@phcdevworks/spectre-shell-signals

Repository Snapshot

Field	Value
Project team	project-shell
Repository role	Spectre reactive primitives
Package/artifact	@phcdevworks/spectre-shell-signals
Current version/status	1.1.0

Standard Workflow

1. Read AGENTS.md, then the agent-specific guide for the task.
2. Check TODO.md and ROADMAP.md for current scope.
3. Make the smallest repo-local change that satisfies the task.
4. Run npm run check when validation is required or practical.
5. Update docs and CHANGELOG.md only when behavior, public contracts, or release-relevant metadata changed.

Documentation Map

Guide	Path
Agent rules	AGENTS.md
Claude Code	CLAUDE.md
Codex	CODEX.md
Copilot	COPILOT.md
Jules	JULES.md
Roadmap	ROADMAP.md
Todo	TODO.md
Changelog	CHANGELOG.md
Security	SECURITY.md

Small synchronous reactive primitives for Spectre packages. The package provides signal, computed, and effect without tying Spectre runtime code to a UI framework.

Part of the PHCDevworks Spectre shell ecosystem — composable, zero-dependency packages for client-side shell applications.

Contributing | Changelog | Roadmap | Security Policy

When to use this package

• You need synchronous reactive primitives (signal, computed, effect) without a full state management framework.
• You want typed, lazily-evaluated derived values with explicit disposal.
• You are building on top of a Spectre shell or want framework-agnostic reactive state in vanilla TypeScript.

When not to use this package

• You need a global store, atoms, selectors, or async resource primitives.
• You need framework-specific hooks such as useSignal for React or Vue.
• You need persistence, devtools, observables, event buses, or middleware.
• You need cross-component state coordination patterns beyond sharing signal instances.

Capabilities

• Mutable signals through a .value getter and setter, and a .peek() method for untracked reads.
• Lazily evaluated computed values with dependency tracking.
• Synchronous effects with cleanup registration.
• Explicit disposal for computed values and effects.
• A deliberately small public API for shared Spectre runtime state.

Install

npm install @phcdevworks/spectre-shell-signals

Quick Start

import { computed, effect, signal } from '@phcdevworks/spectre-shell-signals'

const count = signal(0)
const doubled = computed(() => count.value * 2)

const stop = effect((onCleanup) => {
  console.log(`count=${count.value}; doubled=${doubled.value}`)
  onCleanup(() => console.log('effect cleanup'))
})

count.value = 2
stop()
doubled.dispose()

API

• signal(initialValue) returns a mutable signal with .value (tracked read/write) and .peek() (untracked read).
• computed(fn) returns a cached computed value with dispose().
• effect(fn, options?) runs immediately, reruns when tracked dependencies change, and returns a stop function. Pass { onError } to handle errors without stopping the effect.
• batch(fn) defers subscriber notification until fn returns, so effects run once per batch rather than once per write.
• Types include Signal, Computed, EffectCallback, EffectCleanup, EffectOptions, CleanupRegistrar, and StopEffect.

signal.peek()

peek() reads the current value without registering the caller as a subscriber. Use it inside an effect or computed body when you need the value but do not want to re-run the observer when it changes.

const count = signal(0)

effect(() => {
  // re-runs whenever `flag` changes, but NOT when `count` changes
  if (flag.value) {
    console.log(count.peek())
  }
})

Effect error boundary

Pass onError to handle errors thrown inside an effect without stopping the reactive chain. The effect stays active and re-runs normally when its next dependency changes.

const count = signal(0)

const stop = effect(
  () => {
    if (count.value === 1) throw new Error('bad state')
    console.log(count.value)
  },
  { onError: (err) => console.error('effect error:', err) }
)

count.value = 1 // onError fires, effect stays alive
count.value = 2 // logs 2 normally
stop()

Without onError, errors propagate synchronously to the caller — the initial run throws from effect(), and re-run errors throw from the signal setter.

Ecosystem

spectre-shell-signals is the reactive primitive foundation for the Spectre stack:

Package	Role
spectre-shell-signals	Reactive primitives (signal, computed, effect)
spectre-tokens	Visual language and token contracts (reactive token values)
spectre-ui	Token-driven styling and class recipes (reactive component state)
spectre-ui-astro	Astro component layer (island lifecycle integration)

Consuming packages depend on this package for reactive state. They do not re-export its primitives or extend its API.

Boundaries

This package owns only low-level reactive primitives. It does not own DOM rendering, routing, lifecycle orchestration, async scheduling, stores, persistence, or framework adapters.

Development

npm install
npm run check

Useful scripts:

• npm run typecheck validates TypeScript without emitting files.
• npm run lint runs ESLint.
• npm run test runs the Vitest suite once.
• npm run build emits ESM, CJS, and declarations to dist.
• npm run check runs the standard package verification flow.

AI-agent coordination starts in AGENTS.md, with companion guidance in CLAUDE.md, CODEX.md, COPILOT.md, JULES.md, and .github/copilot-instructions.md.

Troubleshooting

Problem	Likely cause	Fix
npm run check fails on typecheck	Type error in source or tests	Run npm run typecheck to isolate
dist/ is missing after clone	Build output is gitignored	Run npm run build
Tests fail in CI but pass locally	Node version mismatch	CI runs Node 22 and 24; match locally
Effect runs more than expected	Unintended .value read in tracked scope	Move non-reactive reads outside the effect callback

Contributing

See CONTRIBUTING.md. The gate is npm run check — typecheck, lint, build, test, and ecosystem validation must all pass. Do not expand the reactive-primitives scope; see AGENTS.md for boundaries.

Release Notes

See CHANGELOG.md.

License

MIT. See LICENSE.