loopflow 0.12.11

//! The wave server's HTTP surface — a thin view over in-process state.
//!
//! Every endpoint reads or nudges [`WaveRuntime`]; none of them own logic. The
//! timeline is served as-is, live events stream over SSE, and a POSTed message
//! is journaled and broadcast to the resident's subscription. Discovery is a
//! dumb pointer file, not a transport: `wave/<name>/.wave-endpoint` holds
//! `127.0.0.1:<port>` and nothing else; `.wave-resident-token` beside it holds
//! this boot's resident token (see [`crate::wave::wire`]).
//!
//! This module is VENDOR-FREE: the loop lives in the resident process
//! ([`crate::wave::resident`]), which publishes through the resident door
//! (`/resident/attach`, `/resident/deltas`, `/resident/context` — token-gated)
//! and listens on its own wave's `/events?inbox=true` subscription. The
//! listener holds every pen; the resident holds the vendor.
//!
//! Wire contract (snake_case, stable — a Loopflow worker builds against it):
//! - `GET /health` → `{status, loop_state, wave, turns, paused, uptime_seconds}`;
//!   `status` is listener liveness — always `serving` while this process
//!   answers; `loop_state` is the resident's state (`idle | turning | interrupting
//!   | failed`), or null before any resident has attached; a listener whose resident died reads
//!   `status: "serving", loop_state: "failed"`.
//! - `GET /conversation` → `{turns: [Turn]}`; includes the open turn (status
//!   `running`), if one is in progress, after the finalized thread. Optional
//!   `?limit=N` tails the last N turns (open turn included) — `wave_context`
//!   passes 12; absent means the whole thread.
//! - `GET /events` → SSE, the served mind's thread. Human subscriptions replay
//!   the most recent 12 turns by default; optional `?limit=N` overrides that
//!   tail while every subsequent turn still streams live. Resident inbox
//!   subscriptions remain complete.
//!   Event names:
//!   - `state`: data is the loop-state name (`idle | turning | interrupting |
//!     failed`), sent once on subscribe (before the turn replay) and again on
//!     every transition — the composer keys its verb off it.
//!   - `turn`: data is a `Turn` JSON; the thread replays on connect (including
//!     the open turn), then streams live. Turn ids repeat: an in-progress turn
//!     is re-sent whole as it grows and finalization sends the terminal turn
//!     under the same id — each frame replaces the client's previous state
//!     for that id (upsert, never append-if-seen).
//!   - `inbox` (only with `?inbox=true`, the resident's subscription): data
//!     is an [`InboxFrame`] — a resident-directed human message, typed Task or
//!     Project observation, promotion wake, or control op. The pending queue
//!     (journaled inputs not yet named in any `answers`) replays on
//!     connect, then live ops stream; a bare interrupt rides live-only with
//!     `id: null` (nothing journaled). The default
//!     stream is byte-identical to the pre-resident wire.
//! - The resident door (token-gated via the `x-lf-resident-token` header —
//!   401 without this boot's token):
//!   - `POST /resident/attach {pid}` → `{wave}` — registers the
//!     resident's pid for liveness and revives a `failed` loop (a fresh
//!     resident IS the revival).
//!   - `POST /resident/deltas {deltas: [...]}` → `{accepted}` — ordered turn
//!     deltas, applied to the journal fold
//!     ([`WaveRuntime::apply_resident_delta`]).
//!   - `GET /resident/context` → `{playhead, provider_session}` — the
//!     pre-turn snapshot and optional typed provider thread; serving it drains
//!     pending child observations first.
//! - `POST /messages {id?, op, text}` → `{message, state, epoch}`. `op` is
//!   required — `"message"` (queued; the next turn answers it), `"steer"`
//!   (into the live turn when the harness supports it, else degrades to a
//!   queued message), `"interrupt"` (cancel the open turn; non-empty text
//!   becomes the next turn — "interrupt & send"; while idle, an interrupt is
//!   a no-op success). `text` may be empty only for `interrupt` (400
//!   otherwise). A local epoch journals immediately; a Discord epoch uses
//!   `id` as an enforced provider nonce and returns the source-bearing provider
//!   message, which the adapter then queues from its canonical Discord id.
//!   `message` is null only for a bare interrupt (nothing was said); `state` is the
//!   loop-state name when the request was accepted — ops are applied by the
//!   loop asynchronously, so watch the stream's `state` events for the
//!   outcome.
//! - `POST /observations` optionally accepts a promotion latency nudge, verifies
//!   it against the durable occurrence and registry parentage, drains the same
//!   durable promotion through polling when the request is lost, and journals
//!   it plus authoritative child observations idempotently before waking or
//!   queueing the resident.
//!   Loopback-only internal door; child Work never writes the Wave journal.
//! - `POST /stop` → 202 and requests graceful listener shutdown. The listener
//!   remains the sole owner of resident, registry, and discovery-file cleanup.
//!
//! `Turn` is [`crate::chat::turns::ChatTurn`].

use std::collections::{HashSet, VecDeque};
use std::convert::Infallible;
use std::path::{Path, PathBuf};
use std::sync::{Arc, Mutex};

use axum::extract::{DefaultBodyLimit, Query, State};
use axum::http::{HeaderMap, StatusCode};
use axum::response::sse::{Event, KeepAlive, Sse};
use axum::response::IntoResponse;
use axum::routing::{get, post};
use axum::{Json, Router};
use futures_util::stream::{self, Stream, StreamExt};
use secrecy::{ExposeSecret, SecretString};
use serde::{Deserialize, Serialize};
use subtle::ConstantTimeEq;
use time::OffsetDateTime;
use tokio::sync::{broadcast, watch};
use tokio_stream::wrappers::errors::BroadcastStreamRecvError;
use tokio_stream::wrappers::BroadcastStream;

use crate::chat::turns::ChatTurn;
use crate::wave::chat::{
    ChatBacking, ChatBackingHealth, ChatHistorySnapshot, ChatHistoryState, ChatMessageSource,
    ConversationEpoch, PostMessageErrorResponse, PostMessageResponse, WaveChatMessage,
};
use crate::wave::discord::{DiscordError, DiscordProjection};
use crate::wave::journal::{MessageOp, PendingMessage};
use crate::wave::playhead::PlayheadView;
use crate::wave::registry::{process_alive, ObserverSlot, StoreObserver};
use crate::wave::runtime::{
    ChatWriteError, InboxItem, TurnBroadcast, TurnDeltaFrame, TurnFrame, WaveRuntime,
};
use crate::wave::state::LoopState;
use crate::wave::supervisor::SupervisorHandle;
use crate::wave::wire::{
    AttachRequest, AttachResponse, ContextResponse, InboxFrame, PostDeltasRequest,
    PostDeltasResponse, RESIDENT_TOKEN_FILE, RESIDENT_TOKEN_HEADER,
};

/// Basename of the discovery pointer under `wave/<name>/`.
pub const ENDPOINT_FILE: &str = ".wave-endpoint";

/// The resident door's server-side state: this boot's token and the seat —
/// the attached resident's pid, for liveness probing. Shared with the
/// supervisor ([`crate::wave::supervisor`]), which probes attached pids and
/// clears the seat when the resident dies.
///
/// The token is held as a [`SecretString`] and compared in constant time
/// ([`subtle::ConstantTimeEq`]) — never `==`, never surfaced in `Debug` or a
/// log.
#[derive(Debug, Clone)]
pub struct ResidentDoor {
    token: SecretString,
    seat: Arc<Mutex<Option<u32>>>,
}

impl ResidentDoor {
    pub fn new(token: impl Into<String>) -> Self {
        Self {
            token: SecretString::new(token.into()),
            seat: Arc::new(Mutex::new(None)),
        }
    }

