Perf alloc

[scamiv]

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Resolves #(issue number)

Description:

PR Title

perf(core): reduce hot-path allocations & safe optimizations

This PR brings in a set of allocation-focused optimizations in core hot paths

Scope

• src/core/execution/NukeExecution.ts
• src/core/execution/WarshipExecution.ts
• src/core/game/UnitGrid.ts
• src/core/game/PlayerImpl.ts
• src/core/configuration/DefaultConfig.ts
• src/core/execution/SAMLauncherExecution.ts

What Changed

• NukeExecution.detonate: reduced call overhead/allocations by caching mg/config, avoiding repeated lookups, and using allocation-free loops (no forEach closures) in the diminishing-effect pass.
• WarshipExecution.findTargetUnit: replaced allocate+sort flow with single-pass best-target selection.
• UnitGrid.nearbyUnits: reduced call overhead and allocations via single-type fast path and cached query coordinates.
• PlayerImpl.units: added fast paths for common small-arity type queries (1-3 unit types).
• DefaultConfig.unitInfo: cached UnitInfo objects per UnitType to avoid repeated object/closure creation.
• SAMLauncherExecution targeting: removed sort churn and streamlined target selection with single-pass hydrogen prioritization.

Rebase

• One conflict was resolved in NukeExecution.detonate by keeping main's diminishing-effect-per-impacted-tile behavior, while retaining the allocation-reduction refactors.

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• I have added relevant tests to the test directory
• I confirm I have thoroughly tested these changes and take full responsibility for any bugs introduced

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Walkthrough

Introduces caching for unit info, several performance optimizations in execution and game layers (reducing allocations and repeated property access), and refactors targeting logic to pick a single best target instead of building/sorting candidate lists.

Changes

Cohort / File(s)	Summary
Unit Info Caching src/core/configuration/DefaultConfig.ts	Added private unitInfoCache: Map<UnitType, UnitInfo> and refactored unitInfo to consult/cache results. Reworked switch to assign a local info and store it. Port costWrapper now includes Factory; Train handled explicitly.
Nuke Execution src/core/execution/NukeExecution.ts	Introduced local aliases (mg, config) and local variables to avoid repeated property access. Rewrote loops to use for-of and local captures, clarified unit deletion/filtering, and centralized distance checks via mg. No exported API changes.
SAM Launcher Targeting Refactor src/core/execution/SAMLauncherExecution.ts	Reworked interception flow to reduce allocations: conditional Set creation for nearby nukes, removed isInRange, updated computeInterceptionTile signature to accept samTile and rangeSquared, and replaced target-array accumulation with a single best-target selection (HydrogenBomb prioritized).
Warship Target Selection src/core/execution/WarshipExecution.ts	Replaced array-and-sort target selection with single bestUnit tracking using typePriority and distance. Cached local mg, config, owner, and patrolTile; added explicit TradeShip handling and patrol-range checks.
Player Unit Filtering src/core/game/PlayerImpl.ts	Added fast paths for units(...) when requesting 0–3 types to avoid Set allocations; preserved Set-based logic for >3 types. Semantics unchanged.
Unit Grid Lookup src/core/game/UnitGrid.ts	nearbyUnits now branches for single vs. multi-type queries, inlines distance computation, and uses local gm, x, y to reduce repeated lookups. Adds optimized multi-type aggregation while keeping single-type behavior equivalent.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🛠️ Small caches hum, old loops unwind,
Targets chosen sharp, no lists to bind,
Fast paths skip the extra Set,
Grid math shrinks each repeated get,
Tiny changes, smoother mind.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The PR title 'Perf alloc' is vague and does not clearly convey the main change; it lacks specificity about performance optimizations in core hot paths.	Use a more descriptive title like 'Reduce hot-path allocations across core execution and grid systems' to clearly communicate the optimization focus.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description check	✅ Passed	The description clearly details performance optimizations across multiple files with specific scope, changes, and implementation details.

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@src/core/game/UnitGrid.ts`:
- Around line 180-183: TypeScript isn't narrowing the union for `types` before
it's used in the nested loops (causing TS2345 on `Map.get`), so add an explicit
assertion to treat it as a single UnitType; change the local binding used in the
loops (the `type` constant derived from `types`) to be asserted as `UnitType`
(or assert at the `get` call) so `this.grid[cy][cx].get(...)` receives a
`UnitType` rather than `UnitType | readonly UnitType[]`; update the binding
where `const type = types` is declared to use the assertion (or replace the
argument to `get` with `types as UnitType`) to satisfy the type checker.