Flow · W-01 Direct I/O
0 / 0
IoContext ownership boundary · Core + Backend + ProgressSource
Application
调用方 · 显式选择执行
File / buffer owner
·File
native resource + access facts
RAII owner
·Direct adapter
caller-thread execution
completed return
·Linux regular file
physical effects / result
ordinary-file domain
·Progress owner / Host
fixed exclusive context driver
external loop / optional host
·IoContext
identity / budgets / health
owns core, backend, source
·RequestCore
accept / result / publish
semantic authority
·ThreadPool
bounded worker offload
physical mechanism
·Request<T>
unique public result binding
settlement responsibility
·Observer protocol
attach / deliver / retire
notification ≠ ownership
·ProgressSource
persistent pollable signal
progress ≠ terminal
·Request #1 · distinct milestones逻辑顺序 / 状态，不表示耗时或唯一调度
实线包：当前 handoff · 仅亮节点：本地状态变化 · 虚线：本流程其他 handoffs · 淡化：不参与。位置可拖动；底层语义不随 backend 改变。