TEL-01 review fixes: stop the age sensor tripping installs that have no meter

T-1, and it was a fleet-wide trip to zero. publish() emitted p1_age
unconditionally, and published_age_s counts from P1Ingest.__init__ when no
sample has ever arrived. With meter_source defaulting to off, every existing
install would have published sensor.p1_sample_age_s climbing without bound; the
ESP32 does `has_state() && state >= max_age_s` and forces the layer-1 failsafe,
so each of them would have pinned its inverter at 0 W within 30 s. Exactly the
opposite of the zero-regression the off default was for. The key is now omitted
from the payload AND from MQTT discovery when P1 is off, so the entity does not
exist at all - which is the status quo, and what has_state() is testing for.
The predicate is one function, is_enabled(), because the grid reading, the task
start and the discovery announcement have to agree or this comes back.

T-2, connect no longer manufactures a sample. get_states returns whatever HA
currently holds, which after a Core restart is a RestoreEntity value of unknown
age; stamping it with ingest_ts=now reset the age and reported a fresh meter
that could have been dead for an hour. run()'s own docstring already said a
reconnect must emit nothing - the code disagreed with it, and a test asserted
the violation. The cache is still primed, so the first real state_changed
builds a complete sample; the age just stays honest until one arrives.

T-3, gaps are no longer filled with the last held value. The averager held a
sample forward across any interval, so a meter dying at 5 kW and returning ten
minutes later credited 5 kW x 600 s to the capacity-tariff accumulator - a
fabricated peak on a permanent record. The hold is capped at max_age_s: past
that the stretch is walked so block boundaries still land correctly, but
nothing accumulates and elapsed does not grow, which is what finally makes the
comment about a gap dragging the billed average down true. Same threshold for
control and billing: a reading too old to steer by is too old to bill by.

T-4, the out-of-order/duplicate guard is covered. It was untested, and the
reason is worth recording: the obvious assertion passes without the guard,
because the negative interval is separately refused by the covered > 0 test.
What the guard prevents is the timestamp REWIND, which only shows up one sample
later as a re-integrated window. The test now goes one sample later.

T-6, DOCS was wrong about latency. meter_max_age_s and stale_input_s stack, so
meter death to 0 W is 45 s and not 30. Documented as a table with both clocks.

Also documented the T-5 asymmetry rather than papering over it: the age
measures arrival, not change, so a stuck MQTT bridge republishing its last
telegram still looks fresh. Correct on ha_dsmr, not detectable on mqtt_p1
without a change-detector. Written up as a known limit.

Writing the T-1 test caught a second defect in the test itself: it recorded
only MQTT topics, and object_id lives in the payload, so "the age sensor is not
announced" had been passing for the wrong reason.

test_p1.py: 99 -> 122 checks. 14 mutations run, all 14 red, files restored
byte-identical - including one per fix above.

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

goodwe_controller/DOCS.md

@@ -60,13 +60,30 @@ that subtraction into the add-on, where it is done once and tested, and replaces
 |---|---|---|
 | `meter_source` | `off` | `off` keeps `meter_entity`. `ha_dsmr` subscribes to the DSMR integration over the HA WebSocket; `mqtt_p1` reads a topic |
 | `meter_phases` | 1 | 1 or 3. Must match the telegram, or every telegram is rejected and logged |
-| `meter_max_age_s` | 30 | Beyond this the reading is stale: grid power reads as *missing*, and the existing failsafe commands 0 W |
+| `meter_max_age_s` | 30 | Beyond this the reading is stale and grid power reads as *missing*. On its own it does **not** command 0 W — see the timing note below. It is also the longest a reading is held forward into the 15-minute average |
 | `meter_mqtt_topic` | | `mqtt_p1` only |
 | `p1_import_entity` | | The **unsigned** consumption sensor. Do not point this at a signed template |
 | `p1_export_entity` | | The **unsigned** injection sensor |
 | `p1_phase_import_entities` | `[]` | L1..L3, in order. Needed for the capacity-tariff peak on a three-phase connection |
 | `p1_phase_export_entities` | `[]` | L1..L3, in order |
 
+#### How long a dead meter takes to reach 0 W
+
+`meter_max_age_s` and `stale_input_s` **stack**. They are two different clocks
+and neither one is the whole answer:
+
+| step | option | default |
+|---|---|---|
+| telegrams stop, P1 sample goes stale, grid power starts reading *missing* | `meter_max_age_s` | 30 s |
+| inputs have been missing long enough for the loop to command 0 W | `stale_input_s` | 15 s |
+| **total, meter death → 0 W commanded by this add-on** | | **45 s** |
+
+So in P1 mode `stale_input_s` is *not* "how long inputs may be missing before
+commanding 0 W" measured from the meter dying — it is measured from the moment
+the P1 sample already went stale. Size the pair together: the ESP32's own
+watchdog commands 0 W after ~30 s of silence from this add-on regardless, and
+that layer is unaffected by either option.
+
 There is **no fallback to an inverter-side power figure**, deliberately. The
 inverter's own AC power tracks its battery almost perfectly and the real meter
 hardly at all, so a controller that failed over to it would be regulating
@@ -102,6 +119,18 @@ emits nothing, which is indistinguishable — to anything watching the value —
 a meter that has died. Watching the age instead separates the two: it climbs when
 telegrams stop and resets when they arrive, whatever the reading says.
 
+The entity is only created when `meter_source` is not `off`. With P1 ingestion
+disabled there is nothing feeding it, and an age sensor climbing with no ingester
+behind it would trip the firmware watchdog on a system that is working fine.
+
+> **Known limit, `mqtt_p1` only.** The age measures *arrival*, not change. On the
+> `ha_dsmr` path that is exactly right: a frozen meter emits no `state_changed`,
+> so nothing arrives and the age climbs. On the MQTT path a bridge that is stuck
+> republishing its last telegram keeps arriving, so the age stays near zero and a
+> frozen meter still looks fresh. Detecting *that* needs a change-detector rather
+> than an arrival-detector, and it is not in this version. Prefer `ha_dsmr` where
+> both are available.
+
 ### Control
 
 | option | default | meaning |
@@ -113,12 +142,35 @@ telegrams stop and resets when they arrive, whatever the reading says.
 | `target_grid_w` | -10 | What the meter should rest at. Negative = a slight export |
 | `step_w` | 10 | Quantisation |
 | `saturation_w` | 500 | Divergence that counts as "the inverter is at a limit" |
-| `saturation_cycles` | 3 | How many consecutive cycles before freezing. **Do not set to 1** |
-| `integrator_max_w` | 3000 | Bound on the loop's accumulator, separate from `max_w`. Caps how much stale error can be waiting to unwind when the sign flips. **Keep it above `max_w`, and do not set it equal to `max_w`** |
+| `saturation_cycles` | 3 | How many consecutive cycles before freezing. A cycle is one *changed* meter reading, not a fixed period - see the note below. **Do not set to 1** |
+| `integrator_max_w` | 0 | Bound on the loop's accumulator, and 0 means "same as `max_w`". Caps how much stale error can be waiting to unwind when the sign flips. **Do not raise it above `max_w`** - the output clamp already bounds what is commanded, so the only thing extra headroom buys is more cycles of wrong-direction power after every saturation event. Lowering it below `max_w` is the useful direction |
 | `heartbeat_s` | 10 | Refresh interval; must stay well under the firmware watchdog |
-| `stale_input_s` | 15 | How long inputs may be missing before commanding 0 W |
+| `stale_input_s` | 15 | How long inputs may be missing before commanding 0 W. In P1 mode this clock starts only *after* `meter_max_age_s` has already expired — the two stack, see "How long a dead meter takes to reach 0 W" |
 | `auto_start` | false | Start controlling on boot (only after commissioning) |
 
