "
+          f"{[cmd(r)['b'] for r in rows if drop - 2 <= r[0] <= drop + 4]}, "
+          f"without the fix {[cmd(r)['b'] for r in old if drop - 2 <= r[0] <= drop + 4]}")
+    check(f"⭐ {k}: A is dropped while still in CHARGE, and B never charges "
+          f"from the grid and moves at most one slew step a cycle",
+          phase_at(rows, drop) == "charge"
+          and min(cmd(r)["b"] for r in rows if r[0] >= 1300) >= 0.0
+          and moves(rows, "b", 1296, 1500) <= SLEW)
+    check(f"non-vacuous ({k}): without the fix B jumps to -1600 W",
+          min(cmd(r)["b"] for r in old if r[0] >= 1300) <= -1600.0)
+
+_seen.clear()
+Controller._reseed_charge_end = _spy
+try:
+    run(2, 6000.0, 1530.0, step=1500.0)
+finally:
+    Controller._reseed_charge_end = no_fix
+check("the guard suspending the charge is no end: it fires once, at the HOLD",
+      [x for x in _seen if x] == [[A]])
+
+print()
+if fails:
+    print(f"{len(fails)} FAILED: " + ", ".join(fails))
+    sys.exit(1)
+print("all SAFETY-93 checks passed")
@@ -0,0 +1,361 @@
+"""Runnable check for SAFETY-94: a healthy battery that lags or reverses is
+not flagged as frozen or refusing. `python3 test_safety94.py`
+
+Two false alarms, both pre-existing:
+- The stale-reading gate (SAFETY-37) counted its 35 s from the register's last
+  change. After a rest that clock was already past 35 s, so the first read
+  after a new command tripped it, before the register could answer (SAFETY-58;
+  live 2026-10-03, four trips, each 1 s after a command).
+- At N=1 the refusal (SAFETY-52) engaged after 12 frozen cycles if the reading
+  was under 100 W at that moment. At a 1 s meter, a battery reversing out of a
+  charge through its lag is passing 0 W just then (SAFETY-85 rig, O1). It was
+  held at 0 W until the next probe, up to 15 min.
+
+Now the gate counts only the time the command asked the register to move, and
+a refusal needs the reading to have stayed under 100 W, not moving towards the
+ask, for 12 cycles spanning 22 s, at every roster size.
+DECISIONS/SAFETY-94-lagging-battery.md.
+
+1. The four live trips, replayed through the gate.
+2. The REAL Controller on a lagging battery (tools/safety94_rig.py), N=1 and
+   N=2: rest then a step, maintenance drain start, drain -> charge, a charge
+   reversing into a discharge. No stale trip and no refusal.
+3. A frozen register and a refusing battery are still caught, and how fast.
+4. The rules at their edges.
+
+Mutations (MUTATION.md, purged copies) are listed in the pull request.
+"""
+
+import logging
+import os
+import sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+sys.path.insert(0, os.path.join(HERE, "tools"))
+logging.disable(logging.CRITICAL)
+
+import safety94_rig as rig                                    # noqa: E402
+import app.inverter as app_inverter                            # noqa: E402
+import app.main as app_main                                    # noqa: E402
+from app import control                                        # noqa: E402
+from app.freshness import BOUNDS, Freshness                    # noqa: E402
+
+fails = []
+
+
+def check(name, cond):
+    print(f"  {'ok  ' if cond else 'FAIL'} {name}")
+    if not cond:
+        fails.append(name)
+
+
+class Before94(Freshness):
+    """The gate before SAFETY-94: the clock ran from the last change."""
+
+    def obliged_s(self):
+        return self.graded_s(self.last_read)
+
+
+def without_fix(fn):
+    """Run `fn` with the gate's old clock and the old refusal evidence."""
+    real_f, real_c = app_inverter.Freshness, app_main.compute
+    real_p = app_main.REFUSED_PROGRESS_W
+    app_inverter.Freshness = Before94
+    app_main.compute = lambda *a, **k: real_c(*a, **dict(k, gave_nothing=None))
+    app_main.REFUSED_PROGRESS_W = float("inf")
+    try:
+        return fn()
+    finally:
+        app_inverter.Freshness, app_main.compute = real_f, real_c
+        app_main.REFUSED_PROGRESS_W = real_p
+
+
+# ============================================================================ #
+print("1. the four live trips of 2026-10-03, replayed")
+# HA history (only changes are recorded), local time: the unit's setpoint
+# (what stands on its wire) and its battery power register (0x0518).
+LIVE = {
+    "17:39:16 inverter-b": (
+        [("17:38:00", -24), ("17:38:14.7", 0), ("17:38:25.4", 5),
+         ("17:38:40.5", 16), ("17:38:44.7", 26), ("17:38:55.7", 37),
+         ("17:39:05.1", 42), ("17:39:09.8", 58), ("17:39:15.6", 268),
+         ("17:39:25.0", 479), ("17:39:30.7", 689), ("17:39:34.8", 900)],
+        [("17:38:00", -118), ("17:38:21.6", -99), ("17:39:21.6", 179),
+         ("17:39:31.6", 399)]),
+    "17:39:25 inverter-a": (
+        [("17:38:00", -16), ("17:38:14.9", 0), ("17:38:25.0", 5),
+         ("17:38:40.0", 14), ("17:38:44.7", 24), ("17:38:55.2", 33),
+         ("17:39:04.7", 38), ("17:39:09.3", 52), ("17:39:15.0", 242),
+         ("17:39:24.6", 431), ("17:39:30.3", 621), ("17:39:34.8", 810)],
+        [("17:38:00", -3), ("17:38:25.9", 0), ("17:39:25.9", 318),
+         ("17:39:36.0", 654)]),
+    "19:00:04 inverter-a": (
+        [("18:58:30.0", 290), ("18:58:43.3", 305), ("18:58:48.0", 314),
+         ("18:58:52.5", 300), ("19:00:03.1", 2500)],
+        [("18:58:30.0", 292), ("19:00:06.0", 951), ("19:00:16.0", 2360),
+         ("19:00:26.0", 2376)]),
+    "21:21:22 inverter-b": (
+        [("21:19:30.0", 0), ("21:21:21.9", 2100), ("21:21:26.6", 1700),
+         ("21:21:31.1", 1300), ("21:21:36.9", 900), ("21:21:41.0", 500),
+         ("21:21:47.3", 200)],
+        [("21:19:30.0", -98), ("21:21:22.8", -97), ("21:21:32.8", 1411),
+         ("21:21:42.8", 798)]),
+}
+
+
+def _sec(hms):
+    h, m, s = hms.split(":")
+    return int(h) * 3600 + int(m) * 60 + float(s)
+
+
+def replay(cls, setp, reg):
+    """1 Hz reads, as `run_control()` does. Returns the trip times."""
+    f, trips = cls(BOUNDS["batt"]), []
+    t, end = _sec(setp[0][0]), _sec(reg[-1][0])
+
+    def at(series, t):
+        return [float(v) for ts, v in series if _sec(ts) <= t][-1]
+    while t <= end:
+        was = f.stale
+        f.submit(at(reg, t), at(setp, t), t)
+        if f.stale and not was:
+            trips.append(t)
+        t += 1.0
+    return trips
+
+
+for name, (setp, reg) in LIVE.items():
+    old, new = replay(Before94, setp, reg), replay(Freshness, setp, reg)
+    print(f"    {name}: before {[f'{int(t // 3600):02d}:{int(t % 3600 // 60):02d}:{t % 60:04.1f}' for t in old]}"
+          f", now {len(new)} trips")
+    check(f"{name}: the shipped trip reproduces 1-2 s after the command, and "
+          f"now there is none (the register answered within 11 s)",
+          len(old) == 1 and abs(old[0] - _sec(name.split()[0])) < 1.0
+          and new == [])
+
+# ============================================================================ #
+print("\n2. the REAL Controller on a lagging battery (10 s lag)")
+# Two register shapes: published every 10 s and repeating its value (the
+# boards, live), and every 1 s with +-1 W of dither (the SAFETY-85 rig).
