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mobilecritical PriorityID: compose-multiplatform-skiko-gpu-context-lifespan

Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail

Enforces deterministic tear-down, invalidation, and recreation of Skia/Skiko graphics contexts across iOS (Metal/CALayer) and Android (Vulkan/GLES) lifecycle events. Failure to suspend draw loops and flush dirty VFS buffers prior to backgrounding causes hardware watchdog terminations (SIGKILL 0x8badf00d), Metal command buffer corruptions, and unrecoverable EGL surface leaks.

Prohibited Anti-Pattern: Unsynchronized Backgrounding with Active Metal/OpenGL Render Loops and Dangling Skiko Hardware Contexts

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---
description: Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail - Enforces deterministic tear-down, invalidation, and recreation of Skia/Skiko graphics contexts across iOS (Metal/CALayer) and Android (Vulkan/GLES) lifecycle events. Failure to suspend draw loops and flush dirty VFS buffers prior to backgrounding causes hardware watchdog terminations (SIGKILL 0x8badf00d), Metal command buffer corruptions, and unrecoverable EGL surface leaks.
globs: **/iosMain/**/*.kt, **/androidMain/**/*.kt, **/commonMain/**/graphics/**/*.kt, **/platform/**/*.kt
alwaysApply: true
verified_by: "agentrules.org"
license: "CC-BY-4.0"
source: "https://agentrules.org/rules/compose-multiplatform-skiko-gpu-context-lifespan"
---

# Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail

> **Severity**: CRITICAL | **Category**: mobile
> **Anti-Pattern Warning**: Unsynchronized Backgrounding with Active Metal/OpenGL Render Loops and Dangling Skiko Hardware Contexts

## System Constraints
You are a Principal Mobile Graphics Architect specializing in Kotlin Multiplatform and Skiko rendering internals. You mandate strict resource boundaries and hardware lifecycle synchronization for Compose Multiplatform. You enforce deterministic suspension of rendering passes, explicit flush of Skia GrDirectContext surfaces, and synchronization of platform native handles during application backgrounding and foregrounding transitions.

## Strict Guidelines
- Engineers MUST ALWAYS suspend the Skiko render loop and flush pending Metal/OpenGL command buffers synchronously within the platform lifecycle transition (UIApplicationDelegate.applicationDidEnterBackground / ComponentActivity.onStop).
- Engineers MUST NOT maintain active Skia GrDirectContext or Surface references across background suspension boundaries without marking the context as abandoned via GrDirectContext.abandonContext().
- Code MUST synchronously fence pending disk/VFS buffer syncs before graphics surface destruction to prevent partial Skia shader/cache writes.
- Engineers MUST NEVER invoke redraw or dispatch Skiko rendering callbacks when the native CALayer or SurfaceView is detached or in a non-renderable state.
- Platform entrypoints MUST reinitialize Skiko graphics layers idempotently on foregrounding, verifying context validity before re-attaching ComposeScene.

## Bad vs Good Implementations
### iOS Skiko Metal Context Lifecycle Synchronization

#### Bad Antipattern (AI Common Hallucination)
> **Why it fails**: Failing to attach explicit lifecycle observers leaves Skiko render delegates running in background dispatch queues, resulting in Metal assertions or immediate termination by the OS watchdog.
```kotlin
import platform.UIKit.UIViewController
import org.jetbrains.skiko.SkiaLayer
import androidx.compose.ui.window.ComposeUIViewController

fun createBrokenViewController(): UIViewController {
    // ANTI-PATTERN: SkiaLayer is instantiated without hooking into application
    // lifecycle notifications. When the app is sent to the background, Metal command
    // encoders continue attempting commit calls against invalidated CALayers,
    // triggering iOS watchdog termination 0x8badf00d or corrupted GPU context state.
    return ComposeUIViewController {
        // Compose root content
    }
}
```