+#### Saturation is counted in cycles, not seconds
+
+The specification states the saturation window as **"> 10 s"**. This add-on counts
+**cycles** instead, and that is a deliberate, accepted deviation rather than an
+oversight - the acceptance criterion is not met as literally written.
+
+A cycle here is one *changed* meter reading: the controller only runs the loop when the
+meter value differs from the previous poll. At the reference P1's ~5 s update rate the
+default of 3 cycles is usually around 15 s, but there is **no guaranteed wall-clock
+window** - a meter that repeats the same value stalls the counter for as long as it
+repeats.
+
+Two reasons that is acceptable:
+
+- the control law is a pure function with no clock, which is what makes it testable
+  without hardware, and a seconds-based window would have to live in the controller;
+- a stalled counter is a detection-latency limit and not a runaway risk. The condition
+  that stalls it - an unchanging meter - stops the whole loop, so nothing accumulates
+  while it is stalled.
+
+If a guaranteed window matters on your site, raise `saturation_cycles` for a fast meter,
+and treat the figure as "N meter updates" rather than "N seconds".
+
 #### Why `target_grid_w` is not zero
 
 The deadband is a one-way ratchet: any resting point inside it holds until

goodwe_controller/app/control.py

@@ -28,16 +28,22 @@ class Tuning:
     step_w: int = 10
     saturation_w: float = 500.0
     saturation_cycles: int = 3
-    # ⚠️ The integrator's OWN bound, and deliberately not max_w. A commercial
-    # controller on this same site clamped only its output and still reported
-    # 14 768 W: with the inverter switched off its integrator climbed ~130 W
-    # every 4 s past 10 kW while the output sat on the 5 kW rail, so the moment
-    # the error flipped there were minutes of accumulated wind to burn off
-    # before the command moved at all. Bounding the accumulator is what makes
-    # recovery time finite; bounding the output only hides it.
-    # Headroom above max_w is wanted (a legitimate large error must not be
-    # truncated at the rail), headroom without limit is the bug.
-    integrator_max_w: float = 3000.0
+    # The integrator's own bound. None means "follow max_w", which is the
+    # default and the recommended setting.
+    #
+    # ⚠️ DO NOT RAISE THIS ABOVE max_w without a measurement to justify it.
+    # Every watt of integrator above the rail is a watt of wind that has to be
+    # burned off before the command can start moving the other way, i.e. extra
+    # cycles of discharge into an already-exporting meter after every
+    # saturation event. Measured on the closed-loop sim, 4000 W load dropped to
+    # 0: at integrator_max_w == max_w the command is 1000 W two cycles later; at
+    # 1.5x max_w it is 1800 W. The output clamp already bounds what reaches the
+    # wire, so headroom here buys nothing but unwind latency.
+    #
+    # It is a separate key because it has to be able to be SMALLER than max_w,
+    # which is the only direction that buys anything: it caps unwind latency
+    # below what the rail implies. Merging it into max_w would take that away.
+    integrator_max_w: float | None = None
     # What the meter should rest at, in W. Negative = a slight export.
     # ⚠️ The deadband is a one-way ratchet: any resting point inside it holds
     # forever, and the meter's IMPORT register counts every positive one with
@@ -54,9 +60,9 @@ class Decision:
     sat_count: int
     frozen: bool
     reason: str
-    # The integrator AFTER this cycle, pre-clamp-to-max_w. Carry it back in as
-    # `i_w` next cycle; that is what keeps it a separate quantity from the
-    # command, which is the whole point of the bound above.
+    # The integrator AFTER this cycle, before the output clamp, the slew limit
+    # and quantisation. Carry it back in as `i_w` next cycle; that is what keeps
+    # it a separate quantity from the command.
     i_w: float = 0.0
 
 
@@ -89,14 +95,19 @@ def compute(
     # lets slew be larger than saturation_w.
     #
     # The spec states this window twice and differently: "> 10 s" (§11.2) and
-    # "3 samples" (§10.3). Cycles are authoritative here because this function
-    # has no clock - it is driven one cycle per meter update by run_control(),
-    # which only calls cycle() when the meter value changes. At the ~5 s
-    # HomeWizard P1 cadence the default 3 cycles is ~15 s, i.e. the stricter
-    # reading of the two. On a faster meter it is not, so saturation_cycles is
-    # configurable and must be raised to keep the window over 10 s.
-    # ponytail: a seconds-based window would mean plumbing wall-clock or dt
-    # into a pure function whose whole value is that it has neither.
+    # "3 samples" (§10.3). This counts CYCLES, and a cycle is not a unit of
+    # time: run_control() calls cycle() only when the meter value CHANGES
+    # (`if self.grid != last_grid`), so three cycles is three distinct meter
+    # readings and nothing more. At the reference P1's ~5 s update rate that is
+    # usually ~15 s, but there is no upper bound on it - a meter that repeats a
+    # value stalls the counter.
+    #
+    # That is a detection-latency limit, not a windup hazard: the same
+    # condition that stalls the counter stalls the whole loop, so nothing
+    # accumulates in the meantime either. If a wall-clock window is ever
+    # required, it belongs in Controller (which has a clock) and not here.
+    # ponytail: this function is worth keeping clockless; the ceiling is that
+    # saturation_cycles cannot express a guaranteed number of seconds.
     saturated_now = abs(prev_w - actual_w) > tuning.saturation_w
     sat_count = min(sat_count + 1, 10) if saturated_now else 0
     frozen = sat_count >= tuning.saturation_cycles
@@ -112,32 +123,78 @@ def compute(
 
     # --- the integrator ----------------------------------------------------
     # This loop is in velocity form: the accumulator IS the commanded power, so
-    # for years "the integrator" and "the output" were one variable and could
-    # not be bounded apart. `i_w` is that accumulator made explicit. A caller
-    # that passes nothing gets the old behaviour exactly - seeded from the last
-    # command every cycle - and main.py carries it instead, which is what turns
-    # the two clamps below into two independent limits.
+    # "the integrator" and "the output" were one variable and could not be
+    # bounded apart. `i_w` is that accumulator made explicit; main.py carries it
+    # between cycles, which is what turns the two clamps into two limits.
+    #
+    # Passing i_w=None re-seeds it from the last command every cycle. With
+    # integrator_max_w following max_w that reduces this function to the exact
+    # velocity form it replaced, frozen branch included - asserted by an
+    # exhaustive comparison against a transcription of the old law in
+    # test_control.py, not by inspection. Break either the gate or the bound
+    # below and that test is what tells you the equivalence went with it.
     if i_w is None:
         i_w = float(prev_w)
+    limit = tuning.max_w if tuning.integrator_max_w is None else tuning.integrator_max_w
 
