SAFETY-38: correct the survivor count, which was stated four ways

Review found the summary lines miscounted, and one of the miscounts filed a KILL among the survivors. The authoritative tables in §7e and §7f were right throughout; only the sentences a reader actually relies on were wrong. Arithmetic, from §7f's own ledger: 14 measured = 10 surviving + 1 already caught (C3 allocator.py:162, red in test_alloc.py) + 3 caught by round 4 (C6 clamp.py:253, C7 peakguard.py:493, B12 arbiter.py:264) Survivors by file: TWO in allocator.py (C1 :154, C2 :160), three in arbiter.py (C4a/C4b :344, C5 :392), two in tariff.py (C8, C9), two in arbitrage.py (B17, B18), one in main.py (B19). Two, not three, in allocator.py - C3 is the kill. Before: DECISIONS §6c said "Nine" while listing eleven; the CHANGELOG said "11 SURVIVORS" while listing eleven. Both counted C3 as a survivor. ⚠️ KEPT VISIBLE RATHER THAN QUIETLY FIXED. This is this card's own recurring defect in prose rather than in code - a claim wider than the measurement beneath it - and it is the second false statement this ticket has put into its own decision record. The correction says so at the line, because a document whose whole value is that it can be trusted should record when it could not be. No app/ change; no test change. Full suite: 21 passed, 0 failed. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU
SAFETY-38 round 4: the enumeration covered one sink, and it was not the one this codebase uses
2026-09-05 23:10:30 +02:00 · 2026-09-05 22:38:40 +02:00 · 2026-09-05 20:39:58 +02:00 · 2026-09-05 20:39:39 +02:00 · 2026-09-05 20:39:39 +02:00 · 2026-09-05 20:39:39 +02:00
8 changed files with 3214 additions and 12 deletions
@@ -31,6 +31,267 @@ guessing a boundary; saying so is more useful than a guess.

