[efficiency-improver] perf: eliminate LINQ Select+Where+ToList+ToArray allocation in TaxonomySearchContext.SearchableFields

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🤖 This PR was created by Efficiency Improver, an automated AI assistant.

Focus Area

Code-Level Efficiency

Goal

TaxonomySearchContext.SearchableFields built its result with MultiFields.GetMergedFieldInfos(reader).Select(x => x.Name).ToList() followed by a second .Where(...).ToArray() chain. This allocates two LINQ iterator/state-machine objects (Select + Where) plus an intermediate List<string> buffer, on every rebuild of the searchable-fields cache. The sibling class SearchContext.SearchableFields already had this exact pattern eliminated in PR #545, but TaxonomySearchContext (used for the facets/taxonomy search path) was missed.

Approach

Replaced the two-stage LINQ chain with a single pre-sized List<string> (capacity = FieldInfos.Count) populated via one foreach loop that inlines the filter condition, then materialized once with .ToArray(). Removed the now-unused using System.Linq; and added using System.Collections.Generic;. Behavior is unchanged — same field names, same order, same filtering of special/facet fields, same caching semantics (only non-empty results are cached).

Energy Efficiency Evidence

Proxy metric: memory allocation (reduced iterator/state-machine + intermediate list allocations), which maps to energy via reduced GC/DRAM churn — the same methodology used in the previously-merged PR #545 for the equivalent SearchContext.SearchableFields fix.

This method rebuilds at most once per TaxonomySearchContext lifetime (or once per empty-index probe), so per-call savings are small, but the pattern eliminates 2 iterator allocations + 1 intermediate List<string> per rebuild with zero behavioral change.

Green Software Foundation Context

• Hardware Efficiency: Fewer short-lived allocations reduce Gen0 GC pressure, making better use of CPU cache/memory bandwidth per functional unit of work (SCI: Energy component reduced, functional unit unchanged).

Trade-offs

None identified — public API/behavior unchanged. The explicit loop is marginally more verbose than the LINQ chain but stays simple and matches the already-established pattern in SearchContext.SearchableFields.

Test Status

• dotnet build src/Examine.sln --configuration Release — succeeded, 0 errors, 0 warnings.
• dotnet test src/Examine.Test/Examine.Test.csproj -f net8.0 --configuration Release — 316 passed, 0 failed, 2 skipped.

Reproducibility

dotnet build src/Examine.sln --configuration Release
dotnet test src/Examine.Test/Examine.Test.csproj -f net8.0 --configuration Release

Generated by Efficiency Improver · auto · 67 AIC · ⌖ 12.4 AIC · ⊞ 17.6K · ◷

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