// Turns T3 state into the shapes in contract.ts. Thread shells carry status but not text, so the
// last message and the pending request's details come from each thread's bounded snapshot. Those
// are large (hundreds of KB), so they are reduced to a small summary and cached per thread until
// the thread's `updatedAt` moves.

import { resolvePhase, threadPhase, type Phase } from "./awareness.ts";
import type {
  Activity,
  AgentProvider,
  ChangedFile,
  PendingFile,
  Feed,
  FeedItem,
  HostStatusDetail,
  HostSummary,
  Message,
  PendingRequest,
  RecentResponse,
  RouteKind,
  Summary,
  ThreadDetail,
  ThreadRow,
  HistoryResponse,
  SearchResponse,
} from "./contract.ts";
import type { T3Host } from "./t3/host.ts";
import {
  isApprovalRequest,
  isUserInputRequest,
  type BoundedThread,
  type ConversationMessage,
  type ThreadShell,
  type TurnItem,
} from "./t3/types.ts";

const LAST_MESSAGE_CHARS = 280;
const MESSAGE_CHARS = 2000;
const MESSAGES_PER_THREAD = 20;
const ACTIVITY_CHARS = 80;
/** How long a running thread's summary stays fresh. Its steps change without moving `updatedAt`. */
const RUNNING_SUMMARY_MS = 5_000;
const THREAD_LIST_LIMIT = 50;
const RECENT_LIMIT = 10;
/** How long a feed request waits for summaries it does not have yet. */
const SUMMARY_WAIT_MS = 2_000;

export interface ThreadSummary {
  messages: Message[];
  lastAssistantMessage: string | null;
  request: PendingRequest | null;
  activity: Activity | null;
  /** The files the latest run in the window changed. */
  changedFiles: ChangedFile[];
  /** The history route's cursor for messages before `messages`. */
  earlierCursor: string | null;
}

/** Trims text for a small screen: collapses whitespace and cuts at a word near `max`. */
export function trimText(text: string, max: number): string {
  const flat = text.replace(/\s+/g, " ").trim();
  if (flat.length <= max) return flat;
  const cut = flat.slice(0, max);
  const space = cut.lastIndexOf(" ");
  return `${(space > max * 0.6 ? cut.slice(0, space) : cut).trimEnd()}…`;
}

/** Reduces a bounded thread snapshot to what the watch shows. */
export function summarize(bounded: BoundedThread, thread: ThreadShell): ThreadSummary {
  const { messages, turnItems } = bounded.projection;
  const visible = visibleMessages(messages);
  const lastAssistant = visible.findLast((message) => message.role === "assistant");
  const start = Math.max(0, visible.length - MESSAGES_PER_THREAD);
  return {
    messages: visible.slice(start).map(toMessage),
    lastAssistantMessage: lastAssistant ? trimText(lastAssistant.text, LAST_MESSAGE_CHARS) : null,
    request: pendingRequest(thread, turnItems),
    activity: currentActivity(turnItems),
    changedFiles: latestChanges(turnItems),
    earlierCursor: windowCursor(start, bounded),
  };
}

const visibleMessages = (messages: ConversationMessage[]) =>
  messages.filter((message) => message.text.trim().length > 0 && (message.role === "user" || message.role === "assistant"));

const toMessage = (message: Pick<ConversationMessage, "id" | "role" | "text" | "createdAt">): Message => ({
  id: message.id,
  role: message.role as Message["role"],
  text: message.text.length > MESSAGE_CHARS ? `${message.text.slice(0, MESSAGE_CHARS)}…` : message.text,
  createdAt: message.createdAt,
});

// History cursors are the gateway's own. `w<n>` means the bounded window's messages before index n,
// which the thread detail leaves out past its 20. `h<cursor>` is T3's cursor for older pages.