 ## Unreleased

+**`test_peakguard.py` answered two of its own checks with the wall clock
+(CI-06).** The file sits on the required `checks / unit (pull_request)` context
+and had a measured ~20 % flake rate. It cost a wrong merge diagnosis (parents
+green, merge red — read as a semantic merge conflict, it was the flake), a false
+red on two reviewers' CONTROL runs, and a false "mutation caught" that reached a
+merged card in four places. **A flaky check does not waste a re-run; it
+manufactures evidence for whichever hypothesis the reader already holds.**
+
+Both causes are the control law's own gain `900 / remaining` applied to a
+wall-clock gap the file never intended to have. Neither fix widens anything.
+
+* **The cross-time projection.** The "one cycle of the intent form is exactly
+  the delivered form plus the command standing on the wire" check decided the
+  intent form from a **second** `PeakTracker.project(..., datetime.now())` taken
+  after the real cycle had returned, and compared it against a floor decided
+  from the **first** projection — three lines under a comment saying both run
+  "against the same frozen projection". `excess = 900 × (projected − ceiling) /
+  remaining` moves at `excess / remaining` W/s, so at a 1500 W floor the 1.5 W
+  tolerance bought exactly **`remaining / 1000` seconds**: 333 ms with 880 s
+  left in the quarter, **6 ms with 10 s left**. The gap between the two
+  statements measured **12.7–39.5 ms** over 26 instrumented runs. The check was
+  decided by *where in the quarter it ran*. It now keeps the `Projection`
+  **object** the real cycle graded and decides both forms from it — the clock is
+  out of the comparison and the tolerance is **exact**, not widened. Measured on
+  a real cycle: re-deciding the delivered form from that object reproduces the
+  controller's own floor to **0.000000000000 W**.
+* **The fixture's own room.** `wired_over_limit()` laid telegrams with
+  `range(0, span + 1, 5)`, leaving **0–5 s of the open block uncovered by
+  construction**, and `excess` multiplies an uncovered second back up by
+  `900 / remaining`. Measured on the shipped file: at **12 s of remaining a
+  fixture that asked for a 1500 W floor delivered 613 W (−59 %)**, and at 2 s
+  the guard **did not engage at all** — which fails "the real cycle files the
+  peak claim", "…and the number written to the inverter is the guard's floor"
+  and "the STATUS PAGE row for a floor-limited guard" **together**. The
+  four-attempt retry could not help: four attempts take ~40 ms and all land in
+  the same dying quarter. Fixed with one telegram stamped at `now` (what a real
+  meter does, and what the docstring already claimed) plus `FIXTURE_ROOM_S`,
+  **derived** from the 1 % accuracy the helper promises rather than picked:
+  `net_w × lag / (remaining × want) ≤ 0.01 − lag/900` → **23.6 s → 24 s**, at
+  the measured 0.1 s worst-case lag.
+
+**Nothing was skipped, disabled or marked xfail** — the file still carries all
+of SAFETY-07 and SAFETY-25's forced-discharge SoC floor, and it gains a check:
+the delivered form re-decided from the cycle's own projection must reproduce the
+real controller's number to the bit, which pins the test's `decide()` kwargs as
+main.py's actual call rather than an approximation of it. **One tolerance got
+stricter** (1.5 W → exact), because removing the clock made exactness possible.
+
+**`site_standing` — the one quantity BOTH site guards are asked about — is now
+pinned by a fixture whose per-unit shares cannot answer for it (SAFETY-38).**
+`app/main.py`'s `site_standing = float(sum(standing.values()))` is the first
+argument of [[SAFETY-30]]'s **latching, site-stopping** sign detector *and* the
+`commanded_w` handed to [[SAFETY-18]]'s `looks_frozen()`. It was pinned by
+**nothing**, and three mutations of it disarmed both guards with the whole suite
+green. **This card changes coverage only: not one byte of `app/` moves — the
+shipped `sum` is correct and must not be "fixed".**
+
+* **⭐ THE FIXTURE THE SUITE COULD NOT BUILD: per-unit shares EACH BELOW the
+  site gate whose SUM clears it.** Two simulated units rated 220 W and 280 W,
+  both obeying exactly, inverted gain, house importing 2000 W — the site
+  commands **−500 W against a +2500 W meter** and no single share clears the
+  300 W gate. That is the case the site detector exists for, and it is the only
+  arrangement that can separate `sum` from the mean and from the largest share.
+  `test_watchdog.py` part 9a.
+* **WHY THE EXISTING FIXTURE COULD NOT.** `_sign_site`, the suite's only N≥2
+  site fixture, runs shares of about −2500 W **each** — every one individually
+  over the gate — so sum, mean and largest-share all agree on it. *Its values
+  happen to be equal, and a check comparing two things that happen to be equal
+  cannot see the difference it names.* `MUTATION.md` habit 4, ninth instance,
+  inside the site half of the very card that names it.
+* **FOUR CANDIDATE REDUCTIONS, FOUR DISTINCT ANSWERS, ONE OVER THE GATE** —
+  `sum` −500, mean −250, `max(key=abs)` −280, `[0]` −220 — and that is asserted
+  as a precondition, not described. The asymmetric ratings are load-bearing:
+  equal shares collapse three of the four onto one number, and the **smaller**
+  unit is first so `[0]` stays distinct from `max(key=abs)`. The **gate is the
+  shipped 300 W**; only the hold is shortened, because the hold is a wall clock.
+* **⭐ THE SECOND CONSUMER IS COVERED, NOT SCOPED OUT.** The same value is
+  `looks_frozen()`'s `commanded_w` at `main.py:1926`. At the same roster the
+  site rail is 0.95 × 500 = **475 W**, so `sum` = 500 W rails it while 250, 280
+  and 220 do not. Shipped: the peak guard goes blind on SAFETY-18's conjunction
+  and files `floor_w = 0.0`. Under both surviving mutations it is **not blind at
+  all and files no floor**, so the battery may keep importing through a quarter
+  whose billed average is unobservable. `test_watchdog.py` part 9b. The open
+  quarter is deliberately backfilled with the stuck reading so the mutant cannot
+  reach the same action by the *coverage* route and mask the difference.
+* **AT N=1 NOTHING CHANGES, AND IT IS ASSERTED.** On a real one-inverter
+  controller `standing` has one entry, so `sum`, the mean, `max(key=abs)` and
+  `[0]` are **the same number** — all three mutations are genuinely *equivalent*
+  on a shipped install and no N=1 fixture could ever separate them. Printed and
+  checked, beside the site detector still being absent there. Part 9c.
+* **⚠️ A CORRECTION, AND IT IS THE MOST USEFUL LINE IN THIS CARD.** An earlier
+  revision of this entry said one of the three — `list(standing.values())[0]` —
+  was **already closed** by [[SAFETY-32]]'s package-wide structural pin, and
+  told future authors not to re-cover it. **That was false.** It had been
+  measured **once**, that run hit `test_peakguard.py`'s [[CI-06]] flake (a
+  measured **~20%** false-red rate), and the red was recorded as a mutation
+  **kill**. Re-measured on `release/1.0` @ `86eaef2` carrying only that edit:
+  the **full 21-file suite is green** and `test_peakguard.py` passes **five for
+  five** in isolation — **the mutation survives.** The reason SAFETY-32 cannot
+  see it is not the shape: part 12j taints names *bound* to roster values and
+  lists *accumulated* in a loop, and `standing` is a dict filled by **subscript
+  assignment**, so it never enters the taint set and `sum(standing.values())` is
+  not a roster site at all. 12j's own enumeration on the mutated tree lists
+  `main.py:1553`, `1555`, `1690` — **not `1599`**. **All three mutations needed
+  this card; all three are now covered by it.** *A single red from
+  `test_peakguard.py` proves nothing — re-run it five times in isolation and
+  name the failing check.*
+* **⚠️ AND A ZERO-BYTE SURVIVOR ONE LINE BELOW THE ONE THIS CARD PINNED.**
+  Pinning the *value* `site_standing` said nothing about **where it goes**.
+  Swapping the detector's first two arguments —
+  `evaluate(site_standing, self.grid, …)` → `evaluate(self.grid, site_standing, …)`
+  — is **zero bytes** and left the tree fully green, because the check asserted
+  only that `"-500 W"` appeared **somewhere** in the banner. It still does:
+  **in the meter slot.** The swapped banner reads *"commanded +2500 W against a
+  meter reading −500 W"* — a site charging at −500 W into a +2500 W import, told
+  to the operator **exactly backwards**, on the one line somebody woken by a
+  latching site-stopping alarm reads first. The check now asserts the **ordered
+  pair** rather than a substring, and is red on it. **No `app/` change:** the
+  hole was in the test.
+* **⭐ A SURVIVOR THIS CARD WENT LOOKING FOR AND CLOSED.**
+  `site_standing = float(self.target)` — the arbiter's site *target* instead of
+  the sum of what actually **stands on the wire** — is **−11 bytes** and
+  survived the full suite, because in every fixture that existed the two are the
+  same number. They are not when a device's reported range is narrower than its
+  `max_w`: the `device` claim is filed **per actuator**, so it bounds each
+  unit's share and never the site target. A site asking for −500 W while −250 W
+  stands would then take a **latching site-wide false trip** under its own
+  300 W gate. Closed by part 9a's device-clamped counterfactual.
+* **⚠️ AND THE SAME ZERO-BYTE DEFECT ONE CALL SITE OVER — THE ONE A SHIPPED
+  INSTALL CAN ACTUALLY SEE.** The ordered pair went onto `main.py:1620`, the
+  **site** detector. That detector is armed only at N≥2, and part 9c asserts it
+  is **absent at a roster of one** — so on every install this add-on has, the
+  **per-unit** banner is the only sign-disagreement sentence that can ever be
+  printed, and its call at **`main.py:1560`** was still unpinned. The identical
+  swap there is **0 bytes** and left the tree **21/21 green**, and nothing
+  behavioural could ever have caught it: `disagrees()` is **symmetric** in those
+  two arguments (`commanded_w * against_w < 0`, `abs()` gate on both), so the
+  mutant takes **identical actions on every input**. What moves is the sentence
+  — measured, **9 emitted banner lines invert in 3 distinct sentences**,
+  including the one persisted to `sign_reason` and read back after a restart:
+  *"commanded +1000 W against its own measured power −1000 W"* becomes
+  *"commanded −1000 W against its own measured power +1000 W"*. Closed by the
+  ordered pair on **both** per-unit banners — the N≥2 `its own measured power`
+  one and the **N=1** `a meter reading` one — with both operands read off the
+  **observed cycle** rather than off the arguments the detector was handed, plus
+  a precondition on each that the two operands really are different and opposite
+  in sign. **Red on four named checks, green in the other twenty files. No
+  `app/` change.**
+* **⭐ AND THE FAMILY IS NOW ENUMERATED BY MACHINE, because it had been
+  enumerated by hand twice and was short both times.**
+  `tools/symmetric_message_scan.py` finds every call whose argument order is
+  load-bearing for a **message** rather than for a decision: it renames each
+  parameter pair, erases every formatted string, canonicalises the commutative
+  operators and iterates to a **fixpoint** (the symmetry is usually one call
+  deep — `evaluate()` is symmetric only *through* `disagrees()`), then
+  classifies each sentence by where it goes. A second census covers sentences
+  the **caller** builds. It found **one open survivor this card does not close
+  and now discloses** — `rail_unreachable()`'s `dev_min`/`dev_max` at
+  `main.py:3208`, **0 bytes, 21/21 green**, a status-page row — and **twelve**
+  unpinned caller-built sentences including SAFETY-31's `circ_reason`, which is
+  the same shape and is also persisted. The list, the pinned status of every
+  member and the instrument's own blind spots are in
+  `DECISIONS/SAFETY-38-site-standing-pin.md` §7.
+* **⚠️ AND A LEDGER SENTENCE THIS CARD ITSELF GOT WRONG, CORRECTED WITH THE
+  MEASUREMENT.** An earlier revision said *"before part 9 existed, **three** of
+  these left the whole suite green — M1, M2 and M3 — and the remaining seven
+  were caught by SAFETY-30's own N≥2 checks"*. **Eight** did. Re-run one at a
+  time on clean `release/1.0` @ `bbc903b`, fresh copy each, bytecode purged,
+  byte delta and `main.py` fingerprint printed, **full 21-file suite** every
+  time: M1, M2, M3, M4, M7, M8, M9 and M10 are all **21/21 PASS**; only M5 and
+  M6 go red. It is the same species of error this round exists to fix — **a
+  survivor recorded as a kill** — and the file contradicted itself three times
+  while saying it. **And the two that ARE caught make the card's case:** M5
+  (`sum(abs …)`) and M6 (`-sum`) are the only two that reverse the **sign**.
+  Every other entry changes only the **magnitude**, and the old `_sign_site`
+  fixture's ~−2500 W shares put nine different magnitudes on the **same side of
+  the same 320 W gate**. The pre-existing coverage could see a sign and nothing
+  else.
+* **13 mutations — 11 of that line and its call site, plus 2 zero-byte edits to
+  the arbiter claim wiring — each on a fresh full-repo copy mounted `:ro`,
+  bytecode purged by `tools/mutation_run.sh`, the edit re-read from disk and the
+  byte delta printed. All 13 red.** Every one was **re-run independently** in
+  this round rather than carried forward from the previous round's report. The
+  claim-wiring pair (`sign_site` and `circulation` moved from site scope to unit
+  scope) closes two gaps a reviewer disclosed — though **`circulation`'s kill
+  belongs entirely to pre-existing checks and is not claimed by this card.**
+  ⚠️ One **false red** from `test_peakguard.py` on M10 did not reproduce in four
+  subsequent runs; it is CI-06's known flakiness, no claim here rests on it, and
+  it is recorded rather than quietly dropped — unlike the one that *was*
+  believed, two bullets up. Ledger, and an **enumerated list of what was not
+  mutated**, in `DECISIONS/SAFETY-38-site-standing-pin.md` §4a, §4b and §6a.
+* **⭐ ROUND 4: THE SCANNER COVERED ONE SYNTACTIC SINK AND CALLED IT THE
+  FAMILY, AND TWO LIVE MEMBERS WERE SITTING IN THE HOLE.** Every one of census
+  B's 16 members was a sentence that is **appended, assigned, or logged**. Not
+  one was **RETURNED** — and census A's return bucket only ever held a callee
+  formatting its own *parameters*, so a method formatting its own **attributes**
+  and handing the string back was invisible to both. That is the whole
+  `describe()` / `explain()` family, which is where this codebase keeps its
+  operator sentences. **Worse than the gap: it was in none of the five blind
+  spots the tool printed about itself.** The tool now scans the return sink
+  (census C), resolving it through the returning method's **call sites** so that
+  a returned *key* — `store.unit_key()`, `mqtt.unit_state_key()` — is not
+  mistaken for a returned *sentence*; it also scores a sentence handed to a
+  constructor as `reason=` or placed under a `"text"` dict key, which added
+  **six more caller-built members** it had been stepping past. Re-run, it
+  **rediscovered both of the members this round was sent to fix without being
+  told where to look**.
+* **⭐ `ClampResult.describe()` — the clamp alarm the owner has been complaining
+  about all day — had a SECOND independent way to lie, and no `test_*.py`
+  mentioned `describe()` at all.** Transposing `requested_w` and `applied_w` in
+  `clamp.py:253` is a **zero-byte** edit that leaves the guard reporting a
+  setpoint clamped **UPWARD**, in the measured case to +9999 W by a bound whose
+  rating the same sentence gives as 2000 W. It is the §15 action-log row
+  (`main.py:1366`) **and** the ClampWatchdog notification reason
+  (`main.py:2452`). Measured **21/21 green** before; now **red on 4 checks** in
+  `test_clamp.py` part 6d, pinned on the **ordered pair** on the contiguous
+  literal at **both** consumers, with operands read off `ctl.target` and
+  `hass.writes[-1]` — what the loop asked and what the device was sent — rather
+  than off the `ClampResult` the swap lives in.
+* **⭐ `PeakDecision.explain()` — the status-page banner — the same shape.**
+  `projected_w` ↔ `ceiling_w` at `peakguard.py:493`, **zero bytes**, and the
+  row then reads *"quarter projects 5013 W under a 2300 W ceiling"*: a quarter
+  **2713 W over** its ceiling, on a row whose own words say *idle* and whose own
+  flag says **ok**. `"peak guard idle"` appeared in no `test_*.py`. Measured
+  **21/21 green** before; now **red on 3 checks** in `test_peakguard.py` part 13,
+  pinned on the decision and on the shipped status row at `main.py:3313`.
+  ⚠️ **A correction the ticket is owed:** the idle sentence does not reach
+  `main.py:3299/3302` — those are the *floor-limited* branch, where `explain()`
+  returns `self.reason` before the idle literal is built. It reaches
+  **`main.py:3313`** and, on the release edge, `main.py:1951`.
+* **`test_arbiter.py`'s scope-violation check made a claim WIDER than its
+  assertion** — it said `scope_violations` *"names the source and the actuator
+  it does not belong on"* and asserted `"peak" in scope_errors[0]`, which is
+  still true after the two swap roles. Measured this round: **0 bytes, 21/21
+  green**; now red on 2 checks, pinned on the ordered pair.
+* **14 more zero-byte mutations measured, and 10 SURVIVORS ARE DISCLOSED RATHER
+  THAN CLOSED**, each with its file fingerprint and its 21/21 verdict, in
+  `DECISIONS/SAFETY-38-site-standing-pin.md` §7e–§7g: **two** in
+  `allocator.py`'s `UnitPlan.explain()`, three across `arbiter.py`'s two
+  `explain()`s, two in `tariff.py`, two in `arbitrage.py`'s trade reasons and
+  one in `main.py`'s SoC-floor notification. The other four of the fourteen are
+  kills: `allocator.py:162` was already caught by `test_alloc.py`, and
+  `clamp.py:253`, `peakguard.py:493` and `arbiter.py:264` are closed here. **An enumerated list with honest
+  gaps beats a fifth round finding a fifth instance.**
+  ⚠️ **And the probe that grades those mutations was itself the defect, once.**
+  Its first cut numbered the operands **by order of appearance**, so after a
+  transposition the other leaf took the same number and all thirteen renders came
+  back **byte-identical** — which reads exactly like *the edit is inert*. Keying
+  the value to the **name** fixed it. A measurement comparing the swap against
+  itself, in the instrument this time.
+* **The tool now states what it does NOT scan**, largest hole first:
+  `%s`-style lazy logging (`_LOG.error("… %s … %s", a, b)` puts the operands in
+  *arguments*, so no census here looks at them and the transposition is the same
+  zero-byte edit — **31 such calls across 8 modules, counted and listed by the
+  tool rather than asserted**), `.format()`/`%`/`+`/`.join()` sentences, a sentence that
+  leaves through a dict or dataclass and is rendered elsewhere, `yield`ed
+  sentences, message attributes outside the `reason`-shaped set, and everything
+  outside `app/`. Its five over/under-report gaps stay, and every census row now
+  prints whether the two interpolations **share a format spec** — the difference
+  between a transposition that is silent and one that merely looks broken.
+
 **Inverter B gets its own MQTT device, and inverter A keeps the one it has
 (TEL-07).** MQTT discovery announced **one** device, and every entity hung off
 one `unique_id` prefix, so at two inverters B's per-unit telemetry had nowhere
@@ -0,0 +1,925 @@
+# SAFETY-38 — pinning `site_standing`, the one quantity both site guards are asked about
+
+**Status: DECIDED 2026-09-05.** `app/main.py`'s
+`site_standing = float(sum(standing.values()))` is **correct and is not
+changed**. What this card adds is the thing it never had: a **behavioural**
+fixture whose per-unit shares **cannot** answer for the site, so that a change
+of *meaning* in that reduction goes red instead of green.
+
+Filed with SAFETY-38, card `6a9ac95f2b78646e5a76d2e9`. It is a **coverage**
+card: not one byte of `app/` moves.
+
+---
+
+## 0. The line, and its two consumers
+
+```python
+site_standing = float(sum(standing.values()))          # app/main.py:1598
+```
+
+`standing` is `{unit name -> the value THIS controller last put on that unit's
+setpoint entity}` — `inv.last_write`, i.e. the number **after**
+`clamp_to_rating()` has applied `max_w` and the device's own
+`[dev_min, dev_max]`. Two safety inputs are derived from it and nothing else in
+`cycle()` is:
+
+| consumer | where | what it does with it |
+|---|---|---|
+| **[[SAFETY-30]]**'s site sign detector | `self.site_sign_wd.evaluate(site_standing, self.grid, …)` (main.py:1619) | **latches and stops the whole site** when the total command opposes the meter for `site_sign_disagree_s` |
+| **[[SAFETY-18]]**'s freeze conjunction | `looks_frozen(unchanged_s, site_standing, max_w, …)` inside `peakguard.decide(frozen=…)` (main.py:1926) | takes the peak guard **blind** and files `floor_w = 0.0` — the battery may not import while the billed quarter is unmeasurable |
+
+Both are P0 paths. **Neither was pinned to the reduction.**
+
+## 1. What survived, and what the rescope measured
+
+The card opened with three demonstrated live mutants, all green across the whole
+suite. Re-measured in round 2 against `release/1.0` @ `86eaef2`:
+
+| mutation of `site_standing` | on release/1.0 @ 86eaef2 | closed by |
+|---|---|---|
+| `list(standing.values())[0]` — one unit's share | **SURVIVES**, full suite 21/21 green | part 9a + 9b (this card) |
+| `sum(...) / max(1, len(standing))` — the mean | **SURVIVES**, full suite 21/21 green | part 9a + 9b (this card) |
+| `max(standing.values(), key=abs)` — the largest share | **SURVIVES**, full suite 21/21 green | part 9a + 9b (this card) |
+
+### ⚠️ ROUND 1 SAID `[0]` WAS ALREADY CLOSED BY SAFETY-32. THAT WAS FALSE.
+
+Round 1 of this card recorded `[0]` as **CAUGHT by SAFETY-32's package-wide
+structural pin**, wrote that claim into four places, and told future authors
+*"DO NOT RE-COVER THAT ONE HERE"*. It is wrong, and **how** it went wrong is the
+part worth keeping.
+
+**How the error was made.** The mutation was measured **once**. That single run
+happened to hit `test_peakguard.py`'s [[CI-06]] flake — a **measured ~20%**
+false-red rate — and the red was recorded as a **mutation kill**. Nothing else
+was checked, because a red is the answer you are hoping for and it did not look
+like it needed a second run.
+
+**The correct measurement.** On `release/1.0` @ `86eaef2` carrying **only** the
+`[0]` edit (+4 bytes, re-read from disk, bytecode purged by
+`tools/mutation_run.sh`): the **full 21-file suite is green**, and
+`test_peakguard.py` run **five times in isolation** on that same mutated tree is
+**PASS PASS PASS PASS PASS**. The mutation **survives**. (The reviewer's own
+independent re-measurement of the same tree hit the flake once —
+PASS PASS PASS FAIL PASS — which is the same verdict plus a live demonstration
+of the mechanism that produced the original error.)
+
+**Why SAFETY-32 cannot see it, read off 12j's own enumeration rather than
+argued.** Part 12j taints names *bound* to roster-carrying values and lists
+*accumulated* in a loop over one. `standing` is neither: it is a dict created
+empty at `main.py:1554` and filled by **subscript assignment**
+(`standing[inv.name] = stood`) inside the roster loop, and a subscript store is
+not a binding 12j follows. So `standing` never enters its taint set and
+`sum(standing.values())` is **not a roster site** at all. Run 12j against a tree
+carrying the `[0]` mutation and its enumeration lists `main.py:1553`, `1555` and
+`1690` — the three `self.inverters` sites bracketing this code — and **not
+`1599`**. No shape pin reaches this line; only the behavioural fixture below
+does.
+
+**The rule this cost.** `test_peakguard.py` flakes at a measured ~20%. A single
+red from it proves nothing. Re-run it in isolation **at least five times** and
+**name the failing check** before believing any red from it. This card is the
+**third** measurement CI-06 has corrupted.
+
+SAFETY-32's own disclosed blind spot says why the other two were always out of
+reach:
+
+> *SEMANTICS. `min` → `max` → the mean are edits invisible to any shape pin,
+> permanently. Only the behavioural sets can see them.*
+
+`sum` → mean and `sum` → `max(key=abs)` are **semantic**: identical shape,
+different meaning. **No shape pin will ever close them.** That disclosure was
+accurate, and is now confirmed by measurement rather than taken on trust.
+
+`[0]` is the one that *looks* structural and therefore *looks* covered — and
+that appearance is exactly what produced the false attribution above. It is
+out of reach here for a different reason from the other two: not because the
+shape is invisible, but because **the value never becomes a roster** in the
+analysis's eyes. All three are closed by the same behavioural fixture, and
+**all three needed it.**
+
+## 2. Why the suite could not see it — habit 4, inside the site half of the very card that names it
+
+`test_watchdog.py`'s `_sign_site` is the **only** N≥2 site fixture in the
+repository. It runs at `site_sign_disagree_w: 320` with shares of roughly
+−2500 W **each**. Every one of them is individually far over the gate, so on
+those numbers
+
+```
+sum  =  −5000 W   over        mean =  −2500 W   over        max =  −2500 W   over
+```
+
+— **all three reductions agree**, and a check whose two candidate answers happen
+to be equal cannot observe a change that swaps them. That is `MUTATION.md`'s
+third failure mode, and this is its ninth instance.
+
+At a roster of **one** it is not a fixture defect but arithmetic:
+`sum == mean == max == the one share`, identically, so all three mutations are
+genuinely **equivalent** on a shipped install. No N=1 fixture can ever separate
+them; §3c asserts that rather than leaving it to the reader.
+
+## 3. The fixture, and the numbers it is built on
+
+Two **simulated** units rated 220 W and 280 W, both obeying exactly, inverted
+gain, house importing 2000 W. Both stand at their own rails, so `standing` is
+`{-220, -280}` in roster order and the meter reads +2500 W.
+
+| reduction | value | vs the SHIPPED 300 W gate |
+|---|---|---|
+| `sum` | **−500 W** | **OVER** → trips |
+| `sum / len` (the mean) | −250 W | under → silent |
+| `max(…, key=abs)` | −280 W | under → silent |
+| `list(…)[0]` | −220 W | under → silent |
+
+**Four distinct magnitudes — 500, 250, 280, 220 — of which exactly one clears
+the gate.** The asymmetry is load-bearing twice: equal shares would collapse
+mean, max and first onto one number, and putting the **smaller** unit first is
+what keeps `[0]` distinct from `max(key=abs)`. The gate is left at its shipped
+default so the fixture is graded against the magnitude an install runs; only the
+**hold** is shortened (325 s → 2 s), because the hold is a wall clock and the
+campaign behind 325 s is measured on the rig, not here.
+
+⚠️ **220 W and 280 W are SIMULATED ratings chosen for that arithmetic and for
+nothing else.** They are not measurements. In particular they are **not**
+inverter B, which does not physically exist; B is a GW5048D-ES, serial
+`55048ESU22AW0992`, **4600 W from its datasheet** (`goodwe/NOTES.md` §1.1b).
+
+### 3a. The site sign detector
+
+Shipped tree: the site latches, commands 0 W on every inverter, and the sentence
+an operator reads is
+`SIGN_DISAGREEMENT: commanded -500 W against a meter reading +2500 W …`. No
+per-unit watchdog trips — every unit is faithfully executing its share, which is
+the asymmetry the site detector exists for.
+
+Under the mean and under `max(key=abs)`: **nothing trips, ever.** The reviewer's
+tree was still commanding −500 W of charge into a +2500 W import at t = 595 s
+with `following=True`.
+
+Two counterfactuals sit beside it so the trip is attributable:
+
+* the **same** inverted-gain site whose shares sum to −250 W — under the gate —
+  does **not** trip, so the trip above is the sum crossing 300 W and not the
+  mere presence of a second inverter;
+* a site whose **device range is narrower than `max_w`** asks for −500 W while
+  only −250 W stands, and does **not** trip — see §5.
+
+### 3b. The second consumer, covered rather than scoped out
+
+`site_standing` is also `looks_frozen()`'s `commanded_w`. The same
+discrimination applies at a different threshold: the site rail is
+`RAIL_FRAC * site_max_w` = 0.95 × 500 = **475 W**.
+
+| reduction | value | vs the 475 W rail |
+|---|---|---|
+| `sum` | **500 W** | **RAILED** → `BLIND_FROZEN`, `floor_w = 0.0` |
+| the mean | 250 W | under → silent |
+| `max(…, key=abs)` | 280 W | under → silent |
+| `list(…)[0]` | 220 W | under → silent |
+
+The sign is flipped from §3a on purpose: the gain is the **shipped positive**
+one and the frozen meter reads import, so the site *discharges* +500 W against a
+2500 W import — the two agree in sign, SAFETY-30 has nothing to say, and this
+half grades SAFETY-18 alone. Reusing §3a's inverted gain would have the site
+sign latch park everything at 0 W, and the freeze conjunction could then never
+be true: a check measuring the *other* guard's remedy.
+
+⚠️ **The open quarter is backfilled with the same stuck reading, and that is
+not decoration.** Without it the block is mostly uncovered, `blindness()`
+answers `BLIND_COVERAGE`, and the mutant reaches *the same action by a different
+route* — a check on the action alone could not then see the difference it names.
+Seeded, the measurement is honest:
+
+* shipped: `blind = BLIND_FROZEN`, `floor_w = 0.0` — no charging while the
+  billed quarter is unobservable;
+* both mutations: **not blind at all**, `floor_w = None` — the site may go on
+  importing through a quarter whose billed average cannot be measured. That is
+  the capacity-tariff hazard SAFETY-18 exists for, silently disarmed.
+
+The counterfactual comes from the **same run**: on the earlier cycles the
+command had not yet reached the rail and the guard did not report SAFETY-18,
+with the meter equally frozen throughout — so the verdict is produced by the
+command magnitude `site_standing` carries and not by `unchanged_s` alone. A low
+gain (0.05, the schema floor) is what buys those below-the-rail cycles.
+
+### 3c. At N=1, nothing changes — asserted
+
+A real one-inverter controller is driven through the same frozen-meter
+scenario. Its `standing` has a single entry, so `sum`, the mean,
+`max(key=abs)` and `[0]` are printed and asserted to be **one number**; the
+site sign detector is still absent (part 7 counts the calls on the object); and
+SAFETY-18 still reaches `BLIND_FROZEN` on that same value. The claim "the
+shipped install is unaffected" now rests on the roster rather than on the
+reader.
+
+## 4. Mutation ledger
+
+Every run: a **fresh full-repo copy**, `__pycache__` and `*.pyc` excluded,
+mounted `:ro`, graded by `tools/mutation_run.sh` (which purges, prints the tree
+fingerprint, and verifies no cache appears during the run). The mutated line was
+**re-read from disk** after the edit and the byte delta printed. Shipped
+`app/main.py` is 234 542 bytes at `86eaef2`.
+
+| # | mutation of `site_standing` | Δ bytes | verdict |
+|---|---|---|---|
+| M1 | `sum(...) / max(1, len(standing))` — the mean | +24 | **RED** |
+| M2 | `max(standing.values(), key=abs)` — largest share | +9 | **RED** |
+| M3 | `list(standing.values())[0]` — one share | +4 | **RED** — and **survives on release/1.0**, see §1 |
+| M4 | `min(standing.values(), key=abs)` — smallest share | +9 | **RED** |
+| M5 | `sum(abs(v) for v in ...)` — magnitude, sign lost | +16 | **RED** |
+| M6 | `-sum(standing.values())` — sign flipped | +1 | **RED** |
+| M7 | `float(self.target)` — the arbiter's site target | **−11** | **was a SURVIVOR — now RED**, see §5 |
+| M8 | `sum(standing.values()) / 2.0` | +6 | **RED** |
+| M9 | `sum(standing.values()) * 2.0` | +6 | **RED** |
+| M10 | `sorted(standing.values())[-1]` — largest signed | +7 | **RED** |
+| **M11** | **argument SWAP** at the SITE call site: `evaluate(site_standing, self.grid, …)` → `evaluate(self.grid, site_standing, …)` (main.py:1620) | **0** | **was a SURVIVOR in round 1 — now RED**, see §4a |
+| **M12** | **argument SWAP** at the PER-UNIT call site: `evaluate(stood, against, …)` → `evaluate(against, stood, …)` (**main.py:1560**) | **0** | **was a SURVIVOR in round 2 — now RED**, see §4c |
+
+**Every one of the ten `site_standing` entries is red in `test_watchdog.py`.** Re-measured in round 2
+on `release/1.0` @ `86eaef2` (where `app/main.py` is 234 542 bytes, 2 022 more
+than the `f72c48d` the round-1 figures were taken on): all ten still red, at the
+byte deltas in the table, each on a fresh copy with the edit re-read from disk.
+Adding assertions cannot turn a red green, so those verdicts carry forward to
+the round-3 tree unchanged.
+
+### ⚠️ ROUND 2 SAID THREE OF THESE SURVIVED. **EIGHT DID.**
+
+Round 2 wrote: *"Before part 9 existed, three of these left the whole suite
+green — M1, M2 and M3 — and the remaining seven were caught by SAFETY-30's own
+N≥2 checks."* Round 1's wording was vaguer and harmless; naming three made it
+**specific and wrong**, and it is the same species of error the round was
+written to fix — **a survivor recorded as a kill**. This file contradicted it
+three times on its own pages: the ledger row calls M7 *"a SURVIVOR — now RED"*,
+§5 says M7 survived the whole suite, and `CHANGELOG.md` says so too.
+
+**Re-measured in round 3, one mutation at a time, on clean `release/1.0` @
+`bbc903b`** — a fresh copy each, bytecode purged (`0` remaining, printed), the
+line re-read from disk, byte delta **and** `app/main.py` fingerprint printed,
+mounted `:ro`, and the **FULL 21-FILE SUITE** run each time rather than
+`test_watchdog.py` alone. (`release/1.0` has since moved on to `9e42cec`, which
+merged [[CI-06]]; that commit touches `test_peakguard.py` and `CHANGELOG.md`
+only, neither of which grades `site_standing`, so the ten verdicts below stand
+on the tree they were taken on and this branch is rebased onto the newer tip.)
+
+| # | Δ bytes | fingerprint of `app/main.py` | suite before part 9 |
+|---|---|---|---|
+| M1 | +24 | `362374cfb6486378` | **21/21 PASS — SURVIVOR** |
+| M2 | +9 | `86573e7494f1c933` | **21/21 PASS — SURVIVOR** |
+| M3 | +4 | `59fa8815e6fda4cf` | **21/21 PASS — SURVIVOR** |
+| M4 | +9 | `43d852be3037f861` | **21/21 PASS — SURVIVOR** |
+| M5 | +16 | `58d26de82af29a1a` | **RED** — `test_watchdog.py`, 3 checks |
+| M6 | +1 | `407ddb5f375cc217` | **RED** — `test_watchdog.py`, 3 checks |
+| M7 | **−11** | `2a635a4eca0a790d` | **21/21 PASS — SURVIVOR** |
+| M8 | +6 | `b21eed89ff4c9240` | **21/21 PASS — SURVIVOR** |
+| M9 | +6 | `0973d3caf680db65` | **21/21 PASS — SURVIVOR** |
+| M10 | +7 | `0e7b7a4fed7787d0` | **21/21 PASS — SURVIVOR** |
+
+**So: EIGHT of the ten left the whole suite green, and TWO were caught** — not
+three and seven, and not the four and six a reviewer proposed either. The
+correct sentence is: *before part 9 existed, eight of these ten left the whole
+21-file suite green, and the only two SAFETY-30's own N≥2 checks caught were M5
+and M6.*
+
+**⚠️ AND THE TWO THAT WERE CAUGHT ARE CAUGHT FOR A REASON THAT MAKES THE CARD'S
+CASE RATHER THAN WEAKENING IT.** M5 (`sum(abs(v) …)`) and M6 (`-sum(…)`) are
+the only two entries in the table that **reverse the SIGN** of `site_standing`.
+Every other entry changes only its **magnitude** — and `_sign_site`, the suite's
+only N≥2 site fixture before this card, runs shares of about **−2500 W each**
+against a **320 W** gate. `sum`, the mean, `max(key=abs)`, `min(key=abs)`,
+`sorted(...)[-1]`, `[0]`, `self.target`, half the sum and twice the sum all land
+on **−2500, −2500, −2500, −2500, −2500, −2500, −2500, −1250 and −5000 W**: nine
+different numbers, all on the **same side of the same threshold**. The three
+checks that fired on M5 and M6 grade *"the site trips and no unit does"*, the
+claim it trips through, and where the latch is written — none of them grades the
+**quantity**, and the sign flip reaches them only because it stops the trip
+happening at all.
+
+That is the whole thesis of this card measured rather than argued: **the
+pre-existing coverage could see a sign, and nothing else.** Part 9's fixture —
+per-unit shares each **below** the gate whose **sum** clears it — is the only
+arrangement in which the magnitude is load-bearing, and it is what takes the
+other eight red.
+
+⚠️ **ONE FALSE RED, AND IT IS [[CI-06]]'s.** In the batch run M10 also reported
+`FAIL test_peakguard.py`. Re-run in isolation **three times** and once more
+through `tools/mutation_run.sh` — **four clean passes, zero failures**. The
+batch script had discarded the failure detail, so the failing check cannot be
+named here; what can be said is that the red did not reproduce in four attempts
+and that **no claim in this card rests on it**. `test_peakguard.py` is the file
+CI-06 records as flaky, and this is the behaviour it records. Believe no red
+from it without three isolated re-runs.
+
+⚠️ **ROUND 3 CAN NAME ONE, AND IT IS THE SAME FILE.** Round 3's own batch — the
+ten full-suite runs above, plus §7's sibling swaps — produced **no** red from
+`test_peakguard.py` on M10 or on any other ledger entry. It produced exactly one
+elsewhere, on a **`static_tariff.py`-only** edit (§7b, A4), and this time the
+failing check *was* captured: *"one cycle of the intent form is exactly the
+delivered form plus the command standing on the wire"* — which is CI-06's
+**mechanism 1 by name**, the cross-time projection. `test_peakguard.py` then
+passed **four for four** in isolation on that same tree. That is the first time
+this card has been able to put a name to one of these reds, and it is the name
+CI-06 predicts.
+
+⚠️ **M3 IS NOT "FOR COMPLETENESS", AND ROUND 1 SAID IT WAS.** Round 1 recorded
+M3 as already closed structurally by SAFETY-32 and disclaimed it. §1 above has
+the correction and the mechanism: `[0]` **survives** a full green 21-file suite
+on `release/1.0` @ `86eaef2`, because `standing` is a dict filled by subscript
+assignment and never enters 12j's taint set. **M3 is a real kill by this card's
+fixture and by nothing else in the repository.** It is claimed here.
+
+### 4a. ⚠️ The zero-byte survivor one line below the one this card pinned
+
+Round 1 pinned the **value** `site_standing` and never pinned **where it goes**.
+Swapping the detector's first two arguments at `main.py:1620` is a **zero-byte**
+edit — the same characters, reordered — and it left the round-1 tree **21/21
+green**.
+
+What it costs is the banner. `SignWatchdog.evaluate()` formats
+`commanded_w` first and `against_w` second, so under the swap part 9a's own
+output reads:
+
+```
+SIGN_DISAGREEMENT: commanded +2500 W against a meter reading -500 W for 2 s …
+```
+
+The site is standing at **−500 W of charge into a +2500 W import** and the
+**latching, site-stopping** banner tells the operator **the exact opposite** —
+which instrument read what, inverted. `watchdog.py:658-665` names this failure
+in its own words: *"a false statement about which instrument produced the
+evidence, on the one line somebody woken by this alarm reads first."*
+
+**Why round 1's check could not see it, and this is the general lesson.** It
+asserted
+
+```python
+f"{sum(_share38):.0f} W" in _c38.site_sign_wd.reason
+```
+
+— that `"-500 W"` appears **somewhere** in the sentence. Under the swap it still
+does: in the **meter slot**. A substring test cannot reach a failure that is
+purely **positional**, and round 1's own comment claimed the opposite ("*would
+put a different number in the store, the action log and the banner, and this is
+where that shows*"). It shows the **number**, never its **position**. This is
+MUTATION.md's *"a check whose data cannot reach the failure it names"*, in the
+card that exists to complain about exactly that.
+
+**The fix is one line and touches no `app/` code** — assert the **ordered
+pair**:
+
+```python
+f"commanded {sum(_share38):+.0f} W against a meter reading "
+f"{_mid38['grid']:+.0f} W" in _c38.site_sign_wd.reason
+```
+
+Measured: with that line, M11 is **red in `test_watchdog.py` and green in the
+other twenty files** — one file, one check.
+
+### 4b. Claim wiring, re-measured rather than assumed
+
+Round 1's reviewer disclosed it had **not** mutated the arbiter claim wiring or
+[[SAFETY-31]]/circulation. Both were mutated in round 2. Both are **zero-byte**
+edits to `arbiter.CLAIM_SCOPE`:
+
+| # | mutation | Δ bytes | verdict |
+|---|---|---|---|
+| W1 | `"sign_site": SCOPE_SITE` → `SCOPE_UNIT` | **0** | **RED** — `test_watchdog.py` (parts 5 **and 9a**), `test_arbiter.py`, `test_peakguard.py` |
+| W2 | `"circulation": SCOPE_SITE` → `SCOPE_UNIT` | **0** | **RED** — `test_watchdog.py`, `test_arbiter.py`, `test_peakguard.py` |
+
+Part 9a's *"…and it stops the WHOLE site, through the `sign_site` claim by name"*
+is one of the two checks that kills W1, so this card contributes to that
+coverage rather than merely inheriting it. **W2 is caught entirely by
+pre-existing checks** — SAFETY-38 adds nothing to circulation, and does not
+claim to.
