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goodwe-addon/goodwe_controller/app/shadow.py
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UX-08 2c: short refusals, error texts and option texts
Validator refusals name the setting by its label and key, say what is
wrong and what to change, and keep the rejected value and limit. Option
names and descriptions are short in en and nl; citations moved to DOCS
"For installers" and the test_translations citation check now pins the
instruction on the tab and the record in DOCS. No rule, key, schema,
default or exit code changed. Allowlist 167 -> 43 (log lines only).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LyR88rXETvwhTgx6yHE39p
2026-09-27 05:55:45 +02:00

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"""SAFETY-10 - shadow mode: the whole decision path, and no command.
WHAT DEFECT THIS PREVENTS
=========================
Not one defect - the CLASS of them. Every optimiser fault this repository has
found was invisible from outside while it was happening, and each one was paid
for at the meter before anybody could see it:
* SAFETY-45 arbitrage against a binding `peak_cap_w` ran 28 charge onsets an
hour, the grid swinging -455 .. +3200 W, and put a billed
quarter 59 W over the cap;
* TARIFF-14 the price lookup answered for the wrong quarter-hour 45 minutes
in every 60, and traded on it;
* SAFETY-46 the SoC ceiling churns 598 Wh to gain 310 Wh, no hysteresis.
There was no way to WATCH what the optimiser would do without letting it do it.
A commissioning engineer could arm arbitrage and find out, or not arm it and
learn nothing. Shadow mode is the third option: strategies, arbiter, clamps and
guards all run, the decision is recorded with its reason, and NOTHING THE
CONTROLLER DECIDES REACHES THE INVERTER.
⚠️ AND OF THOSE THREE, A SHADOW RUN CAN SHOW YOU EXACTLY ONE - SEE THE NEXT
SECTION. This header used to name SAFETY-45's limit cycle as the example
of what shadow mode surfaces. That was false, and SAFETY-47 measured it.
⚠️ WHAT A SHADOW RUN CAN AND CANNOT SHOW (SAFETY-47)
=====================================================
SHADOW MODE CANNOT SURFACE A CLOSED-LOOP DEFECT. Not badly, not partially -
NOT AT ALL, and by the same construction that makes it safe. The actuator is
held at WIRE_W and the carried command is re-seeded to WIRE_W, so every
MEASURED input - the meter, the quarter accumulator behind it, the battery
power, the state of charge - describes a plant that DID NOT RESPOND. A
closed-loop defect is by definition one whose stimulus is the plant's response
to the controller. No response, no stimulus, no defect to see.
That is not a gap to be closed later. Feeding the guards a simulated plant
instead is what SAFETY-10 §4 refuses for the sign watchdogs, for a reason that
applies to all of this: a controller reacting to a plant that does not exist
drifts further from reality every tick, and three cycles in its numbers
describe nothing. THE CLOSED-LOOP ANSWER COMES FROM A CLOSED-LOOP RIG
(TEST-23 stage 3) OR FROM A LIVE RUN. There is no third place.
So, of the three defects above, measured on that rig at `peak_cap_w` 1500 /
house 1200 / `max_w` 2000, one hour at a 5 s cycle:
* SAFETY-45's limit cycle NOT VISIBLE. Live: 28 charge onsets, the grid
swinging -455.5 .. +3200.0 W, the guard engaged
on 410 of 720 cycles. Shadow, same hour, same
code: 1 onset, the grid flat at the 1200 W
house, the guard engaged on 0 of 720. Every
term of `wanted = batt_w + excess` is measured.
* SAFETY-46's SoC churn NOT VISIBLE. The SoC moves 0.000000000 pp in a
shadow run, because it is the pack's integral of
what the pack was commanded and the pack was
commanded 0 W. No SoC limit can be REACHED in a
shadow run; the ones already crossed when it
started are reported, and that is all.
* TARIFF-14's wrong quarter VISIBLE, and it is the one. The price lookup's
inputs are the CLOCK and the PRICE SERIES, and
neither is a function of what the battery did.
Measured: which hour the strategy picked, its
price and the spread it cleared are identical
live and shadow on 720 of 720 charging cycles,
AT A BINDING CAP.
