Changelog

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Overview

• Unified versioning — All packages share a single version number
• Package consolidation — Many separate packages merged into core effect
• Unstable modules — New functionality under effect/unstable/* paths
• Performance improvements — Rewritten fiber runtime with reduced memory overhead
• Better tree-shaking — Aggressive bundle size optimization

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Latest Beta Release: v4.0.0-beta.21

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Fixes

• Fixed Stream.withSpan options handling
• Fixed TxPubSub.publish and TxPubSub.publishAll to require Effect.Transaction in return environment
• Fixed MCP resource template parameter names resolving as param0, param1
• Fixed Schedule.reduce to persist state updates for synchronous combine functions
• Fixed TupleWithRest post-rest validation to check each tail index sequentially
• Constrained HttpServerRequest.source to object type
• Renamed WorkflowEngine.layer (breaking change)
• Fixed Workflow.executionId to use schema makeUnsafe
• Fixed spans never having parent span

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New Features

• Added Effect.findFirst and Effect.findFirstFilter for short-circuiting effectful searches

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Recent Changes

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v4.0.0-beta.20

• Moved ChildProcess APIs into spawner service
• Reverted Config.withDefault to v3 behavior (eager values)
• Changed default ErrorReporter severity to Info

• Added ServiceMap.Key type as base for ServiceMap.Service and ServiceMap.Reference
• Added dedicated AiError metadata interfaces per reason
• Added Model.ModelName service
• Reverted Effect.partition to v3 behavior (accumulates failures, never fails)

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v4.0.0-beta.19

• Added transactional STM modules: TxDeferred, TxPriorityQueue, TxPubSub, TxReentrantLock, TxSubscriptionRef
• Refactored transaction model: removed Effect.atomic/Effect.atomicWith, added Effect.withTxState
• All Tx operations now return Effect<A, E, Transaction> requiring explicit Effect.transaction(...) at boundaries
• Removed TxRandom module

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v4.0.0-beta.18

• Fixed Command.withGlobalFlags type inference with mixed flag types
• Ensured OpenAI JSON schemas for tool calls are properly transformed

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v4.0.0-beta.17

• Fixed Schema.encodeKeys to encode non-remapped struct fields during encoding

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v4.0.0-beta.16

• Added SchemaParser.makeOption and Schema.makeOption for constructing schema values as Option
• Added OptionFromUndefinedOr and OptionFromNullishOr schemas

• Fixed OpenAPI Multipart file upload schema generation

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v4.0.0-beta.15

• Fixed Stream.groupedWithin to stop emitting empty arrays when schedule ticks fire while upstream is idle
• Allowed creating standalone HTTP handlers from HttpApiEndpoints
• Fixed atom node timeout cleanup
• Refined ExtractServices to omit tool handler requirements when automatic tool resolution is disabled

• Refactored unstable CLI global flags to command-scoped declarations
• Removed GlobalFlag.add, GlobalFlag.remove, GlobalFlag.clear
• Added Command.withGlobalFlags(...) as declaration API
• Changed GlobalFlag.setting constructor to curried form

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v4.0.0-beta.14

• Made CLI global settings directly yieldable (now extends ServiceMap.Reference)
• Renamed built-in globals:
  • GlobalFlag.CompletionsFlag → GlobalFlag.Completions
  • GlobalFlag.LogLevelFlag → GlobalFlag.LogLevel

• Fixed OpenApi.fromApi preserving multiple response content types for one status code

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v4.0.0-beta.13

• Exposed NoSuchElementError in stream-based Atom.make overloads
• Updated unstable schema variant helpers to use array-based arguments
• Added Schedule.fixed for fixed-interval scheduling

• Fixed request resolver batch fibers to run with request services
• Fixed Schedule.fixed double-executing effects due to clock jitter
• Used identifier annotation as expected message when available

• Refactored built-in CLI options to use Effect services with GlobalFlag
• Added visibility for built-in flags in help output
• Enabled custom global flags via GlobalFlag.add

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v4.0.0-beta.12

• Added Config.nested combinator to scope config under named prefix
• Added Random.nextBoolean for generating random booleans
• Added Graph.toMermaid for generating Mermaid diagrams
• Fixed HttpClient.retryTransient autocomplete
• Fixed Schema.encodeKeys to work with Schema.Class
• Fixed Atom.searchParam to decode initial URL values correctly
• Added Effect.annotateLogsScoped for scoped log annotations

• Made fiber keepAlive setInterval evaluation lazy
• Used cause annotations for detecting client aborts
• Fixed LanguageModel stripping of resolved approval artifacts
• Fixed JSON-RPC serialization for non-batched requests

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v4.0.0-beta.11

• Added grouped subcommand support to Command.withSubcommands
• Added Command.withExamples to attach usage examples
• Added Command.annotate and Command.annotateMerge for command metadata
• Added Command.withShortDescription for subcommand listings
• Added Command.withAlias for command aliases

• Added Effect.validate for validating collections while accumulating failures
• Added WorkflowEngine.layer for in-memory workflow engine

• Fixed HashMap HAMT bit positions comparison
• Fixed unstable HTTP Headers prototype methods in for..in iteration
• Guarded keepAlive timer APIs for restricted runtimes
• Fixed Queue.collect duplicating drained messages
• Fixed Schema.TupleWithRest accepting inputs with missing post-rest elements
• Added ErrorReporter module

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v4.0.0-beta.10

• Added unstable/encoding subpath export
• Exported Effect do notation APIs (Do, bindTo, bind, let)
• Added Random.shuffle to shuffle iterables with seeded randomness

• Fixed race in Semaphore.take where interruption could leak permits
• Short-circuited Fiber.joinAll when called with empty iterable
• Simplified HTTP logger disabling
• Fixed UrlParams.Input usage in HTTP client and server
• Renamed HttpClient.retryTransient option mode to retryOn

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Migration from v3

• Migration Overview
• Services Migration
• Error Handling Migration
• Schema v4 Migration

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Full Changelog

• GitHub Releases
• CHANGELOG.md

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Versioning

• Stable modules (e.g. effect/Effect, effect/Schema) follow strict semver
• Unstable modules (e.g. effect/unstable/http) may receive breaking changes in minor releases
• All packages in the Effect ecosystem share the same version number

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Getting Updates

npm install effect@beta
# or
pnpm add effect@beta
# or
yarn add effect@beta

npm install @effect/platform-node@beta @effect/sql-pg@beta

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Reporting Issues

• GitHub Issues
• Discord Community