# What changed in effect

> 425 changes in effect 3 to 4 from its official release notes, upgrade guides and advisories: 59 breaking, 1 deprecations, 5 security, 103 new APIs and options. Each one cited. Sources checked 2026-10-18. HTML: https://unstale.sh/npm/effect/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## effect 4

### Breaking changes

- Supports structured decision instructions, descriptions, and score legends; accepts labeled descriptions. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- The dev metadata field is now a bigint. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- The ino, rdev, nlink, and blocks metadata fields are now Option<bigint>, preserving values outside the safe integer range. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Rejects object patterns with keys the input type does not have. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Rejects object patterns with keys the input type does not have. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Rejects object patterns with keys the input type does not have. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Rejects object patterns with keys the input type does not have. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Types require schema services for resource templates and encoding services for prompt parameters with completion handlers, catching missing services at compile time. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Criteria entries are now { label, description } objects instead of strings. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Rejects duplicate discriminants at compile time, including nested unions and numeric/string property-key collisions. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds the URL-parameter redaction defaults moved from Headers.CurrentRedactedNames; custom lists replace these defaults. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Failure-suspended workflows no longer retry failed activities until explicitly resumed; interrupting one completes it as interrupted without rerunning the activity. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Indexed containers with more than 20 holes are returned as objects keyed by index strings instead of sparse arrays; appending after the maximum array index no longer throws. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Indexed containers with more than 20 holes are returned as objects keyed by index strings instead of sparse arrays; appending after the maximum array index no longer throws. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Rejects single-header and multi-header trace contexts with invalid trace or span identifiers. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Subscriptions no longer receive deferred list-change notifications emitted before they subscribed; coalesced runtime changes are preserved. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Subsequent delta histogram exports omit min and max because cumulative extrema do not describe the reported interval. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- COMMIT errors become typed SqlError failures when cleanup succeeds; if cleanup fails, both errors remain defects to prevent typed recovery from hiding an unsafe connection state. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- The duplicate Anthropic response options for cache creation and cache reads are removed. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Config parsing preserves provider defects and interruption reasons, and `Config.orElse` no longer recovers mixed causes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- AI tracing renames the concurrency span attribute to `effect.ai.concurrency`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- AI tracing renames the object-name attribute, and object choices are JSON-encoded. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- AI tracing renames the tool-choice attribute; it records the resolved value and defaults to `auto`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Failures containing defects or interruptions are no longer retried. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Response encoding failures now return 500 and reach ErrorReporter; request decoding failures remain 400 and unreported, and response failures remain HttpApiSchemaError values. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Interrupt-only spans are Unset with `effect.fiber.interrupted: true` rather than Ok with an Interrupted description and legacy attributes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Missing required session headers and initialize requests carrying a session header now return JSON-RPC error bodies. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- OpenAI service-tier and system-fingerprint tracing attributes move from `gen_ai.openai.*` to `openai.*`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Each summary exports as one cumulative OTLP Summary metric named by its id rather than separate quantiles, count, and sum metrics; common units map to UCUM and large bigint values retain precision. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Writes store entry and remote IDs as BYTEA and decode BIGINT timestamps returned as strings or bigints; existing UUID tables require manual migration or recreation. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- AI tracing replaces the `system` option and `gen_ai.system` with `provider: { name }` and `gen_ai.provider.name`; related attribute types are renamed. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- NaN and fractional capacities are rejected to prevent nonterminating batch publication; Infinity remains supported. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The OpenAI response-format telemetry option and `WellKnownResponseFormat` are removed. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The data-last overload now returns the handler's error type instead of the original error type. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The AI tracing token option, token attribute types, and `gen_ai.token.type` span attribute are removed. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Suspended workflows are no longer replayed for unawaited deferred checkpoints, while interrupt wakes are preserved. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Concurrent callers share one computation, which is interrupted only after every caller is interrupted; interrupted results are not cached, and calls during finalization start fresh computations. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Replaces FiberRef. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Modules including effect/http, effect/rpc, and effect/schema import from effect/<area>; unstable APIs may break in minor releases, while untagged APIs follow semver. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Requires React 19. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Requires Deno 2.8.3 or newer. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Uses a built-in PostgreSQL client with pipelining, prepared statements, and binary codecs, and no longer depends on pg. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Uses Node's built-in node:sqlite and requires Node 22.16 or newer. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Runs property tests with the native Arbitrary module and supports Vitest fixtures. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Now returns successes before failures; swap tuple order from the previous `[failures, successes]` order. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Array, Chunk, Effect, and Record partition functions now return successes before failures; swap tuple order from the previous `[failures, successes]` order. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Now holds Queue.Taker entries; resume an entry with `entry.resume(...)` instead of calling it as a function. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Remains suspended until its requested batch is available instead of entering a synchronous retry loop that can starve the host. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- In-flight RPC calls fail when a socket misses a pong, even with transient connection retries enabled; missed pongs no longer invoke onTransientError. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Schema v4 is a new implementation with faster parsing, class-based schemas, make constructors on every schema, and effectful decoding with services. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Accepts a single concrete brand identifier; apply it repeatedly to compose distinct brands. Brand identifiers are type-only and are no longer stored in AST annotations or preserved by SchemaRepresentation. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Requires the constructor's sole brand key; apply it repeatedly to compose distinct brands. For enum brand keys, pass the enum member instead of its string value. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- No longer preserves brand identifiers; reapply Schema.brand after rebuilding a representation when a branded TypeScript type is required. Also preserves ordering of equal-priority union members sharing an AST in JSON and string-tree codecs. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Array, Chunk, Effect, and Record separate helpers now return successes before failures; swap tuple order from the previous `[failures, successes]` order. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- TypeScript 5.9 or newer is required; TypeScript 7 is recommended. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Replaces verifyLosslessTransformation; existing callers must update to the new name. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- @effect/vitest and @effect/doctest require Vitest 5. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

