Proposed fix drop zen in party

[nolt]

Party Zen Drop Fix

Problem

When a player killed a monster in a party, the zen (money) drop amount was
dramatically lower than when playing solo. With a high experience rate server,
a solo player could get ~1,000,000 zen per kill, while a party member would
only see ~3,000 zen. Additionally, the zen was not shared among party members.

Root Cause

The zen drop amount is calculated as gainedExperience + BaseMoneyDrop (7) in
DefaultDropGenerator.GenerateItemDropOrMoney. The gainedExperience value
comes from AttackableNpcBase.OnDeathAsync, which uses different formulas for
solo and party play:

Solo: player.AddExpAfterKillAsync()
→ baseExp * gameRate * personalRate * mapMultiplier * random

Party: party.DistributeExperienceAfterKillAsync()
→ baseExp * count * 1.05^(count-1) * mapMultiplier * random

The party formula does NOT include the game rate (e.g. 100x) or personal
experience rate bonuses, making the zen amount orders of magnitude smaller.

Changes

Three files modified on branch zen-drop-party-fix:

1. src/GameLogic/Player.cs — new CalculateExpAfterKill() method
   Extracts the experience calculation logic from AddExpAfterKillAsync into
   a separate public method that returns the calculated value without applying
   it to the character. AddExpAfterKillAsync now calls this shared method.
   This avoids duplicating the experience formula when it's needed for other
   purposes (like zen calculation).

2. src/GameLogic/NPC/AttackableNpcBase.cs — DropItemAsync()
   When the killer is in a party, uses player.CalculateExpAfterKill(this)
   to get the correct experience value for zen calculation instead of using
   the party-distributed value (which lacks game rate and personal bonuses).
   Also uses null-conditional access for Attributes instead of !.

3. src/GameLogic/DroppedMoney.cs — TryPickUpByAsync()
   When a player in a party picks up money from the ground, it is now
   distributed equally among all eligible party members (same map, not in
   safezone). Solo pickup behavior is unchanged.

Result

• Solo: 1,000,000 zen drops on the ground → picked up by one player → gets 1,000,000
• Party of 2: 1,000,000 zen drops on the ground → picked up → each gets 500,000
• Party of 5: 1,000,000 zen drops on the ground → picked up → each gets 200,000

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses a discrepancy in zen (money) drops between solo and party play. Previously, party members received significantly less money because the experience calculation used for drops excluded server-side experience rates. The changes normalize the experience calculation for money drops regardless of party status and introduce a fair distribution mechanism to split the dropped money among party members.

Highlights

• Experience Calculation Consistency: Recalculated experience for money drops in party scenarios to include game rates and multipliers, ensuring consistency with solo play.
• Party Money Distribution: Implemented logic to divide dropped zen among eligible party members on the same map, preventing an imbalance in money acquisition.

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[gemini-code-assist]

Code Review

This pull request adjusts money and experience calculations for NPC drops when the killer is in a party, aiming to make party drops more consistent with solo play. However, several issues were identified: dividing physical money drops by party size penalizes groups since only one player can collect the item, and there is a potential NullReferenceException when accessing player attributes. Additionally, the experience calculation logic is duplicated from other classes and should be refactored into a shared utility to prevent future maintenance issues.

[nolt]

/gemini summary

[gemini-code-assist]

Summary of Changes

This pull request addresses an imbalance in the game's economy where party members received significantly less zen (money) than solo players due to differences in how experience-based drops were calculated. By refactoring the experience calculation logic and updating the money pickup system, the changes ensure that zen drops are consistent with server rates and that wealth is distributed equitably among party members.

Highlights

• Experience Calculation Refactoring: Extracted the experience calculation logic into a shared method, 'CalculateExpAfterKill', to eliminate code duplication and ensure consistency between experience gain and zen drop calculations.
• Party Zen Drop Normalization: Updated the zen drop logic to use the solo experience formula for party members, ensuring that game rates and personal bonuses are correctly applied regardless of party status.
• Fair Party Money Distribution: Implemented a new mechanism in 'DroppedMoney' that automatically splits picked-up zen among all eligible party members on the same map, replacing the previous single-player pickup behavior.

New Features

🧠 You can now enable Memory (public preview) to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Activity

• The pull request was created by nolt.
• Gemini Code Assist provided initial feedback regarding potential issues with party money distribution, null-safety, and code duplication.
• The author addressed all feedback by refactoring the experience calculation, adding null-conditional access for attributes, and implementing a fair distribution logic for party money pickups.