    /// The attached resident's pid, if one has attached and not been cleared.
    pub fn seat_pid(&self) -> Option<u32> {
        *self.seat.lock().expect("resident seat lock poisoned")
    }

    /// Record the resident occupying the seat (attach, or spawn).
    pub fn record_pid(&self, pid: u32) {
        *self.seat.lock().expect("resident seat lock poisoned") = Some(pid);
    }

    /// The resident died: free the seat.
    pub fn clear_seat(&self) {
        *self.seat.lock().expect("resident seat lock poisoned") = None;
    }

    fn authorize(&self, headers: &HeaderMap) -> Result<(), (StatusCode, String)> {
        let presented = headers
            .get(RESIDENT_TOKEN_HEADER)
            .and_then(|value| value.to_str().ok())
            .unwrap_or_default();
        if token_matches(&self.token, presented) {
            return Ok(());
        }
        Err((
            StatusCode::UNAUTHORIZED,
            format!("missing or wrong {RESIDENT_TOKEN_HEADER}"),
        ))
    }
}

/// Constant-time compare of a presented token against a stored secret — the
/// door's only equality check. Length inequality short-circuits; equal-length
/// inputs compare in constant time.
fn token_matches(expected: &SecretString, provided: &str) -> bool {
    expected
        .expose_secret()
        .as_bytes()
        .ct_eq(provided.as_bytes())
        .into()
}

/// A fresh per-boot resident token.
pub fn generate_resident_token() -> String {
    format!(
        "{}{}",
        uuid::Uuid::new_v4().simple(),
        uuid::Uuid::new_v4().simple()
    )
}

/// One-shot lifecycle door for `POST /stop`. The listener owns the receiver;
/// the HTTP surface only requests shutdown, leaving cleanup to `run_listener`.
#[derive(Debug, Clone)]
pub struct ShutdownDoor {
    requested: watch::Sender<bool>,
}

impl ShutdownDoor {
    pub fn new() -> Self {
        let (requested, _) = watch::channel(false);
        Self { requested }
    }

    fn request(&self) {
        self.requested.send_replace(true);
    }

    pub async fn wait(&self) {
        let mut receiver = self.requested.subscribe();
        if *receiver.borrow() {
            return;
        }
        let _ = receiver.changed().await;
    }
}

impl Default for ShutdownDoor {
    fn default() -> Self {
        Self::new()
    }
}

#[derive(Debug, Serialize)]
struct HealthBody {
    /// Listener liveness: always `"serving"` while this process answers. The
    /// resident's condition is `loop_state` — a listener whose resident
    /// died is `status: "serving", loop_state: "failed"`.
    status: String,
    /// Resident loop state name, or null for a listener with no resident
    /// (before any resident attaches).
    loop_state: Option<String>,
    wave: String,
    turns: usize,
    /// Whether the wave is paused (GOAL.md `paused: true`): the listener
    /// refuses to start turns while set, though it keeps serving and queueing.
    paused: bool,
    uptime_seconds: i64,
    active_epoch: ConversationEpoch,
    chat_backing_health: ChatBackingHealth,
}

/// `GET /conversation` query. `limit` is explicitly Optional: `None` serves
/// the whole thread, `Some(n)` tails the last n turns.
#[derive(Debug, Deserialize)]
struct ConversationQuery {
    limit: Option<usize>,
    epoch: Option<String>,
}

/// `POST /messages` request body. `op` is required — explicit, never inferred.
/// `id` becomes the Discord nonce when the active epoch is provider-backed.
#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
struct PostMessage {
    id: Option<String>,
    op: MessageOp,
    text: String,
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
struct ObservationRequest {
    promotion: Option<PromotionRequest>,
}

#[derive(Debug, Deserialize)]
#[serde(deny_unknown_fields)]
struct PromotionRequest {
    parent: String,
}

/// `GET /events` query. `inbox` is explicitly Optional: `true` adds the
/// resident's `inbox` frames (pending replay + live ops) to the subscription;
/// absent/false leaves the wire byte-identical to the pre-resident stream.
/// `limit` bounds only the initial turn replay; live turns are never dropped.
#[derive(Debug, Deserialize)]
struct EventsQuery {
    inbox: Option<bool>,
    limit: Option<usize>,
}

pub(crate) const HUMAN_THREAD_REPLAY_LIMIT: usize = 12;

/// Server state: the runtime, the resident door, the shared observer slot (for the
/// context door's freshness poll), the supervisor handle (to signal an
/// attach), and when the server started (for uptime).
#[derive(Clone)]
struct ServerState {
    runtime: Arc<WaveRuntime>,
    resident: ResidentDoor,
    observer: Arc<ObserverSlot>,
    supervisor: Option<SupervisorHandle>,
    shutdown: ShutdownDoor,
    discord: Option<DiscordProjection>,
    run_attach: Option<WaveRunAttach>,
    started_at: OffsetDateTime,
}

#[derive(Debug, Clone)]
pub(crate) struct WaveRunAttach {
    pub store: crate::store::SharedStore,
    pub lease: crate::durable::RunLease,
    pub cwd: PathBuf,
}

/// Request-body ceiling for the wave routes. Loopback + token gate this, but
/// an unbounded body is a needless same-user allocation.
const MAX_BODY_BYTES: usize = 1_048_576;

/// Build the router over a running [`WaveRuntime`].
///
/// `observer` seeds the late-installable store poller. `GET /resident/context`
/// freshens it before serving. `supervisor` lets the attach door stand the
/// respawn ladder down (`None` in tests without a supervisor).
pub fn router(
    runtime: Arc<WaveRuntime>,
    resident: ResidentDoor,
    observer: Option<Arc<StoreObserver>>,
    supervisor: Option<SupervisorHandle>,
    shutdown: ShutdownDoor,
) -> Router {
    let observer = Arc::new(ObserverSlot::new(runtime.clone(), observer));
    router_with_observer(runtime, resident, observer, supervisor, shutdown)
}

pub(crate) fn router_with_observer(
    runtime: Arc<WaveRuntime>,
    resident: ResidentDoor,
    observer: Arc<ObserverSlot>,
    supervisor: Option<SupervisorHandle>,
    shutdown: ShutdownDoor,
) -> Router {
    router_with_chat_projection(
        runtime, resident, observer, supervisor, shutdown, None, None,
    )
}

pub(crate) fn router_with_chat_projection(
    runtime: Arc<WaveRuntime>,
    resident: ResidentDoor,
    observer: Arc<ObserverSlot>,
    supervisor: Option<SupervisorHandle>,
    shutdown: ShutdownDoor,
    discord: Option<DiscordProjection>,
    run_attach: Option<WaveRunAttach>,
) -> Router {
    let state = ServerState {
        runtime,
        resident,
        observer,
        supervisor,
        shutdown,
        discord,
        run_attach,
        started_at: OffsetDateTime::now_utc(),
    };
    Router::new()
        .route("/health", get(health_handler))
        .route("/stop", post(stop_handler))
        .route("/conversation", get(conversation_handler))
        .route("/playhead", get(playhead_handler))
        .route("/events", get(events_handler))
        .route("/messages", post(messages_handler))
        .route("/observations", post(observations_handler))
        .route("/resident/attach", post(resident_attach_handler))
        .route("/resident/deltas", post(resident_deltas_handler))
        .route("/resident/context", get(resident_context_handler))
        .layer(DefaultBodyLimit::max(MAX_BODY_BYTES))
        .with_state(state)
}

