diag(D172): rule out cycle-type too; ship GE_D172 probes

Real particle records (assets/oddtextures.c globalDL_0x078..) DO set
gsDPSetCycleType(G_CYC_2CYCLE); GE_D172=1 probe confirms fast3d applies it
(particle combine fc26a004 logged at cycletype=2CYC). Both the 0xB9-abort
and the cycle-type hypotheses are now dead. Bug is the G_CC_INTERFERENCE
two-tile combine / TEXEL1 path (IA8 smoke x RGBA16 fire @ tmem 0x188).

Probes (#ifdef PORT, GE_D172=1, inert otherwise):
- gfx_pc.cpp G_SETCOMBINE: distinct combine + active cycletype
- gfx_pc.cpp gfx_sp_tri1: tris with cyc2 combine drawn at cycletype!=2CYC

Needs a display capture to go further (headless can't see particle colour).

docs/dev/GRAPHICS-BACKLOG.md

@@ -18,7 +18,7 @@ once the game is playable start-to-finish without crashes.
 | **D149** | Front-end MISSION COMPLETE / mode-select 3D models (dossier, wallets) render as garbled full-screen geometry or not at all — one of the compiled sub-DLs (seg5+0x9ee4) is malformed, D146 now skips it instead of aborting. | D75 family. §F D146. |
 | **D170** | Named-NPC "flee" scripted behavior looks wrong on PC: on Silo, Ourumov breaks into a full run the instant he alerts ("Ourumov: Kill him!") rather than the N64 walk/retreat; developer reports Trevelyan behaves the same way on Cradle. **M-49 full playthrough: escalated — Cradle (`-level_51`) is "bugged out completely" from Trevelyan's behavior; the final level's scripted progression breaks. Now folded into / superseded by §F D193 (NPC AI locomotion too slow).** | **Observed, not investigated** (M-34, from a Silo playtest capture; user bug report — no fix wanted yet). Could be a genuine ailist / `chrTick` divergence, OR the D155/D156 wall-clock `deltaFrames` locomotion-anim speed-up (a catch-up spike playing the walk cycle at 2–3×). **Verify first:** capture the same beat against N64 reference footage before assuming it diverges — Ourumov may be scripted to flee. If it's real, suspect the frametiming clamp (§F D155/D156) or the Cradle-family AI path (§F D123). |
 | **D171** | Silo missile-shaft: a large translucent grey triangle sweeps across the lower frame while panning down the shaft (~3 s of the capture). Looks like a stray poly / near-plane clip fan, same family as D106 (portal near-plane min>max). | **Observed, not investigated** (M-34, Silo capture). Cosmetic, intermittent, tied to camera angle in the open vertical shaft. |
-| **D172** | Bullet-impact / blood particle spray renders magenta or cyan instead of dark red (visible on guards hit at close range on Silo). | **M-82: 0xB9 root cause WITHDRAWN** (`docs/dev/D172-PARTICLE-COLOR-RESEARCH.md` §4). 0xB9 = `G_SETOTHERMODE_L` in this non-F3DEX2 build (`= G_IMMFIRST-6`), already handled by fast3d as `gsDPSetRenderMode`; `-level_09` sustained-fire run logged **zero D146 aborts**. New primary hypothesis: the dominant particle combine is **2-cycle** but the records never set `G_MDSFT_CYCLETYPE`, so on PC `use_2cyc==0` → only cycle-0 runs → TEXEL1 garbage → magenta/cyan. Next: env-gated `use_2cyc`/CC-key probe on particle tris; fix = emit explicit `gsDPSetCycleType(G_CYC_2CYCLE)` in `explosion.c` under `#ifdef PORT`. |
+| **D172** | Bullet-impact / blood particle spray renders magenta or cyan instead of dark red (visible on guards hit at close range on Silo). | **M-82: 0xB9 root cause WITHDRAWN** (`docs/dev/D172-PARTICLE-COLOR-RESEARCH.md` §4). 0xB9 = `G_SETOTHERMODE_L` in this non-F3DEX2 build (`= G_IMMFIRST-6`), already handled by fast3d as `gsDPSetRenderMode`; `-level_09` sustained-fire run logged **zero D146 aborts**. **Cycle-type also ruled out (M-82):** the real records (`assets/oddtextures.c` `globalDL_0x078…`) *do* `gsDPSetCycleType(G_CYC_2CYCLE)`, and a `GE_D172=1` probe confirms fast3d applies it (particle combine `fc26a004` logged at `cycletype=2CYC`). Bug is the **`G_CC_INTERFERENCE` two-tile combine / TEXEL1 path** — record binds tile 0 (IA8 smoke) × tile 1 (RGBA16 fire @ tmem 0x188); magenta/cyan = TEXEL1 tmem-offset / RGBA16 decode / LOD-tile fault. Needs a display capture. Probes shipped (`GE_D172=1`, inert). Detail: `D172-PARTICLE-COLOR-RESEARCH.md` §5–6. |
 | **D178** | Objectives not listed correctly on the pre-mission briefing screen (the mission overview shown before starting a level). | **M-36 triage: the objective lines are BLANK, not wrong.** `GE_STARTMENU=10` Dam briefing renders the header fine ("OHMSS / Agent: James Bond / Mission 1: Arkangelsk / Part i: Dam / PRIMARY OBJECTIVES:") then just the bullet "a." with no text and no b/c/d. → **D143/D151 blank-text family** (`langGet()` → NULL → silent blank), *not* a propDef walk / difficulty decode. **Family B** in `docs/dev/M-36-TRIAGE.md` — find which lang bank the front-end briefing flow fails to load. Re-confirm the exact shape in a *real* briefing (the `GE_STARTMENU` boot skips real save state). Close relatives: D151 (watch objective text blank — type-35/23 `text` slot u16→u32 fix, M-28; interactive re-verify was still pending), D143 (briefing/objective text blank via `langGet` NULL), D157 (objective difficulty byte offset — could make difficulty-gated objectives appear/disappear wrongly). The pre-start briefing is a *different surface* from the in-level watch, so D151's fix may not cover it. **Next:** ask user which level + what exactly shows vs expected; compare against `docs/dev/LEVEL-OBJECTIVES.md` (regenerated post-D157); if lines are blank → D143/D151 family (`langGet` NULL guard = silent blank), if wrong objectives listed → propDef type-23 record walk / difficulty decode. |
