InputAdmission

The first gate of every turn.

InputAdmission is invoked at the start of every turn. It performs three checks in order:

1. Validate — the input is not empty, not too long, and matches the configured schema.
2. Dedup — the input's content fingerprint is not already in flight on the same session.
3. Admit — the input is assigned an InputId and recorded in the per-session admission log.

If any check fails, the run terminates with RunStatus::Rejected and an InputEvent::Rejected is emitted.

The full file is src/runtime/input.rs.

State machine

API

pub struct InputAdmission {
    config: InputAdmissionConfig,
    inflight: Mutex<HashMap<Uuid, InputRecord>>,
}

pub struct InputAdmissionConfig {
    pub max_input_length: usize,          // default: 64 KiB
    pub reject_empty: bool,                // default: true
    pub dedup_window: Duration,            // default: 60s
    pub max_concurrent_per_session: usize, // default: 1
}

impl InputAdmission {
    pub fn new(config: InputAdmissionConfig) -> Self;
    pub async fn admit(&self, session_id: Uuid, content: &str) -> Result<InputId, InputEvent>;
    pub fn complete(&self, id: InputId, result: InputOutcome);
    pub fn reject(&self, id: InputId, reason: &str);
    pub fn inflight(&self) -> Vec<InputRecord>;
}

Dedup

The dedup key is a SHA-256 of the input content, scoped to the session. If the same fingerprint appears within dedup_window, the second admission is rejected with InputEvent::Rejected { reason: "duplicate" }. The window is per-session; a duplicate on a different session is not rejected.

Edge cases

• Empty input — reject_empty: true (default) rejects with InputEvent::Rejected { reason: "empty" }.
• Length limit — max_input_length: 64 * 1024 by default. Inputs over the limit are rejected.
• Concurrent same session — max_concurrent_per_session: 1 (default) blocks the second admission until the first completes.
• Crash mid-admission — the inflight record remains until the session is reaped (default: 5 minutes). The next admission from the same client includes the client_request_id so dedup can recognise the retry.

See also

• AgentRuntime — the caller.
• Turn FSM — the orchestrator.
• SessionGate — the companion that serialises session access.