D252: document the rainbow particle-palette bug (no fix for v0.2.0-pre)

User playtest report: bullet-impact sparks and lingering smoke/explosion
residue drift through the full hue wheel over time instead of holding their
intended grey/orange palette. Logged in findings §F (D252) with this
session's mechanism work: particle colour comes entirely from the 15
distinct IMAGE_SMOKE_N x IMAGE_FIRE_N (RGBA16) pairs the particles age
through (assets/oddtextures.c records, white default vertex); the M-82/D172
tile-offset fix and the 5551 decode are both verified correct for this path;
prime suspect is import_texture_rgba16 deriving width/height from the tile
line size (32x7 instead of 16x14 for the 16px-wide fire tiles), which would
scramble each aging stage into a different wrong hue -- exactly the observed
slow rainbow sweep. Per user instruction: documented only, ships as a known
issue (README + release notes + GRAPHICS-BACKLOG); index csv regenerated.

docs/dev/GRAPHICS-BACKLOG.md

@@ -33,6 +33,7 @@ once the game is playable start-to-finish without crashes.
 | **D182** | SELECT FILE screen degrades after navigating away and back (main menu → file select, or backing out of file select and re-entering). On the fresh screen the 007 gun-barrel spiral / Bond silhouette renders behind the file boxes; after a round-trip **the Bond image stops drawing entirely** and the whole background gains the **comb / interlacing** artifact (horizontal line scramble). File boxes, text and the Copy/Erase icons still draw. | **Observed, screenshot committed** (M-35, user QA; `docs/img/bugs/d182-file-select-backout-20260902.png`). Two symptoms, likely linked: **(1)** background 3D image stops rendering after re-entry → a front-end model/DL whose `render_pos` / segment binding is only valid on first construction (D149 / D75 `constructor_menuXX` family — the dossier/wallet models have the same "renders once" behavior). **(2)** interlacing = **M-36 triage: Family A**, the `import_texture_*` `line` vs `full_image_line` shear (see D176(b) / `docs/dev/M-36-TRIAGE.md`) — **not** the D159 `texSwapAltRowBytes` path (that is a full PORT no-op). Open question: why only *after* a round-trip — first import may land `line == width`, re-import may not, or the tile descriptor is stale on re-entry. Repro: `GE_STARTMENU` to file-select, back out with ESC/B, re-enter; `GE_DTEX` on the spiral texture across both visits. Shares defect (2) with D176(b). |
 | **D197** | Character face/head textures wrap wrong — the face texture repeats around the side of the head "and continues weird" instead of clamping to the front. Seen on **Silo** (M-49 playtest), intermittent ("sometimes"). Reads as **`G_TX_CLAMP` not honoured** for the character-skin tile in fast3d (→ `GL_REPEAT`, so the face UV region tiles around the skull), or wrong `shifts`/`shiftt` / LOD-tile selection on the head texture, or the D167 non-PoT wrap-period issue (head textures are often non-PoT) hitting skinned models. | **Observed, not investigated** (M-49, user bug report — needs a capture + which chr/level). Distinct from D176(b)/D182(2) (those are *bg wall* pitch shear). Related: RC3/D167 (`Video.WrapFix`, non-PoT wrap period) + the `texWriteTileLods` `shifts=shiftt=lod` note in findings §F "D176(b) → 4. candidate 2". First checks: does `gfx_pc.cpp` map N64 `cms/cmt` `G_TX_CLAMP` → `GL_CLAMP_TO_EDGE` for character DLs; is the head tile getting the base tile vs an LOD tile (D107); try `Video.WrapFix=1` on a repro. |
 | **D195** | Transparency / alpha-blended surfaces render wrong — reported on **Control** (Severnaya bunker basement — Natalya's console room; heavy on glass partitions and the translucent projected/holographic wall displays). Exact failure mode not yet pinned by the reporter (M-49 playtest): candidates are alpha-blended geometry drawing fully opaque, translucent panels drawing invisible, or draw-order/sort so translucent surfaces occlude what's behind. | **Observed, not investigated** (M-49, user bug report — needs a `GE_PCDUMP` capture + which surfaces). fast3d render-mode / combiner path. Same neighborhood as D161 (CI8 tile + `G_TT_NONE` → garbage), D172 (particle-sprite channel order), D176(b) (texture pitch shear) — but this is a *blend/alpha* defect, not a texture-decode one. Note D128 already touched Control's `specialportalarray` (portal struct stride) — check whether the affected surfaces are portal-adjacent. First checks: does `gfx_pc.cpp` honour `G_RM_*` XLU render modes + `G_AC_THRESHOLD`/`G_CC` alpha for these DLs; is `gDPSetRenderMode` `w1` being parsed (cf. findings §F "zbuf-clear w1 scribble"); is Z-write-vs-blend ordering right for XLU surfaces. Get the reporter to say: opaque-where-should-be-clear, invisible, or wrong edges? |
+| **D252** | Particle effects cycle through a rainbow palette — bullet-impact sparks and lingering smoke/explosion residue drift through the full hue wheel over time (~10 shots to sweep it) instead of holding their intended grey/orange palette (M-124, user playtest). Full mechanism + suspect in findings §F **D252**: colour comes from 15 distinct `IMAGE_SMOKE_N`×`IMAGE_FIRE_N` (RGBA16) pairs the particles age through; prime suspect is `import_texture_rgba16` deriving width/height from the tile line size (32×7 instead of 16×14 for the fire tiles), scrambling each stage's sprite into a different wrong hue. | **Documented only — not fixed for v0.2.0-pre** (user instruction). Confirm with one dumped fire tile vs raw `IMAGE_FIRE_N` bytes, then derive width/height from the LOADBLOCK dtx/dlh. D172/M-82 lineage. |
 | **1P weapon viewmodel** | **RESOLVED (M-83, D215).** In-level first-person weapon models drew nothing. Root cause: `gunRenderFirstPersonGunModels` built its `ModelRenderData` via `*(ModelRenderData*)&D_80035CC0` — a reinterpret across two separately-declared adjacent globals that only lands right on the N64 linker + 4-byte pointers; on x86-64 `renderdata.flags` read 0, gating every weapon DL node off in `modelRenderNodeGundl`. All 3 ranked suspects in VIEWMODEL-RESEARCH.md were ruled out first by the `GE_DVM=1` probe. Fixed `#ifdef PORT` (explicit field init). `subdraw` 1→153 gfx cmds; owed one BUNKER1 eyeball. |
 
 ## Resolved (for reference)