> ## Documentation Index
> Fetch the complete documentation index at: https://java.agentscope.io/llms.txt
> Use this file to discover all available pages before exploring further.

# What's AgentScope 2.0?

> Harness engineering, enterprise-grade distributed deployment, and a redesigned foundation.

AgentScope Java 2.0 is a major step up from a "build an agent" toolkit toward a complete platform for **running agents in production**. The improvements fall into three focus areas, each solving a distinct problem.

<Note>
  AgentScope Java 2.0 aims to preserve compatibility with 1.x where possible so that most users can upgrade smoothly, but it also introduces API-level breaking changes alongside significant improvements to the core abstractions, APIs, and architecture. See the [V1 Migration Guide](/v2/en/docs/change-log) for the full migration guide.
</Note>

## 1 · Harness Engineering — built for long-running, complex tasks

A bare ReAct loop solves one reasoning turn. Real-world tasks run for hours, accumulate state, and demand persistent skills. **Harness** builds the engineering scaffolding so agents stay reliable indefinitely, accrue capability, and finish complex jobs without manual context surgery — the reasoning core stays untouched, capabilities layer on.

<CardGroup cols={2}>
  <Card title="Self-evolution & skill repository" href="/v2/en/docs/harness/skill">
    Successful patterns are saved as Markdown skills in `workspace/skills/`, loaded per step and shared across sessions — know-how accumulates between runs.
  </Card>

  <Card title="Layered memory management" href="/v2/en/docs/harness/memory">
    Three tiers: in-context conversation, agent-curated `MEMORY.md`, and an on-disk fact log. Auto-compaction bounds the prompt; `memory_*` tools give explicit recall.
  </Card>

  <Card title="Sub-agents" href="/v2/en/docs/harness/subagent">
    Declare child agents in Markdown specs; run them sync or in the background via `agent_spawn` / `agent_send`. Background results push back via `system-reminder` — no polling.
  </Card>

  <Card title="Auto context management" href="/v2/en/docs/harness/compaction">
    Structured compaction preserves goals, state, findings, and next steps; oversized tool results offload to disk; context-overflow retry is the safety net.
  </Card>

  <Card title="Plan Mode for complex tasks" href="/v2/en/docs/harness/plan-mode">
    A read-only planning state for long tasks; plans persist under `workspace/plans/` and drive execution, keeping intent decoupled from action.
  </Card>

  <Card title="Workspace as the foundation" href="/v2/en/docs/harness/workspace">
    Persona, knowledge, skills, sub-agent specs, session logs — all on-disk Markdown / JSON, auto-injected into the prompt each turn.
  </Card>
</CardGroup>

## 2 · Enterprise-grade distributed deployment

Production agents must serve many tenants, run untrusted tool code safely, and survive rolling restarts without losing in-flight context. AgentScope 2.0 is built for **stateless horizontal scaling**: any replica can pick up the full context of any user, sandbox state resumes across processes, and permission gates plus multi-dimension isolation keep every tenant's data separate.

<CardGroup cols={2}>
  <Card title="Multi-tenant isolation" href="/v2/en/docs/building-blocks/context">
    Isolate state across `session` / `user` / `agent` / `org`. `RuntimeContext` keys flow through workspace paths, KV namespaces, and sandbox state slots.
  </Card>

  <Card title="Secure sandbox execution" href="/v2/en/docs/harness/sandbox">
    Tools execute in an isolated environment — local subprocess, Docker, or remote AgentRun — with snapshot/resume so long jobs survive restarts.
  </Card>

  <Card title="Tool permission control" href="/v2/en/docs/building-blocks/permission-system">
    Three-state engine (allow / approve / deny) over static rules, tool category, and input analysis. Sensitive tools require human approval — HITL is first-class.
  </Card>

  <Card title="Graceful start / stop & session recovery" href="/v2/en/docs/building-blocks/context">
    The same `(userId, sessionId)` resumes the full conversation on any process. `AgentStateStore` (in-memory / JSON file / MySQL / Redis) backs zero-downtime rolling deploys and crash recovery.
  </Card>
</CardGroup>

## 3 · Foundation framework — a leaner, more developer-friendly core

The bottom layer has been redesigned. Messages, events, and the extension model are now smaller, more orthogonal, and more pleasant to work with — and HITL plus event streaming are no longer add-ons grafted on top, they are part of how the framework runs.

<CardGroup cols={2}>
  <Card title="Event streaming, built in" href="/v2/en/docs/building-blocks/message-and-event">
    Every step — model call, text delta, tool execution, tool result — surfaces as a typed event on one stream. Subscribe once; your UI follows in real time.
  </Card>

  <Card title="A simpler message model" href="/v2/en/docs/building-blocks/message-and-event">
    Text, files, images, audio, video, thinking, tool results — all one `ContentBlock` shape. Role-strict construction catches malformed messages at build time.
  </Card>

  <Card title="Middleware, not hooks" href="/v2/en/docs/building-blocks/middleware">
    Five stages (`onAgent` / `onReasoning` / `onActing` / `onModelCall` / `onSystemPrompt`) replace v1's loose hooks. Each concern stays in its own layer and composes cleanly.
  </Card>

  <Card title="Human-in-the-loop, first class" href="/v2/en/docs/building-blocks/permission-system">
    Confirm tool arguments, approve sensitive actions, or hand off mid-run to an external system. The agent pauses and resumes exactly where it stopped — no scaffolding.
  </Card>
</CardGroup>

***

If you are still evaluating whether to migrate, the [V1 Migration Guide](/v2/en/docs/change-log) breaks down every change with a Migration Guide (must-do vs. recommended) and a What's New section — enough to plan an upgrade end-to-end. For per-version changes, see [Release Notes](/v2/en/docs/others/release-notes).

## AgentScope Service

[AgentScope Service: deployment and usage](/v2/en/service/index)