Reported symptom: text input in a terminal does not work on the GPU
frontend while the TUI is fine.
Root cause, measured against a real daemon, a real PTY child, and the
real pmacs-gpu attach client: the dispatcher loop applies BOTH
terminal-layout syncs to EVERY attached frontend each tick. A semantic
session satisfies both conditions -- it has a term_sizes entry from
AttachRequest and a semantic terminal declaration -- so the PTY is
resized twice per tick forever, because the grid arm runs the TUI
placement helper that subtracts a modeline the GPU never draws. The
result is a SIGWINCH storm plus screen reflow at tick cadence, which
makes an interactive line editor unusable while child output keeps
flowing. Measured 730 terminal frames in 20 s for a static screen.
Revision 2 answers Q#GT4 from the code rather than deferring it, which
changes the fix from a one-line guard into a split of
sync_terminal_layout: the grid arm is also the only per-tick
controller-liveness release a GPU session gets, and the semantic arm
neither performs it nor can be made to, because the buffer-follow
snapshot clears the viewport declaration that would drive it.
The doc also records three falsified hypotheses, why the Stage 3
real-path acceptance passes on the broken tree, and a COHERENCE.md
section 6 citation error (two replica frontends have two different
optimistic classifiers; the audit names only one).
No code changes in this commit.