async fn observations_handler(
    State(state): State<ServerState>,
    request: Option<Json<ObservationRequest>>,
) -> Result<StatusCode, (StatusCode, String)> {
    let observer = state.observer.acquire().await.ok_or_else(|| {
        (
            StatusCode::SERVICE_UNAVAILABLE,
            "child observations require the shared Loopflow registry".to_string(),
        )
    })?;
    if let Some(promotion) = request.and_then(|Json(request)| request.promotion) {
        observer
            .deliver_promotion(&promotion.parent)
            .await
            .map_err(|error| {
                (
                    StatusCode::CONFLICT,
                    format!("promotion wake does not match registry truth: {error}"),
                )
            })?;
    }
    observer.poll_once().await;
    Ok(StatusCode::NO_CONTENT)
}

async fn stop_handler(State(state): State<ServerState>) -> StatusCode {
    state.shutdown.request();
    StatusCode::ACCEPTED
}

async fn playhead_handler(
    State(state): State<ServerState>,
) -> Result<Json<PlayheadView>, (StatusCode, String)> {
    state
        .runtime
        .ensure_playhead()
        .map(Json)
        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err.to_string()))
}

async fn health_handler(State(state): State<ServerState>) -> Json<HealthBody> {
    // `loop_state` is null until a resident has ever been spawned or attached —
    // A listener with no resident has no Loop to report on.
    let loop_state = state
        .runtime
        .resident_expected()
        .then(|| state.runtime.loop_state().name().to_string());
    let active_epoch = state.runtime.active_conversation_epoch();
    let chat_backing_health = if matches!(active_epoch.backing, ChatBacking::Local) {
        ChatBackingHealth::Ready
    } else if let Some(discord) = &state.discord {
        discord.health()
    } else {
        ChatBackingHealth::Blocked {
            detail: "Discord projection is not available on this listener".to_string(),
        }
    };
    Json(HealthBody {
        status: "serving".to_string(),
        loop_state,
        wave: state.runtime.name().to_string(),
        turns: state.runtime.thread_len(),
        paused: state.runtime.paused(),
        uptime_seconds: (OffsetDateTime::now_utc() - state.started_at).whole_seconds(),
        active_epoch,
        chat_backing_health,
    })
}

// -- The resident door (token-gated; see crate::wave::wire) --

async fn resident_attach_handler(
    State(state): State<ServerState>,
    headers: HeaderMap,
    Json(body): Json<AttachRequest>,
) -> Result<Json<AttachResponse>, (StatusCode, String)> {
    state.resident.authorize(&headers)?;
    // Seat exclusivity: one loop per wave. A live seat already probed alive
    // refuses the attach naming it — a second resident would split-brain the
    // wire. A dead/absent seat is free (takeover after a crash rides the same
    // door; the supervisor's own seat probe frees a dead pid on its cadence).
    // `--force` is `lf wave`'s boot flag, not the door's business.
    if let Some(seated) = state.resident.seat_pid() {
        if seated != body.pid && process_alive(seated).await {
            return Err((
                StatusCode::CONFLICT,
                format!(
                    "wave '{}' already has a live resident on the seat (pid {seated}); \
                     stop it before attaching, or use `lf wave <name> --force` to take over",
                    state.runtime.name()
                ),
            ));
        }
    }
    if let Some(run_attach) = &state.run_attach {
        let process_group =
            crate::engine::process::process_group_id(body.pid).ok_or_else(|| {
                (
                    StatusCode::CONFLICT,
                    format!("resident pid {} has no isolated process group", body.pid),
                )
            })?;
        let run = run_attach
            .store
            .current_run(&run_attach.lease.work)
            .await
            .map_err(|error| (StatusCode::INTERNAL_SERVER_ERROR, error.to_string()))?
            .ok_or_else(|| {
                (
                    StatusCode::CONFLICT,
                    "Wave Run authority disappeared before resident attach".to_string(),
                )
            })?;
        if run.state == crate::durable::RunState::Reserved {
            run_attach
                .store
                .advance_run(
                    &run_attach.lease,
                    crate::durable::RunAdvance::RunStarting {
                        containment: crate::durable::Containment::ProcessGroup {
                            id: i64::from(process_group),
                        },
                        cwd: run_attach.cwd.clone(),
                    },
                )
                .await
                .map_err(|error| (StatusCode::INTERNAL_SERVER_ERROR, error.to_string()))?;
        }
    }
    state.resident.record_pid(body.pid);
    state.runtime.set_resident_expected();
    // Tell the keeper: an attached resident stands the respawn ladder down
    // (the fresh resident IS the revival) and is watched by pid probe.
    if let Some(supervisor) = &state.supervisor {
        supervisor.on_attach(body.pid);
    }
    // A fresh resident IS the revival: a failed loop goes idle on attach.
    if matches!(state.runtime.loop_state(), LoopState::Failed { .. }) {
        state
            .runtime
            .transition(LoopState::Idle, "resident attached");
    }
    state
        .runtime
        .ensure_playhead()
        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err.to_string()))?;
    tracing::info!(pid = body.pid, "resident attached");
    Ok(Json(AttachResponse {
        wave: state.runtime.name().to_string(),
    }))
}

async fn resident_deltas_handler(
    State(state): State<ServerState>,
    headers: HeaderMap,
    Json(body): Json<PostDeltasRequest>,
) -> Result<Json<PostDeltasResponse>, (StatusCode, String)> {
    state.resident.authorize(&headers)?;
    let accepted = body.deltas.len() as u64;
    for delta in body.deltas {
        state.runtime.apply_resident_delta(delta);
    }
    Ok(Json(PostDeltasResponse { accepted }))
}

async fn resident_context_handler(
    State(state): State<ServerState>,
    headers: HeaderMap,
) -> Result<Json<ContextResponse>, (StatusCode, String)> {
    state.resident.authorize(&headers)?;
    // Drain child observations before the resident captures its next turn.
    state.observer.poll_once().await;
    let playhead = state
        .runtime
        .ensure_playhead()
        .map_err(|err| (StatusCode::INTERNAL_SERVER_ERROR, err.to_string()))?;
    Ok(Json(ContextResponse {
        playhead,
        provider_session: state.runtime.latest_provider_session(),
    }))
}

async fn conversation_handler(
    State(state): State<ServerState>,
    Query(query): Query<ConversationQuery>,
) -> Result<Json<ChatHistorySnapshot>, (StatusCode, String)> {
    if query.limit == Some(0) {
        return Err((StatusCode::BAD_REQUEST, "limit must be at least 1".into()));
    }
    // The tail is taken inside the runtime lock: a `?limit=N` request clones
    // only the N turns it serves, not the whole thread.
    let active_epoch = state.runtime.active_conversation_epoch();
    let epochs = state.runtime.conversation_epochs();
    let selected_epoch = match query.epoch.as_deref() {
        Some(id) => epochs
            .iter()
            .find(|epoch| epoch.id == id)
            .cloned()
            .ok_or_else(|| (StatusCode::NOT_FOUND, format!("unknown chat epoch '{id}'")))?,
        None => active_epoch.clone(),
    };
    let fetch_limit = query.limit.map(|limit| limit.saturating_add(1));
    let (state_value, detail, mut messages) = match &selected_epoch.backing {
        ChatBacking::Local => (
            ChatHistoryState::Available,
            None,
            state
                .runtime
                .chat_messages(Some(&selected_epoch.id), fetch_limit),
        ),
        ChatBacking::Discord { .. }
            if state
                .runtime
                .is_imported_conversation_epoch(&selected_epoch.id) =>
        {
            (
                ChatHistoryState::Unavailable,
                Some(
                    "Legacy Discord history has no safe provider boundary; open the channel in Discord"
                        .to_string(),
                ),
                Vec::new(),
            )
        }
        ChatBacking::Discord { .. } => match &state.discord {
            Some(discord) => match discord
                .history(&state.runtime, &selected_epoch, fetch_limit)
                .await
            {
                Ok(messages) => (ChatHistoryState::Available, None, messages),
                Err(error) => (
                    ChatHistoryState::Unavailable,
                    Some(error.to_string()),
                    Vec::new(),
                ),
            },
            None => (
                ChatHistoryState::Unavailable,
                Some("Discord history requires the active Wave listener".to_string()),
                Vec::new(),
            ),
        },
    };
    let truncated = query.limit.is_some_and(|limit| messages.len() > limit);
    messages = tail_wave_messages(messages, query.limit);
    Ok(Json(ChatHistorySnapshot {
        epochs,
        selected_epoch_id: Some(selected_epoch.id),
        state: state_value,
        detail,
        messages,
        truncated,
    }))
}

