feat(web): MS23-P2-002 OrchestratorPanel SSE stream component

apps/web/src/hooks/useMissionControl.ts

@@ -1,10 +1,189 @@
-interface UseMissionControlResult {
-  sessions: [];
-  loading: boolean;
-  error: null;
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { useQuery } from "@tanstack/react-query";
+import type { AgentMessageRole, AgentSessionStatus } from "@mosaic/shared";
+import { apiGet } from "@/lib/api/client";
+
+const MISSION_CONTROL_SESSIONS_QUERY_KEY = ["mission-control", "sessions"] as const;
+const SESSIONS_REFRESH_INTERVAL_MS = 15_000;
+
+export type MissionControlMessageRole = AgentMessageRole;
+
+export interface MissionControlSession {
+  id: string;
+  providerId: string;
+  providerType: string;
+  label?: string;
+  status: AgentSessionStatus;
+  parentSessionId?: string;
+  createdAt: string;
+  updatedAt: string;
+  metadata?: Record<string, unknown>;
 }
 
-// Stub — will be wired in P2-002
-export function useMissionControl(): UseMissionControlResult {
-  return { sessions: [], loading: false, error: null };
+interface MissionControlSessionsResponse {
+  sessions: MissionControlSession[];
+}
+
+export interface MissionControlStreamMessage {
+  id: string;
+  sessionId: string;
+  role: MissionControlMessageRole;
+  content: string;
+  timestamp: string;
+  metadata?: Record<string, unknown>;
+}
+
+export type MissionControlConnectionStatus = "connecting" | "connected" | "error";
+
+export interface UseSessionsResult {
+  sessions: MissionControlSession[];
+  loading: boolean;
+  error: Error | null;
+}
+
+export interface UseSessionStreamResult {
+  messages: MissionControlStreamMessage[];
+  status: MissionControlConnectionStatus;
+  error: string | null;
+}
+
+function isRecord(value: unknown): value is Record<string, unknown> {
+  return typeof value === "object" && value !== null;
+}
+
+function isMessageRole(value: unknown): value is MissionControlMessageRole {
+  return value === "assistant" || value === "system" || value === "tool" || value === "user";
+}
+
+function isMissionControlStreamMessage(value: unknown): value is MissionControlStreamMessage {
+  if (!isRecord(value)) {
+    return false;
+  }
+
+  const { id, sessionId, role, content, timestamp, metadata } = value;
+
+  if (
+    typeof id !== "string" ||
+    typeof sessionId !== "string" ||
+    !isMessageRole(role) ||
+    typeof content !== "string" ||
+    typeof timestamp !== "string"
+  ) {
+    return false;
+  }
+
+  if (metadata !== undefined && !isRecord(metadata)) {
+    return false;
+  }
+
+  return true;
+}
+
+/**
+ * Fetches Mission Control sessions.
+ */
+export function useSessions(): UseSessionsResult {
+  const query = useQuery<MissionControlSessionsResponse>({
+    queryKey: MISSION_CONTROL_SESSIONS_QUERY_KEY,
+    queryFn: async (): Promise<MissionControlSessionsResponse> => {
+      return apiGet<MissionControlSessionsResponse>("/api/mission-control/sessions");
+    },
+    refetchInterval: SESSIONS_REFRESH_INTERVAL_MS,
+  });
+
+  return {
+    sessions: query.data?.sessions ?? [],
+    loading: query.isLoading,
+    error: query.error ?? null,
+  };
+}
+
+/**
+ * Backward-compatible alias for early Mission Control integration.
+ */
+export function useMissionControl(): UseSessionsResult {
+  return useSessions();
+}
+
+/**
+ * Streams Mission Control session messages over SSE.
+ */
+export function useSessionStream(sessionId: string): UseSessionStreamResult {
+  const [messages, setMessages] = useState<MissionControlStreamMessage[]>([]);
+  const [status, setStatus] = useState<MissionControlConnectionStatus>("connecting");
+  const [error, setError] = useState<string | null>(null);
+
+  const eventSourceRef = useRef<EventSource | null>(null);
+
+  useEffect(() => {
+    if (eventSourceRef.current !== null) {
+      eventSourceRef.current.close();
+      eventSourceRef.current = null;
+    }
+
+    setMessages([]);
+    setError(null);
+
+    if (!sessionId) {
+      setStatus("connecting");
+      return;
+    }
+
+    if (typeof EventSource === "undefined") {
+      setStatus("error");
+      setError("Mission Control stream is not supported by this browser.");
+      return;
+    }
+
+    setStatus("connecting");
+
+    const source = new EventSource(
+      `/api/mission-control/sessions/${encodeURIComponent(sessionId)}/stream`
+    );
+    eventSourceRef.current = source;
+
+    source.onopen = (): void => {
+      setStatus("connected");
+      setError(null);
+    };
+
+    source.onmessage = (event: MessageEvent<string>): void => {
+      try {
+        const parsed = JSON.parse(event.data) as unknown;
+        if (!isMissionControlStreamMessage(parsed)) {
+          return;
+        }
+
+        setMessages((previousMessages) => [...previousMessages, parsed]);
+      } catch {
+        // Ignore malformed events from the stream.
+      }
+    };
+
+    source.onerror = (): void => {
+      if (source.readyState === EventSource.CONNECTING) {
+        setStatus("connecting");
+        setError(null);
+        return;
+      }
+
+      setStatus("error");
+      setError("Mission Control stream disconnected.");
+    };
+
+    return (): void => {
+      source.close();
+      if (eventSourceRef.current === source) {
+        eventSourceRef.current = null;
+      }
+    };
+  }, [sessionId]);
+
+  return {
+    messages,
+    status,
+    error,
+  };
 }