/** The cursor for what comes before the window's message `start`. */
function windowCursor(start: number, bounded: BoundedThread): string | null {
  if (start > 0) return `w${start}`;
  return bounded.hasMoreHistory && bounded.historyCursor ? `h${bounded.historyCursor}` : null;
}

/**
 * The messages before `cursor`: 20 from the bounded window, or one T3 page, which can hold more.
 * T3 pages without messages are skipped, three at most.
 */
export async function loadHistory(host: T3Host, thread: ThreadShell, cursor: string): Promise<HistoryResponse> {
  if (cursor.startsWith("w")) {
    const end = Number(cursor.slice(1));
    const bounded = await host.bounded(thread.id);
    const visible = visibleMessages(bounded.projection.messages);
    const start = Math.max(0, Math.min(end, visible.length) - MESSAGES_PER_THREAD);
    return { messages: visible.slice(start, end).map(toMessage), earlierCursor: windowCursor(start, bounded) };
  }
  let next: string | null = cursor.slice(1);
  for (let pages = 0; next && pages < 3; pages++) {
    const page = await host.history(thread.id, next);
    next = page.hasMoreHistory ? page.nextCursor : null;
    const messages = page.items
      .map(({ item }) => item)
      .filter(
        (item) =>
          (item.type === "user_message" || item.type === "assistant_message") && (item.text ?? "").trim().length > 0,
      )
      .map((item) =>
        toMessage({
          id: item.messageId ?? "",
          role: item.type === "user_message" ? "user" : "assistant",
          text: item.text ?? "",
          createdAt: item.startedAt ?? item.updatedAt ?? "",
        }),
      );
    if (messages.length > 0) return { messages, earlierCursor: next && `h${next}` };
  }
  return { messages: [], earlierCursor: next && `h${next}` };
}

/** The files the latest run changed, summed per file, most lines changed first. */
export function latestChanges(turnItems: TurnItem[]): ChangedFile[] {
  const runId = turnItems.findLast((item) => item.runId)?.runId;
  if (!runId) return [];
  const files = new Map<string, ChangedFile>();
  for (const item of turnItems) {
    if (item.type !== "file_change" || item.runId !== runId || !item.fileName) continue;
    const file = files.get(item.fileName) ?? { path: item.fileName, name: item.fileName.split("/").pop()!, additions: 0, deletions: 0 };
    file.additions += item.additions ?? 0;
    file.deletions += item.deletions ?? 0;
    files.set(item.fileName, file);
  }
  return [...files.values()].sort((a, b) => b.additions + b.deletions - (a.additions + a.deletions));
}

/** The newest step still in progress, said briefly. Monitors are left out, as they run for hours. */
export function currentActivity(turnItems: TurnItem[]): Activity | null {
  for (let i = turnItems.length - 1; i >= 0; i--) {
    const item = turnItems[i]!;
    if (item.status !== "running" && item.status !== "pending") continue;
    const step = describeStep(item);
    if (step) return { ...step, text: trimText(step.text, ACTIVITY_CHARS), startedAt: item.startedAt ?? null };
  }
  return null;
}

function describeStep(item: TurnItem): Omit<Activity, "startedAt"> | null {
  switch (item.type) {
    case "command_execution":
      return item.monitor || typeof item.input !== "string"
        ? null
        : { kind: "command", text: item.input.split("\n").find((line) => line.trim()) ?? item.input };
    case "file_change":
      return item.fileName ? { kind: "edit", text: item.fileName.split("/").pop()! } : null;
    case "file_search":
      return { kind: "search", text: item.pattern ?? item.title ?? "files" };
    case "web_search":
      return { kind: "web", text: item.title ?? "the web" };
    case "subagent":
      return { kind: "subagent", text: item.title ?? "Subagent" };
    case "reasoning":
      return { kind: "thinking", text: "Thinking" };
    case "dynamic_tool":
      return item.toolName || item.title ? { kind: "tool", text: (item.toolName ?? item.title)! } : null;
    default:
      return null;
  }
}