     if abs(error) < tuning.deadband_w:
         reason = "deadband"
     else:
-        step_i = tuning.gain * error
-        # ⚠️ Freeze means "may not wind FURTHER", not "may not move". A strict
-        # freeze would strand the command at whatever it had reached until the
-        # inverter started tracking again - and the inverter is not tracking,
-        # that is what saturation means, so nothing would ever release it. The
-        # unwind direction is the escape route and stays open; the same rule is
-        # applied again to the output below.
-        if not frozen or abs(i_w + step_i) < abs(i_w):
-            i_w = i_w + step_i
+        moved = i_w + tuning.gain * error
+        # ⚠️ Freeze means "may not wind FURTHER in the direction it is already
+        # pushing". It may fall, cross zero, or reverse outright.
+        #
+        # It must NOT be encoded as "only corrections that shrink |i_w|": that
+        # is unsatisfiable for BOTH signs of error whenever the correction is
+        # larger than twice the integrator, i.e. every time the integrator is
+        # near zero. The loop then sits at its last value forever, because what
+        # clears the freeze is the inverter tracking again and not-tracking is
+        # the definition of saturation. Measured on that encoding: 0 W held
+        # indefinitely into a 2 kW import, where this form recovers next cycle.
+        #
+        # This is the same asymmetric rule the output freeze uses below, which
+        # has been in service on real hardware. It is applied here as well
+        # because the requirement is that the INTEGRATOR stop accumulating, not
+        # only the command.
+        #
+        # ⚠️ EXACTLY ZERO IS ITS OWN CASE, and it must be handled explicitly
+        # rather than falling into one of the two branches. "May not wind
+        # further in the direction it is already pushing" has no referent at
+        # zero: nothing is wound, and neither direction is "further". Writing
+        # this as `if i_w > 0 ... else ...` silently files zero under
+        # rising-only and permanently blocks the first push toward charging -
+        # the same deadlock as the shrink-only encoding above, mirrored in sign,
+        # and reachable because main.py resets i_w to exactly 0.0 on every stop
+        # and every reseed. Measured before the fix: 12 800 of 25 920 frozen
+        # ticks at i_w == 0.0 held the integrator, 8 304 of them changing the
+        # emitted command, worst case abandoning a 2 kW charge into a 4 kW
+        # export.
+        #
+        # Freezing at zero would also be pointless: the freeze exists to stop
+        # accumulation running away, and a first step from zero is bounded by
+        # the gain, the output clamp and the slew limit like any other.
+        if not frozen or i_w == 0.0:
+            i_w = moved
+        elif i_w > 0:
+            i_w = min(moved, i_w)
+        else:
+            i_w = max(moved, i_w)
 
-    # ⚠️ Applied EVERY cycle, frozen or not, and before the output clamp: the
-    # freeze is conditional, this bound is not. Order matters only in that the
-    # command below is derived from the already-bounded integrator, so no
-    # accumulated value can reach the wire even once.
-    i_w = max(-tuning.integrator_max_w, min(tuning.integrator_max_w, i_w))
+    # ⚠️ Applied EVERY cycle, frozen or not: the freeze is conditional, this
+    # bound is not. It is what makes the worst-case unwind time finite and
+    # knowable instead of a function of how long the error happened to stand.
+    bounded = max(-limit, min(limit, i_w))
+    if bounded != i_w:
+        # ⚠️ SAFETY-03 (alarm whenever the loop winds into a rail) must watch
+        # for THIS, not for "clamped" below. At the default limit == max_w the
+        # integrator bound is reached first and the command derived from it can
+        # then never exceed max_w, so "clamped" is unreachable on a default
+        # install - it survives only for a configuration that deliberately lets
+        # the integrator run above the rail. Two reasons rather than one
+        # because the two events want different alarms: "i-clamped" is the loop
+        # winding, "clamped" is a command that came out over the rating anyway.
+        reason = "i-clamped"
+    i_w = bounded
     want = i_w
 
     # ⚠️ Maintenance shaping (charge-only, cheap-window floor) used to live

goodwe_controller/app/main.py

@@ -39,7 +39,7 @@ from .control import Tuning, compute, maintenance_charge_floor, peak_at_risk
 from .hass import HomeAssistant
 from .maintenance import IDLE, MaintConfig, Maintenance
 from .mqtt import MqttPublisher
-from .p1 import P1Ingest, build_source
+from .p1 import P1Ingest, build_source, is_enabled
 from . import web
 
 OPTIONS_PATH = "/data/options.json"
@@ -71,7 +71,11 @@ class Controller:
             step_w=int(opts.get("step_w", 10)),
             saturation_w=float(opts.get("saturation_w", 500)),
             saturation_cycles=int(opts.get("saturation_cycles", 3)),
-            integrator_max_w=float(opts.get("integrator_max_w", 3000)),
+            # 0 / unset means "follow max_w", which is the recommended
+            # value. Read the note in control.py before raising it above
+            # max_w: every watt above the rail is unwind latency.
+            integrator_max_w=(float(opts["integrator_max_w"])
+                              if opts.get("integrator_max_w") else None),
         )
         self.maint = Maintenance(
             MaintConfig(
@@ -92,7 +96,7 @@ class Controller:
         # until it opts in.
         self.p1 = P1Ingest(phases=int(opts.get("meter_phases", 1)),
                            max_age_s=float(opts.get("meter_max_age_s", 30)))
-        self.p1_enabled = str(opts.get("meter_source", "off")) not in ("off", "")
+        self.p1_enabled = is_enabled(opts)
 
         # live state
         self.auto = bool(store.data.get("auto", opts.get("auto_start", False)))
@@ -320,16 +324,26 @@ class Controller:
             await asyncio.sleep(1)
 
     def publish(self) -> None:
-        self.mqtt.publish({
+        values = {
             "setpoint": self.target,
             "grid": self.grid,
             "battery": self.batt,
             "soc": self.soc,
             "phase": self.maint.phase,
             "status": "running" if self.auto else "stopped",
+        }
+        # ⚠️ ONLY when P1 ingestion is actually running. The ESP32's stale-input
+        # watchdog subscribes to sensor.p1_sample_age_s and forces the layer-1
+        # failsafe once it reaches max_age_s. With meter_source off there is no
+        # ingester feeding it, so published_age_s would be time-since-startup
+        # climbing without bound - i.e. every existing install would cross the
+        # threshold within 30 s and pin its inverter at 0 W forever. Publishing
+        # nothing leaves the entity non-existent, which is the status quo and
+        # what has_state() in the firmware is checking for.
+        if self.p1_enabled:
             # Recomputed here, once a second, on purpose - see P1Ingest.
-            "p1_age": round(self.p1.published_age_s, 1),
-        })
+            values["p1_age"] = round(self.p1.published_age_s, 1)
+        self.mqtt.publish(values)
 
     async def shutdown(self) -> None:
         """Deterministic wind-down. Do not skip this."""
@@ -497,6 +511,7 @@ async def amain() -> None:
                 broker.get("port", 1883) if broker else 1883,
                 broker.get("username") if broker else None,
                 broker.get("password") if broker else None,
+                omit=() if is_enabled(opts) else ("p1_age",),
             )
         except Exception as err:  # noqa: BLE001
             _LOG.warning("MQTT unavailable (%s) - continuing without status entities", err)

goodwe_controller/app/mqtt.py

@@ -60,7 +60,12 @@ AVAILABILITY = f"{BASE}/availability"
 
 
 class MqttPublisher:
-    def __init__(self, host, port, username=None, password=None):
+    def __init__(self, host, port, username=None, password=None, omit=()):
+        # `omit` drops sensor keys from discovery entirely. ⚠️ Announcing a
+        # sensor that nothing will ever publish to is not harmless here:
+        # p1_sample_age_s is a watchdog input, and an entity that exists but is
+        # never fed is a worse signal than one that does not exist at all.
+        self.omit = set(omit)
         self.enabled = mqtt is not None and bool(host)
         self.client = None
         if not self.enabled:
@@ -94,6 +99,8 @@ class MqttPublisher:
 
     def _announce(self) -> None:
         for key, object_id, name, unit, dev_class, state_class, icon in SENSORS:
+            if key in self.omit:
+                continue
             cfg = {
                 "name": name,
                 "object_id": object_id,

goodwe_controller/app/p1.py

@@ -213,8 +213,16 @@ class QuarterAverager:
     halves credited to the two blocks, never attributed wholly to either.
     """
 
