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mobilecritical PriorityID: kmp-structured-concurrency-lifetime-boundary

Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary

Mandates strict lifecycle-bound CoroutineScope termination and bidirectional cancellation propagation across Android ViewModels and Swift/Objective-C interop runtimes. Prohibits detached jobs, unbound GlobalScope invocations, and manual un-bridged async calls to eliminate native heap leaks, uncollected Kotlin/Native reference graphs, and zombie network dispatches.

Prohibited Anti-Pattern: Unbound Coroutine Bridging Yielding Zombie Tasks and Swift/Native Memory Leaks

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---
description: Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary - Mandates strict lifecycle-bound CoroutineScope termination and bidirectional cancellation propagation across Android ViewModels and Swift/Objective-C interop runtimes. Prohibits detached jobs, unbound GlobalScope invocations, and manual un-bridged async calls to eliminate native heap leaks, uncollected Kotlin/Native reference graphs, and zombie network dispatches.
globs: **/shared/src/**/*.{kt,kts}, **/iosApp/**/*.swift, **/androidApp/**/*.kt, **/commonMain/**/*.kt, **/iosMain/**/*.kt
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/kmp-structured-concurrency-lifetime-boundary"
---

# Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary

> **Severity**: CRITICAL | **Category**: mobile
> **Anti-Pattern Warning**: Unbound Coroutine Bridging Yielding Zombie Tasks and Swift/Native Memory Leaks

## System Constraints
You are a Principal Mobile Architect enforcing Kotlin Multiplatform 2.1 Structured Concurrency Lifetime Boundaries. Mandate that all cross-platform coroutines launched from or exposed to native platforms (iOS Swift and Android Jetpack) are bound to explicit cancellation scopes. Prohibit unbound GlobalScope and unmanaged native Swift async execution paths without task cancellation bridging.

## Strict Guidelines
- Engineers MUST ALWAYS bind shared Kotlin Multiplatform CoroutineScope instances to platform lifecycle abstractions (Android ViewModel `viewModelScope` and iOS `deinit` / SwiftUI `.task` hooks).
- Engineers MUST NOT expose unbounded suspending functions or unmanaged `GlobalScope` dispatches to Swift; wrap scopes in explicit cancellation boundaries (e.g., `Closeable` or `Job.cancel()` handles).
- Code MUST bridge Swift structured concurrency cancellation directly to Kotlin coroutine `Job.cancel()` using `withTaskCancellationHandler` or SKIE/KMP-native lifecycle wrappers.
- Services MUST ensure that all streaming flows exposed across the Kotlin/Native boundary cancel upstream producers when native collection terminates or deallocates.
- Components NEVER store long-lived strong references to native view controllers, views, or Swift delegates inside shared Kotlin StateFlow or CoroutineContext elements.

## Bad vs Good Implementations
### Unbounded Coroutine Scope vs. Lifecycle-Managed Swift Bridge (Kotlin/Swift)

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Launching from an unbound CoroutineScope without linking to platform view lifecycles causes jobs to survive screen dismissal. On iOS, Kotlin/Native ARC-to-tracing GC bridges will leak the ViewModel closure and continue executing zombie network requests.
```kotlin
// Shared KMP Code
class UserProfileViewModel {
    // ANTI-PATTERN: Global unmanaged scope. No lifecycle attachment, leaks on iOS
    private val scope = CoroutineScope(Dispatchers.Default)

    fun loadUserProfile(userId: String) {
        scope.launch {
            val profile = repository.fetchRemoteProfile(userId)
            notifyListeners(profile)
        }
    }
}

// Swift Native Consumer (iosApp)
// class UserProfileView: ObservableObject {
//     func onAppear() {
//         // Invocations keep running even after View is popped/dismissed,
//         // causing background network mutations and retain cycles.
//         viewModel.loadUserProfile(userId: "123")
//     }
// }
```