function pendingRequest(thread: ThreadShell, turnItems: BoundedThread["projection"]["turnItems"]): PendingRequest | null {
  const pending = thread.pendingRuntimeRequest;
  if (!pending || pending.kind === "auth_refresh") return null;
  const base = { id: pending.id, kind: pending.kind, prompt: null, reason: null, options: [], files: [], questions: [] };
  const item = turnItems.findLast(
    (candidate) => (isApprovalRequest(candidate) || isUserInputRequest(candidate)) && candidate.requestId === pending.id,
  );
  if (item && isApprovalRequest(item)) {
    const options = item.options?.length
      ? item.options.map(({ decision, label, warning }) => ({ decision, label, ...(warning ? { warning } : {}) }))
      : [
          { decision: "accept" as const, label: "Allow" },
          { decision: "decline" as const, label: "Deny" },
        ];
    const prompt = item.prompt ?? item.title ?? null;
    const files = pending.kind === "file-change" ? pendingFiles(turnItems, item.runId, prompt) : [];
    return { ...base, prompt, reason: item.reason ?? null, options, files };
  }
  if (item && isUserInputRequest(item)) {
    return {
      ...base,
      questions: item.questions.map((question) => ({
        id: question.id,
        header: question.header,
        question: question.question,
        options: question.options.map((option) => ({ label: option.label, value: option.value ?? option.label })),
        allowCustomAnswer: question.allowCustomAnswer ?? false,
        multiSelect: question.multiSelect ?? false,
      })),
    };
  }
  // The turn item may not be in the bounded window yet. Offer the plain choices for approvals.
  return pending.kind === "user_input"
    ? base
    : {
        ...base,
        options: [
          { decision: "accept", label: "Allow" },
          { decision: "decline", label: "Deny" },
        ],
      };
}

const PREVIEW_LINES = 4;
const PREVIEW_CHARS = 60;

/**
 * The files a file-change approval would touch: the run's unfinished file changes, or failing
 * those, the path in the prompt, which Claude words as `Edit: <path>`. Most providers send the
 * diff only after the edit runs, so counts and preview are usually empty.
 */
export function pendingFiles(turnItems: TurnItem[], runId: string | null | undefined, prompt: string | null): PendingFile[] {
  const files = turnItems
    .filter(
      (item) =>
        item.type === "file_change" &&
        item.fileName &&
        (!runId || item.runId === runId) &&
        item.status !== "completed" &&
        item.status !== "failed" &&
        item.status !== "cancelled",
    )
    .map((item) => {
      const preview = (item.diffStr ?? "")
        .split("\n")
        .filter((line) => /^[+-]/.test(line) && !/^(\+\+\+|---)( |$)/.test(line))
        .slice(0, PREVIEW_LINES)
        .map((line) => (line.length > PREVIEW_CHARS ? `${line.slice(0, PREVIEW_CHARS)}…` : line));
      return {
        path: item.fileName!,
        name: item.fileName!.split("/").pop()!,
        additions: item.additions ?? null,
        deletions: item.deletions ?? null,
        preview,
      };
    });
  if (files.length > 0) return files;
  const path = prompt?.match(/^\w+: (\S.*)$/)?.[1]?.trim();
  return path ? [{ path, name: path.split("/").pop()!, additions: null, deletions: null, preview: [] }] : [];
}

/** Per-thread summaries, refetched when a thread's `updatedAt` changes. */
export class SummaryCache {
  private readonly entries = new Map<string, { updatedAt: string; fetchedAt: number; summary: ThreadSummary }>();
  private readonly inflight = new Map<string, Promise<ThreadSummary>>();

  constructor(private readonly log: (message: string) => void = () => {}) {}

  /** The cached summary, if it matches the thread's current version and, while running, is recent. */
  peek(host: T3Host, thread: ThreadShell): ThreadSummary | undefined {
    const entry = this.entries.get(key(host, thread.id));
    if (entry?.updatedAt !== thread.updatedAt) return undefined;
    if (thread.activeRunId !== null && Date.now() - entry.fetchedAt > RUNNING_SUMMARY_MS) return undefined;
    return entry.summary;
  }

  get(host: T3Host, thread: ThreadShell): Promise<ThreadSummary> {
    const cached = this.peek(host, thread);
    if (cached) return Promise.resolve(cached);
    const k = `${key(host, thread.id)}@${thread.updatedAt}`;
    const fetchedAt = Date.now();
    const running = this.inflight.get(k);
    if (running) return running;
    const promise = host
      .bounded(thread.id)
      .then((bounded) => {
        const summary = summarize(bounded, thread);
        this.entries.set(key(host, thread.id), { updatedAt: thread.updatedAt, fetchedAt, summary });
        return summary;
      })
      .finally(() => this.inflight.delete(k));
    this.inflight.set(k, promise);
    return promise;
  }

  forget(host: T3Host, threadId: string) {
    this.entries.delete(key(host, threadId));
  }
}

const key = (host: T3Host, threadId: string) => `${host.id}:${threadId}`;

export const hostSummary = (host: T3Host): HostSummary => ({
  id: host.id,
  label: host.label,
  status: host.status,
  error: host.lastError,
});

