The other half of the same measurement. `wXCoord` and `wYCoord` are the tile the step began on
until the frame it ends, so the stood ledger recorded ground the fly had already left and the tile
under it stayed unstood: `path::frontier` kept offering it, `GO FRONTIER` was dealt aiming one tile
away, and `Arrival::Step` reported `done` the instant the step it did not make landed. A macro that
completes without changing anything, which is section 12.2's trap.
A step that has begun always finishes -- the cartridge owns the animation and no press stops it --
and the screen has already centred on the tile, so it is ground this run has covered. It clears the
map's frontier mark on the same rule the coordinates do: only ground never stood on before.
Two Stuck rollbacks fired on rung 10 inside half an hour, both on a fly that was walking, and
both were the ratchet working to contract: the stall window is reset by exploration -- one tile
the run has never stood on -- and a fly crossing a town it has already covered to reach the
rung's own door earns none of it. Entering a map for the first time already counts, because a
new map is ground nobody has stood on; re-entering one does not, which is what the museum was.
So the window gains a second signal, passed in by the caller and meaningless to the ratchet
itself, exactly as coverage is: the Pokemon loop answers with "nearer the objective, in map
hops, than this run has ever been", over the same map graph GO OBJECTIVE walks. It can fire at
most once per step of the road, it spends no budget, it captures nothing and it skips no
trigger. Nothing in the macro layer reads it back and no button is bound on it.
The checkpointed ratchet state is untouched: the signal is a level on one sample, not a counter.
GO FRONTIER was 1,235 of the rung-10 run's macro starts in 47 minutes, over two museum floors
and a town whose ground the fly had already covered. The tiles it aimed at were real and
unreachable: 98 walkable tiles on the museum's ground floor, 62 of them reachable from the door,
39 never stood on and almost all of those behind the admission desk. A walk that can reach none
of its goals refuses no route and writes every goal to the blocked ledger -- which is a ten
brain minute window, so all of it came back and the refusal happened again, once per hold.
A window is right for a target somebody is standing in front of and wrong for ground the map has
fenced off. So the refusal is remembered per map instead, with no window, and it is cleared by
the one event that can change the answer: the fly standing somewhere on that map it had not
stood on before -- a door opened, a script carried it through, somebody moved out of a doorway.
Re-entering the map clears nothing, which is the loop the window made.
The walkable predicate answered for the ten-by-nine screen window and Unknown
everywhere else. MapGrid is the same rule over every tile of the loaded map:
block ids out of wOverworldMap, a blocks-to-tiles read of the tileset header s
blockset through the new bank-aware ROM read, the tileset s collision list as
before, and the TilePairCollisionsLand values as directed walls both ways.
The reader checks itself before it answers: the decode is compared against the
window predicate over the player s own neighbourhood, and a frame where the
window can answer for none of it -- a battle, a text box, a frame mid-warp -- is
refused, because wOverworldMap shares its bytes with the picture buffer. Every
refusal is named (GridRefusal) and leaves the window predicate in charge.
Cached per map id and size, so a map is decoded once on arrival rather than once
per question, and owned beside the session ledgers: never checkpointed.