⚠️ THE EXEMPTION THAT USED TO BE HERE WAS TRUE UNTIL SAFETY-45 MERGED. This
module, DOCS.md and DECISIONS/SAFETY-10-shadow-mode.md all said "the strategies
are unaffected - they ask for a fixed power from inputs that do not depend on
what the battery did". SAFETY-45 made the buy leg `min(asked, headroom)` with
headroom = (900 / remaining) x (ceiling - projected)
and `projected` reads the OPEN QUARTER'S ACCUMULATOR - the meter - which is a
function of what the battery did earlier in that same quarter. The strategy
became closed-loop the day that landed. What survives of the exemption, and
only this:
WHICH hour a strategy picks, and WHY, are unaffected.
HOW HARD it trades is not.
⚠️ AND THE SIZE A SHADOW RUN RECORDS IS THE RIGHT ANSWER TO A QUESTION NOBODY
ASKED. `900/remaining` is correct arithmetic for a meter that is genuinely
under the ceiling - and in shadow the meter genuinely IS under it, because the
battery is not charging. So the number is not a bug; it is an answer computed
for a plant that did not exist. Measured on the same rig, shipped code:
cap / house live commanded shadow recorded over
1500 / 1200 -302.4 W -2000.0 W 6.61x
3500 / 3000 -502.6 W -2000.0 W 3.98x
3500 / 2000 -1502.6 W -2000.0 W 1.33x
3500 / 1800 -1702.6 W -2000.0 W 1.17x
15000 / 350 -2000.0 W -2000.0 W 1.00x
The last row is the fixture SAFETY-10's own evidence was taken on, which is why
nothing reported this. `words()` carries the caveat rather than a re-computed
number, and `DECISIONS/SAFETY-47-what-a-shadow-run-can-show.md` §3 records the
three alternatives that were rejected and why.
⚠️ "REACHES NOTHING" IS NOT "WRITES NOTHING", AND THE DIFFERENCE IS THE WHOLE
SAFETY ARGUMENT
=======================================================================
The inverter holds its last command FOREVER - it has no meter timeout
(HANDOVER.md §6), and firmware/goodwe-master.yaml's header records what that
cost when a controller stopped refreshing: Illusmart went silent mid-command
and the inverter held +5000 W for 113 s. main.py's own header carries the same
measurement. So a shadow mode that
simply stopped writing would leave whatever was standing when it was switched
on standing for as long as it was left on. That is the exact failure this
repository keeps finding - LOOKS HEALTHY BUT IS INERT - with the status page
calmly reporting that nothing is being commanded.
So shadow mode does write, and it writes ONE number:
the actuator is held at WIRE_W (0.0 W), refreshed on the ordinary
heartbeat, by the ordinary single writer.
That is a DEFINED, SAFE actuator state, it is the same state the operator's
stop button reaches, and it honours the contract firmware/goodwe-master.yaml
§"CONTRACT CHANGE" imposes on us - HA must rewrite the setpoint every ~10 s or
the ESP32's 30 s stale-input watchdog cannot tell "steady" from "dead". Going
silent would put that board into a tripped-watchdog state for the whole shadow
run, which is an ALARM being used as a MODE: the operator who learns that
`wd_tripped` is normal during shadow runs is the operator who ignores it when
the add-on has actually died.
⚠️ AND IT IS NOT A SECOND WRITE PATH. SAFETY-28's rule is one actuator, one
writer. Shadow mode files no claim, owns no transport and calls nothing in
hass.py. It is a SUBSTITUTION inside `Controller._write_unit()` - the single
choke point every write in this add-on already goes through - in exactly the
form the three substitutions above it take (non-finite -> 0 W, unauthorised ->
0 W, clamped -> the rating). It is the LAST of them, so SAFETY-28's
authorisation gate and SAFETY-03's clamp still grade the number the decision
path actually produced, and a shadow run therefore records that the clamp WOULD
have engaged.
THE DEFAULT, AND WHY IT IS NOT A PLAIN `true` (§ the ticket's own warning)
==========================================================================
The card is titled "default-on". Taken literally - `shadow_mode: true` in
`config.yaml`'s `options:` block - it is the worst change in this repository's
history. Home Assistant's Supervisor composes an add-on's effective options as
`{**config.yaml defaults, **the stored user options}`, so a NEW key with a new
default reaches EVERY install on the next update, including the one regulating
a real battery in the author's house today. Literal default-on silently stops
an existing install from controlling, and the only symptom is a battery that
has stopped doing anything.
There is no mechanism in the add-on options system that lets one key default
differently for a new install and an existing one: `options:` IS the default,
and there is exactly one of it. So "default-on for new" has to be expressed as
a value the add-on RESOLVES, not as a constant the Supervisor merges.
