Feat/init repo

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  format:
+    name: Swift Format
+    runs-on: macos-26
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check Formatting
+        run: swift format lint --strict --parallel --recursive Sources Tests
+
+  build-and-test:
+    name: ${{ matrix.name }}
+    runs-on: macos-26
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: "iOS"
+            destination: "platform=iOS Simulator,name=iPhone 17 Pro Max,OS=26.2"
+          - name: "macOS"
+            destination: "platform=macOS"
+          - name: "Mac Catalyst"
+            destination: "platform=macOS,variant=Mac Catalyst"
+          - name: "tvOS"
+            destination: "platform=tvOS Simulator,name=Apple TV,OS=26.2"
+          - name: "visionOS"
+            destination: "platform=visionOS Simulator,name=Apple Vision Pro,OS=26.2"
+          - name: "watchOS"
+            destination: "platform=watchOS Simulator,name=Apple Watch Series 11 (46mm),OS=26.2"
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build & Test
+        run: |
+          xcodebuild ${{ matrix.action }} -scheme ObservationKit-Package -destination '${{ matrix.destination }}'

.github/workflows/release.yml

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+name: release
+
+on:
+  workflow_dispatch:
+    inputs:
+      bump_version_scheme:
+        type: choice
+        description: "Bump version scheme"
+        required: true
+        default: "patch"
+        options:
+          - "patch"
+          - "minor"
+          - "major"
+
+jobs:
+  release-on-push:
+    runs-on: ubuntu-latest
+    env:
+      GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+    steps:
+      - uses: rymndhng/release-on-push-action@master
+        with:
+          bump_version_scheme: ${{ github.event_name == 'push' && github.ref == 'refs/heads/main' && 'patch' || inputs.bump_version_scheme }}

.gitignore

@@ -0,0 +1,9 @@
+.DS_Store
+/.build
+/Packages
+xcuserdata/
+DerivedData/
+.swiftpm/configuration/registries.json
+.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata
+.netrc
+*.log

.swift-format

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+{
+  "fileScopedDeclarationPrivacy" : {
+    "accessLevel" : "private"
+  },
+  "indentConditionalCompilationBlocks" : true,
+  "indentSwitchCaseLabels" : false,
+  "indentation" : {
+    "spaces" : 2
+  },
+  "lineBreakAroundMultilineExpressionChainComponents" : false,
+  "lineBreakBeforeControlFlowKeywords" : false,
+  "lineBreakBeforeEachArgument" : false,
+  "lineBreakBeforeEachGenericRequirement" : false,
+  "lineBreakBetweenDeclarationAttributes" : false,
+  "lineLength" : 100,
+  "maximumBlankLines" : 1,
+  "multiElementCollectionTrailingCommas" : true,
+  "noAssignmentInExpressions" : {
+    "allowedFunctions" : [
+      "XCTAssertNoThrow"
+    ]
+  },
+  "prioritizeKeepingFunctionOutputTogether" : false,
+  "reflowMultilineStringLiterals" : "never",
+  "respectsExistingLineBreaks" : true,
+  "rules" : {
+    "AllPublicDeclarationsHaveDocumentation" : false,
+    "AlwaysUseLiteralForEmptyCollectionInit" : false,
+    "AlwaysUseLowerCamelCase" : true,
+    "AmbiguousTrailingClosureOverload" : true,
+    "AvoidRetroactiveConformances" : true,
+    "BeginDocumentationCommentWithOneLineSummary" : false,
+    "DoNotUseSemicolons" : true,
+    "DontRepeatTypeInStaticProperties" : true,
+    "FileScopedDeclarationPrivacy" : true,
+    "FullyIndirectEnum" : true,
+    "GroupNumericLiterals" : true,
+    "IdentifiersMustBeASCII" : true,
+    "NeverForceUnwrap" : false,
+    "NeverUseForceTry" : false,
+    "NeverUseImplicitlyUnwrappedOptionals" : false,
+    "NoAccessLevelOnExtensionDeclaration" : true,
+    "NoAssignmentInExpressions" : true,
+    "NoBlockComments" : true,
+    "NoCasesWithOnlyFallthrough" : true,
+    "NoEmptyLinesOpeningClosingBraces" : false,
+    "NoEmptyTrailingClosureParentheses" : true,
+    "NoLabelsInCasePatterns" : true,
+    "NoLeadingUnderscores" : false,
+    "NoParensAroundConditions" : true,
+    "NoPlaygroundLiterals" : true,
+    "NoVoidReturnOnFunctionSignature" : true,
+    "OmitExplicitReturns" : false,
+    "OneCasePerLine" : true,
+    "OneVariableDeclarationPerLine" : true,
+    "OnlyOneTrailingClosureArgument" : true,
+    "OrderedImports" : true,
+    "ReplaceForEachWithForLoop" : true,
+    "ReturnVoidInsteadOfEmptyTuple" : true,
+    "TypeNamesShouldBeCapitalized" : true,
+    "UseEarlyExits" : false,
+    "UseExplicitNilCheckInConditions" : true,
+    "UseLetInEveryBoundCaseVariable" : true,
+    "UseShorthandTypeNames" : true,
+    "UseSingleLinePropertyGetter" : true,
+    "UseSynthesizedInitializer" : true,
+    "UseTripleSlashForDocumentationComments" : true,
+    "UseWhereClausesInForLoops" : false,
+    "ValidateDocumentationComments" : false
+  },
+  "spacesAroundRangeFormationOperators" : false,
+  "spacesBeforeEndOfLineComments" : 2,
+  "tabWidth" : 8,
+  "version" : 1
+}

