Contrabass

A project-level orchestrator for AI coding agents Go + Charm stack reimplementation of OpenAI's Symphony (openai/symphony) — manage work, not agents

Contrabass is a terminal-first orchestrator for issue-driven agent runs, with an optional local web dashboard for live visibility.

Current scope

Today Contrabass ships with:

• A Cobra CLI with TUI, headless, and optional embedded web dashboard modes
• A WORKFLOW.md parser with YAML front matter, Liquid prompt rendering, and $ENV_VAR interpolation
• Issue tracker adapters for Linear, GitHub Issues, and a built-in Internal Board (local filesystem, no external service required)
• Agent runners for Codex app-server, OpenCode, oh-my-opencode, OMX (oh-my-codex), and OMC (oh-my-claudecode)
• Git-worktree-based workspace provisioning under workspaces/<issue-id>
• Teams: multi-agent coordination with a local task board, phased pipeline (plan → exec → verify), live TUI team table, and dual worker modes (tmux-based multi-process or goroutine-based in-process)
• An orchestrator with claim/release, timeout detection, stall detection, deterministic retry backoff, and state snapshots
• A Charm v2 terminal UI built with Bubble Tea, Bubbles, and Lip Gloss
• A React dashboard served from the Go binary, with state snapshots and live SSE updates
• Go unit/integration tests, TUI snapshot tests, and dashboard component/hook tests
• A tmux-based multi-process worker mode (default) alongside the in-process goroutine mode, with JSONL event logging, file-based heartbeats, dispatch queue, governance policies, and crash recovery

Requirements

• Go 1.25+
• Bun 1.3+ for the dashboard/landing workspace
• Git (workspace creation uses git worktree)
• tmux (required for the default tmux worker mode in team runs; not needed for goroutine mode)
• A supported agent runtime:
  • codex app-server
  • opencode serve
  • oh-my-opencode
  • omx (oh-my-codex team runtime)
  • omc (oh-my-claudecode team runtime)
• Tracker credentials for the backend you use:
  • Linear: LINEAR_API_KEY
  • GitHub: GITHUB_TOKEN

From a fresh clone, run bun install once before using the JS/landing build and test commands.

Installation

Homebrew (macOS/Linux)

brew install junhoyeo/contrabass/contrabass

Download from GitHub Releases

Pre-built binaries for macOS and Linux (amd64/arm64) are available on the Releases page.

Build from source

git clone https://github.com/junhoyeo/contrabass.git
cd contrabass
bun install
make build

make build first builds packages/dashboard/dist/ and then embeds it into the Go binary.

Note: go install github.com/junhoyeo/contrabass/cmd/contrabass@latest works for the CLI and TUI, but the embedded web dashboard (--port) will be empty because go install does not run the JS build step.

Quick start

Run with the demo workflow

LINEAR_API_KEY=your-linear-token \
./contrabass --config testdata/workflow.demo.md

Run with the embedded web dashboard

LINEAR_API_KEY=your-linear-token \
./contrabass --config testdata/workflow.demo.md --port 8080

Then open http://localhost:8080.

Run headless

LINEAR_API_KEY=your-linear-token \
./contrabass --config testdata/workflow.demo.md --no-tui

CLI flags

--config string      path to WORKFLOW.md file (required)
--dry-run            exit after first poll cycle
--log-file string    log output path (default "contrabass.log")
--log-level string   log level (debug/info/warn/error) (default "info")
--no-tui             headless mode — skip TUI, log events to stdout
--port int           web dashboard port (0 = disabled)

Team subcommand flags

contrabass team run --config workflow.md [flags]

--worker-mode string   override worker mode (goroutine|tmux, default from config)

How Contrabass works

1. Poll the configured tracker for candidate issues.
2. Claim an eligible issue.
3. Create or reuse a git worktree in workspaces/<issue-id>.
4. Render the prompt body from WORKFLOW.md using issue data.
5. Launch the configured agent runner.
6. Stream agent events, track tokens/phases, and publish orchestrator events.
7. Retry failed runs with exponential backoff + deterministic jitter.
8. Mirror state into the TUI and, when enabled, the embedded web dashboard.

