docs(01): capture phase context

.planning/phases/01-esp32-firmware/01-DISCUSSION-LOG.md

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+# Phase 1: ESP32 Firmware - Discussion Log
+
+> **Audit trail only.** Do not use as input to planning, research, or execution agents.
+> Decisions are captured in CONTEXT.md — this log preserves the alternatives considered.
+
+**Date:** 2026-04-03
+**Phase:** 01-esp32-firmware
+**Areas discussed:** Animation design, JSON protocol, Power & safety, Development setup
+**Mode:** auto (all areas auto-selected, recommended defaults chosen)
+
+---
+
+## Animation Design
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Palette-based with RGBW | Each animation accepts color palette + params | [auto] |
+| Single color per animation | Simpler but limiting | |
+| HSV color space | Alternative representation | |
+
+**User's choice:** [auto] Palette-based with RGBW support (recommended default)
+**Notes:** SK6812 is RGBW — palette approach keeps JSON commands simple while supporting rich effects. W channel auto-derived from RGB when not specified.
+
+---
+
+## JSON Protocol
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Flat JSON | `{"zone":"wall","animation":"chase","params":{}}` | [auto] |
+| Nested/hierarchical | More structured but complex | |
+| Binary protocol | Lower overhead but harder to debug | |
+
+**User's choice:** [auto] Flat JSON with zone, animation, and params fields (recommended default)
+**Notes:** Matches research recommendation. Simple, debuggable with netcat.
+
+---
+
+## Power & Safety
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| 40% brightness cap | Safe for power budget | [auto] |
+| No cap (user responsibility) | Full brightness available | |
+| Dynamic cap based on animation | Complex but optimal | |
+
+**User's choice:** [auto] 40% firmware-enforced cap, adjustable to max 60% (recommended default)
+**Notes:** Research flagged 27A peak at full brightness across 460 LEDs.
+
+---
+
+## Development Setup
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| PlatformIO + Arduino | NeoPixelBus + ArduinoJson ecosystem | [auto] |
+| ESP-IDF native | More control, steeper learning curve | |
+| Arduino IDE | Simpler but no dependency management | |
+
+**User's choice:** [auto] PlatformIO + Arduino framework (recommended default)
+**Notes:** Research validated NeoPixelBus RMT + ArduinoJson work well on ESP32-C3.
+
+---
+
+## Claude's Discretion
+
+- FreeRTOS task priorities and stack sizes
+- GPIO pin assignments (hardware validation needed)
+- DMA buffer sizing for RMT
+- WiFi reconnection strategy
+
+## Deferred Ideas
+
+None — auto mode, discussion stayed within phase scope