Traced, not inferred: TOOL_MANAGER::RunSynchronousAction spins
`while(synchronousControl == STS_RUNNING) { wxYield(); wxMilliSleep(1); }`
(tool_manager.cpp:370-371), and on wasm wxMilliSleep -> nanosleep ->
__wasm_main_thread_yield_ms is an ASYNCIFY PARK OF THE STACK IT STANDS ON —
in a loop, inside a tool body, with a nested wxYield() dispatch running on
top of the parked stack.
The case closes on its callers: they are exactly the tools whose specs died
at D-on — edit_tool_move_fct (move-with-m, presence-locks move),
sch_drawing_tools (draw wires), the drawing/edit tools behind draw-lines.
The pcbnew spec comments already described the symptom from outside ("the
asyncified pointer-move handler") without naming the park; this is it.
So doc 21's K7 "anywhere" class has ONE caller that blocks Phase D, and it
moves first: the wait must yield the owning context instead of sleeping in
place, with the atomic's transition marking it ready. Recorded with the fix
shape, the upstream-divergence question it raises, and the gate that matters
(the KiCad suite's four canvas-tool specs — the harness has no
RunSynchronousAction and stays green either way).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LBjomQfKyRa3jBdeAKpmTw
f6171a7d34