feat(observation): separate physical load and unfiltered EV-SDL model without dispatch

docs/netplan-v4-separated-observation.md

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+# Separate physical load / EV-SDL observation (NO dispatch or training permission)
+
+## Implemented 2026-10-02
+
+- `NetzfahrplanV4Messsicht` recalculates independent physical-load, physical-storage,
+  unfiltered modelled allocation and SolarEdge-origin views from explicitly identified
+  raw snapshots. Quality failures in held virtual accounts do not veto otherwise
+  consistent physical inputs. Missing/stale physical inputs still invalidate their
+  respective view. No automatic relaxation of age/skew limits.
+- EV/SDL model: delta = physical - requestedEV - requestedSDL; distribute delta in
+  proportion to the absolute requested powers. The SDL component is obtained from
+  physical minus modelled EV to preserve numerical closure. This is an accounting
+  convention, NOT independently measured EV and SDL and NOT a verified response.
+- Command changes more recent than the oldest physical feedback are flagged. Unknown
+  change timestamps, tracking mismatch, aged/missing origins and idle unallocated
+  power remain explicit. There is no held-value filter and no forced convergence of
+  displayed power to the requested value. All proposals keep `canDispatch=false`.
+- Actual legacy filter outputs are displayed solely for comparison. They are not
+  reused as inputs of physical-load or unfiltered partition calculations. No changes
+  to the legacy filter, physical driver, EV/SDL setpoints, SOC integration or accounts.
+
+## New read-only origin finding
+
+Selected event 38921 writes legacy PV variable 20335 using:
+
+    a = 10 ** GetValue(41853) * GetValue(37975) + GetValue(21447)
+    if (a < 0) a = 0
+    SetValue(20335, a)
+
+Arithmetic statements were inspected without exposing arbitrary scripts/credentials.
+Verified saved configuration: variable 37975 parent 35514, register 40083; scale
+41853 parent 48996, register 40084; battery 21447 parent 30789. An independently
+updated 20335 is therefore not an independent PV reading and cannot certify all
+input timestamps. A second constrained arithmetic read confirmed the condition
+`if ($a < 0)`; this clamp applies to the legacy calculated PV value, not to the
+new signed terminal-power observation. Neither proves the full AC/DC boundary.
+
+The staged observer additionally records the ORIGINAL mantissa and exponent, not
+only their periodically rewritten derived PV result. The alternative candidate
+uses the scaled terminal power ONCE for this inverter (removing its derived-PV
+and battery terms). GoodWe AC/DC boundaries and full-site physical boundary are
+still unverified. This is not a definitive corrected house meter or live forecast.
+
+## Standalone installation / operational scope
+
+Stage on test host: `/srv/agent/netplan-v4-separated-observer-stage`.
+User invocation inside Symcon only:
+
+    require '/srv/agent/netplan-v4-separated-observer-stage/install.php';
+
+Creates only a NEW root category, three textual diagnostic variables, observe and
+stop scripts and a NEW 30-second timer. Reads 23 existing numeric variables twice;
+no Modbus polling requests, network calls, archive settings, existing module or
+control timer updates. Existing 21-channel raw collector continues untouched.
+
+New daily journals contain the selected numeric raw snapshot and derived views.
+A new immutable mapping/inventory reference binds the corrected user EV allocation
+161.44 kWh / 39 kW. Original collector metadata and its correction addendum remain
+unchanged. No rescaling or resetting of virtual SOC/energy accounts.
+
+Derived journal and LATEST/STATUS reports are 0644 WITHIN mode-0700 private stage
+and data directories, allowing the authorized agent to inspect these selected
+new outputs without repeated manual exports. No permissions on original journals,
+Symcon directories or unrelated data are changed. Quotas reuse 64 MiB/day, 512 MiB
+in total and 100 MiB disk reserve; exceeding them stops recording visibly and does
+not delete old data. No network transfer or cloud trainer is activated.
+
+## Validation and limitations
+
+40 pure view checks + 32 native-mock checks passed on PHP 8.3 CLI at test host.
+Regression: 36 raw-capture + 19 native-capture + 34 accounting checks passed with
+new additive `raw_power`/`scale` units. Total 161 isolated checks. Full relevant PHP
+source lint passed. Not a full PHPUnit run, Symcon kernel trial or hardware test.
+
+Tests cover opposite EV/SDL requests, held output, non-unique partition labelling,
+negative terminal power, scale/sentinel validity, old dependency timestamps, changed
+commands, missing source, no duplicate native objects, unchanged existing signals,
+append preservation, source drift, private output restrictions and stop behavior.
+
+The observer is PREPARED, not started by the assistant. It does not replace the
+installed receiver or its existing preview calculation. The preview/driver must
+only be switched after measurement-boundary and feedback policy acceptance. Model
+training and five-minute reconstruction must consume the new versioned snapshots
+separately; there is no training eligibility or zero future-SDL assumption here.
+
+Device-side command-loss protection and exact model/firmware identification remain
+open. Official SolarEdge PDF fetch was unavailable (403/error); no device-specific
+register suitability or watchdog behavior was inferred from a third-party source.