Merge release/1.0 (TARIFF-10) into TARIFF-14

CI on PR #80 was NOT a test failure. The workflow's "grade the merge, not
the branch" step refused the PR because it does not apply, and said so
itself: "REFUSED: refs/pull/80/head does not merge into release/1.0.
NOTHING HAS BEEN TESTED. This is not a test failure - no test ran."
Conflicts were CHANGELOG.md and test_price.py; app/price.py auto-merged.

CONFLICTS RESOLVED

* CHANGELOG.md - both entries belong under ## Unreleased. TARIFF-10's
  table row and section come first because it landed first. No version
  number is picked here; PKG-06/07's note stands untouched.

* test_price.py - BOTH cards appended a section "13". Nothing is
  dropped: TARIFF-10's stays 13, this card's is renumbered 14, and
  TARIFF-10's temp-directory teardown stays at the end of the file. The
  two share no fixture, option dict or helper name.

WHAT TARIFF-10 CHANGES FOR THIS CARD - nothing in the reasoning, and the
check is recorded rather than asserted (decision note §7).

In app/price.py the two do not meet: TARIFF-10 added provider_id() and
provider_configured() beside price_option() and routed load_prices()
through them - the option-reading layer, touching nothing in _Series,
at(), covers(), window() or _cover_table(). The merged at() is
byte-identical to the one the mutations were driven against.

Behaviourally TARIFF-10 makes run_tariff_refresh() run with arbitrage
OFF, so a provider-configured site now has a standing plan - and
therefore a _Series - where before it had none. It does NOT add an at()
consumer to the 30 s tick: static_status() builds a STATIC plan (hourly,
immune), main.py calls only plan.words on the fetched plan, and
price_forecast.price_permits()/begin_phase() have no caller in main.py
at all. So TARIFF-10 neither creates nor closes any exposure this card
is about - it enlarges the defect's reach the moment such a site arms
trading, which strengthens the fix without changing it.

RE-GRADED ON THE MERGED TREE, not carried over

* all 29 test files green;
* all EIGHT mutations re-driven, purged before each run, each reverted
  with the fingerprint re-checked. Same verdicts and same red-check
  counts as before the merge: M1 (the shipped one-hour scan, +68 B) red
  on 24 named checks across both files; M3 (the ZERO-BYTE tail rule) red
  on 4; M2/M4/M6 on 1 each, M5 on 2, M7 on 16, M8 on 14.
* Clean app/price.py on the merged tree: 90d8ca31f7c0109d, 85953 B.
* None of TARIFF-10's 650 new lines of checks moves under any of the
  eight - they grade resolve_tariff()'s reachability from a
  configuration, not the lookup.

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

goodwe_controller/app/price.py

@@ -917,6 +917,47 @@ def price_option(opts: dict, key: str):
     return v
 
 
+def provider_id(opts: dict) -> str:
+    """The selected plugin id, normalised. `"off"` when none is selected.
+
+    ⚠️ ONE SPELLING OF THIS EXPRESSION, AND TARIFF-10 IS WHY IT IS A FUNCTION.
+    `str(price_option(opts, "price_provider") or "off").strip()` was written out
+    twice - in `load_prices()` below and in `static_tariff.resolve_tariff()` -
+    and main.py's startup gate would have been a third. "Is a provider
+    configured" is now a DECISION the add-on takes (it is what starts the
+    background refresh), and a decision spelled out at three call sites is three
+    places to disagree about whether `"  off  "` or `None` counts.
+    ⚠️ `validate.py` deliberately keeps its own reader: it validates the RAW
+    options blob, including one the Supervisor never saw, so it must not route
+    through `price_option()`'s defaults. Note what this does NOT do: it does not
+    decide
+    whether the id names a shipped plugin - `load_prices()` and validate.py's
+    rule 7 own that, and answering "unknown" here would turn a typo into
+    "no provider" instead of into a startup refusal.
+    """
+    return str(price_option(opts, "price_provider") or "off").strip()
+
+
+def provider_configured(opts: dict) -> bool:
+    """Has the operator selected a price feed at all? (TARIFF-10)
+
+    THE DEFECT THIS PREVENTS: the background tariff refresh used to start only
+    when `arbitrage_enabled` was on, which ships `false` - so a site with a
+    provider configured fetched NOTHING, ever. `/data/price_history.json` was
+    never created, the *Price history* status row read `empty` forever, and
+    TARIFF-09's short-horizon warning could not fire because no fetch happened
+    to warn about. Measured over a 40 h two-instance soak: zero feed requests
+    and `present: false` across all 802 samples on the shipped default, against
+    a resolved plan on the same feed with arbitrage armed.
+
+    ⚠️ THIS IS NOT A TRADING SWITCH AND MUST NEVER BECOME ONE. It answers
+    "fetch prices?"; `arbitrage.enabled()` answers "move energy on them?", and
+    §10.1's priority 3 is gated on the second alone. See
+    `main.tariff_refresh_wanted()` for the one place the two meet.
+    """
+    return provider_id(opts) not in ("", "off")
+
+
 def export_price_eur_kwh(opts: dict) -> float:
     """AC4 / §9.3: the injection price is a SEPARATE SCALAR, not a second series.
 
@@ -1667,8 +1708,8 @@ async def load_prices(opts: dict, since: datetime, until: datetime,
     site condition, it is a plugin trying to read the markup, and turning it
     into "no price data" would hide the exact defect trap 1 exists to catch.
     """
-    pid = str(price_option(opts, "price_provider") or "off").strip()
-    if pid in ("", "off"):
+    pid = provider_id(opts)
+    if not provider_configured(opts):
         return PriceRead.no_data(
             "no price provider configured (price_provider is 'off'); "
             "§11.4: static profile, plan provisional, no arbitrage")