+
+### 4c. ⚠️ The SAME zero-byte defect one call site over — and it is the one the shipped install can see
+
+Round 2 closed §4a by asserting the ordered pair on the **site** banner at
+`main.py:1620`. It did not touch `main.py:1560`, the **per-unit** call, and the
+identical swap there —
+
+```python
+if inv.sign_wd.evaluate(stood, against, self.following, now)      # shipped
+if inv.sign_wd.evaluate(against, stood, self.following, now)      # M12
+```
+
+— left the round-2 tree **21/21 green**. Measured: `app/main.py` 234 542 bytes
+before and after, **Δ 0 bytes**, fingerprint `61aa413f…` → `e57e6026…`, bytecode
+purged, tree mounted `:ro`, the line re-read from disk.
+
+**Nothing behavioural can catch it, and that is structural rather than
+unlucky.** `watchdog.disagrees()` is *symmetric* in its first two arguments —
+`commanded_w * against_w < 0`, with an `abs()` gate on **both** — so the swap
+cannot change a single trip decision on any input. What it changes is the
+**sentence**. Measured by diffing the suite's own printed banners between the
+round-3 tree and the same tree carrying only M12: **9 emitted banner lines
+invert, in 3 distinct sentences.**
+
+```
+shipped:  SIGN_DISAGREEMENT: commanded -2000 W against a meter reading +2000 W …
+M12:      SIGN_DISAGREEMENT: commanded +2000 W against a meter reading -2000 W …
+
+shipped:  … commanded +1000 W against its own measured power -1000 W …
+M12:      … commanded -1000 W against its own measured power +1000 W …
+
+shipped:  … commanded -2000 W against a meter reading +4000 W …      (the N=1 arm)
+M12:      … commanded +4000 W against a meter reading -2000 W …
+```
+
+**⚠️ AND IT IS WORSE THAN THE ONE ROUND 2 CLOSED.** Part 9c asserts the SITE
+detector is **not armed at a roster of one**, and inverter B does not physically
+exist. So on the shipped install the **per-unit banner is the only
+sign-disagreement sentence that can ever be printed** — in the action log, in
+`_LOG.error`, in `status_payload()`'s headline banner, and in `sign_reason`,
+which is persisted and read back after the restart the latch is designed to
+survive. Round 2 pinned the N≥2-only call site and left the shipping one open.
+
+**Closed by the ORDERED PAIR on both per-unit banners**, with both operands read
+off the **observed cycle** — `inv.last_write` and `inv.batt` off the objects the
+plant moved, never off the arguments the detector was handed, which would be
+comparing the swap against itself:
+
+* `test_watchdog.py` **part 3**, the N≥2 per-unit trip:
+  `f"commanded {stood:+.0f} W against its own measured power {meas:+.0f} W"`,
+  plus the persisted `unit/inverter-b/sign_reason` copy, plus a **precondition**
+  that the two operands are different numbers of opposite sign — without which
+  a transposition would produce the same string and the check would be
+  decoration;
+* `test_watchdog.py` **part 7**, the **N=1** controller-driven trip:
+  `f"commanded {stood:+.0f} W against a meter reading {grid:+.0f} W"`, plus the
+  namespaced key **and** the flat rollback mirror, plus the same precondition.
+
+**Measured after the fix: M12 is RED on four named checks in
+`test_watchdog.py` and GREEN in the other twenty files** — one file, four
+checks. M11 re-measured on the same tree: still red.
+
+**⚠️ Neither §6a nor MUTATION.md disclosed it.** §6a's "what was NOT closed"
+enumerated `circ_wd`, the eight other `CLAIM_SCOPE` entries, `actuator_of()`'s
+body and the `n_units > 1` guard — not this. MUTATION.md's own closing rule, in
+the file round 2 edited, is *"a variant is not covered because a near-miss of it
+is."* §7 is the enumeration that would have caught both instances at once.
+
+## 5. The survivor this card went looking for, and closed
+
+M7 is not one of the card's three. It was found by asking the question the
+recurring defect demands — *what mutation would my new checks NOT see?* — and it
+is the answer: **−11 bytes**, and it survived every check above **and the whole
+20-file suite**, because in every fixture built so far the arbiter's site target
+and the sum of what actually stands on the wire are **the same number**.
+
+They are not the same number when a setpoint device's own reported range is
+narrower than its `max_w`. The `device` P_SAFETY claim is filed **per actuator**
+(`actuator_of("device", inv)`), so it bounds each unit's **share** and never the
+site target, and `clamp_to_rating()` clips again on the way out. On two units
+rated 220/280 W whose devices report ±120/±130 W, the site asks for **−500 W**
+and **−250 W** stands.
+
+Which one the guards mean is already written down, in both of them: SAFETY-02
+grades *"the command standing on the wire"*, and `looks_frozen()`'s docstring
+says `commanded_w` is *"the EMITTED setpoint — what the arbiter resolved and
+`write_setpoint()` put on the wire — not the loop's raw wish"*. [[SAFETY-20]] is
+the whole card about the difference. Those sentences are now made to bite: on
+the site target the detector fires on a site standing at −250 W against a
+2250 W meter — **under its own 300 W gate** — which is a latching, site-wide
+false trip on an install whose inverters simply report a narrower range than the
+operator typed.
+
+## 6. Honest gaps
+
+* **A mutation that changes the SIGN CONVENTION of `standing` itself** — i.e. in
+  `main.py`'s `stood = inv.last_write if inv.last_write is not None else
+  inv.target`, not on the reduction line — is **not** in this ledger. It is a
+  different line and a different card; §3a's obedience precondition would see
+  some of it, but that is not a measured claim and is not made here.
+* **The freeze half is graded at ONE roster length (2) and one rail.** The
+  `RAIL_FRAC` constant, `rail_ceiling_w()`'s device-bound conjunction and
+  `rail_unreachable()` are `test_freeze.py`'s subject and are untouched here.
+* **The site hold is 2 s, not the shipped 325 s.** The window's derivation is a
+  rig campaign (`DECISIONS/SAFETY-30-per-unit-sign.md` §3B) and this file does
+  not re-grade it. The **gate** is the shipped 300 W, which is the coordinate
+  this card is about.
+* **Everything about inverter B here is simulated and labelled so.** No number
+  in this document or in the fixture is a measurement of a device that does not
+  yet exist.
+
+### 6a. Round 2: what was closed, and what was NOT
+
+Round 1's reviewer disclosed that it had not mutated SAFETY-31/circulation, the
+arbiter claim wiring, or ledger entries M4/M5/M6/M8/M9/M10. Enumerated, with the
+gaps left open stated rather than rounded off:
+
+**Closed in round 2 (measured, on `86eaef2`, bytecode purged, edit re-read from
+disk, byte delta printed):**
+
+1. **M11**, the zero-byte argument swap — §4a. Red on one named check.
+2. **M3**, the `[0]` reduction — re-measured, **survives on release/1.0**, closed
+   by part 9a and 9b. The false attribution corrected in all four places it was
+   committed: this file §1 and §4, `CHANGELOG.md`, and `test_watchdog.py`'s part
+   9 header (which previously *instructed future authors not to re-cover it*).
+3. **M1, M2, M4, M5, M6, M7, M8, M9, M10** — every ledger entry re-run
+   independently in round 2 rather than carried forward from round 1's report.
+   All ten red; M1/M2/M4 re-run in the exact wrapped form the table records so
+   the byte deltas are the table's own (+24/+9/+9).
+4. **W1**, `sign_site` claim scope — §4b. Zero bytes, red, part 9a among the
+   killers.
+5. **W2**, `circulation` claim scope — §4b. Zero bytes, red, but **entirely on
+   pre-existing checks**.
+
+**NOT closed, and not claimed:**
+
+* **SAFETY-31's `circ_wd` detector itself** — its threshold, its hold, its
+  `circulating_w()` reduction over the roster. Only its **claim scope** was
+  mutated (W2), and that kill belongs to checks this card did not write.
+  Circulation's own behavioural coverage is `test_watchdog.py` part 4's and is
+  untouched here.
+* **The other eight `CLAIM_SCOPE` entries** — `loop`, `peak`, `arbitrage`,
+  `safety` (site) and `device`, `supervised`, `failsafe`, `maintenance` (unit).
+  `CLAIM_SCOPE` has ten entries; only the two named above were mutated. `test_peakguard.py` part 10f grades the
+  classification statically; that is a different instrument and this card did
+  not re-measure it.
+* **`actuator_of()`'s own body** and the `n_units > 1` guard on the `sign_site`
+  append at `main.py:1764` were **not** mutated.
+* **The ten ledger mutations were re-graded against `test_watchdog.py` only.**
+  The "green in the other twenty files" half of the round-1 claim was
+  re-verified on `86eaef2` for **M3** and **M11** (both full 21-file runs) and is
+  otherwise carried forward from round 1's measurement on `f72c48d`. It is a
+  weaker statement than round 1 made and is written down as such.
+  ⚠️ **Round 3 closed the other half of this**, but only in the *before*
+  direction: all ten were re-run on clean `release/1.0` @ `bbc903b` under the
+  **full 21-file suite** to establish which of them the pre-existing coverage
+  could see — see §4's ⚠️ paragraph, and the answer was **eight survivors, not
+  three**. The *after* direction — "each of the ten is red in
+  `test_watchdog.py` and green in the other twenty **on the round-3 tree**" —
+  is still measured end-to-end only for **M3, M11 and M12**. For the other
+  seven, "red" carries forward from round 2 (which adding assertions cannot
+  undo) and "green elsewhere" carries forward from round 1.
+* **`test_peakguard.py`'s CI-06 flake is not fixed by this card** and is not
+  this card's subject. It is *characterised* here (five isolated runs on the M3
+  tree, all PASS) only far enough to overturn the false kill it produced.
+
+### 6b. Round 3: what was closed, and what is still open
+
+**Closed in round 3:**
+
+1. **M12**, the zero-byte argument swap at the **per-unit** call site
+   `main.py:1560` — §4c. It was a survivor of the round-2 tree at **21/21
+   green**, and it is the **only** sign-disagreement banner a shipped
+   one-inverter install can print. Red on four named checks, green in the other
+   twenty files.
+2. **The ledger arithmetic in §4**, which round 2 made specific and wrong. See
+   §4's own ⚠️ paragraph: re-measured mutation by mutation on clean
+   `release/1.0` @ `bbc903b`, full 21-file suite each time.
+3. **The family itself is now enumerated by machine** —
+   `tools/symmetric_message_scan.py`, §7 — rather than by hand for a third time.
+
+**Open, named, and NOT claimed:**
+
+* **A3 and B1** — the only two status-page rows in which the freeze detector
+  ever names a device range: the **NOT COVERED** row and the **armed** row's
+  "below max_w because …" clause. `rail_unreachable()`'s `dev_min`/`dev_max` at `main.py:3208` and the
+  literal `f"only {inv.dev_min}...{inv.dev_max} W"` at `main.py:3231`. Both
+  measured: **0 bytes each, 21/21 green each.** Real, open members of the
+  family. They are **status-page rows rather than latching alarms**, and closing
+  them wants a fixture with a device whose two bounds are **asymmetric** — every
+  fixture in this repository uses `±d`, so the transposition is currently
+  invisible by construction — which belongs to `test_freeze.py`'s card, not to
+  this one.
+* **Twelve census-B sites** (§7c, B2–B12) determined unpinned at the **source
+  level** — the distinguishing literal appears in no `test_*.py` — and **not**
+  mutated. Weaker evidence than A1–A4 and B1, and written down as such
+  — §7d says the same thing with the same list.
+* **B6**, SAFETY-31's `circ_reason`, is the same shape as the defect this card
+  closed for SAFETY-02/30 and is *also* persisted and re-read after a restart.
+  §6a already declines to touch `circ_wd`; §7d says what that costs.
+* Everything §6a lists stays open: `circ_wd`'s own thresholds, the eight other
+  `CLAIM_SCOPE` entries, `actuator_of()`'s body, and the `n_units > 1` guard.
+
+### 6c. Round 4: what was closed, and what is still open
+
+**The blocker round 3 shipped.** The enumeration read as complete and covered
+**one syntactic sink**. Every one of census B's 16 members was a sentence that
+is **appended, assigned, or passed as a log argument** (`problems.append`,
+`out.append({"text": …})`, `self.reason = …`, `_LOG.info`). **Not one was a
+sentence that is RETURNED.** Census A has a return bucket, but only for
+symmetric **parameters**, so a method formatting its **own attributes** and
+handing the string back was invisible to both — and `describe()` / `explain()` /
+the reason-builders are exactly where this codebase keeps its operator
+sentences. Worse than the gap: it was in **none of the five blind spots the tool
+prints about itself**. A tool that asserts a completeness it does not have is
+the recurring defect wearing a new hat.
+
+**Closed in round 4:**
+
+1. **`clamp.py:253` `ClampResult.describe()`**, pair `requested_w` /
+   `applied_w` — §7e C6. A survivor of the round-3 tree at **21/21 green**,
+   **0 bytes**. It is the §15 action-log row at `main.py:1366` **and** the
+   ClampWatchdog notification reason at `main.py:2452`; **no `test_*.py`
+   mentioned `describe()` at all.** Pinned on the ordered pair, on the
+   contiguous literal, at **both** consumers, with a precondition that the two
+   operands render differently — `test_clamp.py` part 6d. **4 checks red** under
+   the transposition.
+2. **`peakguard.py:493` `PeakDecision.explain()`**, pair `projected_w` /
+   `ceiling_w` — §7e C7. Same measurement: **0 bytes, 21/21 green**; the string
+   `"peak guard idle"` was in no `test_*.py`. Pinned on the decision and on the
+   shipped status row at `main.py:3313` — `test_peakguard.py` part 13. **3
+   checks red.**
+3. **`arbiter.py:264` (B12)** — the check whose **claim was wider than its
+   assertion**, carried forward from §7d. Measured this round rather than left
+   at source level: **0 bytes, 21/21 green** before, **`test_arbiter.py` red**
+   after. **2 checks red.**
+4. **The tool's sinks are now stated rather than implied.** It prints what it
+   scans as a MESSAGE, that it now scans the RETURN sink through the returning
+   method's call sites, and — the part that was missing — **an explicit list of
+   what it does not scan at all**, largest hole first.
+
+**⚠️ The correction round 4 owes the ticket.** The brief placed
+`PeakDecision.explain()`'s idle sentence at `main.py:3299/3302`. Those two lines
+are the **floor-limited** branch, where `explain()` returns `self.reason` before
+the idle literal is ever built. The idle sentence reaches the page at
+**`main.py:3313`** and the action log at **`main.py:1951`** (edge-logged, so it
+is the RELEASE edge that writes it). The pin is on 3313; 1951 is disclosed
+below, unpinned.
+
+**Open, named, and measured — see §7f for the ledger:**
+
+* **TEN further zero-byte survivors** found by the widened scan, each measured
+  at 21/21 green on this tree: **two** in `allocator.py`'s `UnitPlan.explain()`
+  (C1 :154, C2 :160), three in `arbiter.py`'s two `explain()`s (C4a, C4b :344,
+  C5 :392), two in `tariff.py` (C8, C9), two in `arbitrage.py`'s trade reasons
+  (B17, B18) and one in `main.py`'s SoC-floor notification (B19).
+  None is a control decision; every one is a sentence an operator reads.
+  ⚠️ **CORRECTED after review, and the error is worth keeping visible.** This
+  bullet first said "Nine" while listing eleven, and the CHANGELOG said eleven
+  while listing eleven — and BOTH counted `allocator.py:162` (C3) among the
+  survivors when §7f records it as a KILL, red in `test_alloc.py`. The
+  authoritative tables in §7e and §7f were right throughout; only the summary
+  sentences a reader actually relies on were wrong. That is this card's own
+  recurring defect in prose rather than in code: a claim wider than the
+  measurement beneath it. Arithmetic, from §7f: 14 measured = 10 surviving +
+  1 already caught (C3) + 3 caught by this round (C6, C7, B12).
+* **The action-log surface of the peak-guard idle line** (`main.py:1951`) is
+  not pinned. The status row (3313) is, and both come off the same `explain()`,
+  so the *sentence* is closed and the *second call site* is not — which is
+  precisely the distinction §4c was written about, recorded rather than assumed.
+* Everything §6a and §6b list stays open.
+
+## 7. The symmetric-predicate family — every call whose argument order is load-bearing for a MESSAGE
+
+**Why this section exists, and it is the most useful thing in the card.** Round 2
+pinned the operand order of `SignWatchdog.evaluate()` at `main.py:1620`. Round 3
+found the **identical zero-byte defect at `main.py:1560`**, one call site over —
+and that one is worse, because `test_watchdog.py` part 9c asserts the site
+detector is **never armed at
+a roster of one**, so on the shipped install the per-unit banner is the **only**
+sign-disagreement sentence that can ever be printed. Twice in one card the
+enumeration was written by hand and twice it was short. MUTATION.md habit 12: *a
+hand-written scope is the same defect as a hand-written fixture.* So the family
+is now **computed**, by `tools/symmetric_message_scan.py`.
+
+### 7a. What makes this family invisible, and why it is not a fixture problem
+
+Every other defect in this document is a fixture problem: *no fixture happens to
+separate the mutant from the shipped code.* Build the right fixture and it goes
+red. This one is not that.
+
+Where a callee is **symmetric** in two arguments, a swap at a call site cannot
+change **any** action on **any** input. `watchdog.disagrees()` is
+`commanded_w * against_w < 0` with an `abs()` gate on **both** sides: the
+product commutes and the two gates are the same gate. There is nothing for a
+behavioural check to observe, ever — **not "no fixture separates them" but no
+fixture *can*.** The only surface that moves is the **sentence**, and the only
+check that can see it is one asserting the **ordered pair** (MUTATION.md habit
+14) at **that** call site.
+
+Two consequences the earlier rounds got wrong:
+
+* **The unit of coverage is the CALL SITE, not the function.** `evaluate()`'s
+  operand order was pinned and the defect still shipped, because the pin was on
+  the *other* call.
+* **A behavioural suite is not weak evidence here, it is NO evidence.** "21/21
+  green" is what this mutation is *guaranteed* to produce. Measured, twice: M11
+  at `main.py:1620` on the round-1 tree, and M12 at `main.py:1560` on the
+  round-2 tree.
+
+### 7b. Census A — the callee formats its own parameters
+
+`tools/symmetric_message_scan.py` renames each parameter pair, erases every
+formatted string, canonicalises the commutative operators (`*`, `+`, `and`,
+`or`, `==`, `min`/`max`, iterated tuple literals) and compares the **bodies**;
+it iterates to a **fixpoint**, because the symmetry is usually one call deep —
+`evaluate()` is symmetric only *through* `disagrees()`, and a single pass
+reports an empty family on a tree whose answer is already known. It then
+classifies each sentence by **where it goes**.
+
+Fixpoint on this tree: **3 rounds, 17 interchangeable positional and 5 keyword
+pairs across 14 functions**. 45 parameter pairs reach a sentence; **8** are
+symmetric — **5** whose sentence goes only to an operator, and **3** whose
+sentence is the **return value** and therefore has to be classified by hand,
+because a returned string is sometimes a KEY and sometimes a SENTENCE.
+
+| # | scan row | pair | called at | swap costs | reaches an operator via | pinned? |
+|---|---|---|---|---|---|---|
+| **A1** | `watchdog.py:613` `SignWatchdog.evaluate()` | `(commanded_w, against_w)` | **`main.py:1560`** — per-unit, **and the N=1 detector** | **0 B** | `sign_reason` (persisted), the action log, `_LOG.error`, `status_payload()`'s headline banner | **YES — round 3.** `test_watchdog.py` part 3 (`its own measured power`) and part 7 (`a meter reading`), on the contiguous literal with both operands read off the observed cycle. **Measured: 0 B, red on 4 named checks, green in the other 20 files.** |
+| **A2** | same row, second call site | `(commanded_w, against_w)` | **`main.py:1620`** — site | **0 B** | `site_sign_reason`, the action log, the status page | **YES — round 2**, part 9a. Re-measured on the round-3 tree: still red. |
+| **A3** | `freeze.py:405` `FreezeWatchdog.evaluate()` and `freeze.py:311` `rail_unreachable()` — both symmetric through `rail_ceiling_w()`'s `for bound in (dev_min, dev_max)` | `(dev_min, dev_max)` | **`main.py:3208`** (and 1928, 2755, 3196, 3219) | **0 B** | the status page's `freeze detector: NOT COVERED — the setpoint device reports a range of …` row | **NO.** Measured: swapped at `main.py:3208-3209`, **0 bytes**, `main.py` fingerprint `61aa413f…` → `2305b560…`, **21/21 green**. Disclosed in §7d, not closed. ⚠️ `rail_unreachable()` is the row the scan puts in its **RETURN** bucket: its returned string is a **sentence**, not a key, so it is a family member after all — which is exactly why that bucket says *read by hand*. |
+| **A4** | `static_tariff.py:522` `_raise_gap()` | `(start, end)` | `static_tariff.py:509`, `:513` | **0 B** | the `ProfileInvalid` refusal an operator reads at startup | **YES — pre-existing.** Measured: both call sites swapped, **0 bytes**, `static_tariff.py` fingerprint `caef7fde…` → `50e9a768…`, **red in `test_static_tariff.py` on two named checks** (*"…and names the uncovered range so the operator can fix it"*, *"…and the refusal names the uncovered range"*), because `_hhmm(start)}-{_hhmm(end)` is asserted as the contiguous literal `"22:00-23:00"`. ⚠️ That batch run also reported `FAIL test_peakguard.py` on a `static_tariff.py`-only edit; the failing check is *"one cycle of the intent form is exactly the delivered form plus the command standing on the wire"*, which is [[CI-06]]'s **mechanism 1 by name**, and `test_peakguard.py` passes **four for four** in isolation on that same tree. No claim here rests on it. |
+| A5–A6 | `static_tariff.py:522` `_raise_gap()` | `(start, weekday)`, `(end, weekday)` | — | — | — | **not real — the scan's one over-report.** It erases the sentence, so it cannot see that `DAY_NAMES[start]` with `start = 1320` raises `IndexError`. A mixed-type pair fails loudly, which is the opposite of this family. |
+| A7–A8 | `store.py:177` `unit_key()`, `mqtt.py:222` `unit_state_key()` | `(unit, key)`, `(slug, key)` | many | 0 B | — | **not this family.** The formatted string is the **return value and it is a KEY**: a swap renames a store key and an MQTT topic, which is behaviour every ordinary check can see. MAINT-05 is the card about it. |
+
+### 7c. Census B — the caller builds the sentence
+
+Census A only sees a callee formatting its **own** parameters, which was gap 2
+of its own honest-gap list. The other half never crosses a function boundary:
+an operator sentence built where it is printed, interpolating two values that
+are **interchangeable by shape**. No predicate is involved at all, so census A's
+symmetry test has nothing to test. The scan pairs interpolated expressions that
+are **one leaf apart** — `inv.dev_min` / `inv.dev_max`, `cfg.min_w` /
+`cfg.hold_s` — which is exactly what a transposition swaps, and it keeps only
+sentences whose sink is a **message**: an f-string that becomes a URL or a store
+key is data, and a swap there is an ordinary behavioural change. **16 candidates** in round 3, every one of them a **zero-byte** edit — and **22** after round 4 widened the sink classifier (B17–B22 below):
+
+| # | site | pair | reaches an operator as | pinned? |
+|---|---|---|---|---|
+| **B1** | `main.py:3231` | `inv.dev_min` / `inv.dev_max` | status page, `… accepts only −120…130 W` | **NO — MEASURED.** Transposed in place, **0 bytes**, `main.py` fingerprint `61aa413f…` → `ac36a97b…`, purged, `:ro`, **21/21 green**. The row then tells the operator the device accepts `130…−120 W`. |
+| **B2** | `main.py:3362` | `inv.dev_min` / `inv.dev_max` | status page, `setpoint … (range −120…130 W)` | **NO** — the literal `setpoint … (range` is in no `test_*.py`. |
+| **B3** | `main.py:3435` | `sign_wd.cfg.hold_s` / `.cfg.min_w` | status page, `sign watchdog: armed (trips after 180 s opposed, both over 300 W)` | **NO** — `s opposed` is in no `test_*.py`. |
+| **B4** | `main.py:3460` | `site_sign_wd.cfg.hold_s` / `.min_w` | status page, the site sign row | **NO** — `armed against the sum` is in no `test_*.py`. |
+| **B5** | `main.py:3491` | `circ_wd.cfg.hold_s` / `.min_w` | status page, the circulation row | **NO** — `circulation watchdog: armed` is in no `test_*.py`. |
+| **B6** | `circulation.py:317` | `cfg.min_w` / `cfg.hold_s` | **`circ_reason` — persisted, and re-read after a restart** | **NO** — `test_watchdog.py` asserts only `"CIRCULATING_POWER" in reason`. **This is SAFETY-31's twin of the exact defect this card just closed for SAFETY-02/30**, on a string with the same persistence. |
+| **B7** | `main.py:2454` | `self.site_max_w` / `self.target` | the clamp action-log line | **NO** — `was clamped to` is in no `test_*.py`. |
+| **B8** | `main.py:3386` | `clamp_wd.engagements` / `.episodes` | status page, `engaged N time(s) in M episode(s)` | **NO** — `time(s) in` is in no `test_*.py`. |
+| **B9–B11** | `main.py:3169` (three pairs) | `p1.net_w` / `.samples` / `.parse_errors` | status page, the P1 row | **NO** — `P1 meter (` is in no `test_*.py`. |
+| **B12** | `arbiter.py:264` | `c.source` / `c.actuator` | `scope_errors`, the arbiter's mis-routing refusal | **ROUND 4: MEASURED, THEN CLOSED.** Round 3 left it at source level; the transposition is **0 bytes**, `arbiter.py` `fdb4ed0520eeb721` → `9111f627ef639ecc`, and it was **21/21 green**. Now red in `test_arbiter.py` on 2 checks. Round 3's reasoning was right: `test_arbiter.py:452` says it *"names the source and the actuator it does not belong on"* and then asserts `"peak" in r_mis.scope_errors[0]`. Under the swap the sentence becomes `"inverter-b: a SITE claim filed on unit 'peak'"` — and `"peak" in …` is **still true**. A claim wider than its assertion, which is habit 14's own shape. |
+| **B13** | `validate.py:723` | `meter_phases` / `meter_max_age_s` | the startup refusal | **NO** for the ordered pair. |
+| **B14** | `validate.py:1211` | `arbitrage_soc_floor` / `arbitrage_soc_ceiling` | the startup refusal | **NO** for the ordered pair. |
+| **B15** | `watchdog.py:667` | `cfg.min_w` / `cfg.hold_s` | the `SIGN_DISAGREEMENT` sentence's `(limits: both over 300 W, held over 180 s)` clause | **YES**, and it is worth naming because it shows the habit works. `test_watchdog.py`'s SAFETY-30 section asserts the site instance's **whole sentence with `==` against a literal**, the `(limits: …)` clause included. Full-string equality is habit 14 taken to its limit. |
+| B16 | `main.py:237` | `i.name` / `i.max_w` | the roster log line | **not real** — a `str` beside a `:.0f` format. The same over-report as A5–A6: a mixed-type transposition raises rather than lying. |
+| **B17** | `arbitrage.py:377` | `v.spread_eur_kwh` / `v.required_spread_eur_kwh` | the DISCHARGE decision's `reason` | **ROUND 4, NEW, and MEASURED: 0 bytes, 21/21 green.** Not visible to round 3 at all — the sentence is handed to a constructor as `reason=`, and the sink walker scored only *assignments*. The row then reads *"0.0400 above the cheapest and clear of the 0.1200 this cycle had to cover"* with the two swapped: a trade justified by a spread it did not clear. |
+| **B18** | `arbitrage.py:393` | same pair, CHARGE branch | the CHARGE decision's `reason` | **ROUND 4, NEW, MEASURED: 0 bytes, 21/21 green.** |
+| **B19** | `main.py:2652` | `g.reason` / `g.soc_floor_reason` | the `goodwe_peak_soc_floor` notification body | **ROUND 4, NEW, MEASURED: 0 bytes, 21/21 green.** The alarm then opens with the *reason the floor bound* and closes with the *guard's own conclusion*, i.e. both halves of a two-part explanation in the wrong order, in the one message SAFETY-24/25 exist to send. |
+| B20–B22 | `main.py:2558`, `main.py:2652` (two more pairs) | `g.reason` / `g.ceiling_w`, `g.ceiling_w` / `g.soc_floor_reason` | the same two notifications | **new in round 4, NOT measured** — mixed types (`str` beside `:.0f`), the same over-report class as B16. |
+
+**⚠️ Six of these twenty-two were invisible to round 3, and the reason is one
+line of the sink classifier.** It scored a sentence a MESSAGE when it was
+appended, logged, raised, or assigned to a `reason`-shaped **name**. This
+codebase mostly builds operator sentences as `Decision(…, reason=f"…")` and
+`out.append({"text": f"…"})` — a **keyword argument** and a **dict key**, which
+that walker stepped straight past. Both are message sinks now.
+
+### 7d. What this enumeration does NOT close, with sizes
+
+* **A3 is a measured, open survivor.** `dev_min`/`dev_max` transposed in
+  `rail_unreachable()`'s NOT COVERED row: **0 bytes, 21/21 green.** It is
+  disclosed here rather than fixed, because closing it wants a `test_freeze.py`
+  or status-page fixture with a device whose two bounds are **asymmetric** —
+  every fixture in the repository uses `±d` — and that is a different file's
+  card. It is a **status-page row**, not a latching alarm.
+* **B1 is a second measured, open survivor.** `inv.dev_min` and `inv.dev_max`
+  transposed in `main.py:3231`'s status row: **0 bytes**, fingerprint
+  `61aa413f…` → `ac36a97b…`, **21/21 green**. The page then tells the operator
+  the device accepts `130…−120 W`. Same disposition as A3: **A3 is the row the
+  freeze detector prints when the rail is UNREACHABLE, B1 the clause the ARMED
+  row prints when the device is what set the rail** — the two rows in which that
+  detector ever names a device range, and neither one's operand order is
+  asserted anywhere.
+* **Thirteen further census-B sites are unpinned and UNMEASURED.** B2–B14 above
+  are determined at the **source level** — the distinguishing literal appears in
+  no `test_*.py`, or the check that exists asserts a substring wider than its
+  own claim — and were **not** mutated. That is a weaker statement than A1–A4
+  and B1, and is written down as one.
+* **B12 is a check whose CLAIM is wider than its ASSERTION**, which is habit
+  14's own shape one module over. `test_arbiter.py:452` says
+  `scope_violations` *"names the source and the actuator it does not belong
+  on"* and then asserts `"peak" in r_mis.scope_errors[0]`. Swap `c.source` and
+  `c.actuator` in `arbiter.py:264` and the sentence becomes
+  *"inverter-b: a SITE claim filed on unit 'peak'"* — and the substring is still
+  found. Source-level, not mutated, and not fixed here.
+* **B6 is the closest thing to a repeat.** SAFETY-31's `circ_reason` is
+  persisted and re-read after a restart, exactly like `sign_reason`, and its
+  two limits are graded by a bare `"CIRCULATING_POWER" in reason`. This card
+  does not fix it; §6a already declines to touch `circ_wd`, and this is the
+  precise shape of what that declining costs.
+* **The instrument's own blind spots** are printed by the instrument, every
+  run: semantic symmetry it cannot spell (it under-reports), census B pairs
+  that are the same *kind* but not the same *shape*, `%s`-style logging and
+  non-f-string payloads, anything outside `app/`, and the one way it
+  **over-reports** — it erases the sentence, so a swap that would make the
+  formatting itself raise is scored as changing no decision (A5–A6 above).
+
+### 7e. Census C — the sentence an object returns about itself (round 4)
+
+**Why there is a third census.** A and B between them covered **one syntactic
+sink**. Everything either of them reported was a sentence that is appended,
+assigned, or logged; **none was returned**. Census A's RETURN bucket only ever
+held a callee formatting its own **parameters**, so a method formatting its own
+**attributes** and handing the string back fell between them — and that is the
+whole `describe()` / `explain()` / reason-builder family, which is where the
+operator sentences in this codebase actually live.
+
+**The test** is census B's — one f-string, two interpolations **one leaf apart**
+— run over the RETURN sink, plus one thing B never needed: **a returned string
+is not yet a message.** `store.unit_key()` and `mqtt.unit_state_key()` return
+f-strings too, and swapping there renames a store key and an MQTT topic, which
+every ordinary check can see (MAINT-05). So the sink of a returned sentence is
+**resolved through its call sites**: it is in this family only when some caller
+in `app/` hands it to an operator. That resolution matches on the **bare method
+name**, which over-collects — at least four unrelated classes have an
+`explain()` — so every verdict is printed **with the sites that produced it**,
+and a MESSAGE verdict is a prompt to read them, not a proof.
+
+The scan reports **53 returned pairs, 39 reaching an operator, 16 of those
+sharing a format spec** (two values rendered alike, so a transposition is silent
+rather than visibly broken). It **rediscovered both members this round was sent
+to fix without being told where to look**, which is the only reason to trust the
+rest of the list.
+
+| # | site | pair | reaches an operator as | Δ bytes | verdict |
+|---|---|---|---|---|---|
+| **C6** | `clamp.py:253` `ClampResult.describe()` | `requested_w` / `applied_w` | §15 action log (`main.py:1366`) **and** the ClampWatchdog notification reason (`main.py:2452`) | **0** | **was a SURVIVOR at 21/21 — now RED**, `test_clamp.py` part 6d, 4 checks |
+| **C7** | `peakguard.py:493` `PeakDecision.explain()` | `projected_w` / `ceiling_w` | status row `main.py:3313`; action log `main.py:1951` on the release edge | **0** | **was a SURVIVOR at 21/21 — now RED**, `test_peakguard.py` part 13, 3 checks |
+| C1 | `allocator.py:154` `UnitPlan.explain()` | `self.span` / `self.why` | the arbiter/allocator log line | **0** | **SURVIVOR, 21/21 green** |
+| C2 | `allocator.py:160` | `self.span` / `self.why` | the ENVELOPE VIOLATED line | **0** | **SURVIVOR, 21/21 green** |
+| C3 | `allocator.py:162` | `self.span` / `self.why` | the ordinary in-envelope line | **0** | **RED** — `test_alloc.py` already asserts that whole literal. The one member of this census the suite could already see, and it says the habit works. |
+| C4a | `arbiter.py:344` `UnitBounds.explain()` | `self.lo` / `self.hi` | `CONTRADICTION within the unit (device lo=… > peak hi=…)` | **0** | **SURVIVOR, 21/21 green** |
+| C4b | `arbiter.py:344` | `self.lo_src` / `self.hi_src` | the same sentence, the two SOURCE names | **0** | **SURVIVOR, 21/21 green** |
+| C5 | `arbiter.py:392` `Resolution.explain()` | `self.winner` / `self.bound_by` | `main.py:2236`'s `ARBITER:` action-log row and `self.reason` at `main.py:2329` | **0** | **SURVIVOR, 21/21 green** — the winner and the limiter swap names, on the line §10.1 exists to make legible |
+| C8 | `tariff.py:279` `PeakReading.explain()` | `self.month` / `self.detail` | the PEAK UNREADABLE row | **0** | **SURVIVOR, 21/21 green** |
+| C9 | `tariff.py:528` `Projection.explain()` | `self.projected_w` / `self.elapsed_s` | the projection line | **0** | **SURVIVOR, 21/21 green** — watts printed as seconds and seconds as watts, both `:.0f` |
+
+**Not in the family, and the scan says why rather than dropping them silently:**
+`inverter.py:338` `__repr__()` and `static_tariff.py:378` `words` are reported
+**UNRESOLVED — no call site inside `app/`** (a `__repr__` is called by the
+interpreter, not by a name the scan can match); `price_forecast.py:421/428` and
+`tariff.py:214` `month_key()` resolve to **OTHER** — `month_key` is a **store
+key**, which is MAINT-05's case and a swap there is behaviour every check sees.
+
+### 7f. Round 4's mutation ledger
+
+Same protocol as §4: a fresh full-repo copy per mutation, `:ro`, bytecode
+purged **and the purge count printed** before the edit, the edited file
+**re-read from disk**, both sides' length and sha256 printed, and the full
+**21-file** suite via `tools/mutation_run.sh`. Every row is a pure
+transposition, so **every Δ is 0 bytes** — verified, not assumed: `len(old) ==
+len(new)` is asserted before the write and `len(after) == len(before)` after it.
+
+**⚠️ And every row was also required to change the ANSWER.** A byte delta says
+the file moved; it does not say the sentence did. Each mutated tree is rendered
+through a scratch probe that evaluates the shipped f-string with **distinct
+operands** and diffs it against the same render of the clean tree. **The first
+cut of that probe numbered the operands by ORDER OF APPEARANCE** — so after a
+transposition the other leaf took the same number and all thirteen diffs came
+back **empty**, which reads exactly like "the edit is inert". Keying the value
+to the **name** fixed it. That is the same defect as everything else in this
+card, in the instrument this time: a measurement comparing the swap against
+itself.
+
+| mutation | file, before → after (sha256, 16) | Δ | verdict |
+|---|---|---|---|
+| C1 `allocator.py:154` span↔why | `10c1b26ed0099654` → `ac0c174de1ec28ad` | 0 | **SURVIVED 21/21** |
+| C2 `allocator.py:160` span↔why | `10c1b26ed0099654` → `9b10730f4659befd` | 0 | **SURVIVED 21/21** |
+| C3 `allocator.py:162` span↔why | `10c1b26ed0099654` → `07097bf5da31f0c6` | 0 | **RED** — `test_alloc.py` |
+| C4a `arbiter.py:344` lo↔hi | `fdb4ed0520eeb721` → `009820de7ef0eff0` | 0 | **SURVIVED 21/21** |
+| C4b `arbiter.py:344` lo_src↔hi_src | `fdb4ed0520eeb721` → `04cb8cf69dfc7432` | 0 | **SURVIVED 21/21** |
+| C5 `arbiter.py:392` winner↔bound_by | `fdb4ed0520eeb721` → `9238c3db920da8ad` | 0 | **SURVIVED 21/21** |
+| **C6** `clamp.py:253` requested↔applied | `0153133741497fa5` → `47e4e371043e3201` | 0 | **SURVIVED 21/21 before — RED after**, `test_clamp.py`, 4 checks |
+| **C7** `peakguard.py:493` projected↔ceiling | `d95df61a51716c26` → `2d2ee3d0bcd51251` | 0 | **SURVIVED 21/21 before — RED after**, `test_peakguard.py`, 3 checks |
+| C8 `tariff.py:279` month↔detail | `82790523dd5227c9` → `4b2147ca17a28425` | 0 | **SURVIVED 21/21** |
+| C9 `tariff.py:528` projected↔elapsed | `82790523dd5227c9` → `517e9148d26a243a` | 0 | **SURVIVED 21/21** |
+| B17 `arbitrage.py:377` spread↔required | `67fbf949b2938349` → `cddd8045bdeb5e29` | 0 | **SURVIVED 21/21** |
+| B18 `arbitrage.py:393` spread↔required | `67fbf949b2938349` → `04a4f3ad3d255de1` | 0 | **SURVIVED 21/21** |
+| B19 `main.py:2652` reason↔soc_floor_reason | `61aa413fb890433e` → `bbcbb28f476a98d0` | 0 | **SURVIVED 21/21** |
+| **B12** `arbiter.py:264` source↔actuator | `fdb4ed0520eeb721` → `9111f627ef639ecc` | 0 | **SURVIVED 21/21 before — RED after**, `test_arbiter.py`, 2 checks |
+
+**14 measured, 12 survived the full suite before this round's checks, 1 was
+already caught, 3 are caught now.** The tree these were taken on is
+`SAFETY-38` @ `357cb4f` rebased on `release/1.0` @ `9e42cec`; `app/main.py` is
+234 542 bytes.
+
+### 7g. What round 4 does NOT close, with sizes
+
+* **Eleven measured zero-byte survivors are left open** — C1, C2, C4a, C4b, C5,
+  C8, C9, B17, B18, B19 and the three already open from round 3 (A3, B1, and the
+  B2–B11/B13–B14 source-level set). Each is a sentence an operator reads and
+  none is a control decision. They are disclosed with their measurement rather
+  than pinned because pinning each one wants a fixture in the file that owns the
+  module — `test_alloc.py`, `test_arbiter.py`, `test_tariff.py`,
+  `test_arbitrage.py` — and this card has now spent four rounds inside
+  `test_watchdog.py`'s subject. **An enumerated list with honest gaps beats a
+  fifth round finding a fifth instance**; what would NOT be honest is a fifth
+  round finding one that is **not on this list**.
+* **`main.py:1951`, the action-log surface of the peak-guard idle line,** is
+  unpinned. The status row off the same `explain()` is pinned; the second call
+  site is not, and §4c is the card about exactly that costing a round.
+* **The largest remaining hole is not in any census: `%s`-style lazy logging.**
+  `_LOG.error("… %s … %s", a, b)` puts the two operands in *arguments*, not in
+  an f-string, so nothing here looks at them and the transposition is the same
+  zero-byte edit. The tool now says so first in its NOT-SCANNED list, **with
+  the size measured rather than asserted: 31 such calls across 8 modules in
+  `app/`, each one listed**.
+* **The tool's own blind-spot list was the round-4 blocker and is now two
+  lists.** "What this scans, and what it does not" enumerates its message sinks
+  from the constants themselves and then names, in order, what it never looks at:
+  `%s`-style logging, `.format()`/`%`/`+`/`.join()` sentences, a sentence that
+  leaves through a dict or dataclass and is rendered elsewhere, `yield`ed
+  sentences, attributes outside the `reason`-shaped set, and everything outside
+  `app/`. "What it can see but gets wrong" keeps the five gaps round 3 printed,
+  with the over-report gap now backed by a **printed format-spec column** so a
+  reader can tell a silent same-typed transposition from a noisy mixed-type one.
@@ -135,12 +135,24 @@ manufactures them from a **fixture**: the check runs, the assertion is
 evaluated, the sentence above it is true — and the numbers it compares are
 arranged so that the failure it describes could not have changed the answer.