/** A host with its routes, for the status screens. `tokenExpiresAt` comes from the hosts table. */
export function hostStatusDetail(host: T3Host, tokenExpiresAt: string | null): HostStatusDetail {
  return {
    ...hostSummary(host),
    activeUrl: host.status === "online" ? host.url : null,
    routes: host.config.urls.map((url) => {
      const attempt = host.routeAttempts.get(url);
      return {
        url,
        kind: routeKind(url),
        result: attempt ? (attempt.ok ? "ok" : "failed") : "untried",
        error: attempt?.error ?? null,
        checkedAt: attempt?.at ?? null,
      };
    }),
    onlineSince: host.onlineSince,
    lastOnlineAt: host.lastOnlineAt,
    nextRetryAt: host.nextRetryAt,
    tokenExpiresAt,
    serverVersion: host.serverVersion,
  };
}

export function routeKind(url: string): RouteKind {
  const { protocol, hostname } = new URL(url);
  if (protocol === "https:") return "public";
  return hostname.includes("vpn") ? "vpn" : "direct";
}

/** A thread on the feed. With `via`, the card shows that subagent's request on this thread. */
interface Candidate {
  host: T3Host;
  thread: ThreadShell;
  phase: Phase;
  via?: { host: T3Host; thread: ThreadShell; phase: Phase };
}

const isWaiting = (phase: Phase | null) => phase === "waiting_for_approval" || phase === "waiting_for_input";

/** The thread that delegated `child`, if the gateway is connected to its host. */
function delegator(hosts: T3Host[], child: ThreadShell): { host: T3Host; thread: ThreadShell } | null {
  const from = child.delegatedFrom;
  if (!from) return null;
  const host = hosts.find((candidate) => candidate.config.environmentId === from.environmentId);
  const thread = host?.threads.get(from.threadId);
  return host && thread ? { host, thread } : null;
}

/**
 * Moves each waiting subagent's request onto the card of the thread that delegated it, the oldest
 * request first. A subagent keeps its own card when its parent is unknown, hidden, archived, or
 * already showing a request.
 */
function attachDelegates(candidates: Candidate[], hosts: T3Host[]): Candidate[] {
  const result = [...candidates];
  const delegates = candidates
    .filter(({ thread, phase }) => thread.delegatedFrom && isWaiting(phase))
    .sort((a, b) => requestAge(a.thread).localeCompare(requestAge(b.thread)));
  for (const child of delegates) {
    const parent = delegator(hosts, child.thread);
    const index = parent ? result.findIndex(({ host, thread }) => host === parent.host && thread.id === parent.thread.id) : -1;
    const card = result[index];
    const own = result.indexOf(child);
    if (!card || own === -1 || card.via || isWaiting(card.phase)) continue;
    result[index] = { ...card, phase: child.phase, via: { host: child.host, thread: child.thread, phase: child.phase } };
    result.splice(own, 1);
  }
  return result;
}

const requestAge = (thread: ThreadShell) => thread.pendingRuntimeRequest?.createdAt ?? "";

