/**
 * @file MessageList.tsx
 * @description Renders the chronological message stream of a Claude Code
 * transcript: alternating user / assistant rows with collapsible thinking
 * blocks, inline ToolCallBlocks for tool_use / tool_result pairs, and
 * MarkdownContent for prose. Used by ConversationView as the main body of
 * the Conversation tab on the Session detail page. An image the prompt box
 * attached reaches the transcript as its saved path; a user turn shows the
 * image instead (`GET /api/run/drop/:name`). Each assistant turn that changed
 * files ends with Claude Desktop's "Edited N files" card: every file with the
 * lines added and removed (the tool results' `diff`); a click opens the file
 * when the caller can (`onOpenFile`). A thinking block that carries text is
 * the model's narration to the user (Claude Code ≥ 2.1.280 stores real
 * thinking empty) and reads as prose, like Claude Desktop shows it; a live
 * chat (`live`) ends, until its turn is over, with what the model is doing
 * now — the call still running, else "Thinking…" — and for how long.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */
/* =============================================================================
 * MODULE_GUIDE — extended in-file reference (comments only; safe to read, never executed)
 * =============================================================================
 * **Purpose:** Renders Claude transcript rows (user, assistant, tool calls) inside Session Detail with markdown, syntax highlighting, and TUI-style segments.
 *
 * ## Design constraints
 * - Local-first: no telemetry leaves the machine unless the user configures webhooks.
 * - Fail-safe hooks path on the server must never block Claude Code; UI mirrors that
 *   philosophy by degrading gracefully (empty states, stale badges, reconnect loops).
 * - Destructive flows stay behind explicit confirmation modals and server-side gates.
 * - Internationalization: user-visible strings belong in i18n JSON, not literals here.
 *
 * ## Remote data & SSH
 * Remote Data Sources let operators aggregate multiple machines. SSH entries describe
 * how to reach a peer dashboard; the global data scope (`dataScope.ts`) narrows every
 * scoped GET via `?sources=`. Health checks and import history surface in Settings.
 *
 * ## Internal dependencies
 * - `../../lib/types`
 * - `./ToolCallBlock`
 * - `./MarkdownContent`
 * - `../../lib/format`
 * - `./tuiSegments`
 *
 * ## Public surface
 * - `MessageList` — exported API; see TSDoc on the symbol for behavior.
 *
 * ## Testing pointers
 * - Prefer colocated `__tests__` with Vitest + Testing Library for UI.
 * - Server contract changes require `npm run test:server` and OpenAPI sync.
 *
 * ## Related docs
 * - `ARCHITECTURE.md` — hooks → API → SQLite → WebSocket → UI pipeline.
 * - `docs/API.md` — REST reference.
 * - `skills/file-headers/` — mandatory `@author` header policy.
 * ============================================================================= */
/* -----------------------------------------------------------------------------
 * EXPORT CATALOG — quick index of symbols defined below (documentation only).
 * -----------------------------------------------------------------------------
 * **MessageList**
 *   Part of this module's public contract. Downstream imports should treat
 *   the signature and return type as stable unless release notes say otherwise.
 *   When behavior changes, update the `@file` overview and relevant tests.
 *
 * ----------------------------------------------------------------------------- */

import { memo, useEffect, useState, useMemo } from "react";
import { ImageLightbox } from "../ImageLightbox";
import { useTranslation } from "react-i18next";
import i18n from "../../i18n";
import {
  ChevronDown,
  ChevronRight,
  Bot,
  User,
  Brain,
  ScrollText,
  Terminal,
  Info,
  AlertTriangle,
  Pencil,
  Workflow,
  Cog,
  FileText,
  Loader2,
} from "lucide-react";
import type { TranscriptMessage, TranscriptContent, TranscriptSender } from "../../lib/types";

