Trait Extension 

pub trait Extension: Send + Sync {
    // Required methods
    fn name(&self) -> &str;
    fn description(&self) -> &str;

    // Provided methods
    fn manifest(&self) -> ExtensionManifest { ... }
    fn register_tools(&self) -> Vec<Arc<dyn AgentTool>> { ... }
    fn register_commands(&self) -> Vec<Command> { ... }
    fn on_load(&self, _ctx: &ExtensionContext) { ... }
    fn on_unload(&self) { ... }
    fn on_message_sent(&self, _msg: &str) { ... }
    fn on_message_received(&self, _msg: &str) { ... }
    fn on_tool_call(&self, _tool: &str, _params: &Value) { ... }
    fn on_tool_result(&self, _tool: &str, _result: &AgentToolResult) { ... }
    fn on_session_start(&self, _session_id: &str) { ... }
    fn on_session_end(&self, _session_id: &str) { ... }
    fn on_settings_changed(&self, _settings: &Settings) { ... }
    fn on_event(&self, _event: &AgentEvent) { ... }
    fn on_before_tool_call(
        &self,
        _tool: &str,
        _args: &Value,
    ) -> Result<(), Error> { ... }
    fn on_after_tool_call(
        &self,
        _tool: &str,
        _result: &AgentToolResult,
    ) -> Result<(), Error> { ... }
    fn on_before_compaction(
        &self,
        _ctx: &CompactionContext,
    ) -> Result<(), Error> { ... }
    fn on_after_compaction(&self, _summary: &str) -> Result<(), Error> { ... }
    fn on_error(&self, _error: &Error) -> Result<(), Error> { ... }
    fn session_before_switch(
        &self,
        _event: &SessionBeforeSwitchEvent,
    ) -> Result<(), Error> { ... }
    fn session_before_fork(
        &self,
        _event: &SessionBeforeForkEvent,
    ) -> Result<(), Error> { ... }
    fn session_before_compact(
        &self,
        _event: &SessionBeforeCompactEvent,
    ) -> Result<(), Error> { ... }
    fn session_compact(&self, _event: &SessionCompactEvent) -> Result<(), Error> { ... }
    fn session_shutdown(&self, _event: &SessionShutdownEvent) { ... }
    fn session_before_tree(
        &self,
        _event: &SessionBeforeTreeEvent,
    ) -> Result<(), Error> { ... }
    fn session_tree(&self, _event: &SessionTreeEvent) { ... }
    fn context(&self, _event: &mut ContextEvent) -> Result<(), Error> { ... }
    fn before_provider_request(
        &self,
        _event: &mut BeforeProviderRequestEvent,
    ) -> Result<(), Error> { ... }
    fn after_provider_response(
        &self,
        _event: &AfterProviderResponseEvent,
    ) -> Result<(), Error> { ... }
    fn model_select(&self, _event: &ModelSelectEvent) { ... }
    fn thinking_level_select(&self, _event: &ThinkingLevelSelectEvent) { ... }
    fn bash(&self, _event: &BashEvent) { ... }
    fn input(&self, _event: &InputEvent) -> InputEventResult { ... }
    fn register_shortcuts(&self) -> Vec<ExtensionShortcut> { ... }
}

Core trait that every oxi extension must implement.

Required Methods

fn name(&self) -> &str

Returns the extension’s unique identifier.

fn description(&self) -> &str

Returns a human-readable description of what this extension does.

Provided Methods

fn manifest(&self) -> ExtensionManifest

Returns the extension manifest containing metadata and permissions. Default implementation constructs a minimal manifest from name() and description().

fn register_tools(&self) -> Vec<Arc<dyn AgentTool>>

Registers custom tools exposed by this extension. Each returned tool becomes available to the agent at runtime. Default returns an empty vector (no custom tools).

fn register_commands(&self) -> Vec<Command>

Registers slash commands exposed by this extension. Each returned command becomes available as /<name> in the input field. Default returns an empty vector (no custom commands).

fn on_load(&self, _ctx: &ExtensionContext)

Called once when the extension is first loaded into a session. Use this to initialize resources, read config, or register with external services.

