TARIFF-08: the day-ahead feed is read in the shape it actually publishes

`generic_dayahead` could not read one byte of `api.energy-charts.info`, and
never had been able to. `_points_from_json()` asks for `doc["data"]`, a list of
`{start, price_eur_mwh}` objects; that document does not exist. Fetched live on
2026-09-10 the feed returns COLUMNAR parallel arrays and no `data` key at all -
`unix_seconds` (96 UTC epoch seconds, 900 s apart), `price` (96 floats),
`unit: 'EUR / MWh'`. Driving the shipped parser against that body:
`SourceUnavailable: the feed carried no 'data' list`. It is the only shipped
provider whose endpoint anybody has reached, so dynamic pricing did not work.

AND §11.4 MADE IT SILENT, which is why it survived to release: a parse error
becomes no_data, becomes the static profile, becomes arbitrage off - the
CORRECT degradation, saying nothing about the cause. A site would have sat on
the fallback indefinitely.

AND THE SUITE COULD NOT SEE IT, because every fixture was built from the
parser's own assumption. test_price.py, test_price_history.py and
test_static_tariff.py each built `json.dumps({"data": [...]})`, a shape invented
here and published by nobody, so the checks graded the parser against the
parser's guess - a closed loop no coverage inside it could ever have escaped.
MUTATION.md habit 19 records it as the fourteenth instance of habit 4 and the
first where the fixture and the code under test shared a SHAPE, not a number.

WHAT CHANGED

* `_points_from_columnar_json()` - a SECOND function, not a sniff. A parser that
  decides which document it received is one that can decide wrong, and a
  wrong-but-parseable response then becomes a price. Feeding the row shape to
  `generic_dayahead` is now a graded no_data.
* Unequal arrays are refused in both directions, with the two lengths in the
  reason. `zip()` stops at the shorter list silently, and a truncated `price`
  array would have produced a real series missing the evening peak - traded on
  as complete, where no data at all switches arbitrage off.
* A unit that is not EUR/MWh is refused. The plugin converts with a fixed
  0.001, and `MAX_PLAUSIBLE_EUR_KWH` only bounds prices that are too LARGE.
* `unix_seconds` are read as UTC instants explicitly; §9.3's Brussels rendering
  stays in `assemble()` rather than being copied into the plugin, where a
  mutation could not tell it from a no-op (M4 proved exactly that on a first
  draft, and the line was removed rather than fenced).
* A published null is dropped and logged with a count; an all-null body is
  no_data named by this parser rather than by the boundary validator.

FIXTURES

Two unmodified response bodies under `scenarios/`, captured by hand on
2026-09-10: quarter-hourly (2026-09-10, 96 points at 900 s) and hourly
(2025-09-10, 24 at 3600 s - the same endpoint before Belgium's 15-minute MTU).
`energy-charts-be-price-captures.json` records the URL, retrieval time, unit,
licence-as-returned and a sha256 of each, and the replay RE-DERIVES the
checksums, so a fixture edited to make a check pass stops being a capture. Data
CC BY 4.0, Bundesnetzagentur | SMARD.de, via Energy-Charts (Fraunhofer ISE),
published without changes - the same BE-zone licence check DATA-02 established.

The surviving invented fixtures are renamed `synthetic_row_feed` at every call
site. `engie_dynamic`, `totalenergies_dynamic` and `eneco_eddy` are untouched
and have no capture: their URLs are unverified and withdrawing them is
TARIFF-07's open decision. Nothing should read their green checks as evidence
that those feeds parse.

MUTATIONS - 12, all red, no survivors. Purged tree, mounted `:ro`, `python3 -B`
(TEST-15). M1 drop the equal-length refusal; M2 make it one-sided; M3 drop the
unit check; M4 `assemble()` stops rendering at the Brussels offset; M5 read
`unix_seconds` as a naive local clock; M6 zero-fill a null instead of dropping
it; M7 drop the all-null refusal; M8 sniff for the row shape; M9 drop the
deprecated warning; M10 drop the dropped-nulls warning; M11 edit one price in
the committed capture; M12 point `generic_dayahead` back at the row parser -
red across all three price suites.