 | **D175** | In-game stutter / brief hang during normal play — observed opening a door on Runway (mission 3, `-level_35`) and also on Surface. No backtrace captured (gdb attach missed the window; it self-recovered). | **Observed, not investigated** (user QA report). Matches known transient-hang classes rather than looking new: D155 (post-slow-load catch-up spiral — clamped), D156 (anim NaN loop — guarded, prints one-shot stderr diag if it fires), D134 (SP/DP task-done event swallowed — fixed M-22, Runway was an original victim), D147/D152 (audio `s_imLock` steal = ~2 s hiccup). Door-open specifically = new room first visible → one-off texture-import/frame spike (likely benign). **Next:** reproduce under `tools_pc/debug.ps1` with the box idle; check console for the D156 stderr diag; if it recurs, attach gdb mid-hang and pattern-match `bt` (import_texture = benign slow frame; model.c:3131 spin = D156; pthread_mutex_lock on s_imLock = D147/D152). |
 | **D176** | Surface exterior renders wrong (two co-located defects). **(a)** Sky is solid **black** — the skybox / sky gradient does not draw at all (reference: warm sunset cloud gradient). **(b)** The perimeter **tree-line backdrop renders as grey TV-static / comb interlacing** instead of snow-laden pines — the geometry is present and roughly the right silhouette but every tree texture is scrambled noise. Ground, tunnel and the dish/bunker building draw fine. | **Observed, screenshots committed** (M-35, user QA; `docs/img/bugs/d176-surface-exterior-our-build.png` vs `-reference.png`). Level is the shared Surface exterior — user reached it Dam→Surface on Agent so this is **Surface (i) `-level_36`** (confirm it also affects `-level_43`). **(a)** black sky: **M-36 partial (findings.md "D176(a)").** Env data is correct (`Sky.Clouds=1`, `CloudRGB=240,120,30`, `SkyImageId=0`); `skyRender` runs the cloud path and classifies corners correctly (switch case 12), but `skyRenderTri`/`skyRenderFull` emit nothing — not even the `env->RGB` fill shows. Not root-caused: next is probing `sub_GAME_7F097388` projected coords, verifying `skywaterimages[0]` resolves on PC (`image_bank.c` GIMG offset `0xFB4`), and a fast3d sky-tri trace. `GE_D176=1` probe shipped. **M-37: ROOT-CAUSED** — `skyRenderTri`/`skyRenderFull` build geometry *exclusively* as `G_RDPHALF_*` immediates, which `gfx_pc.cpp` deliberately no-ops (identical no-op in the PD port); fix = decode the RDPHALF tri-raster stream in fast3d (~1 session, genuine new code). **M-42: `-level_22` (Statue) confirmed a clean headless repro** — bare boot, frame ~360, upper half pure black; use it to verify the decoder. **M-47 + read-only consolidation:** Path B draft exists (`scratchpad/sky.patch`, `skyPortRenderPoly` PORT hook — geometry+texture reach GL, two unit defects open) and the full RDPHALF wire format is now decoded (S15.1 half-packing, 8-component perspective-interpolated vertex vectors); next session is mechanical per `docs/dev/D176a-SKY-NOTES.md`. `-level_36`/`-43` intro cams face down (not a sky test without `GE_INPUTSCRIPT`). **M-82: PR #18 rebased onto main + Defect-1 fix applied** — cloud tile is `s_skywaterimages[0]` = 64×64 IA8; the patch's `tc = S·32` scale is correct (matches GE's `width<<5` idiom, `glass2.c:678`), the bug was `(s16)` overflow on the ±20k-texel horizon S/T; fix = per-primitive phase-fold to the 64-texel period (`sky.c` `skyPortRenderPoly`, `#ifdef PORT`). Builds clean, no crash (bunker1/statue/surface1 verify PASS). **Unverified visually** — owed: one `-level_22` screenshot (see `D176a-SKY-NOTES.md` "verification ask"). Defect 2 (horizon-band coverage / straddling tris) still open → adaptive tessellation. **(b)** tree/rock static: **M-36 triage — NOT the D159 family.** `texSwapAltRowBytes` is a full `#ifdef PORT` no-op (`image.c:2199`), it cannot cause this. Real cause: `port/fast3d/gfx_pc.cpp` `import_texture_*` assume `line_size_bytes == full_image_line_size_bytes` (`SUPPORT_CHECK`; rgba16's is commented out *"trips ... with a garbage size"* `:658`) → non-PoT / sub-rect tiles get a flat linear read → diagonal row shear = grey static. **Family A** in `docs/dev/M-36-TRIAGE.md`. Fix: honour `line_size_bytes` as the real source pitch. Same defect as D182(2). |