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goodwe-addon/goodwe_controller/DECISIONS/SAFETY-83-peak-over-drain.md
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SAFETY-86: peak guard outranks the maintenance hold
During a HOLD the holding battery gives what keeps the quarter at the peak
aim. N=1: the peak floor is refiled at P_MAINTENANCE, as for a drain
(SAFETY-83). N>=2: the hold's pin is raised to the floor minus what the
other live batteries may place, so they give first. A site stop still
decides alone. The hold ends on its clock even if the level dipped.
Below the aim nothing changes (rows identical).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-01 00:56:34 +02:00

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# SAFETY-83 - the peak guard outranks the maintenance drain at N=1
**Status: DECIDED 2026-09-29 (owner go, P1).** Follows SAFETY-78's "Not
changed" list. Tests: `test_safety83.py`.
**The defect.** At N=1 the drain is the site SET at `P_MAINTENANCE` (60). The
peak floor is a limit at `P_PEAK` (50), and clause 2 applies only limits at or
above the winner, so the floor was ignored and the house imported what the
drain left. A 5000 W house under a 2500 W limit and a 2000 W drain banked
3000 W quarters; on the owner's settings (limit 3500, drain 2500, margin 50) a
breach starts at about 5950 W.
**The fix.** While a drain owns the setpoint at N=1 and the peak floor asks
for more than the drain rate, `main.py` (`_peak_over_drain()`) refiles that
peak claim at `P_MAINTENANCE`. The arbiter then applies it: the target is the
floor, still inside the safety limits, and a safety SET (100) still parks
everything. Where the floor is at or below the drain rate nothing changes.
- The order in effect is now the same at N=1 and N=2: safety limits and the
SAFETY-73 refusal > peak guard (with the SAFETY-79 margin) > maintenance >
modes > trade > loop (`arbiter.py`, beside the priorities).
- The drain keeps counting: the battery discharges at least the drain rate on
every cycle, so the cycle is not reset or stalled; it only ends sooner.
- Below the drain rate the rest is still exported (owner, 2026-09-29).
- Identity: `tools/safety78_identity.py --diff` against 35cdffe changes only
cycles where the guard asked for more than the drain; after such an episode
the commands are identical again and only the log and the idle loop's
integrator differ. N=2 is unchanged.
**Not changed.**
- Between the drain rate and the peak aim, the house still imports what the
drain leaves (N=1 behaviour kept by the identity). At N=2 the loop covers it.
- A maintenance HOLD (0 W, 120 min, battery full) still outranked the peak
guard at N=1. Fixed by [[SAFETY-86]].