API Index (Condensed)

A condensed reference (~300 lines) of the most important types in ActualLab.Fusion. Use this to find existing abstractions before writing new code. See also: Full API Index (~1000 lines).

Core (ActualLab.Core) — PartCore.md

Result, Option, Requirement

• Result<T> (struct) — computation result holding value or error
• Option<T> (struct) — optional value (Some/None)
• Requirement<T> (record) — validates values and produces errors on failure

Time — PartCore-Time.md

• Moment (struct) — UTC timestamp (wraps DateTime)
• MomentClock — abstract clock producing Moment timestamps
• CpuClock — monotonic high-resolution clock (Stopwatch-based)
• ServerClock — clock with offset from base clock (for client-side server time)
• SystemClock — real UTC clock via DateTime.UtcNow
• CoarseSystemClock — low-overhead periodically-updated clock
• MomentClockSet — set of related clocks (system, CPU, server, coarse)
• TimerSet<T> — priority-based timer set backed by radix heap
• ConcurrentTimerSet<T> — sharded concurrent version of TimerSet
• TickSource — shared coalesced timer tick for multiple consumers
• RetryDelaySeq (record) — retry delay sequence (fixed/exponential backoff with jitter)

Collections — PartCore-PropertyBag.md

• PropertyBag (struct) — immutable typed property bag
• MutablePropertyBag — thread-safe mutable property bag with change notifications
• OptionSet — thread-safe mutable set of named options
• RingBuffer<T> (struct) — fixed-capacity circular buffer (power-of-2 capacity)
• ArrayBuffer<T> (struct) — ArrayPool-backed list-like buffer (zero alloc)
• ArrayOwner<T> — pooled array as IMemoryOwner<T>
• FixedArray0..16<T> (struct) — fixed-size inline stack arrays
• HashSetSlim1..4<T> (struct) — compact hash sets, inline before fallback to HashSet
• BinaryHeap<TPriority, TValue> — min-heap
• FenwickTree<T> — binary indexed tree for prefix sums
• ApiList<T>, ApiMap<TKey,TValue>, ApiSet<T>, ApiNullable<T> — serializable API contract collections

Async Primitives — PartCore-AsyncLock.md, PartCore-Worker.md

• AsyncLock — semaphore-based async lock with optional reentry detection
• AsyncLockSet<TKey> — keyed async lock set
• AsyncChain (record struct) — composable named async operation (retry, log, cancel)
• WorkerBase / IWorker — long-running background worker (start/stop)
• BatchProcessor<T, TResult> — dynamic-scale batched processing
• AsyncState<T> — linked-list async state transitions

Networking & Resilience — PartCore-Transiency.md

• Transiency (enum) — error transiency classification
• TransiencyResolver — classifies exceptions as transient/terminal/non-transient
• Connector<T> — persistent connection with auto-reconnect
• RetryDelayer — configurable retry delay with limits
• RetryPolicy (record) — retry with try count, per-try timeout, delay sequence
• ChaosMaker (record) — chaos engineering fault injection

Serialization

• IByteSerializer<T> / ITextSerializer<T> — core serialization interfaces
• ByteSerialized<T>, TextSerialized<T> — auto-serializing wrappers
• TypeDecoratingSerializer (byte & text) — prefixes data with type info for polymorphism
• ExceptionInfo — serializable exception snapshot

Specific serializers

• MessagePackByteSerializer — MessagePack binary serializer
• MemoryPackByteSerializer — MemoryPack binary serializer
• NerdbankMessagePackByteSerializer — Nerdbank.MessagePack binary serializer (in ActualLab.Serialization.NerdbankMessagePack)
• SystemJsonSerializer — System.Text.Json implementation
• NewtonsoftJsonSerializer — JSON.NET implementation

DI Helpers

• ServiceResolver — encapsulates service type + optional custom resolver
• HostedServiceSet — manages group of IHostedService as a whole
• ServiceCollectionExt / ServiceProviderExt — various DI extension methods

Text & IO — PartCore-Symbol.md

• Symbol (struct) — interned string with fast equality
• FilePath (struct) — cross-platform file path abstraction
• ListFormat (struct) — delimiter-based list serialization/parsing
• Base64UrlEncoder — URL-safe Base64 encoding (RFC 4648)
• JsonString — raw JSON value wrapper

Identifiers & Versioning

• HostId (record) — unique host identifier
• VersionGenerator<T> — abstract version generator
• ClockBasedVersionGenerator — monotonic long versions from clock ticks