Runtime notes

• WORKFLOW.md is watched with fsnotify; on parse errors, Contrabass keeps the last known good config.
• The Codex runner speaks newline-delimited JSON (JSONL) to codex app-server rather than Content-Length framed messages. See docs/codex-protocol.md.
• The web dashboard currently has live metrics, running sessions, and retry queue data. The rate-limit panel exists, but there is not yet a live rate-limit feed behind it.
• The workflow parser already accepts more Symphony-shaped fields than the runtime fully consumes today. For example, workspace, hooks, and some codex settings are parsed, but the current runtime mainly uses tracker selection, timeouts, retry settings, binary paths, and prompt/template fields.

Team worker modes

Teams support two worker modes, configured via team.worker_mode in the workflow file or the --worker-mode CLI flag:

| Mode | Description | Default | |------|-------------|---------| | tmux | Each worker runs in a separate tmux pane with process isolation, cross-process IPC via JSONL events, and file-based heartbeats | Yes | | goroutine | Workers run as goroutines within the contrabass process — lighter weight, no tmux dependency | |

tmux mode (default) provides:

• Process isolation — each agent CLI runs in its own tmux pane
• JSONL event log for cross-process event streaming
• File-based heartbeat monitoring with stale detection
• Dispatch queue with ack tracking and timeout redelivery
• Governance policies with role routing heuristics
• Crash recovery with state diagnosis and automatic cleanup
• Advisory file locking via flock(2) for safe concurrent access

goroutine mode runs all workers in-process using Go's errgroup and sync.Mutex. It requires no external dependencies but shares the process address space.

Team state is persisted as JSON files under .contrabass/state/team/{teamName}/.

Workflow file format

Contrabass reads a Markdown workflow file with YAML front matter followed by the prompt template body.

---
max_concurrency: 3
poll_interval_ms: 2000
max_retry_backoff_ms: 240000
model: openai/gpt-5-codex
project_url: https://linear.app/acme/project/example
agent_timeout_ms: 900000
stall_timeout_ms: 60000
tracker:
  type: linear
agent:
  type: codex
codex:
  binary_path: codex app-server
---
# Workflow Prompt

Issue title: {{ issue.title }}
Issue description: {{ issue.description }}
Issue URL: {{ issue.url }}

Produce code and tests that satisfy the issue requirements.

Template bindings

The current prompt renderer exposes:

• issue.title
• issue.description
• issue.url

Environment-variable interpolation

String values in YAML front matter can reference environment variables using $NAME syntax.

Examples:

• tracker.token: $GITHUB_TOKEN
• opencode.password: $OPENCODE_SERVER_PASSWORD
• omx.binary_path: $OMX_BINARY
• omc.binary_path: $OMC_BINARY

OMC / OMX workflow sections

For team-runtime-backed runners, set agent.type to omx or omc and configure the corresponding section.

agent:
  type: omx
omx:
  binary_path: omx
  team_spec: 2:executor
  poll_interval_ms: 1500
  startup_timeout_ms: 22000
  ralph: true

agent:
  type: omc
omc:
  binary_path: omc
  team_spec: 2:claude
  poll_interval_ms: 1200
  startup_timeout_ms: 21000

Notes:

• binary_path can point to the installed CLI wrapper, for example omx or omc.
• team_spec is passed directly to the team runtime, such as 1:executor, 2:executor, or 2:claude.
• Contrabass writes the rendered task prompt into .contrabass/runner/<runner>/... inside the workspace and instructs the team runtime to execute from that file.
• OMC/OMX team runners generally require the underlying toolchain prerequisites those CLIs expect, especially tmux-based team support.

Team configuration

The team section configures multi-agent coordination:

team:
  max_workers: 5
  max_fix_loops: 3
  claim_lease_seconds: 300
  state_dir: .contrabass/state/team
  execution_mode: team    # team | single | auto
  worker_mode: tmux       # tmux (default) | goroutine

• worker_mode: Controls how agent workers are spawned. tmux (default) uses separate tmux panes with process isolation. goroutine runs workers in-process.
• execution_mode: Controls coordination strategy. team uses the full phased pipeline, single runs one agent at a time, auto selects based on task count.

Example workflow files

• testdata/workflow.demo.md — demo Linear + Codex workflow
• testdata/workflow.github.md — GitHub + OpenCode workflow
• testdata/workflow.ohmyopencode.md — oh-my-opencode workflow
• testdata/workflow.omx.md — OMX workflow
• testdata/workflow.omc.md — OMC workflow
• testdata/workflow.md — realistic Linear fixture

Sup