### Security

- Sensitive query values and URL credentials are redacted in spans, request inspection, and errors without changing URLs sent over the wire. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds middleware that decompresses gzip and deflate request bodies, limits decompressed size, and rejects other codings with 415. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- The shared connection is held for the entire statement or stream, preventing another fiber's transaction from rolling back an acknowledged write or exposing uncommitted rows to a plain read. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Fixes decoding of B3 debug and legacy sampling values and rejects all-zero W3C trace and parent IDs. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)

### New APIs and options

- Adds an option for discarded child workflows; detached children neither wake their parent on completion nor get interrupted with it. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds GNU-style flags with optional values: a bare flag uses the given value, while an explicit value must be attached with `=`. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Supports per-request URLs supplied as a function of context and operation or as an Effect<string>; GraphQLResolver batches lookups by URL. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds gzip and deflate request body compression. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Supports per-request URLs supplied as a function of context and operation or as an Effect<string>; GraphQLResolver batches lookups by URL. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Enables opt-in gzip compression for built-in OTLP JSON and protobuf exporters. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Built-in OTLP JSON and protobuf exporters support opt-in gzip compression through the compression option or OTLP compression environment variables; defaults remain uncompressed. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Resolves a relative path beneath a root and returns Option.none() for traversal escapes and rooted inputs using platform path rules. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds an API for checking whether a URL parameter name is redacted. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds an API for explicitly redacting URL parameters. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds an API for explicitly redacting URLs. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Adds an SSE decode option that dispatches named events with no data line, supporting protocols such as graphql-sse. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds experimental GraphQL support with typed operations, middleware, HTTP and subscription transports, partial results, serializable errors, and cursor pagination. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds a hosts file parsing utility. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds a host conversion utility. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds a host conversion utility. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Allows configuring Scalar's preferred authentication security scheme without a TypeScript cast. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds a request-scoped HTTP layer for serverless hosts; each POST uses an MCP server owned by that request, with only sessionless protocol adapters supported. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Adds loopback address support. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- TLS socket upgrades accept an explicit client servername without changing hostname behavior when it is omitted. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- The deferred mode lets callers using disableToolCallResolution return model-generated tool calls with unknown parameters, including invalid parameters and undeclared tool names; strict validation remains the default. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Exported terminal-cell width measurement using the same logic as built-in CLI help and tables. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Separate migration and storage layers allow applications to use tables migrated by an owner connection. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Interrupts opted-in RPCs as soon as entity termination starts; persisted requests resume under the next owner without saving an interrupt reply, and server-side Uninterruptible takes precedence. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds PowerShell CLI completions using powershell or its pwsh alias. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Now accepts an optional format option; the default is a lowercase hyphenated UUID string, while bytes returns a 16-byte Uint8Array. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Now accepts an optional format option; the default is a lowercase hyphenated UUID string, while bytes returns a 16-byte Uint8Array. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds UDP support on Node, Bun, and Deno. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Added a constructor for DNS name server inputs. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Accepts address inputs; platform DNS services also accept name server inputs, and Dns.nameServerFromInput is added. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds experimental Host, Dns, and AddressResolver modules with Node, Bun, and Deno services for host parsing, DNS queries, and endpoint resolution; services must be provided explicitly. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds fromInput constructors to the effect/net data types. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds TLSA records and Schema.DnsTlsaRecord; Node.js queries them with resolveTlsa on Node.js 22.15 or 23.9 and later, while other listed runtimes return Unsupported. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Accepts a position option for concurrent reads that leave the cursor unchanged. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Accepts a position option for concurrent reads that leave the cursor unchanged. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- The noFollow option rejects symlinks at the final path component; it is supported on Node and Bun on POSIX, while Windows and Deno return BadArgument. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Setting allowSubscriptions to false disables v2026_07_28 subscriptions while keeping request-scoped progress and log notifications. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds conversion for runtime-reported addresses. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- The delay option postpones an element's first delivery in the memory, Redis, and SQL stores. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds onPingTimeout to distinguish ping timeouts from other socket failures; it runs before onDisconnect and in-flight call failures when a ping timeout drops an open connection. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds onPingTimeout to distinguish ping timeouts from other socket failures; it runs before onDisconnect and in-flight call failures when a ping timeout drops an open connection. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Exports exact JSON Schema integers bounded by JavaScript's safe integer limits; composed bounds retain tighter constraints and exact integer branches preserve oneOf. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Adds stderr terminal detection with an overridable false default and runtime detection for Node.js, Bun, and Deno. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Provides deterministic random operations derived from a seed while preserving a platform crypto service's digest implementation. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Node and Bun clients can send handshake headers alongside subprotocols through socket constructors, channels, and layers; browser-compatible constructor calls are preserved when headers are absent. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- This opt-in option for McpServer.layerHttp lets DELETE end a session and interrupt active requests; later requests with that session id return 404. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- More atom registry APIs are exposed. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- DecisionModel.decide accepts image input; providers opt in with `supportsImages: true` and receive images through `ProviderOptions.images`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Anthropic input-token usage now includes cached tokens, with cache reads and writes reported in separate usage attributes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Completion-handler services, including optional handlers, are included in the requirements. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- RPC socket clients gain a configurable ping interval; the default remains five seconds and any decoded server frame counts as liveness. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- RPC socket clients gain a configurable ping timeout; the default remains five seconds. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Image input is passed to supporting providers through this option; unsupported models reject nonempty image input. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Schemas returned by this API expose the selected tag property key through `tag`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Schemas returned by this API expose the selected tag property key through `tag`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- SQL statement span-naming rules are exported through Statement.spanName and Statement.spanTarget. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- SQL statement span-target rules are exported through this API. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Providers can opt in to image input by setting `supportsImages: true`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Types now accept callbacks that select a TTL from the computation's Exit, including piped calls. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Adds an optional capability query for support of system messages in conversation history, with scoped overrides; Anthropic system instructions are preserved. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Services are now defined with Context.Service. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available; Node, Bun, Deno, and browser packages provide the platform Crypto service. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A durable queue is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds EmbeddingModel, the DecisionModel classification and rating API, dynamic tools, and tool approvals. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Models network addresses. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds full Deno support. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds SSR hydration, stale-while-revalidate atoms, and serializable RPC and HttpApi queries. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Software transactional memory is built into Effect.tx, with TxRef and related transactional data types. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- HTTP modules add graceful server shutdown. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Supports typed response headers, streaming and SSE responses, and the HTTP QUERY method. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds in-memory testing for HttpApi. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- The browser package adds IndexedDB support. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Supports protocol versions 2024-11-05 through 2026-07-28, including elicitation, sampling with tools, resource subscriptions, and typed tool output. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Can be configured with standard OpenTelemetry environment variables. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- HTTP modules add rate-limited clients. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- HTTP modules add response compression. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Provides a compact binary codec and is the default wire format for cluster transports. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Powers JSON Schema import and export, TypeScript code generation, and AI structured output. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- A new module is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Runner memory can be bounded with ShardingConfig limits. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Exposes structured reasons such as UniqueViolation. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- HTTP modules add static file serving. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds succeedEffect, failEffect, and verifyRoundTripEffect so assertions can use the calling Effect's services, test clock, and interruption; the module and its public APIs are unstable. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Workflows can be declared with class syntax. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- An in-memory workflow engine is available. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

### Performance

- Caches the last response decoder for each response kind, keyed by validation mode and ordered tool schema identities. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Reduces statement overhead by borrowing the shared connection while preserving semaphore exclusion and failed-COMMIT recovery. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Optimized for picking zero or one service. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Fixes quadratic parsing time for long lines split across many chunks. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Fixes quadratic parsing time for long lines split across many chunks. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- The Kubernetes service-account token is cached for one minute so rotated credentials are picked up without reading the token file on every request. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Caches per-tool response schemas and parameter-mode copies to reduce schema construction. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- JIT and AOT decoding of transformations whose source has checks is faster; compiled TemplateLiteral validation enforces oneOf parts and preserves interpreter diagnostics in transformation chains. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Resolves candidate parsers once per union instead of on every decode, reducing allocations and improving decoding and encoding speed. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

