Struct MutableSession 

pub struct MutableSession { /* private fields */ }

Available on crate feature runner only.

MutableSession wraps a session with shared mutable state.

This mirrors ADK-Go’s MutableSession pattern where state changes from events are immediately visible to all agents sharing the same context. This is critical for SequentialAgent/LoopAgent patterns where downstream agents need to read state set by upstream agents via output_key.

Implementations

impl MutableSession

pub fn new(session: Arc<dyn Session>) -> MutableSession

Create a new MutableSession from a session snapshot. The state is copied from the session and becomes mutable.

pub fn apply_state_delta(&self, delta: &HashMap<String, Value>)

Apply state delta from an event to the mutable state. This is called by the Runner when events are yielded.

pub fn append_event(&self, event: Event)

Append an event to the session’s event list. This keeps the in-memory view consistent.

pub fn events_snapshot(&self) -> Vec<Event>

Get a snapshot of all events in the session. Used by the runner for compaction decisions.

pub fn replace_events(&self, new_events: Vec<Event>)

Replace all events with a new list (used by intra-invocation compaction).

pub fn events_len(&self) -> usize

Return the number of accumulated events without cloning the full list.

pub fn conversation_history_for_agent_impl( &self, agent_name: Option<&str>, branch: &str, ) -> Vec<Content>

Build conversation history, optionally filtered for a specific agent.

When agent_name is Some, events authored by other agents (not “user”, not the named agent, and not function/tool responses) are excluded. This prevents a transferred sub-agent from seeing the parent’s tool calls mapped as “model” role, which would cause the LLM to think work is already done.

When agent_name is None, all events are included (backward-compatible).

branch additionally scopes history to a conversation branch: an event is kept when its branch equals branch or is an ancestor of it, so concurrent ParallelAgent branches do not read each other’s output. An empty branch, or an event without one, matches everything.

Trait Implementations

impl Session for MutableSession

fn id(&self) -> &str

Returns the session identifier.

fn app_name(&self) -> &str

Returns the application name this session belongs to.

fn user_id(&self) -> &str

Returns the user identifier for this session.

fn state(&self) -> &dyn State

Returns the mutable state associated with this session.

fn conversation_history(&self) -> Vec<Content>

Returns the conversation history from this session as Content items

fn conversation_history_for_agent(&self, agent_name: &str) -> Vec<Content>

Returns conversation history filtered for a specific agent.

fn conversation_history_scoped( &self, agent_name: Option<&str>, branch: &str, ) -> Vec<Content>

Returns conversation history scoped to an agent and a conversation branch.

fn append_to_history(&self, _content: Content)

Append content to conversation history (for sequential agent support)

fn try_app_name(&self) -> Result<AppName, AdkError>

Returns the application name as a typed AppName.

fn try_user_id(&self) -> Result<UserId, AdkError>

Returns the user identifier as a typed UserId.

fn try_session_id(&self) -> Result<SessionId, AdkError>

Returns the session identifier as a typed SessionId.

fn try_identity(&self) -> Result<AdkIdentity, AdkError>

Returns the stable session-scoped AdkIdentity triple.

impl State for MutableSession

fn get(&self, key: &str) -> Option<Value>

Returns the value for the given key, or None if not present.

fn set(&mut self, key: String, value: Value)

Set a state value. Implementations should call validate_state_key and reject invalid keys (e.g., by logging a warning or panicking).

fn all(&self) -> HashMap<String, Value>

Returns all key-value pairs in the state.