SAFETY-12 review: name the safety claim that could not fire, and fix two figures

Review fixes.

A. test_loop.py takes 73 s, not the ~35 s claimed in three places. That number
is the whole defence against a future developer deleting a slow test, so it was
understated by 2x in exactly the place it matters. Corrected - and it is now
~95 s (measured 93 s), because this commit adds the scenario below rather than
trimming windows to make an inconvenient number smaller. Both call sites carry
an instruction to re-measure if the windows change.

B. "242 checks" was test_p1's own count quoted as the total for all five
suites. The real figure is 395 across the five, plus 14 here.

And the finding this PR should have led with. stale_input_s and the
`inputs missing -> 0 W` claim both live INSIDE cycle(), so pre-fix, on a meter
whose value happened to repeat, that claim could not fire at all. Constant
meter, SoC entity dying at t=4 s, one binary:

  pre-fix   final target 220.0 W, reason 'loop -> 220 W'
  post-fix  final target   0.0 W, reason 'safety -> 0 W'

The old controller held 220 W through the whole input outage with its status
line still reading loop -> 220 W, and layer 1 does not cover that on a
`meter_source: off` install - no P1 age sensor is published, so the firmware has
nothing to veto on, while the heartbeat keeps its watchdog fed. The pre-fix
behaviour was not "holds a stale command safely"; it was a failsafe a repeating
meter switched off. Asserted in test_loop.py, both halves.

Three points of reasoning tightened, none of them wrong before:

- the re-tune is unreachable by construction, not merely by the reset: the
  combined cycle rate is max(arrival rate, 1/floor), never the sum, and 1/15 s
  is strictly slower than the ~1/5 s arrival rate. That holds only while the
  floor exceeds the meter's update interval - and the schema minimum of 5 s is
  exactly the reference meter's interval. Flagged for validate.py, not fixed
  here.
- the ~11 s lower bracket is not only a dropped poll: a 5.0 s poller against a
  4.97 s meter beats, so about every 14 minutes the poller steps over an update
  entirely. Reaching 15 s takes a beat-skip AND a failed poll.
- the "freshness is decided upstream" guarantee is transport-conditional. On
  `meter_source: off` the grid figure comes straight from hass.number() with no
  age gate. Running the full law is still right; the claim is narrower than it
  was stated.

The 15 s default is not independently justified - it rests on the firmware's
30 s ingest veto and moves if that ever does. Said beside the constant.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Du77usMj8XNKNFZGmUiWDa