### Behavior and default changes

- Span names use only the entity type to stay low-cardinality; the entity ID remains in the entity.id attribute. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Stores attempt metadata; yield it inside a transaction body to read attempt, retryReason, and schedule-like timing fields. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Colliding numeric, length, item-count, and property-count bounds are tightened in place rather than moved into allOf; redundant same-side bounds are dropped. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Wakes a suspended caller as soon as its workflow has a final result instead of waiting for the next retry schedule step; a replay that suspends again does not spend a step. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- The passed effect counts as in-flight work, so a parked sibling no longer suspends the run while it executes. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Interrupted server-to-client requests now send MCP cancellation notifications instead of internal RPC control messages. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- CLI prompts and the command wizard respect NO_COLOR by suppressing color and style escapes while preserving cursor and redraw controls. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- JSON logs and Node inspection serialize SchemaError as a compact object with its tag and formatted message instead of schema AST nodes. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Shutdown hands off shards one at a time after entities and singletons stop; handoff waits are bounded, and shutting-down runners no longer acquire shards. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Input is acquired only when a prompt needs it, leaving piped stdin untouched for constant fallback prompts. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- The result type now includes runtime layer errors. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- For non-object failures, the internal stack frame is no longer captured; the stack contains the message and span frame when available. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Batches of at least two statements are named BATCH or BATCH {target}, with `db.operation.name` set to BATCH and `db.operation.batch.size` recorded. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- HTTP tracing, logs, traces, and resources are aligned with OpenTelemetry conventions; homogeneous primitive arrays export as array attributes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- SQL tracing records Effect execution methods here instead of in `db.operation.name`. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- HTTP tracing aligns span names, response error status, server addresses, and ports with OpenTelemetry conventions; header capture is opt-in. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- LanguageModel spans are client spans and record `gen_ai.output.type` as `text` or `json` for every provider. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Default span names are now RPC methods, such as Echo.Ping rather than RpcClient.Echo.Ping; set spanPrefix to retain the old names. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Client and server spans set their respective span kinds and record `rpc.system.name` as effect_rpc and the `rpc.method` attribute; user spanAttributes still override these. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Modules and directly importable exports receive explicit stability tags; stable follows strict semver and unstable may break in minor releases. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Helpers now allow interruption while waiting for locks, while preserving automatic release after acquisition. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Helpers now allow interruption while waiting for permits, while preserving automatic release after acquisition. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Schedules pause while aggregation is idle; when a schedule ends, the current aggregation is emitted and sink leftovers are drained without further upstream pulls. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Separates wall-clock time from monotonic time. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Effect 4.0 is the first stable release of v4, replacing the beta and release-candidate series. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Aligns logs and spans with the OpenTelemetry specification. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Becomes schema-aware and supports server-originated requests and notifications. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Has a pull-based reader with backpressure and STARTTLS support. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

### Tooling

- Becomes a native property-based testing module and no longer depends on fast-check. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Adds global flags, command aliases and examples, an interactive wizard mode, and Bash, Zsh, and Fish shell completions. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

