feat(victron): switch solar/battery accounting to AC-referenced values

.claude/learnings.md

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+# Project Learnings & Gotchas
+
+Evidence grading is explicit throughout. **CONFIRMED** = a stack trace, a source read at the pinned
+`.HA_VERSION`, or a deterministic reproduction. **OBSERVED** = real data from a real run, but with a
+plausible alternative explanation still open. **UNPROVEN** = a hypothesis kept only so it is not
+re-litigated from scratch. Never promote an entry a grade without new evidence. See `CLAUDE.md` →
+"NEVER write an unconfirmed learning".
+
+## Active Patterns
+
+### Home Assistant
+- **W→kWh accumulation via trigger-based `template:` sensor** (CONFIRMED by every accumulator in
+  `packages/victron.yaml` passing CI): `- trigger: [platform: time_pattern, minutes: "/1"]`,
+  `state: "{{ (this.state | float(0)) + (power/60000) }}"`. `this.state` self-reference reads the
+  entity's PREVIOUS state (pre-write). Use this for anything derived from a power reading. Grid
+  import/export moved off it to `sensor: platform: integration` for **accuracy**, not because this
+  pattern failed — 1/min sampling is coarse when the source pushes every 1-2 s.
+- **Cross-tick baseline/counter-delta tracking**: use a DEDICATED sibling sensor with its own plain
+  `state:`, declared AFTER its consumer(s) in the same trigger block; consumers then read the
+  pre-this-tick value via `states('sensor.the_baseline')`. **Behaviour CONFIRMED** by the
+  counter-delta tests. **Mechanism ("sensors in one trigger pass render in declaration order")
+  UNPROVEN** — inferred from the observed values, not read out of HA source. If you reorder that
+  block, re-run those tests rather than trusting the explanation.
+- **`sensor: platform: integration`** (Riemann-sum/trapezoidal) for power→energy when the source
+  updates faster than 1/min. CONFIRMED at 2026.8.1
+  (`components/integration/sensor.py::async_added_to_hass`): it subscribes to **both**
+  `async_track_state_change_event` and `async_track_state_report_event`, so even a same-value
+  re-post drives it — unlike classic `template:` sensors (see Anti-Patterns). With no
+  `max_sub_interval` it has **no timer at all**: the next source event integrates the whole elapsed
+  gap as one trapezoid, `elapsed = new_state.last_updated - old_state.last_reported`. Gaps through
+  `unavailable` are NOT billed (`validate_states` can't parse the old value, so no area is added).
+  It also tolerates a source that doesn't exist yet at HA startup.
+- **Repointing an entity across a platform change** (mqtt→template, template→integration) while
+  preserving Energy Dashboard history: keep the exact same `unique_id`, then do a ONE-TIME MANUAL
+  entity-registry reclaim after deploy (delete the orphaned old-platform row, rename the new entity
+  onto the freed entity_id). CONFIRMED at 2026.8.1: the registry key is `platform + unique_id`
+  (`entity_platform.py::_async_derive_object_ids` — `default_entity_id:` only *suggests*, it loses a
+  collision and you get `_2`), and history follows the **entity_id string**
+  (`recorder/entity_registry.py::_async_entity_id_changed`). Do the rename within ~5 min of restart:
+  `statistics_meta.py::update_statistic_id` refuses when the target statistic_id already exists, so
+  the `_2` entity must not have compiled statistics of its own yet. Full runbook in
+  `plans/victron-ac-referenced-accounting.md`.
+- **Derive deploy/migration docs from the BRANCH DIFF, never from the live system.** The HA host
+  runs whatever was last pulled, so `ha-mcp` state and the entity registry describe the *old* world.
+  Caught this the hard way: a deploy runbook told the user to repoint six `utility_meter` helpers
+  that this branch had already deleted from `packages/victron.yaml` — they only still existed live
+  because the host had not pulled. `git log -S`/`git diff origin/master...HEAD` is the source of
+  truth for what a deploy will change; the live system is only useful for values to record
+  beforehand and for UI-only state (`.storage`: Energy Dashboard prefs, dashboards, helpers created
+  in the UI) that is not in the repo at all.
+- **Verifying HA-version-specific behaviour**: pull the actual source at the pinned `.HA_VERSION` —
+  `gh api repos/home-assistant/core/contents/<path>?ref=<tag>`. This is what CLAUDE.md's "HA version
+  gate" operationalises, and it is what turned three of the entries on this page from guesses into
+  facts. Docs were ambiguous or silent every time it mattered.
+
+### Test Harness
+- **Step the mocked clock with `fast_forward(timedelta(...))`, never `jump_to_next(hour=...)`,
+  unless the code under test is genuinely time-of-day dependent.** CONFIRMED in `time_machine.py`:
+  `jump_to_next` is forward-only (`if target_dt <= current_time: target_dt += timedelta(days=1)`),
+  so re-requesting an already-passed hour silently advances a **full day**. Anchoring every test to
+  `hour=10` cost one day per test — 20 calls in `test_victron.py`, ~11 days of travel, and every
+  `platform: integration` step integrating 86400 s. Check the package first (grep `sun.`, `now()`,
+  `today_at`, `hour`): `packages/victron.yaml` has none, so those 20 jumps were cargo cult from
+  `test_pergola.py`, where sun elevation makes them load-bearing. See
+  `plans/victron-test-clock-simplification.md`.