/** Per-sender visual treatment for a transcript row. A JSONL `type:"user"` line
 *  is not always the human (tool results, harness task-notifications, the
 *  orchestrator's task to a subagent) — each sender gets its own label, icon,
 *  and accent so attribution is unambiguous. */
const SENDER_STYLES: Record<
  TranscriptSender,
  { icon: typeof User; avatarRing: string; accentBar: string; headerText: string }
> = {
  user: {
    icon: User,
    avatarRing: "bg-syntax-builtin/15 text-syntax-builtin ring-1 ring-syntax-builtin/30",
    accentBar: "before:bg-syntax-builtin/40",
    headerText: "text-syntax-builtin",
  },
  assistant: {
    icon: Bot,
    avatarRing: "bg-syntax-keyword/15 text-syntax-keyword ring-1 ring-syntax-keyword/30",
    accentBar: "before:bg-syntax-keyword/40",
    headerText: "text-syntax-keyword",
  },
  orchestrator: {
    icon: Workflow,
    avatarRing: "bg-syntax-string/15 text-syntax-string ring-1 ring-syntax-string/30",
    accentBar: "before:bg-syntax-string/40",
    headerText: "text-syntax-string",
  },
  system: {
    icon: Cog,
    avatarRing: "bg-surface-4 text-fg-secondary ring-1 ring-border-light/30",
    accentBar: "before:bg-surface-4/40",
    headerText: "text-fg-secondary",
  },
  tool: {
    icon: Terminal,
    avatarRing: "bg-status-warning/15 text-status-warning ring-1 ring-status-warning/30",
    accentBar: "before:bg-status-warning/40",
    headerText: "text-status-warning",
  },
};
import { ToolCallBlock, buildSummary, renderInput, renderResult } from "./ToolCallBlock";
import { MarkdownContent } from "./MarkdownContent";
import { fmt, formatModelName, formatMs, parseDate } from "../../lib/format";
import { parseTuiSegments, stripAnsi, hasTuiTags, type TuiSegment } from "./tuiSegments";

interface MessageListProps {
  messages: TranscriptMessage[];
  loading: boolean;
  /** Opens a file named in the "Edited N files" card. */
  onOpenFile?: (path: string) => void;
  /** The session is running in a pane: show the step in progress. */
  live?: boolean;
}

/** Build a map from tool_use id → tool_result for matching */
function buildToolResultMap(messages: TranscriptMessage[]): Map<string, TranscriptContent> {
  const map = new Map<string, TranscriptContent>();
  for (const msg of messages) {
    if (msg.type !== "user") continue;
    for (const c of msg.content) {
      if (c.type === "tool_result" && c.id) {
        map.set(c.id, c);
      }
    }
  }
  return map;
}

/** The whole prompt a message was answered from: `input_tokens` is only its
 *  uncached tail (a few tokens once the cache is warm), the rest is cache. */
function promptTokens(u: NonNullable<TranscriptMessage["usage"]>): number {
  return (
    (u.input_tokens || 0) + (u.cache_read_input_tokens || 0) + (u.cache_creation_input_tokens || 0)
  );
}
const usageTitle = (u: NonNullable<TranscriptMessage["usage"]>) =>
  `input ${fmt(u.input_tokens || 0)} · cache read ${fmt(u.cache_read_input_tokens || 0)} · cache write ${fmt(u.cache_creation_input_tokens || 0)} · output ${fmt(u.output_tokens || 0)}`;

/** Detect if text is skill loading content (starts with "Base directory for this skill:") */
function isSkillContent(text: string): boolean {
  return text.startsWith("Base directory for this skill:");
}

/** Detect if text is a task notification (contains <task-notification> tag) */
function isTaskNotification(text: string): boolean {
  return text.includes("<task-notification>") || text.includes("<task-id>");
}

/** Format a timestamp as compact local time (e.g. "14:23:01"). */
function formatLocalTime(iso: string): string {
  try {
    return new Date(iso).toLocaleTimeString();
  } catch {
    return "";
  }
}

/** Centered marker for a session rename (/rename, `claude -n`, picker Ctrl+R).
 *  These TUI-only commands write no conversation turn, so without this they're
 *  invisible in the transcript. */
function SessionEventRow({ title, timestamp }: { title?: string; timestamp: string | null }) {
  return (
    <div className="flex items-center justify-center py-1">
      <div className="inline-flex items-center gap-2 text-[11px] text-fg-secondary bg-surface-2/70 border border-surface-3 rounded-full px-3 py-1 max-w-full">
        <Pencil className="w-3 h-3 text-violet-700/70 dark:text-violet-300/70 flex-shrink-0" />
        <span className="text-fg-muted">Renamed session →</span>
        <span className="text-fg-secondary font-medium truncate">{title || "(untitled)"}</span>
        {timestamp && (
          <span className="text-[10px] text-fg-muted font-mono flex-shrink-0">
            {formatLocalTime(timestamp)}
          </span>
        )}
      </div>
    </div>
  );
}

