$ find your agent harness

MIT-licensed self-hosted personal AI assistant ('the lobster way') that exploded to ~382k GitHub stars in months: any model, 20+ messaging channels (WhatsApp/Telegram/Slack/iMessage...), SKILL.md skills via ClawHub, Docker-sandboxed sessions, cron jobs, voice, and a live Canvas.

Nous Research's MIT-licensed 'self-improving' server-resident agent (Feb 2026, ~211k stars): model-agnostic with persistent cross-session memory, autonomous skill creation compatible with the agentskills.io standard, DSPy/GEPA evolutionary self-optimization, and execution backends from local/Docker to Modal and Daytona.

The clean-room Rust/Python rewrite of Claude Code's harness architecture born hours after the March 31, 2026 source leak — reportedly the fastest-growing repo in GitHub history (~195k stars) with permission-gated tools, MCP, agent swarms, and container-first deployment — though the project is chaotic, largely agent-maintained, and its details vary across sources.

The most-starred open-source coding agent of 2026 (~183k stars, MIT, TypeScript): a polished terminal TUI with 75+ providers, LSP feedback, Tab-switchable build/plan agents plus background subagents, SKILL.md support, and optional paid model access via OpenCode Go ($10/mo) and pay-as-you-go Zen gateway.

Anthropic's Claude-only agent harness in native desktop form, redesigned April 14, 2026 around a multi-session sidebar for parallel agents across repos, with integrated terminal/editor/diff viewer, cloud-hosted 'Routines' that run on Anthropic infrastructure while your machine is off, and the ecosystem that originated Agent Skills, subagents, hooks, plugins, and the headless Agent SDK (repo is issue tracker/docs; stars 136,750).

Anthropic's terminal-native agentic coding tool and the category-defining harness, distinguished by its layered extensibility model (CLAUDE.md memory, Agent Skills, subagents, hooks, plugins, MCP) plus permission modes, checkpoints, and optional sandboxing, available from CLI/IDE/desktop/web with an Agent SDK for building on top.

Google's fully open-source (Apache-2.0) terminal agent with a generous free tier, distinguished by built-in Google Search grounding, an extensions ecosystem bundling prompts/MCP servers/commands, GEMINI.md context files, checkpointing, and real-time voice mode.

MIT-licensed Python library (103k stars) that lets any LLM drive a real Chrome browser via DOM+vision instead of brittle selectors, now flanked by a desktop app and a usage-based cloud with stealth browsers, proxies, and a 24/7 'Browser Use Box' agent.

OpenAI's open-source (Apache-2.0) Rust-rewritten terminal coding agent, distinguished by kernel-level OS sandboxing (Apple Seatbelt on macOS, Landlock/seccomp on Linux), a 272K-1M token context with GPT-5.x Codex models, MCP support, and cloud handoff to Codex web tasks.

High-performance Rust editor (GPL, hit 1.0 in 2026) whose Agent Panel offers a native agent with profiles/tool-permissions and MCP, but whose real differentiator is the open Agent Client Protocol (ACP) that lets external agents (Claude Code, Codex CLI, Gemini CLI, OpenCode — which bring their own skills support) render diffs natively in-editor, plus first-in-class native Parallel Agents (April 2026).

The dominant open-source VS Code agent (Apache-2.0, 64k+ stars, 1.5M+ installs): human-in-the-loop plan/act workflow with per-edit and per-command approval, terminal and browser control, an MCP marketplace, and a BYOK-first model with optional pay-as-you-go credits and an enterprise tier.

Warp is a Rust-based GPU-accelerated 'Agentic Development Environment' (terminal app, source opened April 2026 under dual MIT/AGPL) distinguished by running multiple agents in parallel — including hosting Claude Code, Codex, and Gemini CLI — plus Oz, its cloud orchestrator for autonomous background agents, with BYOK and credit-based pricing.

MIT-licensed Python framework (~55k stars) for role-based multi-agent 'Crews' plus event-driven 'Flows', with unified memory, hierarchical delegation, and a commercial AMP cloud platform (free tier, Pro from ~$25/mo, enterprise) that CrewAI says powered ~2B agentic executions in the year to January 2026.