+SHAPES = ((10.0, False), (1.0, True))
+NAMES = ("rest_step", "drain_start", "drain_charge", "reversal")
+
+
+def sweep(fn=lambda f: f()):
+    out = {}
+    for n in (1, 2):
+        for name in NAMES:
+            for tick in (1.0, 2.0, 5.0):
+                for pub, dith in SHAPES:
+                    s, r, _ = fn(lambda: rig.counts(n, name, tick=tick,
+                                                    publish_s=pub,
+                                                    dither=dith))
+                    out[(n, name, tick, pub)] = (s, r)
+    return out
+
+
+NOW = sweep()
+OLD = sweep(without_fix)
+for n in (1, 2):
+    for name in NAMES:
+        now = [NOW[k] for k in NOW if k[:2] == (n, name)]
+        old = [OLD[k] for k in OLD if k[:2] == (n, name)]
+        print(f"    N={n} {name:12s} stale/refused now "
+              f"{sum(a for a, _ in now)}/{sum(b for _, b in now)}, before "
+              f"{sum(a for a, _ in old)}/{sum(b for _, b in old)}")
+check("⭐ no stale trip and no refusal, at N=1 and N=2, at 1, 2 and 5 s meters, "
+      "on both register shapes: a step after a rest, a drain start, drain -> "
+      "charge and a charge reversing into a discharge",
+      all(v == (0, 0) for v in NOW.values()) and len(NOW) == 48)
+check("non-vacuous: before, the same runs trip the gate (drain start and "
+      "drain -> charge at both N, as live) and refuse at N=1 on a 1 s meter",
+      sum(OLD[(n, nm, t, 10.0)][0] for n in (1, 2)
+          for nm in ("drain_start", "drain_charge") for t in (1.0, 2.0, 5.0))
+      >= 12 and OLD[(1, "drain_charge", 1.0, 1.0)][1] >= 1)
+
+
+def reversals(n, tick, taus=(10.0, 20.0)):
+    """A charge reversing into a discharge: (stale trips, refusals) summed."""
+    s = r = 0
+    for tau in taus:
+        for charge in (-1500.0, -2500.0):
+            for house in (300.0, 800.0, 2000.0):
+                for pub, dith in SHAPES:
+                    x = rig.run(n, rig.reversal(300.0, charge, house), 600.0,
+                                tau=tau, tick=tick, publish_s=pub,
+                                dither=dith)
+                    s, r = s + len(x["stale"]), r + len(x["refused"])
+    return s, r
+
+
+REV = {(n, t): reversals(n, t) for n in (1, 2) for t in (1.0, 2.0)}
+REV_OLD = {(n, 1.0): without_fix(lambda n=n: reversals(n, 1.0)) for n in (1, 2)}
+print(f"    reversals (lag 10 and 20 s): now {REV}, before {REV_OLD}")
+check("⭐ SAFETY-94's case: a battery reversing out of a charge (1500 or 2500 "
+      "W) into a 300-2000 W house, lag 10 or 20 s, 1 or 2 s meter, is never "
+      "refused or flagged, at N=1 or N=2",
+      all(v == (0, 0) for v in REV.values()))
+check("non-vacuous: before, the 1 s meter refuses at N=1 (lag 20 s) and at "
+      "N=2 (B, lag 20 s, its reading 100 W below its power)",
+      REV_OLD[(1, 1.0)][1] >= 1 and REV_OLD[(2, 1.0)][1] >= 1)
+
+# ============================================================================ #
+print("\n3. a frozen register and a refusing battery are still caught")
+
+
+def obliged_at(rows, t_f):
+    """First cycle from `t_f` where A's command is 250 W or more and has moved
+    250 W from where it stood at `t_f`."""
+    c0 = None
+    for row in rows:
+        if row[0] >= t_f and c0 is None:
+            c0 = row[2]["a"]
+        if c0 is not None and abs(row[2]["a"]) >= 250 \
+                and abs(row[2]["a"] - c0) >= 250:
+            return row[0]
+    return None
+
+
+CATCH = {}
+for n in (1, 2):
+    for tick in (1.0, 5.0):
+        # frozen while giving 1000 W, then the house steps
+        r1 = rig.run(n, lambda t: 3000.0 if t >= 400 else 1000.0, 520.0,
+                     tick=tick, publish_s=1.0, dither=True,
+                     freeze_at=lambda u: 300.0 if u == "a" else None)
+        ob = obliged_at(r1["rows"], 300.0)
+        st = [t for t, u in r1["stale"] if u == "inverter-a"]
+        # frozen at rest (HW-01's shape), the house steps 500 s later
+        r2 = rig.run(n, lambda t: 2500.0 if t >= 600 else 0.0, 700.0,
+                     tick=tick, publish_s=1.0, dither=True,
+                     freeze_at=lambda u: 100.0 if u == "a" else None)
+        ob2 = obliged_at(r2["rows"], 100.0)
+        park = min([t for t, u in r2["stale"] if u == "inverter-a"]
+                   + [t for t, _u in r2["refused"]] or [None])
+        # a refusing battery from 300 s
+        r3 = rig.run(n, lambda t: 3000.0, 420.0, tick=tick, publish_s=10.0,
+                     cut=lambda u, t: u == "a" and t >= 300.0)
+        ref = [t for t, _u in r3["refused"]]
+        CATCH[(n, tick)] = (st[0] - ob if st and ob is not None else None,
+                            park - ob2 if park is not None and ob2 is not None
+                            else None, ref[0] - 300.0 if ref else None)
+print("    (N, meter): (frozen giving: trip after the command moved, frozen "
+      "at rest: 0 W after, refusing: refused after the cut), in s")
+print(f"    {CATCH}")
+check("⭐ a register frozen while giving is caught 35 s after the command asks "
+      "it to move (the SAFETY-37 bound, now counted from the ask)",
+      all(v[0] == BOUNDS["batt"].unchanged_s for v in CATCH.values()))
+check("⭐ a register frozen at rest reads like a refusing battery: the "
+      "battery is at 0 W, refused or stale, within 36 s of the ask",
+      all(v[1] is not None and v[1] <= 36.0 for v in CATCH.values()))
+check("⭐ a refusing battery is still refused: within 22 s plus one 10 s "
+      "publish at a 1 s meter, and within 12 cycles plus a publish at 5 s",
+      all(CATCH[(n, 1.0)][2] is not None and CATCH[(n, 1.0)][2] <= 32.0
+          for n in (1, 2))
+      and all(CATCH[(n, 5.0)][2] is not None
+              and CATCH[(n, 5.0)][2] <= 12 * 5.0 + 10.0 for n in (1, 2)))
+
+# ============================================================================ #
+print("\n4. the rules at their edges")
+# The gate counts time the register was asked to move, across a flapping
+# command too.
+f = Freshness(BOUNDS["batt"])
+trip = None
+for t in range(0, 200):
+    f.submit(-3.0, 1500.0 if (t // 5) % 2 else 0.0, float(t))
+    if f.stale and trip is None:
+        trip = t
+print(f"    command flapping 0 / 1500 W every 5 s, register frozen: trip at "
+      f"{trip} s")
+check("a frozen register under a command that flaps in and out of the ask is "
+      "still caught (after 35 s of asking, about 70 s here)",
+      trip is not None and 65 <= trip <= 75)
+f = Freshness(BOUNDS["batt"])
+for t in range(0, 30):
+    f.submit(-3.0, 1500.0, float(t))
+f.submit(400.0, 1500.0, 30.0)                 # it answers
+for t in range(31, 60):
+    f.submit(400.0, 1500.0, float(t))
+check("a register that answers starts a fresh count: 30 s asked, then it "
+      "moves, then 29 s more is not stale",
+      not f.stale and f.obliged_s() < 35.0)
+f = Freshness(BOUNDS["batt"])
+for t in range(0, 600):
+    f.submit(-3.0, 200.0 if t % 60 < 3 else 0.0, float(t))
+check("a command that never asks 250 W is never an ask (SAFETY-52's 200 W "
+      "probe cannot arm the gate)",
+      not f.stale and f.obliged_s() == 0.0)
+# Review: time under 250 W is not counted, even after the command travelled.