.swiftpm/xcode/package.xcworkspace/xcshareddata/IDETemplateMacros.plist

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>FILEHEADER</key>
+	<string>
+//
+//  ___FILENAME___
+//  ___TARGET___
+//
+//  Copyright (c) ___YEAR___ Jacob Fielding
+//</string>
+</dict>
+</plist>

LICENSE

@@ -26,3 +26,13 @@ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+---
+
+Portions of this project are derived from the Swift.org open source project
+(https://github.com/swiftlang/swift), which is licensed under the
+Apache License, Version 2.0, with Runtime Library Exception.
+
+The full text of the Apache License 2.0 is included in LICENSE-APACHE.
+See https://github.com/swiftlang/swift/blob/main/LICENSE.txt for the original license including the
+Runtime Library Exception.

Package.swift

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+// swift-tools-version: 6.2
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "ObservationKit",
+    platforms: [
+        .iOS(.v17),
+        .macCatalyst(.v17),
+        .macOS(.v14),
+        .tvOS(.v17),
+        .visionOS(.v1),
+        .watchOS(.v10)
+    ],
+    products: [
+        .library(
+            name: "ObservationTesting",
+            targets: ["ObservationTesting"]
+        ),
+        .library(
+            name: "ObservationShim",
+            targets: ["ObservationShim"]
+        ),
+    ],
+    dependencies: [
+        .package(url: "https://github.com/apple/swift-async-algorithms.git", .upToNextMajor(from: "1.1.2")),
+        .package(url: "https://github.com/pointfreeco/swift-concurrency-extras.git", .upToNextMajor(from: "1.3.2")),
+
+        // Testing
+        // TODO: Make this conditional
+        .package(url: "https://github.com/apple/swift-numerics.git", .upToNextMajor(from: "1.1.1"))
+    ],
+    targets: [
+        .target(
+            name: "ObservationTesting",
+            dependencies: [
+                .product(name: "AsyncAlgorithms", package: "swift-async-algorithms"),
+                .product(name: "ConcurrencyExtras", package: "swift-concurrency-extras")
+            ]
+        ),
+        .target(
+            name: "ObservationShim"
+        ),
+
+        // MARK: Testing
+
+        .testTarget(
+            name: "ObservationTestingTests",
+            dependencies: [
+                "ObservationTesting",
+                .product(name: "Numerics", package: "swift-numerics")
+            ]
+        ),
+        .testTarget(
+            name: "ObservationShimTests",
+            dependencies: [
+                "ObservationShim",
+                "ObservationTesting"
+            ]
+        ),
+    ],
+    swiftLanguageModes: [.v6]
+)

