cogo

A terminal-native agentic CLI for Go developers — like Claude Code, but built in Go on the Google ADK and Gemini 3.x. One static binary, no Python runtime, project-scoped configuration, first-class support for MCP servers and Claude-compatible skills.

📚 Full documentation: go-steer.github.io/cogo

Highlights

• Two modes, one binary. cogo -p "..." for shell pipelines and CI; cogo on a TTY for an interactive Bubble Tea chat with streaming markdown, slash and @-file palettes, and prompt history.
• Project-local configuration. A .agents/ directory holds the model, tool settings, MCP servers, skills, and project memory. Auto-discovered like .git.
• Built-in tools. read_file, write_file, edit_file, list_dir, bash, todo — the same surface a coding agent expects, with per-tool output caps.
• MCP-native. Drop a .agents/mcp.json describing stdio or HTTP MCP servers and their tools become callable. Schema-driven elicitation modal for servers that prompt the user.
• Claude-compatible skills. SKILL.md bundles under .agents/skills/<name>/ are loaded lazily and exposed as agent tools.
• Permissions you can trust. Three modes (ask / allow / yolo), an in-TUI approval modal, a non-overridable bash denylist (no rm -rf /), and path-scope confinement for file tools.
• Project memory. AGENTS.md / CLAUDE.md / GEMINI.md at the project root + ~/.cogo/AGENTS.md user-global, all merged into the system prompt.
• Cost surfacing. Per-turn ↑in · ↓out · $cost footer, running session total in the header, headless one-line summary on stderr.
• Telemetry + transcripts. OpenTelemetry support (--otel=console or OTLP) and an automatically-persisted JSON transcript per session under .agents/sessions/.

Install

Homebrew (recommended):

brew install go-steer/cogo/cogo

Docker / OCI (multi-arch image on GHCR):

docker pull ghcr.io/go-steer/cogo:latest
docker run --rm -it -v "$PWD:/work" -w /work ghcr.io/go-steer/cogo:latest -p "hello"

go install (HEAD from main):

go install github.com/go-steer/cogo/cmd/cogo@latest

Pre-built binaries — every GitHub release attaches a tarball per platform:

Platform	Asset
Linux amd64	cogo_<version>_linux_amd64.tar.gz
Linux arm64	cogo_<version>_linux_arm64.tar.gz
macOS Intel	cogo_<version>_darwin_amd64.tar.gz
macOS Apple Silicon	cogo_<version>_darwin_arm64.tar.gz

A checksums.txt (SHA256) ships in every release. The install docs include an auto-detect installer one-liner and a verification snippet.

Verify after install: cogo --version.

Quick start

Cogo speaks Gemini through one of two auth paths:

# Option A — Vertex AI
gcloud auth application-default login
export GOOGLE_GENAI_USE_VERTEXAI=true
export GOOGLE_CLOUD_PROJECT=your-project
export GOOGLE_CLOUD_LOCATION=us-central1   # or "global"

# Option B — Public Gemini API
export GOOGLE_API_KEY=...

(See .env.example for a copy-pasteable template.)

Then either:

# Interactive TUI
cogo

# One-shot, pipeable
cogo -p "Summarize internal/agent in three bullets."

Want a fresh project bootstrapped? cogo init writes .agents/{config.json, .gitignore, AGENTS.md} with sensible defaults; cogo init --interactive walks a wizard for provider / model / permission mode.

Configuration

Cogo looks for a .agents/ directory by walking up from the current working directory (same way Git finds .git). Layout:

.agents/
├── config.json          # model, provider, permission mode, path scope, OTEL
├── mcp.json             # MCP server definitions (stdio + Streamable HTTP)
├── skills/              # one subdir per skill, each with a SKILL.md
│   └── example/SKILL.md
├── AGENTS.md            # project memory (CLAUDE.md / GEMINI.md also accepted)
├── sessions/            # transcripts, written on /quit and Ctrl+C
└── logs/                # JSONL debug logs (when --debug is set)

When no .agents/ is present Cogo runs with built-in defaults — useful for quick one-offs in arbitrary directories.

Slash commands

Command	Effect
/help	Full keymap + command list.
/memory	Show which memory files were loaded and from where.
/stats	Per-session token + cost breakdown.
/model	Open the model picker, or /model <id> to switch directly.
/mcp	List configured MCP servers + each server's tools.
/skills	List discovered skills.
/reload	Re-read .agents/ from disk and rebuild the agent in place (no chat reset).
/clear	Clear chat history (with confirmation).
/quit	Exit cleanly, persisting a session transcript.

