This Week in Effect - 140

Effect released its weekly ecosystem update, This Week in Effect 140, detailing new modules and fixes across its TypeScript library for AI-era development. Notable additions include a GraphQL client and generator, a streaming tar codec in effect/encoding, Schema.toCodecGoJson, Semantic Versioning types with range support, and custom annotation imports for JSON Schema, alongside a Module of the Week post by Maxwell Brown on Cluster delivery covering at-most-once and at-least-once delivery and message persistence. The AI package fixes address OpenAI Responses streams not ending at data: [DONE], reasoning replay alongside tool calls in openai-compat, and Anthropic fallback model reply decoding.

Hi Effecters Welcome back to This Week in Effect, your weekly update of the latest developments in the Effect community and ecosystem. Effect is the TypeScript library for the AI era, helping developers build complex, synchronous, and asynchronous programs. One key feature that sets Effect apart is how it leverages structured concurrency to provide features such as async cancellation and safe resource management, making it easier to build robust, scalable, and efficient programs. To get started, below you’ll find links to our documentation and our guide for installing Effect. Enjoy Recent major updates: New Module of the Week https://effect.website/blog/module-of-the-week/cluster-delivery post by Maxwell Brown https://x.com/maxwellbrown , focusing on Cluster delivery . Runners crash, but with Effect Cluster your messages don't need to go down with them. This week, learn how to → Choose at-most-once or at-least-once delivery → Persist messages so they survive a crash → Reply only when the work is done Module of the Week: Cluster, Part 3 ↓ Another busy week on main , with new modules landing alongside a steady stream of fixes across the platform packages. Here are the most notable changes. - Additions : Added a GraphQL client and generator, a streaming tar codec in effect/encoding , Schema.toCodecGoJson , Semantic Versioning types with range support, and custom annotation imports for JSON Schema. Also added Path.resolveWithin for root-contained path resolution, Host helpers toFullyQualified , toRelative , parseHostsFile , NetAddress.loopbackAddresses , fromInput functions for the net data types, and CliOutput.displayWidth . Native @EffectTS https://twitter.com/EffectTS GraphQL client coming soon - Cluster & workflow : Added a detached option for discarded workflow executions. Failure-suspended workflows now stay parked until resumed or interrupted, suspended callers wake up when their workflow completes, and losing DurableDeferred.raceAll waits are released once the race settles. On the cluster side, shards are now handed off one at a time on shutdown, lease-based SQL shard lock renewal was restored, and a new annotation lets cluster RPCs be interrupted on termination. Also fixed the shards gauge after shard release. - RPC, HTTP & platform : RPC gained an onPingTimeout option, and premature socket ping timeouts and connection defects that failed synchronously started requests were fixed. Added WebSocket handshake headers alongside subprotocols and servername support in client TLS upgrades. Fixed HttpRouter prefixes with path params breaking request.url , absolute HTTP URLs in opaque-origin documents, a UTF-8 BOM breaking JSON in Node HTTP text, NodeStream hangs on premature closure, and several child process edge cases. - SQL & persistence : Exposed TCP keepalive settings in sql-pg and fixed released connection pins reaching the next borrower and inferred empty array binding. Fixed connection starvation in PGlite, the MSSQL error listener, the ClickHouse migrator ledger, Redis PersistedQueue data loss on lone-surrogate payloads and fractional Redis fixed-window rate limits. Event log replication, remote SQL journal conflicts and persistence expiry checks for reused reads were also fixed. - AI : Fixed OpenAI Responses streams not ending at data: DONE , web search actions without patterns, service tier and provider-nested error metadata, and reasoning replay alongside tool calls in openai-compat . Invalid and undeclared tool calls are now returned when validation is deferred, Anthropic replies from a fallback model now decode correctly, and the Cloudflare provider can send decision images to Clef. - Observability : Fixed several OTLP export issues: histogram overflow buckets, integers outside the int64 range, NaN and Infinity values, and batches dropped when a span has a 64-bit B3 trace id. The active span is now recorded on OpenTelemetry log records, and the DevTools client reconnects after socket failures. - Core & Schema fixes : Fixed Duration conversions and Duration.times for very large or non-integer inputs, Effect.cached under synchronous re-entrancy, Stream.timeout ending while the next chunk is pending, and atom rebuild loops from late dependency reads. Match now keeps the unmatched tail in array prefix patterns and rejects unknown keys in object patterns, Array.match exposes NonEmptyArray for mutable arrays, and Schema.Enum preserves literal member inference. Schema also rejects duplicate tagged union discriminants and merges colliding