effect@4.0.0-rc.116

Patch Changes

• #7908 c19c63f Thanks @gcanti! - Add experimental JIT and AOT schema compilers that work through the existing
  SchemaParser APIs and share a decoder registry. Enable JIT globally with
  effect/unstable/schema/SchemaJITCompiler/enable, selectively with
  SchemaJITCompiler.enable(ast), or install generated AOT decoders without
  requiring dynamic function construction. The new
  effect/unstable/schema/SchemaAOTCompiler/Build entrypoint discovers direct
  Schema exports from explicit module loaders and writes a self-installing AOT
  module through Effect's FileSystem and Path services. Compiled decoders can
  provide optional synchronous decode and make operations; normal
  SchemaParser calls consume them transparently and retain decodeEffect and
  makeEffect as the detailed fallbacks. AOT targets declare the operations to
  prepare, so generated modules contain only those operation families and use
  the interpreter if an omitted operation is later called.

  Breaking changes

  SchemaGetter.Getter is now a tagged union that distinguishes synchronous,
  optional, and effectful transformations. Getter values now expose only pipe.
  Use the dual SchemaGetter.map, SchemaGetter.compose, and SchemaGetter.run
  functions instead of the former methods. Keeping these operations standalone
  lets bundlers remove composition code when an application does not use it.

  The public Getter constructor is removed. Use
  SchemaGetter.transformOptionalEffect instead of new SchemaGetter.Getter.
  SchemaGetter.onSome and SchemaGetter.onNone are also removed. Use
  transformEffect for an effectful transformation of present values and
  transformOptionalEffect when the transformation handles missing values.

  Transformation#compose is replaced by the dual standalone function
  SchemaTransformation.composeTransformation. Replace first.compose(second)
  with SchemaTransformation.composeTransformation(first, second) or
  SchemaTransformation.composeTransformation(second)(first).

  SchemaTransformation.make is renamed to
  SchemaTransformation.makeTransformation. SchemaTransformation.Transformation
  and SchemaTransformation.Middleware now implement Pipeable, so both values
  can be passed through standalone combinators with .pipe(...).

  SchemaAST.Context.constructorDefault now stores the constructor-default
  Effect directly instead of wrapping it in a SchemaAST.Link. Constructor
  defaults apply only during construction, so the direct representation avoids
  giving them encoding semantics and lets construction reuse already-completed
  synchronous Effects. Code that constructs or inspects SchemaAST.Context
  should pass or read the default Effect directly.

• #8287 8cb0a4f Thanks @tim-smart! - Add Decision and DecisionModel to effect/unstable/ai for batched classification, rating, and probability estimates over schema-encoded input.

• #8221 8f420bb Thanks @gcanti! - Add Arbitrary.array(item, { minLength, maxLength }) for variable-length arrays of custom Arbitraries. Shrinking removes blocks of commands while preserving the remaining values and their order, and also simplifies individual elements.

  Schema-derived arrays now also try removing prefixes and interior blocks. Shrinking composed values and Schema objects preserves child candidates that were previously lost when exploring another branch.

  Shrunk results and replay paths may change from earlier native releases. Re-run affected properties to obtain new replay tokens, and preserve important failing inputs as regression tests.

• #8233 1393080 Thanks @gold-beyond! - Add Crypto.randomULID to generate ULIDs from the current Clock timestamp and cryptographically secure random bytes.

• #8256 ccae354 Thanks @tim-smart! - Align the Effect and Stream APIs and fix several Stream type signatures.

