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Reactive Agents

What's New

A quick-scan guide to what has landed in each major release. Start here when returning after time away — each bullet links to the relevant documentation.

Current (post-v0.9.0)

Section titled “Current (post-v0.9.0)”

Features shipped to main since the v0.9.0 tag, not yet assigned a version number.

  • StatusRenderer TUI — live terminal display with collapsible think panel (t key toggles), mode: 'stream' | 'status' — see Observability
  • 3 new terminal tools — git-cli, gh-cli, and gws-cli are now built-in, bringing the total to 11 — see Tools
  • New web-search provider: Serper.dev — third web-search backend alongside Tavily; no extra config beyond SERPER_API_KEY — see Tools
  • crypto-price built-in tool — CoinGecko price lookup, no API key required, module-level cache — see Tools
  • Observability on by default — minimal verbosity is now enabled out of the box; no .withObservability() call needed for basic output — see Observability
  • Sub-agent maxIterations fully honored — the silent cap of 3 has been removed; your configured value is respected — see Sub-agents

v0.9.0 — MCP Production Hardening

Section titled “v0.9.0 — MCP Production Hardening”
  • MCP client rewritten on @modelcontextprotocol/sdk — smart auto-detection between stdio and HTTP-only containers, two-phase docker lifecycle — see Orchestration
  • Composable kernel architecture — react-kernel.ts reduced from ~1,700 to ~197 lines via makeKernel({ phases }) factory; phases are now individually swappable — see Composable Kernel
  • Permanently-failed required tools fix — tools that always error no longer cause loop-until-maxIterations; framework detects and stops early — see Harness Control Flow
  • Cortex MCP CRUD + JSON import — import Cursor/Claude-style MCP configs directly into Cortex — see Cortex
  • effect moved to peerDependencies — add effect explicitly if you import from it directly — see Installation

v0.8.5 — Native FC Hardening + Web Framework Adapters

Section titled “v0.8.5 — Native FC Hardening + Web Framework Adapters”
  • React, Vue, and Svelte adapters — useAgentStream() and useAgent() hooks/composables/stores for all three frameworks, consuming SSE endpoints — see Web Integration and Streaming
  • 7-hook provider adapter system — taskFraming, toolGuidance, errorRecovery, synthesisPrompt, qualityCheck, continuationHint, systemPromptPatch fully wired — see Reactive Intelligence
  • Dynamic stopping (3-layer) — novelty signal (Jaccard overlap), budget exhaustion phase transition, and per-tool call cap (maxCallsPerTool) — see Harness Control Flow
  • Full prompt observability — logModelIO: true logs the complete FC conversation thread with no truncation — see Observability
  • Actionable failure messages — loop detection, required-tools, and stall detection all emit Fix: suggestions with specific builder options — see Troubleshooting

v0.8.0 — Reactive Intelligence Layer

Section titled “v0.8.0 — Reactive Intelligence Layer”
  • Entropy-aware intelligence pipeline — 5-source composite entropy sensor, trajectory classifier, and reactive controller that takes corrective action automatically — see Reactive Intelligence
  • Thompson Sampling strategy learner — SQLite-backed bandit learns which reasoning strategy wins per task category across runs — see Reactive Intelligence
  • Builder hardening — withStrictValidation(), withTimeout(), withRetryPolicy(), withFallbacks(), withHealthCheck(), and withErrorHandler() — see Builder API
  • Automatic strategy switching — when entropy analysis detects a stuck loop, the agent switches reasoning strategy without user intervention — see Choosing Strategies
  • Observability dashboard upgrade — chalk/boxen terminal UI with entropy grade (A–F), sparklines, and entropy-informed alerts — see Observability

v0.5.0 — A2A Protocol + Observability Foundation

Section titled “v0.5.0 — A2A Protocol + Observability Foundation”
  • Full A2A (Agent-to-Agent) protocol — JSON-RPC 2.0 server, streaming SSE, client, discovery, and capability matching based on Google’s A2A spec — see A2A Protocol
  • Agent-as-tool pattern — wrap any local or remote A2A agent as a callable tool with createAgentTool() / createRemoteAgentTool() — see Sub-agents
  • Live observability streaming — withObservability({ live: true, verbosity }) writes structured phase logs to stdout as each step fires — see Observability
  • rax serve — expose any agent as an A2A-compliant HTTP server with a single CLI command — see CLI
  • EventBus reasoning events — all 5 strategies publish ReasoningStepCompleted; subscribe with agent.on() for custom monitoring — see Observability