/// The door is opaque on resident ops: this handler validates SHAPE only —
/// `text` may be empty only for
/// `interrupt` — then hands the op to the runtime uninterpreted
/// ([`WaveRuntime::try_deliver`]). What steer or interrupt *means* lives with the
/// resident, not the ear. Honest partial: the `{turn, state}` echo still
/// leaks that a bare interrupt appends nothing (`turn: null`), but that fact
/// comes back from the runtime's return, not from the door interpreting.
async fn messages_handler(
    State(state): State<ServerState>,
    Json(body): Json<PostMessage>,
) -> axum::response::Response {
    if body.text.trim().is_empty() && !matches!(body.op, MessageOp::Interrupt) {
        return (
            StatusCode::BAD_REQUEST,
            Json(PostMessageErrorResponse {
                error: "text is required for every op but interrupt".to_string(),
                epoch: state.runtime.active_conversation_epoch(),
            }),
        )
            .into_response();
    }
    let active_epoch = state.runtime.active_conversation_epoch();
    if !body.text.trim().is_empty() && matches!(active_epoch.backing, ChatBacking::Discord { .. }) {
        if let Some(discord) = &state.discord {
            let request_id = body
                .id
                .as_deref()
                .filter(|id| !id.trim().is_empty())
                .map(str::to_string)
                .unwrap_or_else(|| uuid::Uuid::new_v4().to_string());
            return match discord
                .post_authored(&state.runtime, body.op, body.text.trim(), &request_id)
                .await
            {
                Ok(message) => Json(PostMessageResponse {
                    message: Some(message),
                    state: state.runtime.loop_state().name().to_string(),
                    epoch: active_epoch,
                })
                .into_response(),
                Err(error) => {
                    let status = if matches!(error, DiscordError::MessageTooLong { .. }) {
                        StatusCode::BAD_REQUEST
                    } else {
                        StatusCode::BAD_GATEWAY
                    };
                    (
                        status,
                        Json(PostMessageErrorResponse {
                            error: format!("message was not accepted: {error}"),
                            epoch: active_epoch,
                        }),
                    )
                        .into_response()
                }
            };
        }
    }
    let turn = match state.runtime.try_deliver_authored(body.op, body.text) {
        Ok(turn) => turn,
        Err(error) => {
            let status = match &error {
                ChatWriteError::OpenDiscord => StatusCode::CONFLICT,
                ChatWriteError::Journal(_) => StatusCode::INTERNAL_SERVER_ERROR,
            };
            return (
                status,
                Json(PostMessageErrorResponse {
                    error: format!("message was not accepted: {error}"),
                    epoch: state.runtime.active_conversation_epoch(),
                }),
            )
                .into_response();
        }
    };
    let message = turn.map(|turn| state.runtime.committed_local_message(turn));
    Json(PostMessageResponse {
        message,
        state: state.runtime.loop_state().name().to_string(),
        epoch: state.runtime.active_conversation_epoch(),
    })
    .into_response()
}

/// The served mind's thread as SSE. Human subscriptions open with epoch and
/// backing health, then carry source-bearing `message` frames and plain
/// `message-delta` increments. Resident inbox subscriptions keep the private
/// `turn`/`turn-delta` wire. Both emit `resync` when a turn broadcast lags so
/// the client reconnects for a fresh atomic snapshot. Snapshot and
/// subscription are atomic in the runtime (broadcasts share the append lock),
/// so no live frame is older than the replayed snapshot.
///
/// There is no secondary routing scope inside a Wave listener.
async fn events_handler(
    State(state): State<ServerState>,
    Query(query): Query<EventsQuery>,
) -> axum::response::Response {
    let shutdown = state.shutdown.clone();
    let include_inbox = query.inbox == Some(true);
    let replay_limit = if include_inbox {
        query.limit
    } else {
        Some(query.limit.unwrap_or(HUMAN_THREAD_REPLAY_LIMIT))
    };
    let sub = state.runtime.subscribe_with_snapshot(replay_limit);
    let epoch = sub.epoch.clone();
    let (discord_replay, discord_seen, backing_health) =
        if !include_inbox && matches!(epoch.backing, ChatBacking::Discord { .. }) {
            match &state.discord {
                Some(discord) => {
                    let fetch_limit = replay_limit.unwrap_or(HUMAN_THREAD_REPLAY_LIMIT).max(100);
                    match discord
                        .history(&state.runtime, &epoch, Some(fetch_limit))
                        .await
                    {
                        Ok(messages) => {
                            let seen = discord_message_ids(&messages);
                            let replay = tail_wave_messages(messages, replay_limit)
                                .into_iter()
                                .map(|message| Ok(wave_message_event(&message)))
                                .collect();
                            (replay, seen, discord.health())
                        }
                        Err(error) => {
                            let health = match discord.health() {
                                blocked @ ChatBackingHealth::Blocked { .. } => blocked,
                                _ => ChatBackingHealth::Retrying {
                                    detail: error.to_string(),
                                },
                            };
                            (Vec::new(), HashSet::new(), health)
                        }
                    }
                }
                None => (
                    Vec::new(),
                    HashSet::new(),
                    ChatBackingHealth::Blocked {
                        detail: "Discord history requires the active Wave listener".to_string(),
                    },
                ),
            }
        } else {
            (Vec::new(), HashSet::new(), ChatBackingHealth::Ready)
        };
    // The resident's subscription replays the pending queue after the
    // thread — its boot inbox. Consumption is validated at the resident
    // door, so a stale replay can never double-consume.
    let inbox_replay: Vec<Result<Event, Infallible>> = if include_inbox {
        sub.pending
            .iter()
            .map(|message| {
                let frame = if let Some(observation) = sub.tasks.get(&message.id) {
                    InboxFrame::Task {
                        observation: observation.clone(),
                    }
                } else if let Some(observation) = sub.projects.get(&message.id) {
                    InboxFrame::Project {
                        observation: observation.clone(),
                    }
                } else if let Some(wake) = sub.promotions.get(&message.id) {
                    InboxFrame::Promotion {
                        parent_wave_id: wake.parent_wave_id.clone(),
                        parent: wake.parent.clone(),
                    }
                } else {
                    pending_inbox_frame(message)
                };
                Ok(inbox_event(&frame))
            })
            .collect()
    } else {
        Vec::new()
    };
    let turn_replay: Vec<Result<Event, Infallible>> = if include_inbox {
        sub.turns
            .into_iter()
            .map(|turn| Ok(turn_event(&turn)))
            .collect()
    } else if matches!(epoch.backing, ChatBacking::Local) {
        sub.turns
            .into_iter()
            .filter_map(|turn| local_message_event(&epoch, turn).map(Ok))
            .collect()
    } else {
        discord_replay
    };
    let epoch_replay = (!include_inbox)
        .then(|| Ok(conversation_epoch_event(&epoch)))
        .into_iter();
    let replay = stream::iter(
        epoch_replay
            .chain((!include_inbox).then(|| Ok(backing_health_event(&backing_health))))
            .chain(std::iter::once(Ok(state_event(&sub.state))))
            .chain(sub.playhead.into_iter().map(|p| Ok(playhead_event(&p))))
            .chain(turn_replay)
            .chain(inbox_replay),
    );
    // The resident keeps private turn frames; human chat converts the same
    // broadcasts into source-bearing messages. Both make lag an explicit
    // `resync`, never a silent drop.
    let live_turns: BoxedEventStream = if include_inbox {
        Box::pin(turn_event_stream(sub.turn_rx))
    } else if matches!(epoch.backing, ChatBacking::Local) {
        Box::pin(chat_message_event_stream(sub.turn_rx, epoch))
    } else if let Some(discord) = state.discord.clone() {
        Box::pin(discord_message_event_stream(
            discord,
            state.runtime.clone(),
            epoch,
            discord_seen,
            backing_health,
        ))
    } else {
        Box::pin(stream::empty())
    };
    // Lagged: fine — the next transition carries the current state.
    let live_states = live_stream(sub.state_rx, |s| state_event(&s));
    let live_playhead = live_stream(sub.playhead_rx, |p| playhead_event(&p));
    let mut live: BoxedEventStream = Box::pin(stream::select(
        live_turns,
        stream::select(live_states, live_playhead),
    ));
    if include_inbox {
        // Lagged: the pending fold is the durable queue; a resident that
        // falls behind resubscribes.
        let live_inbox = live_stream(sub.inbox_rx, |item| inbox_event(&inbox_item_frame(&item)));
        live = Box::pin(stream::select(live, live_inbox));
    }
    // Axum's graceful shutdown waits for open responses. End this long-lived
    // response when /stop fires so the listener can finish before asking the
    // resident to leave; otherwise each side waits for the other forever.
    let merged: BoxedEventStream = Box::pin(replay.chain(live).take_until(async move {
        shutdown.wait().await;
    }));
    axum::response::IntoResponse::into_response(Sse::new(merged).keep_alive(KeepAlive::default()))
}

