@startuml
!include card-uml-style.iuml
scale 900 width
left to right direction

class "01  timer CSRs" as Timer <<runtime>> {
  mtime
  mtimecmp
  mcause = 0x80000007
  mepc = interrupted task PC
}

class "02  ISR evidence" as ISR <<runtime>> {
  first_tick_count
  ISR sp
  one-shot tick checkpoint
}

class "03  scheduler evidence" as Kernel <<debugger only>> {
  Ready lists by priority
  selected TCB
  tick count
}

class "04  peer runtime" as Peer <<runtime>> {
  context address
  handle / TCB
  task stack range
  PC · SP · priority 2
}

class "05  high runtime" as High <<runtime>> {
  handle / TCB
  priority 0 → 3
  PC · SP · run_tick
}

class "06  committed evidence" as Evidence <<application>> {
  switch trace A · B · A
  markers before · HIGH · after
  source blob · ELF hash
  PASS
}

Timer --> ISR : machine-timer trap
ISR --> Kernel : scheduling opportunity
Kernel --> Peer : equal-priority rotation
Kernel --> High : select after priority raise
Peer --> Evidence
High --> Evidence

note bottom of Kernel
  Kernel internals are debugger observations only.
  Program assertions use public API and application records.
end note
@enduml