OPT-34 round 3: the latch ends on time, with the run, with the mode, and with the night

- F1: an expired latch is dropped whatever the run state; plan_targets() and the
  store loader ignore one that has ended (no stale latch after a restart).
- F2: the "charge goes on" line only while a cheap run is on.
- F3: a battery that is off or no longer Leftover solar leaves the latch.
- F4: a run carries the latch on only if it starts by the bell start (06:00
  local) after the latch began (manager's call, 2026-10-31).
Tests: test_opt34 scenarios stale/stale_live and part 5; test_modes_p4 asks at a
moment inside the latch.

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

goodwe_controller/DECISIONS/OPT-34-the-night-charge-keeps-its-level.md

@@ -16,7 +16,16 @@ known, so the add-on does not depend on it.
    no-forecast gap does not refuse the next slice of the run (`weather_held()`,
    as TARIFF-24 does for the run under way). While a
    forecast is there the latch follows the plan, up or down as a fresh figure moves
-   it. It lasts through every cheap run on and one price slot after the last.
+   it. It lasts through every cheap run on and one price slot after the last, and it
+   ends at once when its end time passes, whatever the run state (it is also
+   ignored at a restart if it has ended). A battery that is switched off or
+   changed to another mode leaves it.
+   *Night bound (manager's call, 2026-10-31):* a run carries the latch on only if
+   it starts by the bell start (06:00 local) after the latch began; that run
+   finishes, plus one slot. Chosen over a fixed 12 h because the night tariff
+   (22:00-07:00) needs the 06:00-07:00 slice and 12 h from a late start would
+   reach into the day. With dynamic prices a chain of cheap slots cannot carry a
+   night's level into the next day.
 2. *The evening's tomorrow figure is today's until the bell starts*, 06:00 local
    (`BELL_FROM_H`, `solarfc._bell_start()`), not until midnight + 3 h.
    Nothing has been produced yet, so it is still the whole day.
@@ -37,7 +46,7 @@ plan, the screens and a restart also need the figure itself.
 06:00 and unchanged. After the figure ends, with a charge still going on: "No
 solar forecast now. The charge under way goes on to its planned level." /
 "Nu geen zonneprognose. De lopende lading gaat door tot het geplande niveau."
-(`home_words.solar.latched`, only while a latched battery is below its level).
+(`home_words.solar.latched`, only while a cheap run is on and a latched battery is below its level).
 
 **Not used.** A figure over 15 h old; a morning figure at night (12 h); a figure
 for another day; a bad value or unit; and no latch for a charge that has not
@@ -50,4 +59,4 @@ A fresh figure that LOWERS the level during a charge still lowers it, as before.
 **Mutants** (all red in `test_opt34.py`): no latch; window back to midnight + 3 h;
 15 h without a limit; no "usable at midnight" rule; the latch without the narrow
 gap, without its save, or not kept through the next run; the window 6 h after
-midnight instead of 06:00 local (DST); 15 h cut to 12 h; the new screen line off.
+midnight instead of 06:00 local (DST); 15 h cut to 12 h; the new screen line off or shown without a cheap run; no expiry check; no pruning of a changed mode; no night bound; a left-the-plan battery keeping its level.