docs: initialize project wiki from production hardening session

12 pages covering architecture, findings, and metrics from the
rotatingMachine + machineGroupControl hardening work:

- Overview: node inventory, what works/doesn't, current scale
- Architecture: 3D pump curves, group optimization algorithm
- Findings: BEP-Gravitation proof (0.1% of optimum), NCog behavior,
  curve non-convexity, pump switching stability
- Metrics: test counts, power comparison table, performance numbers
- Knowledge graph: structured YAML with all data points and provenance
- Session log: 2026-04-07 production hardening
- Tools: query.py, search.sh, lint.sh

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

wiki/overview.md

@@ -0,0 +1,70 @@
+---
+title: EVOLV Project Overview
+created: 2026-04-07
+updated: 2026-04-07
+status: evolving
+tags: [overview, wastewater, node-red, isa-88]
+---
+
+# EVOLV — Edge-Layer Evolution for Optimized Virtualization
+
+Industrial automation platform for wastewater treatment, built as custom Node-RED nodes by Waterschap Brabantse Delta R&D. Follows ISA-88 (S88) batch control standard.
+
+## Stack
+
+Node.js, Node-RED, InfluxDB (time-series), TensorFlow.js (prediction), CoolProp (thermodynamics). No build step — pure Node.js.
+
+## Architecture
+
+Each node follows a 3-tier pattern:
+1. **Entry file** — registers with Node-RED, admin HTTP endpoints
+2. **nodeClass** — Node-RED adapter (tick loop, message routing, status)
+3. **specificClass** — pure domain logic (physics, state machines, predictions)
+
+3-port output convention: Port 0 = process data, Port 1 = InfluxDB telemetry, Port 2 = parent-child registration.
+
+## What Works
+
+| Capability | Status | Evidence |
+|---|---|---|
+| rotatingMachine state machine | proven | 76 tests passing, all sequences verified |
+| 3D pump curve prediction (flow/power from pressure+control) | proven | Monotonic cubic spline interpolation across 34 pressure levels |
+| NCog / BEP tracking per pump | proven | Produces meaningful values with differential pressure |
+| machineGroupControl BEP-Gravitation | proven | Within 0.1% of brute-force global optimum |
+| Combination selection (2^n exhaustive) | proven | Stable: 1-2 switches across 5-95% demand sweep, no hysteresis |
+| Prediction health scoring | proven | NRMSE drift, pressure source penalties, edge detection |
+| Hydraulic efficiency (η = QΔP/P) | proven | CoolProp density, head calculation |
+| Unit conversion chain | proven | No double-conversion, clean layer separation |
+
+## What Doesn't Work (honestly)
+
+| Issue | Status | Evidence |
+|---|---|---|
+| C5 curve non-convexity | evolving | 5 raw data points cause spline artifacts, dP/dQ non-monotonic |
+| NCog = 0 at high ΔP | evolving | At ΔP > 800 mbar for H05K, Q/P is monotonically decreasing |
+| calcBestCombination (NCog-weight mode) | disproven | Uses NCog as proportional weight instead of BEP target |
+
+## Current Scale
+
+- 13 custom Node-RED nodes (12 submodules + generalFunctions)
+- rotatingMachine: 76 tests, 1563 lines domain logic
+- machineGroupControl: 90+ tests, 1400+ lines domain logic
+- 3 real pump curves: H05K-S03R, C5-D03R-SHN1, ECDV
+- Tick loop: 1000ms interval
+
+## Node Inventory
+
+| Node | Purpose | Test Status |
+|------|---------|-------------|
+| rotatingMachine | Pump/compressor control | 76 tests (full) |
+| machineGroupControl | Multi-pump optimization | 90 tests (full) |
+| pumpingStation | Multi-pump station | needs review |
+| valve | Valve modeling | needs review |
+| valveGroupControl | Valve group coordination | needs review |
+| reactor | Biological reactor (ASM kinetics) | needs review |
+| settler | Secondary clarifier | needs review |
+| monster | Multi-parameter bio monitoring | needs review |
+| measurement | Sensor signal conditioning | needs review |
+| diffuser | Aeration system control | needs review |
+| dashboardAPI | InfluxDB + FlowFuse charts | needs review |
+| generalFunctions | Shared utilities | partial |