### Fixes and other changes

- When the input is a mutable array, the onNonEmpty callback receives a NonEmptyArray. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Failures now carry the combined record or tuple as previousSuccess instead of a single input's value. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Late reads of uninitialized dependencies no longer cause infinite atom rebuilds. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Deferred callback wakes are no longer lost when an activity suspends while a parallel activity is running. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Expanded values are no longer rescanned; self and circular references do not overflow, escaped references stay literal, and defaults apply to empty expansions. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Expanded values are no longer rescanned; self and circular references do not overflow, escaped references stay literal, and defaults apply to empty expansions. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Conversions handle very large millisecond values without throwing, compare equal to nanosecond equivalents, and preserve nanosecond precision for large integer millisecond values. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Waits for filesystem watcher installation and all GraphQL watch subscriptions, including nested directories, before generating so startup edits are not missed. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Accepts Redacted values as URL parameters. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Handler-local request.url is corrected for parameterized and percent-encoded prefixes, respecting duplicate-slash configuration. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Interruptions no longer call Math.random and hashing defects, preventing deterministic hosts that forbid randomness from looping forever or overflowing the stack. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Tool approvals are collected once per request instead of twice. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Persisted local replies are recovered from storage to prevent requests hanging when replies arrive before handler registration; terminal in-memory publication waits for the outer transaction to succeed. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Array and variadic tuple patterns narrow only the matched prefix, leaving remaining elements with their original type. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Preserves completion-handler service requirements in URI templates when handlers take a context argument. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Preserves completion-handler service requirements in URI templates when handlers take a context argument. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Healthy connections are no longer closed before a ping when its tick runs late; slow requests stay connected while the server responds. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Decoding stays synchronous when a decoding default is an already-successful effect such as Effect.succeed(...). (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- CR and CRLF line endings in event data now start a new data line, like LF, preventing data from being dropped after a lone CR. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer hangs when an async iterator's pending next() never settles. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer hangs when an async iterator's pending next() never settles. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Does not call a custom transform for input without words, such as an empty string or `---`. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer throws on trailing underscores or even-length underscore runs; trailing underscores are dropped and even-length runs return an empty string. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer throws on trailing underscores or even-length underscore runs; trailing underscores are dropped and even-length runs return an empty string. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Interrupted sleeps are removed and new sleeps are inserted in order instead of re-sorting the queue. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer skips sleeps registered by a woken fiber after more than one scheduler hop. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- No longer skips sleeps registered by a woken fiber after more than one scheduler hop. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- 64-bit trace IDs are padded to 128 bits in OTLP exports and traceparent headers. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Accepts Redacted values as URL parameters. (4.0.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.5)
- Outgoing cluster messages are persisted while the locally assigned shard is waiting for its lock. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Fixes startup accessing storage-loop state before initialization, avoiding a scheduler-dependent ReferenceError and delayed initial storage reads. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Zoned additions apply hours, minutes, seconds, and milliseconds as elapsed time across DST transitions. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Zoned subtractions apply hours, minutes, seconds, and milliseconds as elapsed time across DST transitions. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Releases durable waits from losing branches when the race settles, so late completions no longer preempt and replay the continuing workflow. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Generated clients use decoded response aliases and render bare numbers with a standard leading finite check as Schema.Finite, preserving annotations and other checks. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Honors the Retry-After response header when retrying transient failures. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Correctly reads a Retry-After HTTP date instead of treating it as a number of seconds. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Interrupts a streamed response body when its request is aborted after headers are sent, even if the body is no longer being read, releasing the request scope. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Merges outer headers and cookies into a copy of a raw Response, leaving original headers unchanged and preventing cookies from accumulating across reused responses. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Fixes persistence failures for uploads named . or .. and for long multi-byte file names. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Keeps streamed text and reasoning in stream order and preserves partial text from unended text blocks. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Grouped resolvers no longer retain batch keys for their lifetime; keys are dropped when their batch stops pending, including after interruption. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Stops at the matching element and returns the remaining input as leftovers instead of dropping the element after a match. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Stops at the matching element and returns the remaining input as leftovers instead of dropping the element after a match. (4.0.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.4)