+f = Freshness(BOUNDS["batt"])
+for t in range(0, 61):
+    f.submit(-300.0, -300.0 if t == 0 else 200.0, float(t))
+for t in range(61, 131):
+    f.submit(-300.0, 260.0, float(t))
+    if t == 90:
+        early = f.stale
+check("a command that has travelled 500 W but stands at 200 W for a minute "
+      "adds nothing: 30 s after it reaches 260 W the register is not stale, "
+      "and by 70 s it is",
+      not early and f.stale)
+
+# compute(): `gave_nothing` gates the N=1 engage; None keeps the old law.
+T = control.Tuning(max_w=4000.0, slew_w=400.0)
+args = dict(prev_w=1200.0, grid_w=1200.0, actual_w=-20.0, tuning=T,
+            sat_count=control.SETTLE_CYCLES, i_w=1200.0, refused=0)
+check("compute(): a frozen loop at SETTLE_CYCLES reading -20 W engages with "
+      "gave_nothing None (compute alone, as before) or True, and not with "
+      "False",
+      control.compute(**args).refused == 1
+      and control.compute(**args, gave_nothing=True).refused == 1
+      and control.compute(**args, gave_nothing=False).refused == 0)
+
+# The evidence restarts on progress towards the ask, not on jitter.
+print(f"    REFUSED_PROGRESS_W {app_main.REFUSED_PROGRESS_W:.0f} W, span "
+      f"{app_main.REFUSED_SPAN_S:.0f} s")
+
+
+class _Inv:
+    def __init__(self):
+        self.batt, self.ref_count, self.ref_since, self.ref_sign = 0.0, 0, None, 0
+        self.ref_from = None
+        self.idle_w = 0.0                     # SAFETY-97: A, ~0 W at idle
+        self.ask = 800.0
+
+    def standing_w(self):
+        return self.ask
+
+
+class _C:
+    _now_mono = 0.0
+
+
+def evidence(readings, tick=1.0, ask=lambda i: 800.0):
+    c, inv = _C(), _Inv()
+    got = []
+    for i, b in enumerate(readings):
+        c._now_mono, inv.batt, inv.ask = i * tick, b, ask(i)
+        got.append(app_main.Controller._gave_nothing(c, inv))
+    return got
+
+
+flat = evidence([-4.0 + (i % 3) for i in range(30)])
+climb = evidence([-95.0 + 4.0 * i for i in range(48)])
+check("a flat reading (+-1 W) under an 800 W ask is evidence after 22 s; one "
+      "climbing 4 W/s through the band is never",
+      1 in flat and flat.index(1) == 22 and not any(climb))
+flap = evidence([-4.0] * 60, ask=lambda i: 800.0 if i % 2 else -800.0)
+away = evidence([40.0] * 5 + [-40.0] * 25)
+check("a command that swaps direction every cycle is never evidence, and a "
+      "reading moving 80 W away from the ask does not restart it (latched at "
+      "22 s, counted from the first reading)",
+      not any(flap) and 1 in away and away.index(1) == 22)
+check("REFUSED_PROGRESS_W is under the band's width and over the live "
+      "readings' rest wander (25 W)",
+      25.0 < app_main.REFUSED_PROGRESS_W < 2 * control.REFUSED_BELOW_W)
+
+print()
+if fails:
+    print(f"{len(fails)} FAILED: " + ", ".join(fails))
+    sys.exit(1)
+print("all checks passed")
@@ -0,0 +1,441 @@
+"""Runnable check for SAFETY-97: "the battery gives nothing" is graded against
+each battery's own idle reading. `python3 test_safety97.py`
+
+B's power reading shows -95 to -118 W at idle (standby draw; live
+2026-10-03). The refusal evidence (SAFETY-52/73, shared since SAFETY-94)
+needed the reading under 100 W in magnitude, so a refusing B never latched,
+at N=2 ever, and at N=1 since SAFETY-94 (review F1).
+
+Now each unit learns its idle reading (app/idle.py) and the band, the
+refusal's end and the stale-path refusal are centred on it.
+DECISIONS/SAFETY-97-idle-offset.md.
+
+1. A refusing B is caught at N=1 and N=2, 1/2/5 s meters; A unchanged.
+2. A healthy B with its offset is never refused or flagged (SAFETY-94's
+   scenarios), learned or restored.
+3. Learning: not while refusing or asked, bounded, restored, follows drift.
+4. The rules at their edges.
+
+Mutations (MUTATION.md, purged copies) are listed in the pull request.
+"""
+
+import logging
+import os
+import sys
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+sys.path.insert(0, HERE)
+sys.path.insert(0, os.path.join(HERE, "tools"))
+logging.disable(logging.CRITICAL)
+
+import safety94_rig as rig                                    # noqa: E402
+import app.idle as idle                                        # noqa: E402
+import app.main as app_main                                    # noqa: E402
+from app import control                                        # noqa: E402
+from app.store import unit_key                                 # noqa: E402
+
+fails = []
+
+
+def check(name, cond):
+    print(f"  {'ok  ' if cond else 'FAIL'} {name}")
+    if not cond:
+        fails.append(name)
+
+
+def without_fix(fn):
+    """Run `fn` with every idle reading at 0 W (the rule before SAFETY-97)."""
+    real = idle.IdleReading.w
+    idle.IdleReading.w = property(lambda self: 0.0)
+    try:
+        return fn()
+    finally:
+        idle.IdleReading.w = real
+
+
+def with_offset(n, fn):
+    """At N=1 the rig's only unit is "a": give it B's offset."""
+    saved = dict(rig.OFFSET)
+    if n == 1:
+        rig.OFFSET["a"] = rig.OFFSET["b"]
+    try:
+        return fn()
+    finally:
+        rig.OFFSET.clear()
+        rig.OFFSET.update(saved)
+
+
+REST, CUT = 400.0, 600.0           # rest (it learns), then ask, then cut
+REST_LOAD = (lambda t: 0.0 if t < REST else 3000.0)
+
+
+def caught(n, unit, tick, *, offset=True, dur=None, store=None, load=None,
+           cut_at=CUT, **kw):
+    """Seconds from the cut to the refusal, or None, and the run."""
+    cu = "a" if n == 1 else unit
+
+    def go():
+        return rig.run(n, load or REST_LOAD, dur or cut_at + 300.0,
+                       tick=tick, noise=4.0, store=store,
+                       cut=lambda u, t: u == cu and t >= cut_at, **kw)
+    r = with_offset(n, go) if offset and unit == "b" else go()
+    ref = [t - cut_at for t, _u in r["refused"]]
+    return (ref[0] if ref else None), r
+
+
+# ============================================================================ #
+print("1. a refusing battery, B with its -100 W idle reading (+-4 W noise)")
+TIMES, OLD = {}, {}
+for unit in ("a", "b"):
+    for n in (1, 2):
+        for tick in (1.0, 2.0, 5.0):
+            TIMES[(unit, n, tick)] = caught(n, unit, tick)[0]
+            OLD[(unit, n, tick)] = without_fix(
+                lambda: caught(n, unit, tick)[0])
+for k in TIMES:
+    print(f"    refusing {k[0].upper()} N={k[1]} meter {k[2]:.0f} s: refused "
+          f"{TIMES[k]} s after the cut (before {OLD[k]})")
+check("⭐ a refusing B is caught at N=1 and N=2: within 22 s plus one 10 s "
+      "publish at 1 and 2 s meters, 12 cycles plus a publish at 5 s",
+      all(TIMES[("b", n, t)] is not None
+          and TIMES[("b", n, t)] <= (32.0 if t < 5 else 12 * 5.0 + 10.0)
+          for n in (1, 2) for t in (1.0, 2.0, 5.0)))
+check("non-vacuous: before, a refusing B is never caught (300 s), at N=1 "
+      "or N=2",
+      all(OLD[("b", n, t)] is None for n in (1, 2) for t in (1.0, 2.0, 5.0)))
+check("⭐ a refusing A is caught exactly as before",
+      all(TIMES[("a", n, t)] == OLD[("a", n, t)] is not None
+          for n in (1, 2) for t in (1.0, 2.0, 5.0)))
+
+# B refusing for 800 s: one refusal, held, not ended by its own idle reading.
