---
title: Configuration
summary: Holon configuration files, keys, credentials, environment variables, and diagnostics.
order: 15
---

# Configuration Reference

Holon stores runtime configuration in JSON files under `~/.holon/`:

| File | Purpose |
|------|---------|
| `~/.holon/config.json` | Providers, model defaults, TUI, web, and runtime settings |
| `~/.holon/credentials.json` | Permission-protected credential storage (managed via `config credentials`) |

## Configuration Keys

Use `holon config get/set/unset/list` to read and write keys. Use `holon config schema` to see every available key with its type, default, and description.

### Model & Provider Settings

| Key | Type | Description |
|-----|------|-------------|
| `model.default` | model_ref | Default provider/model, e.g. `"anthropic/claude-sonnet-4-6"` |
| `model.fallbacks` | model_ref_list | Ordered fallback models when the default is unavailable |
| `runtime.disable_provider_fallback` | boolean | Disable provider/model fallback; require deterministic single-provider execution |

```bash
# Set the default model
holon config set model.default "deepseek-anthropic/deepseek-v4-pro"

# Add fallback models (JSON array)
holon config set model.fallbacks '["anthropic/claude-sonnet-4-6","minimax/MiniMax-M2.7"]'

# Read current default
holon config get model.default

# See all current config
holon config list

# Remove a config key (reverts to default)
holon config unset model.fallbacks
```

### Per-Model Policy

The `models.catalog` key lets you override runtime metadata for specific provider/model refs. Keys under `model.unknown_fallback.*` control policy for models without built-in metadata.

## Credential Management

Credentials are stored securely in `~/.holon/credentials.json`. Use `config credentials` subcommands — **never edit this file directly**.

### Setting Credentials

```bash
# Preferred: use --stdin to avoid shell history leakage
holon config credentials set --kind api_key --stdin deepseek
# Paste your API key and press Enter (Ctrl+D to finish)

# Alternative: --material (visible in shell history — not recommended)
holon config credentials set --kind api_key --material "sk-..." deepseek
```

The `<PROFILE>` argument is a label you choose (e.g. `deepseek`, `bigmodel`, `openai`).

### Listing & Removing

```bash
holon config credentials list
holon config credentials remove deepseek
```

### Environment Variables

As an alternative to the credential store, Holon reads API keys from environment variables:

| Provider | Environment Variable |
|----------|---------------------|
| Anthropic | `ANTHROPIC_AUTH_TOKEN` |
| DeepSeek | `DEEPSEEK_API_KEY` |
| OpenAI | `OPENAI_API_KEY` |
| BigModel (Zhipu) | `BIGMODEL_API_KEY` |
| MiniMax | `MINIMAX_API_KEY` |
| Xiaomi MiMo | `XIAOMI_API_KEY` |
| OpenRouter | `OPENROUTER_API_KEY` |
| Fireworks | `FIREWORKS_API_KEY` |
| Together | `TOGETHER_API_KEY` |
| Mistral | `MISTRAL_API_KEY` |
| xAI | `XAI_API_KEY` |
| Moonshot | `MOONSHOT_API_KEY` |
| Volcengine | `VOLCENGINE_API_KEY` or `ARK_API_KEY` |
| StepFun | `STEPFUN_API_KEY` |
| Qwen | `QWEN_API_KEY` or `DASHSCOPE_API_KEY` |
| HuggingFace | `HUGGINGFACE_API_KEY` or `HF_TOKEN` |
| Venice | `VENICE_API_KEY` |
| Chutes | `CHUTES_API_KEY` |
| NVIDIA | `NVIDIA_API_KEY` |

For a complete, up-to-date list, run `holon config providers list`.

## Provider Configuration

Holon ships with built-in provider definitions for 40+ providers. You can add or override providers in `config.json`.

### Listing Registered Providers

```bash
holon config providers list
```

Each provider entry shows its transport protocol (`anthropic_messages`, `openai_chat_completions`, etc.), base URL, and credential requirement.

