Twin Emperors: rewrite tank swap, pickup anchors, and emergency split recovery

[RovxBot]

Objective

Rewrite Twin Emperors tank behavior so swap pickup, side anchoring, reserve promotion, teleport-prep geometry, Vek'nilash orientation, and emergency split recovery are phase-driven and deterministic.

Why this exists

The local logs show the encounter failing exactly where tank control should be strongest.

Observed locally:

• 493 split_risk entries, all with reason=tank_swap_failure.
• Separation starts failing at 61 and drops as low as 17.
• Heal Brother is repeatedly firing instead of being prevented:

17:00:00.504 SPELL_HEAL Emperor Vek'lor -> Emperor Vek'nilash "Heal Brother"
17:00:00.512 SPELL_HEAL Emperor Vek'nilash -> Emperor Vek'lor "Heal Brother"
17:00:56.309 SPELL_HEAL Emperor Vek'lor -> Emperor Vek'nilash "Heal Brother"

• Tank mechanics are happening during the collapse:

17:00:00.512 SPELL_DAMAGE Emperor Vek'nilash -> Rov "Uppercut"

• Current fallback behavior still allows ad hoc range-chasing and MoveNear recovery instead of a strict anchor plan.

Current code hotspots

• src/Ai/Raid/Aq40/Action/RaidAq40Actions_TwinEmperors.cpp
  • ResolveTwinPickupAnchor
  • Aq40TwinEmperorsHoldSplitAction
  • Aq40TwinEmperorsWarlockTankAction
  • StopTwinDamageOn
  • GetFarSidePosition
  • GetTwinRecoveryStepTowardAnchor
• src/Ai/Raid/Aq40/Util/RaidAq40TwinEmperors.cpp
  • melee recovery timers
  • pickup anchor locking
  • kTwinTeleportWindowMs = 6000
• src/Ai/Raid/Aq40/Util/RaidAq40Helpers.cpp
  • tank executor / reserve resolution
• Current warlock pickup geometry already uses:
  • desiredRange = 24.0f
  • minRange = 19.0f
  • maxRange = 30.0f
    but it is still too reactive and does not encode the intended pre-teleport ordering strongly enough.

Required implementation

• Make both tank roles explicitly phase-driven.
• During TeleportWindow and PickupRecovery:
  • primary warlock and primary melee tank must move to forced pickup anchors first
  • threat generation or melee uptime starts only after the anchor step is satisfied or a clearly defined “in-position enough” rule is met
• Define reserve behavior explicitly:
  • reserve tanks stay parked and do not improvise
  • reserves are promoted only by encounter state, not by incidental aggro
• Add an encounter-wide emergency split recovery routine:
  • trigger when separation enters urgent/terminal bands or Heal Brother fires
  • stop raid DPS on both bosses
  • stop pets
  • clear unsafe current targets
  • force both tanks through re-separation routing until the split is stable again
• Replace MoveNear as the primary tank recovery behavior. MoveNear should only survive as a last-resort fallback with logging that makes it obvious it was reached.
• Tie Uppercut / Unbalancing Strike recovery directly into the tank state machine so recovery windows are explicit and compatible with emergency split recovery.
• Keep primary tank movement owner-exclusive while the tank is in a recovery phase.

Additional tank-positioning requirements

Vek'nilash side orientation

• The Vek'nilash tank should face the boss toward the wall so Uppercut knockbacks send melee toward the room center instead of deeper into unsafe geometry.
• This facing/orientation rule should be part of the tank positioning contract, not an incidental side effect.
• If exact facing control is difficult, at minimum the selected tank anchor family should make the likely Uppercut vector center-safe.

Vek'lor receiving side

• Shortly before teleport resolves, the designated warlock tank on the receiving side must move inward toward the melee tank.
• The goal is that when Vek'lor arrives, the warlock is the second closest valid unit and can immediately cast Searing Pain.
• This movement must happen before Vek'lor arrives, not only after the swap has already completed.
• Backup warlocks must stay parked and must not drift into the receiving geometry.

Vek'nilash receiving side

• Shortly before teleport resolves, the designated melee tank on the receiving side must move inward so they are the closest valid unit when Vek'nilash arrives.
• That inward movement must still respect Vek'lor's Arcane Burst safety rules.
• Do not let the melee receiving tank solve this by simply standing too deep and eating Vek'lor danger range.

Implementation guidance

• Encode these as named Twin geometry rules or phase-specific anchor families instead of relying on generic “approach until in range” behavior.
• If current hardcoded distances (24/19/30) are kept, wrap them in named constants that explain their role in teleport-prep geometry.
• If better geometry is found during implementation, keep the relative ordering contract:
  • receiving melee tank is closest for Vek'nilash
  • receiving warlock tank is second closest for Vek'lor
  • Vek'lor safety band is still respected

Reference patterns

• PR #2363: ICC V2, Autogear BiS cmd mod-playerbots/mod-playerbots#2363
  • Repeatedly uses explicit tank handoff logic, encounter-specific movement ownership, and deterministic boss positioning.
• Sunwell Eredar Twins actions:
  • https://github.com/brighton-chi/mod-playerbots/blob/the-lab/src/Ai/Raid/SunwellPlateau/Action/RaidSunwellEredarTwinsActions.cpp
  • Useful examples: fixed tank positions, step-based relocation, and threat-hold style behavior that prevents unsafe DPS during unstable states.

Validation

• Run at least 3 teleports with a supported Twin comp.
• Success criteria:
  • no split_risk
  • no heal_brother_terminal
  • tanks re-establish both sides before ranged DPS resumes on Vek’lor
  • primary tanks do not drift into MoveNear as the normal recovery path
  • receiving warlock is staged for immediate Searing Pain on Vek'lor arrival
  • receiving melee tank is closest for Vek'nilash arrival without violating Vek'lor safety spacing
  • Vek'nilash tank orientation keeps Uppercut knockback center-safe
• Additional test:
  • induce Uppercut / Unbalancing Strike pressure and confirm tanks recover without collapsing the split

Related

• Depends on #2 phase and ownership work.
• Coordinate with #6 so spell-driven events can trigger recovery at the right time.
• Coordinate with #8 for the broader pre-pull / opener choreography.