- Orphaned activity requests now receive Suspended instead of waiting indefinitely for replay registration. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Persisted requests deliver terminal replies only after commit or clean rollback; on transaction failure, they recover a committed reply or retry the request. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Workflow branches continue after recording a result instead of stalling until a concurrently parked sibling is woken. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Returns Some for infinite nanosecond totals instead of None. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Infinite nanosecond totals now return an infinite duration instead of throwing. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Multiplying a nanosecond-backed duration by fractional or non-finite numbers no longer throws; fractional results round to the nearest nanosecond. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Synchronous re-entry no longer causes crashes or premature interruption in cached effects. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Request-path normalization now preserves duplicate slashes in query values. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- OTLP exporters retain all finite boundaries and overflow observations; Prometheus emits a single +Inf bucket. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Waits for the reported reset once a response's remaining budget is exhausted, including when a limit header is also present. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Interrupted activities can run again when replaying a preempted execution. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Cancellation that withholds every reply returns an empty 200 text/event-stream response; other request POSTs ending without a response return 500. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- WithTransaction RPCs save typed failures and non-fatal defects after rollback so retries receive the stored reply; successful replies still commit with handler writes. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Encoding failures are reported to ErrorReporter, and client defects include the RPC tag. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- When response encoding fails, the span ends with the encoding defect instead of recording a client interruption. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Exports exact JSON Schema integers bounded by JavaScript's safe integer limits; composed bounds retain tighter constraints and exact integer branches preserve oneOf. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Shard handoffs now propagate interrupts and stream acknowledgements to draining requests, accept acknowledgements after client EOF, and wait briefly to serve volatile requests during handoff. (4.0.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.3)
- Property checks, schema generation, and shrinking now propagate defects and interruptions accompanying typed failures, while removing typed failures from mixed causes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The data-last overload now correctly infers a changed success type. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- This API no longer throws when `window` is undefined. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Writing search parameters now preserves the URL hash and omits empty query strings. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- This API no longer throws when `window` is undefined. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Result types are corrected for union response modes while omitted mode continues to produce decoded-only results. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- An interruption race no longer leaves an abandoned lookup running or its key stuck in the cache. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Resources are no longer leaked when interrupted during acquisition. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Options are derived from the TextDecoder constructor so declarations work with Node-only types without requiring the DOM library. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Concurrent flatMap no longer drops inner scope finalizer defects; usage and release failures are both preserved. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The data-last overload now preserves channel requirements and adds the mapping function's requirements. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- A side finalizer failure no longer causes merge to hang or succeed; usage and finalizer failures are both preserved. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Inner scope finalizer defects are no longer dropped; usage and release failures are both preserved. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The returned Effect now includes the channel's error type. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Record values now preserve separators, including base64 padding in OTLP headers. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Repeated DST intervals no longer produce past occurrences or exhaust the search limit. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Throwing error mappers become defects instead of escaping asynchronous callbacks and leaving fibers suspended. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Finalizer defects are preserved. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Finalizer defects are preserved. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Fallback steps preserve errors and service requirements from layers, predicates, and schedules; captured services are provided to schedules. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Redaction handles getter-returned values with toJSON without invoking getters twice. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Single-value array fields are now accepted in form-urlencoded and GET payloads. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Result types are corrected for union response modes while omitted mode continues to produce decoded-only results. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Unread responses are no longer retained on runtimes without FinalizationRegistry, such as Hermes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Cookies can now be read on platforms whose Headers lacks `getSetCookie`, such as React Native. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- For successful WebSocket upgrades, server middleware now receives status 101 rather than the discarded handler response status. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Server spans are marked failed for 5xx responses, including rendered errors, without changing the application exit or existing span failure causes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The serve service now infers required services from the middleware-transformed app. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Retries defer each build until execution instead of returning an already-finalized resource. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- retryPolicy is now forwarded through this layer. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Shutdown finishes in-flight output before flushing remaining entries, without overlapping flushes. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Disposal no longer deadlocks when called from one of the runtime's own fibers, including child fibers. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- McpServer.layerHttp uses the negotiated protocol version when a session request omits this header; invalid or mismatched protocol requests return JSON-RPC error bodies. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Completion-handler services, including optional handlers, are included in the requirements. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Queue.clear no longer swallows failures combined with Cause.Done. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Interrupted queue operations at a scheduler yield no longer lose messages. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Many equal requests sharing a pending cache entry no longer cause a stack overflow. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Successful pipeline results are returned instead of failing with a channel completion signal. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Passing `spanPrefix: "RpcClient"` or `spanPrefix: "RpcServer"` retains the former default RPC span names. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The sink's unconsumed elements are no longer dropped from a partially consumed chunk. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Overlapping windows no longer drop elements from the final partial window. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Sink failures after end-of-stream are no longer swallowed, and the stream no longer hangs when the sink finishes during an upstream pull. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- The stream no longer hangs when an input completes without emitting. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Immediate opening CRLF is trimmed in basic and literal multiline strings, matching existing LF handling. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- One-shot iterable inputs are preserved across transaction retries. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- Block scalar chomping preserves trailing line breaks with keep indicators and avoids adding line breaks to empty or unterminated scalars. (4.0.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.2)