Hence three values rather than two, defaulting to `auto`:
off never shadow. The controller commands the battery.
on always shadow, whatever the start/stop button says.
auto shadow WHILE CONTROL IS STOPPED; live once it is started.
`auto` is default-on for a new install and a no-op for an existing one, and it
is that without any persisted marker, any migration, and any guess:
* a FRESH install ships `auto_start: false` and has no stored `auto` key, so
it comes up stopped -> shadow. It observes a day of decisions before it is
ever allowed to command anything. That is the card's intent, delivered.
* an install that is CONTROLLING - `auto_start: true`, or the operator has
pressed *Start / stop control* and the store carries `auto: true` - is
started, so `auto` resolves to LIVE and its behaviour does not change by
one watt.
* an install that is STOPPED keeps its actuator at 0 W exactly as before -
the same number, from the same writer, on the same heartbeat - and gains
the recording. The only thing that changes for it is what the status page
and the action log SAY.
⚠️ AND `auto` MEANS THE START BUTTON LEAVES SHADOW MODE. That is deliberate:
under `auto` the button reads "Start / stop control" and pressing Start is the
operator saying "control the battery". An operator who wants the decisions
recorded WHILE the loop runs sets `shadow_mode: on` explicitly - that is the
configuration this card exists to make possible, and it is the one that cannot
be reached by accident.
⚠️ AN UNRECOGNISED VALUE RESOLVES TO SHADOW, NOT TO LIVE. `validate.py` refuses
it at startup so this is not meant to be reachable, but the fail-safe direction
for "the operator's intent is unreadable" is the one that does not move energy.
THE FAILSAFES, ONE BY ONE (the card asks for each to be decided and recorded)
============================================================================
| failsafe | in shadow mode |
|--------------------------------|-------------------------------------------|
| SAFETY-02/30 sign watchdogs | INERT, and by construction rather than by |
| (per-unit and site) | a special case. They grade |
| | `Inverter.standing_w()` - what this |
| | controller has standing on the wire - and |
| | shadow mode holds that at 0 W. A 0 W |
| | command cannot oppose a meter, so the |
| | detector never arms. ⚠️ THIS IS THE ONE |
| | THAT HAD TO BE GOT RIGHT: fed the SHADOW |
| | decision instead, every shadow run would |
| | latch a trip within `sign_disagree_s` - |
| | the decision opposes a meter that never |
| | saw it - and that latch SURVIVES INTO |
| | LIVE OPERATION and a restart. Shadow mode |
| | would manufacture the failsafe it is |
| | meant to help debug. |
| SAFETY-03 clamp | OBSERVES. It runs on the number the |
| | decision path produced, `clamp_last` is |
| | set and every engagement goes to the |
| | action log, because "it would have hit |
| | the rating" is part of what a shadow run |
| | is for. It changes no command: the value |
| | it narrows is replaced by 0 W below it. |
| SAFETY-28 write authorisation | OBSERVES, for the same reason and in the |
| | same place - above the substitution, so |
| | it still asks who chose the number. |
| SAFETY-18 meter freeze | OBSERVES, unchanged. It takes no action |
| | in live operation either; it grades the |
| | resolved intent against a meter that has |
| | stopped moving, and both halves are as |
| | true in shadow as out of it. |
| SAFETY-07/24/25 peak guard | OBSERVES, AND SEES ONLY THE HOUSE. It is |
| | level-triggered and unlatched and it files|
| | its claim as usual, so the recorded |
| | decision is the real one FOR THIS METER - |
| | but every term of `wanted = batt_w + |
| | excess` is measured, and in shadow mode |
| | the battery contributes nothing to either.|
| | ⚠️ SAFETY-47: this row used to claim |
| | SAFETY-45's limit cycle was visible from a|
| | shadow run. It is not - 410/720 engaged |
| | cycles live against 0/720 in shadow, on |
| | the same hour and the same code. |
| SAFETY-31 circulation | OBSERVES AND MAY LATCH, legitimately. Its |
| SAFETY-42 delivery | evidence is MEASURED power, not a |
| | command: packs pushing against each other |
| | while every one of them is told 0 W is a |
| | real fault and a latch is the right |
| | answer to it. |
| operator stop (`auto` False) | SUPPRESSED AS A CLAIM, ENFORCED AT THE |
| | WIRE. It is the one deliberate change. |
| | Its `P_SAFETY` 0 W claim out-ranks |
| | everything, so leaving it in would make |
| | the recorded decision "stopped" on every |
| | cycle - the shadow run would answer the |
| | wrong question. The actuator state is |
| | identical either way, and the wire |
| | substitution is STRICTLY STRONGER than |
| | the claim: a claim can be out-ranked, and |
| | this cannot. |
| inputs missing, non-finite, | UNCHANGED. All of them resolve to 0 W, |
| allocator refusal, arbiter | which is what the wire gets in shadow |
| contradiction | mode anyway, so they act redundantly and |
| | are recorded as they always were. |
⚠️ MAINTENANCE IS NOT IN THAT TABLE BECAUSE SHADOW MODE DOES NOT TOUCH IT. The
state machines are ticked on every cycle today whether control is started or
not, so a stopped install already runs them against a battery that does not
move. Shadow mode inherits that, unchanged and unimproved; it is a pre-existing
property of `auto_start: false` and it is recorded here rather than quietly
fixed under another card's name.
