dashboard events: unified coord channel + /dashboard/{stream,history}; broker forwards

hive-c0re/src/coordinator.rs

@@ -4,15 +4,23 @@
 
 use std::collections::HashMap;
 use std::path::{Path, PathBuf};
+use std::sync::atomic::{AtomicU64, Ordering};
 use std::sync::{Arc, Mutex};
 
 use anyhow::{Context, Result};
+use tokio::sync::broadcast;
 
 use crate::agent_server::{self, AgentSocket};
 use crate::approvals::Approvals;
 use crate::broker::Broker;
+use crate::dashboard_events::DashboardEvent;
 use crate::operator_questions::OperatorQuestions;
 
+/// Capacity of the dashboard event channel. Slow browser subscribers
+/// (idle tab, throttled connection) drop frames past this — that's
+/// fine, the seq dedupe makes a reconnect resync safe.
+const DASHBOARD_CHANNEL: usize = 256;
+
 const AGENT_RUNTIME_ROOT: &str = "/run/hyperhive/agents";
 const MANAGER_RUNTIME_ROOT: &str = "/run/hyperhive/manager";
 /// Manager-editable per-agent config repos. Bind-mounted RW into the manager
@@ -47,6 +55,15 @@ pub struct Coordinator {
     /// Read by the dashboard to render a spinner; cleared when the action
     /// resolves (success or failure).
     transient: Mutex<HashMap<String, TransientState>>,
+    /// Unified wire-facing event channel feeding the dashboard SSE
+    /// stream. Carries broker messages (mirrored from `broker.subscribe`
+    /// by the forwarder task in `main.rs`) and dashboard-only mutation
+    /// events (approval added/resolved, question added/answered, etc.).
+    /// Snapshot endpoints capture `event_seq` before reading state so
+    /// the client can dedupe its buffered live traffic against the
+    /// snapshot.
+    dashboard_events: broadcast::Sender<DashboardEvent>,
+    event_seq: AtomicU64,
 }
 
 /// Per-agent in-progress state that the dashboard surfaces between approve
@@ -98,6 +115,7 @@ impl Coordinator {
         let broker = Broker::open(db_path).context("open broker")?;
         let approvals = Approvals::open(db_path).context("open approvals")?;
         let questions = OperatorQuestions::open(db_path).context("open operator_questions")?;
+        let (dashboard_events, _) = broadcast::channel(DASHBOARD_CHANNEL);
         Ok(Self {
             broker: Arc::new(broker),
             approvals: Arc::new(approvals),
@@ -107,9 +125,42 @@ impl Coordinator {
             operator_pronouns,
             agents: Mutex::new(HashMap::new()),
             transient: Mutex::new(HashMap::new()),
+            dashboard_events,
+            event_seq: AtomicU64::new(0),
         })
     }
 
+    /// Subscribe to the unified dashboard event channel. Used by the
+    /// `/dashboard/stream` SSE handler and by the broker-to-dashboard
+    /// forwarder task.
+    pub fn dashboard_subscribe(&self) -> broadcast::Receiver<DashboardEvent> {
+        self.dashboard_events.subscribe()
+    }
+
+    /// Stamp the next sequence number. Each emission of a
+    /// `DashboardEvent` should fill its `seq` with `next_seq()` so the
+    /// frame the wire carries is the one the client uses to dedupe.
+    pub fn next_seq(&self) -> u64 {
+        self.event_seq.fetch_add(1, Ordering::SeqCst) + 1
+    }
+
+    /// Current high-water seq. Snapshot endpoints read this *before*
+    /// gathering state so the (snapshot.seq, snapshot) pair satisfies:
+    /// any frame with `seq > snapshot.seq` is post-snapshot. The seq
+    /// captured here may grow during snapshot construction — clients
+    /// may double-apply such events, which renderers must tolerate.
+    pub fn current_seq(&self) -> u64 {
+        self.event_seq.load(Ordering::SeqCst)
+    }
+
+    /// Broadcast a freshly-built `DashboardEvent` (caller fills `seq`
+    /// via `next_seq()`). Returns silently when there are no
+    /// subscribers — the dashboard channel is best-effort presentation
+    /// plumbing, not a delivery guarantee.
+    pub fn emit_dashboard_event(&self, event: DashboardEvent) {
+        let _ = self.dashboard_events.send(event);
+    }
+
     pub fn register_agent(self: &Arc<Self>, name: &str) -> Result<PathBuf> {
         // Idempotent: drop any existing listener so re-registration (e.g. on rebuild,
         // or after a hive-c0re restart cleared /run/hyperhive) gets a fresh socket.