Configuration

config.yaml reference, environment overrides, provider routing, and the ~/.phi workspace layout.

phi reads ~/.phi/config.yaml (standard YAML). Environment variables override it for one-off runs. phi config opens an HTML editor for the same file in your browser.

phi config editor

# ~/.phi/config.yaml
models:
  - name: gpt-4o            # model name; "claude-*" routes to the Anthropic API
    api_key: sk-...         # or set PHI_API_KEY
    base_url: https://api.openai.com/v1   # default; PHI_BASE_URL overrides
    context_window: 128000  # optional
    default: true           # the model used at startup; first entry wins if absent
  - name: claude-sonnet-4-20250514   # extra models; switchable at runtime
    api_key: sk-ant-...
    base_url: https://api.anthropic.com
    context_window: 200000

skill_path: ~/.phi/skills # where SKILL.md files are loaded from

agents:
  enabled: true           # default; set false to disable agent_* sub-agent tools

permissions:
  mode: interactive       # interactive | readonly | autopilot | headless-strict
  bash:
    default: ask          # ask | allow | deny
    allow:
      - "go test ./..."
    deny:
      - "rm -rf *"

Environment overrides

Variable	Overrides
`PHI_API_KEY`	`models[].api_key` (default model)
`PHI_MODEL`	`models[].name` (default model)
`PHI_BASE_URL`	`models[].base_url` (default model)
`PHI_SKILL_PATH`	`skill_path`

Provider routing: a base URL containing anthropic or a model name starting with claude uses the Anthropic Messages API; everything else uses the OpenAI-compatible /chat/completions path.

Recommended model: DeepSeek Flash

phi + DeepSeek Flash — the best pairing: grounded, low hallucination, cache hit rates near 100%.

Measured data — 39 LLM rounds, same session: prompt 16k→40k, hit rate 95–100% (avg 98.7%).

Round	Prompt tokens	Cached tokens	Cache hit
1	16,176	15,872	98.1%
10	20,163	20,096	99.7%
20	27,604	26,624	96.4%
30	35,245	35,072	99.5%
39	39,794	39,552	99.4%

Workspace layout

~/.phi/
├── config.yaml   # global configuration
├── bin/          # downloaded search tools (fd, ripgrep)
├── skills/       # SKILL.md skill directories
├── extensions/   # *.go yaegi extension files
├── jobs/         # sub-agent job artifacts (meta, logs, result.md)
└── session/      # persisted sessions, one dir per working directory
    └── <encoded-cwd>/