+- **`pytest-timeout` charges session-fixture setup to whichever test triggers it** unless
+  `timeout_func_only = true`. CONFIRMED by thread dump: `--timeout=90` killed a whole pytest
+  invocation inside `docker_manager.py:603 → subprocess.run` (`docker compose up`, 60-90 s) before a
+  single test ran, reported against `test_automation_disabled` which had not started. Set
+  `timeout_func_only = true` in `pyproject.toml`; bound setup hangs with a job-level
+  `timeout-minutes` instead.
+- **Per-file test isolation via a separate `pytest` step in the CI job**: `pytest tests/<file>.py -v`
+  as its own step, with `--ignore=tests/<file>.py` on the shared step. Each step is its own process,
+  so the harness's session-scoped `docker`/`home_assistant`/`time_machine` fixtures start fresh.
+  Established for `test_pergola.py` in `.github/workflows/ha_check.yaml`. **What it actually buys:**
+  a deterministic per-file clock and container. **What it does NOT buy: hang prevention** — that was
+  claimed once and disproved (see Anti-Patterns). Copy the pattern (including the Job Summary /
+  PR-comment / fail-check steps' handling of multiple step outcomes) when a file genuinely needs its
+  own instance.
+
+## Anti-Patterns & Failures
+
+### Home Assistant
+- **Re-posting the IDENTICAL value via `set_state()` to force a downstream recompute** — does not
+  propagate through a `template:` sensor chain. CONFIRMED at 2026.8.1
+  (`helpers/event.py`): `async_track_template_result` subscribes to `EVENT_STATE_CHANGED` only,
+  never `EVENT_STATE_REPORTED`. Fix: nudge the value by 1 unit. **Scope note:** this is specific to
+  classic `template:` sensors — `sensor: platform: integration` listens to *both* event types and
+  IS driven by a same-value re-post (see Active Patterns).
+- **`sensor: platform: integration` rejects `device_class`/`state_class` as config keys** —
+  `'device_class' is an invalid option for 'sensor.integration'`. CONFIRMED by a real config-check
+  failure. The platform applies its own.
+- **`sensor: platform: integration` keeps its running total in the entity's own Python memory**
+  (restored via `RestoreSensor`) — not by re-reading its own HA-visible state. A `set_state()` REST
+  override displays briefly, then the next integration step silently overwrites it using the OLD
+  internal value. **Cannot be reset via `set_state()`.** Tests need a before/after baseline delta.
+- **Custom `attributes:` on a trigger-based `template:` sensor, read back via
+  `this.attributes.get(...)` across ticks — status UNPROVEN, do not re-litigate.** It failed in CI,
+  3 round-trips went into source-tracing HA core PR #172847 as the culprit, and it was then blamed
+  on the harness instead — but neither the "HA is broken" nor the "harness is broken" side was ever
+  positively demonstrated. The repo uses dedicated sibling baseline sensors regardless, which is a
+  better pattern on its own merits. **Transferable lesson (this part IS proven, repeatedly, in this
+  repo): when a CI-only test fails, establish whether the harness is at fault before redesigning
+  production YAML.**
+
+### Test Harness
+- **Harness calls that can block forever — CONFIRMED by a pytest-timeout thread dump.**
+  `ha_integration_test_harness` v0.11.0 calls `requests.get/post/delete` with no `timeout=`, so an
+  HA container that accepts the TCP connection but never answers blocks the process forever (dump:
+  main thread in `socket.recv_into` inside `requests.get`, waiting on the HTTP status line).
+  **`assert_entity_state(timeout=5)` does NOT protect against this** — its timeout is checked
+  BETWEEN poll iterations and each iteration calls the unbounded `get_state()`, so the ceiling is
+  never reached. Every `timeout=` in this suite was decorative against a wedged container.
+  `jump_to_next()`/`fast_forward()` are unbounded too (`subprocess.run(["docker","exec",...])`), but
+  they only write `/shared_data/.faketime` and never poll — a hang "in a jump" would be a hung
+  `docker exec`, not clock arithmetic. **Fix (implemented):** `tests/conftest.py` wraps the
+  module-level `requests` helpers to `setdefault` a 30 s timeout; CI adds
+  `pytest-timeout --timeout=90 --timeout-method=thread` (with `timeout_func_only = true`) and a
+  job-level `timeout-minutes: 20`.
+- **`--timeout-method=thread` aborts the whole invocation**, not just the timed-out test: it dumps
+  every thread's stack, then kills the process. Correct while a hang is undiagnosed; switch to
+  `signal` (raises inside the test, run continues, main thread only) once it is understood.