+_t, r = caught(2, "b", 1.0, dur=CUT + 800.0)
+starts = [x for x in r["refused"] if x[1] == "inverter-b"]
+check("a refusing B stays refused until its probe: its idle reading is not "
+      "read as taking power the other way (one refusal in 800 s)",
+      len(starts) == 1 and r["c"].inverters[1].refused == 1)
+
+# A register frozen at rest on B: refused or stale within 36 s of the ask.
+r = rig.run(2, lambda t: 2500.0 if t >= 600 else 0.0, 700.0, tick=1.0,
+            publish_s=1.0, dither=True,
+            freeze_at=lambda u: 300.0 if u == "b" else None)
+park = min([t for t, u in r["stale"] if u == "inverter-b"]
+           + [t for t, u in r["refused"] if u == "inverter-b"] or [None])
+print(f"    B's register frozen at rest from 300 s, asked at 600 s: 0 W at "
+      f"{park}")
+check("a register frozen at rest on B is caught as on A (within 36 s of "
+      "the ask)", park is not None and park - 600.0 <= 36.0)
+# At a 5 s meter the stale trip comes first: its refusal is centred too.
+saved = dict(rig.OFFSET)
+rig.OFFSET["b"] = -110.0
+try:
+    r = rig.run(2, lambda t: 2500.0 if t >= 600 else 0.0, 760.0, tick=5.0,
+                publish_s=1.0, dither=True,
+                freeze_at=lambda u: 300.0 if u == "b" else None)
+finally:
+    rig.OFFSET.clear()
+    rig.OFFSET.update(saved)
+st = [t for t, u in r["stale"] if u == "inverter-b"]
+ref = [t for t, u in r["refused"] if u == "inverter-b"]
+print(f"    the same at a 5 s meter, B idle -110 W: stale {st}, refused {ref}")
+check("...and at a 5 s meter the stale trip on B's held -110 W is a refusal "
+      "of B (one trip), not a repeating site stop",
+      len(st) == 1 and ref == st)
+
+# Review: the two centrings with no check of their own.
+# N=1, 5 s meter: the stale trip on a held -110 W idle reading is a refusal.
+saved = dict(rig.OFFSET)
+rig.OFFSET["a"] = -110.0
+try:
+    r = rig.run(1, lambda t: 2500.0 if t >= 600 else 0.0, 800.0, tick=5.0,
+                publish_s=1.0, dither=True, freeze_at=lambda u: 300.0)
+finally:
+    rig.OFFSET.clear()
+    rig.OFFSET.update(saved)
+st = [t for t, _u in r["stale"]]
+ref = [t for t, _u in r["refused"]]
+print(f"    N=1, 5 s meter, register frozen on -110 W: stale {st}, refused "
+      f"{ref}")
+check("...and at N=1 the same stale trip is a refusal (one trip), not a "
+      "repeating site stop", len(st) == 1 and ref == st)
+
+# SAFETY-42: B asked under 200 W while giving nothing (its idle reading) is
+# parked, not named as not delivering; A carries the house.
+def small_ask():
+    return rig.run(2, lambda t: 150.0, 700.0, tick=1.0, noise=4.0,
+                   store={unit_key("inverter-b", "idle_w"): -100.0},
+                   cut=lambda u, t: u == "b")["c"].inverters[1]
+
+
+b, b_old = small_ask(), without_fix(small_ask)
+check("SAFETY-42: B giving nothing at a small ask, idle -100 W, is parked "
+      "(not latched as not delivering in 700 s; with idle 0 W it is)",
+      not b.delivery_wd.tripped and b.idle.value == -100.0
+      and b_old.delivery_wd.tripped)
+
+# ============================================================================ #
+print("\n2. a healthy B with its offset is never refused or flagged")
+SHAPES = ((10.0, False), (1.0, True))
+NAMES = ("rest_step", "drain_start", "drain_charge", "reversal")
+SAVED = {"b": {unit_key("inverter-b", "idle_w"): -100.0},
+         "a": {unit_key("inverter-a", "idle_w"): -100.0}}
+bad = []
+runs = 0
+for n in (1, 2):
+    for name in NAMES:
+        for tick in (1.0, 2.0, 5.0):
+            for pub, dith in SHAPES:
+                for store in (None, SAVED["a" if n == 1 else "b"]):
+                    s, f, _r = with_offset(n, lambda: rig.counts(
+                        n, name, tick=tick, publish_s=pub, dither=dith,
+                        store=store))
+                    runs += 1
+                    if s or f:
+                        bad.append((n, name, tick, pub, bool(store), s, f))
+print(f"    {runs} runs, stale or refused: {bad}")
+check("⭐ SAFETY-94's scenarios with B's offset (N=1 and N=2, 1/2/5 s "
+      "meters, both register shapes, idle learned or restored): no stale "
+      "trip and no refusal", not bad and runs == 96)
+rev = []
+for n in (1, 2):
+    for tau in (10.0, 20.0):
+        for charge in (-1500.0, -2500.0):
+            for house in (300.0, 800.0, 2000.0):
+                x = with_offset(n, lambda: rig.run(
+                    n, rig.reversal(300.0, charge, house), 600.0, tau=tau,
+                    tick=1.0, store=SAVED["a" if n == 1 else "b"]))
+                if x["stale"] or x["refused"]:
+                    rev.append((n, tau, charge, house))
+check("⭐ a charge reversing into a discharge (lag 10 and 20 s, 1 s meter) "
+      "with B's idle reading restored is never refused or flagged",
+      not rev)
+
+# ============================================================================ #
+print("\n3. learning the idle reading")
+_t, r = caught(2, "b", 1.0)
+c = r["c"]
+check("learned during the rest: A about 0 W, B about -100 W (used: -75 W), "
+      "and saved",
+      abs(c.inverters[0].idle_w) < 5
+      and abs(c.inverters[1].idle.value + 100) < 5
+      and c.inverters[1].idle_w == -idle.IDLE_MAX_W
+      and abs(c.store.data.get(unit_key("inverter-b", "idle_w"), 0) + 100)
+      < 5)
+
+# A refusing B from the start, no rest, nothing saved: nothing to learn from.
+_t, r = caught(2, "b", 1.0, load=lambda t: 3000.0, cut_at=60.0, dur=1200.0)
+check("a battery refusing from the start teaches nothing: asked the whole "
+      "time, then held at 0 W by its refusal (none learned, none saved)",
+      r["c"].inverters[1].idle.value is None
+      and unit_key("inverter-b", "idle_w") not in r["c"].store.data)
+# ... which is why the value is saved: restored, the same battery is caught.
+t_saved, _r = caught(2, "b", 1.0, load=lambda t: 3000.0, cut_at=60.0,
+                     store=SAVED["b"])
+t_none, _r = caught(2, "b", 1.0, load=lambda t: 3000.0, cut_at=60.0)
+print(f"    refusing from the start: saved idle {t_saved} s, none {t_none}")
+check("⭐ after a restart the saved idle reading is used: a B refusing from "
+      "the start is caught in 32 s; with nothing saved it is not",
+      t_saved is not None and t_saved <= 32.0 and t_none is None)
+
+# Not learned while refused: a refusing B reading -160 W (in the band) does
+# not pull its idle reading during the 0 W its refusal holds.
+class _P(rig.Plant):
+    def advance(self, t):
+        super().advance(t)
+        for u in self.units:
+            if self.cut(u, self.t):
+                self.reg[u] = -160.0
+
+
+real_plant = rig.Plant
+rig.Plant = _P
+try:
+    _t, r = caught(2, "b", 1.0, dur=CUT + 800.0)
+finally:
+    rig.Plant = real_plant
+b = r["c"].inverters[1]
+print(f"    refusing B reading -160 W: refused at {_t} s, idle "
+      f"{b.idle.value:.1f}")
+check("⭐ not learned while refused: 800 s held at 0 W reading -160 W leaves "
+      "B's idle reading at -100 W",
+      _t is not None and b.refused and abs(b.idle.value + 100.0) < 1.0)
+
+# Not learned while control is stopped (another owner may drive the battery)
+# or while the unit's sign watchdog has latched.
