qwik-core-development

# Qwik Core Development Use this skill for `packages/qwik/**` work. Keep the normal repo-wide instructions from `.ruler/AGENTS.md` in force. ## Fast Path 1. Identify the touched subsystem before editing: reactive primitives, VNode/client diffing, cursor, QRL/serialization, SSR, hooks, or tests. 2. Read the smallest relevant source and tests before making changes. 3. Find the invariant that must stay true across SSR, resume, client render, and serialization when the touched code crosses those boundaries. 4. After implementation changes, immediately run the closest focused Vitest file with `pnpm vitest run <path>`. Do not use `pnpm test.unit`. 5. If touching Rust optimizer code, load `qwik-optimizer-development` instead of treating the change as TypeScript-only. ## When to Load Detailed Notes Read `references/core-notes.md` only when the task involves: - async signals, computed signals, polling, or signal invalidation; - QRL creation, `$` transform behavior, or serialization issues; - VNode, cursor, or DOM diff behavior; - Qwik core tests that use `$()`, `retryOnPromise`, or private runtime state; - an unfamiliar pattern in `packages/qwik/src/core`. Do not load the reference for simple docs, package metadata, formatting, or unrelated monorepo work. ## Core Reminders - Prefer existing Qwik runtime patterns over new abstractions. - Keep state ownership explicit. For serialized or streamed data, update emit and consume paths together and add a round-trip or regressio...