docs(02): capture phase context

.planning/phases/02-app-core-audio/02-DISCUSSION-LOG.md

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+# Phase 2: App Core + Audio - 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:** 02-app-core-audio
+**Areas discussed:** Choreography format, Audio pipeline, Playback clock, CLI interface
+**Mode:** auto (all areas auto-selected, recommended defaults chosen)
+
+---
+
+## Choreography File Format
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Pydantic JSON with event list | Structured, validated, sorted events | [auto] |
+| YAML with event list | More human-readable but slower parsing | |
+| SQLite database | Overkill for file-based storage | |
+
+**User's choice:** [auto] Pydantic-validated JSON (recommended default)
+
+---
+
+## Audio Pipeline
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Separate threads (miniaudio + sounddevice) | Clean isolation, no device contention | [auto] |
+| Single thread with multiplexing | Complex, potential blocking | |
+| Subprocess for audio | Over-engineered for this use case | |
+
+**User's choice:** [auto] Separate threads with call_from_thread bridge (recommended default)
+
+---
+
+## Playback Clock
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Absolute monotonic timestamps | No drift, correct after pause/resume | [auto] |
+| Relative sleep chains | Simple but drifts 100-200ms/minute | |
+| Hardware timer | Overkill for Pi | |
+
+**User's choice:** [auto] Absolute monotonic timestamps (recommended default)
+
+---
+
+## CLI Interface
+
+| Option | Description | Selected |
+|--------|-------------|----------|
+| Simple asyncio REPL | Lightweight, disposable | [auto] |
+| Click/Typer CLI | Over-engineered for testing | |
+| No CLI (scripts only) | Less interactive | |
+
+**User's choice:** [auto] Simple asyncio REPL (recommended default)
+
+---
+
+## Claude's Discretion
+
+- Python package structure, asyncio task organization, Pydantic details, aubio config
+
+## Deferred Ideas
+
+None