LEAVING SHADOW MODE
===================
`Controller.cycle()` re-seeds its carried command (`self.target` and each
`inv.target`) to WIRE_W at the END of every shadow cycle, AFTER every in-cycle
guard has read the decision. Two things follow, and both are safety properties:
* the loop's `prev_w` and its integrator track WHAT IS ACTUALLY STANDING ON
THE WIRE, so every shadow cycle answers "from where the plant really is,
what would this controller do NOW" - a true statement about the present,
rather than a simulation of a counterfactual plant that drifts further from
reality every tick;
* the exit is safe BY CONSTRUCTION. The carried command already equals the
standing command, so the first live cycle slews from 0 W like any other
cycle. Carrying the shadow decision instead would let the slew limiter
depart from a base that never existed - up to a full `slew_w` step onto a
battery sitting at zero.
The entry is safe for the ordinary reason: the substitution happens on the very
first write of the very first shadow cycle, and `last_write` was not 0 W, so
that write is issued rather than skipped as unchanged.
"""
from __future__ import annotations
from . import messages
# ⚠️ CFG-03's mirror. `test_defaults_pin.py` part 2 discovers every
# module-level name ending in OPTION_DEFAULTS and asserts each value
# reproduces config.yaml EXACTLY, so this table cannot drift from the shipped
# default. Nothing in the add-on may carry a literal fallback for a key a
# mirror answers for - part 3 scans for that - which is why `main.py` asks the
# functions below and never reads `shadow_mode` itself.
SHADOW_OPTION_DEFAULTS = {
"shadow_mode": "auto",
}
#: The three values `shadow_mode` may take, in the order config.yaml's schema
#: lists them. `validate.py` refuses anything else by name.
MODES = ("auto", "on", "off")
#: What stands on the wire while shadow mode is engaged. ⚠️ A NUMBER, NOT A
#: SILENCE - see this module's header. It is 0.0 W for the same reason every
#: other refusal in this add-on is 0.0 W: fail toward inaction, and keep
#: commanding it so the inverter cannot be left latched on anything else.
WIRE_W = 0.0
#: SAFETY-47. What the recorded watts mean when a MEASURED billed quarter sized
#: them.
#:
#: ⚠️ "UPPER BOUND" AND NOT "SMALLER", AND THE DIFFERENCE WAS MEASURED RATHER
#: THAN ARGUED. Charging only ADDS offtake, so a live meter's `projected` is
#: never below a shadow meter's and the headroom is never above it: the shadow
#: size is >= the live size, with EQUALITY at the start of every quarter, where
#: `900/remaining` is 1.0 and neither plant has moved. Measured pairwise over
#: 3600 charging cycles in five configurations - 0 cycles below, 730 exactly
#: equal. A sentence reading "smaller" would have been false on every one of
#: those 730.
#:
#: ⚠️ AND IT NAMES NO FACTOR. How far under the bound a live run lands is a
#: property of the site - 6.61x at a 1500 W cap under a 1200 W house, 1.00x at
#: a cap that does not bind - and a number invented for the row would be a
#: second helping of the defect this constant exists to disclose.
SIZED_FROM_METER = (
"⚠️ AND ITS SIZE CAME FROM THE BILLED-QUARTER METER, WHICH HAS ONLY THE "
"HOUSE IN IT WHILE THE BATTERY IS HELD AT 0 W. A live run sizes the same "
"trade against a meter the battery is moving, so this is an UPPER BOUND "
"and not a prediction; how far under it a live run lands is a closed-loop "
"question and a shadow run cannot answer it")
def mode(opts: dict) -> str:
"""The configured `shadow_mode`, normalised to one of `MODES`.
