star_transfer_call_is_synchronous stages exactly the TOOL_MANAGER shape -
Call() then read Running() on the next line - and pins that a parked caller
resumed by the scheduler is indistinguishable from a synchronous return.
star_transfer_chain pins a three-deep nested call (root -> A -> B and back) in
strict order, with a parked star context proved undisturbed throughout.
A rule learned the hard way here: a fiber entry must NEVER return (emscripten
ends the program if it does), so these bodies park forever once their script
is done, like libcontext's trampoline loops. Getting it wrong wedges the
battery with no output at all.
The fiberRunning assertion flips to the stronger Phase B invariant: once the
pump is quiescent NO fiber is on the CPU, the scheduler is.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EarUW9DS1c1sSW4ZNrkGQS
258cb37487