docs(issues): #464 — retail capture eliminates admission; the divergence is in the punch/seal machinery at the stairwell's open face

Retail admits exactly acdream's cells and building-portal groups in the
same order; its alpha-depth frame punches each portal polygon to far depth
right before that group's cells and seals the exit views last. The
capture becomes S4-c1's fifth transcript pose.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

docs/ISSUES.md

@@ -111,6 +111,8 @@ then `/teleloc F4180113 39.502899 19.589222 181.119247 1 0 0 0`, zoom out, tilt
 
 **Owner's TILTED frame with the transcript (2026-09-03 22:17, owner client armed by the lead with `ACDREAM_DUMP_WALK_TRANSCRIPT=1` + both probes; log `logs/launch-464-transcript-20260903-221619.log`, the frame saved as `docs/research/2026-09-01-overhaul/464-owner-tilted-frame.walk.txt`):** `/loc` player `(39.50,20.08,180.78)`, eye `(39.76,17.51,182.31)` (2.60 m back, uncontacted), root `0xF4180114`. Walk: `P f4180114`, `DI f4180114`, interior `DC pv=0 ov=7 n=3: f4180114 f4180113 f4180112` (SEVEN outside views — the default camera at the same spot had six; the tilt brings one more exit of the open face into view), then thirteen `BLD` turns whose outside pass (`pv=1`) draws sixteen building-portal groups — `f3180105`, `f4180102`, `f4180101/f4180100` ×3, `f4180103/f4180105`, `f4180104` ×3, and under building `f418000a` the hall: `f4180109`, `f4180109 f4180108 f418010e f418010b`, `f4180109`, `f4180108 f4180107`, `f4180108 f4180107 f418010f f4180110 f4180106`, `f4180107`, `f4180107 f418010f f4180110 f4180106` — and the interior repaint `EC f4180112 f4180113 f4180114` LAST. The admission set is the SAME as the default frame's; the tilt only adds the seventh exit view. So what differs on screen is not which cells draw but what the open face shows: through `0x114`'s exit portals (the far face is portal polygons only, `emitPos=False emitNeg=False`, nothing of the cell itself is drawn there) acdream shows the hall's INTERIOR cells drawn in the outside pass, while retail shows the hall's EXTERIOR wall — building-shell geometry of the outside pass — solid above the arch. **Narrowed: the building shell versus interior-cell order/clip at that face in the outside pass (which of the cathedral's building portals retail admits from an exit view, and whether the shell's wall occludes the hall cells), S4 depth/alpha with a possible building-portal admission component.** The `cathedral-stair-arch` retail capture (walk + alphadepth at this pose) decides it: retail's `DC` groups under the cathedral's `BLD` turn versus ours, and its `PM`/`FL` order at the seven exit views.
 
+**RETAIL CAPTURE `cathedral-stair-arch` (2026-09-03 23:0x, owner in the paired 2013 client at the pose, tilted as in the screenshot; `docs/research/2026-09-01-overhaul/oh-capture/cathedral-stair-arch.walk.log` + `.alphadepth.log`, 5 frames each, commit `4f12cd06b`; retail screenshot posted in chat: the far face above the arch is SOLID, a doorway with sky shows only through the arch):** retail eye `(39.58,16.99,182.79)`, root `f4180114`. **Walk: retail admits EXACTLY our set** — `DI f4180114`, `DC ov=7 n=3: f4180114 f4180113 f4180112`, eleven `BLD` turns, and under `BLD f418000a` the same seven hall groups in the same order (`f4180109`; `f4180109 f4180108 f418010e f418010b`; `f4180109`; `f4180108 f4180107`; `f4180108 f4180107 f418010f f4180110 f4180106`; `f4180107`; `f4180107 f418010f f4180110 f4180106`), interior repaint `112 113 114` last. Only differences: acdream also turns the neighbouring blocks' `BLD f3170034`, `BLD f317003d` and draws `f3180105` (retail does not — a block-admission difference, unrelated to the artifact), and retail draws `f4180104` four times to our three. **Admission is eliminated as the cause.** **Alpha-depth: retail's frame is `PC ov=7 counter=0008 fc=0`, then for each building-portal group a `PM mode=1` FAR-DEPTH PUNCH of the portal polygon immediately BEFORE that group's `PC ov=0` cell draw (sixteen punches: `12980fd4`, `12981004`×3, `1cc24bd4`, `1cc24c34`×4, `4dbb5e2c`, `4dbb5dcc`, `4dbb5dfc`, `4dbb5d6c`, `4dbb5e5c`, `4dbb5d3c`, `4dbb5d9c`), then eight `PM mode=0` true-depth SEALS with `counterBefore` 0..7 (the exit views), `FL` by site 1029/11/1/1; 249 `AM` lines, all `clip=0`.** So in retail the hall can appear only inside the punched doorway outlines; the building shell's depth hides it everywhere else, including above the arch. Acdream lets it show above the arch, so the divergence is one of: the punch fans wider than the portal outline there (AD-17's unclipped fallback for a >8-edge or multi-polygon outside view), the punch/seal ORDER against the cells, or the shell's depth missing at that face. **This capture is the fifth pose of S4-c1's PM/PC transcript gate; running that gate names the divergence line by line. The fix contract follows from it (S4).**
+
 ## #463 — Soak `turn` samples can report a 0.1 ms GPU p50 (the turn window catches non-world frames)
 
 **Status:** OPEN — found 2026-09-03 by the Campaign OVERHAUL v2 S3 review's perf re-measure.