END TO END, LIVE, 2026-09-10: `resolve_tariff()` returns a `TariffPlan`,
`origin='provider'`, 96 quarter-hourly points, spacing [900] s, no decimation,
first point 2026-09-10T00:00:00+02:00 at 0.30608 EUR/kWh all-in. FCST-04's H1
fix was never theoretical. All 29 test files green.

STILL OPEN: `generic_dayahead` asks for no date range, so the default URL
returns one published day - a full 48 h horizon is reached only through §8.3's
carry-forward fill.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU

goodwe_controller/scenarios/energy-charts-be-price-2025-09-10-hourly.json

@@ -0,0 +1 @@
+{"license_info":"CC BY 4.0 (creativecommons.org/licenses/by/4.0) from Bundesnetzagentur | SMARD.de","unix_seconds":[1757455200,1757458800,1757462400,1757466000,1757469600,1757473200,1757476800,1757480400,1757484000,1757487600,1757491200,1757494800,1757498400,1757502000,1757505600,1757509200,1757512800,1757516400,1757520000,1757523600,1757527200,1757530800,1757534400,1757538000],"price":[73.0,61.31,64.32,62.49,67.0,64.48,94.52,149.26,132.43,91.61,84.8,79.61,69.23,66.75,68.91,69.31,80.29,66.91,105.2,161.05,116.73,84.2,64.1,42.41],"unit":"EUR / MWh","deprecated":false}

goodwe_controller/scenarios/energy-charts-be-price-2026-09-10-quarterhourly.json

@@ -0,0 +1 @@
+{"license_info":"CC BY 4.0 (creativecommons.org/licenses/by/4.0) from Bundesnetzagentur | SMARD.de","unix_seconds":[1788991200,1788992100,1788993000,1788993900,1788994800,1788995700,1788996600,1788997500,1788998400,1788999300,1789000200,1789001100,1789002000,1789002900,1789003800,1789004700,1789005600,1789006500,1789007400,1789008300,1789009200,1789010100,1789011000,1789011900,1789012800,1789013700,1789014600,1789015500,1789016400,1789017300,1789018200,1789019100,1789020000,1789020900,1789021800,1789022700,1789023600,1789024500,1789025400,1789026300,1789027200,1789028100,1789029000,1789029900,1789030800,1789031700,1789032600,1789033500,1789034400,1789035300,1789036200,1789037100,1789038000,1789038900,1789039800,1789040700,1789041600,1789042500,1789043400,1789044300,1789045200,1789046100,1789047000,1789047900,1789048800,1789049700,1789050600,1789051500,1789052400,1789053300,1789054200,1789055100,1789056000,1789056900,1789057800,1789058700,1789059600,1789060500,1789061400,1789062300,1789063200,1789064100,1789065000,1789065900,1789066800,1789067700,1789068600,1789069500,1789070400,1789071300,1789072200,1789073100,1789074000,1789074900,1789075800,1789076700],"price":[216.08,216.08,214.92,200.0,223.37,201.43,196.32,190.0,199.53,194.83,180.53,172.23,179.88,175.77,167.1,173.89,163.29,165.99,171.41,178.73,170.27,177.37,187.71,201.07,193.62,207.61,218.27,226.77,227.17,234.05,236.99,229.94,248.93,227.5,216.08,195.67,215.99,195.01,177.1,155.09,174.91,152.71,139.59,123.83,140.77,123.19,114.96,94.5,102.77,96.63,94.57,116.34,114.63,126.82,129.89,123.95,105.0,119.11,121.0,136.79,123.41,135.01,135.0,156.68,146.88,152.16,162.02,181.78,154.76,184.28,194.3,215.76,197.23,234.15,253.03,296.58,345.32,389.16,482.99,559.0,551.11,446.41,358.97,295.9,271.39,268.06,241.43,238.01,239.7,226.41,223.05,211.56,218.21,210.61,197.78,171.79],"unit":"EUR / MWh","deprecated":false}