#### Production Standard (Correct)
> **Standard**: Provides a clean, lifecycle-aware CoroutineScope anchored to a SupervisorJob. Propagates explicit cancellation when the view transitions out of scope, purging jobs immediately and releasing both Kotlin and Swift reference graphs.
```kotlin
// Shared KMP Code (Kotlin 2.1)
open class LifecycleViewModel(dispatcher: CoroutineDispatcher = Dispatchers.Main.immediate) {
    private val job = SupervisorJob()
    val coroutineScope: CoroutineScope = CoroutineScope(job + dispatcher)

    fun clear() {
        job.cancel()
    }
}

class UserProfileViewModel : LifecycleViewModel() {
    private val _uiState = MutableStateFlow<UiState>(UiState.Loading)
    val uiState: StateFlow<UiState> = _uiState.asStateFlow()

    fun loadUserProfile(userId: String) {
        coroutineScope.launch {
            try {
                _uiState.value = UiState.Success(repository.fetchRemoteProfile(userId))
            } catch (ce: CancellationException) {
                throw ce // Structured concurrency preserved
            } catch (e: Throwable) {
                _uiState.value = UiState.Error(e.message)
            }
        }
    }
}

// Swift Native Bridge Pattern
// struct UserProfileView: View {
//     @StateObject private var vm = NativeViewModelWrapper(UserProfileViewModel())
//     var body: some View {
//         ContentView()
//             .task { vm.wrapped.loadUserProfile(userId: "123") }
//             .onDisappear { vm.wrapped.clear() } // Cancels Job cascade deterministically
//     }
// }
```
Recommended MCP Servers (mcp-serverlist.com)

Equip agent with system tools to verify code for this stack.

Kotlin Language Server MCP
Validates Kotlin 2.1 compiler diagnostics, type-checking, and coroutines scope bindings.
Recommended Agent Skills (askills.dev)

Ready-to-use executable skill functions tailored to this stack.

KMP Native Leak Checker
CLI automation checking for dangling CoroutineScopes and Swift/Kotlin reference cycles.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary

Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary defines an industrial-grade behavioral standard for mobile engineering. Mandates strict lifecycle-bound CoroutineScope termination and bidirectional cancellation propagation across Android ViewModels and Swift/Objective-C interop runtimes. Prohibits detached jobs, unbound GlobalScope invocations, and manual un-bridged async calls to eliminate native heap leaks, uncollected Kotlin/Native reference graphs, and zombie network dispatches. Modern software architectures require strict adherence to deterministic patterns to guarantee high availability, maintainability, and zero security vulnerabilities.

Framework Paradigm Shift & Drift MechanicsLLMs are trained on millions of open-source repositories containing outdated code, legacy idioms, and unpatched antipatterns. When coding assistants generate implementations for this stack, they default to common statistical tokens: Unbound Coroutine Bridging Yielding Zombie Tasks and Swift/Native Memory Leaks Without an explicit system instruction file, developers spend hours debugging silent failures.
Failure Modes & Production Blast Radius

Hazard Analysis: What Breaks Without This Rule

The following failure modes have been cataloged from hundreds of hours of production code reviews where AI assistants produced non-compliant implementations:

Failure ModeAI Symptom (The Anti-Pattern)SeverityProduction Impact & Remedy
AI Hallucination & Deprecation DriftUnbound Coroutine Bridging Yielding Zombie Tasks and Swift/Native Memory LeaksCritical
Violating this industrial standard introduces regression bugs, security risks, and unexpected runtime failures in production.
Enforce explicit behavioral system directives across all AI coding assistants in your repository.
Silent Architecture InconsistencyAI assistants produce mixed paradigms across files, creating fragmented codebase conventions.Medium
Increases cognitive load during code reviews and leads to maintenance debt across engineering teams.
Pin project conventions in .cursor/rules, CLAUDE.md, and AGENTS.md so all team agents follow identical guardrails.
Architectural Directives in Detail

Step-by-Step Production Directives

Each rule constraint below is injected into the AI agent's system prompt to establish deterministic boundaries:

1

Engineers MUST ALWAYS bind shared Kotlin Multiplatform CoroutineScope instances to platform lifecycle abstractions (Android ViewModel `viewModelScope` and iOS `deinit` / SwiftUI `.task` hooks).