- A fiber's context is preserved when another fiber wakes or interrupts it; Effect.tryPromise error handlers run in the resumed fiber's context. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Recovery replays unfinished requests without duplicating requests awaiting first dispatch; shutdown interrupts waiters, and superseded rebuilds cannot publish stale handlers or SQL lock connections. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Reset rows are locked in message order to prevent PostgreSQL deadlocks between message claims and shard or address resets. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Entity registration is prevented if shard ownership is lost during construction, and pending requests retry on the new owner. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Returns consistent shard assignments for the same nodes and weights regardless of add/remove history; fractional weights or hash ties may have different assignments. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Client-abort-only request causes are logged as "Sent HTTP response" instead of interrupt errors, while response status annotations and logging of other causes are preserved. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Invalid requests no longer report schema errors as server failures. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Honors If-Range by returning the full file for stale or weak entity-tags; date validators are rejected because filesystem metadata cannot establish their strength. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Optional MCP fields whose schemas decode to classes now encode correctly. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Valid expressions whose RegExp source is canonicalized are imported correctly, including slashes, empty patterns, and literal line terminators. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Idle subscriptions stay open on Cloudflare Workers by using SSE keepalives. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Usage TTL now expires only idle, unreserved excess items, oldest idle first; idle time is measured from the last release. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Shutdown drains responses after stdin reaches EOF. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Stream interruption no longer leaves chunk delivery blocked on a full buffer and stalling the shared protocol receive loop. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Only requests pending when an error broadcast begins receive that error; requests started synchronously by error handlers remain pending for their own responses. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Entry expiry is set before lookup waiters wake, preventing reuse of a zero-TTL result. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Refreshes no longer release shards acquired while the refresh is in flight. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Reassignment no longer durably cancels outstanding RPC requests. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Preserves server and client extension capabilities. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Emits its initial state for empty streams. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- The shape strategy retains token debt after early wake-ups and uses monotonic time so wall-clock changes do not affect throttling. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Decode failures stay local to the affected request and interrupt it on the server, without disconnecting unrelated requests. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Pending interruptions are preserved when an uninterruptible effect fails; typed failures are dropped when interruption skips recovery handlers, while defects remain. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- Preserves milliseconds for pre-epoch timestamps on runtimes that omit Intl fractional seconds. (4.0.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.1)
- A stale finalizer no longer evicts a newer cached atom. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Concurrent calls no longer lose synchronous successes or failures. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Union-of-tag inference now reflects the selected RPC payloads and results instead of resolving to never. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Union-of-tag inference now reflects the selected RPC payloads and results instead of resolving to never. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Cause has a flat structure. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Custom message storage implementations must honor the optional expected reply ID to prevent stale concurrent workflow resumes from clearing a newer completed reply. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- All Effect packages share one version number and are released together; use the same version of effect and every @effect/* package. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Preserves sibling and callback cleanup failures alongside interruption in concurrent execution, including shared Layer.build. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Preserves sibling and callback cleanup failures alongside interruption in concurrent execution. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Interrupts losing effects when the race settles or is interrupted while other effects are still starting. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Interrupts losing effects when the race settles or is interrupted while other effects are still starting. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Interrupts losing effects when the race settles or is interrupted while other effects are still starting. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Interrupts losing effects when the race settles or is interrupted while other effects are still starting. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- The effect package has no runtime dependencies. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Union-of-tag inference now reflects the selected RPC payloads and results instead of resolving to never. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Retain the handler's failure exit through response handling and middleware. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- No longer retains previously used equal object keys after replacement or removal, including when Cache and ScopedCache refresh entries on hits. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- The interrupt fiberId type admits `null` emitted by JSON encoding; consumers should handle `null` alongside `undefined`. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Decoded and encoded schema representations no longer contain duplicate references when schemas are reused through optional or mutable keys. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- No longer loses parent checks when projecting checked children without transformations; suspended children remain opaque and structural checks are preserved. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- No longer loses parent checks when projecting checked children without transformations; suspended children remain opaque and structural checks are preserved. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Preserves the grouping of branded union types in generated TypeScript code. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Server WebSockets close with 1000 on success, 1001 on interruption, or 1011 on failure, while preserving explicit close codes. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)
- Failed workflow runs retry resets instead of acknowledging deferred completion before the run resumes. (4.0.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%404.0.0)

