diff --git a/goodwe_controller/test_tariff24.py b/goodwe_controller/test_tariff24.py
index 4fccf6f..f5b74a4 100644
--- a/goodwe_controller/test_tariff24.py
+++ b/goodwe_controller/test_tariff24.py
@@ -13,8 +13,15 @@ the profile itself. DECISIONS/TARIFF-24-modes-need-the-tariff-task.md.
    Leftover solar and one Cheap hours.
 3. The same with a gap below the cycle cost.
 4. Home and the Batteries screen agree.
-5. Nothing else moved: modes off, the site trade on a static profile, and a
-   feed site start the same task as before.
+5. UX-55: with every battery Solar first Home no longer says "no prices have
+   arrived" on a static profile, and still does with no profile and no feed.
+6. Nothing else moved: modes off starts no task; the gate rows in part 1 keep
+   the arbitrage and feed cases as before.
+
+Mutations (MUTATION.md, purged copies, graded over this file): the gate
+reverted to `provider or arbitrage` fails 18 checks in parts 1 to 5; `True`
+fails the modes-off rows; `bool(opts.get(...))` fails the exact-true row;
+dropping the arbitrage term fails the arbitrage rows.
 """
 
 import ast
@@ -32,6 +39,7 @@ sys.path.insert(0, os.path.join(HERE, "tools"))
 logging.disable(logging.WARNING)
 
 import opt11p3_replay as rp                                    # noqa: E402
+from named_absence import first, nth, present                  # noqa: E402
 import app.main as m                                           # noqa: E402
 from app import homeview, modetrade, packmode                  # noqa: E402
 from app import price as _price, static_tariff as _st          # noqa: E402
@@ -101,8 +109,9 @@ def _guards_of(node, guards=()):
 
 _TREE = ast.parse(open(os.path.join(HERE, "app", "main.py"),
                        encoding="utf-8").read())
-_AMAIN = next(n for n in ast.walk(_TREE)
-              if isinstance(n, ast.AsyncFunctionDef) and n.name == "amain")
+_AMAIN = first((n for n in ast.walk(_TREE)
+                if isinstance(n, ast.AsyncFunctionDef) and n.name == "amain"),
+               "amain() in main.py")
 _TASK_GUARDS = [g for g, n in _guards_of(_AMAIN) if n == "run_tariff_refresh"]
 
 
@@ -252,13 +261,16 @@ def charging_b(rows):
 
 
 def why_of(c, name):
-    return next(b["why_key"] for b in c.battery_cards if b["name"] == name)
+    card = first((b for b in c.battery_cards if b["name"] == name),
+                 f"a card for {name}")
+    return card["why_key"]
 
 
 # --------------------------------------------------------------------------- #
 print("\n2. end to end, night, modes on, static day/night, no feed, no arbitrage")
 c1, r1, started1 = drive(opts())
-_last = r1[-1]
+_last = nth(r1, -1, "the last cycle")
+_first1 = nth(r1, 0, "the first cycle")
 print(f"    tariff task started by amain's guard: {started1}")
 print(f"    tariff_plan: {None if c1.tariff_plan is None else c1.tariff_plan.words}")
 print(f"    mode_runs: {_last['runs']}")
@@ -266,41 +278,44 @@ print(f"    mode_tick reason / roles: "
       f"{None if _last['tick'] is None else (_last['tick'].why, dict(_last['tick'].roles))}")
 print(f"    Batteries screen why_key: A {why_of(c1, A)}, B {why_of(c1, B)}")
 print(f"    cycles with B charging: {len(charging_b(r1))} of {len(r1)}, "
-      f"B soc {r1[0]['soc']['b']:.1f} -> {r1[-1]['soc']['b']:.1f}")
+      f"B soc {_first1['soc']['b']:.1f} -> {_last['soc']['b']:.1f}")
 check("the tariff refresh task is started", started1)
 check("...and it adds no network call: with price_provider off the feed "
       "loader is never reached (it is replaced by one that fails)",
       not FETCHES and not _price.provider_configured(opts()))
-check("a fresh tariff plan with prices is held", _last["plan"] is not None
-      and _last["plan"].has_prices)
+check("a fresh tariff plan with prices is held", present(_last)
+      and _last["plan"] is not None and _last["plan"].has_prices)
 check("the price runs exist (mode_runs is not None) and carry a cheap run "
       "that holds in the night period",
-      _last["runs"] is not None and _last["runs"].on
+      present(_last) and _last["runs"] is not None and _last["runs"].on
       and _last["runs"].cheap is not None
       and _last["runs"].cheap.holds(_last["now"]))
 check("the Cheap hours battery charges from the grid in the night period",
       len(charging_b(r1)) > len(r1) // 2
-      and r1[-1]["soc"]["b"] > r1[0]["soc"]["b"] + 0.3)
+      and present(_last, _first1)
+      and _last["soc"]["b"] > _first1["soc"]["b"] + 0.3)
 check("...and the Leftover solar battery does not (no sun, no forecast)",
       not any(r["p"]["a"] < -200.0 for r in r1))
 check("...the reason is not 'no prices': neither battery reads no_prices",
       why_of(c1, A) != "no_prices" and why_of(c1, B) != "no_prices")
 check("...only the Cheap hours battery got the grid charge role",
-      r1[-1]["tick"] is not None
-      and r1[-1]["tick"].roles.get(B) == modetrade.CHARGE
-      and r1[-1]["tick"].roles.get(A) != modetrade.CHARGE)
+      present(_last) and _last["tick"] is not None
+      and _last["tick"].roles.get(B) == modetrade.CHARGE
+      and _last["tick"].roles.get(A) != modetrade.CHARGE)
 
 # --------------------------------------------------------------------------- #
 print("\n3. the same with a gap below the cycle cost")
 c3, r3, started3 = drive(opts(cost=0.20))
-_l3 = r3[-1]
+_l3 = nth(r3, -1, "the last cycle")
 print(f"    started {started3}; mode_runs {_l3['runs']}; "
       f"why A {why_of(c3, A)}, B {why_of(c3, B)}")
 check("the task is started and the plan is there, so mode_runs is not None",
-      started3 and _l3["plan"] is not None and _l3["runs"] is not None)
+      started3 and present(_l3) and _l3["plan"] is not None
+      and _l3["runs"] is not None)
 check("the reason is the gap: no_spread ('Prices differ too little'), "
       "never no_prices, on both batteries",
       why_of(c3, A) == "no_spread" and why_of(c3, B) == "no_spread"
+      and present(_l3) and _l3["runs"] is not None
       and not _l3["runs"].on)
 check("...and no battery charges from the grid",
       not charging_b(r3) and not any(r["p"]["a"] < -200.0 for r in r3))