type BoxedEventStream =
    std::pin::Pin<Box<dyn Stream<Item = Result<Event, Infallible>> + Send + 'static>>;

/// One live SSE stream off a broadcast receiver: each value becomes an event,
/// a lagged receiver drops silently (every stream's durable state resyncs on
/// reconnect — see each call site for what backs it).
fn live_stream<T, F>(
    rx: broadcast::Receiver<T>,
    to_event: F,
) -> impl Stream<Item = Result<Event, Infallible>> + Send + 'static
where
    T: Clone + Send + 'static,
    F: Fn(T) -> Event + Send + 'static,
{
    BroadcastStream::new(rx).filter_map(move |res| {
        let out = res.ok().map(|value| Ok(to_event(value)));
        async move { out }
    })
}

/// The live turn substream: whole turns as `turn` frames (replace-by-id),
/// in-turn increments as `turn-delta` frames (absorb-by-id). Unlike the other
/// live streams this one must NOT silently drop on lag: a client grows its open
/// turn from deltas, so a swallowed increment leaves its reconstruction
/// permanently short a fragment — a silently corrupt transcript. Instead a lag
/// emits an explicit `resync` frame and ends the substream; the client
/// reconnects to `/events` for a fresh atomic snapshot
/// ([`WaveRuntime::subscribe_with_snapshot`]), the only resync with no
/// snapshot-vs-stream cursor race. Whole frames at turn open and finalize
/// re-baseline the reconstruction for free between resyncs.
fn turn_event_stream(
    rx: broadcast::Receiver<TurnBroadcast>,
) -> impl Stream<Item = Result<Event, Infallible>> + Send + 'static {
    stream::unfold(Some(BroadcastStream::new(rx)), |state| async move {
        let mut inner = state?;
        let recv = inner.next().await?;
        match turn_wire_frame(recv) {
            TurnWireFrame::Whole(frame) => Some((
                Ok(Event::default().event("turn").data(frame.json.as_str())),
                Some(inner),
            )),
            TurnWireFrame::Delta(frame) => Some((
                Ok(Event::default()
                    .event("turn-delta")
                    .data(frame.json.as_str())),
                Some(inner),
            )),
            // Lag: signal an explicit resync, then end the substream (state
            // `None`) so the next poll returns nothing and the client reconnects.
            TurnWireFrame::Resync => {
                Some((Ok(Event::default().event("resync").data("reconnect")), None))
            }
        }
    })
}

fn chat_message_event_stream(
    rx: broadcast::Receiver<TurnBroadcast>,
    epoch: ConversationEpoch,
) -> impl Stream<Item = Result<Event, Infallible>> + Send + 'static {
    stream::unfold(Some(BroadcastStream::new(rx)), move |state| {
        let epoch = epoch.clone();
        async move {
            let mut inner = state?;
            loop {
                let recv = inner.next().await?;
                match recv {
                    Ok(TurnBroadcast::Whole(frame)) => {
                        if let Some(event) = local_message_event(&epoch, frame.turn.clone()) {
                            return Some((Ok(event), Some(inner)));
                        }
                    }
                    Ok(TurnBroadcast::Delta(frame)) => {
                        let Some(journal_seq) = turn_id_seq(&frame.delta.turn_id) else {
                            continue;
                        };
                        if journal_seq <= epoch.journal_seq {
                            continue;
                        }
                        return Some((
                            Ok(Event::default().event("message-delta").data(
                                serde_json::to_string(&frame.delta)
                                    .expect("TurnDelta serializes to JSON"),
                            )),
                            Some(inner),
                        ));
                    }
                    Err(BroadcastStreamRecvError::Lagged(_)) => {
                        return Some((
                            Ok(Event::default().event("resync").data("reconnect")),
                            None,
                        ));
                    }
                }
            }
        }
    })
}

struct DiscordMessageStreamState {
    projection: DiscordProjection,
    runtime: Arc<WaveRuntime>,
    epoch: ConversationEpoch,
    seen: HashSet<String>,
    pending: VecDeque<WaveChatMessage>,
    health: ChatBackingHealth,
}

fn discord_message_event_stream(
    projection: DiscordProjection,
    runtime: Arc<WaveRuntime>,
    epoch: ConversationEpoch,
    seen: HashSet<String>,
    health: ChatBackingHealth,
) -> impl Stream<Item = Result<Event, Infallible>> + Send + 'static {
    let state = DiscordMessageStreamState {
        projection,
        runtime,
        epoch,
        seen,
        pending: VecDeque::new(),
        health,
    };
    stream::unfold(state, |mut state| async move {
        loop {
            if let Some(message) = state.pending.pop_front() {
                return Some((Ok(wave_message_event(&message)), state));
            }
            let provider_health = state.projection.health();
            if provider_health != state.health {
                state.health = provider_health;
                return Some((Ok(backing_health_event(&state.health)), state));
            }
            tokio::time::sleep(std::time::Duration::from_secs(2)).await;
            match state
                .projection
                .history(&state.runtime, &state.epoch, Some(100))
                .await
            {
                Ok(messages) => {
                    for message in messages {
                        let Some(id) = discord_message_id(&message) else {
                            continue;
                        };
                        if state.seen.insert(id.to_string()) {
                            state.pending.push_back(message);
                        }
                    }
                }
                Err(error) => {
                    let health = match state.projection.health() {
                        blocked @ ChatBackingHealth::Blocked { .. } => blocked,
                        _ => ChatBackingHealth::Retrying {
                            detail: error.to_string(),
                        },
                    };
                    if health != state.health {
                        state.health = health;
                        return Some((Ok(backing_health_event(&state.health)), state));
                    }
                }
            }
        }
    })
}

