PRICE-01: price_service provider, fallback chain, and the gate read from it

A new price source, `price_provider: price_service`: the owner's price server,
one fixed HTTPS host, a bearer token (new password option
`price_service_token`), wholesale energy only so markup and taxes are added as
for generic_dayahead.

The chain is server, then energy-charts, then the prices the history store
kept. A step counts only if it has a price for now. Each step down and back up
is one log line. With every source down a site plans from what it saved.

No price for now: one status row, one Home plan line and one notification, in
English and Dutch, cleared when a price returns. With this provider the
maintenance charge gate reads the provider's prices and keeps the Home
Assistant rule: the current 15-minute price is at or below today's average.

The token is hidden on the settings page, refused when missing, and taken out
of any error text. Other providers, `off` and the Home Assistant pair take the
road they always took (scripted-day probe against 0ce7d35: one line differs,
the refusal that lists the known providers). See
DECISIONS/PRICE-01-own-price-server.md.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/DECISIONS/PRICE-01-own-price-server.md

@@ -0,0 +1,95 @@
+# PRICE-01 - the owner's price server as the price source, with fallbacks
+
+**Status: for review.** Tests: `test_price_service.py`. One option added,
+`price_service_token` (password). Follows [[TARIFF-10]], whose section 4 this
+card answers for one provider. Design: the owner's price service note of
+2026-10-05. Owner go 2026-10-05 and 2026-10-14.
+
+## What it is
+
+`price_provider: price_service` reads `GET https://prices.kammenstraatha.duckdns.org/v1/dayahead/BE`
+with `Authorization: Bearer <token>`. The answer is the energy-charts layout
+plus `covers`, so the existing columnar parser reads it. The price is wholesale
+energy only; the framework adds markup and taxes, as for `generic_dayahead`.
+
+## Rules
+
+1. **The host is a constant in the plugin**, declared as its only egress host,
+   HTTPS only. The operator's `price_feed_url` is not read by this provider.
+   *Cost:* every client talks to the one host, and moving the server is a new
+   add-on version. *What replaces the per-site setting:* the egress allow-list,
+   TLS, and a token per client that the server can revoke.
+2. **The chain is server, then energy-charts, then the saved prices**
+   (`app/price_chain.py`). A step counts only if it has a price for *now*: a
+   server that answers with old prices is skipped like one that is down. A step
+   down and a step up are each one log line, written when the step changes. The
+   operator's `price_feed_url` is cleared for the energy-charts step, which is
+   asked for its own feed.
+3. **The saved prices are `/data/price_history.json`**, the file `PriceHistory`
+   already keeps (the last three Brussels days of what was published). They are
+   the all-in prices as stored; a change of markup shows from the next fetch
+   that works. A read from the store is not filed again.
+4. **No price for now** means no published price covers the present moment. Not
+   "none for the coming hours": before about 13:00 tomorrow's prices are not
+   published on any healthy day, and carried hours are already marked estimated.
+   It sets one status row (*Prices*), one Home plan line (English and Dutch),
+   and one notification (*No prices*, English and Dutch), taken down when a
+   price returns. A start-up before the first refresh finished is not a gap.
+   The notification is not re-asserted after a Home Assistant core restart
+   (SAFETY-34 does that for latched safety alarms); the status row stays.
+   *Open for the owner:* if "coming hours" should mean a look-ahead of N hours,
+   that is a change to `gate_for()` and `PriceWatch`, not to the chain.
+5. **The maintenance charge gate** (owner's decision, 2026-10-14): the charge may
+   run when the *current 15-minute price is at or below today's average*, today
+   being the Brussels day, computed from the provider's prices. This is the rule
+   the Home Assistant pair gave (`price_service.yaml`), so a site that moves from
+   the pair to the provider does not change when the maintenance charge runs.
+   It is not `TariffPlan.cheap_now()` (strictly below the mean of the firm
+   hours of the whole plan). This replaces, for this provider only,
+   TARIFF-10 section 4: its three reasons are answered as follows. (1) Two
+   writers: the pair beside a provider stays refused; `static_profile` beside
+   `price_service` is accepted and no longer writes `cheap`. (2) An expired or
+   absent plan shuts the gate (the charge waits), as an unavailable HA sensor
+   did. (3) The basis is the one above, not `cheap_now()`.
+6. **The token is a secret.** `password?` in the schema; hidden on the settings
+   page (`uilayout.HIDDEN`), which can keep `price_service` but not choose it;
+   never put in a message by the plugin; taken out of any reason text by
+   `price.scrub()`; the real transport reports only a status or an exception's
+   name. validate.py refuses `price_service` with no token, and a token with a
+   space or line break.
+
+## Where the gate equals the Home Assistant pair, and where it does not
+
+Equal: `test_price_service.py` section 8 feeds the same day both ways, to the
+rules in `price_service.yaml` (price at the quarter, average of today's
+quarters rounded to 0.00001 EUR/kWh, `<=`), over 6 days including both
+clock-change days, at three instants in every period, and through a real
+`Controller` for a whole day. Every answer is the same.
+
+Not equal, by design or by arithmetic:
+
+- The comparison is made on all-in prices. With a flat taxes figure and a
+  markup and taxes of at most five decimals the offset cancels and the answer
+  is the same. With `price_taxes_profile` (an hour-varying levy) the all-in
+  prices differ by hour, so the answer can differ from the wholesale comparison
+  the HA sensors made. A site on that profile should check before moving.
+- A quarter within 0.00001 EUR/kWh of the average can differ if markup or taxes
+  have more than five decimals.
+- The plan is retired when no refresh has succeeded for 90 minutes
+  (`TARIFF_MAX_AGE_S`) and the gate shuts then. How long the HA pair kept an
+  answer after its REST sensor stopped updating was not measured here.
+- The average is over the firm prices the provider holds for today. After a
+  restart in the middle of a day with only the saved part of today, it is the
+  average of that part.
+
+## Not covered
+
+- **No real answer of the server was seen.** No token was available. The
+  layout is the design's; `test_price_service.py` uses a mock and, for the
+  parser, the real energy-charts capture reshaped with the design's extra keys.
+  The first capture from the live server (rig test) should replace the mock.
+- The 429 limit (about 60 calls an hour) is not approached: one fetch per
+  30 minutes, and at most two requests when the server fails.
+- Battery modes read the plan as for `generic_dayahead` and were not changed.
+- The `price_service` REST and template sensors in Home Assistant are not
+  touched; they stop being read when the pair is cleared.