/** Compact pill for /command invocations parsed out of TUI markup. */
function CommandPill({ display }: { display: string }) {
  return (
    <div className="inline-flex items-center gap-2 text-sm text-status-success font-mono bg-status-success/10 border border-status-success/20 rounded-md px-3 py-1.5 max-w-full">
      <span className="text-status-success/70">›</span>
      <span className="break-all">{display}</span>
    </div>
  );
}

/** Terminal-style fenced block for stdout/stderr captured from local commands. */
function TerminalBlock({ text, stream }: { text: string; stream: "stdout" | "stderr" }) {
  const cleaned = stripAnsi(text).replace(/^\n+|\n+$/g, "");
  const isErr = stream === "stderr";
  const accent = isErr
    ? "border-status-danger/30 bg-status-danger/30 text-status-danger/90"
    : "border-surface-3 bg-surface-4/60 text-fg-secondary";
  const labelColor = isErr ? "text-status-danger/80" : "text-fg-secondary";
  return (
    <div className={`rounded-lg border ${accent} overflow-hidden`}>
      <div
        className={`flex items-center gap-1.5 px-3 py-1 text-[10px] uppercase tracking-wider border-b border-current/10 ${labelColor}`}
      >
        <Terminal className="w-3 h-3" />
        <span>{stream}</span>
      </div>
      <pre className="px-3 py-2 text-xs font-mono whitespace-pre-wrap break-words leading-relaxed max-h-96 overflow-y-auto">
        {cleaned}
      </pre>
    </div>
  );
}

/** Subtle inline note for the local-command-caveat banner. */
function CaveatBlock({ text }: { text: string }) {
  return (
    <div className="flex items-start gap-2 rounded-md border border-status-warning/15 bg-status-warning/[0.05] px-3 py-1.5 text-[11px] text-status-warning/70">
      <Info className="w-3.5 h-3.5 mt-px flex-shrink-0 opacity-60" />
      <span className="leading-relaxed italic">{stripAnsi(text).trim()}</span>
    </div>
  );
}

/** Render a single segment produced by parseTuiSegments. */
function renderSegment(seg: TuiSegment, key: number): React.ReactNode {
  switch (seg.kind) {
    case "command":
      return <CommandPill key={key} display={seg.display} />;
    case "stdout":
      return <TerminalBlock key={key} text={seg.text} stream="stdout" />;
    case "stderr":
      return <TerminalBlock key={key} text={seg.text} stream="stderr" />;
    case "caveat":
      return <CaveatBlock key={key} text={seg.text} />;
    case "system-reminder":
      return (
        <CollapsibleBlock
          key={key}
          text={seg.text}
          icon={<AlertTriangle className="w-3.5 h-3.5 text-status-warning/70 flex-shrink-0" />}
          title={i18n.t("sessions:conversation.systemReminder")}
          borderClass="border-status-warning/20"
          bgClass="bg-status-warning/5"
          textClass="text-status-warning/80"
        />
      );
    case "persisted-output":
      return (
        <CollapsibleBlock
          key={key}
          text={seg.text}
          icon={<ScrollText className="w-3.5 h-3.5 text-syntax-keyword/70 flex-shrink-0" />}
          title={i18n.t("sessions:conversation.persistedOutput")}
          borderClass="border-syntax-keyword/20"
          bgClass="bg-syntax-keyword/5"
          textClass="text-syntax-keyword"
        />
      );
    case "text": {
      const cleaned = stripAnsi(seg.text);
      if (!cleaned.trim()) return null;
      return (
        <div key={key} className="min-w-0">
          <MarkdownContent text={cleaned} />
        </div>
      );
    }
  }
}

