Add optional oh-my-opencode-slim multi-agent orchestration support

Integrate oh-my-opencode-slim as an opt-in feature via INSTALL_OMOS build arg.
A single build arg installs Bun, tmux, and the plugin; runtime activation is
controlled by ENABLE_OMOS and related env vars in the entrypoint.

README.md

@@ -34,6 +34,7 @@ docker compose run --rm devbox
 - **MCP server support** — Node.js included for `npx`-based MCP servers
 - **Non-root user** — runs as `developer` with UID auto-matched to workspace owner (sudo available)
 - **Optional runtimes** — Python, Go via build args (Node.js always included — required for opencode v1.x)
+- **Multi-agent orchestration** — optional [oh-my-opencode-slim](https://github.com/alvinunreal/oh-my-opencode-slim) integration via build arg
 - **AWS CLI v2** — built-in SSO/Bedrock authentication with headless device-code flow
 - **Multi-arch** — amd64 and arm64
 
@@ -102,6 +103,10 @@ docker compose exec -u developer devbox aws --version
 | `SSH_KEY_PATH` | Host SSH key directory | `~/.ssh` |
 | `USER_UID` | Override container user UID | Auto-detect from `/workspace` |
 | `USER_GID` | Override container user GID | Auto-detect from `/workspace` |
+| `ENABLE_OMOS` | Enable oh-my-opencode-slim multi-agent orchestration | `false` |
+| `OMOS_TMUX` | Enable tmux pane integration for OMOS | `false` |
+| `OMOS_SKILLS` | Install OMOS recommended skills on first run | `true` |
+| `OMOS_RESET` | Force regenerate OMOS config on next start | `false` |
 
 ### Custom opencode config
 
@@ -148,6 +153,66 @@ docker compose build --build-arg OPENCODE_VERSION=1.5.0
 |---|---|---|
 | `INSTALL_PYTHON` | `false` | Python 3 + pip + venv |
 | `INSTALL_GO` | `false` | Go toolchain |
+| `INSTALL_OMOS` | `false` | [oh-my-opencode-slim](https://github.com/alvinunreal/oh-my-opencode-slim) multi-agent orchestration (installs Bun, tmux, and plugin) |
+| `OMOS_VERSION` | `latest` | Pin a specific oh-my-opencode-slim version |
+
+## oh-my-opencode-slim (Multi-Agent Orchestration)
+
+[oh-my-opencode-slim](https://github.com/alvinunreal/oh-my-opencode-slim) adds a multi-agent layer on top of opencode — an Orchestrator delegates tasks to specialized agents (Explorer, Oracle, Librarian, Designer, Fixer), each configurable with different models and providers.
+
+### Setup
+
+**1. Build the image with OMOS support:**
+
+```bash
+docker compose build --build-arg INSTALL_OMOS=true
+```
+
+This installs Bun, tmux, and the oh-my-opencode-slim package into the image.
+
+**2. Enable in `.env`:**
+
+```bash
+ENABLE_OMOS=true
+```
+
+**3. Run as normal:**
+
+```bash
+docker compose run --rm devbox
+```
+
+On first start, the entrypoint runs the oh-my-opencode-slim installer in non-interactive mode. It generates agent configuration at `~/.config/opencode/oh-my-opencode-slim.json` inside the container. The default preset uses OpenAI models — edit the generated config or mount your own to customize.
+
+### OMOS Environment Variables
+
+| Variable | Default | Description |
+|---|---|---|
+| `ENABLE_OMOS` | `false` | Activate oh-my-opencode-slim on container start |
+| `OMOS_TMUX` | `false` | Enable tmux pane integration (tmux is included with `INSTALL_OMOS`) |
+| `OMOS_SKILLS` | `true` | Install recommended skills (simplify, agent-browser, cartography) |
+| `OMOS_RESET` | `false` | Force regenerate config on next start (backs up existing config) |
+
+### Custom Configuration
+
+You can mount your own oh-my-opencode-slim config instead of using the auto-generated one:
+
+```yaml
+volumes:
+  - ./oh-my-opencode-slim.json:/home/developer/.config/opencode/oh-my-opencode-slim.json:ro
+```
+
+The config file controls which models power each agent, fallback chains, council setup, and more. See the [oh-my-opencode-slim configuration docs](https://github.com/alvinunreal/oh-my-opencode-slim/blob/master/docs/configuration.md) for the full reference.
+
+### Verifying Agents
+
+After starting opencode with OMOS enabled, run inside the opencode session:
+
+```
+ping all agents
+```
+
+All six agents should respond if your provider authentication is working.
 
 ## AWS Bedrock Authentication
 
@@ -236,9 +301,12 @@ Host Machine
 
 Container (Debian bookworm)
 ├── opencode binary
+├── oh-my-opencode-slim (optional — multi-agent orchestration plugin, includes Bun + tmux)
 ├── AWS CLI v2 (SSO + Bedrock auth)
 ├── git, ssh, ripgrep, fd, jq, curl, fzf
 ├── Node.js (for MCP servers)
+├── Bun (optional — included with oh-my-opencode-slim)
+├── tmux (optional — included with oh-my-opencode-slim)
 ├── entrypoint.sh (UID adjustment, git config, provider setup)
 └── /workspace ← your code lives here
 ```
@@ -252,6 +320,7 @@ Container (Debian bookworm)
 | `/home/developer/.aws` | Host bind mount (if configured) | ✅ Yes | AWS credentials/SSO cache |
 | `/home/developer/.local/share/opencode` | Named volume `devbox-data` | ✅ Yes | Session history, memory |
 | `/home/developer/.config/opencode/opencode.json` | Generated by entrypoint | ❌ No | Provider/model config |
+| `/home/developer/.config/opencode/oh-my-opencode-slim.json` | Generated by entrypoint (if OMOS enabled) | ❌ No | Agent/model mappings |
 
 **opencode config** (`opencode.json`) is auto-generated from `OPENCODE_PROVIDER` on each start. It sets provider and model only — no MCP servers. To use MCP servers or custom settings, mount your own config file (see Custom opencode config above).