Joe DiPrimaandClaude Fable 5
bc27313f20
Audit of what actually landed in context/ versus what only ever got said in
chat. Five gaps and one stale claim repeated in four files.
New env gates were the biggest hole -- BT_TORSO_LOG, BT_MYOMERS_LOG,
BT_MYOMERS_REPAIR_TEST, BT_SELF_DAMAGE and BT_POWER_DETACH_TEST were all in the
code and none of them in decomp-reference §6, which is supposed to be the hub.
Added with the reasoning that makes them usable: why the myomers probe samples
every frame while unpowered (the NoVoltage window is about a second and a 1 Hz
probe steps straight over it), why the repair test also forces Manual (or
AutoConnect restores power a frame later), why SELF_DAMAGE latches off at the
first death, and why DETACH_TEST taking a NAME is what proves failover rather
than a same-generator re-attach.
The 6am log day was in the code and the player bats but not the KB. Now in
build-and-run with the stem table, the unconditional append, the 8 MB part
roll-over and the BT_LOG-truncates trap, plus the operator-facing note in
operator-console and OPERATOR_GUIDE that you ask for the NEWEST log, never
"today's".
Recorded the crash-symbolization gap, which is the one with teeth. BTCrashFilter
writes a stack into the day log and its own comment claims "we hold the PDB". We
do not: no Release PDB is produced at all, and /O2 implies /Oy so the EBP walk is
unreliable anyway. When the Owens crash finally lands we get an address we cannot
resolve. Written down with the fix (/Oy-, /Zi + /DEBUG, archive the PDB per
build) rather than left as something I mentioned once.
New gotcha 22: HeatModelOff() reads simulationState == 1, i.e. "am I destroyed",
and has nothing to do with the heat model. Behaviour at the call sites is right,
the name is not, and while chasing #70 it reads as "novice pilots cannot twist"
and sends you hunting an experience-level bug that does not exist. Same misnomer
in torso/gyro/sensor headers.
Also documented the dist flavor trap, having nearly shipped it myself: mkdist
reads build/CMakeCache.txt, so a tree configured BT_STEAM=OFF silently produces
a -nosteam zip with no play_steam.bat and no steam_api.dll. OFF is the CMake
default; ON is the documented dev state.
Swept the stale `btl4.log` filename out of reconstruction-gotchas,
reconstruction-method, build-and-run and CLAUDE.md itself -- the log has been
<stem>_YYYYMMDD.log since 1777d5a and every "read btl4.log" instruction was
pointing at a file that is no longer written.
checkctx CLEAN.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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62 lines
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---
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id: reconstruction-method
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title: "Reconstruction Method — the loop, the no-stand-ins rule, decomp technique"
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status: established
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source_sections: "PROGRESS_LOG.md §10b, §5a (decompilation), §10c"
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related_topics: [reconstruction-gotchas, decomp-reference, source-completeness]
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key_terms: [decomp, oracle, bridge, BTL4OPT, WinTesla]
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---
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# Reconstruction Method
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How the missing BT game logic is rebuilt from the binary. The governing rule: **no stand-ins.**
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Full detail: `docs/PROGRESS_LOG.md §10b`; the systemic bug classes are [[reconstruction-gotchas]].
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## The loop (per feature)
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1. Read the RAW decomp `reference/decomp/all/part_*.c` for the relevant `FUN_xxxx`.
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2. Map `FUN_`/`DAT_`/`this+0xNN` to engine symbols using: the BT headers + the WinTesla MUNGA
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source + `game/reconstructed/CLASSMAP.md` + **RP's parallel code** (VTV≈mech, WEAPSYS≈weapons).
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3. Write the **real** reconstruction into `game/reconstructed/*.cpp`.
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4. Build; run env-gated; read `content\<stem>_YYYYMMDD.log` (grep `[anim]/[drive]/[target]/[fire]/[damage]` markers).
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5. cdb on any crash. `static_assert`-lock the layout against the binary's offsets. [T2]
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## RULE: no stand-ins
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The full game logic IS in the pseudocode (the binary ran the game); a "gap" is a reconstruction
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stub not yet filled, not a hole in the original. **Never write stand-in/placeholder logic for an
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apparent gap — read the decomp.** (User: "there are no gaps, just work to be done.") Bring-up
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scaffolding (the `BT_AUTOFIRE`/`BT_AUTODRIVE`/`BT_GOTO` env harness; historically
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explosion-for-beam and a player-gated drive, since replaced by the real reconstructions) is
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clearly MARKED and meant to be REPLACED by the real reconstructed system, never to substitute
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for reading the decomp. [T2]
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## Decompilation stack (established)
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- **Ghidra 12.1.2 + JDK21** are an EXTERNAL install (`tools/` holds only python utilities); the
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headless scripts live in `reference/ghidra_scripts/` (`ExportBTSource.java`, `DecompVSS.java`,
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`ExportAll.java`). `ExportBTSource.java` run headless on `BTL4OPT.EXE` → decompiled C in
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`reference/decomp/` (`bt_<src>.cpp.c` assert-anchored files; bulk pseudocode in
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`reference/decomp/all/part_*.c`). The pass is **assert-anchored** (few funcs/file — anchored
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on the asserts that carry source paths). [T2]
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- For a `FUN_` the assert-anchored exporter skipped: **`tools/disas2.py <VA> [len]`** (capstone
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disassembly of `BTL4OPT.EXE` — recovers x87 math Ghidra drops, folds known calls + float
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constants). Or `DecompVSS.java` (headless address-list decompiler). [T2]
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- **Resolving a `.data` fn-pointer** (a `PTR_LAB_xxxx` callback/vtable slot the decomp didn't
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export): PE-parse the DWORD at its VA, then capstone-disassemble the target. Used for the gait
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callbacks (`@0x4a6d8c`), the valve handler (`@0x4ae464`), gauge widget slots. [T2]
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- **`.data` float constants** are the biggest "couldn't recover" bucket (tuning values); read them
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as the x87 80-bit `float10` the decomp uses, not 32-bit float (`scratchpad/rdtbyte.py`). [T2]
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## Effort model (honest)
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~0.5-1.5 hr/module → ~30-50 agent-hours + human review for ~40 modules, with a long tail (modules
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with no surviving `.HPP` fragment, or split across decomp windows, cost more). Process upgrades:
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per-class function lists (not address clusters), complete vtable rows, recover `.data` constants. [T3]
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## Workflows (for scale)
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For exhaustive multi-function decomp analysis, fan out a **read-only Workflow** (understanding
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phase — one agent per function/class produces an offset map + findings, + an adversarial verify),
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THEN implement hands-on so each change is visible + consistent. This is the §10c pattern; used for
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the ground-model decode (10 agents), the alarm-unification (8), the gauge-widget decode (6). [T2]
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## Key Relationships
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- Bug classes: [[reconstruction-gotchas]] (check FIRST). Reference data: [[decomp-reference]].
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- Why it's needed: [[source-completeness]].
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