ADR-0008: Deterministic execution & replay

Status

Accepted

Context

Fault isolation and neighbor recovery require bit-stable state transitions across heterogeneous CPUs.

Decision

• Append-only BLAKE3-chained TxLog for task mutations; recovery = verify + replay.
• Immutable sealed memory regions in CNK.
• Consensus math prefers Q16.16 FixedPoint; SoftF32 canonicalizes NaN/−0 but is not claimed bit-identical across all FPUs for long chains.
• Degradation policy downsamples / forces fixed-point on low-RAM / no-FPU profiles instead of dropping tasks.

Consequences

• Host tests prove replay recovery.
• Cross-arch float consensus should use FixedPoint, not host f32 sin chains.