-    def __init__(self, phases: int = 1):
+    def __init__(self, phases: int = 1, max_hold_s: float = 30.0):
         self.phases = phases
+        # ⚠️ How long one sample may be held forward before the series is
+        # treated as a gap rather than a plateau. Without this the meter can die
+        # while importing 5 kW, come back ten minutes later, and the hold-forward
+        # credits 5 kW x 600 s to the capacity-tariff accumulator - a fabricated
+        # peak, on a permanent record, from data that was never measured. Set
+        # from meter_max_age_s: the point past which the reading is not trusted
+        # for control is the point past which it must not be billed either.
+        self.max_hold_s = float(max_hold_s)
         self._block: int | None = None       # epoch seconds of the block start
         self._acc = 0.0                      # W*s of offtake in the open block
         self._pp_acc = [0.0] * phases
@@ -273,16 +281,22 @@ class QuarterAverager:
             return closed
 
         cursor = self._last_t
+        # Beyond this instant the held value stops being evidence of anything.
+        # The stretch from here to `t` is walked so the block boundaries are
+        # still crossed correctly, but nothing is accumulated and `_elapsed`
+        # does not grow - which is what makes a closed block, always divided by
+        # the full 900 s, actually get dragged down by the missing coverage.
+        hold_end = self._last_t + self.max_hold_s
         while True:
             end = self._block + QUARTER_S
             stop = min(t, end)
-            dt = stop - cursor
-            if dt > 0:
-                self._acc += max(self._last_net, 0.0) * dt
+            covered = max(0.0, min(stop, hold_end) - cursor)
+            if covered > 0:
+                self._acc += max(self._last_net, 0.0) * covered
                 if self._last_pp is not None:
                     for i, v in enumerate(self._last_pp[: self.phases]):
-                        self._pp_acc[i] += max(v, 0.0) * dt
-                self._elapsed += dt
+                        self._pp_acc[i] += max(v, 0.0) * covered
+                self._elapsed += covered
             cursor = stop
             if stop < end:
                 break
@@ -321,7 +335,9 @@ class P1Ingest:
     def __init__(self, phases: int = 1, max_age_s: float = 30.0):
         self.phases = phases
         self.max_age_s = float(max_age_s)
-        self.averager = QuarterAverager(phases)
+        # The same threshold governs control and billing: a reading too old to
+        # steer by is too old to bill by. See QuarterAverager.max_hold_s.
+        self.averager = QuarterAverager(phases, max_hold_s=self.max_age_s)
         self.blocks: list[QuarterBlock] = []
         self.samples = 0
         self.parse_errors = 0
@@ -477,9 +493,17 @@ class HaDsmrSource:
                     continue
                 payload = json.loads(msg.data)
                 if payload.get("id") == 2 and payload.get("type") == "result":
+                    # ⚠️ Prime the cache, but do NOT build a sample from it.
+                    # get_states returns whatever HA currently holds, which
+                    # after a Core restart is a RestoreEntity value of unknown
+                    # age. Stamping that with ingest_ts=now resets the age to
+                    # zero and reports a fresh meter that may have been dead for
+                    # an hour - a synthetic sample hiding the outage from the
+                    # watchdog that exists to catch it. The cache is what lets
+                    # the FIRST real state_changed build a complete sample; the
+                    # age stays honest until one arrives.
                     for obj in payload.get("result") or []:
                         self._absorb(obj.get("entity_id"), obj.get("state"))
-                    self._schedule()
                 elif payload.get("type") == "event":
                     data = (payload.get("event") or {}).get("data") or {}
                     if data.get("entity_id") not in self.ids:
@@ -647,6 +671,18 @@ class MqttP1Source:
 # --------------------------------------------------------------------------- #
 # selection
 # --------------------------------------------------------------------------- #
+def is_enabled(opts: dict) -> bool:
+    """Whether P1 ingestion is switched on at all.
+
+    ⚠️ One definition, because three places depend on it and they MUST agree:
+    where the grid reading comes from, whether the ingest task is started, and
+    whether sensor.p1_sample_age_s is announced over MQTT discovery. An age
+    sensor announced with no ingester behind it is a watchdog input nobody is
+    feeding, and the ESP32 trips on it.
+    """
+    return str(opts.get("meter_source", "off") or "off").strip() not in ("off", "")
+
+
 def build_source(opts: dict, ingest: P1Ingest, session, broker: dict | None):
     """Return the transport named by `meter_source`, or None if disabled.
 
@@ -654,7 +690,7 @@ def build_source(opts: dict, ingest: P1Ingest, session, broker: dict | None):
     changing transport is a config edit, never a code path.
     """
     source = str(opts.get("meter_source", "off") or "off").strip()
-    if source in ("off", ""):
+    if not is_enabled(opts):
         return None
     if source == SOURCE_HA:
         return HaDsmrSource(session, ingest, {

goodwe_controller/config.yaml

@@ -65,7 +65,7 @@ options:
   step_w: 10
   saturation_w: 500
   saturation_cycles: 3
-  integrator_max_w: 3000
+  integrator_max_w: 0
   heartbeat_s: 10
   stale_input_s: 15
   auto_start: false
@@ -121,7 +121,7 @@ schema:
   step_w: int(1,100)
   saturation_w: int(100,2000)
   saturation_cycles: int(1,10)
-  integrator_max_w: int(100,15000)
+  integrator_max_w: int(0,15000)
   heartbeat_s: int(2,25)
   stale_input_s: int(5,120)
   auto_start: bool

goodwe_controller/test_control.py

@@ -24,6 +24,63 @@ def check(name, cond):
         fails.append(name)
 