Block's Rust-built, Apache-2.0 general engineering agent — now stewarded by the Linux Foundation's Agentic AI Foundation — distinguished by the deepest MCP integration in the ecosystem (70+ extensions, can also act as an MCP server) and shareable YAML 'Recipes' that scaled agent workflows to 60% of Block.

Low-level graph-based agent orchestration runtime with automatic checkpointing, durable execution, human-in-the-loop interrupts, and streaming (v1.2 in May 2026 added typed streaming, per-node timeouts, and distributed runtime), used in production by Klarna, LinkedIn, Uber, and Replit and serving as the substrate under Deep Agents.

The veteran model-agnostic IDE extension (VS Code + JetBrains, strong local-model support) that pivoted to 'Continuous AI' — a cn CLI running markdown-defined async agents as GitHub PR status checks — before being acquired by Cursor in 2026, with the original team shipping a final v2.0.0 (telemetry and auth removed).

MIT-licensed open-source VS Code fork positioned as the privacy-first Cursor alternative (direct BYOK to Claude/OpenAI/Gemini or local Ollama/DeepSeek/Qwen with no middleman, Agent/Gather/Chat modes, MCP, checkpoints), but development was paused in early 2026 — last binary June 2025, last code change August 2025 — and the GitHub repo is now archived, leaving maintenance to community forks.

Hugging Face's minimalist (~1,000-line core, Apache 2.0) 'agents that think in code' harness where the model writes executable Python as its action format instead of JSON tool calls, model-agnostic via transformers/Ollama/LiteLLM, with optional sandboxed execution (E2B, Docker, WebAssembly), managed sub-agents, and Hub sharing of tools and agents.

OpenAI's agent harness whose April 15, 2026 overhaul added a 'model-native harness' with Codex-like filesystem/shell tools, built-in compaction and memory, snapshot/rehydrate durable execution, handoffs, guardrails, tracing, and native sandbox execution via bring-your-own or built-in providers (E2B, Modal, Daytona, Cloudflare, Vercel, Blaxel, Runloop); non-OpenAI models supported via LiteLLM and Chat Completions-compatible endpoints.

The leading TypeScript agent framework (Apache 2.0 core since July 2025; some enterprise features commercial) offering agents, type-safe workflows with suspend/resume human-in-the-loop, memory, a unified router to 3,300+ models across ~94 providers, guardrails/scorers/tracing, Mastra Studio for interactive testing, and file-based agent definitions added July 2026.

LangChain's self-described 'batteries-included agent harness' (GA March 2026, ~26k stars) for long-running tasks, layering planning via write_todos, a virtual filesystem for context offloading, SKILL.md-compatible skills with progressive disclosure, subagent spawning, and LangGraph-store-backed long-term memory on top of the LangGraph runtime.

Alibaba's Apache-2.0 terminal agent (originally a Gemini CLI fork) optimized for Qwen3-Coder models, distinguished by broad provider flexibility (OpenAI/Anthropic/Gemini/Qwen APIs plus Ollama/vLLM local models), skills/subagents primitives, headless mode, and TypeScript/Python/Java SDKs.

Kilo's open-source terminal agent (Kilo CLI 1.0, built on the MIT-licensed OpenCode foundation) distinguished by support for 500+ models with zero-markup BYOK pricing, an MCP marketplace, and cross-surface continuity where a task can move between Slack, VS Code/JetBrains, cloud, and terminal.

The Cline/Roo merger-fork turned all-in-one agentic platform (~26k stars, 3M+ users): IDE extension, CLI, and hosted KiloClaw background agent reachable via Telegram/Discord/Slack, with 500+ models, mid-task model switching, an MCP marketplace, subagents (GA April 2026), and optional Kilo Pass credits from $19/mo.

The influential Cline fork that popularized multi-mode agents (Architect/Code/Debug/Ask) and orchestrated subtasks in VS Code — shut down May 15, 2026, with its Apache-2.0 repo archived on GitHub and Kilo Code recommended as the migration path.

Apache-2.0 platform for stateful agents descended from MemGPT, distinguished by tiered self-editing memory persisted in a database (core memory in-context, archival out-of-context) plus 2026 research on git-based 'Context Repositories' and memory-native RL; in 2026 the company is consolidating around Letta Code, an open, model-agnostic memory-first coding agent harness (LettaBot archived May 2026 and folded in as Channels).

MIT-licensed, type-safe Python agent framework from the Pydantic team with a FastAPI-like developer experience: schema-validated structured outputs, first-class MCP support, built-in OpenTelemetry observability (pairs with Logfire), and durable execution via native Temporal/DBOS integrations that offload model requests, tool calls, and MCP communication to fault-tolerant activities.

A batteries-included 2026 fork of Pi (created Dec 31, 2025; ~17k stars) that inverts Pi's minimalism: hash-anchored edits that reject stale patches, LSP and DAP debugger integration, in-process ripgrep/bash, 40+ providers, 32 tools, and subagent orchestration.

MIT-licensed open agent harness from HKU's Data Intelligence Lab (agent loop, tool registry, permission system, hooks, skills, plugins, MCP, React TUI, automatic context compression) built for clarity and Claude-style workflow compatibility, shipping with 'Ohmo', a built-in personal agent that runs on existing Claude Code/Codex subscriptions and works via Feishu/Slack/Telegram/Discord, autonomously branching, coding, testing, and opening PRs.

The AutoGen + Semantic Kernel convergence (1.0 GA April 2026) for .NET and Python, whose BUILD 2026 'Agent Harness' made production patterns first-class — shell/filesystem access, human-in-the-loop approvals, context compaction, todo tracking, plan/execute modes, AgentSkillsProvider skill discovery, and BackgroundAgentsProvider subagents — with hosted execution via Microsoft Foundry.

GitHub's terminal agent (GA February 2026) that brings the Copilot coding agent to the CLI, distinguished by deep GitHub.com integration (built-in GitHub MCP server, in-terminal Issues/PRs/Gists tabs), an Autopilot autonomous mode, custom .agent.md agents, multi-vendor model choice, and AI-credit-based billing.

Anthropic's production agent library exposing the same harness that powers Claude Code (tool loop, file/bash/web tools, subagents, hooks, skills, MCP, permission checkpoints) in Python and TypeScript; the MIT-licensed SDK wraps the bundled Claude Code runtime and, as of 2026, underpins Anthropic Managed Agents with separate metered billing from June 15, 2026.

AWS's Claude-powered agentic IDE (VS Code fork; launched internationally May 7, 2026 as the successor to Amazon Q Developer) whose signature is spec-driven development — generating requirements.md/design.md/tasks.md with EARS acceptance criteria before coding — plus event-driven agent hooks, steering files, AGENTS.md/Skills.md/MCP support, and 'Kiro Powers' pre-packaged AWS MCP servers; the GitHub repo (3,980 stars) is a public issue tracker, not the source.

Augment Code's terminal agent distinguished by its real-time Context Engine (semantic indexing of 1M+ files across repos, dependencies, docs, and git history), Unix-pipe-friendly print/quiet headless modes for CI/Lambda, custom slash commands, and credit-based plans from $20 (Indie) to enterprise.

Sourcegraph's opinionated no-model-picker coding agent (CLI + VS Code extension), distinguished by curated multi-model design with specialized subagents (Oracle for reasoning, Librarian for library research), Toolboxes (UNIX-script custom tools), skills with bundled MCP servers, and an ad-supported free mode alongside zero-markup pay-as-you-go credits.

Cursor's terminal/headless version of its IDE agent (shipped January 2026), distinguished by cloud handoff to isolated cloud VMs, sandboxed command execution with granular network/filesystem controls, hooks, async subagents, and shared MCP/rules/skills config with the Cursor editor.

Factory AI's agent-native development platform whose Droid CLI held top Terminal-Bench rankings (77.3% with GPT-5.3-Codex, Feb 2026), distinguished by deploying agents across CLI, IDEs, Slack, and Linear with broad multi-vendor model support including Chinese open-weight models; raised $150M at $1.5B in April 2026.

xAI's terminal coding agent (beta, launched June 5, 2026) distinguished by 8 parallel worktree-isolated subagents, a plan-first approval workflow, Arena Mode for competing outputs, an ACP-to-MCP bridge for MCP servers, OpenCode integration, and aggressive pricing via SuperGrok ($30/mo) and X Premium+ subscriptions.

VS Code-fork AI IDE whose Agent mode plus in-house Composer models, Background/Cloud Agents (isolated cloud VMs that report back as PRs), hooks, skills, and an agent SDK make it the most fully-built-out commercial agentic IDE; Composer 2 scored 61.7% on Terminal-Bench 2.0 and Composer 2.5 79.8% on SWE-bench Multilingual (SWE-bench Verified not reported).

The Windsurf AI IDE's Cascade agent, post-Cognition-acquisition, was rebranded to Devin Desktop (June 2, 2026) with Cascade deprecated (available through July 1, 2026) in favor of the Rust-rewritten 'Devin Local' agent (30% more token-efficient, subagents), pairing local agentic editing (Fast Context codebase awareness, MCP, Memories, Workflows) with Devin cloud sessions for background work.

Copilot's agent mode inside VS Code (extension itself MIT open-sourced; backend service proprietary) iterates on errors, runs tools/terminal, and applies multi-file edits, distinguished by deep GitHub-ecosystem reach: MCP support, SKILL.md Agent Skills (added April 2026), custom .agent.md agents, a multi-vendor model picker with Ollama BYOK, and a cloud 'coding agent' that works issues into PRs on GitHub Actions.

JetBrains' autonomous coding agent for IntelliJ-family IDEs (plus a Junie CLI that left beta March 2026 with BYOK/OpenRouter routing and CI/CD support), distinguished by leverage of the IDE's code index, a confirmation-gated loop with opt-in 'Brave Mode', Docker/worktree-isolated parallel tasks, remote cloud execution mode, and a companion Claude Agent built on Anthropic's Agent SDK.

ByteDance's VS Code-based AI IDE, notable for aggressive pricing (free tier plus $3-$100/mo token-based tiers, restructured Feb 2026) and the SOLO mode (standalone app since March 31, 2026) that acts as an end-to-end 'context engineer' handling requirements, code, terminal, browser testing and deployment, with MCP (stdio/SSE/streamable HTTP) and custom agents — but persistent privacy/telemetry concerns.

Google's agent-first development platform (launched Nov 2025, Antigravity 2.0 at I/O 2026 moved it toward a production standalone desktop app), distinguished by its Agent Manager 'mission control' that orchestrates parallel agents across editor, terminal, and an embedded browser subagent, with agents producing reviewable Artifacts (plans, screenshots, browser recordings) and a persistent knowledge/learnings base; runs Gemini 3 alongside Claude and GPT-OSS models.

The original 'AI software engineer': a cloud VM agent that plans, codes, tests and opens PRs from Slack/web/API, now spanning a whole product line (Devin cloud, Devin Desktop nee Windsurf, CLI) with ACU consumption billing ($2.00-2.25/ACU, Core $20 entry, Team $500/mo) and Cognition's own SWE-1.6 model alongside frontier models.

OpenAI's delegation-first coding agent whose cloud mode runs each task in an isolated no-internet-by-default sandbox with the repo cloned, opens PRs, does automatic PR code review on GitHub and takes tasks from ChatGPT/Slack, bundled into ChatGPT Plus/Pro/Business with rolling credit-based billing since April 2026 (the CLI companion is open source, the cloud service is not).

Cursor's fire-and-forget mode (formerly Background Agents): agents run in isolated cloud Ubuntu VMs — since Feb 2026 with a full desktop and browser for 'computer use' UI verification — clone the repo onto their own branch, work multi-repo in parallel, report back to the IDE/web/Slack/Teams/iOS app, and open PRs, with Dockerfile-configurable environments, scoped secrets, and a headless Background Agent API.

Enterprise-focused 'Droids' platform ($1.5B valuation after April 2026 Series C): autonomous agents that execute refactors, migrations and incident investigations end-to-end across CLI, desktop, SDK and remote 'Droid Computers' cloud workloads, with both local and cloud background agents on the $20 Pro tier and adoption at Nvidia, Adobe, Morgan Stanley and MongoDB; notably model-agnostic across frontier providers.

OpenAI's built-in agent mode that absorbed Operator and Deep Research: a cloud virtual computer with browser, terminal, and connectors that researches, fills forms, and edits files, pausing for user approval on consequential actions and handing back control for logins/payments.

Anthropic's non-technical desktop agent built on the Claude Code harness (no terminal required) that works over local folders, browsers (Claude in Chrome), and full computer use, with MCP connectors, Agent Skills, and plugins — expanded to web and mobile in July 2026 with cloud-run sessions for Max subscribers.