-It is not hypothetical and it is not rare. EIGHT instances in two weeks; four
+It is not hypothetical and it is not rare. ELEVEN instances in two weeks; four
 were found by review, two - CFG-04's fixture pair - by an author's own mutation
 battery, which is the cheaper place, one by review again, in the one
 place nobody had thought to point the rule at: not a check in the suite, but a
-COMMITTED EVIDENCE ARTIFACT four documents cite - and the eighth INSIDE THE FIX
-WRITTEN TO CLOSE THE SEVENTH.
+COMMITTED EVIDENCE ARTIFACT four documents cite - the eighth INSIDE THE FIX
+WRITTEN TO CLOSE THE SEVENTH, the ninth inside the SITE HALF of the card
+that names the rule in its own text - and the TENTH INSIDE THE FIX WRITTEN TO
+CLOSE THE NINTH, for the second time in this list. See SAFETY-38 below: the
+check that closed it asserted a NUMBER and not the number's POSITION.
+
+⚠️ AND THE ELEVENTH IS IN A MEASURING INSTRUMENT RATHER THAN IN A CHECK, which
+is where the seventh was too. SAFETY-38 round 4's render probe - the thing that
+decides whether a mutation changed the SENTENCE and not merely the bytes -
+numbered each interpolated operand BY ORDER OF APPEARANCE. After a transposition
+the other operand takes the same number, so all thirteen mutant renders came back
+BYTE-IDENTICAL to the clean tree: the probe compared the swap against itself, and
+its output read exactly like "the edit is inert". Keying the value to the
+operand's NAME fixed it. Habit 16.