Type / at the start of an empty prompt to open the slash palette; type @ anywhere to inline a file by path.

Permissions

Three modes set in .agents/config.json under permissions.mode:

• ask — prompt before any mutating tool call (default).
• allow — pre-approve the listed tool patterns; prompt for everything else.
• yolo — no prompts. Use sparingly; the bash denylist still blocks the truly dangerous commands.

When the modal appears: y allow once, s allow this session, a always allow (persisted to .agents/config.json), n or Esc deny.

File-touching tools are scoped to the project root + ~/.cogo/ plus any path_scope.allow glob patterns you add. Out-of-scope reads via @<path> still work but surface a one-line warning so private files don't end up in the model context by accident.

MCP + skills

Drop a JSON file at .agents/mcp.json:

{
  "version": 1,
  "servers": {
    "filesystem": {
      "transport": "stdio",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-filesystem", "/Users/me/work"]
    },
    "github": {
      "transport": "http",
      "url": "https://mcp.example.com/v1",
      "headers": { "Authorization": "Bearer ${env:GITHUB_TOKEN}" }
    }
  }
}

Tools are namespaced as <server>_<tool> so they never collide with built-ins. /mcp shows status and tool inventory.

Skills follow Claude Code's bundle layout — drop .agents/skills/<name>/SKILL.md (with frontmatter name: + description:) and the agent will discover and invoke it. Body markdown is loaded on demand.

Telemetry & observability

• OpenTelemetry — set cfg.OTEL.Exporter to none (default), console, or otlp. With otlp, point OTEL_EXPORTER_OTLP_ENDPOINT at your collector. Spans cover the agent loop, tool calls, and provider requests.
• Session transcripts — every interactive session writes .agents/sessions/<timestamp>.json on exit, with the full message log and usage totals.
• Debug logs — cogo --debug -p "..." swaps the slog handler to a JSONL writer under .agents/logs/<timestamp>.jsonl for after-the-fact inspection.

Troubleshooting

VS Code integrated terminal: random characters disappear

If you run cogo inside VS Code's integrated terminal and see characters dropping out of typed input or rendered output — most often the CSI command terminators (D, b, n are the usual suspects, but other letters can vanish too) — you're hitting a known interaction between Bubble Tea's escape sequences and VS Code's WebGL terminal renderer.

The fix is one VS Code setting, not a cogo config:

1. ⌘+, (or Ctrl+,) to open Settings.
2. Search for gpuAcceleration.
3. Change Terminal › Integrated: Gpu Acceleration from auto to canvas.
4. Close and reopen the terminal panel and rerun cogo.

If canvas doesn't fully resolve it, try off. The perf cost in either case is invisible for an interactive TUI like cogo. This isn't cogo-specific — most Bubble Tea TUIs hit the same WebGL renderer bug.

Development

The full local CI pipeline lives under dev/ and is the same source of truth as the GitHub Actions workflow. Quick start:

dev/tools/ci              # run every check (format, vet, build, lint, mod-tidy, tests, vuln)
dev/tools/fix-go-format   # auto-fix formatting

Missing tools (golangci-lint, goimports, govulncheck) auto-install on first use; only prereq is a Go toolchain. See dev/README.md for the full layout, contributor checklist, and license-header rules.

End-to-end Vertex tests are gated on COGO_E2E=1 plus the same auth env vars used by the runtime:

COGO_E2E=1 \
GOOGLE_GENAI_USE_VERTEXAI=true \
GOOGLE_CLOUD_PROJECT=... \
GOOGLE_CLOUD_LOCATION=... \
  go test ./internal/headless/... -run E2E -v

Documentation

• ROADMAP.md — release themes (v0.2.0 → v0.5.0) and links to the GitHub milestones.
• CONTRIBUTING.md — how to file issues, the PR workflow, DCO sign-off, commit conventions.
• CODE_OF_CONDUCT.md — Contributor Covenant v2.1.
• docs/REQUIREMENTS.md — V1 scope, functional & non-functional requirements.
• docs/DESIGN.md — architecture, configuration, module layout, testing strategy.
• AGENTS.md — project memory that cogo itself loads when run inside this repo.

License

Apache 2.0 — see LICENSE.