+class _Stopped(app_main.Controller):
+    auto = property(lambda self: False, lambda self, v: None)
+
+
+rig.Controller = _Stopped
+try:
+    r = rig.run(2, lambda t: 0.0, 600.0, tick=1.0)
+finally:
+    rig.Controller = app_main.Controller
+r2 = rig.run(2, lambda t: 0.0, 600.0, tick=1.0,
+             store={unit_key("inverter-b", "sign_tripped"): True})
+check("not learned while control is stopped, nor on a unit whose sign "
+      "watchdog has latched (600 s at 0 W); its sibling learns",
+      all(i.idle.value is None for i in r["c"].inverters)
+      and r2["c"].inverters[1].idle.value is None
+      and r2["c"].inverters[0].idle.value is not None)
+
+# A battery capped at 150 W under a big ask is not idle.
+x = idle.IdleReading()
+for t in range(0, 3600):
+    x.observe(150.0, 2000.0, float(t), True)
+check("a reading under a command over 50 W is never a sample (a capped "
+      "battery is not idle)", x.value is None and x.w == 0.0)
+
+x = idle.IdleReading()
+for t in range(0, 239):
+    x.observe(-100.0, 10.0, float(t), True)
+first = x.value
+x.observe(-100.0, 10.0, 239.0, True)
+x.observe(-100.0, 10.0, 240.0, True)
+check("the first value needs 120 s asked ~0 and then 120 s of samples",
+      first is None and abs(x.value + 100.0) < 1e-6)
+y = idle.IdleReading()
+for t in range(0, 400):
+    y.observe(-100.0, 60.0 if t % 100 == 0 else 0.0, float(t), True)
+check("a command over 50 W restarts the quiet time (a 60 W blip every "
+      "100 s: never learned)", y.value is None)
+z = idle.IdleReading()
+for t in range(0, 400):
+    z.observe(-100.0, 0.0, float(t), False)
+check("nothing is learned while learning is not allowed (refused, stale, "
+      "tripped or stopped)", z.value is None)
+
+for t in range(240, 300):
+    x.observe(-130.0, 0.0, float(t), True)
+after_min = x.value
+for t in range(300, 240 + 3600):
+    x.observe(-130.0, 0.0, float(t), True)
+print(f"    drift -100 -> -130 W: {after_min:.1f} after 60 s, {x.value:.1f} "
+      f"after an hour")
+check("drift is followed slowly: under 2 W in the first minute, most of it "
+      "in an hour", -102.0 < after_min < -100.0 and -130 < x.value < -124)
+
+o = idle.IdleReading()
+for t in range(0, 600):
+    o.observe(-300.0, 0.0, float(t), True)
+p = idle.IdleReading()
+for t in range(0, 600):
+    p.observe(2000.0 if t < 300 else -240.0, 0.0, float(t), True)
+check("a reading beyond 250 W is not a sample (-300 W: never learned; a "
+      "register held at 2000 W then -240 W: -240 W)",
+      o.value is None and p.value is not None and abs(p.value + 240.0) < 1e-6)
+check("a saved value is clamped to 250 W, the band's centre to 75 W, and "
+      "garbage is ignored",
+      idle.IdleReading(900).value == idle.IDLE_SAMPLE_W
+      and idle.IdleReading(900).w == idle.IDLE_MAX_W
+      and idle.IdleReading(-900.0).w == -idle.IDLE_MAX_W
+      and idle.IdleReading(-60.0).w == -60.0
+      and idle.IdleReading("x").value is None
+      and idle.IdleReading(float("nan")).value is None)
+
+# ============================================================================ #
+print("\n3b. a wrong idle reading (owner, 2026-10-04: centre clamped to 75 W)")
+
+
+def wrong_idle(n, unit, err, restore):
+    """Seconds from the cut to the refusal when the idle reading is `err` W
+    off: taught wrong during the rest, or restored wrong."""
+    cu = "a" if n == 1 else unit
+    true = -100.0 if unit == "b" else 0.0
+    if restore:
+        return caught(n, unit, 1.0, store={
+            unit_key(f"inverter-{cu}", "idle_w"): true + err})[0]
+
+    class _W(rig.Plant):
+        def advance(self, t):
+            rig.OFFSET[cu] = true + (err if t < REST else 0.0)
+            super().advance(t)
+    saved, real = dict(rig.OFFSET), rig.Plant
+    rig.Plant = _W
+    try:
+        return caught(n, unit, 1.0)[0]
+    finally:
+        rig.Plant = real
+        rig.OFFSET.clear()
+        rig.OFFSET.update(saved)
+
+
+A_WRONG = {(n, e, rs): wrong_idle(n, "a", e, rs) for n in (1, 2)
+           for e, rs in ((-250.0, False), (-150.0, False), (150.0, False),
+                         (250.0, False), (-250.0, True), (200.0, True),
+                         (250.0, True))}
+print(f"    A (reads about 0 W) refusing, idle off by E: {A_WRONG}")
+check("⭐ a battery reading about 0 W while refusing is caught whatever idle "
+      "reading was learned or restored (A, E -250..+250 W, N=1 and N=2)",
+      all(v is not None and v <= 32.0 for v in A_WRONG.values()))
+check("⭐ ...including a wrong saved idle_w of +200 W on A",
+      all(A_WRONG[(n, 200.0, True)] is not None for n in (1, 2)))
+B_WRONG = {(n, e): wrong_idle(n, "b", e, False) for n in (1, 2)
+           for e in (-150.0, -50.0, 90.0)}
+print(f"    B refusing, idle taught wrong by E: {B_WRONG}")
+check("B is caught across -150..+90 W of error in its idle reading",
+      all(v is not None and v <= 32.0 for v in B_WRONG.values()))
+
+# ============================================================================ #
+print("\n4. the rules at their edges")
+
+
+class _Inv:
+    def __init__(self, idle_w):
+        self.batt, self.ref_count, self.ref_since, self.ref_sign = 0.0, 0, None, 0
+        self.ref_from, self.idle_w = None, idle_w
+
+    def standing_w(self):
+        return 800.0
+
+
+class _C:
+    _now_mono = 0.0
+
+
+def evidence(readings, idle_w):
+    c, inv = _C(), _Inv(idle_w)
+    got = []
+    for i, b in enumerate(readings):
+        c._now_mono, inv.batt = float(i), b
+        got.append(app_main.Controller._gave_nothing(c, inv))
+    return got
+
+
+flat_b = evidence([-104.0 + (i % 3) for i in range(30)], -100.0)
+flat_b0 = evidence([-104.0 + (i % 3) for i in range(30)], 0.0)
+gives = evidence([0.0] * 30, -100.0)
+takes = evidence([-200.0] * 30, -100.0)
+check("the band is centred on the idle reading: B flat at -104 W is evidence "
+      "at 22 s with idle -100 W and never with idle 0 W; reading 0 W (giving "
+      "100 W) or -200 W (taking 100 W) is not",
+      1 in flat_b and flat_b.index(1) == 22 and not any(flat_b0)
+      and not any(gives) and not any(takes))
+
+T = control.Tuning(max_w=4000.0, slew_w=400.0)
+args = dict(prev_w=1200.0, grid_w=1200.0, tuning=T,
+            sat_count=control.SETTLE_CYCLES, i_w=1200.0, refused=0,
+            gave_nothing=True)
+check("compute(): the N=1 engage is centred on idle_w (-104 W refuses with "
+      "idle -100, not with 0; -4 W refuses with idle 0, not with -150)",
+      control.compute(actual_w=-104.0, idle_w=-100.0, **args).refused == 1
+      and control.compute(actual_w=-104.0, **args).refused == 0
+      and control.compute(actual_w=-4.0, **args).refused == 1
+      and control.compute(actual_w=-4.0, idle_w=-150.0, **args).refused == 0)
+args.update(refused=-1, i_w=-1200.0, prev_w=0.0, grid_w=-1200.0)
+check("compute(): a charge refusal ends when the battery takes 100 W more "
+      "than its idle reading, not at its idle reading",
+      control.compute(actual_w=-110.0, idle_w=-100.0, **args).refused == -1
+      and control.compute(actual_w=-205.0, idle_w=-100.0, **args).refused
+      == 0
+      and control.compute(actual_w=-110.0, **args).refused == 0)
+check("the band's centre stays within 75 W of 0 W, so the band keeps 0 W "
+      "+-25 W; samples to 250 W",
+      idle.IDLE_MAX_W == 75.0 and idle.IDLE_SAMPLE_W == 250.0
+      and control.REFUSED_BELOW_W - idle.IDLE_MAX_W >= 25.0
+      and idle.IDLE_ASK_W < control.PROBE_W)
+
+print()
+if fails:
+    print(f"{len(fails)} FAILED: " + ", ".join(fails))
+    sys.exit(1)
+print("all checks passed")
@@ -1631,7 +1631,10 @@ def _sign_site(hass, store=None, **over):
                   _P(), stop=asyncio.Event())
    b = Inverter("inverter-b", setpoint_entity="number.sp_b",
                 soc_entity="sensor.soc_b", batt_entity="sensor.batt_b",
-                 max_w=B_RATING_HYPOTHESIS, store=c.store)
+                 max_w=B_RATING_HYPOTHESIS, store=c.store,
+                 # SAFETY-91: a cut-out, as rule 8 requires; without one B is
+                 # held back at its reserve and gets no share to reverse.
