docs: file #419 — tunnel rim polygon + exit ring flash, decomp-anchored (fixed CreatureMode camera 0.24/-2.7/0.88, view-plane exit)

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

docs/ISSUES.md

@@ -24,6 +24,35 @@ What does NOT go here:
 - Every session: scan OPEN issues at start; promote/close anything we touched during the session before ending.
 - Promoting to a Phase: mark as `DONE (promoted to Phase X)` + commit SHA where the Phase entry landed.
 
+## #419 — Portal-tunnel rim polygon visible (FOV-coupled) + ring flash at exit (camera dolly vs retail's view-plane animation)
+
+**Status:** OPEN (filed 2026-08-17, user screenshot + FOV experiment).
+**Symptom:** the tunnel's low-poly mouth shows as a faceted polygon
+silhouette against black, scaling with the Config FOV slider (barely
+visible at minimum FOV); a brief ring flash remains at exit even at
+minimum FOV. **Decomp truth (`gmSmartBoxUI::UseTime @0x004D6F34`):**
+retail renders portal space as a CreatureMode UI VIEWPORT with its OWN
+projection — NOT the game camera. On tunnel entry it starts the 40 fps
+authored animation (`set_sequence_animation`, DID via GetDIDByEnum
+`0x10000002` slot 7) and parks the viewport camera at the authored point
+**(0.24, −2.7, 0.88)** (`CreatureMode::SetCameraPosition`, constants
+`0x3e75c28f/0xc02ccccd/0x3f6147ae`); the swirl's drift is a randomized
+roll via `CreatureMode::SetCameraDirection_Degrees` (angle/duration
+random-walk block @0x004d6fd0, beside the "In Portal Space - Please
+Wait..." notice). The exit "zoom" is NOT a camera move: `TUNNEL_FADE_OUT`
+@0x004d713b animates the transition view PLANE's distance
+(`TRANSITION_VIEW_PLANE_DISTANCE` / `TELEPORT_ANIM_FADE_TIME`
+constants) with the camera parked. **Our defect:** the portal viewport
+draws with `_camera.Active.Projection` (game FOV + display aspect —
+`LocalPlayerPortalViewport.Draw` in PrivatePresentationRenderer.cs), so
+a wide FOV/aspect reveals the tube mouth retail's fixed frustum clips;
+and if our exit moves the camera, the mouth sweeps through view once
+(the min-FOV flash). **Fix shape:** authored fixed camera + viewport
+projection for the tunnel pass (find CreatureMode's projection
+parameters in the viewport render setup), port the roll drift, express
+the exit as the view-plane distance animation. Retail-faithfulness fix —
+no tuning knobs.
+
 ## #418 — Login world load takes ~27 s: publication advances at a flat 32 blocks/s
 
 **Status:** IN-PROGRESS 2026-08-17 — producer half landed (this commit's