Reflection & Codegen

• MemberwiseCopier — reflection-based property/field copier

Hashing & Sharding Helpers

• ShardMap<TNode> — maps shards to nodes via consistent hashing
• HashRing<T> — consistent hash ring

RPC (ActualLab.Rpc) — PartR.md

• IRpcService — marker for RPC-invocable services
• RpcStream<T> — typed RPC stream with batched delivery
• RpcHub — central hub managing peers, services, configuration
• RpcPeer — one side of an RPC channel (connection, serialization, call tracking)
• RpcClientPeer / RpcServerPeer — client/server peer specializations
• RpcConnection — wraps transport + properties for a single connection
• RpcClient — establishes RPC connections to remote peers
• RpcWebSocketClient — client establishing connections via WebSocket

Service & Method Descriptors

• RpcServiceRegistry — registry of all RPC service definitions
• RpcServiceDef — describes a registered RPC service (type, mode, methods)
• RpcMethodDef — describes an RPC method (name, kind, serialization, timeouts)

Attributes

• RpcMethodAttribute — configures RPC method properties (name, timeouts, local execution mode)
• LegacyNameAttribute — backward-compatible RPC name mapping with max version

Configuration

• RpcBuilder (struct) — fluent builder for registering RPC services in DI
• RpcConfiguration — registered service builders + default service mode
• RpcLimits (record) — timeout/periodic limits for connections, keep-alive
• RpcCallTimeouts (record) — connect/run/log timeouts for outbound calls
• RpcServiceMode (enum) — local, server, client, or distributed

RPC Server — [ActualLab.Rpc.Server]

• RpcWebSocketServer — accepts WebSocket connections for ASP.NET Core

CommandR (ActualLab.CommandR) — PartC.md

• ICommand<T> — command producing result T
• ICommander — main entry point for executing commands through handler pipeline
• CommandContext / CommandContext<T> — tracks execution state within pipeline
• CommandHandler (record) — handler descriptor in execution pipeline

Attributes

• CommandHandlerAttribute — marks method as command handler
• CommandFilterAttribute — marks method as command filter

Pipeline

• CommandHandlerChain — ordered chain of filters + final handler
• CommandHandlerFilter — filters which handlers are used
• CommandHandlerRegistry — registry of all handlers, resolved from DI

Operations (used in Operations Framework)

• Operation — recorded operation (completed command execution)
• OperationEvent — event recorded during an operation (for eventual consistency)
• IOperationScope — manages operation lifecycle within command pipeline
• NestedOperation (record) — nested command within parent operation

Configuration

• CommanderBuilder (struct) — fluent builder for commander registration
• ICommandService — tagging interface for command service proxies
• IEventCommand — event dispatched to multiple handler chains

Fusion (ActualLab.Fusion) — PartF.md

• IComputeService — tagging interface for compute service proxies
• Computed<T> — cached computation result with invalidation support
• ComputedOptions (record) — configuration for compute method behavior
• ComputedRegistry — global registry of all Computed instances (weak refs, auto-prune)
• ComputeContext — tracks current compute call context

Attributes

• ComputeMethodAttribute — marks method as compute method (auto-cache + invalidation)
• RemoteComputeMethodAttribute — extends ComputeMethodAttribute with remote computed caching config

States — PartF-ST.md

• IState<T> / State — reactive state with computed value
• ComputedState<T> — state backed by a compute method
• MutableState<T> — manually settable reactive state
• StateFactory — creates state instances
• StateSnapshot — immutable snapshot of state lifecycle

Invalidation

• Invalidation — static helpers to check/begin invalidation scopes
• InvalidationSource (struct) — describes source of invalidation
• UpdateDelayer (record) — integrates with UIActionTracker for instant UI updates
• FixedDelayer (record) — fixed update delay with configurable retry delays

Sessions

• Session — authenticated user session (unique string Id)
• SessionFactory (delegate) — creates session instances
• SessionResolver — resolves current session
• ISessionCommand<T> — command scoped to a session

Remote/Client

• RemoteComputed<T> — Computed populated from remote RPC call
• RemoteComputedCache — abstract base for remote computed caches

Builder

• FusionBuilder (struct) — registers Fusion services in DI

Blazor (ActualLab.Fusion.Blazor) — PartB.md

Components

• ComputedStateComponent<T> — Blazor component backed by ComputedState<T>
• MixedStateComponent<T, TMutableState> — computed + mutable state component
• FusionComponentBase — base component with custom parameter comparison
• StatefulComponentBase<T> — component owning a typed IState<T>
• CircuitHubComponentBase — base component accessing CircuitHub services

Attributes

• FusionComponentAttribute — enables custom parameter comparison and event handling on a component
• ParameterComparerAttribute — assigns a custom ParameterComparer to a component parameter

UI Services — PartB-UICommander.md

• UICommander — executes commands wrapped in tracked UIAction
• UIActionTracker — tracks running/completed UIAction instances
• UIAction<T> — strongly-typed tracked UI action
• CircuitHub — scoped service caching Blazor & Fusion services (dispatcher, session, etc.)

