Row 50: MOVE n reported blocked 890 times in 1,431 macros on the cartridge,
every one of them on a frame the seam read as an open move list with a
placeable cursor.
MoveSelectionMenu writes wTopMenuItemY 12 and wTopMenuItemX 5 and nothing in
the game clears them, exactly as the two-option box's geometry outlives its
box. SelectMenuItem then decrements wCurrentMenuItem back to the 0-based slot
on its way out, which lands straight back inside the one-based range the
accessor reads. So the whole of a turn -- the text, the animation, the
enemy's reply -- read as the fly's own turn on an open list, the pad dealt
the four move buttons on it, and the cursor step pressed at a list nobody was
reading until its budget ran out.
The reading is the figure the menu draws, the same construction text_box's
waiting and yes_no_prompt already make: a box at (4, 12) fourteen wide with a
horizontal run over its top-left corner and the junction tile at (10, 12).
Surveyed with one rollback pulse per battle frame over 3,102 frames at the
rung-9 forest checkpoint: by the cursor bytes alone a real directional press
was honoured on 264 of them, and by the cursor bytes and the box on 231 of
231.
A frame whose list is not on screen is between turns, whose pad is the one
NEXT that advances text.
Measured on the cartridge from the rung-10 checkpoint: `wXCoord` and `wYCoord` change at the *end*
of a sixteen-frame step while the background scrolls throughout it, so for fifteen frames of every
sixteen the screen buffer is centred one tile ahead of the coordinates. The cross-check compared
the decode of the fly's own tile with the screen's reading of the tile ahead and refused. Pewter
City decoded on 118 of 120 standing frames and on none of the moving ones, so every walk the fly
actually took was re-planned over the ten-by-nine window, which is the oscillation of row 23.
Nothing in the pinned symbol table says "a step is in progress" and a new address cannot be pinned
without the disassembly `gen_symbols.py` reads, so the anchor is measured rather than named: the
screen is centred on the fly's tile or on one of its four neighbours, and the one it is centred on
is the one whose whole neighbourhood agrees with the decode. A decode with a wrong stride, a wrong
quadrant or a half-loaded map agrees with none of the five, and neither does the mid-warp tear the
per-serve check was added for, so both refusals stand.
`state::step_destination` names the tile the step is landing on, for the ledger the next commit
writes. The town fixture gains two landmarks beside the fly, because a neighbourhood that is the
same tile id in every direction cannot tell one anchor from another.
Measured on the cartridge, not derived: a map tile is 2x2 screen tiles and
CheckTilePassable matches one id, and the screen agrees with the lower-left tile
of the quadrant. Viridian Forest s (4, 32) reads 3, the second row of its
block, where the first row holds bash4. On open ground most quadrants hold one id
four times over, so the upper-left guess reads correctly on a town and falls
apart in a forest -- which is why the decode is cross-checked against the screen
before it is trusted.
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.