goodwe_controller/app/main.py

@@ -345,17 +345,33 @@ class Controller:
         # ⚠️ SAFETY-12. The floor is a DEADLINE ON THE GAP BETWEEN CYCLES, not a
         # second scheduler running alongside the arrival trigger. Every cycle
         # resets it, whichever trigger fired, so on a healthy changing meter it
-        # never elapses and not one existing cycle moves - no beat frequency
-        # between the two triggers, no doubled cycle rate, and therefore no
+        # never elapses and not one existing cycle moves - and therefore no
         # change to the per-cycle gain the tuning was measured against.
         #
-        # Why it has to exist: `self.grid != last_grid` alone means a meter that
-        # repeats a value runs NO control cycles at all, while the heartbeat
-        # below keeps re-emitting the last command and the firmware keeps
-        # putting it on the wire - so every indicator reads healthy while the
-        # loop has not evaluated and the load may have moved underneath it.
-        # Measured on the rig during TEL-05: 70 s at a literally constant
-        # 350.0 W, 14 arrivals, zero cycles.
+        # That is true twice over, and the second reason is the sturdier one:
+        # the combined cycle rate is max(arrival rate, 1/floor), never the sum.
+        # At the defaults 1/15 s is strictly slower than the ~1/5 s arrival
+        # rate, so even a floor that raced the arrivals could not push the loop
+        # past its nominal healthy rate. The re-tune is unreachable by
+        # construction, not merely by the reset. ⚠️ That argument holds only
+        # while floor > the meter's update interval - which is why the schema
+        # minimum of 5 s deserves the second look validate.py has not given it
+        # yet: 5 s IS the reference meter's interval, i.e. the one configurable
+        # value that would double the cycle rate.
+        #
+        # Why it has to exist, and it is not only about latency: `self.grid !=
+        # last_grid` alone means a meter that repeats a value runs NO control
+        # cycles at all. The heartbeat below keeps re-emitting the last command
+        # and the firmware keeps putting it on the wire, so every indicator
+        # reads healthy - and, worse, the `inputs missing -> 0 W` claim lives
+        # INSIDE cycle(), so on a repeating meter THAT SAFETY CLAIM CANNOT FIRE.
+        # Demonstrated in test_loop.py: constant meter, SoC entity dies at t=4 s,
+        # and the pre-fix controller holds 220 W through the whole outage with
+        # the status line still reading "loop -> 220 W". Layer 1 does not cover
+        # it on a `meter_source: off` install either - no P1 age sensor is
+        # published, so the firmware has nothing to veto on. Measured on the rig
+        # during TEL-05: 70 s at a literally constant 350.0 W, 14 arrivals, zero
+        # cycles.
         #
         # This is NOT a freeze detector, and deliberately so - see
         # HomeWizardLocalSource.unchanged_s for why one cannot be built here (at
@@ -363,6 +379,13 @@ class Controller:
         # so any freeze threshold false-trips at the exact operating point we
         # run at). Nothing here decides whether a repeated reading is true. It
         # only stops "the number is the same" from meaning "do not think".
+        #
+        # ⚠️ THE 15 s DEFAULT HAS A CEILING IT DOES NOT OWN. It is under
+        # validate.FIRMWARE_INGEST_VETO_S (30 s) and under meter_max_age_s on
+        # purpose, so the loop re-decides at least twice inside any window in
+        # which layer 1 might otherwise be the only thing deciding. If the
+        # firmware's veto ever moves, this default moves with it - it is not
+        # independently justified at 15.
         floor = float(self.o.get("cycle_floor_s", 15))
         last_cycle = None
         while not self.stopping:
@@ -375,13 +398,23 @@ class Controller:
                 last_grid = self.grid
                 last_cycle = now_mono
                 # ⚠️ The FULL cycle, not a degraded one. A floor cycle runs the
-                # same law on the same inputs as an arrival cycle, because the
-                # freshness question is already answered upstream and answered
-                # harder: past `meter_max_age_s` (30 s) p1.net_w is None, which
-                # is "inputs missing", which becomes a P_SAFETY 0 W claim. So a
-                # floor cycle can only ever run on a reading this system already
-                # calls fresh - it cannot run the PI on a 60 s old figure,
-                # because at 60 s there is no figure. And the integrator
+                # same law on the same inputs as an arrival cycle, because in P1
+                # mode the freshness question is already answered upstream and
+                # answered harder: past `meter_max_age_s` (30 s) p1.net_w is
+                # None, which is "inputs missing", which becomes a P_SAFETY 0 W
+                # claim. So a floor cycle cannot run the PI on a 60 s old
+                # figure, because at 60 s there is no figure.
+                #
+                # ⚠️ THAT GUARANTEE IS TRANSPORT-CONDITIONAL, and saying so
+                # matters more than the guarantee: with `meter_source: off`,
+                # read_inputs() takes self.grid straight from hass.number() with
+                # NO age gate at all, so a Home Assistant entity that has gone
+                # quiet reads as a current value on that path with or without
+                # this change. Running the full law is still the right choice
+                # there - the alternative is a degraded second law reasoning
+                # about an age nobody measured - but the floor does not make
+                # that path fresh, and nothing here should be read as claiming
+                # it does. And the integrator
                 # advances per CYCLE, not per second (control.py), so bounding
                 # the gap bounds the accumulation: at most one extra
                 # gain x error per floor interval, under the same