# Solid Reactivity Core Expert > Apply SolidJS fine-grained reactivity primitives with strict derivation-vs-side-effect rules. Use for signal/memo/effect/resource decisions and dependency correctness. Use when this capability is needed. - Skill: `tomevault-io/solid-reactivity-core-expert` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/solid-reactivity-core-expert` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/solid-reactivity-core-expert/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/solid-reactivity-core-expert --- # solid-reactivity-core-expert ## Trigger Use for reactivity correctness decisions involving `createSignal`, `createMemo`, `createEffect`, `createResource`, `batch`, `untrack`. ## Required Inputs - State ownership and mutation boundaries. - Current or planned derivations. - Side effects and async behavior. ## Workflow 1. Classify each reactive operation as state, derivation, side effect, or async boundary. 2. Replace effect-driven derivations with memo/signal derivations when possible. 3. Confirm dependency tracking is minimal and explicit. 4. Provide handoff notes to macro skill for implementation/refactor/review. ## Failure Modes - Unknown state ownership: require explicit owner boundary. - Effect loops detected: mark as blocking issue and propose memo-driven rewrite. - Async without loading/error semantics: add resource state matrix. ## Output Contract Return `DomainGuidanceOutput` with decisions, handoff steps, validation commands, and citations containing `doc_id`. ## Validation - `node tools/scripts/validate-skills.mjs --skill solid-reactivity-core-expert` - `node tools/scripts/validate-solid-corpus.mjs` ## Key Corpus References Use these `doc_id` values with the `read_corpus_doc` MCP tool: - `solid-core.reference.basic-reactivity.create-signal` — signal creation and update semantics - `solid-core.reference.basic-reactivity.create-memo` — derivation caching rules - `solid-core.reference.basic-reactivity.create-effect` — side-effect tracking and cleanup - `solid-core.reference.basic-reactivity.create-resource` — async reactive data loading - `solid-core.reference.reactive-utilities.batch` — grouped signal updates ## References - `../../references/solidjs/reactivity-core.md` - `../../references/solidjs-normalized/manifest.jsonl` - `../../references/solidjs-normalized/docs/reference/basic-reactivity/create-signal.md` - `../../references/solidjs-normalized/docs/reference/basic-reactivity/create-memo.md` - `../../references/solidjs-normalized/docs/reference/basic-reactivity/create-effect.md` --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/lvcoi) — claim your Tome and manage your conversions.