Server-Side Services & Helpers

• SessionMiddleware — resolves/creates Session from cookies
• FusionWebServerBuilder (struct) — configures RPC, session middleware, render mode
• ServerAuthHelper — syncs ASP.NET Core auth state with Fusion IAuth

Entity Framework (ActualLab.Fusion.EntityFramework) — PartEF.md

• DbHub<TDbContext> — creates DbContext with execution strategy and operation scope
• DbServiceBase<TDbContext> — base for DB services with DbHub access
• DbContextBase — DbContext base solving EF Core pooled disposal issues
• DbEntityResolver<TDbContext, TKey, TDbEntity> — batched entity resolution via BatchProcessor
• DbEntityConverter<TDbContext, TDbEntity, TModel> — entity-to-model conversion

Operations — PartO.md

• DbOperationScope<TDbContext> — manages transaction, operation/event persistence, commit
• DbOperation — persisted operation entity for cross-host replication
• DbEvent — persisted operation event entity with delayed processing

Sharding

• DbShard — identifies a database shard
• DbShardResolver<TDbContext> — resolves shards from Session, IHasShard, ISessionCommand
• DbShardRegistry<TContext> — maintains shard sets, tracks used shards
• ShardDbContextFactory<TDbContext> — per-shard DbContext factory

Log Processing

• DbLogReader<TDbContext, TKey, TDbEntry, TOptions> — shard-aware batched log reader
• DbLogWatcher<TDbContext, TDbEntry> — detects log changes per shard
• DbLogTrimmer — trims old log entries by age
• DbOperationLogReader<TDbContext> — reads operation logs for cache invalidation
• DbEventLogReader<TDbContext> — reads event logs for command dispatch

Log Watcher Implementations

• NpgsqlDbLogWatcher — PostgreSQL LISTEN/NOTIFY
• RedisDbLogWatcher — Redis pub/sub
• FileSystemDbLogWatcher — file system watchers
• LocalDbLogWatcher — in-process notifications

Authentication — PartAA.md

Contracts

• IAuth — primary auth service (sign-out, edit user, presence, session/user queries)
• IAuthBackend — backend auth (sign-in, session setup, options management)
• User (record) — authenticated/guest user with claims, identities, version
• SessionInfo (record) — session details (version, timestamps, IP, user agent)
• SessionAuthInfo (record) — auth info for session (identity, user ID, forced sign-out)

Commands

• AuthBackend_SignIn (record) — sign in with identity
• Auth_SignOut (record) — sign out session
• Auth_EditUser (record) — edit user profile

Blazor Auth

• AuthStateProvider — Fusion-aware AuthenticationStateProvider
• ClientAuthHelper — client-side sign-in/out via JS interop

Interceptors & Proxies (ActualLab.Interception) — PartAP.md

• IProxy — proxy object with assignable Interceptor
• Interceptor — base class for method interceptors
• MethodDef — describes an intercepted method (return type, params, async detection)
• Invocation (struct) — single intercepted method invocation (proxy, method, args, delegate)
• ArgumentList (record) — immutable argument list for intercepted calls (0..10 args)
• Proxies — factory for creating proxy instances
• TypedFactoryInterceptor — resolves instances via DI (ActivatorUtilities)
• ScopedServiceInterceptor — resolves scoped service per call
• SchedulingInterceptor — schedules async invocations via TaskFactory

Redis Helpers (ActualLab.Redis)

• RedisConnector — resilient Redis connection with auto-reconnect
• RedisDb<T> — typed Redis DB scoped by context
• RedisPub<T> — typed pub/sub publisher
• RedisQueue<T> — Redis-backed FIFO queue
• RedisStreamer<T> — streaming read/write over Redis Streams
• RedisHash — Redis hash operations (get, set, remove, increment)
• RedisSubBase — abstract Redis pub/sub subscriber base