function feedItem(
  host: T3Host,
  thread: ThreadShell,
  phase: Phase,
  summary: ThreadSummary | undefined,
  via?: { host: T3Host; thread: ThreadShell; summary: ThreadSummary | undefined },
): FeedItem {
  return {
    hostId: host.id,
    hostLabel: host.label,
    threadId: thread.id,
    projectId: thread.projectId,
    projectTitle: host.projects.get(thread.projectId)?.title ?? "",
    title: thread.title,
    phase,
    updatedAt: thread.updatedAt,
    lastMessage: summary?.lastAssistantMessage ?? null,
    activity: summary?.activity ?? null,
    snoozedUntil: isSnoozed(thread, Date.now()) ? thread.snoozedUntil! : null,
    changes: summary?.changedFiles.length
      ? {
          files: summary.changedFiles.length,
          additions: summary.changedFiles.reduce((sum, file) => sum + file.additions, 0),
          deletions: summary.changedFiles.reduce((sum, file) => sum + file.deletions, 0),
        }
      : null,
    request: (via ? via.summary : summary)?.request ?? null,
    via: via ? { hostId: via.host.id, threadId: via.thread.id, title: via.thread.title } : null,
  };
}

/** The longest waiting subagent that `parent` delegated to, if any. */
function waitingDelegate(hosts: T3Host[], parentHost: T3Host, parent: ThreadShell): Candidate | undefined {
  let oldest: Candidate | undefined;
  for (const host of hosts) {
    for (const thread of host.threads.values()) {
      const from = thread.delegatedFrom;
      if (from?.threadId !== parent.id || from.environmentId !== parentHost.config.environmentId) continue;
      const phase = threadPhase(thread);
      if (!isWaiting(phase) || thread.archivedAt || thread.deletedAt) continue;
      if (!oldest || requestAge(thread) < requestAge(oldest.thread)) oldest = { host, thread, phase: phase! };
    }
  }
  return oldest;
}

/** Counts for the complication, from thread shells alone. */
/**
 * Counts for the complication, plus the longest waiting request and the busiest working thread.
 * Reads at most those two threads, waiting briefly as the feed does.
 */
export async function buildSummary(hosts: T3Host[], cache: SummaryCache): Promise<Summary> {
  let needsYou = 0;
  let working = 0;
  let next: { host: T3Host; thread: ThreadShell } | null = null;
  let current: { host: T3Host; thread: ThreadShell } | null = null;
  for (const host of hosts) {
    for (const thread of host.threads.values()) {
      if (thread.archivedAt || thread.deletedAt) continue;
      const phase = threadPhase(thread);
      if (phase === "starting" || phase === "running") {
        working++;
        if (!current || thread.updatedAt > current.thread.updatedAt) current = { host, thread };
      }
      if (phase !== "waiting_for_approval" && phase !== "waiting_for_input") continue;
      needsYou++;
      const waitingSince = thread.pendingRuntimeRequest?.createdAt ?? "";
      if (!next || waitingSince < (next.thread.pendingRuntimeRequest?.createdAt ?? "")) next = { host, thread };
    }
  }
  const read = [next, current].filter((pick) => pick !== null);
  const missing = read.filter(({ host, thread }) => !cache.peek(host, thread));
  if (missing.length > 0) {
    await Promise.race([
      Promise.all(missing.map(({ host, thread }) => cache.get(host, thread).catch(() => undefined))),
      Bun.sleep(SUMMARY_WAIT_MS),
    ]);
  }
  const request = next && cache.peek(next.host, next.thread)?.request;
  const asked = request?.prompt ?? request?.questions[0]?.question;
  return {
    needsYou,
    working,
    next: next && {
      hostId: next.host.id,
      threadId: next.thread.id,
      title: next.thread.title,
      hostLabel: next.host.label,
      request: asked ? trimText(asked, ACTIVITY_CHARS) : null,
    },
    current: current && {
      hostId: current.host.id,
      threadId: current.thread.id,
      title: current.thread.title,
      activity: cache.peek(current.host, current.thread)?.activity ?? null,
    },
    hostsOffline: hosts.filter((host) => host.status !== "online").length,
  };
}

/** True while a snooze is set and its time has not come. */
const isSnoozed = (thread: ThreadShell, now: number) =>
  !!thread.snoozedUntil && Date.parse(thread.snoozedUntil) > now;

