10. Live performance (added in the 2026-07-21 follow-up interview)

The primary real-world use is live DJ shows: the app renders to a projector/LED screen while a DJ mixes. This adds:

• Session stability: no crash, leak, or visual degradation over a ≥ 4-hour continuous session. A soak test becomes part of the live-features plan’s done-when.
• Inputs (all three, core stays source-agnostic): loopback (DJ software on the same machine), line-in via an audio interface (cable from the mixer’s booth/rec out — the robust stage setup; needs a capture-device path alongside loopback), and the foobar plugin.
• Scene triggers, layered: auto-rotate (MilkDrop-style timing, biased toward energy shifts/drops) as the baseline; manual trigger (hotkey, MIDI worth exploring) as the override; best-effort track-change detection (long-window spectral/tempo novelty) as an experimental extra — never the only mechanism, since beatmatched blends have no hard boundary.
• Projector output is first-class: fullscreen-on-chosen-display matters more than desk UX; it moves early in the roadmap.
• Scenes are presets, not code (target state): visualizations will be authored as lightweight MilkDrop-akin preset files with an optional scripting layer for staged, coherent per-track arcs and generative systems (walkers, flocks, 3D). Exact shape under exploration; the decision will land as an ADR before the preset-engine plan is drafted. Plan 0001’s built-in Rust scenes remain the walking skeleton and later become the rendering vocabulary presets drive.