+                 bms_soc_floor=c.inverters[0].bms_soc_floor)
    b.dev_min, b.dev_max = -B_RATING_HYPOTHESIS, B_RATING_HYPOTHESIS
    c.inverters.append(b)
    c.auto = True
@@ -0,0 +1,271 @@
+#!/usr/bin/env python3
+"""SAFETY-94: the REAL Controller on a lagging battery whose reading is late.
+
+    python3 tools/safety94_rig.py          # prints every scenario's counts
+
+Each battery ramps at 800 W/s, then follows a first-order lag (`tau`, 10 s
+as on the SAFETY-85 rig). Its reading (register 0x0518) is published every
+10 s, at a different phase per unit, and repeats its value between publishes,
+as the live boards do. B reads 100 W below what it gives (its standby draw:
+-100 W at idle, live 2026-10-03). The meter updates every `tick` s; the add-on
+reads every 1 s and cycles on a new meter value, as `run_control()` does.
+
+A frozen register stops publishing at `freeze_at`; a refusing battery (`cut`)
+gives 0 W and reads -4 W plus its offset (B: -104 W), with `noise` W of
+seeded jitter (SAFETY-97). Uses only the Controller API release/1.0 02ed120
+has, so the same file runs on the tree before SAFETY-94.
+"""
+
+import asyncio
+import math
+import os
+import random
+import sys
+from datetime import datetime, timedelta, timezone
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+import app.main as m                                      # noqa: E402
+from app.main import Controller                           # noqa: E402
+
+BASE = datetime(2026, 10, 3, 10, 50, tzinfo=timezone.utc)   # drain from 600 s
+PUBLISH_S = 10.0
+PHASE = {"a": 6.0, "b": 1.6}       # live: A publishes at :x6, B at :x1.6
+OFFSET = {"a": 0.0, "b": -100.0}   # B's standby draw, live 2026-10-03
+CUT_W = -4.0
+LIVE = {"gain": 0.6, "slew_w": 400, "target_grid_w": -10, "deadband_w": 15,
+        "step_w": 10, "heartbeat_s": 10, "stale_input_s": 15,
+        "auto_start": True, "meter_entity": "sensor.grid",
+        "meter_source": "off"}
+MAINT = {"maintenance_enabled": True, "maintenance_start_hour": 11,
+         "maintenance_discharge_w": 2500, "maintenance_hold_min": 30}
+
+
+class _Store:
+    def __init__(self, data=None):
+        from app.store import DEFAULTS
+        self.data = dict(DEFAULTS, **(data or {}))
+
+    def set(self, k, v):
+        self.data[k] = v
+
+    def get_time(self, k):
+        v = self.data.get(k)
+        return datetime.fromisoformat(v) if v else None
+
+    def set_time(self, k, when):
+        self.data[k] = when.isoformat() if when else None
+
+
+class _Pub:
+    enabled = False
+
+    def publish(self, *a, **k):
+        pass
+
+    def close(self):
+        pass
+
+
+class Plant:
+    """The batteries, their registers and the meter, in simulated seconds."""
+
+    def __init__(self, units, load, tau, tick, soc, cut, freeze_at,
+                 publish_s=PUBLISH_S, dither=False, noise=0.0, seed=0):
+        self.units, self.load, self.tau, self.tick = units, load, tau, tick
+        self.noise, self.rng = noise, random.Random(seed)
+        self.publish_s, self.dither, self.n_pub = publish_s, dither, 0
+        self.soc_fn, self.cut, self.freeze_at = soc, cut, freeze_at
+        self.cmd = {u: 0.0 for u in units}
+        self.ramp = {u: 0.0 for u in units}
+        self.real = {u: 0.0 for u in units}
+        self.reg = {u: round(OFFSET[u]) for u in units}
+        self.grid_v = float(load(0.0))
+        self.t = 0.0
+
+    def advance(self, t):
+        """Integrate to `t` in 0.1 s steps; publish and sample on schedule."""
+        while self.t < t - 1e-9:
+            self.t = round(self.t + 0.1, 6)
+            for u in self.units:
+                want = 0.0 if self.cut(u, self.t) else self.cmd[u]
+                d = want - self.ramp[u]
+                self.ramp[u] += math.copysign(min(abs(d), 80.0), d)
+                self.real[u] += ((self.ramp[u] - self.real[u])
+                                 * (1 - math.exp(-0.1 / self.tau)))
+                frozen = (self.freeze_at is not None
+                          and self.freeze_at(u) is not None
+                          and self.t >= self.freeze_at(u))
+                ph = (self.t - PHASE[u] % self.publish_s) / self.publish_s
+                if not frozen and abs(ph - round(ph)) < 1e-6:
+                    # `dither`: the +-1 W a settled register shows (live).
+                    self.n_pub += 1
+                    jit = (self.n_pub * 7 % 3 - 1) if self.dither else 0
+                    self.reg[u] = (
+                        float(round(CUT_W + OFFSET[u] + self.rng.uniform(
+                            -self.noise, self.noise)))
+                        if self.cut(u, self.t)
+                        else float(round(self.real[u] + OFFSET[u]) + jit))
+            if abs(self.t / self.tick - round(self.t / self.tick)) < 1e-6:
+                self.grid_v = float(round(self.load(self.t)
+                                          - sum(self.real.values())))
+
+
+class _Hass:
+    def __init__(self, plant):
+        self.p = plant
+
+    async def limits(self, e):
+        return (-5000.0, 5000.0, 1.0)
+
+    async def call(self, *a):
+        return True
+
+    async def number(self, e, invert=False):
+        if e == "sensor.grid":
+            return self.p.grid_v
+        u = e[-1]
+        if e.startswith("sensor.soc"):
+            return self.p.soc_fn(u, self.p.t)
+        if e.startswith("sensor.batt"):
+            return self.p.reg[u]
+        return None
+
+    async def set_number(self, e, v):
+        self.p.cmd[e[-1]] = float(v)
+        return True
+
+
+def options(n, extra=None):
+    o = dict(LIVE)
+    if n == 1:
+        o.update({"setpoint_entity": "number.sp_a",
+                  "soc_entity": "sensor.soc_a", "batt_entity": "sensor.batt_a",
+                  "max_w": 4000, "bms_soc_floor": 10})
+    else:
+        o["inverters"] = [
+            {"name": f"inverter-{u}", "setpoint_entity": f"number.sp_{u}",
+             "soc_entity": f"sensor.soc_{u}", "batt_entity": f"sensor.batt_{u}",
+             "max_w": 2500, "bms_soc_floor": 10} for u in "ab"[:n]]
+    o.update(extra or {})
+    return o
+
+
+def run(n, load, dur, *, tau=10.0, tick=1.0, soc=None, cut=None,
+        freeze_at=None, extra=None, floor_s=15.0, publish_s=PUBLISH_S,
+        dither=False, noise=0.0, seed=0, store=None):
+    """Returns a dict: per-unit stale trips [(t, unit)], refusals
+    [(t, unit or 'site')], rows [(t, grid, {u: cmd}, {u: real}, {u: reg},
+    phases)] and the controller. `store`: saved state to start from."""
