fix #176 #177: the camera-capped light snapshot evicted visible cells' torches — per-cell lighting popped at seams

The probe launch discriminated it: the user reproduced the purple floor
flash while [light] (ambient branch) and [pv-input] (portal flood) read
provably healthy — eliminating the last CPU-side theories and exposing
the one channel the probes could not see: per-cell 8-light set
composition.

BuildPointLightSnapshot kept the MaxGlobalLights=128 point lights
nearest THE CAMERA; the Facility Hub registers 366 fixtures, so 238
were evicted per frame by camera distance. SelectForObject (faithfully
camera-independent, and unit-pinned as such) could only choose from the
surviving 128 — an in-range torch of a visible cell that ranked past
the cap dropped out of that cell's 8-set, so per-cell Gouraud lighting
flipped as the chase boom swung the camera:

- #176: the flipping unit is a CELL -> discontinuity lines at exactly
  cell-seam granularity; a torch-losing floor drops to dim blue-grey
  stone at 0.2 ambient (the perceived purple), camera-angle dependent.
- #177: a stair room whose torches all ranked past the cap rendered at
  bare 0.2 ambient (near-black = 'not visible'); approach re-admitted
  them ('pops into existence'); the sweeping boundary dropped the
  ramp's lights mid-descent ('disappears on the last step'). The
  geometry never vanished - its lights did.

Retail's minimize_object_lighting (0x0054d480) has NO global
camera-nearest pool cap (lights register per cell, insert_light
0x0054d1b0). Fix: MaxGlobalLights 128 -> 1024, a non-biting safety
valve (GlobalLightPacker grows to fit; 64 B/light). Register row AP-85.

TDD pin: PointSnapshot_HubScaleLightCount_ObjectSelectionIsCameraInvariant
(RED at 128 with a Hub-scale 401-light layout, GREEN at 1024). The
pre-existing camera-independence pin covered the SELECTOR but not the
SNAPSHOT it selects from - the pop re-entered one stage upstream.

Suites: Core 2588 / App 719 / UI 425 / Net 385 green. Pending user gate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/ISSUES.md

@@ -106,18 +106,23 @@ corridor, and (c) pops into existence on entering the room. Classic
 portal-visibility miss: the stair geometry's cell is not reached by the
 portal flood from the viewer's cell until the viewer crosses into it.
 
-**Root cause / status:** INVESTIGATED 2026-07-06 (session 2) — the #119
-class is REFUTED for this issue: the "stairs" are a RAMP owned by shell
-cell 0x8A020182 (no statics anywhere near), connected by VERTICAL portals
-(not floor-portals), and the portal flood admits 0x0182/0x0183 correctly
-from every tested corridor eye/pitch (headless replays
-`Issue176177FacilityHubFloodReplayTests`). Membership transits are
-plane-exact; mesh/frustum/texture layers verified healthy. Twelve
-candidate mechanisms refuted — full ledger + the surviving theories +
-the ONE-launch probe protocol in
+**Status update:** 🟡 FIX SHIPPED 2026-07-06 — pending user gate.
+**Root cause (found via the probe launch):** the geometry never vanished —
+its LIGHTS did. `BuildPointLightSnapshot` kept only the `MaxGlobalLights=128`
+point lights nearest THE CAMERA; the Facility Hub registers 366 fixtures, so
+238 were evicted per frame by camera distance. A room whose torches all
+ranked past the cap rendered at bare 0.2 ambient (near-black in a dungeon =
+"not visible"); approaching re-admitted them ("pops into existence"); the
+eviction boundary sweeping with the camera dropped the ramp's lights
+mid-descent ("disappears on the last step"). Retail's
+`minimize_object_lighting` (0x0054d480) has no global camera-nearest cap.
+**FIX:** cap raised to a non-biting 1024 safety valve (register row AP-85);
+pin `LightManagerTests.PointSnapshot_HubScaleLightCount_ObjectSelectionIsCameraInvariant`
+(RED at 128, GREEN at 1024). Investigation ledger (12 refuted mechanisms +
+the probe run that discriminated):
 `docs/research/2026-07-06-176-177-render-pair-investigation.md`.
-NEXT: run the probe protocol (ACDREAM_PROBE_LIGHT + ACDREAM_PROBE_PVINPUT
-+ ACDREAM_PROBE_CELL) during the pending #175 door-gate launch.
+**Gate:** stairs/stair room stay visible (lit) from the corridor, through
+the descent, at all approach angles.
 
 **Acceptance:** the staircase renders whenever its room is visible through
 the connecting opening, and stays rendered through the full descent.
@@ -138,20 +143,25 @@ render; the physics fix landed (seam shake gone, user-gated) and the flash
 REMAINS — so it is a render-side issue in its own right, correlated with
 camera angle.
 
-**Root cause / status:** INVESTIGATED 2026-07-06 (session 2) — the
-placeholder-texture theory is REFUTED (all surfaces resolve; the floor
-IS drawn: the textured PortalSide floor-portal strips are included by
-CellMesh.Build; the under-hall reciprocal is NoPos). So are eleven other
-mechanisms (seal z-fight, root/eye incoherence, flood bistability, DXT
-alpha/undefined mips, fog mix, lightning leak, viewer-light pops…) —
-full refutation ledger, the two surviving theories (T-A outdoor-ambient
-flip on playerRoot gaps: sun-on-floors explains the FLOOR selectivity;
-T-B flood misbehavior under real production inputs), and the ONE-launch
-probe protocol in
+**Status update:** 🟡 FIX SHIPPED 2026-07-06 — pending user gate.
+**Root cause (found via the probe launch):** per-cell LIGHTING pops, not a
+draw failure. The probe run reproduced the flash while the ambient branch
+([light] insideCell/0.2 grey — stable) and the portal flood ([pv-input] —
+zero drops in 54k frames) were provably healthy — which eliminated the
+last CPU-side theories and exposed the one channel the probes could not
+see: per-cell 8-light SET COMPOSITION. `BuildPointLightSnapshot` kept the
+128 lights nearest THE CAMERA of the Hub's 366 registered fixtures; an
+in-range torch of a visible cell that ranked past the cap was evicted, so
+that CELL's Gouraud lighting flipped as the camera moved — discontinuity
+lines at exactly cell-seam granularity, camera-angle dependent (the chase
+boom swings the camera position, re-ranking the 128), and a torch-losing
+floor drops to dim blue-grey stone (the perceived purple flash). Twelve
+other mechanisms refuted first — ledger in
 `docs/research/2026-07-06-176-177-render-pair-investigation.md`.
-The purple itself can only be the fog-tinted clear color (undrawn
-pixels) or the outdoor ambient+sun tint — every other purple source in
-the pipeline is now excluded. NEXT: the probe launch (see #177).
+**FIX:** `MaxGlobalLights` 128 → 1024 non-biting safety valve (AP-85);
+pin `LightManagerTests.PointSnapshot_HubScaleLightCount_ObjectSelectionIsCameraInvariant`.
+**Gate:** no purple/lighting flashes on floors at corridor seams from any
+camera angle while running the 015E↔017A loop.
 
 **Acceptance:** no purple/placeholder flashes on dungeon floors from any
 camera angle at the corridor seams.