Module identity 

Core traits and types.

Always available regardless of feature flags. Includes:

• Agent - The fundamental trait for all agents
• Tool / Toolset - For extending agents with capabilities
• Session / State - For managing conversation context
• Event - For streaming agent responses
• AdkError / Result - Unified error handling Typed identity primitives for app, user, session, and invocation. Typed identity primitives for ADK-Rust.

This module provides strongly-typed wrappers for the identity values used throughout the ADK runtime: application names, user identifiers, session identifiers, and invocation identifiers.

Identity Layers

ADK distinguishes three identity concerns:

• Auth identity (RequestContext): who is authenticated and what scopes they hold.
• Session identity (AdkIdentity): the stable (app, user, session) triple that addresses a conversation session.
• Execution identity (ExecutionIdentity): session identity plus the per-invocation invocation_id, branch, and agent_name.

Validation Rules

All leaf identifiers (AppName, UserId, SessionId, InvocationId) enforce the same validation:

• Must not be empty.
• Must not contain null bytes (\0).
• Must not exceed MAX_ID_LEN bytes (512).
• Characters like :, |, /, and @ are allowed — validation does not couple to any backend’s internal key encoding.

Examples

use adk_core::identity::{AdkIdentity, AppName, ExecutionIdentity, InvocationId, SessionId, UserId};

let identity = AdkIdentity::new(
    AppName::try_from("weather-app").unwrap(),
    UserId::try_from("tenant:alice@example.com").unwrap(),
    SessionId::generate(),
);

let exec = ExecutionIdentity {
    adk: identity,
    invocation_id: InvocationId::generate(),
    branch: String::new(),
    agent_name: "planner".to_string(),
};

Structs

AdkIdentity

The stable session-scoped identity triple: application name, user, and session.

AppName

A typed wrapper around the logical application name used in session addressing.

ExecutionIdentity

The per-invocation execution identity, built from a stable AdkIdentity plus invocation-scoped metadata.

InvocationId

A typed wrapper around a single execution or turn identifier.

SessionId

A typed wrapper around a logical session identifier.

UserId

A typed wrapper around a logical user identifier.

Enums

IdentityError

Error returned when a raw string cannot be converted into a typed identifier.

Constants

MAX_ID_LEN

Maximum allowed length for any identity value, in bytes.