chore: Ponytail over-engineering audit — ~700 lines, 21 deps, 3 projects to cut

[reakaleek]

What

Full repo ponytail audit surfaced ~900 lines of removable code, 21 dead or replaceable dependencies, 56 dead asset files, and 3 micro-projects that add solution sprawl without boundary benefit.

All findings are verified (grepped for actual usage, not estimated). Re-audited 2026-07-07 — see the audit-refresh comment below for what changed.

Subtasks

C# / .NET

• chore: Remove single-implementation C# interfaces #3569 — Remove single-implementation C# interfaces (~180 lines)
• chore: Replace hand-rolled code with BCL/stdlib equivalents #3570 — Replace hand-rolled code with BCL/stdlib equivalents (~170 lines, fixes one separator bug)
• chore: Simplify verbose C# code with LINQ and idiomatic patterns #3571 — Simplify verbose C# code with LINQ and idiomatic patterns (~225 lines)
• chore: Delete dead C# code #3572 — Delete dead C# code (~150 lines + 56 dead SVG files)
• chore: Remove dead/unused NuGet packages #3566 — Remove unused NuGet packages (9 packages from Directory.Packages.props)
• chore: Consolidate micro-projects in src/ #3573 — Consolidate micro-projects in src/ (−3 projects)

TypeScript / Frontend

• chore: Remove unused npm packages #3567 — Remove unused npm packages (uuid, tippy.js, moment, text-diff)
• chore: Replace npm deps with native browser APIs #3568 — Replace npm deps with native browser APIs (ua-parser-js, @uidotdev/usehooks, lodash, select-dom, smooth-scroll.ts → CSS)

Net reduction

	Cut
C# lines	~900
Dead asset files	56 token SVGs
NuGet packages	−9 packages, −3 projects
npm packages	−4 dead, −4 native replacements

~900 lines, −56 files, −13 NuGet deps, −7 npm deps, −3 projects possible.

[reakaleek]

Re-audit 2026-07-07

Ran a fresh repo-wide audit (every finding grep-verified) and reconciled it with this tracker:

Corrections — #3569 had six false positives that would have broken tests if executed as written; all moved to the excluded list:

• IGitHubReleaseService, IGitHubPrService, IGcpIdTokenProvider, IS3EtagCalculator — mocked via A.Fake<> in tests
• IRepositoryTracker, IParserResolvers — each has a second implementation

Additions (all verified single-impl/no-mock or fully dead):

• chore: Remove single-implementation C# interfaces #3569: +13 interfaces (IDescriptionGenerator, ILinkIndexWriter/ILinkIndexReaderWriter, IChangesService, IDocumentGateway, IAskAiMessageFeedbackService, IGitRepository, IProductNameLookup, IChangelogMarkdownRenderer, IDocumentationFileOutputProvider, essc ISitemapParser/IAdaptiveCrawler/IDocumentExporter<T>)
• chore: Delete dead C# code #3572: Svg tokens/ icon set (56 dead files + ~90 lines of plumbing), IConversionCollector (zero implementations), ICodexModel/ICodexPageRenderer (never implemented or called)
• chore: Simplify verbose C# code with LINQ and idiomatic patterns #3571: inline AddLlmMarkdownExport (one-line duplicate, one caller)
• chore: Replace npm deps with native browser APIs #3568: delete smooth-scroll.ts in favour of CSS scroll-behavior: smooth
• chore: Consolidate micro-projects in src/ #3573: delete the IService marker outright when merging instead of moving it

Deliberately retained: the IDocsSyncPlanStrategy/IDocsSyncApplyStrategy exclusion (named strategy pattern). #3566 and #3567 re-verified as still accurate.

Net totals updated in the issue body: ~900 lines, −56 files, −13 NuGet deps, −7 npm deps, −3 projects.