/** A text block of any sender: a task notification or skill body collapsed,
 *  TUI markup as segments, anything else as markdown. */
function renderTextBlock(text: string, key: number): React.ReactNode {
  // Detect task notifications, collapsed by default
  if (isTaskNotification(text)) {
    return (
      <CollapsibleBlock
        key={key}
        text={text}
        icon={<ScrollText className="w-3.5 h-3.5 text-syntax-property/70 flex-shrink-0" />}
        title={i18n.t("sessions:conversation.taskNotification")}
        borderClass="border-syntax-property/20"
        bgClass="bg-syntax-property/5"
        textClass="text-syntax-property"
      />
    );
  }

  // Detect skill content, collapsed by default
  if (isSkillContent(text)) {
    const pathMatch = text.match(/^Base directory for this skill:\s*(\S+)/);
    const skillPath = pathMatch ? pathMatch[1]! : "Skill";
    return (
      <CollapsibleBlock
        key={key}
        text={text}
        icon={<ScrollText className="w-3.5 h-3.5 text-syntax-builtin/70 flex-shrink-0" />}
        title={skillPath}
        borderClass="border-syntax-builtin/20"
        bgClass="bg-syntax-builtin/5"
        textClass="text-syntax-builtin"
      />
    );
  }

  // Mixed TUI markup: caveat / command / stdout / stderr / system-reminder
  // can appear inline (sometimes interleaved with prose). Parse the text
  // into segments and render each with the appropriate visual treatment.
  if (hasTuiTags(text)) {
    const segments = parseTuiSegments(text);
    return (
      <div key={key} className="space-y-2 min-w-0">
        {segments.map((s, sIdx) => renderSegment(s, sIdx))}
      </div>
    );
  }

  return (
    <div key={key} className="min-w-0">
      <MarkdownContent text={stripAnsi(text)} />
    </div>
  );
}

/** Generic collapsible content block */
function CollapsibleBlock({
  text,
  icon,
  title,
  borderClass,
  bgClass,
  textClass,
}: {
  text: string;
  icon: React.ReactNode;
  title: string;
  borderClass: string;
  bgClass: string;
  textClass: string;
}) {
  const [expanded, setExpanded] = useState(false);

  return (
    <div className={`rounded-lg border ${borderClass} ${bgClass} overflow-hidden`}>
      <button
        onClick={() => setExpanded(!expanded)}
        aria-expanded={expanded}
        className="w-full flex items-center gap-2 px-3 py-1.5 text-left hover:opacity-80 transition-colors"
      >
        {expanded ? (
          <ChevronDown className="w-3.5 h-3.5 opacity-60 flex-shrink-0" />
        ) : (
          <ChevronRight className="w-3.5 h-3.5 opacity-60 flex-shrink-0" />
        )}
        {icon}
        <span className={`text-xs ${textClass} truncate`}>{title}</span>
      </button>
      {expanded && (
        <div className="border-t border-current/10 px-3 py-2">
          <pre className="text-xs opacity-60 whitespace-pre-wrap break-words leading-relaxed max-h-96 overflow-y-auto">
            {text}
          </pre>
        </div>
      )}
    </div>
  );
}

/** A key per message that survives prepend (older history) and append (live
 *  tail): built from the message itself, with an occurrence counter for twins.
 *  The index was the key before, so expanding a block and then loading older
 *  messages moved the expansion onto another message. */
export function messageKeys(messages: TranscriptMessage[]): string[] {
  const seen = new Map<string, number>();
  return messages.map((m) => {
    const first = m.content[0];
    const sig = first
      ? `${first.type}:${first.id ?? (first.text ?? "").slice(0, 48)}`
      : (m.title ?? "");
    const base = `${m.timestamp ?? ""}|${m.type}|${m.sender ?? ""}|${sig}`;
    const n = seen.get(base) ?? 0;
    seen.set(base, n + 1);
    return n ? `${base}#${n}` : base;
  });
}