 
+# ---------------------------------------------------------------------------
+# COVERAGE AUDIT - measured, not executed. Read this before adding a mechanism.
+#
+# THE INVARIANT: every mechanism in compute() must be noticed by AT LEAST TWO
+# checks when it is deleted. If you add a mechanism to compute(), re-run the
+# audit and add it to the table. If a figure here drops, a check has started
+# passing for a reason other than the one it names.
+#
+# THE TECHNIQUE, because there is no script to run: replace one mechanism in
+# control.py with a no-op, run this file, count the failures, restore. That is
+# the converse of the usual mutation - not "does a wrong value fail?" but "does
+# anyone notice when the mechanism is GONE?". It is kept as a comment rather
+# than as tooling on purpose: the only cheap way to automate it is to key on
+# source lines, which goes stale silently, and a green audit that has quietly
+# stopped testing anything is precisely the failure this ticket exists to fix.
+# A comment cannot go stale-green, because it never claims to be running.
+#
+# Measured at 389d9ec. Numbers are the lead's independent reproduction.
+#
+#   mechanism in compute()                     checks that fail when deleted
+#   ------------------------------------------ -----------------------------
+#   integrator freeze (AC 3)                                               2
+#   integrator clamp (AC 1)                                                6
+#   integrator bound follows max_w                                         4
+#   output clamp                                                           3
+#   slew limit                                                             4
+#   output freeze                                                          2
+#   deadband                                                               5
+#   quantisation                                                           2
+#   saturation detector, `saturated_now = False`                          11
+#   saturation duration (AC 2), fires instantly                            2
+#   sat counter reset on a good cycle                                      6
+#   target_grid_w bias                                                     3
+#   i_w=None seeding from prev_w                                           6
+#
+# The detector figure is for the `saturated_now = False` form specifically;
+# disabling it further down as `frozen = False` is a weaker mutation and gives
+# 10. Reproduce the same form or the number will not match.
+#
+# ⚠️ IT HAS FOUND A DEAD MECHANISM TWICE, BOTH THE SAME WAY: a clamp standing in
+# for the mechanism under test. Deleting the integrator freeze once failed
+# NOTHING, because the fixtures sat at max_w 2000 and the integrator bound
+# truncated a wound value back to exactly 2000 - the assertion passed on the
+# clamp. The output clamp was masked the same way by the integrator bound.
+# Hence: A FIXTURE MUST SIT CLEAR OF EVERY RAIL IT IS NOT TESTING. Where a test
+# names one mechanism, make that mechanism the binding one (see TCLAMP and TF).
+#
+# ⚠️ RUN MUTATIONS WITH `python -B` AND CLEAR app/__pycache__. CPython
+# invalidates a .pyc on (source mtime in whole seconds, source size), so a
+# same-second rewrite that also preserves the file size reuses stale bytecode
+# and the suite reports on code you are no longer running. It under-reported one
+# mutation here as 2 where the true figure is 6. The error is one-directional -
+# stale bytecode can only under-report - so every figure above is a lower bound
+# at worst, and the two zeros ever recorded were both confirmed by fixing them
+# and watching the count rise, which a caching artefact cannot do.
+# ---------------------------------------------------------------------------
+
 print("control law")
 
 # Deadband: inside meter noise, hold exactly - do not drift.
@@ -41,13 +98,22 @@ check("proportional step (gain 0.6)", d.target_w == 300)
 d = compute(prev_w=0, grid_w=-500, actual_w=0, tuning=T)
 check("export drives charging", d.target_w == -300)
 
-# Clamp
-d = compute(prev_w=1900, grid_w=1000, actual_w=1900, tuning=Tuning(max_w=2000, slew_w=5000))
+# Clamp.
+# ⚠️ integrator_max_w is lifted clear of max_w so that the OUTPUT clamp is the
+# mechanism under test. Left at the default the integrator bound truncates
+# first, these two assertions pass on that alone, and deleting the output clamp
+# fails nothing - the same masking that hid the integrator freeze.
+TCLAMP = Tuning(max_w=2000, slew_w=5000, integrator_max_w=5000)
+d = compute(prev_w=1900, grid_w=1000, actual_w=1900, tuning=TCLAMP)
 check("clamped to max_w", d.target_w == 2000)
 
 # Slew: from 0 with a huge error, no more than slew_w in one cycle.
 d = compute(prev_w=0, grid_w=5000, actual_w=0, tuning=Tuning(max_w=5000, slew_w=1000))
 check("slew limits one cycle", d.target_w == 1000)
+d = compute(prev_w=-1900, grid_w=-1000, actual_w=-1900, tuning=TCLAMP)
+check("clamped to -max_w", d.target_w == -2000)
+d = compute(prev_w=0, grid_w=-5000, actual_w=0, tuning=Tuning(max_w=5000, slew_w=1000))
+check("slew limits one cycle, charging", d.target_w == -1000)
 
 # Saturation needs DURATION: one diverging cycle must NOT freeze.
 t = Tuning(saturation_w=500, saturation_cycles=3)
@@ -78,7 +144,7 @@ print("SAFETY-04: the integrator is bounded apart from the output")
 # The historical runaway, with its real numbers. A commercial controller on
 # this site, with the inverter switched OFF, wound ~130 W every 4 s past 10 kW
 # and reported 14 768 W while its output clamp sat at 5 kW. At gain 0.6 that
-# rate is a standing error of 130/0.6 ≈ 217 W that never resolves, because the
+# rate is a standing error of 130/0.6 = 217 W that never resolves, because the
 # inverter is not there to resolve it. 150 cycles is past the ~113 it took to
 # reach 14 768 W at that rate.
 RUNAWAY_ERROR = 130.0 / 0.6
@@ -86,12 +152,12 @@ RUNAWAY_CYCLES = 150
 HISTORICAL_W = 14768.0
 
 
-def runaway(tuning):
+def runaway(tuning, sign=1):
     """Inverter off: it reports 0 W forever, the error never clears."""
     prev, i_w, sat = 0.0, 0.0, 0
     worst_i, worst_cmd = 0.0, 0.0
     for _ in range(RUNAWAY_CYCLES):
-        d = compute(prev_w=prev, grid_w=RUNAWAY_ERROR, actual_w=0.0,
+        d = compute(prev_w=prev, grid_w=sign * RUNAWAY_ERROR, actual_w=0.0,
                     tuning=tuning, sat_count=sat, i_w=i_w)
         prev, i_w, sat = d.target_w, d.i_w, d.sat_count
         worst_i = max(worst_i, abs(i_w))
@@ -99,33 +165,113 @@ def runaway(tuning):
     return worst_i, worst_cmd
 
 
-TR = Tuning(max_w=2000, integrator_max_w=3000)
+TR = Tuning(max_w=2000)          # integrator_max_w unset => follows max_w
 wi, wc = runaway(TR)
-check(f"runaway: integrator plateaus at {wi:.0f} W (<= 3000)", wi <= TR.integrator_max_w)
+check(f"runaway: integrator plateaus at {wi:.0f} W (<= 2000)", wi <= TR.max_w)
 check(f"runaway: emitted command peaks at {wc:.0f} W (<= 2000)", wc <= TR.max_w)
 check("runaway: nowhere near the historical 14 768 W", wc < HISTORICAL_W / 4)
 
 # ...and with the saturation detector deliberately defeated, so that only the
-# clamp is holding. This is the AC that says the two mechanisms are
-# independent: kill one, the other still bounds it.
-TD = Tuning(max_w=2000, integrator_max_w=3000, saturation_w=1e9)
+# clamp is holding. Kill one mechanism, the other still bounds it.
+TD = Tuning(max_w=2000, saturation_w=1e9)
 wi, wc = runaway(TD)
-check(f"runaway with the detector defeated: integrator still <= 3000 ({wi:.0f} W)",
-      wi <= TD.integrator_max_w)
+check(f"runaway with the detector defeated: integrator still bounded ({wi:.0f} W)",
+      wi <= TD.max_w)
 check("runaway with the detector defeated: command still <= max_w", wc <= TD.max_w)
 
