v0.2.0

What's New in v0.2.0

This is a major release introducing the Agentic Rendering Protocol (ARP), a complete UI SDK rewrite, and significant runtime enhancements.

Agentic Rendering Protocol (ARP)

• New transport-agnostic protocol for agent-to-renderer communication
• WebSocket transport (/_arp/v1) with capability negotiation and auto-reconnect
• SSE transport preserved for backward compatibility — existing clients work unchanged
• ArpBridge() — single translation point from StreamChunk to ArpMessage
• ARP spec defined in spec/arp/ (protocol + component catalog)

New UI SDK (Lit Web Components)

• Complete rewrite from vanilla JS to Lit web components
• 12 built-in components: table, status-card, code-block, diff, key-value, progress, form, confirm, choices, chart, product-cards, group
• <haira-ui-renderer> — universal component renderer with fallback
• <haira-chat> — full chat interface with WebSocket + SSE dual transport
• Chat session persistence with history sidebar and session switching

Generative UI

• Agents render rich UI components via ui.* helpers in tool @render blocks
• ui.table(), ui.chart(), ui.status_card(), ui.key_value(), ui.progress(), ui.form(), ui.confirm(), ui.choices(), ui.code_block(), ui.diff(), ui.product_cards(), ui.group()
• Components automatically streamed to connected clients

MCP Support

• MCP Client: Connect to external MCP servers as tool providers
• MCP Server: Expose Haira tools via MCP protocol
• MCP over SSE: Server-Sent Events transport for MCP

Observability

• observe.langfuse() integration for LLM generation tracing
• Exporter interface for custom observability backends
• Auto-detection and tree-shaking of observability providers

New Standard Library Packages

• vector — Vector database operations (with local and Postgres backends)
• sqlite — SQLite store backend (auto-included for workflows/servers)
• langfuse — Langfuse observability exporter

Compiler & Language Enhancements

• Unit testing support with @test decorator
• Code formatter
• Enhanced type checker with better diagnostics
• Multi-file project support improvements
• LSP updates for better editor integration
• Workflow retry mechanism
• Environment variable enhancements

New Examples

• 25-embeddings.haira — Vector embeddings
• 26-rag.haira — Retrieval-Augmented Generation
• 27-structured-output.haira — Structured agent output
• 28-observe.haira — Observability with Langfuse
• 29-testing.haira — Unit testing

Proof of Concepts

• poc/data-explorer/ — Multi-source data explorer with Postgres, Algolia, Meilisearch

Infrastructure

• Project restructured: primitive/haira/ (core runtime), stdlib/ (tree-shaken packages)
• Tree-sitter grammar updates
• Makefile improvements

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Full Changelog: v0.1.1...v0.2.0