Qwik City Resumability & Containerization Production Standard

--- description: Qwik City Resumability & Containerization Production Standard - Enforces Qwik's zero-hydration resumability model by strictly isolating lexical boundaries across Optimizer-split chunk closures. Prevents accidental closure captures, serialization bottlenecks, and eager code evaluation that degrade instant-on performance. Failure to maintain clean serializable boundaries introduces runtime de-opt failures, memory leaks, and massive client bundle bloat. globs: src/**/*.{ts,tsx}, src/routes/**/*.{ts,tsx}, src/components/**/*.{ts,tsx} alwaysApply: true verified_by: "agentrules.org" license: "CC-BY-4.0" source: "https://agentrules.org/rules/qwik-city-resumability-containerization-production-standard" --- # Qwik City Resumability & Containerization Production Standard > **Severity**: CRITICAL | **Category**: frontend > **Anti-Pattern Warning**: Capturing non-serializable runtime instances inside '$' closures or eagerly importing heavy client modules without QRL boundaries. ## System Constraints You are a Principal Qwik and Qwik City architect. You MUST enforce zero-hydration resumability, strict QRL ($) boundary semantics, and serializable state across server-to-client handoffs. NEVER allow capture of non-serializable objects (DOM nodes, class instances, closures) inside QRL scopes. ## Strict Guidelines - Developers MUST NOT capture non-serializable objects (such as complex class instances, window/document references, or function closures) within '$' QRL boundaries. - All persistent component state MUST be managed using 'useSignal' or 'useStore' with primitive or plain serializable record structures to maintain zero-hydration resumes. - Client-only browser APIs MUST be guarded inside 'useVisibleTask$' or dynamically imported via QRL boundaries, and developers SHOULD prefer 'useTask$' with 'isServer' checks for data-fetching invariants. - Event listeners and callbacks MUST ALWAYS use the '$' suffix (e.g., 'onClick$') to allow the Qwik Optimizer to break execution trees into fine-grained lazy-loaded chunks. - Heavy external libraries MUST NEVER be eagerly imported at the top-level of route modules; developers MUST dynamically import them inside '$' closures or server actions. ## Bad vs Good Implementations ### Preventing Non-Serializable Class Capture & Eager Heavy Execution in Event Handlers #### Bad Antipattern (AI Common Hallucination) > **Why it fails**: The component captures an instantiated class ('AnalyticsTracker') inside an 'onClick$' boundary, triggering a Qwik serialization runtime error. Additionally, eagerly importing 'Chart' bundles the entire charting library into the critical path instead of lazy-loading it upon user interaction. ```typescript import { component$, useSignal } from '@builder.io/qwik'; import { Chart } from 'chart.js/auto'; // Eagerly loads full library into main bundle class AnalyticsTracker { send(event: string) { navigator.sendBeacon('/api/log', JSON.stringify({ event })); } } export const BadChartComponent = component$(() => { const chartRef = useSignal<HTMLCanvasElement>(); const tracker = new AnalyticsTracker(); // Non-serializable class instance return ( <div> <canvas ref={chartRef} /> <button onClick$={() => { // ERROR: Capturing 'tracker' breaks serialization during resumability tracker.send('chart_clicked'); // ERROR: Direct Chart instantiation breaks Optimizer lazy-loading if (chartRef.value) { new Chart(chartRef.value, { type: 'bar', data: { datasets: [] } }); } }} > Initialize Chart </button> </div> ); }); ``` #### Production Standard (Correct) > **Standard**: The improved code isolates heavy third-party code via dynamic import inside a QRL scope, relies on serializable primitives for state ('isRendering'), and delegates telemetry to an isolated 'server$' endpoint, preserving instant zero-hydration resumability. ```typescript import { component$, useSignal, $ } from '@builder.io/qwik'; import { server$ } from '@builder.io/qwik-city'; // Pure serializable RPC for logging without bundling local classes const logEventServer = server$((event: string) => { console.info(`Server-logged telemetry: ${event}`); }); export const GoodChartComponent = component$(() => { const chartCanvasRef = useSignal<HTMLCanvasElement>(); const isRendering = useSignal<boolean>(false); const handleInitialize$ = $(async () => { if (!chartCanvasRef.value || isRendering.value) return; isRendering.value = true; try { // Lazily import heavy dependency only when event fires const { Chart } = await import('chart.js/auto'); new Chart(chartCanvasRef.value, { type: 'bar', data: { datasets: [] }, }); await logEventServer('chart_rendered'); } finally { isRendering.value = false; } }); return ( <div> <canvas ref={chartCanvasRef} /> <button disabled={isRendering.value} onClick$={handleInitialize$} > {isRendering.value ? 'Loading...' : 'Initialize Chart'} </button> </div> ); }); ```

Architectural Specification & Invariant Rationale

Architectural Invariant Design: Qwik City Resumability & Containerization Production Standard

Qwik City Resumability & Containerization Production Standard defines an industrial-grade behavioral standard for frontend engineering. Enforces Qwik's zero-hydration resumability model by strictly isolating lexical boundaries across Optimizer-split chunk closures. Prevents accidental closure captures, serialization bottlenecks, and eager code evaluation that degrade instant-on performance. Failure to maintain clean serializable boundaries introduces runtime de-opt failures, memory leaks, and massive client bundle bloat. 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: Capturing non-serializable runtime instances inside '$' closures or eagerly importing heavy client modules without QRL boundaries. 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 Mode	AI Symptom (The Anti-Pattern)	Severity	Production Impact & Remedy
AI Hallucination & Deprecation Drift	Capturing non-serializable runtime instances inside '$' closures or eagerly importing heavy client modules without QRL boundaries.	Critical	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 Inconsistency	AI 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:

Developers MUST NOT capture non-serializable objects (such as complex class instances, window/document references, or function closures) within '$' QRL boundaries.

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.