+- **pytest test order here is NOT file-definition order.** `tests/conftest.py`'s
+  `pytest_collection_modifyitems` sorts by `(0 if "test_pergola" else 1, item.nodeid)` — alphabetical
+  by nodeid. Don't reason about "the test before/after this one" from source position.
+- **`tests/test_airflow.py` has real cross-test ordering dependencies on the clock.** CONFIRMED by
+  breaking it: the delayed binary sensors (`delay_on`/`delay_off` = 10 min, trigger-based, no
+  `homeassistant:start` trigger) sit at `unknown` after boot. conftest's `baseline_states` seeds
+  their inputs and fires their triggers, but the result only lands once the mocked clock crosses the
+  delay window. Removing the single clock advance in `_assert_recomputes_after_reload` broke **two
+  unrelated tests** that were silently piggybacking on it running earlier in nodeid order. Any test
+  asserting a definite on/off from a delayed sensor needs a `fast_forward` before it — check before
+  touching clock calls in that file.
+- **Chaining multiple `time_machine.jump_to_next()` calls within one test — OBSERVED, mechanism
+  DUBIOUS.** Diagnostic dumps showed the entity's `last_updated` pinned to the reset's own timestamp
+  instead of advancing on a second/third jump. The data is real, but the conclusion ("the harness
+  won't re-fire the trigger") predates the discovery that HA can wedge and that every HTTP read was
+  unbounded — a wedged container produces exactly this symptom. Practical rule stands (one clock
+  advance per test; seed "already progressed" state via `set_state()`), but do not treat the stated
+  cause as established.
+- **One narrower flake, never root-caused (UNPROVEN, recorded so it is not re-investigated blindly):**
+  one test failed deterministically (2/2 runs, unaffected by a 5s→20s timeout bump) apparently only
+  because of its position in the nodeid-sorted suite. Skipped with a documented
+  `@pytest.mark.skip(reason=...)`; the coverage gap is trivial passthrough logic covered indirectly
+  by siblings. Worth re-testing now that the HTTP calls are bounded — the same wedged-container
+  explanation may cover it.
+- **~~The CI hangs are caused by `jump_to_next(month=...)` year-jumps in the pergola fixtures~~ —
+  DISPROVED.** A docs-only commit hung with byte-identical test code. The *mechanism* is real
+  (`jump_to_next` advances a full year once the target month has passed; the pergola fixtures do
+  this 6× and run first, reaching ~2032 by test #30), and per-file isolation is worth keeping for
+  determinism — but it was never the cause of the hang. The actual cause is the unbounded
+  `requests.get` above. Standing status: `plans/ci-test-isolation.md` → "Correction".
+
+## Log
+
+### 2026-08-16 — Victron AC-referenced solar/battery accounting (PR #101)
+- **Task:** Rewrote `packages/victron.yaml` so Solar and Battery are AC-referenced, then spent the
+  rest of the session on the CI fallout.
+- **Learning:** Production YAML landed well (state-only baseline sensors, `platform: integration`
+  for grid, explicit conversion-loss diagnostics). The debugging around it produced **three
+  successive confident root-cause claims that were each wrong**, all in the same way: a plausible
+  mechanism fitted to a single confirming CI run. In order — custom `attributes:` being broken in
+  HA; dropping a `jump_to_next` alignment call causing a hang; pergola year-jumps causing the hang.
+  Two had to be deleted from this file as false positives. `CLAUDE.md` now forbids writing a
+  learning without confirmed evidence, and this file grades every entry.
+
+### 2026-08-16 (follow-up) — grid import/export accuracy
+- **Task:** Switched `victron_grid_energy_import`/`_export` from 1/min sampling to
+  `sensor: platform: integration`; added `recorder: purge_keep_days: 5`.
+- **Learning:** `platform: integration` has sharp edges not in the docs: rejects
+  `device_class`/`state_class`; keeps its total in entity memory (immune to `set_state()` resets);
+  has no timer without `max_sub_interval`, so it bills the entire gap since the last source event as
+  one trapezoid; and it listens to state *reports* as well as changes. `recorder: purge_keep_days`
+  does not touch the Energy Dashboard — that reads long-term statistics, a separate store retained
+  indefinitely.
+
+### 2026-08-16 (follow-up) — the hang, actually diagnosed
+- **Task:** Stopped theorising, instrumented instead.
+- **Learning:** `pytest-timeout --timeout=90 --timeout-method=thread` named the blocking line on the
+  first try: `requests.get` with no `timeout=`, parked in `socket.recv_into`. HA accepts the
+  connection and never answers; the HA-side reason is still unknown, but the test side is now
+  bounded by a `requests` wrapper in `tests/conftest.py`. Two follow-on regressions, both caught and
+  both instructive: pytest-timeout charges session-fixture setup to the first test (fixed with
+  `timeout_func_only`), and the airflow reload helper's clock jump was secretly supplying the delay
+  crossing that two other tests depended on. Also cut ~11 days of pointless mocked-clock travel out
+  of `test_victron.py` by replacing 20 `jump_to_next(hour=...)` calls with 11 `fast_forward` calls.