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Cross-platform observation delivery + WebAssembly build support #152

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3 changes: 3 additions & 0 deletions Package.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,9 @@ let package = Package(
)
],
dependencies: [
// Bump to the Cache release that includes the WebAssembly + Linux collection-cast fixes
// (0xLeif/Cache#30) once it is tagged — that is what makes wasm builds and Linux
// collection-typed state fully correct end-to-end.
.package(url: "https://github.com/0xLeif/Cache", from: "2.0.0"),
.package(url: "https://github.com/apple/swift-docc-plugin", from: "1.4.0")
],
Expand Down
4 changes: 2 additions & 2 deletions Sources/AppState/Application/Application+public.swift
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import Foundation
#if !os(Linux) && !os(Windows)
#if canImport(SwiftUI)
import SwiftUI
#endif

Expand Down Expand Up @@ -387,7 +387,7 @@ public extension Application {
}
}

#if !os(Linux) && !os(Windows)
#if canImport(SwiftUI)
// MARK: - SwiftUI Preview Dependency Functions

public extension Application {
Expand Down
16 changes: 7 additions & 9 deletions Sources/AppState/Application/Application.swift
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Original file line number Diff line number Diff line change
@@ -1,7 +1,9 @@
import Cache
import Observation
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
#endif
#if canImport(OSLog)
import OSLog
#else
import Foundation
Expand All @@ -14,7 +16,7 @@ open class Application: NSObject {
@MainActor
static var shared: Application = Application()

#if !os(Linux) && !os(Windows)
#if canImport(OSLog)
/// Logger specifically for AppState
public var logger: Dependency<Logger> {
dependency(Logger(subsystem: "AppState", category: "Application"))
Expand Down Expand Up @@ -51,7 +53,7 @@ open class Application: NSObject {
/// the synthesized `@Observable` registrar, which is `Sendable` and internally synchronized.
private var changeAnchor: Int = 0

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A set to store cancellables for Combine subscriptions, ensuring they are properly managed and released.
@ObservationIgnored
private var bag: Set<AnyCancellable> = Set()
Expand All @@ -77,10 +79,6 @@ open class Application: NSObject {

setup(self)
loadDefaultDependencies()

#if !os(Linux) && !os(Windows)
consume(object: cache)
#endif
}

/// Registers the current Observation tracking scope (such as a SwiftUI view body) as dependent on
Expand Down Expand Up @@ -112,7 +110,7 @@ open class Application: NSObject {
changeAnchor &+= 1
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/**
Called when the value of one or more keys in the local key-value store changed due to incoming data pushed from iCloud.

Expand Down Expand Up @@ -152,7 +150,7 @@ open class Application: NSObject {
load(dependency: \.fileManager)
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// Consumes changes in the provided ObservableObject and sends updates before the object will change.
///
/// - Parameter object: The ObservableObject to observe
Expand Down
2 changes: 0 additions & 2 deletions Sources/AppState/Application/Types/Dependency/Slice/Application+DependencySlice.swift
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Expand Up @@ -34,9 +34,7 @@ extension Application.DependencySlice where SliceKeyPath == WritableKeyPath<Valu
public var value: SliceValue {
get { dependency.value[keyPath: keyPath] }
set {
#if !os(Linux) && !os(Windows)
Application.shared.notifyChange()

@gemini-code-assist gemini-code-assist Bot Jun 11, 2026

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high

Since Application.DependencySlice is not restricted to @MainActor, its setter can be invoked from background threads (e.g., when a background service updates its state). Calling Application.shared.notifyChange() directly on a background thread will trigger the assertion assert(Thread.isMainThread) inside notifyChange() and crash the application.

To prevent this, we should ensure notifyChange() is always dispatched to the main thread.

Alternative: A cleaner approach would be to make Application.notifyChange() itself thread-safe by internally checking Thread.isMainThread and dispatching to DispatchQueue.main if necessary, which would eliminate the need for these checks at every call site.

            if Thread.isMainThread {
                Application.shared.notifyChange()
            } else {
                DispatchQueue.main.async {
                    Application.shared.notifyChange()
                }
            }

#endif
dependency.value[keyPath: keyPath] = newValue
}
}
Expand Down
2 changes: 1 addition & 1 deletion Sources/AppState/Application/Types/Helper/Application+ApplicationPreview.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#if !os(Linux) && !os(Windows)
#if canImport(SwiftUI)
import SwiftUI

extension Application {
Expand Down
4 changes: 3 additions & 1 deletion Sources/AppState/Application/Types/State/Application+FileState.swift
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Expand Up @@ -74,7 +74,7 @@ extension Application {
)
}

#if (!os(Linux) && !os(Windows))
#if canImport(ObjectiveC)
if NSClassFromString("XCTest") == nil {
Task {
await MainActor.run {
Expand Down Expand Up @@ -149,6 +149,8 @@ extension Application {
)
}
}

shared.notifyChange()

@gemini-code-assist gemini-code-assist Bot Jun 11, 2026

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high

Since FileState.value is not restricted to @MainActor, its setter can be invoked from background threads. Calling shared.notifyChange() directly on a background thread will trigger the assertion assert(Thread.isMainThread) inside notifyChange() and crash the application.