## effect 3

### Breaking changes

- Preloaded references are released after acquisition so entries follow their idle TTL; preloading is skipped when the idle TTL is zero, and setting idleTimeToLive to Infinity keeps entries for the map's lifetime. (3.22.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.3)
- Wraps to the first matching day of the next month when a later matching day does not exist in the current month, preventing earlier matches from being skipped. (3.21.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.5)

### Security

- Effect `AsyncLocalStorage` context lost/contaminated inside Effect fibers under concurrent load with RPC (3.20.0) — [security advisory](https://github.com/advisories/GHSA-38F7-945M-QR2G)

### Deprecations

- Deprecates Graph.neighborsDirected. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)

### New APIs and options

- Adds Graph.successors for querying graph successors. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Adds Cron.prev and reverse iteration support, aligning next/prev lookup tables and fixing DST handling symmetry. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Adds Effect.currentPropagatedSpan. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Adds type-level utilities for asserting layer types. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Types.VoidIfEmpty is backported to 3.x. (3.20.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.0)
- Adds the typeConstructor annotation for Schema. (3.19.13) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.13)
- Introduces JsonValue and uses it in JsonSchemaAnnotations to improve type safety for schema examples and defaults. (3.19.11) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.11)
- Adds options for selecting the target JSON Schema version in the make function. (3.19.11) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.11)
- Adds the RcRef.invalidate API. (3.19.6) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.6)
- Adds an experimental concurrency primitive that shares permits across keyed partitions and distributes waiting permits fairly using a round-robin strategy. (3.19.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.4)
- Adds Effect.fn.Return to allow typing returns on Effect.fn. (3.19.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.0)
- Adds an experimental HashRing module. (3.19.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.0)
- JSON Schema generation adds jsonSchema2020-12 as a target. (3.18.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.18.5)

### Performance

- Uses a linear matcher when decoding template literals containing only string spans. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- Prevents multiple iterations over the same Iterable. (3.19.8) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.8)
- Prevents multiple iterations over the same Iterable. (3.19.8) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.8)
- Backports an optimization to Effect.gen. (3.19.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.5)
- Merged layers can now be finalized in parallel. (3.19.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.1)

### Behavior and default changes

- Fibers spawned by Effect.timeout no longer log unhandled errors. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- The idleTimeToLive option can now be a function receiving the key and returning a duration, allowing different TTL values for different resources. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Builds synchronously when possible, so creating a ManagedRuntime may no longer require asynchronous execution. (3.19.19) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.19)

