Claude
d90036a0a4
Issue #49: the repos carry code, tooling and docs only. Untracks 143 screenshots, 3 savegame blobs and `tools/re-capture/ob_digits.png` (a digit-template sheet cut from game frames) -- 146 files, 76.4 MB. They stay in the working tree and are gitignored, so the pages' relative links still resolve where the captures exist and nothing ships. Derived measurements (csv/tsv/txt/log/json/jsonl/npy) are our own numbers, not game content, and stay tracked -- they are what most claims rest on. `check-capture-citations` had its contract inverted, and it is the half worth reading: * presence now comes from the WORKING TREE, not `git ls-files`. The assets are deliberately untracked, so asking the index would report every screenshot as missing and fail all 203 citations. * a NEW failure: a game asset that IS tracked. A screenshot that sneaks back in is invisible in review -- a binary shows as "Bin 0 -> 1234567 bytes" -- and is permanent once merged, since removing it later needs a history rewrite. So that half has to be loud. Verified: * selftest 8/8, including the new rule * scan: 212 present, 212 cited, 0 dangling, 0 tracked -> exit 0 * force-add one PNG -> "game assets TRACKED: 1", exit 1, selftest red ⚠️ This does NOT remove the blobs from history; a clone still fetches them. That needs a filter-repo rewrite and a force-push, which is a separate, human-run step. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
6.8 KiB
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.
Captures are local-only (issue #49)
The repository carries code, tooling and docs. Screenshots and savegame
blobs are game-derived, so since 2026-09-19 they live in docs/re/captures/
on disk and are gitignored — the pages' relative links still resolve on a
machine that has them, and nothing ships.
Derived measurements (csv, tsv, txt, log, json, jsonl, npy) are
our own numbers rather than game content, and stay tracked — they are what most
claims here actually rest on.
tools/re/check-capture-citations enforces both halves: a cited capture must be
present, and a game asset must not be tracked. ⚠️ A fresh clone has no
captures, so its citations will not resolve until the captures are copied in;
that is expected, and the checker is a local gate rather than a CI one.
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 tosylpheed.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. |
The status markers
The table above is the confidence scale. The markers that appear in
BACKLOG.md and the structures/ pages are a separate, and until now undefined,
vocabulary. They mean:
| Marker | Meaning |
|---|---|
| ✅ | Confirmed — verified against ground truth. |
| 🟡 | Partial: true as far as it goes, or true under a stated assumption. |
| ❔ | Open question. Nobody has answered it yet. |
| 🔴 | Refuted — shown false — or blocked by something the container cannot do. |
| ❌ | A specific claim that was tried and failed. Prefer 🔴. |
| 🚧 | Work started and not finished. |
🔴 never means "we have not run it yet." That is ❔ or 🚧. Reserve 🔴's "blocked" sense for a real limit of the box — no push credentials, no hardware Vulkan (lavapipe only), or a decision only the user can make. The box can run the emulator, script input, screenshot, read guest memory, and build and test Rust, so "needs a run" is never a blocker. This paragraph exists because the marker was undefined for 98 uses and three of them were mislabelled that way.
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):
sylpheed.dbat the repository root (DuckDB: 25 676 functions, xrefs, strings, vtables, imports; git-ignored — build it withsylph-xexdb dis <ISO> --db sylpheed.db --analyze sql --quiet, then re-stamp names withtools/apply_re_symbols.sql). Query withtools/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): Xenia Canary, below. The
xenia-rsprobe suite this bullet used to recommend (--pc-probe,--mem-watch,--lr-trace,--dump-addr) went with that emulator when it was retired on 2026-09-16. For static.rdatareads that--dump-addrserved, read the.pedirectly: it is a flat VA dump, file offset =VA − 0x82000000. - Oracle (correctness ground truth): canary, in either of two builds — the Wine
cross-build in
xenia-canary/build-cross/bin/Windows/Debug/(launched byrun-canary-safe.sh) or the native Linux build inxenia-canary-native/(launched byrun-canary-native-safe.sh). This is the only emulator that reaches the in-game menu; our retiredxenia-rsnever got past the intro video. Use canary to observe output (capture its framebuffer for texture colours), not usually to instrument code — though both builds compile, so small C++ probes + rebuild are possible when needed. Run muted, one emulator process at a time, point it at the real ISO.
⚠️ 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.