To prevent this, we should ensure notifyChange() is always dispatched to the main thread.

Alternative: A cleaner approach would be to make Application.notifyChange() itself thread-safe by internally checking Thread.isMainThread and dispatching to DispatchQueue.main if necessary, which would eliminate the need for these checks at every call site.

                if Thread.isMainThread {
                    shared.notifyChange()
                } else {
                    DispatchQueue.main.async {
                        shared.notifyChange()
                    }
                }

}
}

Expand Down
20 changes: 18 additions & 2 deletions Sources/AppState/Application/Types/State/Application+State.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ extension Application {
}

public static var emoji: Character {
#if !os(Linux) && !os(Windows)
#if canImport(OSLog)
return "🔄"
#else
return "📦"
Expand All @@ -27,6 +27,21 @@ extension Application {
private let initial: Value

/// The current state value.
///
/// - Note: **Issue #151 — Linux `_arrayForceCast` crash.**
/// The `shared.cache.get(scope.key, as: State<Value>.self)` call below performs
/// an `Any → State<Value>` dynamic cast inside `Dictionary+Cacheable.swift:18`
/// (`self[key] as? Item`). On Linux, when `Value` is a collection type such as
/// `[Element]`, the Swift runtime's `swift_dynamicCast` path invokes
/// `_arrayForceCast` for the generic parameter, which crashes with a
/// `swift_dynamicCastFailure`. This is a known Swift-on-Linux stdlib/runtime
/// limitation (SR-4049 / swift#40956) affecting `as?` casts from `Any` to
/// generic structs whose generic parameters are array types. A clean fix requires
/// either: (a) replacing `Cache<String, Any>` with a type-index keyed store so
/// `Any` is never the concrete container value type, or (b) filing a Cache library
/// issue to store a type-erased wrapper that avoids the metatype dereference during
/// cast. Until then, `State<[T]>` and `FileState<[T]?>` will crash on Linux when
/// their value is read after being evicted from the in-memory cache.
@MainActor
public var value: Value {
get {
Expand All @@ -47,7 +62,7 @@ extension Application {
forKey: scope.key
)
}
#if (!os(Linux) && !os(Windows))
#if canImport(ObjectiveC)
if NSClassFromString("XCTest") == nil {
Task { @MainActor in
setValue()
Expand All @@ -73,6 +88,7 @@ extension Application {
),
forKey: scope.key
)
shared.notifyChange()
}
}

Expand Down
2 changes: 2 additions & 0 deletions Sources/AppState/Application/Types/State/Application+StoredState.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,8 @@ extension Application {
userDefaults.set(newValue, forKey: scope.key)
}
}

shared.notifyChange()

@gemini-code-assist gemini-code-assist Bot Jun 11, 2026

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high

Since StoredState.value is not restricted to @MainActor, its setter can be invoked from background threads. Calling shared.notifyChange() directly on a background thread will trigger the assertion assert(Thread.isMainThread) inside notifyChange() and crash the application.

To prevent this, we should ensure notifyChange() is always dispatched to the main thread.

Alternative: A cleaner approach would be to make Application.notifyChange() itself thread-safe by internally checking Thread.isMainThread and dispatching to DispatchQueue.main if necessary, which would eliminate the need for these checks at every call site.

                if Thread.isMainThread {
                    shared.notifyChange()
                } else {
                    DispatchQueue.main.async {
                        shared.notifyChange()
                    }
                }

}
}

Expand Down
2 changes: 2 additions & 0 deletions Sources/AppState/Application/Types/State/Application+SyncState.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -105,6 +105,8 @@ extension Application {
)
}
}

shared.notifyChange()

@gemini-code-assist gemini-code-assist Bot Jun 11, 2026

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high

Since SyncState.value is not restricted to @MainActor, its setter can be invoked from background threads. Calling shared.notifyChange() directly on a background thread will trigger the assertion assert(Thread.isMainThread) inside notifyChange() and crash the application.

To prevent this, we should ensure notifyChange() is always dispatched to the main thread.