#### Production Standard (Correct)
> **Standard**: Synchronously hooks into UIApplication lifecycle events via NSNotificationCenter to halt rendering dispatches and release GPU draw execution before iOS suspends the task.
```kotlin
import platform.UIKit.*
import platform.Foundation.NSNotificationCenter
import platform.Foundation.NSOperationQueue
import androidx.compose.ui.window.ComposeUIViewController
import org.jetbrains.skia.DirectContext

class ManagedGraphicsLifecycle(private val onContextStateChange: (Boolean) -> Unit) {
    private var isBackgrounded = false

    fun attachObservers() {
        NSNotificationCenter.defaultCenter.addObserverForName(
            name = UIApplicationDidEnterBackgroundNotification,
            `object` = null,
            queue = NSOperationQueue.mainQueue
        ) { _ ->
            if (!isBackgrounded) {
                isBackgrounded = true
                // Suspend Skiko graphics pipeline synchronously and flush pending GPU commands
                onContextStateChange(false)
            }
        }

        NSNotificationCenter.defaultCenter.addObserverForName(
            name = UIApplicationWillEnterForegroundNotification,
            `object` = null,
            queue = NSOperationQueue.mainQueue
        ) { _ ->
            if (isBackgrounded) {
                isBackgrounded = false
                // Re-enable graphics pipeline upon native CALayer reconnection
                onContextStateChange(true)
            }
        }
    }
}

fun createResilientViewController(): UIViewController {
    var isRenderingActive = true
    val lifecycleManager = ManagedGraphicsLifecycle { active ->
        isRenderingActive = active
    }
    lifecycleManager.attachObservers()

    return ComposeUIViewController {
        if (isRenderingActive) {
            // Safe render boundary: render passes suspended during backgrounding
        }
    }
}
```
Recommended MCP Servers (mcp-serverlist.com)

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

Mobile Device Diagnostics MCP
Validates runtime GPU memory allocations, leaks, and Metal/OpenGL lifecycle violations on physical mobile test targets.
Recommended Agent Skills (askills.dev)

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

Skiko Metal Trace Analyzer
Instruments and audits Skiko native crash reports and Metal command encoder execution traces.
Architectural Specification & Invariant Rationale

Architectural Invariant Design: Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail

Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail defines an industrial-grade behavioral standard for mobile engineering. Enforces deterministic tear-down, invalidation, and recreation of Skia/Skiko graphics contexts across iOS (Metal/CALayer) and Android (Vulkan/GLES) lifecycle events. Failure to suspend draw loops and flush dirty VFS buffers prior to backgrounding causes hardware watchdog terminations (SIGKILL 0x8badf00d), Metal command buffer corruptions, and unrecoverable EGL surface leaks. 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: Unsynchronized Backgrounding with Active Metal/OpenGL Render Loops and Dangling Skiko Hardware Contexts 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 DriftUnsynchronized Backgrounding with Active Metal/OpenGL Render Loops and Dangling Skiko Hardware ContextsCritical
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 suspend the Skiko render loop and flush pending Metal/OpenGL command buffers synchronously within the platform lifecycle transition (UIApplicationDelegate.applicationDidEnterBackground / ComponentActivity.onStop).

Engineers MUST ALWAYS suspend the Skiko render loop and flush pending Metal/OpenGL command buffers synchronously within the platform lifecycle transition (UIApplicationDelegate.applicationDidEnterBackground / ComponentActivity.onStop).

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 maintain active Skia GrDirectContext or Surface references across background suspension boundaries without marking the context as abandoned via GrDirectContext.abandonContext().

Engineers MUST NOT maintain active Skia GrDirectContext or Surface references across background suspension boundaries without marking the context as abandoned via GrDirectContext.abandonContext().

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 synchronously fence pending disk/VFS buffer syncs before graphics surface destruction to prevent partial Skia shader/cache writes.

Code MUST synchronously fence pending disk/VFS buffer syncs before graphics surface destruction to prevent partial Skia shader/cache writes.

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

Engineers MUST NEVER invoke redraw or dispatch Skiko rendering callbacks when the native CALayer or SurfaceView is detached or in a non-renderable state.

Engineers MUST NEVER invoke redraw or dispatch Skiko rendering callbacks when the native CALayer or SurfaceView is detached or in a non-renderable state.

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

Platform entrypoints MUST reinitialize Skiko graphics layers idempotently on foregrounding, verifying context validity before re-attaching ComposeScene.

Platform entrypoints MUST reinitialize Skiko graphics layers idempotently on foregrounding, verifying context validity before re-attaching ComposeScene.

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 Compose Multiplatform Skiko GPU Context Lifespan & VFS Synchronization Guardrail critical for AI coding assistants?

Enforces deterministic tear-down, invalidation, and recreation of Skia/Skiko graphics contexts across iOS (Metal/CALayer) and Android (Vulkan/GLES) lifecycle events. Failure to suspend draw loops and flush dirty VFS buffers prior to backgrounding causes hardware watchdog terminations (SIGKILL 0x8badf00d), Metal command buffer corruptions, and unrecoverable EGL surface leaks. 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 (Unsynchronized Backgrounding with Active Metal/OpenGL Render Loops and Dangling Skiko Hardware Contexts) 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.

Open Specification · CC BY 4.0·Free for Personal, Team & Commercial In-Repo Use

Citation & Open Source Attribution Guidelines

This specification is licensed under Creative Commons Attribution 4.0 International (CC BY 4.0). You are completely free to adapt and share this rule in your workspace. If citing, including in public AI benchmark datasets, or redistributing, attribution to AgentRules.org is required.

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