/// One turn broadcast poll resolved to what it becomes on the wire. A lag is
/// `Resync`, NEVER a silently dropped frame — that distinction is the whole
/// point of this substream, so it is pinned by a unit test.
enum TurnWireFrame {
    Whole(Arc<TurnFrame>),
    Delta(Arc<TurnDeltaFrame>),
    Resync,
}

fn turn_wire_frame(recv: Result<TurnBroadcast, BroadcastStreamRecvError>) -> TurnWireFrame {
    match recv {
        Ok(TurnBroadcast::Whole(frame)) => TurnWireFrame::Whole(frame),
        Ok(TurnBroadcast::Delta(frame)) => TurnWireFrame::Delta(frame),
        Err(BroadcastStreamRecvError::Lagged(_)) => TurnWireFrame::Resync,
    }
}

fn turn_event(turn: &ChatTurn) -> Event {
    Event::default()
        .event("turn")
        .data(serde_json::to_string(turn).expect("ChatTurn serializes to JSON"))
}

fn conversation_epoch_event(epoch: &ConversationEpoch) -> Event {
    Event::default()
        .event("epoch")
        .data(serde_json::to_string(epoch).expect("ConversationEpoch serializes to JSON"))
}

fn backing_health_event(health: &ChatBackingHealth) -> Event {
    Event::default()
        .event("backing-health")
        .data(serde_json::to_string(health).expect("ChatBackingHealth serializes to JSON"))
}

fn wave_message_event(message: &WaveChatMessage) -> Event {
    Event::default()
        .event("message")
        .data(serde_json::to_string(message).expect("WaveChatMessage serializes to JSON"))
}

fn discord_message_ids(messages: &[WaveChatMessage]) -> HashSet<String> {
    messages
        .iter()
        .filter_map(discord_message_id)
        .map(str::to_string)
        .collect()
}

fn discord_message_id(message: &WaveChatMessage) -> Option<&str> {
    match &message.source {
        ChatMessageSource::Discord { message_id, .. } => Some(message_id),
        ChatMessageSource::Local { .. } => None,
    }
}

fn tail_wave_messages(
    messages: Vec<WaveChatMessage>,
    limit: Option<usize>,
) -> Vec<WaveChatMessage> {
    let take = limit.unwrap_or(messages.len()).min(messages.len());
    messages[messages.len() - take..].to_vec()
}

fn local_message_event(epoch: &ConversationEpoch, turn: ChatTurn) -> Option<Event> {
    let journal_seq = turn_id_seq(&turn.id)?;
    if journal_seq <= epoch.journal_seq {
        return None;
    }
    let message = WaveChatMessage {
        epoch_id: epoch.id.clone(),
        source: ChatMessageSource::Local { journal_seq },
        turn,
    };
    Some(
        Event::default()
            .event("message")
            .data(serde_json::to_string(&message).expect("WaveChatMessage serializes to JSON")),
    )
}

fn turn_id_seq(turn_id: &str) -> Option<u64> {
    turn_id.strip_prefix("turn-")?.parse().ok()
}

fn playhead_event(playhead: &PlayheadView) -> Event {
    Event::default()
        .event("playhead")
        .data(serde_json::to_string(playhead).expect("PlayheadView serializes to JSON"))
}

fn state_event(state: &LoopState) -> Event {
    Event::default().event("state").data(state.name())
}

fn inbox_event(frame: &InboxFrame) -> Event {
    Event::default()
        .event("inbox")
        .data(serde_json::to_string(frame).expect("InboxFrame serializes to JSON"))
}

fn pending_inbox_frame(message: &PendingMessage) -> InboxFrame {
    InboxFrame::Message {
        id: message.id.0.clone(),
        op: message.op,
        text: message.text.clone(),
        source: message.source.clone(),
    }
}

fn inbox_item_frame(item: &InboxItem) -> InboxFrame {
    match item {
        InboxItem::Message(message) => pending_inbox_frame(message),
        InboxItem::Task(observation) => InboxFrame::Task {
            observation: observation.clone(),
        },
        InboxItem::Project(observation) => InboxFrame::Project {
            observation: observation.clone(),
        },
        InboxItem::Promotion {
            parent_wave_id,
            parent,
        } => InboxFrame::Promotion {
            parent_wave_id: parent_wave_id.clone(),
            parent: parent.clone(),
        },
        InboxItem::Interrupt => InboxFrame::Interrupt,
        InboxItem::Skip => InboxFrame::Skip,
    }
}

/// Path to the discovery pointer for a wave.
pub fn endpoint_path(repo_root: &Path, wave: &str) -> PathBuf {
    repo_root.join("wave").join(wave).join(ENDPOINT_FILE)
}

/// How long the boot-time probe waits for an existing endpoint to answer.
const ENDPOINT_PROBE_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(2);

/// Probe an existing discovery pointer: `Some(addr)` when a live wave server
/// for `wave` answers `GET /health` at the recorded address. This is the
/// file-level one-brain floor — it works with no registry store at all
/// (observed live: a second unregistered server overwrote the pointer and,
/// on shutdown, deleted it, leaving the first server undiscoverable). A
/// missing/unreadable file, a dead address, or an answer for a different
/// wave is a stale pointer — `None`, safe to overwrite.
pub async fn live_endpoint(repo_root: &Path, wave: &str) -> Option<String> {
    let addr = std::fs::read_to_string(endpoint_path(repo_root, wave)).ok()?;
    let addr = addr.trim().to_string();
    if addr.is_empty() {
        return None;
    }
    let client = reqwest::Client::builder()
        .timeout(ENDPOINT_PROBE_TIMEOUT)
        .build()
        .ok()?;
    let body: serde_json::Value = client
        .get(format!("http://{addr}/health"))
        .send()
        .await
        .ok()?
        .json()
        .await
        .ok()?;
    (body.get("wave").and_then(serde_json::Value::as_str) == Some(wave)).then_some(addr)
}

/// Publish the loopback endpoint so Loopflow can find the server. Writes ONLY
/// `127.0.0.1:<port>` — a pointer, never message content.
pub fn write_endpoint(
    repo_root: &Path,
    wave: &str,
    addr: std::net::SocketAddr,
) -> std::io::Result<()> {
    let path = endpoint_path(repo_root, wave);
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    std::fs::write(path, addr.to_string())
}

/// Remove the discovery pointer on shutdown — only when it still holds this
/// server's own address. A takeover that overwrote the file owns it now;
/// deleting it here would leave that live server undiscoverable. Best-effort.
pub fn remove_endpoint(repo_root: &Path, wave: &str, own_addr: &str) {
    let path = endpoint_path(repo_root, wave);
    match std::fs::read_to_string(&path) {
        Ok(contents) if contents.trim() == own_addr => {
            let _ = std::fs::remove_file(path);
        }
        _ => {}
    }
}

/// Path to the resident-token file for a wave (beside `.wave-endpoint`).
pub fn resident_token_path(repo_root: &Path, wave: &str) -> PathBuf {
    repo_root.join("wave").join(wave).join(RESIDENT_TOKEN_FILE)
}

/// Publish this boot's resident token so the internal resident can present it
/// — the same filesystem-trust domain as
/// the endpoint pointer. Owner-only on unix.
pub fn write_resident_token(repo_root: &Path, wave: &str, token: &str) -> std::io::Result<()> {
    let path = resident_token_path(repo_root, wave);
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    std::fs::write(&path, token)?;
    #[cfg(unix)]
    {
        use std::os::unix::fs::PermissionsExt;
        std::fs::set_permissions(&path, std::fs::Permissions::from_mode(0o600))?;
    }
    Ok(())
}