bounds in JSON Schema export instead of emitting allOf . You can follow the full changelog in the effect repository https://github.com/Effect-TS/effect/commits/main . To catch up on more updates, check out Effect v4 Updates https://www.effect.website/blog?category=effect-v4-updates , starting from the recently published Effect v4 RC: September 2026 Updates https://effect.website/blog/effect-v4-rc-september-recap . Other technical updates from the past week. - Type received and forwarded HTTP request methods as open strings https://github.com/Effect-TS/effect/pull/8766 Bug Fix, next-minor - Type Atom.Serializable encode/decode as Schema.Json https://github.com/Effect-TS/effect/pull/8763 Bug Fix, next-minor - Support duplex additional child-process file descriptors https://github.com/Effect-TS/effect/pull/8905 Feature, next-minor - Add an explicit maxDepth option to Context.makeUnsafe https://github.com/Effect-TS/effect/pull/8969 Feature, next-minor - Export HttpClient.isTransientError and isTransientResponse https://github.com/Effect-TS/effect/pull/9059 Feature, next-minor - Add pool occupancy stats to Pool, PgPool, and PgClient https://github.com/Effect-TS/effect/pull/9090 Feature, next-minor - Add request-level dependencies to McpServer https://github.com/Effect-TS/effect/pull/9154 Feature, next-minor - Fix sql : load filesystem migrations from their own module https://github.com/Effect-TS/effect/pull/9157 Bug Fix, next-minor - AI: TypeSafe images and Box questions via Decision.locate https://github.com/Effect-TS/effect/pull/9177 Feature, next-minor - Acknowledge discarded RPC calls before running handlers https://github.com/Effect-TS/effect/pull/9182 Improvement, next-minor - Fix persistence : isolate stores on KeyValueStore and Redis backings https://github.com/Effect-TS/effect/pull/9223 Bug Fix, next-minor - Fix Redis persisted queue claim ownership https://github.com/Effect-TS/effect/pull/9229 Bug Fix, next-minor - AI: TypeSafe images and Box questions via Decision.locate https://github.com/Effect-TS/effect/pull/9177 Feature, next-minor - Support duplex additional child-process file descriptors https://github.com/Effect-TS/effect/pull/8905 Feature, next-minor - Add pool occupancy stats to Pool, PgPool, and PgClient https://github.com/Effect-TS/effect/pull/9090 Feature, next-minor - Fix persistence : isolate stores on KeyValueStore and Redis backings https://github.com/Effect-TS/effect/pull/9223 Bug Fix, next-minor - Fix sql : load filesystem migrations from their own module https://github.com/Effect-TS/effect/pull/9157 Bug Fix, next-minor - Very few 2-day passes left for Effect Days 2026 https://effect.website/effect-days The conference is scheduled for December 9–11 in Livorno, Italy.I’m so happy to share that I’ve received the loveliest invitation to give a talk on @EffectTS https://twitter.com/EffectTS day My lawyers assured me that once my picture is on their page, revoking the invitation is actually illegal. See you there, and please only ask questions I know the answers to, - Effect Miami is scheduled for Nov 9. Guess who’s speaking I’m beyond thrilled to announce @EffectTS https://twitter.com/EffectTS Miami 3 — November 9 @thelabmiami https://twitter.com/thelabmiami - Wynwood 5:30 pm Three talks: - Harnessing AI models with Effect TS - Advanced Effect design patterns - Frontend architecture for agents and humans Guess who's speaking? add in comments We’ll - Effect Warsaw 2 https://luma.com/k5o7m2pg is coming up on November 17 Effect Warsaw 2 is coming next month 👉 Sam is going to talk about full stack effect. More talks, 🍕 and 🍻 coming too luma.com/k5o7m2pg https://luma.com/k5o7m2pg - A big thank you to the attendees, the organizers, and evryg https://www.evryg.com/en for hosting the Effect Paris 🇫🇷 meetup this week @EffectTS https://twitter.com/EffectTS Paris 7 is now live 🔥 And starting with @rodygosset https://twitter.com/rodygosset explaining us how Effect is a good fit for all sizes of apps First edition being recorded thanks to Inato folks, be ready for the replays 🎥Thanks to @EvrygDotCom https://twitter.com/EvrygDotCom for hosting the @EffectTS https://twitter.com/EffectTS Paris Meetup and 🍕 , and to @topheman https://twitter.com/topheman , @rodygosset https://twitter.com/rodygosset , @jbmusso https://twitter.com/jbmusso , and Swann H. for the great talks It was nice to nerd out IRL for once. - Effect Office Hours 🔥 every Wednesday at 10:00 AM ET / 16:00 CET on our YouTube channel https://www.youtube.com/@effect-ts . Visit our Effect Community Events calendar https://luma.com/effect-community and subscribe for updates on upcoming Effect events. - 📈 Every 5 times TypeScript is downloaded Effect is, that’s a lot - Huge congrats to Expand AI – built with Effect. Replying to @janbhwilhelm https://twitter.com/janbhwilhelm/status/2110406355034984474 Absolutely And yes this wouldn't have been possible without Effect. Now gotta migrate to Effect 4 cc @MichaelArnaldi https://twitter.com/MichaelArnaldi - Coming soon 👀 Effect native test runner zero dependencies achieved internally. First class effects, layers, scopes no "before/after" hooks , works everywhere node, bun, browser, etc. . Agent first. @EffectTS https://twitter.com/EffectTS - An EffectTS