feat(portal): switch servers by walking or flying through portals

[TheMeinerLP]

Summary

Players can now switch servers by walking or flying (elytra) through a portal. Portals are map data: a portals list in each world's map.json, so season worlds carry their own. Two shapes are supported:

• box: axis-aligned, block-inclusive min/max
• disc: center, radius, normal, any orientation (e.g. the big leaf ring)

The target is a CloudNet task. Each portal can have an optional permission.

"portals": [
  {"id": "survival", "task": "Survival", "shape": {"type": "box", "min": {"x": 10, "y": 64, "z": 10}, "max": {"x": 14, "y": 68, "z": 11}}},
  {"id": "elytra-ring", "task": "ElytraRace", "permission": null, "shape": {"type": "disc", "center": {"x": 0.5, "y": 72, "z": 40.5}, "radius": 5.5, "normal": {"x": 0, "y": 0, "z": 1}}}
]

How

• Core types in core: PortalShape (Box, Disc), Portal, PortalValidator, LobbyPortals.
• Detection is a segment test from the old to the new position. The disc math is adapted from Voyager's RingPass, the box uses the slab method. A fast elytra step through a thin ring is therefore caught.
• A chunk-column index keeps the per-move cost to a couple of hash lookups.
• A portal triggers once on entering, followed by a 3 s cooldown after an actual delivery.
• LobbyMap.portals plus PortalGsonAdapter read and write the data. Invalid portals abort startup and name the world, the portal and the reason.
• The LobbyPortals bean is provided by runtime.
• New column features/portal (priority 900) in both the cloudnet and local variants.

Why this shape

This supersedes #222, which used an operator portals.json, Coris cuboids only, and FeatureGate / bridge ServiceAvailability from the unmerged #216. Portals belong to the world, so they live with the map. There is no reachability pre-check: CloudNet's task routing handles it, like the navigator.

Known limits

• A single move longer than ~16 blocks that meets a portal only in a middle chunk column is missed.
• Detection uses the feet point.
• Map changes need a lobby restart.

Follow-up

Setup commands (/setup portal ... with a guided flow, live preview and tab completion) come with the separate change setup-portal-command.

Tests

• DiscTest (including an 8-block elytra step over a 1-block disc), BoxTest, PortalValidatorTest
• PortalGsonAdapterTest, LobbyMapPortalsTest, MapProviderPortalTest, LobbyPortalsBeanTest
• PortalIndexTest, PortalTriggerTest, PortalModuleTest, PortalModuleLeakTest
• VariantStartTest in both apps
• ./gradlew build is green.

Not tested: a live CloudNet transfer.

OpenSpec

openspec/changes/lobby-portals

https://claude.ai/code/session_01A7aAe2E6wAEbi6jjnyPTWH

[github-actions]

Test results

  303 files    303 suites   18m 9s ⏱️
  574 tests   573 ✅ 1 💤 0 ❌
1 722 runs  1 719 ✅ 3 💤 0 ❌

Results for commit caa9c21.