feat(#1187): dynamic terminal scrollback with paginated history

hive-ag3nt/src/web_ui.rs

@@ -717,15 +717,41 @@ async fn post_send(State(state): State<AppState>, Form(form): Form<SendForm>) ->
     }
 }
 
-async fn events_history(State(state): State<AppState>) -> axum::Json<serde_json::Value> {
-    // Capture seq *before* the read so dedupe is "drop buffered events
-    // you've already seen in history", never "lose an event that fired
-    // between the read and the timestamp." Historical rows have no
-    // per-row seq; only the high-water mark matters for the dedupe
-    // window.
-    let seq = state.bus.current_seq();
-    let events = state.bus.history();
-    axum::Json(serde_json::json!({ "seq": seq, "events": events }))
+/// Query params for the paginated history endpoint.
+#[derive(Debug, Deserialize)]
+struct HistoryParams {
+    /// Cursor: only return events with sqlite row id < `before`.
+    /// Omit for the initial (most-recent) page.
+    before: Option<i64>,
+    /// Page size (default 100, capped at HISTORY_CAPACITY).
+    limit: Option<usize>,
+}
+
+async fn events_history(
+    State(state): State<AppState>,
+    axum::extract::Query(params): axum::extract::Query<HistoryParams>,
+) -> axum::Json<serde_json::Value> {
+    use crate::events::HISTORY_CAPACITY;
+    let limit = params.limit.unwrap_or(100).min(HISTORY_CAPACITY);
+    let before = params.before;
+    let is_initial = before.is_none();
+
+    // Capture seq *before* the read on initial loads so the SSE dedupe
+    // window is "drop buffered events you've already seen in history",
+    // never "lose an event that fired between the read and the seq."
+    // On paginated loads (`before` is set) seq is not needed.
+    let seq = if is_initial { Some(state.bus.current_seq()) } else { None };
+
+    let (events, min_id, has_more) = state.bus.history_page(before, limit);
+    let mut resp = serde_json::json!({
+        "events": events,
+        "min_id": min_id,
+        "has_more": has_more,
+    });
+    if let Some(s) = seq {
+        resp["seq"] = serde_json::json!(s);
+    }
+    axum::Json(resp)
 }
 
 async fn events_stream(