Add main interface spec

docs/specs/main-interface-spec.md

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+# Main Interface Specification
+
+**From Initial Inventory Interview through Complete Dashboard Experience**
+
+**Status**: Draft
+
+## Overview
+
+This document defines the end-to-end user experience from the moment a new water system is onboarded through daily dashboard usage for both owners and operators.
+
+## 1. Initial Inventory Interview (Onboarding)
+
+The system uses a guided, AI-assisted interview to build the initial model of the pumphouse.
+
+Key steps:
+- Identify major components (pumps, filters, tanks, meters)
+- Map signals to components
+- Define healthy vs unhealthy ranges (with AI recommendations + user override)
+- Set up basic alerts
+- Configure camera-based sensors if used (OCR or needle gauges)
+
+## 2. Dashboard Philosophy
+
+Two modes:
+- **Basic Mode** (default for owners): 10,000-foot view — simple health status, current key values, active alerts
+- **Advanced Mode** (default for operators): Detailed trends, per-component cards, historical data, configuration access
+
+Users can toggle between modes, and their preference is remembered.
+
+## 3. Monitored Objects
+
+First-class concept. Every pump, filter, tank, or sensor group is a Monitored Object.
+- Can have relationships to other objects
+- Has its own visualization card
+- Has its own alert rules
+
+## 4. Key Dashboard Sections
+
+- Overall system health
+- Active Alerts
+- Component cards (pressure, flow, amps, levels, etc.)
+- Quick links to historical data and alert history
+
+**Related**: See `alerts-spec.md` for alert workflows and `pumphouse-use-cases.md` for persona details.