-# The bound is not max_w. If someone "simplifies" them into one key this fails.
-d = compute(prev_w=0, grid_w=6000, actual_w=0,
-            tuning=Tuning(max_w=2000, integrator_max_w=3000, slew_w=5000))
-check("integrator bound is separate from the output clamp",
-      d.i_w == 3000 and d.target_w == 2000)
+# The mirror: the same runaway driving the other way. An export that never
+# clears winds the integrator negative just as hard.
+wi, wc = runaway(Tuning(max_w=2000), sign=-1)
+check(f"runaway (export direction): integrator bounded at {wi:.0f} W", wi <= 2000)
+check("runaway (export direction): emitted command <= max_w", wc <= 2000)
 
-# Freeze = does not accumulate. Same input twice; the integrator must not move.
-TF = Tuning(saturation_w=500, saturation_cycles=3)
+# The bound is a separate quantity, and the useful direction is BELOW max_w:
+# there it binds first and caps unwind latency tighter than the rail does.
+d = compute(prev_w=0, grid_w=6000, actual_w=0,
+            tuning=Tuning(max_w=2000, integrator_max_w=1000, slew_w=5000))
+check("integrator bound binds independently of the output clamp",
+      d.i_w == 1000 and d.target_w == 1000)
+
+# Freeze = may not wind further in the direction it is already pushing.
+# ⚠️ max_w is raised WELL above the fixtures on purpose. At the default 2000
+# the integrator bound truncates a wound value back to exactly 2000 and
+# satisfies these assertions on its own, so deleting the freeze outright
+# failed nothing - the clamp was standing in for the mechanism under test.
+# Any fixture here must sit clear of every rail, or it tests the rail.
+TF = Tuning(saturation_w=500, saturation_cycles=3, max_w=5000)
 f1 = compute(prev_w=2000, grid_w=800, actual_w=0, tuning=TF, sat_count=3, i_w=2000.0)
-check("frozen: integration does not accumulate", f1.i_w == 2000.0 and f1.frozen)
+check("frozen: integration does not wind further", f1.i_w == 2000.0 and f1.frozen)
 f2 = compute(prev_w=2000, grid_w=-800, actual_w=0, tuning=TF, sat_count=3, i_w=2000.0)
 check("frozen: unwinding is still allowed", f2.i_w < 2000.0)
+# ...and the same two on the charging side. Every freeze rule in this file has
+# a mirror, because the one that did not is the defect that got through review.
+f3 = compute(prev_w=-2000, grid_w=-800, actual_w=0, tuning=TF, sat_count=3, i_w=-2000.0)
+check("frozen (charging): integration does not wind further", f3.i_w == -2000.0)
+f4 = compute(prev_w=-2000, grid_w=800, actual_w=0, tuning=TF, sat_count=3, i_w=-2000.0)
+check("frozen (charging): unwinding is still allowed", f4.i_w > -2000.0)
+
+# ⚠️ REGRESSION, and the reason the first cut of SAFETY-04 was rejected. A
+# freeze encoded as "only corrections that shrink |i_w|" is unsatisfiable for
+# BOTH signs of error whenever |correction| > 2*|i_w|, so near zero the loop
+# stops moving forever - the freeze cannot clear, because clearing it needs the
+# inverter to track and not-tracking is what saturation means. Measured on that
+# encoding: 0 W held into a 2 kW import for as long as the sim ran.
+z = compute(prev_w=0, grid_w=2000, actual_w=600, tuning=T, sat_count=3, i_w=0.0)
+check("frozen at i_w=0: a 2 kW import still moves the command",
+      z.frozen and z.target_w == 1000)
+# ...and the next cycle the inverter is inside saturation_w of the command, so
+# the freeze clears on its own. Deadlock would show up here as frozen=True.
+z2 = compute(prev_w=1000, grid_w=1000, actual_w=600, tuning=T,
+             sat_count=z.sat_count, i_w=z.i_w)
+check("frozen at i_w=0: the freeze then clears", not z2.frozen)
+# Same stranding on the other side: a small positive integrator against export.
+z3 = compute(prev_w=100, grid_w=-1000, actual_w=800, tuning=T, sat_count=3, i_w=100.0)
+check("frozen at i_w=+100: a 1 kW export still moves the command",
+      z3.frozen and z3.target_w < 0)
+z4 = compute(prev_w=-100, grid_w=1000, actual_w=-800, tuning=T, sat_count=3, i_w=-100.0)
+check("frozen at i_w=-100: a 1 kW import still moves the command",
+      z4.frozen and z4.target_w > 0)
+
+# ⚠️ EXACTLY ZERO, BOTH DIRECTIONS. This boundary has a history: the first cut
+# deadlocked here under import, and the fix for it deadlocked here under export
+# because `if i_w > 0 ... else ...` files 0.0 under rising-only. main.py resets
+# i_w to exactly 0.0 on every stop and every reseed, so it is a normal state,
+# not a corner.
+zi = compute(prev_w=0, grid_w=2000, actual_w=600, tuning=T, sat_count=3, i_w=0.0)
+check("frozen at i_w=0.0: an import push moves the integrator",
+      zi.frozen and zi.i_w > 0)
+ze = compute(prev_w=0, grid_w=-2000, actual_w=-600, tuning=T, sat_count=3, i_w=0.0)
+check("frozen at i_w=0.0: an export push moves the integrator",
+      ze.frozen and ze.i_w < 0)
+# The COMMAND still holds at 0 W in that second case, and that is release/1.0's
+# rule, not a leftover: at prev_w == 0 the output freeze forbids starting to
+# charge while saturated, because commanding 0 while the inverter reports
+# hundreds of watts means something else is driving the bus. Asserted so that
+# nobody "fixes" it by accident - the integrator moving is what this ticket
+# owns, the command rule belongs to the output freeze.
+check("frozen at i_w=0.0: the output freeze still blocks a charge from 0 W",
+      ze.target_w == 0.0)
+# Where prev_w is already charging the output freeze does NOT block, and there
+# the difference reaches the wire: held at 0.0 the integrator abandons the
+# charge mid-export.
+zc = compute(prev_w=-2000, grid_w=-4000, actual_w=-600, tuning=T, sat_count=3, i_w=0.0)
+check("frozen at i_w=0.0: a charge is not abandoned during heavy export",
+      zc.target_w == -2000.0)
+
+# The general property, rather than another handful of points: while frozen the
+# integrator may be held ONLY when the correction would push it further from
+# zero on the side it already sits. Any other hold is a deadlock.
+stuck = []
+for i0 in [x * 25.0 for x in range(-80, 81)]:
+    for g in [x * 100.0 for x in range(-40, 41)]:
+        err = g - T.target_grid_w
+        if abs(err) < T.deadband_w:
+            continue
+        dd = compute(prev_w=0.0, grid_w=g, actual_w=1500.0, tuning=T, sat_count=3, i_w=i0)
+        if dd.i_w == i0 and not ((i0 > 0 and err > 0) or (i0 < 0 and err < 0)):
+            stuck.append((i0, g))
+check(f"frozen integrator never deadlocks, over {161*81} states"
+      + (f" (e.g. {stuck[0]})" if stuck else ""), not stuck)
 