/** One thing on screen, in the Claude Desktop layout: a human message as a
 *  bubble, the assistant's prose bare, and everything it did between two
 *  pieces of prose — tool calls and thinking, across messages (Claude Code
 *  writes each as its own line) — as ONE collapsed line; any other sender
 *  keeps its attributed row. */
type Item =
  | { kind: "event"; key: string; msg: TranscriptMessage }
  | { kind: "row"; key: string; msg: TranscriptMessage }
  | { kind: "user"; key: string; msg: TranscriptMessage }
  | { kind: "text"; key: string; msg: TranscriptMessage; text: string }
  | { kind: "work"; key: string; blocks: TranscriptContent[] }
  | { kind: "edits"; key: string; blocks: TranscriptContent[] };

const EDIT_TOOLS = new Set(["Write", "Edit", "MultiEdit", "NotebookEdit"]);

export function chatItems(messages: TranscriptMessage[], keys: string[]): Item[] {
  const items: Item[] = [];
  // The file-changing calls of the turn so far, closed into one card when the
  // human speaks again (or the list ends).
  let edits: TranscriptContent[] = [];
  const endTurn = (key: string) => {
    if (edits.length) items.push({ kind: "edits", key: `edits:${key}`, blocks: edits });
    edits = [];
  };
  messages.forEach((msg, idx) => {
    const key = keys[idx]!;
    if (msg.type === "session_event") return items.push({ kind: "event", key, msg });
    // Purely tool_result: shown inside its call's block.
    if (msg.type === "user" && !msg.content.some((c) => c.type === "text")) return;
    const sender = msg.sender ?? (msg.type === "assistant" ? "assistant" : "user");
    if (sender === "user") {
      endTurn(key);
      return items.push({ kind: "user", key, msg });
    }
    if (sender !== "assistant") return items.push({ kind: "row", key, msg });
    msg.content.forEach((block, b) => {
      const last = items[items.length - 1];
      if (block.type === "tool_use" && EDIT_TOOLS.has(block.name ?? "")) edits.push(block);
      if (block.type === "tool_use") {
        if (last?.kind === "work") last.blocks.push(block);
        else items.push({ kind: "work", key: `${key}:${b}`, blocks: [block] });
      } else if ((block.type === "text" || block.type === "thinking") && block.text?.trim()) {
        items.push({ kind: "text", key: `${key}:${b}`, msg, text: block.text });
      }
    });
  });
  endTurn(keys[keys.length - 1] ?? "end");
  return items;
}

/** Claude Desktop's end-of-turn card: the files the turn changed, each with
 *  the lines added and removed. A call still running or failed is left out. */
function EditedFiles({
  blocks,
  toolResultMap,
  onOpenFile,
}: {
  blocks: TranscriptContent[];
  toolResultMap: Map<string, TranscriptContent>;
  onOpenFile?: (path: string) => void;
}) {
  const { t } = useTranslation("sessions");
  // `counted`: a result carried its +/- lines (an older server sends none).
  const files = new Map<string, { added: number; removed: number; counted: boolean }>();
  for (const b of blocks) {
    const input = (b.input ?? {}) as Record<string, unknown>;
    const p = input.file_path ?? input.notebook_path;
    const r = b.id ? toolResultMap.get(b.id) : undefined;
    if (typeof p !== "string" || !r || r.is_error) continue;
    const f = files.get(p) ?? { added: 0, removed: 0, counted: false };
    f.added += r.diff?.added ?? 0;
    f.removed += r.diff?.removed ?? 0;
    f.counted ||= !!r.diff;
    files.set(p, f);
  }
  if (files.size === 0) return null;
  let added = 0;
  let removed = 0;
  let counted = false;
  files.forEach((f) => {
    added += f.added;
    removed += f.removed;
    counted ||= f.counted;
  });
  const counts = (a: number, r: number, show = counted) =>
    show && (
      <span className="flex-shrink-0 font-mono text-xs">
        <span className="text-status-success">+{a}</span>{" "}
        <span className="text-status-danger">−{r}</span>
      </span>
    );
  return (
    <div data-testid="edited-files" className="overflow-hidden rounded-xl border border-border">
      <div className="flex items-center gap-2 border-b border-border bg-surface-1 px-3 py-2 text-sm text-fg-primary">
        <Pencil className="h-3.5 w-3.5 text-fg-muted" />
        <span className="flex-1">{t("conversation.edited", { count: files.size })}</span>
        {counts(added, removed)}
      </div>
      {[...files].map(([p, f]) => (
        <button
          key={p}
          type="button"
          title={p}
          disabled={!onOpenFile}
          onClick={() => onOpenFile?.(p)}
          className="flex w-full items-center gap-2 border-b border-border px-3 py-2 text-left text-sm text-fg-secondary last:border-b-0 enabled:hover:bg-surface-2"
        >
          <FileText className="h-3.5 w-3.5 flex-shrink-0 text-fg-muted" />
          <span className="min-w-0 flex-1 truncate">{p.split("/").pop()}</span>
          {counts(f.added, f.removed, f.counted)}
          {onOpenFile && <ChevronRight className="h-3.5 w-3.5 flex-shrink-0 text-fg-muted" />}
        </button>
      ))}
    </div>
  );
}