⚠️ AN UNRECOGNISED VALUE ANSWERS `"on"`, NOT `"auto"` AND NOT `"off"`.
`validate.py` refuses such a value at startup, so this branch is not meant
to be reachable at all; it exists because the fail-safe direction for "the
operator's intent cannot be read" is the one that does not move energy. A
typo that silently resolved to `off` would put a battery under a controller
whose configuration nobody could parse.
"""
raw = opts.get("shadow_mode", SHADOW_OPTION_DEFAULTS["shadow_mode"])
text = str("" if raw is None else raw).strip().lower()
if text in MODES:
return text
return "on"
def engaged(opts: dict, *, control_started: bool) -> bool:
"""Is the battery being left alone right now?
`control_started` is `Controller.auto` - the persisted start/stop state,
which a fresh install gets from `auto_start` and an operator moves with the
*Start / stop control* button. See the header on why `auto` reads it.
"""
m = mode(opts)
if m == "off":
return False
if m == "on":
return True
return not control_started
def why(opts: dict, *, control_started: bool) -> str:
"""Which rung decided, in the words an operator can act on.
⚠️ THE REASON, NOT ONLY THE VERDICT - MUTATION.md's masking rule. `on` and
`auto`-while-stopped produce the same boolean and want different operator
actions: one is turned off by editing an option, the other by pressing a
button. A surface that showed only "shadow" would make a mutation that
swapped the two rungs invisible.
"""
# ⚠️ THE LIVE SENTENCES SAY "NOT IN SHADOW MODE", NOT "THE BATTERY IS
# BEING CONTROLLED". The second is FALSE on a stopped install with
# `shadow_mode: off` - nothing is regulating there either - and a row that
# is false in one of the four live states is a row an operator learns to
# discount. What is true in every live state is that what this add-on
# decides reaches the inverter; whether control is RUNNING is the
# `Stopped` banner's question and it is answered there.
m = mode(opts)
if m == "off":
return ("off (shadow_mode: off) - NOT in shadow mode: what this "
"add-on decides DOES reach the inverter")
if m == "on":
return ("on (shadow_mode: on) - decisions are recorded and nothing "
"is commanded")
if control_started:
return ("off (shadow_mode: auto, control is started) - NOT in shadow "
"mode: what this add-on decides DOES reach the inverter")
return ("on (shadow_mode: auto, control is stopped) - decisions are "
"recorded and nothing is commanded")
def words(opts: dict, *, control_started: bool, would_w: float | None,
sized_from_meter: bool, reason: str = "") -> str:
"""The status page's `Shadow mode` row.
⚠️ THE ROW IS RENDERED IN EVERY STATE, INCLUDING `off`. A surface whose
ABSENCE is how you learn which mode you are in is a surface an operator
has to already know about; TARIFF-11's rule is that the rendered text is
what gets graded, so there has to be text in both states.
`would_w` is the decision the path reached this cycle - what a live
controller would have put on the wire GIVEN THIS METER AND A BATTERY AT
0 W - and `reason` is `Resolution.explain()`, the same sentence the `Why`
row carries. Together they are the whole of "what would it have done, and
why"; without them the row would say a shadow run happened and nothing
about what it found.
⚠️ `sized_from_meter` HAS NO DEFAULT, AND THAT IS SAFETY-47's WHOLE POINT.
It is True when a MEASURED billed-quarter headroom sized the number being
recorded - `arbitrage.sized_from_meter()` answers it, and it is the one
place the question is asked. A default of False here would be a caller
that forgot the caveat rendering a row that reads exactly like a caller
that decided it did not apply, which is the shape of defect this card is
about. TEST-14's rule with a new name on it.
⚠️ AND THE PHRASE IS "ON THIS CYCLE", UNCONDITIONALLY, NOT ONLY WHEN THE
CAVEAT FIRES. Every number a shadow run records was reached from a plant
that did not respond; "WOULD HAVE COMMANDED -2 000 W" reads as a forecast
of a live run and no number here is one. The ⚠️ below is the STRONGER,
conditional statement about the cycles where the answer can be multiples
out - see this module's header for the measured table.
