admin 958f5cd218 Merge pull request 'FCST-06: cannot-persist is one question, asked after the attempt' (#75) from FCST-06 into release/1.0
The module claimed 'a store that cannot persist records nothing' and enforced it against `not self.ok` only. A store with ok=True whose _save() fails - a full volume, a read-only remount - kept answering yesterday() from memory until the next restart, which is the silently-forgetting cache the docstring rejects, reached by the condition the rule did not name.

Reproduced against real volumes rather than a monkeypatch: /data bind-mounted read-only (EROFS) and a full tmpfs (ENOSPC), with a healthy-/data control asserted either side. Before: yesterday() returned a 24-point series while the disk held {}.

Fixed in the code, not the docstring - weakening the doc would have documented a cache that forgets without saying so as intended.

The design answer is the part worth keeping: 'can this store persist' CANNOT be answered before the attempt, because a directory that was writable a moment ago is not a write that completed, so os.access or a probe write is a third symptom test wearing a predicate's name. It is answered after, once: _save() -> bool, true only if the file now holds what memory holds. The `not self.ok` test in _remember() is GONE rather than joined by a second one, and a check asserts its absence from the source. This is the same shape as FCST-04's M4 and FCST-05's HIGH - a rule enforced on the conditions someone thought of - and it is the first of the three to be closed by removing a test rather than adding one.

What is undone is the MERGE, not the store: a volume that fills at 14:00 leaves the yesterday written at 13:30 still answering. The snapshot is a deepcopy - measured, a shallow copy let a store holding 12 persisted points answer 24.

Evidence: 29/29 green. Six mutations, no survivors, purged tree each run with the mutated line greped off disk. One of them exposed an instrument defect now recorded in MUTATION.md: it printed 1 FAIL when the true figure was 3, because an f-string operand called len(read.points) and .points on a no_data raises Absence by design, killing the harness mid-section. One check earlier and it would have read as a survivor. A mutation's red count is a lower bound until the run is seen to reach the end of its section.
2026-09-10 08:52:09 +02:00

GoodWe RS485 Controller — Home Assistant add-on repository

Replaces a GoodWe battery inverter's vendor controller with a local one: holds net grid exchange at zero by emulating the inverter's smart meter over RS485, and runs the monthly battery maintenance cycle the vendor box was doing.

repository.yaml            add-on repository metadata
goodwe_controller/         the add-on
  config.yaml              manifest + options schema (the per-site config form)
  app/                     the controller
    control.py             the control law — pure functions, no I/O
    maintenance.py         the monthly cycle state machine
    hass.py                Supervisor/Core API access
    store.py               persistent state in /data
    mqtt.py                optional status entities
    web.py                 ingress UI — routes only, status and configuration
    config_page.py         the configuration page's markup, style and script
    configui.py            its field model, built from the Supervisor's own
                           schema + translations — owns no key, label or rule
    selfconfig.py          reading and writing this add-on's own options,
                           with the validate-first / compare-and-swap gate
    main.py                orchestration, heartbeat, failsafe behaviour
  test_control.py          runnable checks — no framework needed
  test_maintenance.py      runnable checks — walks a full cycle in fake time
  DOCS.md                  the add-on's documentation tab
  MUTATION.md              how to run a mutation so the result means something
  tools/mutation_run.sh    the mutation harness - purges bytecode, then grades
  tools/supervisor_selfapi_probe.py  what the Supervisor really permits and
                           returns, run against its own release image
firmware/goodwe-master.yaml  ESPHome config for the T-CAN485
estop/rs485_log.py           optional RS485 e-stop / bus witness
docs/GoodWe-RS485-Field-Guide.pdf  the guide techs carry (10pp, A4)
docs/build_guide.py          its single source - rebuilds the HTML and PDF
FIELD-GUIDE.md             how to edit and rebuild the guide

Picking this up after a break? Read HANDOVER.md first — current state, what is known broken, and what to do next.

Install

Settings → Add-ons → Add-on store → ⋮ → Repositories → add

https://gittea.kammenstraatha.duckdns.org/admin/goodwe-addon

then install GoodWe RS485 Controller.

⚠️ The repository must be PUBLIC for this to work. Home Assistant clones it anonymously; against a private repo the store shows nothing and gives no useful error. If it must stay private, install locally instead: copy goodwe_controller/ into the machine's /addons/ folder, then ha store reload — it appears as a Local add-on.

⚠️ Bump version: in goodwe_controller/config.yaml for every change. Supervisor keys the built image by that version, so without a bump it silently reuses the old image and your fix appears not to work — on your bench and on every client's machine.

Requires Home Assistant OS or Supervised. Add-ons cannot be installed on HA Container or Core.

Read this first

The inverter holds its last command forever. It has no meter-timeout of its own — a controller that dies mid-command leaves the battery running until a human intervenes. Measured on real hardware: 5 kW of discharge held for 113 seconds after a controller went silent.

Three layers exist because of that, and only the third covers the Home Assistant machine itself dying:

  1. ESP32 watchdog — no fresh setpoint for ~30 s → command 0 W, and keep commanding it.
  2. Wind-down before firmware updates — 0 W written before the update starts.
  3. RS485 e-stop (optional) — writes 0 W after 30 s of total bus silence.

Sites sold without the e-stop must have the acknowledgement in FIELD-GUIDE.md §10 signed.

Development

The control law and the maintenance machine are pure Python with no Home Assistant imports, so they run anywhere:

cd goodwe_controller
python3 test_control.py
python3 test_maintenance.py

Both must pass before shipping any change. To prove a check bites - the way almost every claim in this repository was established - mutate the module and run tools/mutation_run.sh, which clears __pycache__ first. It is not optional: a same-size edit reverted inside one second leaves CPython reusing the old bytecode, and the run grades code that is not there. goodwe_controller/MUTATION.md has the mechanism, the measurement, and what the flags do not do. They are not unit-test theatre — each assertion corresponds to a rule whose absence produced an observed failure on real hardware, and the comments in control.py say which.

Compatibility

Check the serial number, not the model name. Characters 6-8 of the serial are the platform tag:

tag platform verdict
ESU EMU ESA BPS BPU EMJ IJL 105 — ES/EM/BP, AA55-era meter bus supported
SPB SPN 745 — SBP G2 (GW…-SBP-20) no
ESN ESC 745 — ES G2 (GW…-ES-20) no
ETU EHU BTU … 205/745/753 — ET/EH/BT hybrids no
SDT DST MSU NSU … PV-only inverters — no battery to control no

A "-20" or "G2" suffix means a different platform with a different meter protocol. The tags come from the goodwe library's PLATFORM_105_MODELS, which is also what Home Assistant's own integration uses to pick a protocol.

  • GoodWe ES / BP family inverters (AA55 / RS485 meter-bus generation)
  • The protocol is reverse-engineered. There is no vendor contract, and a firmware change on GoodWe's side could break every installation at once. Say so when you sell it.
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