export function MessageList({ messages, loading, onOpenFile, live = false }: MessageListProps) {
  const { t } = useTranslation("sessions");
  const toolResultMap = useMemo(() => buildToolResultMap(messages), [messages]);
  const pending = useMemo(
    () => (live ? workingOn(messages, toolResultMap) : null),
    [live, messages, toolResultMap]
  );
  const keys = useMemo(() => messageKeys(messages), [messages]);
  const items = useMemo(() => chatItems(messages, keys), [messages, keys]);

  if (loading) {
    return (
      <div className="flex items-center justify-center py-12 text-fg-muted text-sm">
        {t("conversation.loading")}
      </div>
    );
  }

  if (messages.length === 0) {
    return <div className="text-center py-12 text-fg-muted text-sm">{t("conversation.empty")}</div>;
  }

  return (
    <div className="mx-auto w-full max-w-[max(48rem,70%)] space-y-4 px-4 py-4">
      {items.map((item) => {
        switch (item.kind) {
          case "event":
            return (
              <SessionEventRow
                key={item.key}
                title={item.msg.title}
                timestamp={item.msg.timestamp}
              />
            );
          case "row":
            return <MessageRow key={item.key} msg={item.msg} toolResultMap={toolResultMap} />;
          case "user":
            return <UserBubble key={item.key} msg={item.msg} />;
          case "text":
            return <AssistantText key={item.key} msg={item.msg} text={item.text} />;
          case "work":
            return <WorkGroup key={item.key} blocks={item.blocks} toolResultMap={toolResultMap} />;
          case "edits":
            // The card closes a finished turn; one still working has none yet.
            if (pending && item === items[items.length - 1]) return null;
            return (
              <EditedFiles
                key={item.key}
                blocks={item.blocks}
                toolResultMap={toolResultMap}
                onOpenFile={onOpenFile}
              />
            );
        }
      })}
      {pending && <RunningStep block={pending.block} since={pending.since} />}
    </div>
  );
}

// No line for this long and no call running: the turn died with no end
// written (a crash, a kill) — stop saying it works.
const IDLE_AFTER_MS = 15 * 60_000;

/** What the model is doing while its turn is not over: the call still
 *  waiting for its result (`block`), else thinking (`block: null`); `since`
 *  is that line's time. Null once the turn ended. */
export function workingOn(
  messages: TranscriptMessage[],
  results: Map<string, TranscriptContent>,
  now = Date.now()
): { block: TranscriptContent | null; since: string | null } | null {
  for (let i = messages.length - 1; i >= 0; i--) {
    const msg = messages[i]!;
    const sender = msg.sender ?? (msg.type === "assistant" ? "assistant" : "user");
    // A rename marker or a harness line says nothing about the turn.
    if (msg.type === "session_event" || sender === "system" || sender === "orchestrator") continue;
    const since = msg.timestamp ?? null;
    const fresh = !since || now - parseDate(since).getTime() < IDLE_AFTER_MS;
    if (msg.type === "assistant") {
      const call = [...msg.content].reverse().find((b) => b.type === "tool_use");
      if (call?.id && !results.has(call.id)) return { block: call, since };
      // "tool_use": a call follows. "end_turn" (or none, from an older server): over.
      return msg.stop_reason === "tool_use" && fresh ? { block: null, since } : null;
    }
    // A prompt or a tool result: the model answers it next — unless the user stopped it.
    const text = msg.content.find((c) => c.type === "text")?.text ?? "";
    if (text.startsWith("[Request interrupted")) return null;
    return fresh ? { block: null, since } : null;
  }
  return null;
}