  • Effect.orElseSucceed now passes the error to the fallback function, matching Stream.orElseSucceed.
  • Effect.isEffect narrows to Effect<unknown, unknown, unknown> instead of any.
  • Stream.bind, Stream.bindEffect and Stream.let allow re-binding an existing field and produce the same record type as their Effect counterparts.
  • Stream.Success, Stream.Error and Stream.Services are unconstrained and distributive like the Effect versions.
  • Stream.partition returns [passes, fails] and takes a capacity option, matching Stream.partitionQueue and Stream.partitionEffect. Its default capacity remains 16.
  • Stream.mapBoth takes onElement / onError, matching Stream.tapBoth.
  • Stream.scan and Stream.scanEffect take a lazy initial state.
  • Stream.catchTags rejects unknown tag keys like Effect.catchTags.
  • Fixed the data-first overloads of Stream.runIntoPubSub (error type was dropped), Stream.cross (swapped type parameter names) and Stream.mapAccumArray (onHalt return type).
  • Added Stream.as, Stream.tapDefect, Stream.tapErrorTag and Stream.unwrapReason.
  • Stream concurrency options use the Types.Concurrency alias, and JSDoc categories were consolidated across both modules.

• #8235 553c403 Thanks @tim-smart! - Retain durable deferred completions received before a workflow owner's first local run so replay can complete while the deferred reply is still being persisted.

  Keep pending completions in a cache keyed weakly by cluster activation. Handler rebuilds retain completions, and overlapping activations cannot clear each other's results. Results can be collected once their activation scope becomes unreachable; closing a scope alone does not guarantee collection.

  Release RPC stream and queue consumers when their request write fiber is interrupted.

• #8243 45b5103 Thanks @tim-smart! - Fix lost durable deferred wake-ups when a ClusterWorkflowEngine execution suspends before its run reply is persisted. Deferred completions now wait for the current run reply before resuming, so discarded executions can replay without relying on caller retries.

• #8254 77a5612 Thanks @tim-smart! - Fix file response content types: honor the contentType option and preserve explicit headers, including MIME types set by HttpStaticServer. The default HttpPlatform.layer now infers missing content types from file extensions.

  Web file responses on the default, Node, and Deno platforms prefer explicit content types, then nonempty File.type, then the file extension.

  Removed the unused contentLength option from HttpServerResponse.file; lengths are calculated from the file and requested range.

• #8229 1076170 Thanks @tim-smart! - Fix a deadlock in the memory workflow engine when a durable deferred is completed from a finalizer in the workflow awaiting it, including DurableDeferred.into inside DurableDeferred.raceAll.

• #8206 f110af1 Thanks @tim-smart! - Fix multipart file streams hanging on body read errors and preserve error causes when persisting files.

• #8284 0045152 Thanks @tim-smart! - HttpServerResponse.toWeb now keeps a raw Response's headers and Set-Cookie values when the body is omitted (HEAD, or status 204, 205 or 304). Bodyless outer statuses keep the outer status and status text; HEAD keeps the raw Response's. Outer cookies are appended to native Set-Cookie headers instead of replacing them.

• #8202 51d4a2f Thanks @xia-chao! - Fix RcRef.make to treat idleTimeToLive: 0 like Duration.zero and "0 millis" instead of an omitted option.

• #8298 4d4c4e8 Thanks @gcanti! - Fix Schema.Redacted to wrap the transformed result of its inner schema during decoding and encoding.

• #8227 ccfe152 Thanks @tim-smart! - Release non-persisted, interruptible RunnerServer handlers and mailbox slots when callers disconnect.

  Preserve dynamic WithTransaction annotations during replay and re-delivery.

• #8261 d30a0c8 Thanks @nikhilsnayak! - Add HTTP QUERY support to clients, routers, HttpApi endpoints, and AI request metadata. Configure CORS support through allowedMethods; defaults are unchanged.

  OpenAPI 3.1 output represents QUERY through x-oai-additionalOperations, which requires consumer support for that extension. The OpenAPI generator accepts the extension and the native OpenAPI 3.2 query field.

• #8255 84fe64a Thanks @tim-smart! - Preserve literal suffixes such as :wait in /operations/:id:wait across HttpApiClient, HttpApiBuilder, and OpenAPI paths.

