Struct SessionState 

pub struct SessionState {
    pub id: String,
    pub created_at: String,
    pub title: Option<String>,
    pub runtime: Arc<Mutex<AgentRuntime>>,
    pub plan_approval_gate: Arc<PlanApprovalGate>,
    pub interrupt_token: Arc<Mutex<Option<CancellationToken>>>,
}

Internal session state (not directly serialized to clients).

The AgentRuntime owns the transcript; this struct adds HTTP-layer metadata (id, created_at) and the broadcast channel for SSE clients.

Fields

id: String

created_at: String

title: Option<String>

Optional human-readable title, settable via PATCH /sessions/:id.

runtime: Arc<Mutex<AgentRuntime>>

Runtime is wrapped in a per-session Mutex so concurrent HTTP requests for the same session are serialized without blocking the global lock.

plan_approval_gate: Arc<PlanApprovalGate>

Shared gate for plan-mode approval. Stored here so HTTP handlers can approve/reject without taking the runtime Mutex (which may be held by a running agent turn).

interrupt_token: Arc<Mutex<Option<CancellationToken>>>

Goal-170: cancellation token for the currently running agent turn. POST /sessions/:id/interrupt cancels this token, which causes the kernel to exit with FinishReason::Cancelled at the next step boundary. Replaced with a fresh token at the start of every turn.