 # False-positive guard: a normal 2 kW load step must not trip the detector,
 # because the plant needs several cycles to catch up on every one of them.
@@ -137,6 +283,107 @@ for _ in range(12):
     froze = froze or d.frozen
 check("a normal 2 kW load step does not trip the saturation freeze", not froze)
 
+# The convergence sim below runs WITHOUT a carried integrator. This is the same
+# 2 kW step in the configuration that actually ships, where main.py carries it.
+prev, actual, sat, i_w = 0.0, 0.0, 0, 0.0
+carried = 0
+for _ in range(12):
+    d = compute(prev, 2000.0 - actual, actual, T, sat, i_w)
+    prev, sat, i_w = d.target_w, d.sat_count, d.i_w
+    actual = actual + 0.94 * (prev - actual)
+    carried += 1
+    if abs(2000.0 - actual) < T.deadband_w:
+        break
+check(f"carried integrator converges in {carried} cycles (<=6)", carried <= 6)
+check("carried integrator does not overshoot the load", actual <= 2000.0 + T.deadband_w)
+
+# ⚠️ REGRESSION: an integrator allowed to wind past the rail buys nothing (the
+# output clamp already bounds the wire) and costs extra cycles of
+# wrong-direction power after every saturation event. 4000 W load held to
+# saturation, then dropped to 0; the figure is the command on the first cycle
+# after the drop. This is what makes the DOCS advice checkable.
+def unwind(t):
+    prev, actual, sat, i_w, load = 0.0, 0.0, 0, 0.0, 4000.0
+    for c in range(16):
+        if c == 15:
+            load = 0.0
+        d = compute(prev, load - actual, actual, t, sat, i_w)
+        prev, sat, i_w = d.target_w, d.sat_count, d.i_w
+        actual = actual + 0.94 * (prev - actual)
+    return prev
+
+
+tight, loose = unwind(Tuning(max_w=2000)), unwind(Tuning(max_w=2000, integrator_max_w=3000))
+check(f"after saturation ends the command is {tight:.0f} W (<= 1000)", tight <= 1000)
+check(f"headroom above max_w makes that worse ({loose:.0f} W) - hence the default",
+      loose > tight)
+
+print("SAFETY-04: the i_w=None path is still release/1.0, exactly")
+
+
+def legacy(prev, grid, actual, t, sat_count):
+    """release/1.0's control law, transcribed. Do not 'improve' this."""
+    reason = "tracking"
+    sc = min(sat_count + 1, 10) if abs(prev - actual) > t.saturation_w else 0
+    frozen = sc >= t.saturation_cycles
+    error = grid - t.target_grid_w
+    if abs(error) < t.deadband_w:
+        want, reason = prev, "deadband"
+    else:
+        want = prev + t.gain * error
+    target = max(-t.max_w, min(t.max_w, want))
+    if target != want:
+        reason = "clamped"
+    slewed = max(prev - t.slew_w, min(prev + t.slew_w, target))
+    if slewed != target:
+        reason = "slew-limited"
+    target = slewed
+    if frozen:
+        target = min(target, prev) if prev > 0 else max(target, prev)
+        reason = "saturated-freeze"
+    step = max(1, int(t.step_w))
+    return float(round(target / step) * step), sc, frozen, reason
+
+
+# ⚠️ Compare EVERYTHING observable, not just the number. A previous version of
+# this sweep compared (target_w, sat_count) only and passed 3024 cases while
+# `reason` had silently lost a value - which is the kind of thing a sweep this
+# broad exists to catch. `frozen` and `reason` are both in the tuple now.
+#
+# The one deliberate rename: what release/1.0 called "clamped" is now
+# "i-clamped", because the truncation happens on the integrator before the
+# command is derived from it. Aliased here rather than papered over - if any
+# OTHER reason ever diverges, this check goes red.
+ALIAS = {"i-clamped": "clamped"}
+diffs = []
+seen = set()
+for tune in (Tuning(), Tuning(target_grid_w=-10.0), Tuning(max_w=5000, slew_w=5000)):
+    for prev in (-2000.0, -500.0, -100.0, 0.0, 100.0, 500.0, 2000.0):
+        for grid in (-6000.0, -1000.0, -500.0, -14.0, 0.0, 14.0, 500.0, 1000.0, 6000.0):
+            for actual in (-2000.0, 0.0, 600.0, 2000.0):
+                for sc in (0, 2, 3, 9):
+                    d = compute(prev, grid, actual, tune, sc)   # i_w defaults to None
+                    seen.add(d.reason)
+                    got = (d.target_w, d.sat_count, d.frozen,
+                           ALIAS.get(d.reason, d.reason))
+                    if got != legacy(prev, grid, actual, tune, sc):
+                        diffs.append((prev, grid, actual, sc, got,
+                                      legacy(prev, grid, actual, tune, sc)))
+check(f"i_w=None reproduces release/1.0 over {3*7*9*4*4} cases, reason included"
+      + (f" (first diff {diffs[0]})" if diffs else ""), not diffs)
+
+# ...and the rename is not a quiet deletion: the signal SAFETY-03 alarms on has
+# to actually occur in that sweep, or its hook is dead.
+check("the integrator clamp reports itself as 'i-clamped'", "i-clamped" in seen)
+
+# "clamped" stays reachable, but only where the integrator is deliberately
+# allowed above the rail - then BOTH fire and the output clamp, which describes
+# the value actually emitted, is the one reported.
+dc = compute(prev_w=0, grid_w=6000, actual_w=0,
+             tuning=Tuning(max_w=2000, integrator_max_w=3000, slew_w=5000))
+check("the output clamp still reports 'clamped' when it is the binding one",
+      dc.reason == "clamped" and dc.i_w == 3000 and dc.target_w == 2000)
+
 print("capacity tariff")
 check("no forecast means no cap", maintenance_charge_floor(2500, None, 3500) == 2500)
 check("headroom caps the charge", maintenance_charge_floor(2500, 2000, 3500) == 1500)

