Merge upstream/main into series/3.x-avs

Sync fork with upstream monix/monix:main. Brings in VarHandle atomics,
Scala 3.8.2, updated dependencies, scalafmt formatting, and mima
refactoring. Conflicts resolved preferring upstream style.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: halotukozak

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "github-actions"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/workflows/build.yml

@@ -2,22 +2,22 @@ name: build
 
 on:
   pull_request:
-    branches: [ 'series/*' ]
+    branches: ['series/*', 'main']
   push:
-    branches: [ 'series/*' ]
-    tags: [ "v[0-9]+*" ]
+    branches: ['series/*', 'main']
+    tags: ["v[0-9]+*"]
 
 jobs:
   jvm-tests:
     name: JVM / scala ${{ matrix.scala }}, jdk ${{ matrix.java }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
-        java: [ 11, 17, 21, 25 ]
+        java: [ 17, 21, 25 ]
         # WARN: build.sbt depends on this key path, as scalaVersion and
         # crossScalaVersions is determined from it
-        scala: [ 2.13.18, 3.3.7 ]
+        scala: [ 2.13.18, 3.8.2 ]
 
     env:
       CI: true
@@ -26,8 +26,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4
         with:
+          java-version: "${{ matrix.java }}"
           distribution: temurin
-          java-version: ${{ matrix.java }}
       - uses: sbt/setup-sbt@v1
 
       - name: Cache ivy2
@@ -56,17 +56,24 @@ jobs:
           PLATFORM: ${{ matrix.java }}
           SBT_COMMAND: ci-jvm
 
+      - name: sbt reactiveTests/test
+        run: ./.github/scripts/exec-sbt-command
+        env:
+          SCALA_VERSION: ${{ matrix.scala }}
+          PLATFORM: ${{ matrix.java }}
+          SBT_COMMAND: "reactiveTests/test"
+
   js-tests:
     name: JS / scala ${{ matrix.scala }}, jdk ${{ matrix.java }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
       matrix:
         # WARN: build.sbt depends on this key path, as scalaVersion and
         # crossScalaVersions is determined from it
         include:
-          - { java: 11, scala: 2.13.18 }
-          - { java: 11, scala: 3.3.7 }
+          - { java: 17, scala: 2.13.18 }
+          - { java: 17, scala: 3.8.2 }
 
     env:
       CI: true
@@ -75,8 +82,8 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4
         with:
+          java-version: "${{ matrix.java }}"
           distribution: temurin
-          java-version: ${{ matrix.java }}
       - uses: sbt/setup-sbt@v1
 
       - name: Cache ivy2
@@ -101,7 +108,7 @@ jobs:
       - name: Setup NodeJS
         uses: actions/setup-node@v4
         with:
-          node-version: 14
+          node-version: 20
 
       - name: sbt ci-js
         run: |
@@ -113,20 +120,24 @@ jobs:
 
   mima:
     name: Mima / scala ${{ matrix.scala }}, jdk ${{ matrix.java }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
+
+    env:
+      CI: true
+
     strategy:
       fail-fast: false
       matrix:
         include:
-          - { java: 11, scala: 2.13.18 }
-          - { java: 11, scala: 3.3.7 }
+          - { java: 17, scala: 2.13.18 }
+          - { java: 17, scala: 3.8.2 }
 
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4
         with:
+          java-version: "${{ matrix.java }}"
           distribution: temurin
-          java-version: ${{ matrix.java }}
       - uses: sbt/setup-sbt@v1
 
       - name: Cache ivy2
@@ -155,23 +166,74 @@ jobs:
           SCALA_VERSION: ${{ matrix.scala }}
           SBT_COMMAND: mimaReportBinaryIssues
 
+  scalafmt:
+    name: Scalafmt / scala ${{ matrix.scala }}, jdk ${{ matrix.java }}
+    runs-on: ubuntu-22.04
+
+    env:
+      CI: true
+
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - { java: 17, scala: 2.13.18 }
+          - { java: 17, scala: 3.8.2 }
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-java@v4
+        with:
+          java-version: "${{ matrix.java }}"
+          distribution: temurin
+      - uses: sbt/setup-sbt@v1
+
+      - name: Cache ivy2
+        uses: actions/cache@v4
+        with:
+          path: ~/.ivy2/cache
+          key: ${{ runner.os }}-sbt-ivy-cache-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
+
+      - name: Cache coursier (linux)
+        if: contains(runner.os, 'linux')
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/coursier/v1
+          key: ${{ runner.os }}-sbt-coursier-cache-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
+
+      - name: Cache sbt
+        uses: actions/cache@v4
+        with:
+          path: ~/.sbt
+          key: ${{ runner.os }}-sbt-cache-${{ hashFiles('**/*.sbt') }}-${{ hashFiles('project/build.properties') }}
+
+      - name: sbt scalafmtCheckAll
+        run: |
+          ./.github/scripts/exec-sbt-command
+        env:
+          SCALA_VERSION: ${{ matrix.scala }}
+          SBT_COMMAND: "scalafmtCheckAll scalafmtSbtCheck"
+
   unidoc:
     name: Unidoc / scala ${{ matrix.scala }}, jdk ${{ matrix.java }}
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-22.04
+
+    env:
+      CI: true
+
     strategy:
       fail-fast: false
       matrix:
         include:
-          - { java: 11, scala: 2.13.18 }
-          # TODO: enable this after it works!
-          # - { java: 11, scala: 3.3.5 }
+          - { java: 17, scala: 2.13.18 }
+          - { java: 17, scala: 3.8.2 }
 