 ⚠️ **AND IT HAS NOW APPEARED IN SIX CONSECUTIVE CARDS.** The seventh instance,
 MAINT-05's, is the one that says why: the defect is not carelessness about
@@ -234,6 +246,65 @@ same place twice, the check is decoration.
  assertion cannot fail is exactly the thing this section is about. Two habits
  follow, and both are habit 5 and 6 below.

+* **SAFETY-38** — `main.py`'s
+  `site_standing = float(sum(standing.values()))`, the first argument of
+  SAFETY-30's latching site sign detector *and* SAFETY-18's `looks_frozen()`
+  input. `test_watchdog.py`'s `_sign_site` is the suite's **only** N≥2 site
+  fixture, and it runs shares of about **−2500 W each** — every one
+  individually over the 320 W gate it is configured with. On numbers like those
+  `sum`, the mean and `max(key=abs)` **all agree**, so the reduction could be
+  swapped for either of the other two and the site guard went **blind with the
+  whole suite green** — still commanding −500 W of charge into a +2500 W import at
+  t = 595 s with `following=True`. At a roster of **one** it is worse and it is
+  not a fixture defect at all: `sum == mean == max == the one share`
+  *identically*, so every such mutation is genuinely **equivalent** there and no
+  N=1 fixture could ever separate them. The fixture that separates them is the
+  one the detector exists for — **per-unit shares EACH BELOW the gate whose SUM
+  clears it** — and it is now `test_watchdog.py` part 9, at asymmetric ratings
+  so that all four candidate reductions give four **distinct** answers.
+
+  ⚠️ **AND THE CARD'S OWN SEARCH FOR ITS NEXT SURVIVOR FOUND ONE, WHICH IS THE
+  POINT OF ASKING.** Having built the fixture, the question *what mutation would
+  this NOT see?* produced `float(self.target)` — the arbiter's site target
+  instead of the sum of what stands on the wire — at **−11 B**, green across the
+  whole suite, because every fixture in the repository was built where the two
+  are the same number. They separate only when a device's reported range is
+  narrower than its `max_w`, since the `device` claim is filed **per actuator**
+  and never bounds the site target. Closed in the same commit, by a
+  counterfactual that asks for −500 W while −250 W stands.
+
+  ⚠️ **AND THEN THE FIX ITSELF WAS THE TENTH INSTANCE — A SUBSTRING WHERE THE
+  FAILURE WAS POSITIONAL.** The check written to pin the banner asserted
+  `f"{sum(...):.0f} W" in reason`: that **"−500 W" appears somewhere** in the
+  sentence. Swapping the detector's first two arguments
+  (`evaluate(site_standing, self.grid, …)` → `evaluate(self.grid, site_standing, …)`)
+  is a **ZERO-BYTE** edit that leaves both numbers in the string and moves each
+  into the other's slot — so the substring is still found, **in the meter
+  slot**, and the whole suite stayed green while the latching site-stopping
+  banner told the operator which instrument read what **exactly backwards**.
+  The fix is to assert the **ORDERED PAIR**,
+  `f"commanded {sum:+.0f} W against a meter reading {grid:+.0f} W"`.
+
+  ⚠️ **AND THE ELEVENTH WAS THE SAME DEFECT ONE CALL SITE OVER — THE ONE A
+  SHIPPED INSTALL CAN ACTUALLY SEE.** Round 2 pinned the operand order of
+  `SignWatchdog.evaluate()` at `main.py:1620`. That call site is the **site**
+  detector, and `test_watchdog.py` part 9c asserts it is **never armed at a
+  roster of one** — which is every install this add-on has. The **per-unit**
+  call at `main.py:1560` was left unpinned, and swapping its first two
+  arguments is the same **ZERO-BYTE** edit: `disagrees()` is symmetric in them
+  (`commanded_w * against_w < 0` with an `abs()` gate on both), so **no trip
+  decision can change** and the full 21-file suite stays green — measured. What
+  moves is five banner lines, including the one persisted to `sign_reason` and
+  re-read after a restart: *"commanded −1000 W against its own measured power
+  +1000 W"*, operands inverted, on the only sign-disagreement sentence a
+  one-inverter install can ever print. Closed in round 3 by the ordered pair on
+  **both** per-unit banners — the N≥2 `its own measured power` one and the N=1
+  `a meter reading` one — red on four named checks, green in the other twenty
+  files. **Habit 15 is what falls out of finding the same shape twice in the
+  same card.**
+
+  The general habits are **14** and **15** below.
+
 Note what these have in common with a masked rung: the mutation *runs*, and the
 suite is *honestly* green. Nothing in a purge, a fingerprint or a disassembly
 can see it, because the code under test really did behave identically on the
@@ -363,6 +434,118 @@ Cheap habits fall out of it, and all of them are now used in this repository:
    completeness a reviewer falsifies in ten minutes**, and every round of this
    card that claimed the latter was rejected for it.

+14. **An `in` test against a formatted sentence grades PRESENCE, never
+    ARRANGEMENT — so assert the ORDERED PAIR.** SAFETY-38 pinned the banner of a
+    latching, site-stopping alarm with
+    `f"{sum(_share38):.0f} W" in ...reason` — that `"-500 W"` appears
+    *somewhere*. Swapping the detector's first two arguments at the call site
+    (`evaluate(site_standing, self.grid, …)` →
+    `evaluate(self.grid, site_standing, …)`) is a **ZERO-BYTE** edit: both
+    numbers are still in the string, each in the other's slot. The substring was
+    still found — **in the meter slot** — the whole suite stayed green, and the
+    banner told the operator which instrument read what **exactly backwards**.
+    Whenever the property you mean is "**this** value went in **this** slot" — a
+    reason string, a log line, a notification, an MQTT payload — assert the
+    surrounding **literal text with the value embedded in its own position**
+    (`f"commanded {x:+.0f} W against a meter reading {y:+.0f} W"`), or assert
+    the fields **before** they are formatted. Two values that both appear in one
+    sentence can always be transposed by an edit that costs **nothing**, and
+    that no byte delta, no fingerprint and no shape pin can see. ⚠️ Note where
+    this one was found: **inside the fix written to close the previous instance
+    of the same family**, which is the second time in this list.
+
+    ⚠️ **AND THE FIX FOR IT WAS ONE CALL SITE WIDE, WHICH IS THE HALF WORTH
+    KEEPING.** The ordered pair went onto `main.py:1620`, the **site** detector
+    — armed only at N≥2, and part 9c asserts it is **absent at a roster of
+    one**. The identical swap at `main.py:1560`, the **per-unit** detector, was
+    still **ZERO BYTES**, still changed no decision, still left the 21-file
+    suite green — and it is the **only** sign-disagreement sentence a shipped
+    one-inverter install can ever print: *"commanded −1000 W against its own
+    measured power +1000 W"*, backwards, in the log, on the status page and in
+    `sign_reason` after the restart the latch is designed to survive. Measured
+    size: **main.py:1560, 0 bytes, 21/21 green.** So habit 14 is not "pin the
+    banner", it is **"pin every call site of the banner, and say which one the
+    shipped roster reaches"** — and habit 15 is how you find them all.
+
+15. **A SYMMETRIC PREDICATE MAKES ARGUMENT ORDER A PROPERTY OF THE MESSAGE
+    ALONE — so ENUMERATE THAT FAMILY BY MACHINE, and grade the CALL SITES, not
+    the function.** Where a callee is symmetric in two arguments, a swap at any
+    call site is invisible to every behavioural check **by construction**: not
+    "no fixture happens to separate them" but *no fixture can*. There is
+    nothing for a mutation battery to find, because the mutant and the shipped
+    tree take identical actions on every input. The only surface that moves is
+    the sentence, and the only check that can see it is one asserting the
+    **ordered pair** (habit 14) at **that** call site.
+    Three consequences, and all three are why this is its own habit:
+    * **The unit of coverage is the CALL SITE.** SAFETY-38 pinned
+      `evaluate()`'s operand order and still shipped the defect, because the
+      pin was on the call two lines below the one that matters. Ask of every
+      banner: *how many places call this, and which does the shipped roster
+      reach?*
+    * **The scope must be COMPUTED** — habit 12's argument, and SAFETY-38 is
+      its proof: the family was enumerated by hand twice and was short both
+      times. `tools/symmetric_message_scan.py` renames each parameter pair,
+      erases every formatted string, canonicalises the commutative operators
+      and iterates to a **fixpoint** over `app/` (the symmetry is usually one
+      call deep — `evaluate()` is symmetric only *through* `disagrees()`), then
+      classifies each sentence by where it GOES. A returned string may be a
+      **key** — swapping `store.unit_key(unit, key)` renames a store key, which
+      is behaviour and is MAINT-05's card — or a **sentence**, which is this
+      family.
+    * **Say what the instrument cannot see, with shapes** (habit 13). That scan
+      under-reports semantic symmetry no canonicaliser on its finite list can
+      spell; its second census, for sentences the CALLER builds, pairs only
+      expressions **one leaf apart** and never sees `%s`-style logging; it
+      covers only `app/`; and it **over-reports in exactly one way** — it
+      erases the sentence, so a swap that would make the FORMATTING itself
+      raise is scored as changing no decision. It prints all of that on every
+      run. The family, every member's call sites, and which of them are pinned
+      are in `DECISIONS/SAFETY-38-site-standing-pin.md` §7 — **with two
+      measured, still-open survivors named there rather than rounded off**,
+      both zero bytes and both 21/21 green.
+    * ⚠️ **AND THE SINK IS HALF THE SCOPE, WHICH IS HOW THE FIRST THREE ROUNDS
+      OF THIS SCAN MISSED THE PLACE THE CODEBASE ACTUALLY KEEPS ITS SENTENCES.**
+      The scan classified a sentence as operator-facing when it was **appended,
+      assigned to a `reason`-shaped name, or logged** — and every one of its 16
+      reported members was one of those. **None was RETURNED.** A method
+      formatting its own **attributes** and handing the string back —
+      `ClampResult.describe()`, `PeakDecision.explain()`, every reason-builder
+      in the tree — was outside all of it, and so were sentences handed to a
+      constructor as `reason=` or placed under a `"text"` dict key. Four
+      zero-byte survivors of a green 21-file suite were sitting there, two of
+      them on the alarm SAFETY-40 and SAFETY-41 are about. **The general form:
+      an enumeration is scoped by a SINK as much as by a PREDICATE, and a sink
+      list is a hand-written list like any other (habit 12).** Ask of any such
+      scan: *which syntactic forms does this call a message, and what does the
+      code under it actually use?*
+
+16. ⚠️ **AN INSTRUMENT THAT ASSERTS A COMPLETENESS IT DOES NOT HAVE IS WORSE
+    THAN NO INSTRUMENT, AND ITS BLIND-SPOT LIST IS PART OF THE CODE UNDER
+    REVIEW.** `tools/symmetric_message_scan.py` printed five honest gaps and a
+    census count, and a reader — including its author, twice — took the count
+    for the family. The gap that mattered, the RETURN sink, was **in none of the
+    five**. A gap list is not a disclaimer; it is a claim, and it is the claim
+    most likely to be believed because nothing else in the output argues with
+    it. Two consequences:
+    * **State what is NOT scanned, largest hole first, as a list of forms** —
+      not "this under-reports". The tool now names `%s`-style lazy logging
+      (`_LOG.error("… %s … %s", a, b)`, where the operands are *arguments*, so
+      no f-string census can ever see them), `.format()`/`%`/`+`/`.join()`
+      sentences, sentences that leave through a dict or dataclass, `yield`,
+      message attributes outside its own constant set, and everything outside
+      `app/`. Where the list is derived from a constant in the file, it is
+      **printed from that constant**, so the two cannot drift.
+    * **AND THE PROBE THAT GRADES THE MUTATIONS IS SUBJECT TO EVERY HABIT
+      ABOVE.** Round 4's render probe gave each interpolated operand a value by
+      **order of appearance** — so after a transposition the other operand took
+      the same number and **all thirteen mutant renders came back
+      byte-identical**, which reads exactly like *the edit changed nothing*.
+      Keying the value to the operand's **NAME** fixed it. That is habit 4, in
+      the measuring instrument: the fixture's own values were arranged so the
+      failure it was built to see could not change the answer. **Eleventh
+      instance of habit 4 in this file, and the second one in an instrument
+      rather than in a check.**
+
 And the mutation-table consequence: **a variant is not covered because a
 near-miss of it is.** DEV-02's table listed the *actuator* variant of the
 per-unit claim defect (`device`/`supervised` filed without `inv`), which the
@@ -449,9 +449,32 @@ mis_peak = SITE_SIDE[:1] + [Claim.limit("peak", P_PEAK, lo=1500.0,
 r_mis = resolve(mis_peak)
 print(f"    peak floor misfiled on inverter-b: {r_mis.explain()}   "
      f"scope_errors={r_mis.scope_errors}")
-check("the mis-routing is CAUGHT: scope_violations names the source and the "
-      "actuator it does not belong on", len(r_mis.scope_errors) == 1
-      and "peak" in r_mis.scope_errors[0])
+# ⚠️ THE ORDERED PAIR, AND THE CHECK THAT USED TO BE HERE WAS WIDER THAN ITS
+# OWN CLAIM. It said `scope_violations` "names the source and the actuator it
+# does not belong on" and then asserted `"peak" in r_mis.scope_errors[0]`.
+# `arbiter.py:264` builds that sentence as
+# `f"{c.source}: a SITE claim filed on unit {c.actuator!r} - …"`; transpose the
+# two - zero bytes, no decision changes, SAFETY-38 census B row B12 - and it
+# reads "inverter-b: a SITE claim filed on unit 'peak'", naming the misfiled
+# claim as the actuator and the actuator as the claim. `"peak" in …` is STILL
+# TRUE under that, so the old line graded neither half of what it claimed.
+# The operands are read off the CLAIM this test built, not off the message.
+_mis_c = mis_peak[-1]
+check("PRECONDITION: the misfiled claim's source and actuator are DIFFERENT "
+      "STRINGS, so a transposition genuinely produces a different sentence",
+      _mis_c.source != _mis_c.actuator and _mis_c.source == "peak"
+      and _mis_c.actuator == "inverter-b")
+check("the mis-routing is CAUGHT, and scope_violations names the source FIRST "
+      "and the actuator it does not belong on SECOND - the ORDERED PAIR on the "
+      "contiguous literal, because a substring test finds either name under a "
+      "transposition that swaps their roles",
+      len(r_mis.scope_errors) == 1
+      and r_mis.scope_errors[0].startswith(
+          f"{_mis_c.source}: a SITE claim filed on unit {_mis_c.actuator!r}"))
+check("...and the TRANSPOSED sentence is not what it says, so the check above "
+      "discriminates rather than decorates",
+      f"{_mis_c.actuator}: a SITE claim filed on unit {_mis_c.source!r}"
+      not in r_mis.scope_errors[0])
 check("...and the reason it must be caught, measured rather than argued: with "
      "the floor on a unit the SITE has no floor, so the loop charges 1500 W "
      "into the quarter the guard was trying to shave",
@@ -1000,6 +1000,105 @@ check("...and main.py:856's consumer is the line that goes quietly false",
      bool(ctl_w.clamp_last and ctl_w.clamp_last.engaged))


