byre/web/src/state.ts

import { get, subscribe, type AgentSession, type ByreEvent, type InboxItem, type Project, type Snapshot, type Task, type User } from "./api.js";

export type Topic = "me" | "projects" | "tasks" | "sessions" | "inbox" | "selection" | "transcript" | "stream" | "connection" | "event" | "pin";

export const state = {
  me: undefined as User | undefined,
  projects: [] as Project[],
  tasks: new Map<string, Task[]>(),
  sessions: new Map<string, AgentSession[]>(),
  inbox: [] as InboxItem[],
  selectedTaskId: undefined as string | undefined,
  transcript: [] as ByreEvent[],
  lastTranscriptSeq: 0,
  pinned: undefined as number | undefined,
  connected: false,
};

const listeners = new Map<Topic, Set<(detail?: unknown) => void>>();

export function on(topic: Topic, fn: (detail?: unknown) => void): () => void {
  let set = listeners.get(topic);
  if (!set) {
    set = new Set();
    listeners.set(topic, set);
  }
  set.add(fn);
  return () => set.delete(fn);
}

export function onEach(topics: Topic[], fn: (detail?: unknown) => void): () => void {
  const offs = topics.map((t) => on(t, fn));
  return () => {
    for (const off of offs) {
      off();
    }
  };
}

export function activeTasks(): { project: Project; task: Task }[] {
  return state.projects.flatMap((project) => (state.tasks.get(project.id) ?? []).filter((t) => t.status === "active").map((task) => ({ project, task })));
}

export function notify(topic: Topic, detail?: unknown): void {
  for (const fn of listeners.get(topic) ?? []) {
    fn(detail);
  }
}

export function findTask(id: string): Task | undefined {
  for (const tasks of state.tasks.values()) {
    const task = tasks.find((t) => t.id === id);
    if (task) {
      return task;
    }
  }
  return undefined;
}

export function currentSession(taskId: string): AgentSession | undefined {
  return state.sessions.get(taskId)?.findLast((s) => s.state !== "completed") ?? state.sessions.get(taskId)?.at(-1);
}

export function snapshots(): Snapshot[] {
  return state.transcript.filter((e) => e.kind === "snapshot.created").map((e) => e.payload as unknown as Snapshot);
}

export function pinSnapshot(n: number | undefined): void {
  state.pinned = n;
  notify("pin");
}

export async function loadMe(): Promise<void> {
  state.me = await get("/api/me");
  notify("me");
}

export async function loadProjects(): Promise<void> {
  state.projects = await get("/api/projects");
  await Promise.all(state.projects.map((p) => loadTasks(p.id)));
  notify("projects");
}

export async function loadTasks(projectId: string): Promise<void> {
  const tasks = await get("/api/projects/{projectId}/tasks", { path: { projectId } });
  state.tasks.set(projectId, tasks);
  await Promise.all(tasks.filter((t) => t.status === "active").map((t) => loadSessions(t.id)));
  notify("tasks");
}

export async function loadSessions(taskId: string): Promise<void> {
  state.sessions.set(taskId, await get("/api/tasks/{taskId}/sessions", { path: { taskId } }));
  notify("sessions", taskId);
}

export async function loadInbox(): Promise<void> {
  state.inbox = await get("/api/inbox");
  notify("inbox");
}

let closeTaskStream: (() => void) | undefined;
let taskBuffer: ByreEvent[] = [];
let taskFlush = 0;

const visitsKey = "byre.visits";

export function lastVisits(): Record<string, number> {
  return JSON.parse(localStorage.getItem(visitsKey) ?? "{}") as Record<string, number>;
}

function markVisited(taskId: string | undefined): void {
  if (!taskId) {
    return;
  }
  localStorage.setItem(visitsKey, JSON.stringify({ ...lastVisits(), [taskId]: Date.now() }));
}

export function selectTask(taskId: string | undefined): void {
  markVisited(state.selectedTaskId);
  markVisited(taskId);
  closeTaskStream?.();
  closeTaskStream = undefined;
  clearTimeout(taskFlush);
  taskFlush = 0;
  taskBuffer = [];
  state.selectedTaskId = taskId;
  state.transcript = [];
  state.lastTranscriptSeq = 0;
  state.pinned = undefined;
  notify("selection");

  if (!taskId) {
    return;
  }

  closeTaskStream = subscribe(0, taskId, queueTaskEvent, () => undefined);
}

function queueTaskEvent(ev: ByreEvent): void {
  taskBuffer.push(ev);
  if (!taskFlush) {
    taskFlush = setTimeout(flushTaskEvents, 0);
  }
}

function flushTaskEvents(): void {
  const events = taskBuffer;
  taskBuffer = [];
  taskFlush = 0;
  let stored: ByreEvent[] = [];
  for (const ev of events) {
    if (ev.seq !== 0) {
      stored.push(ev);
      continue;
    }
    appendTranscript(stored);
    stored = [];
    notify("stream", ev);
  }
  appendTranscript(stored);
}

function appendTranscript(events: ByreEvent[]): void {
  const fresh = events.filter((ev) => ev.seq > state.lastTranscriptSeq);
  if (fresh.length === 0) {
    return;
  }
  state.transcript.push(...fresh);
  state.lastTranscriptSeq = fresh.at(-1)!.seq;
  notify("transcript", fresh);
}

export function handleEvent(ev: ByreEvent): void {
  if (ev.seq === 0) {
    notify("event", ev);
    return;
  }

  switch (ev.kind) {
    case "user.updated":
      if (ev.payload["login"] === state.me?.login) {
        void loadMe();
      }
      break;
    case "project.created":
      void loadProjects();
      break;
    case "task.created":
    case "task.merge_title":
    case "task.merged":
    case "task.discarded":
      if (ev.project_id) {
        void loadTasks(ev.project_id);
      }
      break;
    case "session.created":
    case "session.state":
    case "session.model":
      if (ev.task_id) {
        void loadSessions(ev.task_id);
      }
      break;
    case "inbox.created":
    case "inbox.updated":
      void loadInbox();
      break;
  }

  notify("event", ev);
}