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4
         with:
+          java-version: "${{ matrix.java }}"
           distribution: temurin
-          java-version: ${{ matrix.java }}
       - uses: sbt/setup-sbt@v1
 
       - name: Cache ivy2
@@ -202,28 +264,33 @@ jobs:
 
   all_tests:
     name: All Tests
-    needs: [ jvm-tests, js-tests, mima, unidoc ]
-    runs-on: ubuntu-latest
+    if: always()
+    needs: [ jvm-tests, js-tests, mima, scalafmt, unidoc ]
+    runs-on: ubuntu-22.04
     steps:
-      - name: Ack
-        run: |
-          echo "All done."
+    - name: Validate required tests
+      uses: re-actors/alls-green@release/v1
+      with:
+        jobs: ${{ toJSON(needs) }}
 
   publish:
     name: Publish to Sonatype
-    if: github.event_name == 'push' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/series/3.x')
+    if: github.event_name == 'push' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/series/3.x-avs')
     needs: [ all_tests ]
 
-    runs-on: ubuntu-latest
+    env:
+      CI: true
+
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 100
 
       - uses: actions/setup-java@v4
         with:
+          java-version: 17
           distribution: temurin
-          java-version: 11
       - uses: sbt/setup-sbt@v1
 
       - name: Install GnuPG2

.github/workflows/manual-publish.yml

@@ -6,7 +6,7 @@ on:
       ref_to_publish:
         description: 'Ref (branch or tag)'
         required: true
-        default: 'refs/heads/series/3.x'
+        default: 'refs/heads/main'
       stable_version:
         description: 'Stable version? (true=staging, false=snapshot)'
         required: true
@@ -16,7 +16,10 @@ jobs:
   publish:
     name: Publish to Sonatype (Request)
 
-    runs-on: ubuntu-latest
+    env:
+      CI: true
+
+    runs-on: ubuntu-22.04
     steps:
       - uses: actions/checkout@v4
         with:
@@ -25,8 +28,8 @@ jobs:
 
       - uses: actions/setup-java@v4
         with:
+          java-version: 17
           distribution: temurin
-          java-version: 11
       - uses: sbt/setup-sbt@v1
 
       - name: Install GnuPG2

.gitignore

@@ -15,7 +15,9 @@ TAGS
 .tags
 .metals
 .bloop
+.bsp
 metals.sbt
 .vscode
 .bsp
-.planning/
+*.sublime*
+.sisyphus/

.scala-steward.conf

@@ -1,6 +1,6 @@
 pullRequests.frequency = "7 days"
 
-updates.pin  = [ 
-  { groupId = "org.typelevel", artifactId="cats-effect", version = "2." },
-  { groupId = "org.typelevel", artifactId="cats-effect-laws", version = "2." },
-]
+#updates.pin  = [ 
+#  { groupId = "org.typelevel", artifactId="cats-effect", version = "2." },
+#  { groupId = "org.typelevel", artifactId="cats-effect-laws", version = "2." },
+#]

.scalafmt.conf

@@ -10,7 +10,7 @@ align.tokens = [
 ]
 
 fileOverride {
-  "glob:**/src/main/scala_3.0/**" {
+  "glob:**/src/main/scala-3*/**" {
     runner.dialect = scala3
   },
   "glob:**/*.sbt" {

AGENTS.md

@@ -0,0 +1,15 @@
+# Agent Instructions for Monix
+
+This file contains mandatory rules for AI agents (Copilot, Claude, Cursor, etc.) working on this repository.
+**Any violation is a CI-breaking mistake!**
+
+---
+
+## Code rules
+
+- Never workaround the compiler, make an effort to solve errors in an idiomatic way:
+  - Avoid `asInstanceOf` downcasting, unless there's no other way (e.g., untagged union types in Scala 3).
+  - `@nowarn` annotations, or other ways for supressing warnings/errors, are not permitted without the user's consent.
+    - We fix warnings, we don't ignore them.
+- Use package imports, instead of fully qualified names.
+- Make an effort to write idiomatic, yet performant Scala code.

CHANGES.md

@@ -1,3 +1,19 @@
+## Version 3.5.0 (Mar 31, 2026)
+
+This release updates Monix 3.x support baselines for modern JVM and Scala toolchains.
+
+Breaking changes:
+
+- JDK `17` is now the minimum supported runtime and build target.
+- JDK `21` is now part of the validated support matrix.
+- Scala `2.12` support is dropped.
+- Scala `3` is upgraded to `3.8.2`.
+- Legacy `sun.misc.Unsafe`-based internals were removed in favor of JDK `VarHandle`-based implementations.
+
+This release was made possible by the work and feedback of:
+
+- Alexandru Nedelcu (@alexandru)
+
 ## Version 3.4.1 (May 7, 2022)
 
 This is a minor bug-fixing release for the 3.x series.
@@ -1531,7 +1547,7 @@ Bug fixes:
 Build:
 
 - enabled the Scala
-  [Migration Manager](https://github.com/typesafehub/migration-manager)
+  [Migration Manager](https://github.com/lightbend/mima)
   (MiMa) in `build.sbt` to check for backwards compatibility problems
 - [Issue #322](https://github.com/monix/monix/issues/322):
   Switch projects which use `CrossVersion.full/"org.scala-lang"`

CONTRIBUTING.md

@@ -2,7 +2,7 @@
 
 The Monix project welcomes contributions from anybody wishing to participate.
 All code or documentation that is provided must be licensed with Apache 2.0
-(see LICENSE.txt).
+(see `LICENSE.txt`).
 
 ## Code of Conduct