### Fixes and other changes

- Prevents interrupted acquisition from causing an uninterrupted scope closure to fail. (3.22.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.3)
- Prevents interrupted acquisition from causing an uninterrupted scope closure to fail. (3.22.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.3)
- Fixes Reloadable.auto hanging when its scope closes. (3.22.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.3)
- Fixes the use of Schema.NonEmptyArrayEnsure with strings. (3.22.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.2)
- Fixes erroneous clearing of the entire bucket on hash collision. (3.22.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.2)
- Fixes erroneous clearing of the entire bucket on hash collision. (3.22.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.2)
- Avoids collisions between JSON key paths. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- Fixes zero-capacity rendezvous behavior for take and takeN. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- Fixes termination with bounded dropping and sliding buffers. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- Errors from wrapped config parsers are redacted. (3.22.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.1)
- Fixes graph algorithm edge cases around reversal. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Fixes graph algorithm edge cases around shortest-path weight validation. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Fixes graph algorithm edge cases around strongly connected components. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Fixes graph algorithm edge cases around topological sort initials. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Fixes graph algorithm edge cases around undirected edge queries. (3.22.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.22.0)
- Fixes parsing and scheduling edge cases involving whitespace, Sunday 7, strict numeric tokens, explicit full day ranges, and month-constrained day-of-month / weekday matching. (3.21.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.5)
- Cron fields like 5/15 now expand from the starting value through the field maximum. (3.21.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.5)
- Fixes behavior when the test clock is adjusted to infinity. (3.21.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.5)
- Graph traversal and shortest-path algorithms now traverse undirected edges independently of their stored source/target orientation. (3.21.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.4)
- Records with string keys and Schema.Never values now emit additionalProperties: false. (3.21.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.3)
- Fixes generic type parameter inference inside $match arms. (3.21.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.3)
- Fractional millisecond instants are floored before conversion to BigInt. (3.21.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.2)
- Batched request resolver defects no longer leave request Deferreds incomplete and consumer fibers hanging forever. (3.21.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.1)
- Fixes Effect.annotateCurrentSpan. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Logs are now added to the first propagated span in the described Effect.fn and withSpan case. (3.21.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.21.0)
- Fixes a crash when comparing null values inside structuralRegion by guarding Object.getPrototypeOf calls. (3.20.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.1)
- Avoids using a class for PrettyError so error.name is preserved. (3.20.1) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.1)
- getPropertySignatures no longer throws on structs containing optionalWith variants that produce Transformation nodes. (3.20.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.0)
- Scheduler task draining now isolates AsyncLocalStorage across fibers. (3.20.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.0)
- Schema.omit now handles structs combining optionalWith transformations and index signatures without returning the wrong AST result. (3.20.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.0)
- Post-rest validation now checks each tail index sequentially. (3.20.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.20.0)
- Fixes a race condition that could leak permits. (3.19.19) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.19)
- Stream.changes no longer writes empty chunks. (3.19.18) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.18)
- Correctly handles multi-byte UTF-8 characters split across chunk boundaries. (3.19.17) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.17)
- Handles null and undefined when matching nullable union types, preventing crashes. (3.19.16) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.16)
- Handles null and undefined when matching nullable union types, preventing crashes. (3.19.16) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.16)
- Fixes type inference loss for complex nested structures, including unions of Effects with contravariant requirements. (3.19.15) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.15)
- Fixes the Config.orElseIf signature. (3.19.15) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.15)
- Fixes plain object comparisons in structural mode. (3.19.15) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.15)
- Effect.retry now respects the times: 0 option by checking explicitly for undefined instead of using a truthy check. (3.19.14) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.14)
- Uses performance.now only when it is available, avoiding reliance on an unavailable API. (3.19.12) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.12)
- Filters invalid non-JSON values, including BigInt and cyclic references, to prevent infinite recursion on cycles. (3.19.11) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.11)
- Prevents crashes when Hash and Equal are used with an invalid Date object. (3.19.10) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.10)
- Fixes NoSuchElementException instantiation in fastPath. (3.19.10) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.10)
- The arbitrary generator for BigDecimal now allows negative scales. (3.19.9) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.9)
- Fixed the batch size behavior for SqlPersistedQueue. (3.19.7) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.7)
- Fixes DeepMutable mapping over functions. (3.19.4) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.4)
- Config error messages use the standard formatting function. (3.19.3) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.3)
- Ensures the state transition is atomic. (3.19.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.2)
- Preserves context order when merging layers. (3.19.2) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.2)
- Improves the Array.window signature. (3.19.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.0)
- Backports updates to the Graph module. (3.19.0) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.19.0)
- AsEffect is now computed. (3.18.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.18.5)
- For undirected graphs, returns the other endpoint instead of the queried node when queried from an edge's target side. (3.18.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.18.5)
- Fixes tuple output for JSON Schema 2019-09 and OpenAPI 3.1. (3.18.5) — [release notes](https://github.com/Effect-TS/effect/releases/tag/effect%403.18.5)