sptos-sched

Coherence-aware scheduler for the SPTOS Cognition Kernel

Overview

sptos-sched implements the SPTOS scheduler from ADR-087 Section 5. It combines three signals to determine task priority: deadline pressure (EDF scheduling), novelty signal (priority boost for genuinely new information), and structural risk (deprioritization when mutations would lower coherence). This is no_std compatible.

Key Features

• Three-signal priority — Deadline pressure, novelty boost, and coherence risk are combined into a single scheduling score
• Partition scheduling — Tasks grouped by SPF mount origin, each partition receives a guaranteed time slice
• Novelty tracking — Embedding-based novelty detection using cosine similarity against recent inputs
• No priority inversion — Capability-based access prevents tasks from blocking on unheld resources
• Bounded preemption — Preemption occurs only at queue boundaries (after send/recv completes)

Dependencies

Key internal dependencies:

• sptos-types — Scheduler types (TaskHandle, TaskPriority, SchedulerPartition)
• sptos-cap — Capability rights for partition access control
• spt-coherence (optional) — Spectral coherence scoring integration

Usage

use sptos_sched::{Scheduler, SchedulerConfig, TaskControlBlock};
use sptos_types::{TaskHandle, TaskPriority, SchedulerPartition};

let mut scheduler: Scheduler<64, 8> = Scheduler::new(
    SchedulerConfig::default()
);
let tcb = TaskControlBlock::new(
    TaskHandle::new(1, 0),
    CapRights::READ | CapRights::WRITE,
    TaskPriority::Normal,
    0, // partition_id
);
scheduler.add_task(tcb).unwrap();

API Reference

Core Types

Type	Description
Scheduler<N, P>	Core scheduler with N max tasks and P max partitions
SchedulerConfig	Configuration (time quantum, decay factor, risk weight)
TaskControlBlock	Per-task state including priority, partition, and novelty score
TaskState	Task lifecycle state (Ready, Running, Blocked, etc.)
PartitionManager	Manages time-slice allocation across partitions
NoveltyTracker	Tracks input novelty via embedding cosine similarity
PriorityConfig	Weights for combining the three priority signals
SchedulerStats	Runtime statistics for the scheduler