/** Every thread the feed shows, in feed order, with subagent requests on their parents' cards. */
export function feedCandidates(hosts: T3Host[], now = Date.now()) {
  const found: Candidate[] = [];
  for (const host of hosts) {
    for (const thread of host.threads.values()) {
      const phase = threadPhase(thread);
      if (phase === null || thread.archivedAt || thread.deletedAt) continue;
      found.push({ host, thread, phase });
    }
  }
  const candidates = attachDelegates(found, hosts);

  const byNewest = (a: { thread: ThreadShell }, b: { thread: ThreadShell }) =>
    b.thread.updatedAt.localeCompare(a.thread.updatedAt);
  const asker = (candidate: Candidate) => candidate.via?.thread ?? candidate.thread;
  const finished = candidates.filter(({ phase }) => phase === "completed" || phase === "failed");
  return {
    needsYou: candidates
      .filter(({ phase }) => isWaiting(phase))
      .sort((a, b) => requestAge(asker(a)).localeCompare(requestAge(asker(b)))),
    working: candidates.filter(({ phase }) => phase === "starting" || phase === "running").sort(byNewest),
    /** Finished and failed threads not yet settled or snoozed, however old. */
    recent: finished.filter(({ thread }) => !isSnoozed(thread, now)).sort(byNewest),
    /** Finished threads snoozed for later, the soonest to come back first. */
    snoozed: finished
      .filter(({ thread }) => isSnoozed(thread, now))
      .sort((a, b) => a.thread.snoozedUntil!.localeCompare(b.thread.snoozedUntil!)),
  };
}

const toItem =
  (cache: SummaryCache) =>
  ({ host, thread, phase, via }: Candidate): FeedItem =>
    feedItem(host, thread, phase, cache.peek(host, thread), via && { ...via, summary: cache.peek(via.host, via.thread) });

/** Builds the feed across every host, waiting briefly for summaries it has not read yet. */
export async function buildFeed(hosts: T3Host[], cache: SummaryCache): Promise<Feed> {
  const { needsYou, working, recent: allRecent, snoozed } = feedCandidates(hosts);
  const recent = allRecent.slice(0, RECENT_LIMIT);

  const shown = [...needsYou, ...working, ...recent].flatMap((candidate) => (candidate.via ? [candidate, candidate.via] : [candidate]));
  const missing = shown
    .filter(({ host, thread }) => !cache.peek(host, thread))
    .map(({ host, thread }) => cache.get(host, thread).catch(() => undefined));
  if (missing.length > 0) await Promise.race([Promise.all(missing), Bun.sleep(SUMMARY_WAIT_MS)]);

  return {
    needsYou: needsYou.map(toItem(cache)),
    working: working.map(toItem(cache)),
    recent: recent.map(toItem(cache)),
    recentTotal: allRecent.length,
    snoozedTotal: snoozed.length,
    hosts: hosts.map(hostSummary),
  };
}

/**
 * Every unsettled finished thread, for the full Recent list. Uses only summaries already cached,
 * since there can be many, so `lastMessage` is null for threads the gateway has not read.
 */
export function buildRecent(hosts: T3Host[], cache: SummaryCache): RecentResponse {
  return { items: feedCandidates(hosts).recent.map(toItem(cache)) };
}

/** Snoozed finished threads, the soonest to come back first. Cached summaries only, like Recent. */
export function buildSnoozed(hosts: T3Host[], cache: SummaryCache): RecentResponse {
  return { items: feedCandidates(hosts).snoozed.map(toItem(cache)) };
}

/**
 * One thread with its recent messages. Fetches the summary if it is not cached. When the thread
 * has no request of its own but a subagent it delegated to is waiting, shows that request.
 */
export async function buildThreadDetail(
  host: T3Host,
  thread: ThreadShell,
  cache: SummaryCache,
  hosts: T3Host[],
): Promise<ThreadDetail> {
  const summary = await cache.get(host, thread);
  const own = threadPhase(thread) ?? (thread.status === "failed" ? "failed" : "completed");
  const child = isWaiting(own) ? undefined : waitingDelegate(hosts, host, thread);
  const via = child && { host: child.host, thread: child.thread, summary: await cache.get(child.host, child.thread).catch(() => undefined) };
  return {
    item: feedItem(host, thread, child?.phase ?? own, summary, via),
    messages: summary.messages,
    canStop: thread.activeRunId !== null,
    askFirst: thread.runtimeMode === ASK_FIRST,
    earlierCursor: summary.earlierCursor,
    subagents: subagents(hosts, host, thread),
    changedFiles: summary.changedFiles,
  };
}