/** Claude Desktop's live line: the step running now and for how long. */
function RunningStep({ block, since }: { block: TranscriptContent | null; since: string | null }) {
  const { t } = useTranslation("sessions");
  const [now, setNow] = useState(() => Date.now());
  useEffect(() => {
    const timer = window.setInterval(() => setNow(Date.now()), 1000);
    return () => window.clearInterval(timer);
  }, []);
  const input = block?.input as Record<string, unknown> | undefined;
  const title = !block
    ? t("conversation.working")
    : typeof input?.description === "string" && input.description
      ? input.description
      : [block.name, buildSummary(block)].filter(Boolean).join(" ");
  return (
    <div data-testid="chat-running-step" className="flex items-center gap-2 text-sm text-fg-muted">
      <Loader2 className="h-3.5 w-3.5 flex-shrink-0 animate-spin text-accent" />
      <span className="min-w-0 truncate">{title}</span>
      {since && (
        <span className="flex-shrink-0 font-mono text-xs">
          {formatMs(now - parseDate(since).getTime())}
        </span>
      )}
    </div>
  );
}

const meta = "text-[10px] font-mono text-fg-muted";

// What the prompt box sends for an attached image: its saved path under the
// drop dir (`<tmp>/agenthub-drops-<uid>/<16 hex>[-name].png`, server/routes/run.js).
const DROP_IMAGE =
  /(?<=^|\s)\S*[\\/]agenthub-drops--?\d+[\\/]([0-9a-f]{16}(?:-[A-Za-z0-9._-]+)?\.(?:png|jpe?g|gif|webp))(?=\s|$)/gi;

/** A user turn's text without its dropped-image paths, and those images' names. */
export function splitDropImages(text: string): { text: string; images: string[] } {
  const images: string[] = [];
  const rest = text.replace(DROP_IMAGE, (_all, name: string) => {
    images.push(name);
    return "";
  });
  return { text: images.length ? rest.replace(/[ \t]+$/gm, "").trim() : text, images };
}

function DropImage({ name }: { name: string }) {
  const [open, setOpen] = useState(false);
  const [gone, setGone] = useState(false);
  const src = `/api/run/drop/${encodeURIComponent(name)}`;
  // Drops are pruned after a day: the name is all that is left to show.
  if (gone)
    return (
      <span className="flex items-center gap-1.5 rounded-lg border border-border bg-surface-2 px-2 py-1 text-xs text-fg-muted">
        <FileText className="h-3.5 w-3.5 shrink-0" />
        <span className="truncate">{name.replace(/^[0-9a-f]{16}-?/, "") || name}</span>
      </span>
    );
  return (
    <>
      <button
        type="button"
        onClick={() => setOpen(true)}
        className="block overflow-hidden rounded-xl border border-border bg-surface-2 hover:border-accent/50"
      >
        <img
          src={src}
          alt={name}
          loading="lazy"
          onError={() => setGone(true)}
          className="max-h-48 max-w-64 object-contain"
        />
      </button>
      {open && <ImageLightbox src={src} alt={name} onClose={() => setOpen(false)} />}
    </>
  );
}