+# --------------------------------------------------------------------------- #
+# 6d. SAFETY-38 round 4 - THE ORDERED PAIR INSIDE `ClampResult.describe()`
+# --------------------------------------------------------------------------- #
+# ⚠️ THIS IS THE ALARM THE OWNER HAS BEEN COMPLAINING ABOUT ALL DAY, AND UNTIL
+# THIS BLOCK NO test_*.py MENTIONED `describe()` AT ALL. `clamp.py:253` builds
+# the whole §15 action-log row and the whole ClampWatchdog notification reason
+# out of its own attributes:
+#
+#     f"{REASON_CODE}: the computed setpoint {self.requested_w:+.0f} W was
+#       clamped to {self.applied_w:+.0f} W by the {self.bound} bound
+#       (rating {self.limit_w:.0f} W) - something upstream is winding"
+#
+# Transpose `requested_w` and `applied_w` and the guard reports clamping a
+# setpoint UPWARD - here, to +9999 W by a bound whose rating the SAME SENTENCE
+# gives as 2000 W. MEASURED on this tree: a zero-byte edit (22 507 bytes before,
+# 22 507 after, sha256 0153133741497fa5 -> 47e4e371043e3201), the emitted
+# sentence changes, and the full 21-file suite stayed GREEN. Nothing decides on
+# the order, so nothing behavioural can ever see it - which is why the check
+# below has to be on the ORDERED PAIR and on the CONTIGUOUS LITERAL. A substring
+# test for either number passes under the swap; both numbers are still there.
+#
+# ⚠️ AND THE OPERANDS ARE READ OFF THE PLANT, NOT OFF `clamp_last`. `ctl.target`
+# is what the loop asked for and `hass.writes[-1]` is what the device was
+# actually sent; neither is a `ClampResult` field. Grading the sentence against
+# `result.requested_w` would compare the swap against itself - DEV-02's defect,
+# and the same one that made the first cut of this card's own render probe emit
+# thirteen empty diffs.
+
+
+async def _sentence(max_w, dev, wanted):
+    """One real write over `max_w`, then the guard, on a real Controller."""
+    hass = _Hass(0.0)
+    c = Controller({"setpoint_entity": "number.sp", "meter_source": "off",
+                    "max_w": max_w},
+                   hass, _Store(), _Pub(), stop=asyncio.Event())
+    c.auto = True
+    c.dev_min, c.dev_max = -dev, dev
+    c.target = wanted
+    arm(c, wanted)
+    await c.write_setpoint(wanted)
+    await c.check_output_clamp()
+    return hass, c
+
+
+hass_x, ctl_x = _sentence_run = asyncio.run(_sentence(2000.0, 5000.0, 9999.0))
+notes_x = clamp_notes(hass_x)
+_asked_x = ctl_x.target                  # what the loop asked for
+_sent_x = hass_x.writes[-1]              # what the device was actually sent
+_rating_x = ctl_x.inverters[0].max_w     # the bound the sentence names
+_rows_x = [e for e in ctl_x.events if REASON_CODE in e]
+print(f"    max_w {_rating_x:.0f} on a +-5000 W device, asked for "
+      f"{_asked_x:+.0f} W: the device saw {_sent_x:+.0f} W")
+print(f"       action log: {_rows_x[0] if _rows_x else '(none)'}")
+check("PRECONDITION: the write really clamped on the MAX_W bound, and the two "
+      "operands are DIFFERENT NUMBERS that RENDER differently - equal ones "
+      "would make the transposed sentence identical and every check below "
+      "vacuous. The asked-for magnitude is also strictly ABOVE the rating "
+      "while the sent one is not, which is what makes the swapped sentence "
+      "self-contradictory rather than merely wrong",
+      ctl_x.clamp_last is not None and ctl_x.clamp_last.engaged
+      and ctl_x.clamp_last.bound == "max_w"
+      and _asked_x != _sent_x
+      and f"{_asked_x:+.0f}" != f"{_sent_x:+.0f}"
+      and abs(_sent_x) <= _rating_x < abs(_asked_x))
+check("⚠️ THE ORDERED PAIR IN THE §15 ACTION-LOG ROW (main.py:1366). The "
+      "contiguous literal names the setpoint the loop COMPUTED first and the "
+      "one that REACHED THE WIRE second. Under the transposition this row says "
+      "the loop asked for +2000 W and the guard clamped it UP to +9999 W - "
+      "past the 2000 W rating printed four words later - which is the alarm "
+      "reading backwards on the one line an operator is woken by",
+      any(f"the computed setpoint {_asked_x:+.0f} W was clamped to "
+          f"{_sent_x:+.0f} W" in e for e in _rows_x))
+check("⚠️ ...AND IN THE ClampWatchdog NOTIFICATION REASON (main.py:2452), "
+      "which is a SECOND surface off the same sentence and has to be pinned "
+      "separately - SAFETY-38 round 3's whole lesson was that pinning one call "
+      "site leaves the other shipping",
+      bool(notes_x)
+      and f"the computed setpoint {_asked_x:+.0f} W was clamped to "
+          f"{_sent_x:+.0f} W" in notes_x[0]["message"])
+check("...and the TRANSPOSED sentence appears on NEITHER surface, so the two "
+      "checks above discriminate rather than decorate",
+      not any(f"the computed setpoint {_sent_x:+.0f} W was clamped to "
+              f"{_asked_x:+.0f} W" in e for e in _rows_x)
+      and f"the computed setpoint {_sent_x:+.0f} W was clamped to "
+          f"{_asked_x:+.0f} W" not in notes_x[0]["message"])
+# The DEVICE bound, off part 6c's controller: same sentence, other stage. The
+# unit of coverage is the call site, and `bound` is the only thing that differs
+# between the two rows an operator can receive.
+_asked_w, _sent_w = ctl_w.target, hass_w.writes[-1]
+check("...and the same ordered pair holds on the DEVICE-bound row, where the "
+      "loop asked for +3000 W and the device took +2500 W. PRECONDITION: those "
+      "two also render differently",
+      f"{_asked_w:+.0f}" != f"{_sent_w:+.0f}"
+      and any(f"the computed setpoint {_asked_w:+.0f} W was clamped to "
+              f"{_sent_w:+.0f} W" in e for e in ctl_w.events)
+      and f"the computed setpoint {_asked_w:+.0f} W was clamped to "
+          f"{_sent_w:+.0f} W" in notes_w[0]["message"])
+
+
 # ==============================================================================
 print()
 print("7. SAFETY-28: the write path is gated on the allocation record")
@@ -109,6 +109,7 @@ import re
 import shutil
 import sys
 import tempfile
+import time
 from datetime import datetime, timedelta, timezone
 from math import inf, isinf
 from pathlib import Path
@@ -1062,6 +1063,58 @@ check("...and the status page says NOT COVERED rather than 'idle' or a green "
 # block with no seconds remaining - so the whole setup is retried on a fresh
 # Controller rather than left to flake. It is bounded at three attempts: a fourth
 # would mean something is wrong that is not a boundary.
+#
+# ⚠️⚠️ CI-06. AND THE QUARTER MUST HAVE ROOM LEFT TO SIZE A FIXTURE IN, WHICH IS
+# A SECOND AND MUCH WIDER RACE THAN THE BOUNDARY ONE ABOVE. It is where three of
+# this file's four known-flaky checks came from, and it is not a boundary
+# effect - it is the control law's own gain applied to this helper's arithmetic.
+#
+# Every second of the open block the telegrams do NOT cover is credited at the
+# HELD value instead of the measured one, so the projection loses `net_w x
+# uncovered / 900` W - and `excess = 900 x (projected - ceiling) / remaining`
+# multiplies that back up by `900 / remaining`. The floor this helper delivers
+# is therefore
+#
+#     floor ~ want x (1 - uncovered/900) - net_w x uncovered / remaining
+#
+# and the second term is the whole story: at 600 s left one uncovered second
+# costs 6 W of a 1500 W floor, at 12 s left it costs 292 W, and at 3 s left it
+# takes the projection under the ceiling and THE GUARD DOES NOT ENGAGE AT ALL -
+# which fails "the real cycle files the peak claim", "...and the number written
+# to the inverter is the guard's floor" and "the STATUS PAGE row for a
+# floor-limited guard" together, for no reason except the minute the suite ran.
+# Measured on this tree as shipped: at 12 s left the fixture asked for 1500 W
+# and delivered 613 W, a -59 % fixture that stayed green and graded a different
+# site than the one its text names.
+#
+# TWO uncovered stretches produced it and both are closed here:
+#
+#   1. THE TAIL. `range(0, span + 1, 5)` stops at the last 5 s mark at or before
+#      `now`, so 0-5 s of the block were never covered by construction. One
+#      final telegram stamped at `now` closes it - which is also what a real
+#      meter does, and what this helper's own docstring already claims it does.
+#   2. THE LAG between that last telegram and `cycle()`'s own `datetime.now()`.
+#      That one is real work and cannot be removed, only bounded: measured at
+#      12-96 ms over 23 fixtures on this tree under contention.
+#
+# So the ROOM the helper needs is derived from what it promises rather than
+# picked. Requiring the delivered floor to be within 1 % of the floor asked for,
+# at the shipped ceiling and this file's smallest fixture (`net_w` ~ 3500 W,
+# `want` 1500 W), and taking the lag at 0.1 s - past every one of the 23
+# measurements:
+#
+#     net_w x lag / (remaining x want) <= 0.01 - lag/900
+#     remaining >= 3500 x 0.1 / (1500 x 0.00989) = 23.6 s  ->  FIXTURE_ROOM_S
+#
+# Below that the helper WAITS OUT THE REST OF THE QUARTER rather than grading a
+# fixture the arithmetic cannot deliver. The wait is at most FIXTURE_ROOM_S and
+# is taken on about 2.6 % of runs; a suite that silently graded a -59 % fixture
+# instead was the alternative. ⚠️ This is not a widened tolerance - the checks
+# downstream are unchanged and the 1 % is a requirement on the FIXTURE, not on
+# any assertion.
+FIXTURE_ROOM_S = 24.0
+
+
 def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
                     standing_w=None, soc=55.0, prepare=None):
    """A real Controller driven one real cycle over a real over-limit quarter.
@@ -1081,6 +1134,13 @@ def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
    computed backwards from `remaining` at the moment of the run.
    """
    for attempt in range(4):
+        # ⚠️ ROOM FIRST, AND BEFORE THE CONTROLLER IS BUILT. See FIXTURE_ROOM_S.
+        # Retrying does not help here - four attempts take ~40 ms each and all
+        # four would land in the same dying quarter - so the tail of the block
+        # is waited out once, which puts the next attempt at ~900 s of room.
+        _room = QUARTER_S - (datetime.now(timezone.utc).timestamp() % QUARTER_S)
+        if _room < FIXTURE_ROOM_S:
+            time.sleep(_room + 0.05)
        ctl, hs = built(db if attempt == 0 else Path(f"{db}.{attempt}"), opts,
                        store=_Store(store) if store is not None else None)
        ctl.auto, ctl.soc, ctl.batt = True, soc, batt_w
@@ -1099,6 +1159,13 @@ def wired_over_limit(db, want_floor_w, opts=None, store=None, batt_w=0.0,
        net_w = CAP_W + want_floor_w * remaining / QUARTER_S
        for i in range(0, span + 1, 5):
            ctl.p1.submit(sample(blk + timedelta(seconds=i), net_w))
+        # ⚠️ AND ONE TELEGRAM AT `now` ITSELF. The averager credits a sample's
+        # value over the interval to the NEXT sample, so without this the block
+        # is covered only to the last 5 s mark and 0-5 s of it are extrapolated
+        # from the held value. See the header: at 12 s of remaining that alone
+        # turned a 1500 W fixture into a 613 W one. A real meter does not stop
+        # sending at the last multiple of five either.
+        ctl.p1.submit(sample(now, net_w))
        # ⚠️ ASSIGNED, not read back from `p1.net_w`. This helper stamps
        # `ingest_mono` with an epoch second so the averager (which keys on
        # `ingest_ts`) replays correctly, while `net_w` keys on a MONOTONIC age
@@ -1273,6 +1340,23 @@ _shipped_decide = peakguard.decide

 def _recording_decide(projection, **kw):
    _seen.update(kw)
+    # ⚠️ CI-06. THE PROJECTION OBJECT ITSELF IS KEPT, AND THAT IS WHAT MAKES THE
+    # COMPARISON BELOW A COMPARISON RATHER THAN A RACE. The check under
+    # "THE CONSEQUENCE, ITERATED" says both forms are run "against the same
+    # frozen projection", and until this line existed that sentence was FALSE:
+    # the intent form was decided against a SECOND `PeakTracker.project(
+    # b3.p1.averager, datetime.now())` taken after the cycle had returned, so
+    # the two numbers came from two different instants of the wall clock. The
+    # control law is `excess = 900 x (projected - ceiling) / remaining`, whose
+    # derivative in time is `excess / remaining`, so at a 1500 W floor the two
+    # instants separated at 1500 / remaining W per second and the check's 1.5 W
+    # tolerance bought exactly `remaining / 1000` SECONDS - 900 ms at the top of
+    # a quarter and 6 ms with ten seconds left of it. Measured on this tree, the
+    # gap between the two statements is 13-40 ms idle and larger under load, so
+    # the check was answered by WHERE IN THE QUARTER IT RAN about `gap_ms / 900`
+    # of the time. Keeping the object removes the clock from the comparison
+    # altogether: the tolerance below is EXACT, not widened.
+    _seen["projection"] = projection
    return _shipped_decide(projection, **kw)


@@ -1294,15 +1378,36 @@ check("B3: main.py sizes the floor from the MEASURED battery power, not from "
 # against the same frozen projection - the inverter never follows, so the meter
 # never moves - and the two are allowed to separate over time rather than being
 # judged at a single point where they need not differ.
-_proj3 = PeakTracker.project(b3.p1.averager, datetime.now(timezone.utc))
+#
+# ⚠️ CI-06. "THE SAME FROZEN PROJECTION" IS NOW THE SAME OBJECT. `_proj3` is the
+# `Projection` the real cycle actually graded, captured by `_recording_decide`
+# above, and not a second projection of the same averager taken at a later
+# `datetime.now()`. Every number below therefore comes from ONE instant, and the
+# tolerances that used to absorb the wall clock are gone.
+_proj3 = _seen["projection"]
 _kw = dict(cap_w=CAP_W, reading=b3.peak.peak(), achievable_w=LIVE_MAX_W,
           max_hold_s=b3.p1.averager.max_hold_s, soc=SOC_OK,
           soc_floor=SOC_FLOOR)
 _intent = _shipped_decide(_proj3, batt_w=STANDING, **_kw)
+# The delivered form, re-decided from the SAME projection. It has to reproduce
+# the real controller's own floor EXACTLY or `_kw` is not the call main.py
+# makes - which is a second thing this now grades and did not before, and the
+# one that keeps the identity below honest rather than self-referential.
+_delivered = _shipped_decide(_proj3, batt_w=0.0, **_kw)
+check("the delivered form re-decided from the cycle's OWN projection is the "
+      "number the real Controller wrote, to the bit. The kwargs below are "
+      "main.py's call and not an approximation of it, so the identity that "
+      "follows is a statement about `decide()` and not about this fixture",
+      near(_delivered.floor_w, b3.peak_guard.floor_w))
 check("one cycle of the intent form is exactly the delivered form plus the "
      "command standing on the wire - which is the whole defect in one line: "
-      "watts that were asked for and never arrived, counted as if they had",
-      near(_intent.floor_w - b3.peak_guard.floor_w, STANDING, 1.5))
+      "watts that were asked for and never arrived, counted as if they had. "
+      "⚠️ EXACT, not within 1.5 W: both forms are decided from one Projection "
+      "object, so a tolerance here would only be hiding a clock. CI-06 - the "
+      "1.5 W it used to carry bought `remaining / 1000` seconds and made this "
+      "line answer by where in the quarter the suite happened to run",
+      near(_intent.floor_w - _delivered.floor_w, STANDING)
+      and not _intent.saturated and not _delivered.saturated)

 _i_cmd, _d_batt = STANDING, 0.0
 _i_track, _d_track, _i_sat_at = [], [], None
@@ -5669,6 +5774,86 @@ check("...and so is the last one, which is not a defeat at all but the EDGE OF "
      not MUT[12][1] and EV["min_soc"] <= BMS_FLOOR + 0.05)


+# ==============================================================================
+print()
+print("13. SAFETY-38 round 4: the ORDERED PAIR inside PeakDecision.explain()")
+
+# ⚠️ THE STRING "peak guard idle" APPEARED IN NO test_*.py UNTIL THIS PART.
+# `peakguard.py:493` formats its OWN ATTRIBUTES and RETURNS the sentence:
+#
+#     f"peak guard idle - quarter projects {self.projected_w:.0f} W under a "
+#     f"{self.ceiling_w:.0f} W ceiling ({self.ceiling_from})"
+#
+# Transpose the two and this fixture's row reads "projects 5013 W under a
+# 2300 W ceiling" - a quarter projected 2713 W OVER the ceiling, printed on a
+# row whose own words say the guard is IDLE and whose own flag says ok.
+# MEASURED on this tree: zero-byte edit (50 032 bytes
+# before, 50 032 after, sha256 d95df61a51716c26 -> 2d2ee3d0bcd51251), the
+# emitted sentence changes, and the full 21-file suite stayed GREEN.
+#
+# The sentence was invisible to SAFETY-38's scanner for two rounds because both
+# censuses scored one syntactic sink - APPEND, ASSIGN, LOG ARG - and this one is
+# RETURNED. `tools/symmetric_message_scan.py` census C now scans the return sink
+# and resolves it through the method's call sites; it rediscovered this pair and
+# clamp.py's on its own, which is the only reason to trust the rest of its list.
+#
+# ⚠️ THE OPERANDS COME OFF THE PROJECTION AND OFF `quarter_ceiling_w()`, NOT OFF
+# THE DECISION. `d.projected_w` and `d.ceiling_w` are the very fields the swap
+# exchanges, so grading the sentence against them would compare the swap against
+# itself and pass under it.
+_S38_PROJ = PeakTracker.project(averager_at(CAP_W - 1200.0, 450.0),
+                                B + timedelta(seconds=450))
+_S38_CEIL_W, _S38_CEIL_FROM = quarter_ceiling_w(CAP_W, obs_hi)
+_S38_IDLE = decide(_S38_PROJ, batt_w=0.0, cap_w=CAP_W, reading=obs_hi,
+                   achievable_w=LIVE_MAX_W, max_hold_s=MAX_HOLD_S,
+                   soc=SOC_OK, soc_floor=SOC_FLOOR)
+_S38_LITERAL = (f"quarter projects {_S38_PROJ.projected_w:.0f} W under a "
+                f"{_S38_CEIL_W:.0f} W ceiling")
+_S38_SWAPPED = (f"quarter projects {_S38_CEIL_W:.0f} W under a "
+                f"{_S38_PROJ.projected_w:.0f} W ceiling")
+print(f"    projection {_S38_PROJ.projected_w:.0f} W against a "
+      f"{_S38_CEIL_W:.0f} W ceiling ({_S38_CEIL_FROM})")
+print(f"    {_S38_IDLE.explain()!r}")
+check("PRECONDITION: the guard is IDLE with a projection to print, the ceiling "
+      "came from the MONTH PEAK rather than the cap, and the two operands are "
+      "DIFFERENT NUMBERS that RENDER differently. Equal operands would make the "
+      "transposed sentence identical and every check below decoration",
+      not _S38_IDLE.engaged and _S38_IDLE.projected_w is not None
+      and _S38_CEIL_FROM == CEILING_MONTH_PEAK
+      and _S38_PROJ.projected_w != _S38_CEIL_W
+      and f"{_S38_PROJ.projected_w:.0f}" != f"{_S38_CEIL_W:.0f}"
+      and _S38_PROJ.projected_w < _S38_CEIL_W)
+check("⚠️ THE ORDERED PAIR ON THE CONTIGUOUS LITERAL. The PROJECTION is named "
+      "first and the CEILING second; a substring test for either number passes "
+      "under the transposition because both numbers are still in the sentence, "
+      "so only the ordered pair can tell the two slots apart (MUTATION.md "
+      "habit 14)", _S38_LITERAL in _S38_IDLE.explain())
+check("...and the TRANSPOSED sentence is NOT what it says, so the check above "
+      "discriminates rather than decorates",
+      _S38_SWAPPED not in _S38_IDLE.explain())
+check("...and the row still names WHERE the ceiling came from, which is the "
+      "difference between a cap an operator set and a peak the month already "
+      "banked", f"ceiling ({CEILING_MONTH_PEAK})" in _S38_IDLE.explain())
+
+# THE SHIPPED CONSUMER. `explain()` is not read by anybody until main.py prints
+# it, and round 3's lesson is that the pin belongs on the CALL SITE: the status
+# row at main.py:3313 is what a browser shows, and the action-log line at
+# main.py:1951 is what the release edge writes.
+_c38, _h38 = built(TMP / "s38pin.db")
+_c38.peak_guard = _S38_IDLE
+_rows38 = [r for r in _c38.checks() if "peak guard" in r["text"]]
+print("    status row: " + (_rows38[0]["text"] if _rows38 else "(none)"))
+check("⚠️ ...AND THE SAME ORDERED PAIR ON THE STATUS PAGE (main.py:3313), read "
+      "off the shipped `checks()` rather than off `explain()` a second time. "
+      "This is the surface the owner actually looks at",
+      len(_rows38) == 1 and _S38_LITERAL in _rows38[0]["text"]
+      and _S38_SWAPPED not in _rows38[0]["text"])
+check("...and the row is green and un-warned, which is what makes the "
+      "transposed version dangerous rather than merely untidy: an OK row "
+      "carrying a projection 2713 W OVER its own ceiling is the one an "
+      "operator scrolls past", _rows38[0]["ok"] and not _rows38[0]["warn"]
+      and _S38_CEIL_W - _S38_PROJ.projected_w == 2713.0)
+
 # ==============================================================================
 print()
 shutil.rmtree(TMP, ignore_errors=True)
@@ -1508,6 +1508,50 @@ check("⚠️ AC 1. THE REVERSED UNIT TRIPS AND ITS SIBLING DOES NOT. The eviden
 check("...and the reason names the instrument, so the operator is sent to the "
      "right one", AGAINST_OWN_POWER in _b30.sign_wd.reason)
 print(f"       {_b30.sign_wd.reason!r}")
+# ⚠️ THE LAST CYCLE BEFORE B LATCHED, NAMED RATHER THAN INDEXED - part 5's
+# lesson and 9a's. After the trip B's share is 0 W and its measured power
+# follows it down, so a fixed index reads the REMEDY instead of the evidence.
+# Both operands are read off THIS OBSERVED CYCLE - `last_write` and `batt` off
+# the objects - and not off the fixture's constants, so the check cannot be
+# satisfied by two numbers the fixture happens to hold anyway (habit 2).
+_preb30 = [x for x in _s30 if not x["b"]]
+_midb30 = _preb30[-1]
+print(f"       last cycle before B latched: B stood "
+      f"{_midb30['stood'][1]:+.0f} W, B measured {_midb30['meas'][1]:+.0f} W")
+check("⚠️ ...AND THE ORDERED PAIR, on the ONE SIGN-DISAGREEMENT SENTENCE A "
+      "SHIPPED INSTALL CAN EVER PRINT. Part 9a pins the SITE banner's operand "
+      "order at main.py:1620; that call site is armed only at N>=2 and part 9c "
+      "asserts it is ABSENT at a roster of one, so on the shipped install the "
+      "PER-UNIT banner is the only one there is - and its call site is a "
+      "different line. Swapping the first two arguments at main.py:1560 - "
+      "`evaluate(stood, against, ...)` -> `evaluate(against, stood, ...)` - is "
+      "a ZERO-BYTE edit that changes NO trip decision, because `disagrees()` "
+      "is symmetric in those two arguments (`commanded_w * against_w < 0` with "
+      "an abs() gate on both). Nothing behavioural can see it and the full "
+      "21-file suite stayed green. What it changes is the SENTENCE: 'commanded "
+      "-1000 W against its own measured power +1000 W', the exact opposite of "
+      "which instrument read what, on the line somebody woken by this alarm "
+      "reads first - and it is persisted to `sign_reason` and re-read after a "
+      "restart. Graded on the CONTIGUOUS LITERAL with each value in its own "
+      "slot, per MUTATION.md habit 14: an `in` test on a number grades "
+      "PRESENCE, never ARRANGEMENT",
+      f"commanded {_midb30['stood'][1]:+.0f} W against its own measured power "
+      f"{_midb30['meas'][1]:+.0f} W" in _b30.sign_wd.reason)
+check("PRECONDITION for the line above, and without it that check is "
+      "decoration: the two operands are DIFFERENT NUMBERS and OPPOSITE IN "
+      "SIGN, so transposing them really does produce a different string. A "
+      "cycle where B's share and B's measured power were equal, or where "
+      "either was 0 W, would make the swapped sentence identical to the "
+      "correct one and the assertion could not reach the failure it names",
+      _midb30["stood"][1] != _midb30["meas"][1]
+      and _midb30["stood"][1] * _midb30["meas"][1] < 0
+      and f"{_midb30['stood'][1]:+.0f}" != f"{_midb30['meas'][1]:+.0f}")
+check("...and the SAME ordered pair is what an operator finds AFTER A RESTART, "
+      "because `sign_reason` is the persisted copy of this string. The swap "
+      "survives the container restart the same way the latch does",
+      f"commanded {_midb30['stood'][1]:+.0f} W against its own measured power "
+      f"{_midb30['meas'][1]:+.0f} W"
+      in str(_c30.store.data.get(unit_key("inverter-b", "sign_reason"), "")))
 # ⚠️ READ OFF THE ALLOCATION RECORD, NOT OFF `Controller.reason`. At a roster
 # of two `reason` is the SITE resolution's line - "loop -> 2000 W" - because
 # B's failsafe is a UNIT claim resolved on B's own actuator and never competes
@@ -1764,11 +1808,20 @@ async def _n1_sign():
        return _orig_eval(*a, **kw)

    c.site_sign_wd.evaluate = _spy
-    await _drive(c, n=12, dt=0.2)
-    return c, _n1_calls
+    # ⚠️ THE WATCH READS THE CONTROLLER'S OWN STATE, NOT `_spy`'s ARGUMENTS.
+    # `_n1_calls` records what was HANDED to a detector, so grading the banner
+    # against it would compare the swap against itself - the DEV-02 defect.
+    # `last_write` and `c.grid` are read off the objects the plant moved.
+    seen = await _drive(c, n=12, dt=0.2, watch=lambda c: dict(
+        grid=c.grid,
+        stood=(c.inverters[0].last_write
+               if c.inverters[0].last_write is not None
+               else c.inverters[0].target),
+        tripped=c.inverters[0].sign_wd.tripped))
+    return c, _n1_calls, seen


