v0.1.9

Release Date: January 17, 2026

This release brings major improvements to Hot Module Replacement (HMR) stability and completes the Svelte 5 Runes integration, making Pulse more robust for modern development workflows.

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New Features

HMR-Safe Auto-Naming System

Pulse now automatically assigns stable, location-based names to unnamed sources and guards, preventing duplicates during HMR reloads.

How it works:

• Unnamed units receive auto-generated names based on their source location (e.g., source@react-example:7)
• Names remain stable across HMR reloads, even when code changes
• Automatic cleanup of stale units after HMR using generation-based tracking

Example:

// Before: Would duplicate on HMR
const count = source(0);

// Now: Automatically named as "source@MyComponent:5"
// Stable across HMR reloads

Generation-Based Cleanup

The registry now tracks unit “generations” and automatically removes orphaned units after HMR:

• Each HMR reload increments the generation counter
• Units from previous generations are cleaned up after 100ms
• Console logs show cleanup activity: [Pulse] Cleaned up X stale units after HMR

Performance Optimizations

• Stack Trace Caching: Auto-naming now uses a cache to avoid repeated stack trace parsing
• Lazy Evaluation: Names are only generated when needed, reducing overhead
• 10k sources test: Maintains performance (~2.3s) with minimal production overhead

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Svelte 5 Runes Integration

Complete Runes Support

@pulse-js/svelte now provides first-class support for Svelte 5’s Runes system:

Native Reactivity:

<script lang="ts">
  import { source } from "@pulse-js/core";
  import { usePulse } from "@pulse-js/svelte";

  const countSource = source(0);
  const count = usePulse(countSource);
</script>

<button onclick={() => countSource.update(n => n + 1)}>
  Count: {count.value}
</button>

Guard Integration:

<script lang="ts">
  import { useGuard } from "@pulse-js/svelte";
  import { authGuard } from "./logic";

  const state = useGuard(authGuard);
</script>

{#if state.status === "ok"}
  <p>Welcome, {state.value.name}</p>
{:else if state.status === "fail"}
  <p style="color: red">Error: {state.reason}</p>
{/if}

Improved Type Inference

• Reordered usePulse overloads to prioritize Guard<T> over Source<T>
• Fixed TypeScript errors like Property 'status' does not exist
• Adopted Svelte 5 prop patterns to eliminate state_referenced_locally warnings

Package Resolution Fixes

• Updated package.json exports to correctly map Svelte 5 Runes entry points
• Added optimizeDeps.exclude guidance for Vite configuration
• Fixed .svelte.js output alignment with tsup build process

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Improvements

Core (@pulse-js/core v0.1.9)

• Global Singleton Registry: Uses globalThis to persist across HMR reloads
• Auto-Naming Cache: Reduces stack trace parsing overhead
• SSR Hydration: Restored _hydrate method for proper server-side rendering support

Tools (@pulse-js/tools v0.1.7)

• Improved Display: Auto-generated names now show in DevTools with clean format
• Better Tracking: Uses stable IDs for editing unnamed sources
• HMR Awareness: DevTools correctly updates when units are replaced during HMR

Framework Integrations

React (@pulse-js/react v0.1.7)

• Updated dependencies to use latest core and tools

Vue (@pulse-js/vue v0.1.2)

• Updated dependencies to use latest core and tools

Svelte (@pulse-js/svelte v0.1.2)

• Complete Svelte 5 Runes integration
• Backward compatibility with Svelte 4 via usePulseStore
• Proxy-based Guards for stable object identity
• Updated documentation with Runes examples

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Bug Fixes

• Fixed SSR hydration test failure by restoring _hydrate method
• Resolved package resolution errors in Svelte 5 projects
• Fixed TypeScript inference issues in usePulse overloads
• Fixed HMR duplication when adding/removing names from sources

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Documentation

• Updated Svelte Integration guide with Runes examples
• Added Vite configuration instructions for Svelte 5
• Documented auto-naming behavior and HMR cleanup
• Added examples for both Runes and Store APIs

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Migration Guide

For Svelte users:

If you’re using Svelte 5, update your vite.config.ts:

import { defineConfig } from "vite";

export default defineConfig({
  resolve: {
    conditions: ["browser", "module", "jsnext:main", "jsnext"],
  },
  optimizeDeps: {
    exclude: ["@pulse-js/svelte"],
  },
});

Unnamed sources and guards will now automatically receive location-based names. This is transparent and requires no code changes, but you’ll see cleaner names in DevTools (e.g., source@MyComponent:7 instead of random IDs).