fn on_unload(&self)

Called once when the extension is unloaded or the session ends. Use this to clean up resources allocated in on_load().

fn on_message_sent(&self, _msg: &str)

Called after the agent sends a message to the LLM. _msg is the raw message content string.

fn on_message_received(&self, _msg: &str)

Called after receiving a response from the LLM. _msg is the raw response content string.

fn on_tool_call(&self, _tool: &str, _params: &Value)

Called immediately before a tool is executed. _tool is the tool name and _params are the JSON arguments.

fn on_tool_result(&self, _tool: &str, _result: &AgentToolResult)

Called immediately after a tool execution completes. _tool is the tool name and _result contains the output or error.

fn on_session_start(&self, _session_id: &str)

Called when a new session starts. _session_id uniquely identifies the session.

fn on_session_end(&self, _session_id: &str)

Called when a session ends. _session_id uniquely identifies the session that ended.

fn on_settings_changed(&self, _settings: &Settings)

Called whenever the user saves or updates settings.

fn on_event(&self, _event: &AgentEvent)

Catch-all hook for any agent event not covered by a specific method.

fn on_before_tool_call(&self, _tool: &str, _args: &Value) -> Result<(), Error>

Called before a tool is executed. Return Err to block the tool call.

fn on_after_tool_call( &self, _tool: &str, _result: &AgentToolResult, ) -> Result<(), Error>

Called after a tool completes. Return Err to surface an error to the agent.

fn on_before_compaction(&self, _ctx: &CompactionContext) -> Result<(), Error>

Called before the context window is compacted. Return Err to abort compaction.

fn on_after_compaction(&self, _summary: &str) -> Result<(), Error>

Called after the context window is compacted with the generated summary.

fn on_error(&self, _error: &Error) -> Result<(), Error>

Called when any error occurs in the agent loop.

fn session_before_switch( &self, _event: &SessionBeforeSwitchEvent, ) -> Result<(), Error>

Called before the active session switches to a different branch or parent.

fn session_before_fork( &self, _event: &SessionBeforeForkEvent, ) -> Result<(), Error>

Called before a session is forked (branched) into a new subtree.

fn session_before_compact( &self, _event: &SessionBeforeCompactEvent, ) -> Result<(), Error>

Called before the context window is compacted.

fn session_compact(&self, _event: &SessionCompactEvent) -> Result<(), Error>

Called when the context window is being compacted.

fn session_shutdown(&self, _event: &SessionShutdownEvent)

Called when a session is shutting down.

fn session_before_tree( &self, _event: &SessionBeforeTreeEvent, ) -> Result<(), Error>

Called before a tree navigation action (branch listing, traversal, etc.).

fn session_tree(&self, _event: &SessionTreeEvent)

Called during a tree navigation action.

fn context(&self, _event: &mut ContextEvent) -> Result<(), Error>

Emits into the agent context. Return Err to signal that the event was handled.

fn before_provider_request( &self, _event: &mut BeforeProviderRequestEvent, ) -> Result<(), Error>

Called before every LLM provider request. Allows the extension to mutate the request parameters (model, temperature, tools, etc.).

fn after_provider_response( &self, _event: &AfterProviderResponseEvent, ) -> Result<(), Error>

Called after every LLM provider response. Allows the extension to read or annotate the response before it is processed by the agent loop.

fn model_select(&self, _event: &ModelSelectEvent)

Called when the user or agent selects a model (via /model or auto-routing).

fn thinking_level_select(&self, _event: &ThinkingLevelSelectEvent)

Called when the thinking level is changed.

fn bash(&self, _event: &BashEvent)

Called when a bash command is about to be executed.

fn input(&self, _event: &InputEvent) -> InputEventResult

Called for every user input keystroke. Return InputEventResult::Handled to suppress the default input handling, or InputEventResult::Transform { text } to replace the input text.

fn register_shortcuts(&self) -> Vec<ExtensionShortcut>

Registers keyboard shortcuts exposed by this extension. Default returns an empty vector (no shortcuts).

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl Extension for NoopExtension