⚠️ AND IT IS NOT KEYED ON WHETHER THE TRADE WAS CAPPED. `arbitrage`'s own
sentence says "SIZED BY THE CAPACITY-TARIFF GUARD" only when the headroom
came out BELOW the ask - which in a shadow run is the START of the
quarter, where the two runs still agree. By the end of the quarter
`900/remaining` has multiplied the headroom past the ask, the trade is
NOT capped, the sentence is silent and the recorded number is at its most
wrong. A caveat keyed on that sentence would be quietest exactly where it
is needed loudest. `test_arbitrage.py` part 3d-8 drives that.
"""
head = why(opts, control_started=control_started)
if not engaged(opts, control_started=control_started):
return head
if would_w is None:
return (f"{head}; no decision has been reached yet - the inverter is "
f"held at {WIRE_W:.0f} W")
# ⚠️ THE THOUSANDS SEPARATOR IS SWAPPED ON THE NUMBER ALONE. Applied to
# the whole sentence it ate the comma out of `head` - and `head` is the
# half that says WHICH RUNG decided, which is the claim MUTATION.md's
# masking rule says must survive.
num = f"{float(would_w):+,.0f}".replace(",", " ")
out = (f"{head}; ON THIS CYCLE WOULD HAVE COMMANDED {num} W, inverter "
f"held at {WIRE_W:.0f} W")
if sized_from_meter:
out += f" {SIZED_FROM_METER}"
if reason:
out += f" - {reason}"
return out
def log_line(*, would_w: float, reason: str, sized_from_meter: bool) -> str:
"""The action-log line for one change of shadow decision.
⚠️ IT IS A FUNCTION FOR THE REASON `words()` IS ONE, AND SAFETY-47 LEARNED
IT THE EXPENSIVE WAY. This sentence used to be an f-string inside
`Controller._shadow_settle()`. Deleting the caveat from it there left all
29 files GREEN - the only check that could see the line drove a fixture
with `meter_source: off`, where no arbitrage decision and therefore no
caveat can ever be reached. A sentence assembled at a call site is a
sentence no check can grade, and the page would have said one thing while
the record a later analysis reads said another.
⚠️ AND IT IS THE SAME `SIZED_FROM_METER` CONSTANT THE ROW CARRIES, not a
second wording of it. Two sentences meaning one thing is how the two
surfaces start disagreeing about which cycles are caveated.
"""
out = (f"SHADOW: would have commanded {float(would_w):+.0f} W ON THIS "
f"CYCLE - {reason}")
if sized_from_meter:
out += f" {SIZED_FROM_METER}"
return out
def banner(opts: dict, *, control_started: bool, latched: tuple = ()) -> tuple:
"""`(level, text)` for the top of the status page, or `None` when live.
⚠️ IT GOES RED FOR A STANDING LATCH. The shadow banner sits ABOVE every
other branch of the cascade, because "the battery is not controlled" is
the one sentence that may never be displaced - but a failsafe latch that
is up while the controller is inert is up when it stops being inert. So the
banner says a safety stop outlasts shadow mode, and each latch keeps its
own red row below, which names it and says how it clears. The words are
`messages.banner_shadow()`'s (UX-09); `latched` names them for callers.
"""
if not engaged(opts, control_started=control_started):
return None
return ("bad" if latched else "warn", messages.banner_shadow(bool(latched)))
def problems(opts: dict) -> list:
"""`validate.py`'s rule: `shadow_mode` must be one of the three values.
⚠️ THE SENTENCE SPELLS `shadow_mode`. `configui.problems_by_field()` files
a refusal under the field whose key its text contains; a rule that never
names a key lands in the page's top-level block instead, where the operator
cannot see which control is wrong. UX-02's whole point is that the shipped
validator is the only rule surface, so the rule has to be readable there.
⚠️ AND IT IS A REFUSAL RATHER THAN A COERCION. `mode()` resolves an
unreadable value to shadow, which is the safe direction but is also a
SILENT reinterpretation of what the operator wrote - and an install left in
shadow mode by a typo commands nothing at all, indefinitely.
"""
raw = opts.get("shadow_mode", SHADOW_OPTION_DEFAULTS["shadow_mode"])
text = str("" if raw is None else raw).strip().lower()
if text in MODES:
return []
return [f"{messages.setting('shadow_mode')} is {raw!r}. Choose "
+ ", ".join(f"'{m}'" for m in MODES[:-1])
+ f" or '{MODES[-1]}'."]