goodwe_controller/test_p1.py

@@ -229,6 +229,47 @@ before = a.partial_ws
 a.add(sample(1000.0, at=BASE + timedelta(seconds=5)))
 check("an out-of-order telegram is dropped, not integrated backwards",
       a.partial_ws == before and a.elapsed_s == 10.0)
+# ⚠️ The assertion above is NOT sufficient on its own, and that is the whole
+# lesson: deleting the guard still passes it, because the negative interval is
+# separately refused by the `covered > 0` test. What the guard actually prevents
+# is the REWIND - without it the held timestamp moves back to +5 s and the next
+# telegram re-integrates the 5..10 s window that was already counted. The damage
+# only becomes visible one sample later, so the test has to go one sample later.
+a.add(sample(1000.0, at=BASE + timedelta(seconds=20)))
+check("...and the held timestamp is not rewound, so the next telegram "
+      "cannot double-count", a.elapsed_s == 20.0 and a.partial_ws == 20000.0)
+
+# A duplicate telegram (identical timestamp) is the same rule.
+a = QuarterAverager(1)
+a.add(sample(1000.0, at=BASE))
+a.add(sample(1000.0, at=BASE + timedelta(seconds=10)))
+a.add(sample(4000.0, at=BASE + timedelta(seconds=10)))
+a.add(sample(1000.0, at=BASE + timedelta(seconds=20)))
+check("a duplicate timestamp neither re-integrates nor replaces the held value",
+      a.elapsed_s == 20.0 and a.partial_ws == 20000.0)
+
+# A gap must not be filled with the last held value. The meter dies at 5 kW and
+# returns ten minutes later; hold-forward would credit 5 kW x 600 s to the
+# capacity-tariff accumulator - a fabricated peak, on a permanent record, from
+# data nobody measured.
+a = QuarterAverager(1, max_hold_s=30.0)
+a.add(sample(5000.0, at=BASE))
+a.add(sample(5000.0, at=BASE + timedelta(seconds=600)))
+check("a 600 s gap is held for at most max_hold_s, not for the whole gap",
+      a.partial_ws == 5000.0 * 30.0)
+check("the unobserved stretch does not count as elapsed time", a.elapsed_s == 30.0)
+closed = a.add(sample(5000.0, at=BASE + timedelta(seconds=900)))
+check("the outage drags the billed quarter down instead of inventing a peak",
+      len(closed) == 1 and abs(closed[0].offtake_avg_w - 300000.0 / 900.0) < 1e-9)
+check("...nowhere near the 5000 W a hold-forward would have billed",
+      closed[0].offtake_avg_w < 400.0)
+
+# The cap must not disturb a normally-spaced stream.
+a = QuarterAverager(1, max_hold_s=30.0)
+for i in range(0, 121, 5):          # a healthy 5 s telegram cadence
+    a.add(sample(2000.0, at=BASE + timedelta(seconds=i)))
+check("a healthy 5 s cadence is untouched by the hold cap",
+      a.elapsed_s == 120.0 and abs(a.offtake_avg_w - 2000.0) < 1e-9)
 
 # --------------------------------------------------------------------------- #
 print("ingest timestamp, age and staleness")
@@ -482,9 +523,15 @@ async def _e2e():
 
 live, wire = asyncio.run(_e2e())
 check("the websocket handshake and subscription complete", live.samples >= 1)
-# Six state_changed events arrived (two per telegram). The debounce is what
-# makes that three consistent samples instead of six half-updated ones.
-check("three telegrams produce three samples, not six", live.samples == 3)
+# ⚠️ TWO, not three. get_states primes the cache but must NOT build a sample:
+# HA returns whatever it currently holds, which after a Core restart is a
+# RestoreEntity value of unknown age, and stamping that with ingest_ts=now
+# resets the age and reports a fresh meter that may have been dead for an hour.
+# Only the two real state_changed telegrams become samples. Four state_changed
+# events arrived (two per telegram); the debounce is what makes those two
+# consistent samples rather than four half-updated ones.
+check("connecting does not manufacture a sample from cached HA state",
+      live.samples == 2)
 check("the final export-dominant telegram nets negative",
       live.last.net_w == -800.0)
 check("the sample was built over the wire, tagged with its transport",
@@ -492,9 +539,102 @@ check("the sample was built over the wire, tagged with its transport",
 check("an entity we did not subscribe to is never cached",
       "sensor.something_else" not in wire.cache and len(wire.cache) == 1)
 check("a mid-stream unavailable is a parse error, not a sample",
-      live.parse_errors == 1 and live.samples == 3)
+      live.parse_errors == 1 and live.samples == 2)
 check("the last good reading survives the unavailable", live.net_w == -800.0)
-check("the averager integrated the live stream", live.averager.elapsed_s > 0.5)
+check("the averager integrated the live stream", live.averager.elapsed_s > 0.2)
+
+# The reason get_states still matters: it is what lets the FIRST real telegram
+# build a complete sample instead of waiting for every entity to change once.
+check("the primed cache let the first telegram build immediately",
+      live.samples == 2 and live.last.import_w == 0.0)
+
+# --------------------------------------------------------------------------- #
+print("the age sensor must not exist when P1 is off")
+# ⚠️ This is a fleet-wide regression guard, not a nicety. The ESP32 watchdog
+# does `id(p1_age_s).has_state() && id(p1_age_s).state >= max_age_s` and forces
+# the layer-1 failsafe. published_age_s counts from P1Ingest.__init__, so if the
+# age were published with meter_source off it would climb past 30 s on every
+# existing install within half a minute and pin the inverter at 0 W forever.
+
+from app.p1 import is_enabled          # noqa: E402
+from app.mqtt import SENSORS, MqttPublisher   # noqa: E402
+
+check("meter_source off is disabled", is_enabled({"meter_source": "off"}) is False)
+check("a missing meter_source is disabled", is_enabled({}) is False)
+check("an empty meter_source is disabled", is_enabled({"meter_source": ""}) is False)
+check("ha_dsmr is enabled", is_enabled({"meter_source": SOURCE_HA}) is True)
+check("mqtt_p1 is enabled", is_enabled({"meter_source": SOURCE_MQTT}) is True)
+
+# The entity id SAFETY-01's firmware subscribes to, pinned by object_id.
+row = [s for s in SENSORS if s[0] == "p1_age"]
+check("the age sensor is declared exactly once", len(row) == 1)
+check("its object_id pins entity_id to sensor.p1_sample_age_s",
+      row[0][1] == "p1_sample_age_s")
+check("it is published in seconds", row[0][3] == "s")
+
+
+class _RecordingClient:
+    def __init__(self):
+        self.sent = []
+
+    def publish(self, topic, payload=None, retain=False):
+        # Topic AND payload: object_id, the thing that actually pins the entity
+        # id, only appears in the discovery payload. Recording topics alone made
+        # the "is not announced" check pass for the wrong reason.
+        self.sent.append(f"{topic} {payload}")
+
+
+def _announced(omit):
+    pub = MqttPublisher(None, 1883, omit=omit)   # host None -> never connects
+    pub.client = _RecordingClient()
+    pub._announce()
+    return " ".join(pub.client.sent)
+
+
+check("with P1 off the age sensor is never announced",
+      "p1_sample_age_s" not in _announced(("p1_age",)))
+check("the other status entities are still announced with P1 off",
+      "goodwe_grid_power" in _announced(("p1_age",)))
+check("with P1 on the age sensor IS announced",
+      "p1_sample_age_s" in _announced(()))
+
+# And the publish dict itself, through the real Controller.
+from app.main import Controller            # noqa: E402
+
+
+class _Store:
+    data = {}
+
+    def set(self, *a):
+        pass
+
+    def get_time(self, *a):
+        return None
+
+
+class _Pub:
+    def __init__(self):
+        self.last = {}
+
+    def publish(self, values):
+        self.last = values
+
+    def close(self):
+        pass
+
+
+pub_off = _Pub()
+Controller({"meter_source": "off"}, None, _Store(), pub_off).publish()
+check("with P1 off, p1_age is absent from the published payload",
+      "p1_age" not in pub_off.last)
+check("...while the normal status keys are still published",
+      "setpoint" in pub_off.last and "grid" in pub_off.last)
+
+pub_on = _Pub()
+Controller({"meter_source": SOURCE_HA}, None, _Store(), pub_on).publish()
+check("with P1 on, p1_age is published", "p1_age" in pub_on.last)
+check("...as a number, so has_state() becomes true only once we feed it",
+      isinstance(pub_on.last["p1_age"], float))
 
 print()
 if fails: