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H A R N E S S // v1
Chat with Claude. Watch your site rebuild itself in the next pane.
The harness is a local chat-driven IDE for a single website. Point it at a directory, type what you want changed, and a Claude agent edits the files in place while a live preview iframe refreshes next to the chat. SQLite keeps every conversation so you can pick up where you left off.
- A local web app: chat pane on the left, live site preview on the right.
- A Claude agent wired to your site directory with file read/write/edit tools.
- Persistent chat history per site (SQLite, single file on disk).
- Hot-reload preview — saves trigger an iframe refresh, no manual reload.
- The whole source. Read it, audit it, modify it for your own use.
git clone https://github.com/PromptishOperations/harness.git
cd harness
npm install
cp .env.example .env # then edit .env, drop in your API key + site path
npm startOpen http://localhost:7878. Start typing.
| Requirement | Why |
|---|---|
| Node.js 20+ | Runtime for the harness server. |
| Anthropic API key | The agent talks to Claude. Get one at console.anthropic.com. |
| Claude Code CLI | The harness shells out to it for agent execution. |
| A site directory | Static or framework-based. The agent edits files in this dir. |
All config via .env in the project root.
| Variable | Default | Notes |
|---|---|---|
PORT |
7878 |
Where the harness listens. |
SITE_PATH |
(required) | Absolute path to the site directory you're editing. |
DB_PATH |
./data/harness.db |
SQLite file. Created on first run. |
ANTHROPIC_API_KEY |
(required) | Your key. Never commit this. |
MODEL |
claude-sonnet-4-5 |
Override to test other models. |
- Single site per harness instance.
- Chat history persisted across restarts.
- File edit / create / read tools available to the agent.
- Live preview via iframe with auto-refresh on file change.
- Image attachments in chat (drop a screenshot, ask "match this").
- Multi-site switching. One harness, one site. Multi-site lands in v2.
- Hosted/cloud version. This is self-hosted only.
- Auth / multi-user. Run it on your own machine.
- Update mechanism. $99 buys the current state at purchase. No update commitment yet.
- Plugins, themes, integrations.
Source-available. Free for personal use, evaluation, and non-commercial work. Commercial use (any business operation, agency client work, internal company use) requires a $99 commercial license at https://promptish.io/harness.
Honor system. We don't phone home. We do read GitHub stars and issues.
Full terms: LICENSE.
GitHub Issues only: https://github.com/PromptishOperations/harness/issues
No SLA. Best effort. We read everything that gets filed. If you need contracted support, that's a different conversation — operator@promptish.io.
Demo video: coming soon. See DEMO-SCRIPT.md for the walkthrough.
https://promptish.io/harness — $99 one-time, commercial license.
Built by Promptish. We use this internally to ship our own client work.