Alternative: A cleaner approach would be to make Application.notifyChange() itself thread-safe by internally checking Thread.isMainThread and dispatching to DispatchQueue.main if necessary, which would eliminate the need for these checks at every call site.

                if Thread.isMainThread {
                    shared.notifyChange()
                } else {
                    DispatchQueue.main.async {
                        shared.notifyChange()
                    }
                }

}
}

Expand Down
8 changes: 3 additions & 5 deletions Sources/AppState/PropertyWrappers/Dependency/Slice/DependencySlice.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import SwiftUI
#endif

Expand Down Expand Up @@ -45,14 +45,12 @@ import SwiftUI
)

var dependency = app.value(keyPath: dependencyKeyPath)
#if !os(Linux) && !os(Windows)
Application.shared.notifyChange()
#endif
dependency.value[keyPath: valueKeyPath] = newValue
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `Dependency`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<SliceValue> {
Expand Down Expand Up @@ -96,6 +94,6 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension DependencySlice: DynamicProperty { }
#endif
8 changes: 4 additions & 4 deletions Sources/AppState/PropertyWrappers/State/AppState.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
import SwiftUI
#endif
Expand Down Expand Up @@ -45,7 +45,7 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `State`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<Value> {
Expand Down Expand Up @@ -76,7 +76,7 @@ import SwiftUI
self.column = column
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A property wrapper's synthetic storage property. This is just for SwiftUI to mutate the `wrappedValue` and send event through `objectWillChange` publisher when the `wrappedValue` changes
@MainActor
public static subscript<OuterSelf: ObservableObject>(
Expand All @@ -99,6 +99,6 @@ import SwiftUI
#endif
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension AppState: DynamicProperty { }
#endif
8 changes: 4 additions & 4 deletions Sources/AppState/PropertyWrappers/State/FileState.swift
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import Foundation
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
import SwiftUI
#endif
Expand Down Expand Up @@ -46,7 +46,7 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `State`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<Value> {
Expand Down Expand Up @@ -77,7 +77,7 @@ import SwiftUI
self.column = column
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A property wrapper's synthetic storage property. This is just for SwiftUI to mutate the `wrappedValue` and send event through `objectWillChange` publisher when the `wrappedValue` changes
@MainActor
public static subscript<OuterSelf: ObservableObject>(
Expand All @@ -100,6 +100,6 @@ import SwiftUI
#endif
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension FileState: DynamicProperty { }
#endif
8 changes: 4 additions & 4 deletions Sources/AppState/PropertyWrappers/State/Slice/OptionalSlice.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
import SwiftUI
#endif
Expand Down Expand Up @@ -89,7 +89,7 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `State`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<SliceValue?> {
Expand Down Expand Up @@ -166,7 +166,7 @@ import SwiftUI
self.sliceKeyPath = "\(stateKeyPathString)\(valueKeyPathString)"
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A property wrapper's synthetic storage property. This is just for SwiftUI to mutate the `wrappedValue` and send event through `objectWillChange` publisher when the `wrappedValue` changes
@MainActor
public static subscript<OuterSelf: ObservableObject>(
Expand All @@ -189,6 +189,6 @@ import SwiftUI
#endif
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension OptionalSlice: DynamicProperty { }
#endif
8 changes: 4 additions & 4 deletions Sources/AppState/PropertyWrappers/State/Slice/Slice.swift
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
import SwiftUI
#endif
Expand Down Expand Up @@ -50,7 +50,7 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `State`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<SliceValue> {
Expand Down Expand Up @@ -93,7 +93,7 @@ import SwiftUI
self.sliceKeyPath = "\(stateKeyPathString)\(valueKeyPathString)"
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A property wrapper's synthetic storage property. This is just for SwiftUI to mutate the `wrappedValue` and send event through `objectWillChange` publisher when the `wrappedValue` changes
@MainActor
public static subscript<OuterSelf: ObservableObject>(
Expand All @@ -116,6 +116,6 @@ import SwiftUI
#endif
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension Slice: DynamicProperty { }
#endif
8 changes: 4 additions & 4 deletions Sources/AppState/PropertyWrappers/State/StoredState.swift
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import Foundation
#if !os(Linux) && !os(Windows)
#if canImport(Combine)
import Combine
import SwiftUI
#endif
Expand Down Expand Up @@ -46,7 +46,7 @@ import SwiftUI
}
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A binding to the `State`'s value, which can be used with SwiftUI views.
@MainActor
public var projectedValue: Binding<Value> {
Expand Down Expand Up @@ -77,7 +77,7 @@ import SwiftUI
self.column = column
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
/// A property wrapper's synthetic storage property. This is just for SwiftUI to mutate the `wrappedValue` and send event through `objectWillChange` publisher when the `wrappedValue` changes
@MainActor
public static subscript<OuterSelf: ObservableObject>(
Expand All @@ -100,6 +100,6 @@ import SwiftUI
#endif
}

#if !os(Linux) && !os(Windows)
#if canImport(Combine)
extension StoredState: DynamicProperty { }
#endif
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