feat: import

AGENTS.md

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+# AGENTS.md
+
+## Project overview
+
+This repository builds and publishes a Docker image for [OpenCode](https://opencode.ai), the open source AI coding agent. The image runs OpenCode in headless server mode (`opencode serve`) and is automatically rebuilt and pushed to Docker Hub (`jcabillot/opencode`) every night by a Jenkins pipeline.
+
+## Repository structure
+
+```
+.
+├── Dockerfile      # Image definition
+├── Jenkinsfile     # CI/CD pipeline (nightly build + Docker Hub push)
+└── README.md       # Usage documentation
+```
+
+## Dockerfile conventions
+
+- **Base image**: `node:24-alpine` — use the latest Node.js LTS Alpine image.
+- **Install**: `npm i -g opencode-ai` — installs OpenCode globally.
+- **Version check**: `RUN opencode --version` after install to validate the build and record the installed version in build logs.
+- **Dedicated user**: a non-root `opencode` user and group are created with `addgroup`/`adduser`. All runtime steps run as this user.
+- **Entrypoint**: `["opencode", "serve"]` — the container always starts the HTTP server.
+
+## Jenkinsfile conventions
+
+- The pipeline runs on a `@midnight` cron trigger for nightly rebuilds.
+- Build uses `--no-cache --pull` to always fetch the latest base image and package version.
+- Docker Hub credentials are stored under the `dockerhub_jcabillot` Jenkins credential ID.
+- The image is published as `jcabillot/opencode` (no explicit tag = `latest`).
+
+## Useful commands
+
+```bash
+# Build the image locally
+docker build -t opencode .
+
+# Run the server on all interfaces
+docker run -it -p 4096:4096 opencode --hostname 0.0.0.0
+
+# Run with a project mounted
+docker run -it -p 4096:4096 \
+  -v $(pwd):/home/opencode/project \
+  opencode --hostname 0.0.0.0
+
+# Protect with a password
+docker run -it -p 4096:4096 \
+  -e OPENCODE_SERVER_PASSWORD=secret \
+  opencode --hostname 0.0.0.0
+```
+
+## opencode serve options
+
+| Flag | Default | Description |
+|------|---------|-------------|
+| `--port` | `4096` | Port to listen on |
+| `--hostname` | `127.0.0.1` | Hostname to bind |
+| `--mdns` | `false` | Enable mDNS discovery |
+| `--cors` | `[]` | Additional allowed browser origins |
+
+## Environment variables
+
+| Variable | Description |
+|----------|-------------|
+| `OPENCODE_SERVER_PASSWORD` | Enables HTTP basic auth |
+| `OPENCODE_SERVER_USERNAME` | Overrides the default username (`opencode`) |