⚡ Bolt: [performance improvement] Optimize derived state memoization

[ereezyy]

💡 What: Added useMemo hooks to memoize derived state variables such as playerHorses, eligibleMares, eligibleStallions, and the BreedingEngine instance in BreedingCenter.tsx and TournamentCenter.tsx.
🎯 Why: Filtering the global horses array is an O(N) operation. Executing it on every single render can cause noticeable lag and performance degradation when the array scales up. Similarly, instantiating new BreedingEngine() repeatedly inside a React component wastes CPU cycles and triggers excess garbage collection.
📊 Impact: Considerably reduces render time in heavily data-driven components by avoiding repetitive iterations. Prevents unnecessary instantiation of services on every render, enhancing FPS during UI interactions and animations.
🔬 Measurement: Verify rendering performance via React DevTools Profiler by toggling tabs and inspecting the component render durations. The time taken to calculate these specific variables should drop from proportional to N to 0ms across subsequent renders (when dependencies are unchanged).

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PR created automatically by Jules for task 3810973659073426183 started by @ereezyy

Summary by Sourcery

Optimize horse-related derived state and service instantiation to reduce repeated computation on re-renders in breeding and tournament flows.

Enhancements:

• Memoize BreedingEngine instantiation in BreedingCenter to prevent recreating the engine on every render.
• Memoize filtered player horse lists and eligible breeding subsets in BreedingCenter to avoid repeated O(N) filtering.
• Memoize the player horse list in TournamentCenter to avoid recomputing ownership-based filters on each render.

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[sourcery-ai]

Reviewer's Guide

This PR memoizes expensive derived state and service instantiation in BreedingCenter and TournamentCenter by wrapping horse filters and the BreedingEngine creation in useMemo, reducing repeated O(N) computations and object allocations on every render.

Sequence diagram for memoized derived state and BreedingEngine in BreedingCenter

sequenceDiagram
  participant ReactRender as ReactRender
  participant useMemoBreedingEngine as useMemo_BreedingEngine
  participant useMemoPlayerHorses as useMemo_PlayerHorses
  participant useMemoEligibleMares as useMemo_EligibleMares
  participant useMemoEligibleStallions as useMemo_EligibleStallions

  rect rgb(230,230,255)
    ReactRender->>useMemoBreedingEngine: initial render
    useMemoBreedingEngine-->>ReactRender: create new BreedingEngine

    ReactRender->>useMemoPlayerHorses: deps horses, playerWalletAddress
    useMemoPlayerHorses-->>ReactRender: filter horses by owner

    ReactRender->>useMemoEligibleMares: deps playerHorses
    useMemoEligibleMares-->>ReactRender: filter playerHorses by mare criteria

    ReactRender->>useMemoEligibleStallions: deps horses, selectedMareId
    useMemoEligibleStallions-->>ReactRender: filter horses by stallion criteria
  end

  rect rgb(230,255,230)
    ReactRender->>useMemoBreedingEngine: subsequent render, deps unchanged
    useMemoBreedingEngine-->>ReactRender: return cached BreedingEngine

    ReactRender->>useMemoPlayerHorses: deps unchanged
    useMemoPlayerHorses-->>ReactRender: return cached playerHorses

    ReactRender->>useMemoEligibleMares: deps unchanged
    useMemoEligibleMares-->>ReactRender: return cached eligibleMares

    ReactRender->>useMemoEligibleStallions: deps changed by selectedMareId
    useMemoEligibleStallions-->>ReactRender: recompute eligibleStallions
  end

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Flow diagram for memoized derived state in BreedingCenter and TournamentCenter

flowchart TD
  subgraph BreedingCenter
    H(horses)
    P(playerWalletAddress)
    SM(selectedMareId)

    PH["playerHorses = useMemo(filter horses by owner)"]
    EM["eligibleMares = useMemo(filter playerHorses by mare criteria)"]
    ES["eligibleStallions = useMemo(filter horses by stallion criteria and selectedMareId)"]
    BE["breedingEngine = useMemo(new BreedingEngine)"]

    H --> PH
    P --> PH
    PH --> EM
    H --> ES
    SM --> ES
    BE
  end

  subgraph TournamentCenter
    H2(horses)
    P2(playerWalletAddress)

    PH2["playerHorses = useMemo(filter horses by owner)"]

    H2 --> PH2
    P2 --> PH2
  end

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File-Level Changes

Change	Details	Files
Memoize BreedingCenter derived state and BreedingEngine instance to avoid recomputation on every render.	Wrap BreedingEngine instantiation in a useMemo with an empty dependency array to reuse a single instance across renders. Wrap the player horses filter in useMemo, depending on the global horses array and the player wallet address. Wrap the eligible mares computation in useMemo, depending on the memoized player horses list. Wrap the eligible stallions computation in useMemo, depending on the global horses array and currently selected mare id.	src/components/BreedingCenter.tsx
Memoize TournamentCenter player horses derived state to avoid repeated filtering.	Wrap the player horses filter in useMemo, depending on the global horses array and the player wallet address.	src/components/TournamentCenter.tsx

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[sourcery-ai]

Hey - I've found 1 issue, and left some high level feedback:

• Consider using useRef instead of useMemo for the new BreedingEngine() instance to make it explicit that this is a stable, long-lived object reference and to avoid accidental re-instantiation if dependencies ever change.
• If horses is provided from a store or selector that creates a new array reference on each update, the useMemo calls depending on horses may not yield much benefit; you might get better wins by memoizing or normalizing horses closer to its source so these arrays are stable across unrelated updates.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Consider using `useRef` instead of `useMemo` for the `new BreedingEngine()` instance to make it explicit that this is a stable, long-lived object reference and to avoid accidental re-instantiation if dependencies ever change.
- If `horses` is provided from a store or selector that creates a new array reference on each update, the `useMemo` calls depending on `horses` may not yield much benefit; you might get better wins by memoizing or normalizing `horses` closer to its source so these arrays are stable across unrelated updates.

## Individual Comments

### Comment 1
<location path="src/components/BreedingCenter.tsx" line_range="36-37" />
<code_context>
-    h.stats.age <= 180 && // 3-15 years
-    h.genetics.rarity !== 'Legendary' // Legendary horses can't breed normally
-  );
+  // Memoize the breeding engine to avoid instantiating it on every render
+  const breedingEngine = useMemo(() => new BreedingEngine(), []);

-  const eligibleStallions = horses.filter(h => 
</code_context>
<issue_to_address>
**issue (bug_risk):** Reusing a single BreedingEngine instance may change previous behavior if the engine holds mutable state.

With this change, the engine instance now lives for the full lifetime of the component instead of being re-created on each render. If `BreedingEngine` keeps mutable internal state or caches based on prior calls, this can introduce subtle bugs (stale data, cross-call contamination, etc.). If it’s not strictly stateless, consider either preserving the per-render instantiation or refactoring `BreedingEngine` to be stateless and moving any caching outside the instance.
</issue_to_address>

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[sourcery-ai]

issue (bug_risk): Reusing a single BreedingEngine instance may change previous behavior if the engine holds mutable state.

With this change, the engine instance now lives for the full lifetime of the component instead of being re-created on each render. If BreedingEngine keeps mutable internal state or caches based on prior calls, this can introduce subtle bugs (stale data, cross-call contamination, etc.). If it’s not strictly stateless, consider either preserving the per-render instantiation or refactoring BreedingEngine to be stateless and moving any caching outside the instance.