🎹 ISLA v3.1.1 — LIVE Continuity & Recovery

Let the Music Flow. Even When the Audio Stream Stumbles.

ISLA v3.1.1 is a focused reliability patch for the experimental LIVE audio-monitoring engine.

Following v3.1.0's DSP stability improvements, this release addresses an issue discovered during real-world macOS listening: a single BlackHole capture-overflow event could cause ISLA to terminate monitoring, interrupting playback and requiring a manual restart.

Version 3.1.1 introduces bounded recovery from isolated capture interruptions, stronger audio-state protection, and expanded diagnostics—without changing the musical character of ISLA.

🔧 What's Fixed

1. Recovery From Isolated Capture Interruptions

Previously, a reported input overflow or underflow after startup caused LIVE to shut down immediately.

ISLA now attempts controlled recovery when a capture discontinuity is isolated and the audio system remains in a valid state.

The recovery sequence:

Rejects the affected audio block and outputs silence during recovery.
Prevents queued or in-flight audio from the previous stream state from being replayed.
Clears application audio queues.
Rebuilds the DSP's history, overlap-add state, and delay buffers.
Revalidates device identity and routing.
Resumes processing from fresh incoming audio when recovery succeeds.

Lost audio is not reconstructed or concealed as though no interruption occurred. A brief audible gap may remain.

2. Bounded, Safety-Conscious Recovery

To prevent repeated failures from becoming an unstable monitoring loop, recovery follows strict limits:

A minimum 10-second healthy interval between accepted capture interruptions.
No more than three recovery attempts per explicitly started monitoring session.
Recovery must complete within eight additional audio callbacks.
Persistent or repeated discontinuities trigger a safe shutdown.

At 48 kHz, the eight-callback recovery deadline is approximately 85 milliseconds.

Unsafe routing, disconnection, invalid timestamps, buffer failures, and persistent starvation remain fatal conditions.

The existing BlackHole single-path safeguards and physical-output restrictions are unchanged.

3. Improved Audio Diagnostics

The status command now provides more detailed visibility into LIVE monitoring.

New diagnostic information distinguishes:

Driver-reported input and output overflows/underflows.
Application ring-buffer failures.
Capture-discontinuity events.
Recovery attempts, completions, and failures.
Deliberately silenced and discarded audio blocks.
Fatal device errors.
The last interruption and recovery state.
Maximum observed worker, routing, and queue timing.

A successfully recovered session is explicitly identified as Recovered (audio lost), rather than being misrepresented as uninterrupted playback.

4. Native Reliability Testing Support

A new scalar-only reliability probe, tools/live_reliability_probe.py, supports longer monitoring observations.

It records diagnostic counters, timing, operating environment, and recovery state without recording or saving the user's music.

A companion native macOS checklist covers Bypass, Velvet, Legato, Melt, physical device changes, extended playback, and recovery behavior.

These tools provide a more systematic way to evaluate the reliability of ISLA on actual Mac hardware.

🧪 Testing and Engineering Evidence

The implementation includes additional deterministic tests covering isolated and repeated capture loss, recovery deadlines, stale-audio prevention, DSP state reset, buffer contention, device faults, mode switching, and normal uninterrupted processing.

Recorded validation includes:

305 passing Python tests
1 unchanged expected failure
36 passing focused recovery tests
Successful four-platform hosted ALIVE Python acceptance on the merged implementation
Worker-only performance benchmarking at 44.1 and 48 kHz

The normal LIVE processing window, hop size, algorithmic delay, musical profiles, and DSP equations remain unchanged.

Bypass continues to preserve its original exact waveform behavior when capture is uninterrupted.

⚠️ Known Limitations

ISLA LIVE remains experimental.

Native Core Audio and PortAudio scheduling, device-driver buffering, physical latency, and actual hardware reliability can differ from simulated testing.

This patch does not guarantee uninterrupted playback, recover missing samples, eliminate audible gaps, or make Python audio processing hard real-time.

Sustained native Mac listening acceptance is still required to establish whether the original intermittent shutdown is reliably mitigated on the creator's hardware.

❤️ Continuing the ISLA Journey

The foundation of ISLA is not only musical experimentation. It is dependable engineering.

Version 3.1.0 strengthened the mathematical behavior of ISLA's audio processing.

Version 3.1.1 strengthens how LIVE responds when the surrounding audio system encounters a temporary interruption.

That reliability work supports the next chapter: exploring more distinctive musical identities for Velvet, Legato, and Melt.

Dedicated to Isla, whose name continues to inspire the project.