Engineers MUST ALWAYS bind shared Kotlin Multiplatform CoroutineScope instances to platform lifecycle abstractions (Android ViewModel `viewModelScope` and iOS `deinit` / SwiftUI `.task` hooks).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
2

Engineers MUST NOT expose unbounded suspending functions or unmanaged `GlobalScope` dispatches to Swift

Engineers MUST NOT expose unbounded suspending functions or unmanaged `GlobalScope` dispatches to Swift; wrap scopes in explicit cancellation boundaries (e.g., `Closeable` or `Job.cancel()` handles).

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
3

Code MUST bridge Swift structured concurrency cancellation directly to Kotlin coroutine `Job.cancel()` using `withTaskCancellationHandler` or SKIE/KMP-native lifecycle wrappers.

Code MUST bridge Swift structured concurrency cancellation directly to Kotlin coroutine `Job.cancel()` using `withTaskCancellationHandler` or SKIE/KMP-native lifecycle wrappers.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
4

Services MUST ensure that all streaming flows exposed across the Kotlin/Native boundary cancel upstream producers when native collection terminates or deallocates.

Services MUST ensure that all streaming flows exposed across the Kotlin/Native boundary cancel upstream producers when native collection terminates or deallocates.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
5

Components NEVER store long-lived strong references to native view controllers, views, or Swift delegates inside shared Kotlin StateFlow or CoroutineContext elements.

Components NEVER store long-lived strong references to native view controllers, views, or Swift delegates inside shared Kotlin StateFlow or CoroutineContext elements.

Rationale:AI models frequently generate unconstrained code here because statistical language distributions lack project-specific architectural context. Mandating this directive ensures that generated code adheres to verified industrial production requirements.
Enforcement:Integrated into the Agent Pack rule file. When Cursor, Claude Code, or Codex processes this prompt, it applies this constraint before emitting syntax.
Technical Questions & Answers

Frequently Asked Technical Questions

Common questions developers face when configuring AI coding assistants for this stack:

Q:Why is Kotlin Multiplatform 2.1 Structured Concurrency & Native Lifetime Cancellation Boundary critical for AI coding assistants?

Mandates strict lifecycle-bound CoroutineScope termination and bidirectional cancellation propagation across Android ViewModels and Swift/Objective-C interop runtimes. Prohibits detached jobs, unbound GlobalScope invocations, and manual un-bridged async calls to eliminate native heap leaks, uncollected Kotlin/Native reference graphs, and zombie network dispatches. Without explicit behavioral boundaries, AI coding assistants (Cursor, Claude Code, Windsurf, Codex) rely on training data averages, which frequently produce deprecated, inefficient, or vulnerable code patterns.

Q:How does adopting this rule prevent AI hallucinations?

This rule explicitly declares what the AI must avoid (Unbound Coroutine Bridging Yielding Zombie Tasks and Swift/Native Memory Leaks) and prescribes verified positive examples. Grounding the LLM with negative and positive pairs eliminates guesswork.

Q:Which AI coding environments are supported?

This specification is multi-platform compatible: Cursor (.cursor/rules/*.mdc & .cursorrules), Anthropic Claude Code (CLAUDE.md), Windsurf (.windsurfrules), Codex / Cline (AGENTS.md), and GitHub Copilot (.github/copilot-instructions.md).

Q:Can I combine this rule with other technology stacks?

Yes. Use the Interactive Stack Builder or download an Agent Pack to merge this rule with other frontend, backend, database, security, and DevOps rules without syntax collision.

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