README.md

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+# ObservationKit
+
+A small library that aims to make it possible for me to adopt the Observation framework now, instead of years in the future.
+
+## ObservationShim
+
+This is a copy of SwiftLang's [`Observations.swift`](https://github.com/phausler/ObservationSequence/blob/main/Sources/ObservationSequence/Observations.swift)
+with some small tweaks to enable iOS 17+ compatibility. There are endless online discussions and dozens of projects that aim to enable the use of `AsyncSequence` 
+and modern concurrency based streaming tools in favor of `Combine`. This one clicked thanks to this Swift Forums post 
+[iOS 18 support for the Observations struct is being dropped before release?](https://forums.swift.org/t/ios-18-support-for-the-observations-struct-is-being-dropped-before-release/81942/5).
+
+> [!IMPORTANT]  
+> This is not aimed at replacing `Observations`. It's simply a shim you can use to start making real 
+> use of the Apple Observations framework in favor of a bunch of bridges to other data sources like `Combine`
+
+This example shows how you'd effectively erase the official and shimmed backport into an
+`AsyncStream` to use outside of SwiftUI. Note Pointfree Co's [`ConcurrencyExtras`](https://github.com/pointfreeco/swift-concurrency-extras) 
+was used to allow erasure into a clean `AsyncStream<Element>`.
+
+```swift
+func observableStream(
+    _ emit: @escaping @isolated(any) @Sendable () -> Element
+) -> AsyncStream<Element> {
+    if #available(iOS 26.0, *) {
+        let official = Observations(emit)
+        return AsyncStream(official)
+    } else {
+        let backport = ObservationsShim(emit)
+        return AsyncStream(backport)
+    }
+}
+```
+
+### References
+
+- @vanvoorden [iOS 18 support for the Observations struct is being dropped before release?](https://forums.swift.org/t/ios-18-support-for-the-observations-struct-is-being-dropped-before-release/81942/5)
+- @phausler [iOS 18 support for the Observations struct is being dropped before release?](https://forums.swift.org/t/ios-18-support-for-the-observations-struct-is-being-dropped-before-release/81942/6)
+- [`Observations.swift`](https://github.com/phausler/ObservationSequence/blob/main/Sources/ObservationSequence/Observations.swift)
+
+## ObservationTesting
+
+Swift Testing introduced a new paradigm for async confirmation in [Testing asyncronous code](https://developer.apple.com/documentation/testing/testing-asynchronous-code). 
+The swift tools are totally acceptable, but can be quite verbose and a bit tricky, especially testing outputs from `AsyncSequences`. 
+The `ObservationTesting` library enables concise unit tests for `AsyncSequences`. This also works really well with `Observations` and `ObservationsShim`.
+
+This includes verifying `Equatable` elements over time.
+
+```swift
+@Test("A value is emitted from the stream")
+func basic() async throws {
+    let stream = AsyncStream { continuation in
+        continuation.yield("cats")
+        continuation.yield("dogs")
+        continuation.yield("lizards")
+    }
+
+    try await stream.fulfillment(of: "cats", "dogs", "lizards")
+}
+```
+
+Or complex conditions that can't easily be represented as expected value(s).
+
+```swift
+@Test("A condition is verified on the stream")
+func conditionMet() async throws {
+    let stream = AsyncStream { continuation in
+        continuation.yield("cats")
+    }
+
+    try await stream.fulfillment { value in
+        value == "cats"
+    }
+}
+```

Sources/ObservationShim/ManagedCriticalState.swift

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+//
+//  ManagedCriticalState.swift
+//  ObservationShim
+//
+//  Copyright (c) 2026 Jacob Fielding
+//
+
+import Foundation
+
+final class _ManagedCriticalState<State: Sendable>: @unchecked Sendable {
+  private let lock = NSRecursiveLock()
+  private var state: State
+
+  init(_ initial: State) {
+    state = initial
+  }
+
+  func withCriticalRegion<R>(
+    _ critical: (inout State) throws -> R
+  ) rethrows -> R {
+    try lock.withLock {
+      try critical(&state)
+    }
+  }
+}