parity.rs replays the four committed stage fixtures whose headers the Rust
producer can read (macros, shop, center, bigpad; 400 snapshots each, all of
them with FLY_EDGE_PARITY_ALL=1) into one watch slot served both ways at once,
recorded by a stage, a bridge and a frame-only client per path: headers equal
without wall times, attachments byte-equal and equal to the fixture's, and
the whole messages byte-equal. FLY_EDGE_PARITY_OUT writes the recordings as
.flyfeed files. Also: a header past the envelope limit, and the edge dropping
its clients, unbinding and coming back across a router restart.
stall.rs runs flysim's Pacer at 60 Hz publishing full-size snapshots at 30 Hz
against three stages that stopped reading, a bus subscriber that hoards every
delivery, and no subscriber at all: pacer lag 0, no slow watch send, no
refused publication, a bounded store, and a healthy client that stays current.