+    units = tuple("ab"[:n])
+    soc = soc or (lambda u, t: 50.0)
+    cut = cut or (lambda u, t: False)
+    plant = Plant(units, load, tau, tick, soc, cut, freeze_at, publish_s,
+                  dither, noise, seed)
+
+    async def go():
+        c = Controller(options(n, extra), _Hass(plant), _Store(store), _Pub(),
+                       stop=asyncio.Event())
+        for i in c.inverters:
+            i.dev_min, i.dev_max = -5000.0, 5000.0
+        c.auto = True
+        real_dt = m.datetime
+        clock = [0.0]
+
+        class _DT(real_dt):
+            @classmethod
+            def now(cls, tz=None):
+                return BASE + timedelta(seconds=clock[0])
+
+        m.datetime = _DT
+        out = {"stale": [], "refused": [], "rows": [], "c": c}
+        was = {i.name: False for i in c.inverters}
+        was_ref = {i.name: 0 for i in c.inverters}
+        was_site = 0
+        last_grid, last_cycle = None, None
+        try:
+            t = 0.0
+            while t < dur:
+                plant.advance(t)
+                clock[0] = t
+                await c.read_inputs(now_mono=t)
+                for i in c.inverters:
+                    if i.batt_fresh.stale and not was[i.name]:
+                        out["stale"].append((t, i.name))
+                    was[i.name] = i.batt_fresh.stale
+                cycled = (c.grid != last_grid or last_cycle is None
+                          or t - last_cycle >= floor_s)
+                if cycled:
+                    last_grid, last_cycle = c.grid, t
+                    await c.cycle()
+                # A refusal can start on a read (a gate trip) or in a cycle.
+                for i in c.inverters:
+                    if i.refused and not was_ref[i.name]:
+                        out["refused"].append((t, i.name))
+                    was_ref[i.name] = i.refused
+                if c.batt_refused and not was_site:
+                    out["refused"].append((t, "site"))
+                was_site = c.batt_refused
+                if cycled:
+                    out["rows"].append((
+                        t, plant.grid_v, dict(plant.cmd),
+                        {u: round(v) for u, v in plant.real.items()},
+                        dict(plant.reg), [mm.phase for mm in c.maints]))
+                t += 1.0
+        finally:
+            m.datetime = real_dt
+        return out
+    return asyncio.run(go())
+
+
+# --- the scenarios ---------------------------------------------------------
+def rest_then(step_at, w):
+    """A house at 0 W (the batteries rest) until `step_at`, then `w`."""
+    return lambda t: w if t >= step_at else 0.0
+
+
+def reversal(at_s, charge_w, house_w):
+    """Solar surplus (the batteries charge), then a house load from `at_s`."""
+    return lambda t: house_w if t >= at_s else charge_w
+
+
+def drain_soc(floor_at):
+    """A drains (maintenance) and reaches its floor at `floor_at`; B at 50 %."""
+    def soc(u, t):
+        if u != "a":
+            return 50.0
+        return 50.0 if t < floor_at else 10.0
+    return soc
+
+
+SCENARIOS = {
+    # first command after a long rest (the live 17:39 shape)
+    "rest_step": dict(load=rest_then(600.0, 2400.0), dur=900.0),
+    # maintenance drain starts after a rest (the live 19:00 shape)
+    "drain_start": dict(load=lambda t: 300.0, dur=900.0,
+                        extra=MAINT, soc=drain_soc(1e9)),
+    # A's drain ends and its charge starts (the live 21:21 shape)
+    "drain_charge": dict(load=lambda t: 300.0, dur=1200.0, extra=MAINT,
+                         soc=drain_soc(900.0)),
+    # a charge reverses into a discharge through the lag (SAFETY-94)
+    "reversal": dict(load=reversal(300.0, -2500.0, 800.0), dur=600.0),
+}
+
+
+def counts(n, name, **kw):
+    sc = dict(SCENARIOS[name], **kw)
+    r = run(n, **sc)
+    return len(r["stale"]), len(r["refused"]), r
+
+
+if __name__ == "__main__":
+    for n in (1, 2):
+        for name in SCENARIOS:
+            for tick in (1.0, 2.0, 5.0):
+                for pub, dith in ((10.0, False), (1.0, True)):
+                    s, f, r = counts(n, name, tick=tick, publish_s=pub,
+                                     dither=dith)
+                    print(f"N={n} {name:13s} tick {tick:.0f} s publish "
+                          f"{pub:2.0f} s{' dither' if dith else '       '}: "
+                          f"stale {s} {r['stale'][:2]}, refusals {f} "
+                          f"{r['refused'][:2]}")
Author	SHA1	Message	Date
glenn schrooyenandClaude Opus 5.5	8c6e5bca2e	Release 0.15.0: correct the SAFETY-94/97 row, add the ±170 W known issue checks / unit (pull_request) Successful in 29m6s Details infra-pin / fresh (pull_request) Successful in 1s Details Review round 1 (F1-F3) on PR #173. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-05 01:23:03 +02:00
adminandClaude Opus 5.5	f01152b113	Release 0.15.0: bump version and close the CHANGELOG section checks / unit (pull_request) Successful in 29m1s Details infra-pin / fresh (pull_request) Successful in 1s Details config.yaml version 0.14.0 -> 0.15.0 (minor: behaviour change from SAFETY-94/97, no option change). New `## 0.15.0` section with the contents since 0.14.0 (`cf705a9` #171, `3129dae` #172) and the known issues. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-05 00:48:04 +02:00
admin	3129daed62	Merge pull request 'CI-14: infra-pin to admin/goodwe 3b4ff84 (WITNESS-09)' (#172 ) from ci-14-infra-pin-3b4ff84 into release/1.0 infra-pin / fresh (push) Successful in 2s Details	2026-10-05 00:45:15 +02:00
glenn schrooyenandClaude Opus 5.5	64dddd64bf	CI-14: infra-pin to admin/goodwe 3b4ff84 (WITNESS-09) checks / unit (pull_request) Successful in 29m18s Details infra-pin / fresh (pull_request) Successful in 1s Details Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-05 00:13:01 +02:00
admin	cf705a9058	SAFETY-94 + SAFETY-97: no false stale or refusal on a lagging battery; refusals graded against each battery's idle reading (#171 ) infra-pin / fresh (push) Failing after 2s Details	2026-10-04 17:27:20 +02:00
adminandClaude Opus 5.5	7d06aa674d	SAFETY-97: centre the band on the idle reading clamped to 75 W checks / unit (pull_request) Successful in 29m26s Details infra-pin / fresh (pull_request) Failing after 2s Details Owner decision 2026-10-04 (review R1). A wrong idle reading more than about 100 W off hid every refusal on that battery. Clamped under the band, the band keeps 0 W +-25 W, so a battery reading about 0 W while refusing is caught whatever was learned or restored. Samples are still taken to 250 W. Beyond about +-170 W of idle a battery behaves as in 0.14.0. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-04 16:57:16 +02:00
adminandClaude Opus 5.5	88ebf3a5a6	SAFETY-97 review: tests for four surviving mutants checks / unit (pull_request) Successful in 28m57s Details infra-pin / fresh (pull_request) Failing after 2s Details The N=1 stale-path refusal and SAFETY-42's parked test are centred on the idle reading; learning stops while control is stopped or the sign watchdog has latched. Each had no check (review mutants X7, X8, X13, X14). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-04 14:29:27 +02:00
adminandClaude Opus 5.5	3db2b6392f	SAFETY-97: test the centred stale-path refusal (mutant S10 survived) checks / unit (pull_request) Successful in 29m7s Details infra-pin / fresh (pull_request) Failing after 1s Details At a 5 s meter a register frozen at rest on B trips the stale gate before the 12-cycle evidence; its refusal must be centred on B's idle reading, or the site stops and re-trips instead of refusing B. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019DBUfvndgHwaV339Fvd2gr	2026-10-04 13:07:06 +02:00
adminandClaude Opus 5.5	80bfc5721e	SAFETY-97: point test_safety97 at MUTATION.md; record the DC-entity option checks / unit (pull_request) Successful in 29m9s Details infra-pin / fresh (pull_request) Failing after 1s Details test_bytecode requires every suite to name MUTATION.md (CI run 1158). DECISIONS: why the integration's DC battery power entity is not the fix. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019DBUfvndgHwaV339Fvd2gr	2026-10-04 12:51:52 +02:00