### Adding a Custom Provider

```bash
holon config providers set my-proxy \
  --transport openai_chat_completions \
  --base-url "https://my-proxy.example.com/v1" \
  --credential-source env \
  --credential-env "MY_PROXY_API_KEY" \
  --credential-kind api_key
```

Options:
- `--transport`: Protocol — `anthropic_messages`, `openai_chat_completions`, or `openai_responses`
- `--base-url`: API endpoint base URL
- `--credential-source`: `none`, `env`, `credential_profile`, or `external_cli`
- `--credential-kind`: `none`, `api_key`, or `session_token`
- `--credential-env`: Environment variable name (when source is `env`)
- `--credential-profile`: Credential store profile (when source is `credential_profile`)

### Removing a Provider

```bash
holon config providers remove my-proxy
```

## Listing Available Models

```bash
holon config models list
```

This shows each model's availability, credential status, provider, transport, and policy (context window, max output tokens, capabilities).

## Agent-Level Model Overrides

Each agent can override the default model:

```bash
holon agent model set "anthropic/claude-sonnet-4-6" reviewer
```

The override is stored in the agent's own configuration, not the global `model.default`.

## Diagnostics

```bash
# Full system health check including model availability
holon config doctor

# List all configuration keys with types and defaults
holon config schema
```

`config doctor` reports: default model, fallback models, per-model availability, provider settings, and retry policy.

## Configuration File Location

Holon resolves its configuration directory as follows:

1. `$HOLON_HOME/config.json` (if `HOLON_HOME` is set)
2. `~/.holon/config.json` (fallback)

Credentials follow the same pattern with `credentials.json`.

## TUI Settings

| Key | Values | Default | Description |
|-----|--------|---------|-------------|
| `tui.alternate_screen` | `auto`, `always`, `never` | `auto` | Alternate screen buffer behavior |

TUI debug instrumentation is controlled by environment variables:

| Environment variable | Values | Default | Description |
|----------------------|--------|---------|-------------|
| `HOLON_TUI_PRESENTATION_LOG` | `1`, `true`, `yes`, `on`, `debug` | unset | Enable `<HOLON_HOME>/logs/tui/presentation.jsonl` debug logging for stream-driven presentation decisions |
| `HOLON_TUI_PRESENTATION_LOG_MAX_BYTES` | positive integer bytes | `5242880` | Rotate the presentation debug log when it reaches this size |

## Web Fetch/Search Settings

| Key | Type | Default | Description |
|-----|------|---------|-------------|
| `web.fetch.enabled` | boolean | `true` | Enable WebFetch tool |
| `web.fetch.max_chars` | integer | `20000` | Max characters returned to model |
| `web.fetch.max_response_bytes` | integer | `750000` | Max response bytes before truncation |
| `web.fetch.timeout_seconds` | integer | `20` | Per-request timeout |
| `web.fetch.max_redirects` | integer | `5` | Max redirect hops |
| `web.fetch.allowed_hosts` | string_list | `[]` | Hosts allowed (empty = all) |
| `web.fetch.denied_hosts` | string_list | `[]` | Hosts blocked |
| `web.search.enabled` | boolean | `true` | Enable WebSearch tool |
| `web.search.provider` | string | `"auto"` | Default search provider or `auto` |
| `web.search.mode` | enum | `"fallback"` | Routing mode: `single`, `fallback`, or `aggregate` |
| `web.search.providers` | string_list | `[]` | Explicit auto-mode provider attempt order |
| `web.search.max_results` | integer | `5` | Max results returned |
| `web.search.max_provider_attempts` | integer | `3` | Max providers attempted by fallback/aggregate routing |
| `web.providers.<name>.kind` | string | required | Provider kind: `duck_duck_go`, `searxng`, `brave`, `tavily`, `exa`, `perplexity`, `firecrawl`, `open_ai_native`, `anthropic_native`, or `gemini_native` |
| `web.providers.<name>.base_url` | string | unset | Custom provider endpoint |
| `web.providers.<name>.credential_profile` | string | unset | Credential profile for API-backed providers |
| `web.providers.<name>.capabilities` | json_object | derived | Read-only capability metadata surfaced by `holon config get` and routing diagnostics |

## See Also

- [CLI Reference](/reference/cli.md) — Complete CLI command reference
- [Getting Started](/getting-started/first-agent.md) — Step-by-step setup tutorial