goodwe_controller/scenarios/energy-charts-be-price-captures.json

@@ -0,0 +1,54 @@
+{
+ "card": "TARIFF-08",
+ "what": "UNMODIFIED response bodies from the public EPEX BE day-ahead feed, captured so the SHIPPED parser can be replayed against what the source really publishes",
+ "why": "every price fixture in the suite was built from a `{\"data\": [{\"start\": ..., \"price_eur_mwh\": ...}]}` document that this feed has never published. The suite therefore graded `_points_from_json` against its own assumption - a closed loop that could not notice the assumption was wrong - and §11.4 turned the resulting failure into a silent fall back to the static profile. A captured real body is what breaks that loop, so these files are bytes, not a reconstruction: nothing here is pretty-printed, re-keyed or trimmed.",
+ "source": "Energy-Charts API (Fraunhofer ISE), api.energy-charts.info",
+ "upstream": "Bundesnetzagentur | SMARD.de",
+ "licence": "CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)",
+ "licence_note": "the BE bidding zone is in the API's CC BY 4.0 list, so redistribution is permitted with attribution. DATA-02 established this against the API's own OpenAPI document before committing `epex-be-dayahead-2025-09-01_2026-09-01.json`; both bodies below carry the same `license_info` string, recorded per file and asserted by the replay test.",
+ "attribution": "Data licensed CC BY 4.0 by Bundesnetzagentur | SMARD.de, retrieved via the Energy-Charts API (Fraunhofer ISE), https://energy-charts.info. Published without changes.",
+ "retrieved_utc": "2026-09-10T06:35:00+00:00",
+ "retrieved_with": "curl, by hand; no code in `app/` fetches these",
+ "shape": "COLUMNAR: parallel `unix_seconds` (UTC epoch seconds) and `price` arrays, plus `unit`, `license_info` and `deprecated`. There is no `data` key and no per-point object.",
+ "replayed_by": "test_price.py section 2b",
+ "files": {
+  "energy-charts-be-price-2026-09-10-quarterhourly.json": {
+   "url": "https://api.energy-charts.info/price?bzn=BE",
+   "note": "the SHIPPED default URL of `generic_dayahead`, verbatim and with no parameters, so the replay drives the bytes the add-on's own request produces",
+   "covers_local_day": "2026-09-10 (Europe/Brussels)",
+   "granularity_s": 900,
+   "intervals": 96,
+   "bytes": 1877,
+   "sha256": "176309d0020ad208320797385ef68b6a98ac248218539416cddf6579dd060487",
+   "unit_as_returned": "EUR / MWh",
+   "licence_as_returned": "CC BY 4.0 (creativecommons.org/licenses/by/4.0) from Bundesnetzagentur | SMARD.de",
+   "deprecated_as_returned": false,
+   "top_level_keys": [
+    "deprecated",
+    "license_info",
+    "price",
+    "unit",
+    "unix_seconds"
+   ]
+  },
+  "energy-charts-be-price-2025-09-10-hourly.json": {
+   "url": "https://api.energy-charts.info/price?bzn=BE&start=2025-09-10&end=2025-09-10",
+   "note": "a day BEFORE Belgium's 15-minute MTU (2025-10-01), so the same endpoint answers HOURLY. Kept because the parser must not assume either spacing, and a fixture at only one granularity cannot grade that",
+   "covers_local_day": "2025-09-10 (Europe/Brussels)",
+   "granularity_s": 3600,
+   "intervals": 24,
+   "bytes": 572,
+   "sha256": "03fe41690810df224611f4016899f856457f67a3c12c7654da17b1331ff2eff4",
+   "unit_as_returned": "EUR / MWh",
+   "licence_as_returned": "CC BY 4.0 (creativecommons.org/licenses/by/4.0) from Bundesnetzagentur | SMARD.de",
+   "deprecated_as_returned": false,
+   "top_level_keys": [
+    "deprecated",
+    "license_info",
+    "price",
+    "unit",
+    "unix_seconds"
+   ]
+  }
+ }
+}