goldeneye-pc-port/AGENTS.md

AGENTS.md — GoldenEye 007 PC Port

What this is

• n64decomp/007: WIP decompilation of GoldenEye 007 (N64), byte-matches US/EU/JP ROMs.
• Active work: PC port modelled on the Perfect Dark PC port (same Rare "Indy" engine family).
• Reference docs: docs/internals.md — architecture, GE-specific RSP deltas, phased plan (§1–§10). docs/dev/findings.md — the Dxx finding log (§F + §H). Look up findings via docs/dev/findings-index.csv (label, one-liner, status; regenerate with tools_pc/gen_findings_index.py), then read only the specific ## Dxx entry (multi-pass labels like D202/D176(a) have large sections — grep within the section or read with offset/limit, don't slurp it whole). Never linear-read. docs/porting-notes.md — the recurring N64→PC bug classes (dense; skim the headers, read what's relevant).
• Current status: the README "Status" section, and docs/dev/LEVEL-STATUS.md for the per-level sweep. Current task + environment: docs/HANDOFF.md (a rolling local working file — may be absent in a fresh clone; fall back to the README "Status" section).
• Dispatching subagents? docs/dev-process.md — task budgets/deadlines, file partitioning, pre-flight, the standard brief template. Every investigation subagent reads docs/porting-notes.md first and appends to it.

Non-negotiables

1. N64 build untouched. Makefile, tools/, rsp/, ld/ belong to the N64 build. Never modify them for the PC port.
2. Game logic is unmodified. The decomp's control flow and behavior are ground truth for 1:1 fidelity — never change them. All N64 hardware dependencies are satisfied by the port/ layer; if a game file seems to need a behavioral change, stop and check the exception below before assuming the fix belongs in port/. Diagnosis is never restricted — only the fix. Trace a bug as deep into src/game state as the evidence leads, and name the exact struct/field/logic responsible, before deciding which of three buckets it falls in (full framing: docs/dev-process.md). Narrow exception (ABI/layout only): the 32→64-bit pointer-width transition forces a small class of mechanical, semantics-preserving edits that cannot be isolated in port/ — any struct-layout or pointer-width-driven misread caused by 32→64-bit widening, whether in a ROM-serialized record (a struct with a 32-bit-pointer field misaligns when read as 64-bit) or a live runtime struct/union (a raw-byte offset alias into a union arm whose true field shifted because an earlier member in the same union widened — the D209/D210/D255 pattern; see docs/porting-notes.md §A1 for the full catalogue and its diagnostic tells). These follow the PD ground-truth pattern (store the embedded address as u32 and cast to a real pointer at the use site; or read the correctly-named/typed field instead of a raw-offset/mistyped alias), change no logic or behavior, and are each documented in docs/dev/findings.md §F/D3x, cross-tagged to §A1 where that pattern applies. A genuine behavioral difference — the decomp's byte-identical code, given verified-correct inputs, still diverging from real N64 behavior — is not covered by this exception and requires the rule-2 sign-off procedure (docs/dev-process.md) before any src/game edit. No other game-code edits are permitted.
3. Region macros mirror the Makefile. CMakeLists.txt REGION_DEFS must match the N64 Makefile's per-region macro set exactly (finding A1). Divergence = silent branch divergence + link failures.
4. src/libultrare/Makefile.libultrare is ground truth for original-vs-Rare libultra files (finding B3). The PC build compiles: libultra/audio, libultrare/audio (drvrNew/env/reverb), libultra/gu, and libultrare/io/vitbl.c only. All other io/ + os/ files are excluded and shimmed in port/src/libultra.c.
5. rsp/graphics/gmain.s is the RSP ground truth — the authoritative reference for which GBI commands GE emits (modified fast3d, 1545 lines). We do not run it on PC; port/fast3d/ replaces it. Use it to validate the software RSP's command decoding and the custom CC/RM modes.

Critical files

File	Role
docs/internals.md	Architecture + RSP deltas + phased plan (§1–§10). Reference, not a linear read.
docs/dev/findings.md	The Dxx finding log (§F/§H); lookups via docs/dev/findings-index.csv.
CMakeLists.txt	PC build (parallel to the N64 Makefile). Source list + REGION_DEFS live here.
port/src/	Shims: libultra.c (OS API), gesched.c (scheduler), n64stubs.c (boot/TLB/FPU/rmon), random.c (PRNG ported verbatim from random.s), ucode.c (microcode segment markers), main.c, video.c, …
port/fast3d/	Software RSP (adapted from the PD port). The main Phase 2 work.
rsp/graphics/gmain.s	GE's RSP ucode — ground truth for GBI/CC/RM.
reference/mouse-injector/	Vendored GEPD-Edition Mouse Injector source (GPLv2, read-only reference — never compile or modify). Ground truth for the mouse-aim model: games/goldeneye.c is the whole GE aim/hipfire/menu model (our D194 mirror); see its README + docs/dev/GEPD-INPUT-PLAN.md.
A local Perfect Dark PC port checkout (fgsfdsfgs/perfect_dark)	Standing reference — consult it whenever a work item has a PD analogue (same Rare engine family): port-layer ground truth (port/fast3d/, crash/system/video), plus copy candidates port/src/preprocess/ (N64→PC asset conversion; filemodel.c is the D43 near-analogue) and mixer.c/input.c/fs.c. Port-layer files only; same family ≠ identical format — validate per field. Full audit: docs/internals.md §2.4.

Build

./build-pc.sh ntsc-final   # or pal-final / jpn-final

Needs CMake + SDL2 + zlib + OpenGL, and must run from the MSYS2 MINGW64 shell (see build-pc.sh header and docs/building.md). ROM goes in ./data/ (not distributed); assets must be extracted from it first (docs/building.md).

Verification ritual (after any build-affecting change)

1. Undefined symbols. Every symbol referenced by the compiled set (see CMakeLists.txt: SRC_GAME, SRC_ENGINE, SRC_LIBAUDIO, SRC_LIBULTRARE_AUDIO, SRC_LIBULTRARE_DATA, SRC_GU, SRC_PORT*) must be defined exactly once in the compiled set or in port/. Symbols that live in EXCLUDED files (libultra/io/*, libultrare/io/* except vitbl.c, libultra/os/*, libultrare/os/*, sched.c, rmon.c, vi.c, src/*.s) must be provided by port/src/libultra.c, gesched.c, n64stubs.c, random.c, or ucode.c.
2. Duplicates. No symbol defined twice across the compiled set (watch sp_* stacks, rmon*, os* shims, segment markers).
3. Syntax. Every touched file must parse; ./build-pc.sh is the final word.

Run /linkcheck for this sweep. Record new findings in docs/dev/findings.md §F/§H style (next Dxx label after the last used) and add the label to the §F index.

Phase status (summary — see README + docs/dev/findings.md for detail)

• Phase 0–1.5: done. Build system, boot chain, OS-shim layer, fast3d integration, first frames, full intro rendering.
• Phase 2 (rendering): in progress. All 21 solo levels load + render + survive an unattended window; front end (menu → mission select → briefing → start) is functional; file-backed EEPROM saves work. Cosmetic defects are parked in docs/dev/GRAPHICS-BACKLOG.md.
• Phase 3 (audio + input): input layer done (port/src/input.c); polish bugs open (D118* mouse-look residuals; interactive feel-checks owed). Audio mixer done (libaudio → SDL software mixer, D198–D201); D204 tempo drift fixed + measured; D202 stuck door loop root-caused with a port-side expiration (M-66b) awaiting by-ear verification.
• Phase 4 (saves + polish): file-backed EEPROM done; widescreen, config, rebinding UI outstanding.