fix(visibility): enforce the role visibility matrix between all three roles

[TheMeinerLP]

Target matrix

Who (row) may see whom (column) as an entity:

Viewer	Slender	Survivor	Spectator
Slender	–	yes	never
Survivor	only while revealed	yes	never
Spectator	same as the survivor view	yes	yes

Chat: survivor and slender messages reach everyone, spectator chat stays among spectators — in every phase.

Root cause

Visibility was driven by two competing mechanisms at the same time: Minestom's viewable rule and manual viewer packets (updateNewViewer / updateOldViewer). The latter are purely packet based and never touch the viewer bitSet of the EntityView, so the two layers drifted apart:

• GameStartListener hid the slender via updateOldViewer without deregistering anyone. The next rule evaluation saw isRegistered == true and skipped the spawn packet.
• The manual toggle sent updateNewViewer first and re-evaluated the rule afterwards → duplicated spawn packets.
• The automatic transition once the bar ran dry went through the manual layer only and was silently reverted by the next rule evaluation.

This change unifies everything onto one layer: per-viewer predicates exclusively, collected in the new VisibilityRules class.

Verified against Minestom 2026.07.22-26.2 (EntityView.java): the predicate receives the viewer and is evaluated whenever somebody enters range, so the matrix is natively expressible. addViewer / removeViewer stay unused on purpose, since they record players in manualViewers and would disable the rule for them permanently.

Violations fixed

Finding	Before
Spectators could not see each other	updateViewableRule(_ -> false)
Revived slender permanently visible	the revive set neither the rule nor Tags.HIDDEN
Slender visible between team allocation and game start	the rule was installed before Tags.HIDDEN existed
Spectator chat leaked to everyone	fail-open: null instanceof GamePhase == false, plus a gap during the restart phase
Spectators took slender damage	setHealth without a team/game mode filter — a dying spectator then triggered a second death message and a second SpectatorAddEvent
Spectators heard the teleport sound	exactly when the slender turned invisible, no role filter
Slender and spectators received jumpscares	including DARKNESS for 40 ticks on the slender

Cleanup

• ViewRuleUpdater removed: isViewAble was dead code with an inverted name; isHidden and updateViewer were absorbed into VisibilityRules.
• SlenderBarTrigger loses updateRuneFunction, PlayerChatListener loses phaseSupplier — both only fed the paths that are gone now.
• The metadata broadcast to all players is dropped; Minestom pushes metadata to the entity's viewers anyway, and switchEntityType respawns on its own.

Tests

./gradlew build is green across all modules. One test per matrix cell plus regression tests:

• VisibilityRulesTest — all six cells
• SpectatorServiceTest — testJoinMakesPlayerInvisibleToOthers cemented the old bug and was replaced
• SlenderReviveIntegrationTest.testRevivedSlenderIsHiddenFromEveryoneElse
• PlayerChatListenerTest — game phase, restart phase and without an active phase
• SlenderBarHelperTest, CygnusPlayerTickListenerTest

SlenderBarIntegrationTest.testAutoDepletionPlaysTeleportSound had to be adjusted: its own comment says "plays to nearby survivors", but it never tagged the player as a survivor and only passed because there was no role filter at all.

Deliberately out of scope

Fully documented in docs/plans/role-visibility-matrix.md. The largest remaining leak:

TeamHelper.updateTabList gives the slender the display name ⛧ name in red. This is broadcast to everyone via UPDATE_DISPLAY_NAME — every survivor and spectator immediately sees who the slender is in the tab list, and the same name sits under every chat message they send. Possibly intentional, so it is left untouched here.

Also open: page discoveries and death messages are broadcast unfiltered (real-time information for the slender); the corpse mannequin's particles bypass every viewable rule through sendGroupedPacket; finishGame resets no rules (harmless today, since one process serves exactly one round, but relevant as soon as a round reset is introduced).

Follow-up from the implementation: stamina → team is now a package cycle, because TeamHelper reads the HIDDEN constant from SlenderBarHelper. Moving VISIBLE / HIDDEN into a neutral holder would resolve it.

🤖 Generated with Claude Code

https://claude.ai/code/session_01QQCb6kSTw5NnRF1Yc4hYXg

[github-actions]

Test results

249 files  249 suites   1m 50s ⏱️
306 tests 301 ✅  5 💤 0 ❌
921 runs  906 ✅ 15 💤 0 ❌

Results for commit 9321c37.