Initial commit: Sentry-Emote system monitor

- Aggregator: Flask-based event broker with priority queue
- Frontend: OLED-optimized UI with animations
- Detectors: disk, cpu, memory, service, network
- Unified entry point (sentry.py) with process management
- Heartbeat TTL system for auto-clearing stale events

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

SPEC.md

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+# SPEC.md: Project "Sentry-Emote"
+
+## 1. Overview
+
+**Purpose:** Repurpose an old Pixel phone (OLED screen) as an ambient, glanceable system status monitor for a home server.
+**Design Philosophy:** Minimalist, binary-state, and high-signal. Use an "Emote" (ASCII/Emoji) to represent system health instead of complex graphs.
+**Target Device:** Android Pixel (accessed via Fully Kiosk Browser).
+
+## 2. System Architecture
+
+The system follows a decoupled **Publisher/Subscriber** model to ensure extensibility.
+
+- **Aggregator (The Broker):** A central Python service running on the server. It manages the event queue and generates the state.
+- **Detectors (The Publishers):** Independent scripts (Python, Bash, etc.) that monitor specific system metrics and "hook" into the Aggregator.
+- **Emote-UI (The Subscriber):** A mobile-optimized web frontend that displays the current highest-priority emote.
+
+## 3. Data Specification
+
+### 3.1 `status.json` (State Registry)
+
+The Aggregator outputs this file every time the state changes.
+
+```json
+{
+	"current_state": "optimal",
+	"active_emote": "( ^_^)",
+	"color": "#00FF00",
+	"animation": "breathing",
+	"message": "All systems nominal",
+	"active_events": [
+		{
+			"id": "disk_check",
+			"priority": 4,
+			"message": "Disk 40% full"
+		}
+	],
+	"last_updated": "2026-02-02T17:30:00"
+}
+```
+
+### 3.2 Priority Hierarchy
+
+| Level | Name         | Priority  | Emote    | Color  | Logic                                    |
+| ----- | ------------ | --------- | -------- | ------ | ---------------------------------------- |
+| **1** | **Critical** | Emergency | `( x_x)` | Red    | Overrules all. Manual clear required.    |
+| **2** | **Warning**  | Caution   | `( o_o)` | Yellow | Overrules Optimal. Auto-clears if fixed. |
+| **3** | **Notify**   | Event     | `( 'o')` | Blue   | Transient. TTL (Time To Live) of 10s.    |
+| **4** | **Optimal**  | Default   | `( ^_^)` | Green  | Active when no other events exist.       |
+
+## 4. Component Requirements
+
+### 4.1 Aggregator (`aggregator.py`)
+
+- **Event Bus:** Accept HTTP POST requests or watch a specific file/directory for new event signals.
+- **State Management:** Maintain a list of "Active Events."
+- **TTL Logic:** Automatically remove Priority 3 events after 10 seconds.
+- **Deduplication:** If multiple events exist, always select the one with the lowest priority number for the `active_emote` field.
+
+### 4.2 Emote-UI (`index.html`)
+
+- **OLED Optimization:** Pure black background (`#000000`).
+- **Glanceability:** Massive centered text for the emote.
+- **Animations:** - `breathing`: Slow opacity/scale pulse.
+- `shaking`: Rapid X-axis jitter for Critical.
+- `popping`: Scale-up effect for Notifications.
+
+- **Refresh:** Long-polling or `setInterval` every 2 seconds.
+
+### 4.3 Extensibility (The Hook System)
+
+- New detectors must be able to send an event to the Aggregator without modifying the core code.
+- Example Detector Hook: `curl -X POST -d '{"id":"ssh","priority":1}' http://localhost:5000/event`
+
+## 5. Implementation Roadmap
+
+1. **Phase 1:** Build the `aggregator.py` with basic JSON output.
+2. **Phase 2:** Build the OLED-friendly `index.html` frontend.
+3. **Phase 3:** Create the first "Detector" (e.g., a simple disk space checker).
+4. **Phase 4:** Implement TTL for transient notifications.