Struct SessionOptions 

pub struct SessionOptions {

    pub cwd: PathBuf,
    pub model_override: Option<Model>,
    pub model: Option<String>,
    pub provider: Option<String>,
    pub api_key: Option<String>,
    pub thinking: Option<ThinkingLevel>,
    pub mode: Option<AgentMode>,
    pub max_turns: Option<u32>,
    pub max_tokens: Option<u32>,
    pub system_prompt: Option<String>,
    pub no_tools: bool,
    pub session: SessionChoice,
    pub task: Option<TaskContext>,
    pub facts: Vec<Fact>,
    pub lua_loader: Option<LuaToolLoader>,
    pub ui: Option<Arc<dyn UserInterface>>,
    pub auth_path: Option<PathBuf>,
    pub context_prefill: Vec<Message>,
}

Configuration for creating an ImpSession.

All fields have sensible defaults — only cwd is typically required.

Fields

cwd: PathBuf

Working directory. Tools resolve paths relative to this.

model_override: Option<Model>

Prebuilt model override for deterministic tests or embedded callers. When set, ImpSession skips runtime model/provider/auth resolution.

model: Option<String>

Model hint — alias (“sonnet”) or full ID. Resolved against the model registry. Falls back to config, then “sonnet”.

provider: Option<String>

Provider override. Usually auto-detected from the model.

api_key: Option<String>

Runtime API key override (not persisted).

thinking: Option<ThinkingLevel>

Thinking level override.

mode: Option<AgentMode>

Agent mode (full, worker, orchestrator, …).

max_turns: Option<u32>

Maximum turns before the agent stops.

max_tokens: Option<u32>

Max output tokens per response.

system_prompt: Option<String>

Replace the assembled system prompt entirely.

no_tools: bool

Skip native tool registration.

session: SessionChoice

Session persistence strategy.

task: Option<TaskContext>

Task context for headless / unit mode.

facts: Vec<Fact>

Task-specific facts to inject into the system prompt.

lua_loader: Option<LuaToolLoader>

Lua extension loader. Called after native tools are registered. The binary crate typically provides this; library callers can pass None to skip Lua extensions.

ui: Option<Arc<dyn UserInterface>>

Custom UI implementation. Defaults to NullInterface.

auth_path: Option<PathBuf>

Path to auth.json. Defaults to ~/.config/imp/auth.json.

context_prefill: Vec<Message>

Pre-assembled context messages injected before the first prompt. Built by context_prefill::assemble_context() at dispatch time. The agent starts with these files already in its cached prefix.

Trait Implementations

impl Default for SessionOptions

fn default() -> Self

Returns the “default value” for a type.