adminandClaude Opus 5.5	6918e154c8	SAFETY-97: "gives nothing" is graded against each battery's idle reading checks / unit (pull_request) Failing after 29m7s Details infra-pin / fresh (pull_request) Failing after 2s Details B's power reading shows -95 to -118 W at idle (standby draw), so the \|reading\| < 100 W refusal band never held a refusing B: never at N=2, and since SAFETY-94's shared rule not at N=1 either (review F1). Each unit now learns its idle reading (app/idle.py): only while control runs, the unit is not refused/stale/tripped and its command has stayed within 50 W for 120 s; first value a 120 s mean, then a 30 min follow; samples beyond 250 W dropped, value clamped to 250 W; saved per unit and restored. The shared refusal evidence, compute()'s N=1 engage and end, the unit refusal ends, the stale-path refusal and SAFETY-42's "parked" test are centred on it. Until learned it is 0 W, the rule as it was. Refusing B caught at N=1 28/28/65 s and N=2 24/24/60 s (1/2/5 s meters), before never; refusing A unchanged. Healthy B with its offset, SAFETY-94's scenarios, 96 runs: 0 stale, 0 refused. Live replay: 0. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_019DBUfvndgHwaV339Fvd2gr	2026-10-04 12:21:24 +02:00
glenn schrooyenandClaude Opus 5.5	dd5eb6fdc8	SAFETY-94 review: tests for three surviving mutants; record two gaps checks / unit (pull_request) Successful in 28m7s Details infra-pin / fresh (pull_request) Failing after 2s Details - test_safety94 part 4: time under 250 W is not counted; a command that swaps direction every cycle is never refusal evidence; a reading moving away from the ask does not restart the evidence. These kill review mutants R1, R3 and R6, which survived the PR's tests. - DECISIONS: at N=1 a battery with B's standby offset no longer latches a refusal (SAFETY-97 now covers N=1); a part-time ask is caught after 35/d s of wall time. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-04 01:17:52 +02:00
adminandClaude Opus 5.5	6759d21ea5	SAFETY-94: a healthy battery that lags or reverses is not flagged as frozen or refusing checks / unit (pull_request) Successful in 28m10s Details infra-pin / fresh (pull_request) Failing after 2s Details The stale-reading gate counted its 35 s from the register's last change, so after a rest the first read after a new command tripped it (SAFETY-58; live 2026-10-03, four trips 1 s after the command). It now counts only the time the command asked the register to move. At N=1 the refusal engaged after 12 frozen cycles if the reading was under 100 W at that moment, which a battery reversing through its lag passes at a 1 s meter. The refusal now needs the N>1 evidence at every roster size: under 100 W, one way, for 12 cycles spanning 22 s, restarting when the reading moves 50 W towards the ask. DECISIONS/SAFETY-94-lagging-battery.md; test_safety94.py. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-04 00:15:42 +02:00
admin	02ed1200dc	Merge pull request 'Release 0.14.0' (#169 ) from release-0.14.0 into release/1.0 infra-pin / fresh (push) Successful in 1s Details checks / unit (pull_request) Successful in 27m3s Details infra-pin / fresh (pull_request) Successful in 2s Details	2026-10-03 11:29:13 +02:00
Claude	f13dab1407	Release 0.14.0: changelog review fixes checks / unit (pull_request) Successful in 26m57s Details infra-pin / fresh (pull_request) Successful in 1s Details Slew step not one house's 400 W; three two-inverter known issues, not four; commissioning reference covers a new install; SoC example holds for decimal sensors; SAFETY-95 states the jump, not the export. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-03 11:01:44 +02:00
glenn schrooyenandClaude Opus 5.5	b307db1049	Release 0.14.0: version bump and changelog checks / unit (pull_request) Successful in 27m2s Details infra-pin / fresh (pull_request) Successful in 2s Details Two inverters are now supported for maintenance and the peak guard (SAFETY-91, SAFETY-93). No option changes. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-03 10:30:25 +02:00
admin	e51e3e02b2	Merge pull request 'CI-13: infra-pin to admin/goodwe 0c04488 (FW-05, WITNESS-08)' (#168 ) from ci-13-infra-pin-0c04488 into release/1.0 infra-pin / fresh (push) Successful in 1s Details	2026-10-03 10:27:02 +02:00
glenn schrooyenandClaude Opus 5.5	69dc1f0e7b	CI: bump infra pin to 0c04488 (admin/goodwe#62 FW-05, #63 WITNESS-08) checks / unit (pull_request) Successful in 27m26s Details infra-pin / fresh (pull_request) Successful in 1s Details Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-03 09:56:36 +02:00
admin	858f77cfb5	Merge pull request 'SAFETY-93: the maintenance charge end hands back smoothly, with no grid charging at a high house' (#167 ) from safety-93-no-grid-charge-at-charge-end into release/1.0 infra-pin / fresh (push) Failing after 2s Details	2026-10-03 00:58:37 +02:00
adminandClaude Opus 5.5	214051d1a8	SAFETY-93 review: a charge that ends by a stale link or a refusal hands back smoothly too checks / unit (pull_request) Successful in 27m5s Details infra-pin / fresh (pull_request) Failing after 1s Details A battery still in CHARGE but dropped by the allocator (stale link, or a SAFETY-73 refusal contradicting its charge) left its -2000 W in the loop's start point, and B went 0 -> -1600 W in one cycle. The end is now noted after the unit claims are filed: in CHARGE, live and not contradicted. Tests: part 6 (stale link, refusal) and a spy on the guard suspension. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-03 00:10:21 +02:00
adminandClaude Opus 5.5	05eb93f139	SAFETY-93: the maintenance charge end hands back smoothly, with no grid charging at a high house checks / unit (pull_request) Successful in 26m55s Details infra-pin / fresh (pull_request) Failing after 1s Details At N>=2, when a battery's maintenance charge ended, its watts stayed in the loop's start point and landed on the other battery (B 0 -> -1600 W in one cycle, charging from the grid at a 6000 W house). On the cycle a charge ends, the loop now starts from what the others stood at plus that battery's new command. N=1 and all identity digests unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-02 22:38:42 +02:00
admin	f3e409cf76	Merge pull request 'SAFETY-91: a held battery is drawn only after the others are full' (#165 ) from safety-91-held-battery-last into release/1.0 infra-pin / fresh (push) Successful in 2s Details	2026-10-02 15:53:33 +02:00
adminandClaude Opus 5.5	4cd604afcb	SAFETY-91 review: a held-back battery is released 1 point above its reserve checks / unit (pull_request) Successful in 26m26s Details infra-pin / fresh (pull_request) Successful in 1s Details A SoC reading flipping across the reserve swapped ~1000 W between the batteries on each flip (grid +-500 W with unequal lags). Also grades next_quarter()'s staleness boundary (29.5 / 30.5 s). Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-02 14:54:20 +02:00
adminandClaude Opus 5.5	6872353e2e	SAFETY-91: a held battery is drawn only after the others are full checks / unit (pull_request) Successful in 26m19s Details infra-pin / fresh (pull_request) Successful in 1s Details At N>=2 a battery at or under its own peak reserve now weighs 0 whenever the site gives (not only for the peak), a draining battery's pin becomes a floor at its drain rate so it rises before the held one gives, and a quarter's edge is graded on the next quarter when its first telegram is late. SAFETY-25 option A stays: the held battery is still drawn once the others are full. N=1 unchanged. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>	2026-10-02 14:03:54 +02:00
admin	8c438ab2e6	Release 0.13.0 (#164 ) infra-pin / fresh (push) Successful in 2s Details checks / unit (pull_request) Successful in 25m53s Details infra-pin / fresh (pull_request) Successful in 1s Details	2026-10-02 10:04:13 +02:00