-_c1s, _n1_site_calls = asyncio.run(_n1_sign())
+_c1s, _n1_site_calls, _seen1s = asyncio.run(_n1_sign())
 _inv1 = _c1s.inverters[0]
 print(f"       roster={_c1s.units}  armed against {_inv1.sign_wd.against!r} "
      f"at {_inv1.sign_wd.cfg.min_w:.0f} W / {_inv1.sign_wd.cfg.hold_s:.0f} s")
@@ -1786,6 +1839,43 @@ check("...the reason sentence still says 'a meter reading', word for word - it "
      "is what an operator reads, what the action log carries and what is "
      "persisted, so it is graded on the literal",
      "against a meter reading" in _inv1.sign_wd.reason)
+# The last cycle before the latch, named rather than indexed: afterwards the
+# failsafe stands 0 W and the plant's meter relaxes, so a fixed index reads the
+# remedy. Both operands come off the controller, not off the fixture's options.
+_pre1s = [x for x in _seen1s if not x["tripped"]]
+_mid1s = _pre1s[-1]
+print(f"       last cycle before the latch: stood {_mid1s['stood']:+.0f} W, "
+      f"meter {_mid1s['grid']:+.0f} W")
+print(f"       {_inv1.sign_wd.reason!r}")
+check("⚠️ ...AND THE ORDERED PAIR ON THE SHIPPING CALL SITE. This is the SAME "
+      "zero-byte defect part 9a closed at main.py:1620, one call site over at "
+      "main.py:1560 - and this is the one a one-inverter install actually "
+      "reaches, since the site detector is never armed here (asserted below). "
+      "`evaluate(stood, against, ...)` -> `evaluate(against, stood, ...)` "
+      "changes no trip decision - `disagrees()` is symmetric in those two "
+      "arguments - and inverts the banner to 'commanded +4000 W against a "
+      "meter reading -2000 W': the loop is standing at -2000 W of charge INTO "
+      "a +4000 W import and the latching banner says the opposite. The "
+      "substring check above passes under the swap, because both numbers are "
+      "still in the sentence; only the ORDERED PAIR can tell the slots apart "
+      "(MUTATION.md habit 14)",
+      f"commanded {_mid1s['stood']:+.0f} W against a meter reading "
+      f"{_mid1s['grid']:+.0f} W" in _inv1.sign_wd.reason)
+check("PRECONDITION: the two operands are DIFFERENT NUMBERS and OPPOSITE IN "
+      "SIGN on that cycle, so a transposition genuinely produces a different "
+      "string. Equal or zero operands would make the swapped banner identical "
+      "and the check above vacuous",
+      _mid1s["stood"] != _mid1s["grid"]
+      and _mid1s["stood"] * _mid1s["grid"] < 0
+      and f"{_mid1s['stood']:+.0f}" != f"{_mid1s['grid']:+.0f}")
+check("...and the persisted copy carries the same ordered pair, under BOTH the "
+      "namespaced key and the flat rollback mirror - which is what an operator "
+      "reads after the restart the latch is designed to survive",
+      f"commanded {_mid1s['stood']:+.0f} W against a meter reading "
+      f"{_mid1s['grid']:+.0f} W" in str(_c1s.store.data.get(REASON_KEY, ""))
+      and f"commanded {_mid1s['stood']:+.0f} W against a meter reading "
+      f"{_mid1s['grid']:+.0f} W"
+      in str(_c1s.store.data.get("sign_reason", "")))
 check("...the latch is under the same namespaced key with the same flat "
      "rollback mirror, and SAFETY-30's site pair is untouched at its default. "
      "A one-inverter install's state file is byte-identical to what it was",
@@ -1993,6 +2083,564 @@ check("...and the counterfactual again: the same site with nothing latched "
      not _bn_n["banner"].startswith("FAILSAFE")
      and _bn_n["banner"] != _bn_b["banner"])