/// Read the current resident token for attachment.
pub fn read_resident_token(repo_root: &Path, wave: &str) -> Option<String> {
    let token = std::fs::read_to_string(resident_token_path(repo_root, wave)).ok()?;
    let token = token.trim().to_string();
    (!token.is_empty()).then_some(token)
}

/// Remove the token file on shutdown — only while it still holds this boot's
/// token (a takeover owns the file now). Best-effort.
pub fn remove_resident_token(repo_root: &Path, wave: &str, own_token: &str) {
    let path = resident_token_path(repo_root, wave);
    match std::fs::read_to_string(&path) {
        Ok(contents) if contents.trim() == own_token => {
            let _ = std::fs::remove_file(path);
        }
        _ => {}
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::chat::turns::ChatTurn;
    use crate::id::WaveId;
    use crate::store::{open_store, SharedStore};
    use crate::wave::journal::{journal_path, read_events, EventKind, JournalAppendStage};
    use crate::wave::Wave;

    fn whole_broadcast(id: &str) -> TurnBroadcast {
        let turn = ChatTurn::user(id.to_string(), "hi".to_string());
        let json = serde_json::to_string(&turn).expect("serialize");
        TurnBroadcast::Whole(Arc::new(TurnFrame { turn, json }))
    }

    #[test]
    fn post_message_response_fixture_round_trips() {
        let fixture = include_str!(concat!(
            env!("CARGO_MANIFEST_DIR"),
            "/../../tests/fixtures/dto/post_message_response.json"
        ));
        let response: PostMessageResponse =
            serde_json::from_str(fixture).expect("decode post message response fixture");
        let encoded = serde_json::to_string(&response).expect("encode post message response");
        let decoded: PostMessageResponse =
            serde_json::from_str(&encoded).expect("re-decode post message response");
        assert_eq!(decoded, response);
    }

    #[test]
    fn post_message_error_response_fixture_round_trips() {
        let fixture = include_str!(concat!(
            env!("CARGO_MANIFEST_DIR"),
            "/../../tests/fixtures/dto/post_message_error_response.json"
        ));
        let response: PostMessageErrorResponse =
            serde_json::from_str(fixture).expect("decode post message error fixture");
        let encoded = serde_json::to_string(&response).expect("encode post message error");
        let decoded: PostMessageErrorResponse =
            serde_json::from_str(&encoded).expect("re-decode post message error");
        assert_eq!(decoded, response);
    }

    #[test]
    fn a_lagged_turn_broadcast_maps_to_resync_not_a_dropped_frame() {
        // The distinction this substream exists for: a lag becomes an explicit
        // resync, never a silently swallowed increment.
        assert!(matches!(
            turn_wire_frame(Err(BroadcastStreamRecvError::Lagged(3))),
            TurnWireFrame::Resync
        ));
        assert!(matches!(
            turn_wire_frame(Ok(whole_broadcast("turn-1"))),
            TurnWireFrame::Whole(_)
        ));
    }

    #[tokio::test]
    async fn turn_stream_signals_one_resync_then_ends_on_lag() {
        // A capacity-2 channel overfilled before any read: the receiver lags.
        let (tx, rx) = broadcast::channel::<TurnBroadcast>(2);
        for i in 0..8 {
            let _ = tx.send(whole_broadcast(&format!("turn-{i}")));
        }
        drop(tx);

        let mut stream = Box::pin(turn_event_stream(rx));
        // Exactly one frame — the resync — then the substream ends. A silent
        // drop would surface the retained tail instead of telling the client to
        // reconnect; ending is what forces the fresh atomic snapshot.
        assert!(
            stream.next().await.is_some(),
            "a lagged turn stream signals resync, not silence"
        );
        assert!(
            stream.next().await.is_none(),
            "the substream ends after resync so the client reconnects"
        );
    }

    #[test]
    fn write_and_remove_endpoint_roundtrips() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let addr: std::net::SocketAddr = "127.0.0.1:54321".parse().unwrap();
        write_endpoint(tmp.path(), "ship", addr).expect("write endpoint");

        let path = endpoint_path(tmp.path(), "ship");
        assert_eq!(std::fs::read_to_string(&path).unwrap(), "127.0.0.1:54321");

        remove_endpoint(tmp.path(), "ship", "127.0.0.1:54321");
        assert!(!path.exists());
    }

    /// A server taken over by `--force` must not delete the pointer the new
    /// server wrote: remove only what still holds our own address.
    #[test]
    fn remove_endpoint_leaves_a_foreign_pointer_untouched() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let addr: std::net::SocketAddr = "127.0.0.1:50000".parse().unwrap();
        write_endpoint(tmp.path(), "ship", addr).expect("write endpoint");

        remove_endpoint(tmp.path(), "ship", "127.0.0.1:50001");
        let path = endpoint_path(tmp.path(), "ship");
        assert_eq!(
            std::fs::read_to_string(&path).unwrap(),
            "127.0.0.1:50000",
            "foreign pointer survives our shutdown"
        );
    }

    /// The token file round-trips and removal honors ownership, like the
    /// endpoint pointer.
    #[test]
    fn resident_token_file_roundtrips_and_respects_ownership() {
        let tmp = tempfile::tempdir().expect("tempdir");
        assert!(read_resident_token(tmp.path(), "ship").is_none());
        write_resident_token(tmp.path(), "ship", "tok-1").expect("write");
        assert_eq!(
            read_resident_token(tmp.path(), "ship").as_deref(),
            Some("tok-1")
        );

        // A foreign token (takeover) survives our shutdown; our own doesn't.
        remove_resident_token(tmp.path(), "ship", "tok-other");
        assert_eq!(
            read_resident_token(tmp.path(), "ship").as_deref(),
            Some("tok-1")
        );
        remove_resident_token(tmp.path(), "ship", "tok-1");
        assert!(read_resident_token(tmp.path(), "ship").is_none());
    }

    #[tokio::test]
    async fn stop_route_requests_listener_shutdown() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let runtime = WaveRuntime::open("ship".into(), tmp.path().to_path_buf()).expect("open");
        let shutdown = ShutdownDoor::new();
        let requested = shutdown.clone();
        let observer = Arc::new(ObserverSlot::new(runtime.clone(), None));
        let app = router_with_observer(
            runtime,
            ResidentDoor::new("resident"),
            observer,
            None,
            shutdown,
        );
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let addr = listener.local_addr().unwrap();
        let server = tokio::spawn(async move {
            axum::serve(listener, app).await.ok();
        });

        let response = reqwest::Client::new()
            .post(format!("http://{addr}/stop"))
            .send()
            .await
            .unwrap();
        assert_eq!(response.status(), reqwest::StatusCode::ACCEPTED);
        requested.wait().await;
        server.abort();
    }

