feat: extract lightweight agent directory (Phase 1)

packages/app/src/stores/session-store.ts

@@ -1,5 +1,6 @@
 import { useSyncExternalStore } from "react";
 import type { SessionContextValue } from "@/contexts/session-context";
+import type { AgentDirectoryEntry } from "@/types/agent-directory";
 import { isPerfLoggingEnabled, measurePayload, perfLog } from "@/utils/perf";
 
 // SessionData mirrors SessionContextValue so consumers can subscribe to a single source of truth.
@@ -7,6 +8,7 @@ export type SessionData = SessionContextValue;
 
 interface SessionStoreState {
   sessions: Record<string, SessionData>;
+  agentDirectory: Record<string, AgentDirectoryEntry[]>;
 }
 
 interface SessionStore extends SessionStoreState {
@@ -14,11 +16,14 @@ interface SessionStore extends SessionStoreState {
   updateSession: (serverId: string, partial: Partial<SessionData>) => void;
   clearSession: (serverId: string) => void;
   getSession: (serverId: string) => SessionData | undefined;
+  setAgentDirectory: (serverId: string, agents: AgentDirectoryEntry[]) => void;
+  clearAgentDirectory: (serverId: string) => void;
+  getAgentDirectory: (serverId: string) => AgentDirectoryEntry[] | undefined;
 }
 
 type SessionListener = () => void;
 
-let storeState: SessionStoreState = { sessions: {} };
+let storeState: SessionStoreState = { sessions: {}, agentDirectory: {} };
 const listeners = new Set<SessionListener>();
 const SESSION_STORE_LOG_TAG = "[SessionStore]";
 let sessionStoreUpdateCount = 0;
@@ -30,7 +35,7 @@ const emit = () => {
 };
 
 const logSessionStoreUpdate = (
-  type: "setSession" | "updateSession" | "clearSession",
+  type: "setSession" | "updateSession" | "clearSession" | "setAgentDirectory" | "clearAgentDirectory",
   serverId: string,
   payload?: unknown
 ) => {
@@ -65,6 +70,7 @@ const setSession: SessionStore["setSession"] = (serverId, data) => {
     }
     logSessionStoreUpdate("setSession", serverId, data);
     return {
+      ...prev,
       sessions: {
         ...prev.sessions,
         [serverId]: data,
@@ -92,6 +98,7 @@ const updateSession: SessionStore["updateSession"] = (serverId, partial) => {
 
     logSessionStoreUpdate("updateSession", serverId, partial);
     return {
+      ...prev,
       sessions: {
         ...prev.sessions,
         [serverId]: next,
@@ -108,7 +115,7 @@ const clearSession: SessionStore["clearSession"] = (serverId) => {
     logSessionStoreUpdate("clearSession", serverId);
     const nextSessions = { ...prev.sessions };
     delete nextSessions[serverId];
-    return { sessions: nextSessions };
+    return { ...prev, sessions: nextSessions };
   });
 };
 
@@ -116,6 +123,39 @@ const getSession: SessionStore["getSession"] = (serverId) => {
   return storeState.sessions[serverId];
 };
 
+const setAgentDirectory: SessionStore["setAgentDirectory"] = (serverId, agents) => {
+  updateStoreState((prev) => {
+    const existing = prev.agentDirectory[serverId];
+    if (existing && areAgentDirectoriesEqual(existing, agents)) {
+      return prev;
+    }
+    logSessionStoreUpdate("setAgentDirectory", serverId, { agentCount: agents.length });
+    return {
+      ...prev,
+      agentDirectory: {
+        ...prev.agentDirectory,
+        [serverId]: agents,
+      },
+    };
+  });
+};
+
+const clearAgentDirectory: SessionStore["clearAgentDirectory"] = (serverId) => {
+  updateStoreState((prev) => {
+    if (!(serverId in prev.agentDirectory)) {
+      return prev;
+    }
+    logSessionStoreUpdate("clearAgentDirectory", serverId);
+    const nextDirectory = { ...prev.agentDirectory };
+    delete nextDirectory[serverId];
+    return { ...prev, agentDirectory: nextDirectory };
+  });
+};
+
+const getAgentDirectory: SessionStore["getAgentDirectory"] = (serverId) => {
+  return storeState.agentDirectory[serverId];
+};
+
 const subscribe = (listener: SessionListener) => {
   listeners.add(listener);
   return () => {
@@ -125,10 +165,14 @@ const subscribe = (listener: SessionListener) => {
 
 const buildSnapshot = (): SessionStore => ({
   sessions: storeState.sessions,
+  agentDirectory: storeState.agentDirectory,
   setSession,
   updateSession,
   clearSession,
   getSession,
+  setAgentDirectory,
+  clearAgentDirectory,
+  getAgentDirectory,
 });
 
 const shallowEqual = (left: SessionData, right: SessionData): boolean => {
@@ -155,3 +199,33 @@ export function useSessionStore<T>(selector: (state: SessionStore) => T): T {
     () => selector(buildSnapshot())
   );
 }
+
+function areAgentDirectoriesEqual(
+  left: AgentDirectoryEntry[] | undefined,
+  right: AgentDirectoryEntry[]
+): boolean {
+  if (!left) {
+    return false;
+  }
+  if (left.length !== right.length) {
+    return false;
+  }
+  const leftById = new Map(left.map((entry) => [entry.id, entry]));
+  for (const entry of right) {
+    const previous = leftById.get(entry.id);
+    if (!previous) {
+      return false;
+    }
+    if (
+      previous.serverId !== entry.serverId ||
+      previous.title !== entry.title ||
+      previous.status !== entry.status ||
+      previous.provider !== entry.provider ||
+      previous.cwd !== entry.cwd ||
+      previous.lastActivityAt.getTime() !== entry.lastActivityAt.getTime()
+    ) {
+      return false;
+    }
+  }
+  return true;
+}