Reference

NuGet package

The core engine ships as a standalone NuGet package: LinuxDevTyper.Core. It contains all typing, rating, trend, difficulty, weakness, and guided-mode logic with zero UI dependencies. You can embed it in your own .NET application, build a different frontend, or use it for automated typing analysis.

The package targets .NET 8 and has no external dependencies beyond the BCL.

Test suite

The project includes 817 xUnit tests organized across multiple test classes:

Test area	What it covers
RatingEngineTests	Elo adjustment math, edge cases, profile-tuned constants.
TrendEngineTests	Window splitting, trend classification, plateau detection, consecutive decline filtering.
FatigueDetectorTests	Sitting boundary detection, break triggers, accuracy drop calculation.
InsightEngineTests	Priority ordering, dismissal, intent-awareness, milestone detection.
SnippetSelectorTests	Difficulty matching, weakness boost, focus categories, edge pools.
SessionPlannerTests	Mix distribution, yo-yo lock, manual lock, comfort zone establishment.
PlannerInvariantTests	Structural invariants that must hold across all planner states.
PlannerEdgeCaseTests	Empty pools, single-snippet pools, extreme ratings.
PlannerProfileTests	Profile-tuned planner behavior.
PlannerPerformanceTests	Selection latency under large snippet pools.
MistakeAggregatorTests	Category aggregation, top-weakness extraction.
SymbolClassifierTests	Character-to-category mapping for all 10 categories.
WeaknessDetectorTests	Rolling window, fallback to lifetime profile, cold start.
WeaknessWindowTests	Time decay, event recording, category extraction.
WeaknessInvariantTests	Structural guarantees on weakness data.
DifficultyMemoryTests	Comfort zone, yo-yo detection, outlier filtering, difficulty aging.
SchemaMigratorTests	Every migration path from v1 through v12.
MigrationAuditTests	Cross-version migration with data preservation verification.
PackValidatorTests	Pack format validation, invalid pack rejection.
PortableBundleTests	Import/export, merge behavior, format versioning.
ContentIntegrationTests	End-to-end content pipeline from ingestion to selection.
CalibrationPackTests	Built-in snippet integrity and difficulty derivation.
PracticeProfileTests	Parameter clamping, diff comparison, default immutability.
XpEngineTests	XP calculation, repeat decay, sloppy penalty.
SummaryStatsEngineTests	Monthly summary aggregation.
ExplanationBuilderTests	Selection reason formatting.
ReasonFormatterTests	Weakness context appending.

Run the full suite:

dotnet test src/LinuxDevTyper.Core.Tests/ -c Release

Persistence

All user data is stored in a single state.json file. The current schema is version 12, with automatic migration from any previous version.

State structure

Field	Type	Purpose
SchemaVersion	int	Current: 12. Triggers migration on load.
Profile	Profile	User identity and per-language ratings.
Settings	AppSettings	UI preferences, audio settings, feature flags.
RecentResults	List<Result>	Last 200 session results. Older results roll into monthly summaries.
MistakeProfile	MistakeProfile	Cumulative per-category mistake counts (lifetime).
MistakeHeatmap	MistakeHeatmap	Per-character hit/miss tracking for fine-grained analysis.
WeaknessWindow	WeaknessWindow	Time-decayed rolling mistake data.
WeaknessSnapshots	List	Daily snapshots of weakness state, capped at 90 entries.
DifficultyMemory	DifficultyMemory	Per-language, per-difficulty performance records and yo-yo state.
PersonalDefaults	PersonalDefaults	User’s preferred starting configuration.
SessionSummaryByMonth	Dictionary	Aggregated stats for months whose sessions rolled off the 200-cap.
PracticeProfiles	Dictionary	Named practice profiles with tuning overrides.
PackRegistry	List<PackMetadata>	Discovered user packs with enabled/disabled state.

The 200-result cap keeps the file small. When results roll off, they are summarized into SessionSummaryByMonth so historical stats are preserved without unbounded growth.

Schema migration

The SchemaMigrator applies incremental migrations from any previous version to v12. Each migration step is idempotent. The migration audit test suite verifies every path from v1 through v12 preserves data integrity.

Audio system

Keyboard sound themes

Five keyboard themes ship with the app, each containing a set of WAV samples for keypress feedback:

1. AlpsCream — vintage Alps-style switches.
2. Mechanical — classic mechanical keyboard.
3. Membrane — soft membrane keyboard.
4. SoftTouch — quiet, dampened keys.
5. Topre — electrostatic capacitive switches.

Ambient soundscapes

Four ambient categories provide background atmosphere:

1. Ocean — waves and coastal sounds.
2. Rain — rainfall and gentle thunder.
3. Wind — breezy outdoor ambience.
4. Zen — calm, meditative tones.

Volume controls, mute toggle, and a shuffle button for random ambient selection are available in the settings sidebar. Audio is powered by MiniAudio through the MiniAudioService. A StubAudioService is available for headless/test environments.

Accessibility

• Keyboard-first navigation — every function is reachable without a mouse.
• Reduced sensory mode — disable ambient sounds and minimize visual effects.
• High contrast support — respects system high-contrast settings via Avalonia’s theme system.
• No time pressure — there is no countdown timer or penalty for typing slowly. WPM is tracked but never gates access to content.

Security scope

Linux Dev Typer is a fully offline desktop application with a minimal security surface:

• No network access — the app makes zero HTTP requests. No telemetry, no analytics, no update checks.
• No accounts — no registration, no login, no authentication.
• Local-only persistence — state.json lives in the user’s config directory. No cloud sync.
• No shell execution — the app never spawns child processes or executes shell commands.
• User-scoped file access — reads and writes only within ~/.config/linux-dev-typer/ and the application directory.
• Import validation — all imported content (packs, bundles, files) is validated before entering the engine. Invalid data is rejected, not silently accepted.