With word A = 2 the screen lists Stage01 SELECTABLE, carrying a High Score and a
Best Time, and Stage02-Stage08 GREYED OUT. One cleared stage, one selectable
entry, at the bit index that names it -- the mask's meaning is now visible on
screen rather than inferred from disassembly.
Two runs, identical navigation, fresh boot each:
control word A 0x00000002 -> MISSION SELECT opens normally
poked word A 0xFFFFFFFF -> MmAllocatePhysicalMemoryEx fails on 128 MB,
guest throws, Xenia shows "Disc Read Error"
So last commit's heap failure was caused by the poke, and by a careless one:
0xFFFFFFFF claims stages that do not exist (0, 17, 24-31 in word A). Poking only
real story ids (0x0001FFFE = stages 1-16) does not blow the heap. That the list
screen changes behaviour with the mask is itself evidence word A feeds it.
Getting a trustworthy control took three tries, and every failure produced a
plausible wrong answer rather than an error:
1. the title-glyph oracle fired during the ATTRACT MOVIE, so A was pressed at
nothing and the run "reported 0 failures" for a screen it never reached;
2. Xvfb keeps the previous instance's framebuffer until the new one draws, so
a screenshot seconds after launch showed the OLD run -- "MAIN MENU reached
after 1s", against a process that no longer existed;
3. a single-pixel "is NEW GAME white?" test matched a white LOADING FLASH.
Fixes, all in challenge_probe.sh: blank the root and refuse screen oracles for
the first 40 s; identify a screen by a PATTERN of sampled points (white text AND
the dark panel behind it), not one pixel; require two consecutive samples. The
new oracle was validated offline against all six saved screenshots and accepts
exactly the one real main menu.
General lesson worth the words: a navigation oracle that can only fail by
returning the wrong screen will happily produce a whole run of confident,
meaningless results.
Claude (auto-RE)
3ef2c438ae