const threadRow = (host: T3Host, thread: ThreadShell): ThreadRow => ({
  hostId: host.id,
  threadId: thread.id,
  title: thread.title,
  phase: resolvePhase(thread),
  settled: thread.settledOverride === "settled",
  updatedAt: thread.updatedAt,
});

const newestFirst = (a: ThreadRow, b: ThreadRow) => b.updatedAt.localeCompare(a.updatedAt);
const isLive = (thread: ThreadShell) => !thread.archivedAt && !thread.deletedAt;

/** The subagents `parent` started, its own and the ones it delegated to on any host. */
function subagents(hosts: T3Host[], parentHost: T3Host, parent: ThreadShell): ThreadRow[] {
  const rows: ThreadRow[] = [];
  for (const host of hosts) {
    for (const thread of host.threads.values()) {
      if (!isLive(thread)) continue;
      const native =
        host === parentHost &&
        thread.lineage.relationshipToParent === "subagent" &&
        thread.lineage.parentThreadId === parent.id;
      const from = thread.delegatedFrom;
      const delegated = from?.threadId === parent.id && from.environmentId === parentHost.config.environmentId;
      if (native || delegated) rows.push(threadRow(host, thread));
    }
  }
  return rows.sort(newestFirst);
}

/**
 * Searches every online host at once and merges the hits, newest match first. Hosts that are
 * offline or fail are named in `unsearched`.
 */
export async function searchThreads(hosts: T3Host[], query: string): Promise<SearchResponse> {
  const results = await Promise.all(
    hosts.map(async (host) => {
      if (host.status !== "online") return null;
      try {
        return { host, matches: await host.search(query) };
      } catch {
        return null;
      }
    }),
  );
  const hits = results.flatMap((result) =>
    (result?.matches ?? []).flatMap((match) => {
      const thread = result!.host.threads.get(match.threadId);
      if (!thread || !isLive(thread)) return [];
      const snippet = match.snippet.trim();
      return [
        {
          thread: threadRow(result!.host, thread),
          projectTitle: result!.host.projects.get(thread.projectId)?.title ?? "",
          hostLabel: result!.host.label,
          snippet: snippet && snippet !== thread.title ? trimText(snippet, 160) : null,
          at: match.messageCreatedAt ?? thread.updatedAt,
        },
      ];
    }),
  );
  return {
    hits: hits.sort((a, b) => b.at.localeCompare(a.at)).map(({ at: _, ...hit }) => hit),
    unsearched: hosts.filter((host, i) => results[i] === null).map((host) => host.label),
  };
}

/** A project's newest 50 threads, settled ones included. Subagents are listed under their parents. */
export function projectThreads(host: T3Host, projectId: string): ThreadRow[] {
  return [...host.threads.values()]
    .filter(
      (thread) =>
        thread.projectId === projectId &&
        isLive(thread) &&
        thread.lineage.relationshipToParent !== "subagent" &&
        !thread.delegatedFrom,
    )
    .map((thread) => threadRow(host, thread))
    .sort(newestFirst)
    .slice(0, THREAD_LIST_LIMIT);
}

/** T3's runtime mode that asks before each action. */
export const ASK_FIRST = "approval-required";

/** The providers on a host that can start a thread now, leaving out legacy models. */
export function agentProviders(host: T3Host): AgentProvider[] {
  return (host.serverConfig?.providers ?? [])
    .filter(
      (provider) =>
        provider.enabled &&
        provider.installed &&
        provider.availability !== "unavailable" &&
        (provider.status === "ready" || provider.status === "warning"),
    )
    .map((provider) => ({
      instanceId: provider.instanceId,
      name: provider.displayName ?? provider.driver,
      canAskFirst: provider.supportedRuntimeModes?.includes(ASK_FIRST) ?? true,
      models: provider.models.filter((model) => !model.isLegacy).map((model) => ({ slug: model.slug, name: model.name })),
    }))
    .filter((provider) => provider.models.length > 0);
}