native ORM Been building an @EffectTS https://twitter.com/EffectTS native ORM for a while, and it's finally ready for some of you to try. - includes ClickHouse + Postgres - Fully typesafe - Migrations for both, and it can adopt your existing drizzle-kit migrations Still early, but it's been running @Mapledotdev https://twitter.com/Mapledotdev in - 💅 companies building software with @EffectTS https://twitter.com/EffectTS are miles ahead in trust and reliability without me even looking at the code - CAFE stack ☕️ Cloudflare x @EffectTS https://twitter.com/EffectTS x @foldkit https://twitter.com/foldkit Benefits of the CAFE stack @Cloudflare https://twitter.com/Cloudflare + @alchemy run https://twitter.com/alchemy run + @foldkit https://twitter.com/foldkit + @EffectTS https://twitter.com/EffectTS for building software with coding agents: 1. Agents invent less architecture. They focus on product-level execution within a well-defined architecture. You build faster, with more confidence. You - Agreed. basically every time i write typescript without effect i regret it and end up having to retcon that mistake - Yep 😎 I kinda love that people are listing “built with @EffectTS https://twitter.com/EffectTS ” as a feature for their product releases. It’s fascinating to say the least. - CAFE news https://ratstack.sh/news - By Joel. - namera https://github.com/thenamespace/namera - EVM smart-account wallets for AI agents. By The Namespace. - effect-actions https://github.com/gjermundgaraba/effect-actions - define an Effect action once and expose it over HTTP, MCP, native Toolkits, and CLIs. By gjermundgaraba. - effetch https://github.com/monarcode/effetch - schema-driven HTTP calls on top of Effect v4’s HttpClient . By monarcode. - effect-units https://github.com/rjdellecese/effect-units/ - typed quantities and unit conversions for Effect, adapted from Elm’s elm-units . By rjdellecese. - effect-platform-chrome https://github.com/yotamishak/effect-platform-chrome - Effect v4 services, RPC, and testing utilities for Chrome Manifest V3 extensions. By yotamishak. - effect-assistant https://github.com/dbrxnds/effect-assistant - build chat assistants that run tools in the background and message the user back, built on Effect and effect/ai . By dbrxnds. - effect-views https://github.com/jpowersdev/effect-views - a prototype for server-rendered HTML and schema-bound forms, built with Effect and htmx. By jpowersdev. We’re thrilled to announce Ziverge as the first Effect Adoption Partner Here are 3 things we're thrilled to announce, as part of our partnership with @EffectfulTech https://twitter.com/EffectfulTech , creators of @EffectTS https://twitter.com/EffectTS 🔥 ➡️ Ziverge will be sponsoring Effect Days ➡️ We have produced an Effect SDK for @GolemCloud https://twitter.com/GolemCloud ➡️ We've launched an @EffectTS https://twitter.com/EffectTS Training Workshop Sign up for Looking for a role where you can work with Effect? We now have a dedicated Effect jobs page featuring open roles from companies that use Effect. We’ll keep it updated as new opportunities come in. New this week: Bitfocus & Warp are hiring Effect engineers. Explore Effect job opportunities → https://www.effect.website/effect-jobs Disclaimer: Please note that these job postings are shared for informational purposes, and we encourage applicants to verify details directly with the hiring companies. Don’t forget to listen to our Cause & Effect podcast hosted by Johannes Schickling and available on YouTube https://www.youtube.com/@effect-ts , X Twitter https://x.com/EffectTS /status/2085682364315783506 , and audio platforms like Spotify https://open.spotify.com/episode/12L2neeIte6LUYQpzTh9n6 and Apple Podcast https://podcasts.apple.com/us/podcast/software-engineering-in-the-age-of-ai-10/id1781879869?i=1000780438320 . John A. De Goes, the creator of ZIO https://zio.dev/ , as well as CEO of Ziverge https://www.ziverge.com/ and Golem Cloud https://golem.cloud/ , joins Johannes Schickling and Michael Arnaldi to discuss how AI is reshaping software engineering, what developers should still learn, and why Effect’s primitives are especially valuable for coding agents. Play https://youtube.com/watch?v=irmz5X3c7Do - Effect Office Hours 50 🔥 Play https://youtube.com/watch?v=NF8NIC7aB6Q - Cluster, Workflows & Cloudflare Durable Objects Play https://youtube.com/watch?v=CBPttaqp9Ec - Effect Cluster, Part 3 | Module of the Week 5 Play https://youtube.com/watch?v=MQnQ87Nv0gU The Effect Merch Store https://effect.website/merch offers a selection of Effect-branded items designed for the community. All orders are processed and fully managed through Printful https://www.printful.com/ . Effect Merch is here We’re excited to announce the launch of our Effect merch page Grab your favorite swag & show your love for Effect in style 🧢 effect.website/merch https://effect.website/merch That’s all for this week. Thank you for being a vital part of our community. Your feedback is highly valued as we fine-tune this format. Feel free to share your thoughts, and we’ll do our best to tailor it to the needs of our community. Effect Community Team Previous Module of the Week - Cluster, Part 3 https://effect.website/blog/module-of-the-week/cluster-delivery