  Server routes without a params schema keep their existing matching for RouteContext consumers. Schemas whose keys cannot be enumerated keep the existing fallback.

• #8228 49e4b37 Thanks @lloydrichards! - Support prompt titles in McpServer.prompt and McpServer.registerPrompt.

• #8228 49e4b37 Thanks @lloydrichards! - Add an instructions option to MCP servers for initialization and discovery responses.

• #7265 a2c4154 Thanks @lloydrichards! - Add server support for MCP protocol version 2026-07-28 through 2026_07_28

• #8272 23a58c0 Thanks @fubhy! - Add NetAddress.formatHost and NetAddress.inetAddressFromHostString for socket APIs that accept numeric hosts and ports separately, preserving IPv6 scope IDs. Add NetAddress.scopeIdsFromInterfaces to build a scope map for resolving named IPv6 zones from supplied network interface entries without performing operating-system lookups.

• #8293 feef90c Thanks @gcanti! - Treat Never as an uninhabited branch during Arbitrary.schema derivation. Schemas with another finite generation path, including optional properties, unions, and empty collections, no longer fail derivation.

• #8212 755e863 Thanks @IMax153! - Restrict ByteSize.Input strings to canonical non-negative integers with recognized units, rejecting malformed literals at compile time. Parse external strings and fractional quantities with ByteSize.fromString or ByteSize.fromStringUnsafe before passing them to APIs accepting ByteSize.Input.

• #8228 49e4b37 Thanks @lloydrichards! - Honor Tool.Strict in MCP input schemas and argument validation. Strict dynamic tools require Effect schemas; raw JSON Schema is rejected at registration.

  Support identified input schemas for non-strict tools. Invalid arguments use InvalidParams on protocols before 2025-11-25 and isError: true results on newer protocols.

  Distinguish validation failures from declared handler failures. Declared failures return isError: true without structuredContent: error mode uses Error.message or schema-encoded text, and return mode uses the encoded payload. Declared failures do not produce internal-error diagnostics.

  Log and report internal failures, including defects and encoding errors, while keeping client messages generic.

  Allow Toolkit.handle to accept SchemaAST.ParseOptions for parameter decoding. Expose the Toolkit.FailureOrigin cause annotation and shared Tool.FailureOrigin type, with the same origin available in Tool.HandlerResult.failureOrigin on returned failures.

• #8269 9ad9891 Thanks @tim-smart! - Add HttpApi.ParseOptions to configure server and client codecs at the API, group, or endpoint level.

  Sse.decodeSchema and ChannelSchema.decode accept parse options, and Schema.Cause encodes reasons to their wire fields.

  SSE decoding omits absent IDs, including with default options. Use Schema.optional(Schema.String) instead of Schema.UndefinedOr(Schema.String) for IDs. With onExcessProperty: "error", declare event (default: "message") and any id, including inherited IDs.

  HttpApiSchema.StreamSse data-mode types and OpenAPI schemas now make id optional.

• #8296 0beded0 Thanks @gcanti! - Improve Schema-derived BigInt and BigDecimal arbitraries with wider magnitude, precision, and exponent coverage and numeric boundary shrinking.

  Cover intermediate magnitudes up to large one-sided BigInt bounds, handle BigDecimal bounds with widely different scales, and refine decimal counterexamples between simple values.

• #8260 2940742 Thanks @xia-chao! - Fix repeated text, json, arrayBuffer, and urlParamsBody reads in HttpServerResponse.toClientResponse for raw Web Response bodies, preserving the original response for serving.

• #8270 63c1566 Thanks @tim-smart! - Fix YAML indentless sequences, multiline scalar folding, and comments. Reject unsupported compact nested sequences (- - value) and document streams.

  Previously accepted values such as description: Use when: deploy and description: Deploy: now throw SyntaxError: YAML forbids colons followed by whitespace or end-of-value in plain scalars. Quote these values, for example description: "Use when: deploy".