Claude (auto-RE)
33ae20896e
Static only. Last commit left "REQUIREMENT is a bit index into a progress bitfield" with the space unidentified. It is the achievement space, and both halves are now readable off the disc and the executable. - GamePart_Debriefing (0x8218CF38-0x82191B18) awards them: sub_8218F9A8 walks the on-disc ACHIEVEMENTS_REQUIREMENTS list (tables.pak #16, schema 744c0519), and for entry index n tests bit n, evaluates the entry when clear, and sets the bit when satisfied. The list is literally ACHIEVEMENT01..ACHIEVEMENT24 -- 24 entries, which is exactly where the challenge gate splits word A from word B. - The XEX carries the definitions: XACH at .pe 0x8FBCBC, 36-byte records {id, name_id, unlocked_desc_id, locked_desc_id, image_id u32, gamerscore u16, pad, flags u32, 16 zero bytes}, strings from one XSTR per language (English is table #5). tools/xach_dump.py parses it. SELF-CHECK: the 24 gamerscores sum to exactly 1000, the retail total -- a wrong stride does not land on a round 1000. - The two sources agree on ORDER independently: the requirement types ShootDownAircrafts 1000/10000, ShootDownShips 100, ShootDownWeight MegaTons, GetAllWeapons and GetAllAchievements line up with ids 19-24 exactly as XACH names them. So bit n <-> achievement n+1 is evidence, not inference. (Those last two are requirement TYPES, not debug cheats, despite how they read.) - Corollary: TimeAttack's REQUIREMENT 16 -- the one value that sits in direct value-before-key adjacency, so it survives IDXD dedup -- is bit 16 = achievement 17, "Solar System Defense Award", i.e. finish the story campaign. The other five values (25-29) are >= 24 and so index word B, a second flag space, plausibly a challenge-clear chain. Still 🟡. REFUTED, from the last commit: the stores to +1956 in 0x822AF278 / sub_822C8748 are NOT this singleton. That object comes from 0x822CEB30, checks a +2652 flag and stores string POINTERS at +1956/+2024 -- and a pointer ANDed with 1<<n is meaningless as a gate. So nothing in the image writes this singleton's +1956 field-wise, and where the mask persists (save vs Xbox profile) is open. XEX imports are by ordinal, so absent XamUser* strings are not evidence either way.
Reverse-engineering knowledge base
This directory is the spec-side of the clean-room: it records what the original Project Sylpheed binary does (behaviour) and how its data is laid out, so that the Rust port can be implemented from these specs without re-deriving anything and without ever copying original code.
It exists to answer one question fast: "do we already know how X works, and how sure are we?"
The one rule that matters
Never document a claim more confidently than the evidence supports, and never paste original code here.
A wrong-but-confident note is worse than no note: someone builds on it and the bug hides for weeks. Every entry therefore carries an explicit confidence and its evidence. This mirrors the project method — measure the oracle, never infer; refute before believing.
Clean-room firewall
- ✅ Allowed: behaviour descriptions, field offsets/types, formulas, state machines,
observed input→output pairs, and references to the original by address
(
sub_821B68C0) or toxenia-rs/sylpheed.db. - ❌ Forbidden here and in
crates/: pasted decompiled C/C++ or verbatim disassembled function bodies presented as the thing to reimplement. Cite the address; describe the behaviour in your own words. Disassembly is a tool for understanding, not a source to copy.
Confidence levels
| Level | Meaning | Bar to reach it |
|---|---|---|
CONFIRMED |
Behaviour verified against ground truth. | ≥2 independent observations or one observation cross-checked against an oracle (canary framebuffer, a known-correct value, a second code path). |
PROBABLE |
Strong single-source inference. | One clean observation, or an unambiguous static read of the disassembly. |
HYPOTHESIS |
Educated guess, not yet tested. | Anything else. Must say what would confirm/refute it. |
Promotion requires new evidence, not re-reading the old evidence. A HYPOTHESIS that
"looks right again" is still a HYPOTHESIS. Only an independent check promotes it.
If evidence later contradicts an entry, demote it and record the contradiction — do
not silently edit the conclusion.
When to document
- Right after a function/structure crosses from
HYPOTHESISto at leastPROBABLE— before moving to the next code path, so the knowledge isn't lost or re-derived. - Whenever confidence changes (up or down) — append to the Evidence log, don't overwrite.
- Not while it's still a pure guess with no evidence — a one-liner in the relevant backlog/plan is enough until there's something to stand on.
What to document
- Functions/code paths →
docs/re/functions/<name>.md(one file per function or tight cluster). - Data structures / formats →
docs/re/structures/<name>.md. - Keep the index in
INDEX.md(one line each: name · confidence · one-line summary).
Use the templates: _TEMPLATE.function.md,
_TEMPLATE.structure.md.
How we find and confirm code paths (the toolchain)
Everything joins on the guest virtual address (PC) — code addresses are fixed by the XEX load, identical across our emulator and canary.
- Static (cheap, try first):
xenia-rs/sylpheed.db(DuckDB: 25 481 functions, xrefs, strings, vtables, imports). Query withxenia-rs/zq.py—zq.py grep <str>,zq.py xref <addr>,zq.py dis <lo> <hi>,zq.py fn <pc>. Entry points are usually a string (zq.py grep MSG_DEMO) or an import (movie/XMA API) xref'd back to the loader. - Dynamic (when static is ambiguous): run
xenia-rswith its probe suite —--pc-probe/--audit-pc-probe-hex(fires at block entry),--mem-watch(mid-block reads/writes of a VA),--lr-trace(call/return chains),--trace-instructions,--dump-addr(read guest memory). These already exist; prefer them over hacking canary. - Oracle (correctness ground truth): canary — the Wine cross-build
xenia-canary/build-cross/bin/Windows/Debug/xenia_canary.exe(the native Linux ELF crashes / does not run — do not use it). This is the only emulator that reaches the in-game menu; ourxenia-rsnever got past the intro video. Use canary to observe output (capture its framebuffer for texture colours), not usually to instrument code — though itsbuild-crosstoolchain does compile, so small C++ probes + rebuild are possible when needed. Run muted, one emulator process at a time, point it at the real ISO (not the symlink).
⚠️ VA-equality caveat: join code by PC (fixed), but never assume a data VA holds the same bytes across emulators — allocators differ. Compare data by content/layout.