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Syplheed-Reborn/docs
Claude (auto-RE) 20299c05a1 re(challenge): the gate is CLEARED STAGES -- my achievement reading was wrong
Third revision of this claim, and this one has the writer.

Word A (singleton +80) has exactly ONE writer in the image. Scanning all 22
callers of the +80 struct copier (0x82175110) for one that stores to the copy's
word 0 gives a single hit, 0x821C1820, inside GamePart_StageClear:

    if (this+1004 & 0x20000) skip           ; already recorded
    copy local = singleton->progress        ; src = obj+80
    local.word0 |= 1 << (this+84)
    if changed: singleton->set(local)       ; assign + async persist

and this+84 is the STAGE NUMBER, by two independent uses: 0x821C1760 indexes a
20-byte per-stage record array with it (this + (x+7)*20, three words plus an
8-byte timestamp -- the savegame's 16x20 SHAB shape), and 0x821C1EEC/0x821C1924
pass it as the index into the config key "STAGE" (0x820A2540), the debriefing's
px_deb_stage01..16 sprite list.

So a challenge mission's REQUIREMENT n means "stage n has been cleared", and the
<24 / >=24 split is the disc's own stage numbering: story 1-16 and tutorial 18-23
in word A, challenge 24-29 as word B bits 0-5. TimeAttack needs stage 16 -- the
last story mission -- and the other five chain off challenge stages 25-29. That
is what the raw numbers suggested in the first place.

REFUTED: "the bit space is the game's 24 achievements". ACHIEVEMENTS_REQUIREMENTS
having 24 entries and the gate splitting at 24 is a COINCIDENCE -- 24 is also the
first challenge stage's id. Nothing copies the Debriefing's masks (+208/+736/+740)
into +80, which is the check that should have preceded the claim.

The achievement work itself stands and is kept, retitled and rescoped in
structures/achievements.md: the XACH table (.pe 0x8FBCBC, 36-byte records,
1000G self-check), the 24 names/descriptions, the on-disc ACHIEVEMENTS_REQUIREMENTS
list, and the XACHIEVEMENT_DETAILS/XAM read path. It just does not gate the
challenge missions.

Still open: word B (+1956) has no known writer -- GamePart_StageClear's
unconditional 1 << x would land a challenge stage on word A bits 24-29, not word
B, so clearing a challenge mission must be recorded by another path (presumably
the one that also stores its Time/Points record).
2026-08-13 19:54:39 +00:00
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