D303: investigate extra long muzzle flash — pipeline + data ruled out; GE_D303 capture probe in-tree

docs/dev/V0.4.0-PLAN.md

@@ -29,7 +29,7 @@ Sequencing follows M-139's R → Q → F order, split into four phases below.
 | D320 | 17 aim-hold AI lists in 8 levels carry the as-authored D318 softlock race; Facility `ai_19`, Control `ai_9`, Depot `ai_12` high/med-high | Static sweep done; **live probe-verification owed** (GE_D318T-style timeline on the 3 lists). If one freezes: generalize `d318watchdog.c` (parameterize list/offset/chr/entityid), not per-list copies. N64 softlocks permanently — watchdog stays a port-side recovery, disclosed like D318. |
 | D252 | Rainbow particles still intermittent on both platforms after the vertex-buffer fix | Second cause unrooted; prime suspect `import_texture_rgba16` fire-tile width/height from tile line size (32×7 vs 16×14). README known issue. |
 | D245 | Water seam between two patterns, moves with view (REOPENED) | M-142 probe: tc-shift k flips during ordinary rotation; opt-in `GE_D245_FIXEDSHIFT` candidate build-verified, needs A/B vs N64 reference before making it default. |
-| D303 | Wrong extra long muzzle flash (M16 + others) | Reported only, not investigated. |
+| D303 | Wrong extra long muzzle flash (M16 + others) | **Investigated — pipeline + data ruled out.** Flash path (`gunUpdateAndFire` → `rwmtx[1]/[2]`, `dorottex` DLPRIMARY arms) is byte-identical game code; M16's `MuzzleFlashExtension`=6.0 is the legitimate max stat; Gm16Z flash-node data byte-faithful through d43. Headless runs can't fire weapons (guards don't shoot an idle player), so a TEMP `GE_D303=1` probe in `gfx_pc.cpp` logs every very-tall-thin emitted triangle with full RDP state — **blocked on a live firing capture** (playtest brief item 17). |
 | D306/D308 | Z-fighting: Dam intro/truck wheels + general/broader instances | Two reports, likely one family; investigate together. |
 | D307 | In-level security camera props face backwards on some levels (Bunker) | **Investigated 2026-09-21 — no port-side bug found.** Full orientation path traced (`setupCctv` → per-frame `RotY(unkC8)×unk84`); every input verified N64-faithful against the ROM (PcctvZ switch data, boundpads incl. the legitimate load-time room-scale ×1.8542, record config words); all math helpers are byte-identical `src/game` code. Remaining suspect if it genuinely differs from N64: fast3d handling of the non-orthonormal lens matrix. **Blocked on user repro detail** (which camera/level + screenshot + ideally N64 compare). `GE_D307=1` diagnostic kept in-tree. |
 | D236 | Surface 1 billboard trees render as a solid wall of texture | **FIXED (M-198, pass 26, `425237f9`):** root cause was a texture-BINDING bug — `TEXTURETYPE_DETAIL` cards drawn from the detail tile (opaque IA8 noise) instead of the base image; `gfx_lod_tile_offset` now samples tile 1 when the pair differs (`Video.DetailBaseTile`, default on). Live-verified Surface 1/2 + Depot; other levels provably untouched. Awaiting user play-test sign-off; probes stripped (`0503d335`). |
@@ -301,6 +301,19 @@ Order by user-visible value:
   fast3d's handling of the non-orthonormal lens matrix (`unk84` row 0 scaled
   0.1×). Blocked on user repro detail (which camera/level + screenshot).
   Findings entry updated; probe kept in-tree (D60/D88 pattern).
+- **D303 (extra long muzzle flash) investigated — no port-side bug found yet,**
+  blocked on live capture. Mapped the full flash pipeline (`gunUpdateAndFire`
+  builds `rwmtx[1]` = yaw×scale×flashext and `rwmtx[2]` from `Switches[2]`; the
+  flare arms are `dorottex` DLPRIMARY nodes) — all byte-identical game code,
+  matrix helpers verified index-for-index. Ruled out: weapon stats (M16's
+  flashext=6.0 is the legitimate max, sniperrifle matches; the ext≥3 ⊆
+  CAN_DUAL_WIELD overlap is design coincidence) and model conversion (Gm16Z
+  DLPRIMARY records + vertex blocks byte-faithful per d43 round-trip). Added a
+  TEMP `GE_D303=1` probe in `gfx_pc.cpp` (cached-getenv; logs very-tall-thin
+  emitted triangles with blend/oml/comb/prim/env/w) — 75 s unattended runs on
+  Bunker1/Dam/Depot show only static scene geometry, so the artifact needs a
+  live firing repro. Next: user fires the M16 under `GE_D303=1` and shares the
+  log lines; the spurious quad's RDP state will identify its source.
 - **Plan/doc refresh:** D75 (M-197) and D236 (M-198) marked fixed throughout
   (Bucket A rows, Phase 1 items 6/7/11, playtest brief); findings index
   regenerated; README Known Issues to match.
@@ -354,6 +367,11 @@ Checklist beyond the normal play:
     facing backwards, note which level + which camera (screenshot) — the
     orientation math is verified N64-faithful, so a concrete repro is what's
     needed to keep chasing it.
+17. **D303 (extra long muzzle flash)**: run with `GE_D303=1` in your terminal,
+    fire the M16 (and any other gun that shows the extra upward flash) until
+    you see it, then share the `D303:` log lines from around that moment —
+    each line carries the RDP state of a candidate quad and will identify the
+    spurious draw call's source.
 
 ## Conventions reminder
 - One findings entry per investigation; next labels after **D322**.