    #[tokio::test]
    async fn message_write_failures_are_not_accepted_and_can_be_retried() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let runtime = WaveRuntime::open("ship".into(), tmp.path().to_path_buf()).expect("open");
        let app = router_with_observer(
            runtime.clone(),
            ResidentDoor::new("resident"),
            Arc::new(ObserverSlot::new(runtime.clone(), None)),
            None,
            ShutdownDoor::new(),
        );
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
            .await
            .expect("bind");
        let addr = listener.local_addr().expect("address");
        let server = tokio::spawn(async move {
            axum::serve(listener, app).await.ok();
        });
        let client = reqwest::Client::new();
        let url = format!("http://{addr}/messages");
        let body = serde_json::json!({"op": "message", "text": "keep this"});
        let mut turn_rx = runtime.subscribe_turns();
        let mut inbox_rx = runtime.subscribe_inbox();

        for failure in [JournalAppendStage::Write, JournalAppendStage::Flush] {
            runtime.fail_next_journal_append(failure);
            let response = client
                .post(&url)
                .json(&body)
                .send()
                .await
                .expect("failed append response");
            assert_eq!(response.status(), StatusCode::INTERNAL_SERVER_ERROR);
            assert!(response
                .text()
                .await
                .expect("error body")
                .contains("message was not accepted"));
            assert!(runtime.thread_snapshot().is_empty());
            assert!(runtime.pending_messages().is_empty());
            assert_eq!(
                read_events(&journal_path(tmp.path(), "ship")).len(),
                1,
                "only the epoch boundary exists"
            );
            assert!(matches!(
                turn_rx.try_recv(),
                Err(broadcast::error::TryRecvError::Empty)
            ));
            assert!(matches!(
                inbox_rx.try_recv(),
                Err(broadcast::error::TryRecvError::Empty)
            ));
        }

        let response = client
            .post(&url)
            .json(&body)
            .send()
            .await
            .expect("retry response");
        assert_eq!(response.status(), StatusCode::OK);
        let accepted: serde_json::Value = response.json().await.expect("accepted body");
        assert_eq!(accepted["message"]["turn"]["id"], "turn-2");
        assert_eq!(accepted["message"]["turn"]["role"], "user");
        assert_eq!(accepted["message"]["turn"]["text"], "keep this");
        assert_eq!(accepted["message"]["source"]["kind"], "local");
        assert_eq!(runtime.thread_snapshot().len(), 1);
        assert_eq!(runtime.pending_messages().len(), 1);

        let events = read_events(&journal_path(tmp.path(), "ship"));
        assert_eq!(events.len(), 2);
        assert!(matches!(events[1].kind, EventKind::UserMessage { .. }));
        server.abort();
        let _ = server.await;
        drop(runtime);

        let reopened = WaveRuntime::open("ship".into(), tmp.path().to_path_buf()).expect("reopen");
        let transcript = reopened.thread_snapshot();
        assert_eq!(transcript.len(), 1);
        assert_eq!(transcript[0].id, "turn-2");
        assert_eq!(transcript[0].text, "keep this");
    }

    #[tokio::test]
    async fn discord_backing_rejects_compose_with_open_action_and_no_local_write() {
        let tmp = tempfile::tempdir().expect("tempdir");
        let binding = crate::wave::journal::DiscordChatBinding {
            guild_id: "guild".into(),
            channel_id: "channel".into(),
        };
        let runtime = WaveRuntime::open_with_backing(
            "ship".into(),
            tmp.path().to_path_buf(),
            ChatBacking::discord(&binding),
        )
        .expect("open Discord epoch");
        let app = router_with_observer(
            runtime.clone(),
            ResidentDoor::new("resident"),
            Arc::new(ObserverSlot::new(runtime.clone(), None)),
            None,
            ShutdownDoor::new(),
        );
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0")
            .await
            .expect("bind");
        let addr = listener.local_addr().expect("address");
        let server = tokio::spawn(async move {
            axum::serve(listener, app).await.ok();
        });
        let client = reqwest::Client::new();
        let before = read_events(&journal_path(tmp.path(), "ship"));

        let response = client
            .post(format!("http://{addr}/messages"))
            .json(&serde_json::json!({"op": "message", "text": "shadow"}))
            .send()
            .await
            .expect("compose response");
        assert_eq!(response.status(), StatusCode::CONFLICT);
        let rejection: serde_json::Value = response.json().await.expect("rejection JSON");
        assert_eq!(
            rejection["epoch"]["backing"]["open"]["kind"],
            "open_discord"
        );
        assert_eq!(
            rejection["epoch"]["backing"]["open"]["url"],
            "https://discord.com/channels/guild/channel"
        );
        assert_eq!(
            read_events(&journal_path(tmp.path(), "ship")),
            before,
            "Discord rejection appends no local turn"
        );
        assert!(runtime.pending_messages().is_empty());

        let interrupt = client
            .post(format!("http://{addr}/messages"))
            .json(&serde_json::json!({"op": "interrupt", "text": ""}))
            .send()
            .await
            .expect("bare interrupt response");
        assert_eq!(interrupt.status(), StatusCode::OK);
        let interrupt: serde_json::Value = interrupt.json().await.expect("interrupt JSON");
        assert!(interrupt["message"].is_null());

        let conversation: serde_json::Value = client
            .get(format!("http://{addr}/conversation"))
            .send()
            .await
            .expect("conversation response")
            .json()
            .await
            .expect("conversation JSON");
        assert_eq!(conversation["epochs"][0]["backing"]["kind"], "discord");
        assert_eq!(
            conversation["selected_epoch_id"],
            conversation["epochs"][0]["id"]
        );
        assert_eq!(conversation["state"], "unavailable");
        assert_eq!(conversation["messages"], serde_json::json!([]));
        server.abort();
    }

    #[tokio::test]
    #[allow(clippy::await_holding_lock)] // the env guard serializes the shared registry path
    async fn observation_nudge_acquires_registry_that_appears_after_server_start() {
        let _env = crate::journal::TestLedgerGuard::new();
        let tmp = tempfile::tempdir().expect("tempdir");
        let runtime = WaveRuntime::open("ship".into(), tmp.path().to_path_buf()).expect("open");
        let observer = Arc::new(ObserverSlot::new(runtime.clone(), None));
        let app = router_with_observer(
            runtime.clone(),
            ResidentDoor::new("resident"),
            observer,
            None,
            ShutdownDoor::new(),
        );
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let addr = listener.local_addr().unwrap();
        let server = tokio::spawn(async move {
            axum::serve(listener, app).await.ok();
        });

        let response = reqwest::Client::new()
            .post(format!("http://{addr}/observations"))
            .json(&serde_json::json!({}))
            .send()
            .await
            .unwrap();
        assert_eq!(response.status(), reqwest::StatusCode::SERVICE_UNAVAILABLE);

        let store: SharedStore = Arc::new(
            open_store(&crate::store::storage_config_from_env().expect("store config"))
                .await
                .expect("create registry"),
        );
        let parent = Wave::new(
            WaveId::new(),
            "platform".to_string(),
            tmp.path().display().to_string(),
        );
        let mut child = Wave::new(
            WaveId::new(),
            "ship".to_string(),
            tmp.path().display().to_string(),
        );
        child
            .record_promotion(parent.id(), OffsetDateTime::now_utc())
            .expect("record promotion");
        store.create_wave(&parent).await.expect("store parent");
        store.create_wave(&child).await.expect("store child");

        for _ in 0..2 {
            let response = reqwest::Client::new()
                .post(format!("http://{addr}/observations"))
                .json(&serde_json::json!({"promotion": {"parent": "platform"}}))
                .send()
                .await
                .expect("promotion nudge");
            assert_eq!(response.status(), reqwest::StatusCode::NO_CONTENT);
        }
        assert_eq!(runtime.pending_messages().len(), 1);
        assert_eq!(
            read_events(&journal_path(tmp.path(), "ship"))
                .iter()
                .filter(|event| matches!(&event.kind, EventKind::PromotionObserved { .. }))
                .count(),
            1
        );
        server.abort();
    }

    /// A pointer to a dead address is stale: the probe says no live server.
    #[tokio::test]
    async fn live_endpoint_is_none_for_a_stale_pointer() {
        let tmp = tempfile::tempdir().expect("tempdir");
        assert!(live_endpoint(tmp.path(), "ship").await.is_none(), "no file");

        // A port nothing listens on: bind, learn the address, drop it.
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let dead = listener.local_addr().unwrap();
        drop(listener);
        write_endpoint(tmp.path(), "ship", dead).expect("write endpoint");
        assert!(
            live_endpoint(tmp.path(), "ship").await.is_none(),
            "dead address is stale"
        );
    }
}