- five decisions: head auto-registers with opt-out (+ patch/options/all);
request ids mirror limiter trust model with a NON-crypto source; per-route
body_limit is a SECOND check after routing (global BODY_MAX stays the
pre-routing ceiling, over-limit = 413); Route fields are corpus-free;
Vary accumulates by comma-join
- key finding: story 5 has NO upstream dependency, not even iteration 2 --
request ids are not secrets, so a non-crypto source (time.ticks+counter)
keeps it startable today; the one porch slice buildable right now
- three story assumptions corrected: per-route limit cannot replace the
global (body read before routing); the container-owned-move corpus fixture
has its OWN Route (adding fields is free); Vary needs no iteration 2
- validated against .dev/reference/fiber; zero language enhancement. Board synced
(cherry picked from commit 0589a13db1f3b7c220d9d9fdc76142af6a63c390)