Review found that revision 2 asserted the property its whole design
rested on. It called the dispatch-name extent "synchronous" and never
checked. A registered handler is arbitrary Lua running inside
pmacs.async and may call Handle:await(), which parks the coroutine with
the name still pushed --- so every tick callback and every other
coroutine allocating a job in the meantime inherits it. The existing
tests already await inside pcall, so this is the ordinary shape of an
awaiting handler, not a corner case.
Rule 1 now enforces non-yieldability instead of assuming it, and the
enforcement was already in this file: Handle:await refuses to run
inside pmacs.window.commit_to (async.lua:87-90), with a comment giving
exactly this reasoning --- yielding "would restore the scope while this
coroutine is still parked". _in_dispatch_name_scope joins
_in_commit_scope in the same place.
Three details decide whether the guard holds, and all three are pinned:
it rejects before the park, not after; it rejects unconditionally
rather than only when the handle is incomplete, because a guard keyed
on whether the job happened to finish first passes under test and fails
intermittently in production; and it covers both yield points.
That last one is a finding. pmacs.async.yield_to_next_tick
(async.lua:243-245) also yields and is public. Guarding only await
would have left the hole open through a second door.
Which exposes Q#W-7: the existing commit_to guard has exactly that gap
today. yield_to_next_tick carries no _in_commit_scope refusal, so
Journey Stage 1a Q#JR14b invariant has a second entrance. Reported
rather than patched, and reachability by a real caller is explicitly
UNPROVEN --- it is a code reading, not a repro. My vote is to fix it in
this lane since the lane already edits that function family, but it is
another lane invariant so it is a question.
Q#W-5 justification is rewritten rather than left standing. It argued
parent was deferrable because its ambient would span asynchronous
lifetimes while this one did not --- an argument revision 2 was not
entitled to make, since its own ambient could be parked by any awaiting
handler. With rule 1 the distinction is real: this extent cannot be
suspended, and parent cannot be rescued by refusing to yield because
yielding is the mechanism it needs.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
Levi Neuwirth
7730f87bba