Managoat

Managoat is the hosted Fountain. Fountain is the open-source engine, and its name is on the CLI, the API, the SDK and this manual. Everything here applies to Managoat unless a page says it is for a self-hosted server.

Runtimes

A runtime is the coding-agent CLI that a sandbox runs. It is one field on an Agent. It decides which provider's credential that agent needs, how skills land on disk, and where Fountain writes the system prompt.

All four

Runtime Provider Transport Multi-provider
claude anthropic ACP No
codex openai ACP No
opencode Any of the three ACP Yes
gemini google ACP, through gemini --acp No

How to choose

Choose the runtime whose provider you hold a key for. That constraint decides it most of the time. Inference credentials belong to one user, who enters them in the app, and Fountain can export keys for exactly three providers. Read Services Fountain uses.

Choose opencode to make one agent definition work across providers. It is the only multi-provider runtime. It takes the canonical provider/model-id string word for word, then reads the prefix to decide which key to export.

All four speak ACP. Gemini was the last one off it, and it joined on 2026-08-22. So editor integration, the permission flow and the shared block format reach every runtime. The choice is about the provider and the CLI rather than about the transport.

The rule that catches people

Fountain stores model as provider/model-id. It validates the provider half, and it does not validate the model id.

The provider must match the runtime. Fountain rejects a mismatch when you save the agent. It holds no credential for the wrong provider, and the sandbox would start with no inference key at all.

Fountain passes the model id to the CLI unchanged. A model that ships after your Fountain version still works, and a typo reaches the CLI and fails there.

Suggested models

The agent form offers these as suggestions. They are not an allowlist.

Provider Suggested
anthropic claude-opus-5, claude-sonnet-5, claude-opus-4-8, claude-opus-4-7, claude-sonnet-4-6, claude-haiku-4-5
openai gpt-5.3-codex, gpt-5.5
google gemini-3.1-pro-preview, gemini-3.7-flash

GET /api/catalog returns this list for each runtime. A client can then render the current set, and it does not hard-code one.

Where skills and prompts land

Each runtime has its own layout on disk. That is why one skill list produces different paths.

Runtime Skills root skills.sh agent System prompt
claude /home/sprite/.claude/skills claude-code ~/.claude/CLAUDE.md
codex /home/sprite/.codex/skills codex ~/.codex/AGENTS.md
opencode /tmp/.config/opencode/skills opencode ~/.config/opencode/AGENTS.md
gemini /tmp/.gemini/skills gemini-cli ~/.gemini/GEMINI.md