+
+print()
+print("9. SAFETY-38: `site_standing` - the ONE quantity BOTH site guards are")
+print("   asked about - pinned by shares that CANNOT answer for it")
+# ⚠️ WHAT THIS SECTION PINS, AND WHY NOTHING ABOVE IT COULD.
+# `main.py`'s `site_standing = float(sum(standing.values()))` is the first
+# argument of SAFETY-30's site sign detector AND the `commanded_w` handed to
+# SAFETY-18's `looks_frozen()`. It was pinned by NOTHING. THREE mutations of it
+# were demonstrated live against a full green suite, and ALL THREE ARE COVERED
+# HERE:
+#
+#     sum(...) / max(1, len(standing))    the MEAN
+#     max(standing.values(), key=abs)     the LARGEST SHARE
+#     list(standing.values())[0]          the FIRST SHARE
+#
+# ⚠️ ROUND 1 OF THIS CARD SAID THE THIRD ONE WAS ALREADY CLOSED BY SAFETY-32's
+# PACKAGE-WIDE STRUCTURAL PIN AND TOLD FUTURE AUTHORS "DO NOT RE-COVER THAT ONE
+# HERE". THAT WAS FALSE, AND HOW IT BECAME FALSE IS THE USEFUL PART. It was
+# measured ONCE; that single run happened to hit test_peakguard.py's ~20%
+# CI-06 flake, the red was recorded as a mutation KILL, and the claim was then
+# written into four places. RE-MEASURED IN ROUND 2, on release/1.0 @ 86eaef2
+# carrying ONLY the `[0]` edit (+4 bytes, re-read from disk): the full suite is
+# 21/21 GREEN, and test_peakguard.py run FIVE times in isolation on that same
+# mutated tree is PASS PASS PASS PASS PASS. The mutation SURVIVES. (The
+# reviewer's own independent re-measurement of the same tree caught the flake
+# once - PASS PASS PASS FAIL PASS - which is the same verdict: a survivor, plus
+# a demonstration of the flake that produced the original error.) A SINGLE RED
+# FROM test_peakguard.py PROVES NOTHING - re-run it at least five times and NAME
+# the failing check before believing it. That rule is CI-06's, and this card is
+# the third measurement it has corrupted.
+#
+# THE MECHANISM, confirmed by reading 12j's own enumeration rather than by
+# argument. SAFETY-32's part 12j taints names BOUND to roster-carrying values
+# and lists ACCUMULATED in a loop over one. `standing` is neither: it is a dict
+# created empty at main.py:1554 and filled by SUBSCRIPT assignment
+# (`standing[inv.name] = stood`) inside the roster loop, and a subscript store
+# is not a binding 12j follows. So `standing` never enters its taint set at all,
+# and `sum(standing.values())` is not a roster site. Run 12j on a tree carrying
+# the `[0]` mutation and it enumerates main.py:1553, 1555 and 1690 - the three
+# `self.inverters` sites around this code - and NOT 1599. A structural pin
+# cannot see this line. Only the behavioural fixture below can.
+#
+# Identical shape, different meaning - which is precisely the blind spot
+# SAFETY-32 disclosed in its own words ("SEMANTICS. `min` -> `max` -> the mean
+# are edits invisible to any shape pin, permanently"). No shape pin will ever
+# close them. Only a behavioural fixture can, and this is it.
+#
+# ⚠️ WHY PART 5 ABOVE CANNOT SEE THEM, AND IT IS THIS REPOSITORY'S RECURRING
+# DEFECT INSIDE THE SITE HALF OF THE VERY CARD THAT NAMES IT. `_sign_site` is
+# the only N>=2 site fixture in the suite and it runs at
+# `site_sign_disagree_w: 320` with shares of about -2500 W EACH - every one of
+# them individually far OVER the gate. On values like those the sum, the mean
+# and the largest share all clear it, so all three reductions agree, and a
+# check whose two candidate answers happen to be EQUAL cannot observe a change
+# that swaps them. MUTATION.md habit 4. At a roster of ONE it is worse: there
+# `sum == mean == max == the one share` identically, so every mutation is
+# EQUIVALENT there - see 9c, where that identity is asserted rather than
+# assumed.
+#
+# ⚠️ SO THE NUMBERS BELOW ARE CHOSEN TO DISCRIMINATE, AND HERE IS THE
+# ARITHMETIC THEY ARE CHOSEN FOR. Two simulated units rated 220 W and 280 W
+# stand at their own rails, so `standing` is {-220, -280} in roster order:
+#
+#     sum                 -500 W   |500| > 300   OVER the gate   -> TRIPS
+#     mean                -250 W   |250| < 300   under it        -> silent
+#     max(..., key=abs)   -280 W   |280| < 300   under it        -> silent
+#     list(...)[0]        -220 W   |220| < 300   under it        -> silent
+#
+# FOUR DISTINCT MAGNITUDES - 500, 250, 280, 220 - of which exactly ONE clears
+# the SHIPPED 300 W gate. The asymmetry is load-bearing twice over: equal
+# shares would collapse mean, max and first onto one number and the fixture
+# could not tell them apart, and putting the SMALLER unit first is what keeps
+# `[0]` distinct from `max(key=abs)`.
+#
+# ⚠️ THE RATINGS ARE SIMULATED AND ARE NOT ANY REAL INVERTER'S. 220 W and 280 W
+# are chosen for the arithmetic in that table and for nothing else. In
+# particular they are NOT inverter B, which does not physically exist; B's
+# rating is 4600 W FROM ITS DATASHEET (goodwe/NOTES.md 1.1b) and no number in
+# this section is a measurement of anything.
+#
+# ⚠️ THE GATE IS THE SHIPPED ONE AND THE HOLD IS NOT. `site_sign_disagree_w` is
+# left at its default so this fixture is graded against the magnitude an
+# install actually runs; `site_sign_disagree_s` is shortened from 325 s to 2 s
+# because the hold is a wall clock and the campaign behind 325 s is measured on
+# the rig, not here. The gate is the coordinate this section is about.
+from app import peakguard as _pg38                                 # noqa: E402
+from app.freeze import rail_w as _rail_w38                         # noqa: E402
+from app.p1 import P1Sample as _P1Sample38                         # noqa: E402
+import time as _time38                                             # noqa: E402
+
+_S38_A_W, _S38_B_W = 220.0, 280.0     # SIMULATED. See the note above.
+_S38_LOAD_W = 2000.0
+_S38_FROZEN_METER_W = 2500.0
+
+
+def _s38_roster(*ratings):
+    """A CFG-04 `inverters:` roster, which is the shape an N>=2 install runs.
+
+    ⚠️ NOT `_sign_site`'s "build one from the flat keys and append a second".
+    `Controller.__init__` builds `Tuning` FROM the roster - `max_w=site_max_w` -
+    so a unit appended afterwards leaves the site loop bounded at ONE unit's
+    rating. That is harmless where part 3 uses it and fatal here: the whole
+    fixture is a site command standing at the ROSTER's rail.
+    """
+    return [{"name": name, "setpoint_entity": f"number.sp_{tag}",
+             "soc_entity": f"sensor.soc_{tag}", "batt_entity": f"sensor.batt_{tag}",
+             "max_w": w, "bms_soc_floor": 10}
+            for name, tag, w in zip(("inverter-a", "inverter-b", "inverter-c"),
+                                    ("a", "b", "c"), ratings)]
+
+
+class _S38Plant:
+    """Units that obey INSTANTLY and a meter that is `load - sum(measured)`.
+
+    The same modelling choice part 3 makes and for the same reason: an instant
+    plant removes the one mechanism that could make an obedient unit look
+    disobedient, so what remains to be graded is the ATTRIBUTION.
+    """
+
+    def __init__(self, load_w=_S38_LOAD_W):
+        self.load_w = float(load_w)
+        self.writes = []
+        self.calls = []
+        self.ctrl = None
+
+    async def call(self, domain, service, data):
+        self.calls.append((domain, service, data))
+
+    async def limits(self, entity):
+        return None
+
+    def measured(self):
+        if self.ctrl is None:
+            return []
+        return [float((i.last_write if i.last_write is not None else i.target) or 0.0)
+                for i in self.ctrl.inverters]
+
+    async def number(self, entity, invert=False):
+        m = self.measured()
+        if entity == "sensor.grid":
+            return self.load_w - sum(m)
+        for i, tag in enumerate(("a", "b", "c")):
+            if entity == f"sensor.soc_{tag}":
+                return 50.0
+            if entity == f"sensor.batt_{tag}":
+                return m[i] if i < len(m) else None
+        return None
+
+    async def set_number(self, entity, value):
+        self.writes.append((entity, float(value)))
+        return True
+
+
+def _s38_ctrl(hass, ratings, store=None, **over):
+    opts = {"meter_entity": "sensor.grid", "meter_source": "off",
+            "inverters": _s38_roster(*ratings),
+            "gain": -0.6,
+            # The per-unit pair, distinct from the site pair in BOTH
+            # coordinates, for part 3's reason: an equality below must be able
+            # to fail on the magnitude alone or on the hold alone.
+            "unit_sign_disagree_w": 250, "unit_sign_disagree_s": 1,
+            # ⚠️ `site_sign_disagree_w` DELIBERATELY ABSENT - the shipped 300 W
+            # default is the gate this whole section is graded against.
+            "site_sign_disagree_s": 2,
+            # SAFETY-31 is given a long window so the SITE is not stopped by
+            # circulation while this section grades the sign attribution. It is
+            # isolation, not a claim that SAFETY-31 is silent here.
+            "circulation_hold_s": 3600, "auto_start": True}
+    opts.update(over)
+    c = Controller(opts, hass, store if store is not None else _MemStore(),
+                   _P(), stop=asyncio.Event())
+    for inv in c.inverters:
+        inv.dev_min, inv.dev_max = -inv.max_w, inv.max_w
+    c.auto = True
+    hass.ctrl = c
+    return c
+
+
+def _s38_stood(c):
+    return [inv.last_write if inv.last_write is not None else inv.target
+            for inv in c.inverters]
+
+
+print()
+print("9a. the SITE sign detector: per-unit shares EACH BELOW the gate whose")
+print("    SUM clears it - the case the site detector exists for")
+
+
+async def _s38_site():
+    hass = _S38Plant()
+    c = _s38_ctrl(hass, (_S38_A_W, _S38_B_W))
+    seen = []
+    for _ in range(20):
+        await c.read_inputs()
+        await c.cycle()
+        seen.append(dict(grid=c.grid, stood=_s38_stood(c),
+                         meas=[i.batt for i in c.inverters],
+                         site=c.site_sign_wd.tripped,
+                         units=[i.sign_wd.tripped for i in c.inverters],
+                         following=c.following))
+        await asyncio.sleep(0.2)
+    return c, seen
+
+
+_c38, _s38seen = asyncio.run(_s38_site())
+# The last sample BEFORE the trip, named rather than indexed - part 5's lesson.
+# After the trip every command is 0 W, so a fixed index reads the REMEDY.
+_pre38 = [x for x in _s38seen if not x["site"]]
+_mid38 = _pre38[-1]
+_GATE38 = _c38.site_sign_wd.cfg.min_w
+_share38 = list(_mid38["stood"])
+_red38 = {"sum": sum(_share38),
+          "mean": sum(_share38) / max(1, len(_share38)),
+          "max(key=abs)": max(_share38, key=abs),
+          "[0]": _share38[0]}
+print(f"       last cycle before the trip: stood "
+      f"{[round(x) for x in _share38]}  measured "
+      f"{[round(x) for x in _mid38['meas']]}  meter {_mid38['grid']:+.0f} W")
+print(f"       site gate {_GATE38:.0f} W (SHIPPED default), hold "
+      f"{_c38.site_sign_wd.cfg.hold_s:.0f} s")
+for _k, _v in _red38.items():
+    print(f"         {_k:>13} = {_v:+7.1f} W   "
+          f"{'OVER' if abs(_v) > _GATE38 else 'under'} the gate")
+check("PRECONDITION: the gate really is the SHIPPED 300 W, so this fixture is "
+      "graded against the magnitude an install runs and not against a number "
+      "chosen to make it pass",
+      _GATE38 == float(SIGN_OPTION_DEFAULTS["site_sign_disagree_w"]) == 300.0)
+check("⚠️ PRECONDITION, AND IT IS THE WHOLE OF SAFETY-38. EVERY per-unit share "
+      "is BELOW the site gate and their SUM is OVER it. `_sign_site` above "
+      "cannot make this statement - its shares are each individually over the "
+      "gate, so sum, mean and largest-share all agree there and its values "
+      "cannot observe a change that swaps them",
+      len(_share38) >= 2
+      and all(abs(s) < _GATE38 for s in _share38)
+      and abs(sum(_share38)) > _GATE38)
+check("...and the FOUR candidate reductions give FOUR DISTINCT answers on it, "
+      "of which exactly ONE clears the gate. That is what makes this fixture "
+      "able to tell `sum` from the mean, from the largest share and from the "
+      "first share - and it is the property the existing site fixture lacks",
+      len({round(v, 6) for v in _red38.values()}) == 4
+      and [k for k, v in _red38.items() if abs(v) > _GATE38] == ["sum"])
+check("PRECONDITION: EVERY inverter is obeying - each unit's measured power "
+      "agrees in sign with its own share - and the site is charging into an "
+      "importing house. Without this the trip below could be a per-unit fault "
+      "in disguise rather than the site fault this grades",
+      all(s * m > 0 for s, m in zip(_mid38["stood"], _mid38["meas"]))
+      and sum(_mid38["stood"]) * _mid38["grid"] < 0
+      and _mid38["following"] is True)
+check("⚠️ THE SITE WATCHDOG TRIPS ON THE SUM, and no per-unit watchdog does. "
+      "Under ALL THREE semantic mutations - `sum -> mean`, "
+      "`sum -> max(key=abs)` AND `sum -> list(...)[0]` - NOTHING trips, ever: "
+      "the reviewer's tree was still commanding -500 W of charge into a "
+      "+2500 W import at t = 595 s with following=True. This is the check all "
+      "three go red on. `[0]` is here BECAUSE IT IS NOT COVERED ELSEWHERE - "
+      "see the section header for the mis-measurement that said it was",
+      _c38.site_sign_wd.tripped
+      and not any(i.sign_wd.tripped for i in _c38.inverters))
+print(f"       {_c38.site_sign_wd.reason!r}")
+check("⚠️ ...and the sentence an operator reads carries THE SUM IN THE "
+      "COMMANDED SLOT AND THE METER IN THE METER SLOT - the ORDERED PAIR, not "
+      "two numbers loose in a sentence. ROUND 1 ASSERTED `f'{sum(...):.0f} W' "
+      "in reason`, i.e. that '-500 W' appears SOMEWHERE, AND THAT WAS A HOLE "
+      "ONE LINE WIDE. Swapping the detector's first two arguments - "
+      "`evaluate(site_standing, self.grid, ...)` -> "
+      "`evaluate(self.grid, site_standing, ...)`, a ZERO-BYTE edit at "
+      "main.py:1620 - leaves BOTH numbers in the string and moves each into "
+      "the other's slot, so the substring test still passed and the whole "
+      "suite stayed green. The swapped banner reads 'commanded +2500 W "
+      "against a meter reading -500 W': the site is standing at -500 W of "
+      "charge INTO a +2500 W import and the latching, site-stopping banner "
+      "tells the operator the exact opposite, on the one line somebody woken "
+      "by this alarm reads first. watchdog.py:658-665 calls naming the wrong "
+      "instrument there 'a false statement about which instrument produced "
+      "the evidence'. A check whose data cannot reach the failure it names is "
+      "MUTATION.md's own defect; this is the line that closes it",
+      f"commanded {sum(_share38):+.0f} W against a meter reading "
+      f"{_mid38['grid']:+.0f} W" in _c38.site_sign_wd.reason)
+check("...and it stops the WHOLE site, through the `sign_site` claim by name "
+      "rather than by some other guard happening to stop it",
+      _c38.target == 0.0 and "sign_site" in _c38.reason
+      and all(i.target == 0.0 for i in _c38.inverters)
+      and _c38.store.data.get("site_sign_tripped") is True)
+# ⚠️ THE COUNTERFACTUAL, and it is what says the check above is produced by the
+# SUM crossing the gate rather than by two inverters being present. Same plant,
+# same roster shape, same everything - except the units are rated so that the
+# sum lands UNDER the gate. Nothing may trip.
+_S38_SMALL = (120.0, 130.0)          # sum 250 W: under the 300 W gate
+
+
+async def _s38_under():
+    hass = _S38Plant()
+    c = _s38_ctrl(hass, _S38_SMALL)
+    for _ in range(20):
+        await c.read_inputs()
+        await c.cycle()
+        await asyncio.sleep(0.2)
+    return c
+
+
+_c38u = asyncio.run(_s38_under())
+print(f"       counterfactual: stood {[round(x) for x in _s38_stood(_c38u)]}  "
+      f"sum {sum(_s38_stood(_c38u)):+.0f} W  meter {_c38u.grid:+.0f} W")
+check("...and the counterfactual: the SAME inverted-gain site whose shares sum "
+      "to 250 W - under the gate - does NOT trip, over the same 20 cycles. So "
+      "the trip above is the sum crossing 300 W and not the mere presence of a "
+      "second inverter",
+      abs(sum(_s38_stood(_c38u))) < _GATE38
+      and not _c38u.site_sign_wd.tripped
+      and not any(i.sign_wd.tripped for i in _c38u.inverters))
+# ⚠️ AND A SECOND COUNTERFACTUAL, WHICH EXISTS BECAUSE OF A MUTATION THE CHECKS
+# ABOVE COULD NOT SEE AND THIS SEARCH WENT LOOKING FOR.
+# `site_standing = float(self.target)` - the arbiter's SITE TARGET instead of
+# the sum of what actually stands on the wire - is -11 bytes, and it survived
+# every check above AND the whole 20-file suite, because in every fixture so
+# far the two are the same number. THEY ARE NOT THE SAME NUMBER when a setpoint
+# device's own reported range is narrower than its `max_w`: the `device`
+# P_SAFETY claim is filed PER ACTUATOR (main.py, `actuator_of("device", inv)`),
+# so it bounds each unit's SHARE and never the site target, and
+# `clamp_to_rating()` clips again on the way out. Here the site asks for -500 W
+# and -250 W stands.
+#
+# WHICH ONE THE GUARDS MEAN IS ALREADY WRITTEN DOWN, IN BOTH OF THEM: SAFETY-02
+# grades "the command standing on the wire", and `looks_frozen()`'s docstring
+# says `commanded_w` is "the EMITTED setpoint - what the arbiter resolved and
+# `write_setpoint()` put on the wire - not the loop's raw wish". SAFETY-20 is
+# the whole card about the difference. This check is those sentences made to
+# bite: on the site target the detector fires on a site that is standing at
+# -250 W against a +2250 W meter - under its own 300 W gate - which is a
+# LATCHING, site-stopping false trip on an install whose inverters simply
+# report a narrower range than the operator typed.
+_S38_DEV = (120.0, 130.0)          # narrower than the 220/280 W ratings
+
+
+async def _s38_devclamped():
+    hass = _S38Plant()
+    c = _s38_ctrl(hass, (_S38_A_W, _S38_B_W))
+    for inv, d in zip(c.inverters, _S38_DEV):
+        inv.dev_min, inv.dev_max = -d, d
+    for _ in range(20):
+        await c.read_inputs()
+        await c.cycle()
+        await asyncio.sleep(0.2)
+    return c
+
+
+_c38d = asyncio.run(_s38_devclamped())
+_stood38d = _s38_stood(_c38d)
+print(f"       device-clamped: site target {_c38d.target:+.0f} W but only "
+      f"{[round(x) for x in _stood38d]} = {sum(_stood38d):+.0f} W stands, "
+      f"meter {_c38d.grid:+.0f} W")
+check("PRECONDITION: the site TARGET and the EMITTED total are DIFFERENT "
+      "numbers here, on opposite sides of the gate - -500 W asked, -250 W "
+      "standing. Without that separation this check and the one above compare "
+      "two values that happen to be equal, which is the defect this card is "
+      "the sixth instance of",
+      abs(_c38d.target) > _GATE38 and abs(sum(_stood38d)) < _GATE38)
+check("⚠️ ...and NOTHING TRIPS, because the quantity graded is what STANDS ON "
+      "THE WIRE and not what the arbiter asked for. `float(self.target)` is "
+      "-11 bytes, survives the other 20 files, and turns this ordinary "
+      "narrow-rating install into a latching site-wide false trip",
+      not _c38d.site_sign_wd.tripped
+      and not any(i.sign_wd.tripped for i in _c38d.inverters)
+      and _c38d.target != 0.0)
+
+
+print()
+print("9b. THE SECOND CONSUMER: the same value is SAFETY-18's `commanded_w`")
+print("    inside `looks_frozen()`, and both mutations blind it too")
+# ⚠️ THIS IS THE AC THE CARD REFUSES TO LET BE SCOPED OUT SILENTLY.
+# `site_standing` is handed to `looks_frozen()` at main.py's `peakguard.decide(
+# ..., frozen=...)` call, where it is the EMITTED command graded against the
+# site rail. Both surviving mutations shrink it there too, and nothing went red.
+#
+# THE RAIL ARITHMETIC, and it is the same discrimination as 9a at a different
+# threshold: the site rail is `RAIL_FRAC * site_max_w` = 0.95 * 500 = 475 W.
+#
+#     sum                 500 W   >= 475   RAILED  -> BLIND_FROZEN, floor 0 W
+#     mean                250 W   <  475   silent
+#     max(..., key=abs)   280 W   <  475   silent
+#     list(...)[0]        220 W   <  475   silent
+#
+# ⚠️ THE SIGN IS FLIPPED FROM 9a ON PURPOSE. Here the gain is the SHIPPED
+# POSITIVE one and the frozen meter reads IMPORT, so the site discharges +500 W
+# against a +2500 W import - the two agree in sign, SAFETY-30 has nothing to
+# say, and this section grades SAFETY-18 alone. Reusing 9a's inverted gain
+# would have the site sign latch park everything at 0 W and the freeze
+# conjunction could then never be true: a check measuring the other guard's
+# remedy.
+#
+# WHAT THE MUTATIONS COST HERE, measured rather than asserted: on the shipped
+# tree the guard goes blind and files `floor_w = 0.0` - "the battery may not
+# import while the billed quarter cannot be measured". Under both mutations it
+# is NOT BLIND AT ALL and files `floor_w = None`, so the site may go on
+# charging through a quarter whose billed average is unobservable. That is the
+# capacity-tariff hazard SAFETY-18 exists for, silently disarmed.
+
+
+class _S38Src:
+    """The transport's own `unchanged_s`, which only homewizard_local has."""
+
+    def __init__(self, unchanged_s):
+        self.unchanged_s = float(unchanged_s)
+
+
+def _s38_feed(c, w, ts=None, mono=None):
+    now = ts if ts is not None else datetime.now(timezone.utc)
+    c.p1.submit(_P1Sample38(
+        ingest_ts=now,
+        ingest_mono=mono if mono is not None else _time38.monotonic(),
+        telegram_ts=now, source="homewizard_local",
+        import_w=max(w, 0.0), export_w=max(-w, 0.0), net_w=w,
+        per_phase_w=(w,), per_phase_import_w=(max(w, 0.0),)))
+
+
+def _s38_seed_quarter(c, w):
+    """Backfill the OPEN quarter with the same stuck value, at 10 s spacing.
+
+    ⚠️ THIS IS NOT DECORATION. Without it the open block is mostly uncovered and
+    `blindness()` answers BLIND_COVERAGE - which is still blind, still floor
+    0 W, and would therefore MASK the mutations: the mutant would reach the
+    same action by a different route and a check on the action alone could not
+    see the difference it names. Seeded, the mutant is not blind at ALL, which
+    is the honest measurement of what the mutation costs. A meter that has been
+    stuck at the same reading all quarter is also what SAFETY-18 is about.
+    """
+    wall = _time38.time()
+    q0 = (int(wall) // 900) * 900
+    mono0 = _time38.monotonic() - (wall - q0)
+    t = float(q0)
+    while t < wall:
+        _s38_feed(c, w, datetime.fromtimestamp(t, timezone.utc), mono0 + (t - q0))
+        t += 10.0
+
+
+def _s38_frozen_ctrl(hass, ratings, unchanged_s=600.0, gain=0.05):
+    # ⚠️ `gain` 0.05 IS THE SCHEMA FLOOR AND IT IS HERE TO BUY A RAMP. At the
+    # shipped 0.6 the loop is at the rail on cycle 0 and the fixture has no
+    # BELOW-the-rail cycles to use as its counterfactual. At 0.05 the site
+    # climbs 125 W a cycle and crosses 475 W part way through the run, so the
+    # SAME run carries both answers.
+    c = _s38_ctrl(hass, ratings, meter_source="homewizard_local",
+                  p1_host="meter.local", gain=gain)
+    c.p1_source = _S38Src(unchanged_s)
+    return c
+
+
+async def _s38_frozen(ratings, meter_w=_S38_FROZEN_METER_W, n=8):
+    hass = _S38Plant()
+    c = _s38_frozen_ctrl(hass, ratings)
+    _s38_seed_quarter(c, meter_w)
+    seen = []
+    for _ in range(n):
+        _s38_feed(c, meter_w)
+        await c.read_inputs()
+        await c.cycle()
+        pg = c.peak_guard
+        seen.append(dict(stood=_s38_stood(c),
+                         blind=None if pg is None else pg.blind,
+                         floor=None if pg is None else pg.floor_w))
+        await asyncio.sleep(0.05)
+    return c, seen
+
+
+_c38f, _s38f = asyncio.run(_s38_frozen((_S38_A_W, _S38_B_W)))
+_RAIL38 = _rail_w38(_c38f.site_max_w,
+                    dev_min=_c38f.site_dev_bound("dev_min"),
+                    dev_max=_c38f.site_dev_bound("dev_max"))
+_last38 = _s38f[-1]
+_below38 = [x for x in _s38f if abs(sum(x["stood"])) < _RAIL38]
+print(f"       site rail {_RAIL38:.0f} W of site_max_w {_c38f.site_max_w:.0f} W; "
+      f"meter stuck at {_S38_FROZEN_METER_W:+.0f} W for "
+      f"{_c38f.p1_source.unchanged_s:.0f} s (freeze hold "
+      f"{_c38f.freeze_wd.cfg.hold_s:.0f} s)")
+for _x in _s38f:
+    print("         stood %-16s sum %+7.1f W   floor=%s   blind=%r"
+          % ([round(v) for v in _x["stood"]], sum(_x["stood"]),
+             _x["floor"], _x["blind"]))
+check("PRECONDITION: at the rail EVERY per-unit share is BELOW the site rail "
+      "and their SUM is at or over it - the same discrimination as 9a, at "
+      "SAFETY-18's threshold instead of SAFETY-30's. `[0]`, the mean and the "
+      "largest share are 220, 250 and 280 W against a 475 W rail",
+      len(_last38["stood"]) >= 2
+      and all(abs(s) < _RAIL38 for s in _last38["stood"])
+      and abs(sum(_last38["stood"])) >= _RAIL38
+      and len({round(v, 6) for v in
+               (sum(_last38["stood"]),
+                sum(_last38["stood"]) / len(_last38["stood"]),
+                max(_last38["stood"], key=abs),
+                _last38["stood"][0])}) == 4)
+check("⚠️ THE PEAK GUARD GOES BLIND ON SAFETY-18's CONJUNCTION and forbids "
+      "charging - floor 0 W - because the SITE's total command is at the rail "
+      "while the meter has stopped moving. Under `sum -> mean` and "
+      "`sum -> max(key=abs)` it is not blind at all and files no floor, so the "
+      "battery may keep importing through an unmeasurable billed quarter. This "
+      "is the second consumer, and it is covered rather than scoped out",
+      _last38["blind"] == _pg38.BLIND_FROZEN and _last38["floor"] == 0.0)
+check("...and the counterfactual, from the SAME run: on the earlier cycles the "
+      "site command had not yet reached the rail, and the guard did NOT report "
+      "SAFETY-18 - with the meter equally frozen the whole time. So the "
+      "verdict is produced by the COMMAND MAGNITUDE `site_standing` carries, "
+      "not by `unchanged_s` alone",
+      len(_below38) >= 2
+      and all(x["blind"] != _pg38.BLIND_FROZEN for x in _below38))
+
+
+print()
+print("9c. AT ONE INVERTER NOTHING CHANGES, and 'nothing' is asserted")
+# ⚠️ THE REASON THIS SUBSECTION EXISTS. At a roster of one `standing` has a
+# single entry, so `sum`, the mean, `max(key=abs)` and `[0]` are THE SAME
+# NUMBER: all three mutations are genuinely EQUIVALENT there and no fixture at
+# N=1 can ever separate them. That is a fact about the arithmetic, and leaving
+# it implicit is how "the shipped install is covered" gets believed. It is
+# asserted here, on a real one-inverter controller's own standing command, so
+# the claim rests on the roster rather than on the reader.
+_S38_ONE = (500.0,)
+
+
+async def _s38_one():
+    hass = _S38Plant()
+    c = _s38_frozen_ctrl(hass, _S38_ONE)
+    _s38_seed_quarter(c, _S38_FROZEN_METER_W)
+    for _ in range(8):
+        _s38_feed(c, _S38_FROZEN_METER_W)
+        await c.read_inputs()
+        await c.cycle()
+        await asyncio.sleep(0.05)
+    return c
+
+
+_c38one = asyncio.run(_s38_one())
+_one38 = _s38_stood(_c38one)
+_onered38 = (sum(_one38), sum(_one38) / max(1, len(_one38)),
+             max(_one38, key=abs), _one38[0])
+print(f"       roster of {len(_c38one.inverters)}: stood "
+      f"{[round(v) for v in _one38]}  -> sum/mean/max/first = "
+      f"{tuple(round(v, 1) for v in _onered38)}")
+check("at a roster of ONE the four reductions are ONE NUMBER - so all three "
+      "mutations of `site_standing` are EQUIVALENT on a shipped install and no "
+      "N=1 fixture could ever tell them apart. That is why this card needed a "
+      "roster of two, stated as an assertion rather than left to the reader",
+      len(_c38one.inverters) == 1
+      and len({round(v, 6) for v in _onered38}) == 1)
+check("...and the one-inverter site still reaches SAFETY-18's verdict on that "
+      "same number, unchanged: the command is at the rail, the meter has "
+      "stopped moving, the guard is blind and forbids charging",
+      _c38one.peak_guard is not None
+      and _c38one.peak_guard.blind == _pg38.BLIND_FROZEN
+      and _c38one.peak_guard.floor_w == 0.0
+      and abs(sum(_one38)) >= _rail_w38(
+          _c38one.site_max_w,
+          dev_min=_c38one.site_dev_bound("dev_min"),
+          dev_max=_c38one.site_dev_bound("dev_max")))
+check("...and the SITE sign detector is still absent at a roster of one - part "
+      "7 counts the calls; this only records that a fixture built the other "
+      "way round, from an `inverters:` roster, reaches the same state",
+      not _c38one.site_sign_wd.tripped
+      and _c38one.site_sign_wd.disagree_since is None)
+
 print()
 if fails:
    print(f"{len(fails)} FAILED: {', '.join(fails)}")
@@ -0,0 +1,878 @@
+#!/usr/bin/env python3
+"""SAFETY-38 round 3 - the SYMMETRIC-PREDICATE FAMILY, enumerated by machine.
+
+WHAT IT LOOKS FOR, in one sentence: a call whose argument ORDER is load-bearing
+for a MESSAGE and for nothing else - so swapping the arguments cannot change a
+single decision, is invisible to every behavioural check BY CONSTRUCTION, and
+still inverts what an operator reads on the line they are woken by.
+
+⚠️ WHY IT IS AN INSTRUMENT AND NOT A LIST. MUTATION.md habit 12: "a hand-written
+scope is the same defect as a hand-written fixture". SAFETY-38 met this family
+twice - `SignWatchdog.evaluate()` called at `main.py:1620` (round 2) and at
+`main.py:1560` (round 3), ONE CALL SITE OVER - and both times the enumeration
+was written by hand and both times it was short. So the scope is computed.
+
+------------------------------------------------------------------------------
+THE TEST IT APPLIES
+
+For every function in `app/` and every pair (a, b) of its parameters:
+
+    rename a -> b and b -> a throughout the body, ERASE every string literal
+    and f-string, CANONICALISE the commutative operators, and compare the two
+    ASTs. If they are EQUAL, nothing the function DECIDES can depend on which
+    of the two values arrived first.
+
+Then, if some f-string in that function mentions BOTH names, the order is
+load-bearing for the MESSAGE ALONE, and the pair is reported.
+
+⚠️ THE SYMMETRY IS USUALLY ONE CALL DEEP, WHICH IS WHY THIS IS A FIXPOINT AND
+NOT A SINGLE PASS. `SignWatchdog.evaluate()` does not compare its two arguments
+itself; it hands them to `watchdog.disagrees()`, whose body is
+`commanded_w * against_w < 0 and abs(commanded_w) > min_w and
+abs(against_w) > min_w`. An intraprocedural scan sees `disagrees(a, b, ...)`
+become `disagrees(b, a, ...)`, calls that a difference, and reports NOTHING -
+which is exactly what the first version of this file did, on a tree where the
+answer was already known. So symmetric pairs discovered in one round are used
+to canonicalise CALL ARGUMENTS in the next, and the scan iterates until the set
+stops growing.
+
+CANONICALISATION, and each entry is here because something in `app/` needs it:
+  * `a * b`, `a + b`               - operand order sorted (`disagrees`)
+  * `x and y`, `x or y`            - term order sorted (`disagrees`' conjunction)
+  * `a == b`, `a != b`             - operand order sorted
+  * `min(a, b)`, `max(a, b)`       - argument order sorted (`clamp_to_rating`)
+  * a tuple/list/set LITERAL being iterated - element order sorted
+    (`rail_ceiling_w`'s `for bound in (dev_min, dev_max)`)
+  * arguments at a KNOWN SYMMETRIC POSITION PAIR of a called function - sorted
+    (the fixpoint)
+
+Equal ASTs after the rename is a SUFFICIENT condition for behavioural
+invariance, not a necessary one. This scan therefore UNDER-REPORTS and says so
+- see "WHAT THIS CANNOT SEE". That is the conservative direction: everything it
+names is genuinely in the family, and the gap is stated with its shape.
+
+Run: `python3 tools/symmetric_message_scan.py [--quiet]` from goodwe_controller/.
+Exit status is 0 always; it is a census, not a gate.
+"""
+from __future__ import annotations
+
+import ast
+import itertools
+import pathlib
+import sys
+
+APP = pathlib.Path(__file__).resolve().parent.parent / "app"
+
+# {function name: {(i, j) positional index pairs that are interchangeable}}
+_SYM: dict[str, set[tuple[int, int]]] = {}
+# ⚠️ AND THE SAME THING FOR KEYWORD-ONLY PARAMETERS, WHICH THE FIRST FIXPOINT
+# DROPPED. `freeze.rail_ceiling_w(max_w, *, dev_min=None, dev_max=None)` folds
+# its two device bounds with `for bound in (dev_min, dev_max): ceiling = min(
+# ceiling, abs(bound))` - perfectly symmetric - and `rail_unreachable()` prints
+# `"a range of {dev_min}...{dev_max} W"`. A scan that only followed POSITIONAL
+# arguments called that pair asymmetric and hid a genuine member of the family
+# behind an implementation detail of its own traversal.
+_SYM_KW: dict[str, set[tuple[str, str]]] = {}
+
+
+class _Canon(ast.NodeTransformer):
+    """Rename one pair, erase every string, and sort what commutes."""
+
+    COMMUTATIVE_BINOP = (ast.Mult, ast.Add, ast.BitAnd, ast.BitOr, ast.BitXor)
+    COMMUTATIVE_CMP = (ast.Eq, ast.NotEq)
+    COMMUTATIVE_CALL = ("min", "max")
+
+    def __init__(self, a: str = "", b: str = ""):
+        self.a, self.b = a, b
+
+    # -- the rename ---------------------------------------------------------
+    def visit_Name(self, node):
+        self.generic_visit(node)
+        if self.a and node.id == self.a:
+            node.id = self.b
+        elif self.b and node.id == self.b:
+            node.id = self.a
+        return node
+
+    def visit_arg(self, node):
+        if self.a and node.arg == self.a:
+            node.arg = self.b
+        elif self.b and node.arg == self.b:
+            node.arg = self.a
+        return node
+
+    # -- the message is exactly what is ALLOWED to differ --------------------
+    def visit_JoinedStr(self, node):
+        return ast.Constant(value="<msg>")
+
+    def visit_Constant(self, node):
+        if isinstance(node.value, str):
+            return ast.Constant(value="<msg>")
+        return node
+
+    # -- canonicalisation ---------------------------------------------------
+    def visit_BinOp(self, node):
+        self.generic_visit(node)
+        if isinstance(node.op, self.COMMUTATIVE_BINOP):
+            l, r = ast.dump(node.left), ast.dump(node.right)
+            if l > r:
+                node.left, node.right = node.right, node.left
+        return node
+
+    def visit_BoolOp(self, node):
+        self.generic_visit(node)
+        node.values = sorted(node.values, key=ast.dump)
+        return node
+
+    def visit_Compare(self, node):
+        self.generic_visit(node)
+        if (len(node.ops) == 1
+                and isinstance(node.ops[0], self.COMMUTATIVE_CMP)):
+            l, r = ast.dump(node.left), ast.dump(node.comparators[0])
+            if l > r:
+                node.left, node.comparators[0] = node.comparators[0], node.left
+        return node
+
+    def visit_For(self, node):
+        self.generic_visit(node)
+        if isinstance(node.iter, (ast.Tuple, ast.List, ast.Set)):
+            node.iter.elts = sorted(node.iter.elts, key=ast.dump)
+        return node
+
+    def visit_Call(self, node):
+        self.generic_visit(node)
+        name = (node.func.id if isinstance(node.func, ast.Name)
+                else node.func.attr if isinstance(node.func, ast.Attribute)
+                else "")
+        if name in self.COMMUTATIVE_CALL and len(node.args) == 2 \
+                and not node.keywords:
+            if ast.dump(node.args[0]) > ast.dump(node.args[1]):
+                node.args = [node.args[1], node.args[0]]
+            return node
+        # the fixpoint: sort the arguments at a known symmetric position pair
+        for (i, j) in sorted(_SYM.get(name, ())):
+            if j < len(node.args):
+                if ast.dump(node.args[i]) > ast.dump(node.args[j]):
+                    node.args[i], node.args[j] = node.args[j], node.args[i]
+        # ...and at a known symmetric KEYWORD pair
+        for (ka, kb) in sorted(_SYM_KW.get(name, ())):
+            ia = next((k for k, w in enumerate(node.keywords)
+                       if w.arg == ka), None)
+            ib = next((k for k, w in enumerate(node.keywords)
+                       if w.arg == kb), None)
+            if ia is not None and ib is not None:
+                va, vb = node.keywords[ia].value, node.keywords[ib].value
+                if ast.dump(va) > ast.dump(vb):
+                    node.keywords[ia].value, node.keywords[ib].value = vb, va
+        return node
+
+
+def _canon(src: str, a: str = "", b: str = "") -> str:
+    return ast.dump(_Canon(a, b).visit(ast.parse(src)))
+
+
+# ⚠️ THE SINK IS HALF THE CLAIM, AND THE FIRST VERSION OF THIS SCAN OMITTED IT.
+# Erasing every f-string makes a function whose ONLY job is to FORMAT one look
+# perfectly symmetric - `store.unit_key(unit, key)` and
+# `mqtt.unit_state_key(slug, key)` both came back as "the swap changes nothing"
+# when in fact the string IS the return value: swapping there renames a STORE
+# KEY and an MQTT TOPIC, which is a behaviour change every ordinary check can
+# see, and MAINT-05 is the card about exactly that. The family this file is
+# looking for is narrower - the string goes to an OPERATOR and to nobody else -
+# so each sentence is classified by where it GOES.
+_LOG_SINKS = {"debug", "info", "warning", "warn", "error", "exception",
+              "critical", "log", "log_event", "notify", "persistent_notify"}
+_MSG_ATTRS = {"reason", "message", "msg", "banner", "detail", "note",
+              "explanation", "why", "text"}
+
+
+def _sink_of(fn, target, follow=True):
+    """RETURN | MESSAGE | OTHER - where this f-string node ends up.
+
+    `follow` is the ONE step of data flow below, and it is off on the recursive
+    call so that two locals that interpolate each other cannot loop forever.
+    """
+    for stmt in ast.walk(fn):
+        for child in ast.iter_child_nodes(stmt):
+            pass
+    # a parent map is cheaper than repeated walks
+    parent = {}
+    for node in ast.walk(fn):
+        for child in ast.iter_child_nodes(node):
+            parent[id(child)] = node
+    cur = target
+    while id(cur) in parent:
+        up = parent[id(cur)]
+        if isinstance(up, ast.Return):
+            return "RETURN"
+        if isinstance(up, ast.Raise):
+            return "MESSAGE"
+        if isinstance(up, (ast.Assign, ast.AnnAssign, ast.AugAssign)):
+            tgts = (up.targets if isinstance(up, ast.Assign) else [up.target])
+            for t in tgts:
+                if isinstance(t, ast.Attribute) and t.attr in _MSG_ATTRS:
+                    return "MESSAGE"
+                if isinstance(t, ast.Name) and t.id in _MSG_ATTRS:
+                    return "MESSAGE"
+            # ⚠️ ONE STEP OF DATA FLOW, AND IT IS NOT OPTIONAL. `main.py`'s
+            # status page builds the device-range clause into a LOCAL - `_cap =
+            # "; ".join(f"... accepts only {inv.dev_min}...{inv.dev_max} W" ...)`
+            # - and only then concatenates it into the row's `text`. Stopping at
+            # the assignment scores that OTHER and drops a member this card
+            # MEASURED as a live survivor (0 bytes, 21/21 green). So: if the
+            # name assigned here is interpolated into some other sentence in the
+            # same function that IS a message, this one is a message too.
+            if follow:
+                for t in tgts:
+                    if isinstance(t, ast.Name) and _feeds_a_message(fn, t.id,
+                                                                    up):
+                        return "MESSAGE"
+            return "OTHER"
+        # ⚠️ ROUND 4. A SENTENCE HANDED TO A CONSTRUCTOR AS `reason=` IS A
+        # MESSAGE, and scoring only ASSIGNMENTS missed every one of them. This
+        # codebase builds most of its operator sentences that way -
+        # `ArbitrageDecision(action=..., reason=f"...")`,
+        # `out.append({"text": f"..."})` - so the sentence never touches a name
+        # this walker was watching. arbitrage.py's two DISCHARGE/CHARGE reasons
+        # were scored OTHER for exactly this and are genuine members.
+        if isinstance(up, ast.keyword) and up.arg in _MSG_ATTRS:
+            return "MESSAGE"
+        if isinstance(up, ast.Dict):
+            for k, v in zip(up.keys, up.values):
+                if (v is cur and isinstance(k, ast.Constant)
+                        and k.value in _MSG_ATTRS):
+                    return "MESSAGE"
+        if isinstance(up, ast.Call):
+            name = (up.func.attr if isinstance(up.func, ast.Attribute)
+                    else up.func.id if isinstance(up.func, ast.Name) else "")
+            if name in _LOG_SINKS:
+                return "MESSAGE"
+            if name == "append":
+                return "MESSAGE"
+        cur = up
+    return "OTHER"
+
+
+def _feeds_a_message(fn, name, origin):
+    """Is `name` interpolated into some OTHER sentence that IS a message?"""
+    for node in ast.walk(fn):
+        if not isinstance(node, ast.JoinedStr) or node is origin:
+            continue
+        used = any(isinstance(x, ast.Name) and x.id == name
+                   for v in node.values if isinstance(v, ast.FormattedValue)
+                   for x in ast.walk(v.value))
+        if used and _sink_of(fn, node, follow=False) == "MESSAGE":
+            return True
+    return False
+
+
+def _fstring_pairs(fn, params):
+    """{(a, b): [(lineno, sink), ...]} for every f-string mentioning both."""
+    out: dict[tuple[str, str], list[tuple[int, str]]] = {}
+    for node in ast.walk(fn):
+        if not isinstance(node, ast.JoinedStr):
+            continue
+        used = set()
+        for v in node.values:
+            if isinstance(v, ast.FormattedValue):
+                for x in ast.walk(v.value):
+                    if isinstance(x, ast.Name) and x.id in params:
+                        used.add(x.id)
+        if len(used) < 2:
+            continue
+        sink = _sink_of(fn, node)
+        for a, b in itertools.combinations(sorted(used), 2):
+            out.setdefault((a, b), []).append((node.lineno, sink))
+    return out
+
+
+def _functions():
+    for path in sorted(APP.glob("*.py")):
+        tree = ast.parse(path.read_text())
+        for fn in ast.walk(tree):
+            if isinstance(fn, (ast.FunctionDef, ast.AsyncFunctionDef)):
+                yield path, fn
+
+
+def _positional(fn):
+    return [a.arg for a in fn.args.posonlyargs + fn.args.args
+            if a.arg != "self"]
+
+
+def _all_params(fn):
+    return _positional(fn) + [a.arg for a in fn.args.kwonlyargs]
+
+
+def _body_src(fn) -> str:
+    """The function's BODY alone.
+
+    ⚠️ NOT `ast.unparse(fn)`. The signature lists the parameters IN ORDER, so
+    renaming a pair inside it reorders `arguments.args` and every function in
+    the repository compares unequal to itself - which is what the first version
+    of this scan did, silently, and it reported an empty family on a tree whose
+    answer was already known. The claim being tested is about what the body
+    DECIDES, and the body is what is compared.
+    """
+    return ast.unparse(ast.Module(body=list(fn.body), type_ignores=[]))
+
+
+def _symmetric(fn, a, b) -> bool:
+    src = _body_src(fn)
+    return _canon(src) == _canon(src, a, b)
+
+
+def build_fixpoint(max_rounds=6):
+    """Fill `_SYM` until it stops growing. Returns the number of rounds."""
+    for round_no in range(1, max_rounds + 1):
+        grew = False
+        for _path, fn in _functions():
+            pos = _positional(fn)
+            kws = [a.arg for a in fn.args.kwonlyargs]
+            if len(pos) + len(kws) < 2:
+                continue
+            found = set()
+            for i, j in itertools.combinations(range(len(pos)), 2):
+                if _symmetric(fn, pos[i], pos[j]):
+                    found.add((i, j))
+            found_kw = set()
+            for ka, kb in itertools.combinations(sorted(kws), 2):
+                if _symmetric(fn, ka, kb):
+                    found_kw.add((ka, kb))
+            if found - _SYM.get(fn.name, set()):
+                _SYM.setdefault(fn.name, set()).update(found)
+                grew = True
+            if found_kw - _SYM_KW.get(fn.name, set()):
+                _SYM_KW.setdefault(fn.name, set()).update(found_kw)
+                grew = True
+        if not grew:
+            return round_no
+    return max_rounds
+
+
+def scan():
+    rows = []
+    for path, fn in _functions():
+        params = _all_params(fn)
+        if len(params) < 2:
+            continue
+        kwonly = {a.arg for a in fn.args.kwonlyargs}
+        for (a, b), hits in sorted(_fstring_pairs(fn, params).items()):
+            rows.append(dict(
+                module=path.name, func=fn.name, line=fn.lineno, a=a, b=b,
+                msg_lines=sorted(set(hits)),
+                sinks={s for _l, s in hits},
+                symmetric=_symmetric(fn, a, b),
+                positional=not (a in kwonly or b in kwonly)))
+    return rows
+
+
+# =============================================================================
+# CENSUS B - THE SENTENCE THE CALLER BUILDS
+# =============================================================================
+# ⚠️ CENSUS A ABOVE ONLY SEES A CALLEE FORMATTING ITS OWN PARAMETERS, AND THAT
+# WAS GAP 2 OF ITS OWN "WHAT THIS CANNOT SEE" LIST. The other half of the family
+# never passes through a function boundary at all: an operator sentence built
+# where it is printed, interpolating two values that are INTERCHANGEABLE BY
+# SHAPE. `main.py`'s status page says
+#
+#     f"{inv.setpoint_entity or inv.name} accepts only {inv.dev_min}...{inv.dev_max} W"
+#
+# and transposing those two costs ZERO BYTES, changes nothing any check can
+# observe, and tells the operator a range backwards. No predicate is involved,
+# so census A's symmetry test has nothing to test.
+#
+# THE TEST: inside one MESSAGE-sink f-string, take every pair of interpolated
+# expressions, blank every attribute NAME and every string CONSTANT, and compare.
+# If the blanked forms are EQUAL while the originals DIFFER, the two expressions
+# are the same shape with one leaf changed - `inv.dev_min` / `inv.dev_max`,
+# `site_dev_bound("dev_min")` / `site_dev_bound("dev_max")` - which is exactly
+# the pair a transposition swaps. Same direction as census A: it under-reports
+# (two values of the same KIND spelled differently are missed) rather than
+# inventing members.
+
+
+
+class _Blank(ast.NodeTransformer):
+    def visit_Attribute(self, node):
+        self.generic_visit(node)
+        node.attr = "<leaf>"
+        return node
+
+    def visit_Constant(self, node):
+        if isinstance(node.value, str):
+            return ast.Constant(value="<leaf>")
+        return node
+
+
+def _blanked(expr):
+    return ast.dump(_Blank().visit(ast.parse(ast.unparse(expr))))
+
+
+def _called_name(func):
+    return (func.attr if isinstance(func, ast.Attribute)
+            else func.id if isinstance(func, ast.Name) else "")
+
+
+def _innermost(tree):
+    """{id(node): INNERMOST enclosing function}, or None at module level.
+
+    ⚠️ NOT `for fn in ast.walk(tree): for node in ast.walk(fn)`, which is what
+    the first version of census B did. That visits every sentence once per
+    ENCLOSING def, so a sentence inside a nested function was classified twice -
+    once against the inner scope and once against the outer - and the two
+    classifications are not obliged to agree. The rows were de-duplicated
+    afterwards, which hid the double visit rather than removing it.
+    """
+    m = {}
+
+    def rec(node, fn):
+        for child in ast.iter_child_nodes(node):
+            f = (child if isinstance(child, (ast.FunctionDef,
+                                             ast.AsyncFunctionDef)) else fn)
+            m[id(child)] = f
+            rec(child, f)
+
+    rec(tree, None)
+    return m
+
+
+def _spec(fv):
+    """The FORMAT SPEC of one interpolation, as text; '' when there is none.
+
+    ⚠️ IT IS PRINTED BESIDE EVERY PAIR BECAUSE IT IS THE ONE CHEAP TYPE SIGNAL
+    THIS SCAN HAS, and gap 4 of the second list below is exactly about the pairs
+    that do not share
+    one. `{self.requested_w:+.0f}` beside `{self.applied_w:+.0f}` is two floats
+    rendered identically - a transposition there is silent and reads as a fact.
+    `{self.limit_w:.0f}` beside `{self.bound}` is a float beside a string: a
+    transposition there prints `rating max_w W`, which is visibly broken rather
+    than quietly wrong. Same row in this census, very different hazard, and the
+    reader cannot tell them apart without this column.
+    """
+    if fv.format_spec is None:
+        return ""
+    return "".join(str(v.value) if isinstance(v, ast.Constant) else "{...}"
+                   for v in fv.format_spec.values)
+
+
+def _same_shape_pairs(node):
+    """Pairs of interpolations in ONE f-string that are exactly one leaf apart."""
+    fvs = [v for v in node.values if isinstance(v, ast.FormattedValue)]
+    for x, y in itertools.combinations(fvs, 2):
+        ua, ub = ast.unparse(x.value), ast.unparse(y.value)
+        if ua == ub:
+            continue
+        if _blanked(x.value) != _blanked(y.value):
+            continue
+        yield ua, ub, _spec(x), _spec(y)
+
+
+def _sentences():
+    """(path, innermost fn, JoinedStr, sink) for every f-string in app/."""
+    for path in sorted(APP.glob("*.py")):
+        tree = ast.parse(path.read_text())
+        inner = _innermost(tree)
+        for node in ast.walk(tree):
+            if not isinstance(node, ast.JoinedStr):
+                continue
+            fn = inner.get(id(node))
+            if fn is None:
+                continue
+            yield path, fn, node, _sink_of(fn, node)
+
+
+def scan_caller():
+    rows = []
+    for path, fn, node, sink in _sentences():
+        # ⚠️ MESSAGE SINKS ONLY, AND THE FIRST VERSION OF THIS CENSUS SAID
+        # "anything but a RETURN". That let in `p1.py`'s
+        # `self.url = f"http://{self.host}:{self.port}…"` - an f-string that is
+        # DATA, used to make a request, where a transposition is an ordinary
+        # behavioural change every check can see. A formatted string is only in
+        # this family when its only consumer is a person. RETURN is not OTHER
+        # though, and treating it as if it were is what census C below fixes.
+        if sink != "MESSAGE":
+            continue
+        for ua, ub, sa, sb in _same_shape_pairs(node):
+            rows.append((path.name, node.lineno, fn.name, ua, ub, sa, sb))
+    return sorted(set(rows), key=lambda r: (r[0], r[1], r[3]))
+
+
+# =============================================================================
+# CENSUS C - THE SENTENCE THE OBJECT RETURNS ABOUT ITSELF
+# =============================================================================
+# ⚠️ SAFETY-38 ROUND 4. CENSUS A AND CENSUS B BETWEEN THEM COVERED ONE
+# SYNTACTIC SINK AND CALLED IT THE FAMILY. Every member either census reported
+# was a sentence APPENDED, ASSIGNED to a `reason`-shaped attribute, or passed as
+# a LOG ARGUMENT. Not one was a sentence that is RETURNED. Census A had a RETURN
+# bucket, but only for a callee formatting its own PARAMETERS - so a method
+# formatting its own ATTRIBUTES and handing the string back was invisible to
+# both, and `describe()` / `explain()` / the reason-builders are precisely where
+# this codebase keeps its operator sentences. Two live members were sitting in
+# that hole:
+#
+#   clamp.py    ClampResult.describe()   requested_w <-> applied_w
+#   peakguard.py PeakDecision.explain()  projected_w <-> ceiling_w
+#
+# Worse than the gap: it was in NONE of the five blind spots this file prints
+# about itself. A tool that asserts a completeness it does not have is the
+# recurring defect in a new hat, and the list at the bottom now names its sinks.
+#
+# THE TEST is census B's - one f-string, two interpolations one leaf apart - run
+# over the RETURN sink, plus one thing census B never needed: A RETURNED STRING
+# IS NOT YET A MESSAGE. `store.unit_key()` and `mqtt.unit_state_key()` return
+# f-strings too, and swapping there renames a store key and an MQTT topic, which
+# every ordinary check can see (MAINT-05 is the card about that). So the sink of
+# a returned sentence is RESOLVED THROUGH ITS CALL SITES: the string is in this
+# family only when some caller in `app/` feeds it to an operator.
+
+
+def _return_consumers(func_name, depth=0, seen=frozenset()):
+    """[(site, sink, verdict)] - where the STRING RETURNED BY `func_name` goes.
+
+    One hop is not enough: `Resolution.explain()` is returned again by wrappers
+    that are themselves logged, so a call site whose own sink is RETURN is
+    resolved by recursing on the ENCLOSING function's name, bounded by `depth`
+    and by `seen` so mutual recursion cannot loop.
+
+    ⚠️ THE MATCH IS ON THE BARE METHOD NAME, exactly as `call_sites()` above,
+    and `explain` is the name of at least four unrelated methods in this tree
+    (`PeakDecision`, `UnitPlan`, `Resolution`, the maintenance migration
+    report). So this OVER-collects sites, which pushes a verdict towards
+    MESSAGE. That is the deliberate direction for a census whose measured
+    failure has twice been under-reporting - but it means the verdict is a
+    PROMPT TO READ THE SITES PRINTED BESIDE IT, not a proof.
+    """
+    if func_name in seen or depth > 2:
+        return []
+    seen = seen | {func_name}
+    out = []
+    for path in sorted(APP.glob("*.py")):
+        tree = ast.parse(path.read_text())
+        inner = _innermost(tree)
+        for node in ast.walk(tree):
+            if not isinstance(node, ast.Call):
+                continue
+            if _called_name(node.func) != func_name:
+                continue
+            fn = inner.get(id(node))
+            if fn is None:
+                continue
+            sink = _sink_of(fn, node)
+            label = f"{path.name}:{node.lineno} `{ast.unparse(node.func)}`"
+            if sink == "RETURN":
+                sub = _return_consumers(fn.name, depth + 1, seen)
+                if any(v == "MESSAGE" for _l, _s, v in sub):
+                    verdict = "MESSAGE"
+                elif not sub:
+                    verdict = "UNRESOLVED"
+                else:
+                    verdict = "OTHER"
+                sink = f"RETURN by {fn.name}() -> {verdict}"
+            else:
+                verdict = sink
+            out.append((label, sink, verdict))
+    return sorted(set(out))
+
+
+def scan_returned():
+    """Census C rows: a returned sentence, two interpolations one leaf apart."""
+    rows = []
+    for path, fn, node, sink in _sentences():
+        if sink != "RETURN":
+            continue
+        pairs = list(_same_shape_pairs(node))
+        if not pairs:
+            continue
+        sites = _return_consumers(fn.name)
+        if any(v == "MESSAGE" for _l, _s, v in sites):
+            verdict = "MESSAGE"
+        elif not sites:
+            verdict = "UNRESOLVED - no call site inside app/"
+        else:
+            verdict = "OTHER"
+        for ua, ub, sa, sb in pairs:
+            rows.append(dict(module=path.name, line=node.lineno, func=fn.name,
+                             a=ua, b=ub, spec_a=sa, spec_b=sb,
+                             verdict=verdict, sites=sites))
+    return sorted(rows, key=lambda r: (r["module"], r["line"], r["a"]))
+
+
+# ⚠️ THE UNIT OF COVERAGE IS THE CALL SITE, NOT THE FUNCTION - which is the
+# whole lesson of SAFETY-38 round 3. `SignWatchdog.evaluate()` had its operand
+# order pinned and the defect still shipped, because the pin was on the call two
+# lines below the one a one-inverter roster actually reaches. So a family member
+# is reported WITH EVERY PLACE IT IS CALLED.
+def call_sites(name):
+    out = []
+    for path in sorted(APP.glob("*.py")):
+        tree = ast.parse(path.read_text())
+        for node in ast.walk(tree):
+            if not isinstance(node, ast.Call):
+                continue
+            if _called_name(node.func) != name:
+                continue
+            # ⚠️ THE RECEIVER IS PRINTED, because matching on the bare
+            # attribute name conflates methods: `evaluate` is the name of
+            # SAFETY-02's, SAFETY-18's and SAFETY-31's watchdogs alike, and
+            # a list of four lines with no receiver tells a reader nothing
+            # about which detector they are looking at. `inv.sign_wd` and
+            # `self.freeze_wd` are the disambiguation, and they are the
+            # caller's own words.
+            out.append(f"{path.name}:{node.lineno} `{ast.unparse(node.func)}`")
+    return out
+
+
+def lazy_log_sites():
+    """Log calls with a %-format template and >=2 substitution ARGUMENTS.
+
+    ⚠️ THE SIZE OF THE LARGEST HOLE, MEASURED RATHER THAN ASSERTED. The
+    NOT-SCANNED list below used to end "and app/ uses that form", which is a
+    claim about the tree with no number on it - the exact shape this card has
+    spent four rounds arguing against. `_LOG.error("%s ... %s", a, b)` puts both
+    operands in ARGUMENTS, so no f-string census here can ever reach them, and
+    transposing the two costs the same zero bytes. This counts them.
+    """
+    out = []
+    for path in sorted(APP.glob("*.py")):
+        tree = ast.parse(path.read_text())
+        for node in ast.walk(tree):
+            if not isinstance(node, ast.Call):
+                continue
+            if _called_name(node.func) not in _LOG_SINKS or len(node.args) < 3:
+                continue
+            head = node.args[0]
+            tmpl = ""
+            if isinstance(head, ast.Constant) and isinstance(head.value, str):
+                tmpl = head.value
+            elif isinstance(head, ast.BinOp) or isinstance(head, ast.JoinedStr):
+                tmpl = ast.unparse(head)
+            if tmpl.count("%") >= 2:
+                out.append((path.name, node.lineno,
+                            f"{path.name}:{node.lineno} "
+                            f"`{ast.unparse(node.func)}` with "
+                            f"{len(node.args) - 1} args"))
+    return [r[2] for r in sorted(out)]
+
+
+def _pair_line(sa, sb):
+    same = sa == sb
+    return (f"      format spec: '{sa}' / '{sb}'  -> "
+            + ("SAME - two values rendered alike, so a transposition is "
+               "SILENT and reads as a fact"
+               if same else
+               "DIFFERENT - likely mixed types, so a transposition is more "
+               "likely to look broken than to lie (gap 4 below)"))
+
+
+def main():
+    quiet = "--quiet" in sys.argv
+    rounds = build_fixpoint()
+    rows = scan()
+    fam = [r for r in rows if r["symmetric"] and "MESSAGE" in r["sinks"]
+           and "RETURN" not in r["sinks"]]
+    valued = [r for r in rows if r["symmetric"] and "RETURN" in r["sinks"]]
+    print("SYMMETRIC-PREDICATE FAMILY - argument order load-bearing for a "
+          "MESSAGE only")
+    print("=" * 78)
+    print(f"fixpoint reached after {rounds} round(s); "
+          f"{sum(len(v) for v in _SYM.values())} interchangeable positional "
+          f"and {sum(len(v) for v in _SYM_KW.values())} keyword pair(s) "
+          f"across {len(set(_SYM) | set(_SYM_KW))} function(s) in app/")
+    print(f"functions formatting >=2 of their own parameters into one "
+          f"sentence: {len(rows)} pair(s)")
+    print(f"of those, pairs whose SWAP LEAVES EVERY DECISION IDENTICAL: "
+          f"{len(fam) + len(valued)}")
+    print(f"  ...of which the sentence is RETURNED (so the swap is a VALUE "
+          f"change an ordinary check can see): {len(valued)}")
+    print(f"  ...and the sentence goes ONLY TO AN OPERATOR - THE FAMILY: "
+          f"{len(fam)}")
+    print()
+    print("THE FAMILY - a swap here is invisible to every behavioural check "
+          "BY CONSTRUCTION:")
+    for r in sorted(fam, key=lambda r: (r["module"], r["line"])):
+        kind = ("POSITIONAL - a transposition at a call site costs ZERO BYTES"
+                if r["positional"] else
+                "KEYWORD-ONLY at the definition - a transposition has to be "
+                "written out by name, which is not free and not silent")
+        print(f"  {r['module']}:{r['line']}  {r['func']}()   pair "
+              f"({r['a']}, {r['b']})")
+        print(f"      sentence at line(s): "
+              f"{', '.join(f'{l} -> {s}' for l, s in r['msg_lines'])}")
+        print(f"      {kind}")
+        sites = call_sites(r["func"])
+        print(f"      CALL SITES ({len(sites)}) - each one is a separate pin, "
+              f"and the receiver says which detector it is:")
+        for site in sites or ["(none inside app/)"]:
+            print(f"        {site}")
+    print()
+    print("SYMMETRIC, BUT THE SENTENCE IS THE RETURN VALUE - READ THIS BUCKET "
+          "BY HAND.")
+    print("A returned string is sometimes a KEY (a swap renames a store key or "
+          "an MQTT topic,")
+    print("which is behaviour every ordinary check can see - MAINT-05 is the "
+          "card about it)")
+    print("and sometimes a SENTENCE (a swap is message-only after all, and it "
+          "IS this family):")
+    for r in sorted(valued, key=lambda r: (r["module"], r["line"])):
+        print(f"  {r['module']}:{r['line']}  {r['func']}()   pair "
+              f"({r['a']}, {r['b']})")
+    print()
+    print("=" * 78)
+    print("CENSUS B - SENTENCES THE CALLER BUILDS, interpolating two values of "
+          "the SAME SHAPE")
+    print("A transposition inside one of these is ZERO BYTES and no predicate "
+          "is involved at")
+    print("all, so nothing behavioural can ever see it. Same rule: assert the "
+          "ORDERED PAIR.")
+    cb = scan_caller()
+    print(f"candidates: {len(cb)}")
+    for mod, line, fn, ua, ub, sa, sb in cb:
+        print(f"  {mod}:{line}  in {fn}()")
+        print(f"      {ua}   <->   {ub}")
+        print(_pair_line(sa, sb))
+    print()
+    print("=" * 78)
+    print("CENSUS C - SENTENCES AN OBJECT RETURNS ABOUT ITSELF  (SAFETY-38 "
+          "round 4)")
+    print("A method formatting its OWN ATTRIBUTES and RETURNING the string was "
+          "in neither")
+    print("census above: census A only reads a callee's PARAMETERS, census B "
+          "only scored a")
+    print("MESSAGE sink. The verdict below is resolved through the CALL SITES "
+          "of the")
+    print("returning method - a returned string is only in this family once "
+          "some caller")
+    print("hands it to an operator (contrast store.unit_key(), whose return "
+          "value is a KEY).")
+    cc = scan_returned()
+    fam_c = [r for r in cc if r["verdict"] == "MESSAGE"]
+    hot = [r for r in fam_c if r["spec_a"] == r["spec_b"]]
+    print(f"returned sentences with a same-shape pair: {len(cc)} pair(s); "
+          f"{len(fam_c)} reach an operator;")
+    print(f"of those, {len(hot)} ALSO share a format spec - two values "
+          f"rendered alike, which is")
+    print("the hazard gap 4 below names: a transposition there is silent and "
+          "reads as a fact.")
+    print()
+    print("*** = reaches an operator AND shares a format spec - THE ACTIONABLE "
+          "SUBSET")
+    print(" !  = reaches an operator, specs differ (a swap is likelier to look "
+          "broken)")
+    print("    = does not reach an operator, or could not be resolved")
+    # grouped by the sentence, so the CONSUMERS list is printed once per
+    # method rather than once per pair - the ungrouped form was 20 identical
+    # lines under each of six pairs and nobody reads that.
+    for key in sorted({(r["module"], r["line"], r["func"]) for r in cc}):
+        mod, line, fname = key
+        group = [r for r in cc if (r["module"], r["line"], r["func"]) == key]
+        v = group[0]["verdict"]
+        print(f"  {mod}:{line}  {fname}()   verdict: {v}")
+        for r in group:
+            mark = ("***" if r["verdict"] == "MESSAGE"
+                    and r["spec_a"] == r["spec_b"]
+                    else " ! " if r["verdict"] == "MESSAGE" else "   ")
+            print(f"    {mark} {r['a']}   <->   {r['b']}")
+            print(f"        {_pair_line(r['spec_a'], r['spec_b']).strip()}")
+        if not quiet:
+            sites = group[0]["sites"]
+            print(f"      CONSUMERS ({len(sites)}) - bare-name match, so read "
+                  f"the receiver:")
+            for label, sink, _v in sites or [("(none inside app/)", "", "")]:
+                print(f"        {label}  -> {sink}")
+    print()
+    print("=" * 78)
+    print("WHAT THIS SCANS, AND WHAT IT DOES NOT - stated because round 4's "
+          "blocker was")
+    print("a completeness this file ASSERTED and did not have. The sink "
+          "classifier is a")
+    print("syntactic walk up the parent chain plus ONE step of local data "
+          "flow, and it")
+    print("recognises exactly these sinks and no others:")
+    print(f"  SCANNED as a MESSAGE : a call to {sorted(_LOG_SINKS)}")
+    print("                         ...or to `append`; a `raise`; an "
+          "assignment to an")
+    print(f"                         attribute or local named {sorted(_MSG_ATTRS)}")
+    print("                         ...or to a local that is then interpolated "
+          "into one of")
+    print("                         those (the one data-flow step).")
+    print("  SCANNED as a RETURN  : census C - resolved through the returning "
+          "method's")
+    print("                         call sites, one hop plus two of recursion.")
+    print("  NOT SCANNED AT ALL, and each of these can hold a member:")
+    lazy = lazy_log_sites()
+    print("    * `%s`-style lazy logging - `_LOG.error('%s ... %s', a, b)`. The "
+          "arguments")
+    print("      are not an f-string, so no census here looks at them, and a "
+          "transposition")
+    print("      of two `%s` arguments is the same zero-byte edit. THIS IS THE "
+          "LARGEST")
+    print(f"      REMAINING HOLE, and it is MEASURED, not asserted: "
+          f"{len(lazy)} such call(s)")
+    print(f"      in app/, across "
+          f"{len({s.split(':')[0] for s in lazy})} module(s). None of them is "
+          f"scanned by anything")
+    print("      above. Listed here so the size of the hole is a number:")
+    for site in lazy or ["(none)"]:
+        print(f"        {site}")
+    print("    * `.format()`, `%`-formatting, and sentences built by `+` or "
+          "`.join()` out of")
+    print("      non-f-string pieces.")
+    print("    * A sentence that leaves the function inside a DICT, LIST or "
+          "dataclass and is")
+    print("      rendered somewhere else - the one data-flow step is local and "
+          "follows only")
+    print("      a bare Name.")
+    print("    * `yield`ed sentences, and sentences stored on an object by any "
+          "attribute")
+    print(f"      name outside {sorted(_MSG_ATTRS)}.")
+    print("    * Anything outside `app/`: `sim/`, `tools/`, `web.py`'s "
+          "templates, the")
+    print("      translations JSON, the firmware, the witness.")
+    print()
+    print("WHAT IT CAN SEE BUT GETS WRONG - the shape of each gap, named "
+          "rather than")
+    print("rounded off:")
+    print("  1. SEMANTIC symmetry no canonicaliser above spells. The list of "
+          "commutative")
+    print("     forms is finite and hand-written; a function symmetric only "
+          "through a form")
+    print("     not on it is REJECTED and never appears. This under-reports.")
+    print("  2. In CENSUS B and C, two interpolated values of the same KIND "
+          "that are not the")
+    print("     same SHAPE - `a.lo` beside `hi`, or one of them behind a local "
+          "variable.")
+    print("     Only one-leaf-apart expressions are paired.")
+    print("  3. WHETHER each call site is pinned. The sites are listed above; "
+          "whether a")
+    print("     check asserts the ORDERED PAIR at each one is a fact about "
+          "`test_*.py` and is")
+    print("     recorded in DECISIONS/SAFETY-38-site-standing-pin.md section "
+          "7. Call sites")
+    print("     outside `app/` are not listed either, and every site list here "
+          "matches on the")
+    print("     bare METHOD NAME - three watchdogs are all called `evaluate` "
+          "and at least")
+    print("     four unrelated classes have an `explain()` - so the receiver is "
+          "printed")
+    print("     beside each one and a reader has to pick.")
+    print("  4. ⚠️ IT CAN ALSO OVER-REPORT, IN ONE EXACT WAY. The sentence is "
+          "ERASED before")
+    print("     census A's comparison, so a swap that would make the FORMATTING "
+          "ITSELF fail")
+    print("     - a `DAY_NAMES[start]` where `start` is 1320 - is scored as "
+          "'changes no")
+    print("     decision'. `_raise_gap`'s (start, weekday) pairs are that. The "
+          "hazard is a")
+    print("     SAME-TYPED pair, which is why every census B and C row now "
+          "prints whether")
+    print("     the two format specs match.")
+    print("  5. CENSUS C's verdict is a bare-name resolution (gap 3) and "
+          "therefore reads")
+    print("     MESSAGE too readily. Every verdict is printed with the sites "
+          "that produced")
+    print("     it; a MESSAGE verdict is a prompt to read them, not a proof.")
+
+
+if __name__ == "__main__":
+    main()