/** The human's turn: a bubble on the right, its time on hover. A long one (a
 *  paste, a compaction summary) shows its first lines until opened. */
const LONG_BUBBLE = 800;
const UserBubble = memo(function UserBubble({ msg }: { msg: TranscriptMessage }) {
  const { t } = useTranslation("sessions");
  const long = msg.content.reduce((n, c) => n + (c.text?.length ?? 0), 0) > LONG_BUBBLE;
  const [open, setOpen] = useState(false);
  const blocks = useMemo(
    () =>
      msg.content.map((block) =>
        block.type === "text" && block.text ? splitDropImages(block.text) : null
      ),
    [msg.content]
  );
  const images = blocks.flatMap((b) => b?.images ?? []);
  const hasText = blocks.some((b) => b?.text);
  return (
    <div
      data-testid="chat-user"
      style={{ contentVisibility: "auto", containIntrinsicSize: "auto 60px" }}
      className="group flex flex-col items-end gap-1"
    >
      {images.length > 0 && (
        <div
          data-testid="chat-user-images"
          className="flex max-w-[85%] flex-wrap justify-end gap-2"
        >
          {images.map((name) => (
            <DropImage key={name} name={name} />
          ))}
        </div>
      )}
      {hasText && (
        <div
          className={`max-w-[85%] min-w-0 space-y-2 rounded-2xl bg-surface-2 px-4 py-2.5 text-sm text-fg-primary ${
            long && !open
              ? "max-h-40 overflow-hidden [mask-image:linear-gradient(to_bottom,black_60%,transparent)]"
              : ""
          }`}
        >
          {blocks.map((block, b) => {
            const text = block?.text;
            if (!text) return null;
            // Plain typing reads as typed; anything structured keeps its rendering.
            const plain = !hasTuiTags(text) && !isSkillContent(text) && !isTaskNotification(text);
            return plain ? (
              <p key={b} className="whitespace-pre-wrap break-words leading-relaxed">
                {stripAnsi(text).trim()}
              </p>
            ) : (
              renderTextBlock(text, b)
            );
          })}
        </div>
      )}
      {long && (
        <button
          type="button"
          aria-expanded={open}
          onClick={() => setOpen(!open)}
          className="text-xs text-fg-muted hover:text-fg-secondary"
        >
          {open ? t("conversation.showLess") : t("conversation.showMore")}
        </button>
      )}
      {msg.timestamp && (
        <span className={`${meta} opacity-0 transition-opacity group-hover:opacity-100`}>
          {formatLocalTime(msg.timestamp)}
        </span>
      )}
    </div>
  );
});

/** The assistant's prose, bare on the page; model, tokens and time on hover. */
const AssistantText = memo(function AssistantText({
  msg,
  text,
}: {
  msg: TranscriptMessage;
  text: string;
}) {
  return (
    <div
      data-testid="chat-assistant"
      style={{ contentVisibility: "auto", containIntrinsicSize: "auto 120px" }}
      className="group min-w-0"
    >
      {hasTuiTags(text) || isSkillContent(text) || isTaskNotification(text) ? (
        renderTextBlock(text, 0)
      ) : (
        <MarkdownContent text={stripAnsi(text)} prose />
      )}
      <div
        className={`${meta} mt-1 flex gap-2 opacity-0 transition-opacity group-hover:opacity-100`}
      >
        {msg.model && <span>{formatModelName(msg.model)}</span>}
        {msg.usage && (
          <span title={usageTitle(msg.usage)}>
            ↓ {fmt(promptTokens(msg.usage))} · ↑ {fmt(msg.usage.output_tokens)}
          </span>
        )}
        {msg.timestamp && <span>{formatLocalTime(msg.timestamp)}</span>}
      </div>
    </div>
  );
});

/** A muted line that opens to show what it stands for. */
function Disclosure({ label, children }: { label: string; children: React.ReactNode }) {
  const [open, setOpen] = useState(false);
  return (
    <div>
      <button
        type="button"
        aria-expanded={open}
        onClick={() => setOpen(!open)}
        className="inline-flex items-center gap-1 text-sm text-fg-muted transition-colors hover:text-fg-secondary"
      >
        {label}
        <ChevronRight className={`h-3.5 w-3.5 transition-transform ${open ? "rotate-90" : ""}`} />
      </button>
      {open && <div className="mt-2 space-y-2">{children}</div>}
    </div>
  );
}

/** The kind of work a tool call is, for the group's label (Claude Code and
 *  Codex names); anything else counts as a tool. */
const WORK_KIND: Record<string, string> = {
  bash: "commands",
  shell: "commands",
  exec_command: "commands",
  powershell: "commands",
  edit: "edits",
  multiedit: "edits",
  write: "edits",
  notebookedit: "edits",
  apply_patch: "edits",
  read: "reads",
  grep: "searches",
  glob: "searches",
  ls: "searches",
  websearch: "web",
  webfetch: "web",
  task: "agents",
  agent: "agents",
};

/** "Ran 3 commands, edited 2 files" — or "Thinking" when it only thought. */
const KIND_ORDER = ["commands", "edits", "reads", "searches", "web", "agents", "tools"];

export function workLabel(blocks: TranscriptContent[]): string {
  const counts = new Map<string, number>();
  for (const b of blocks) {
    if (b.type !== "tool_use") continue;
    const kind = WORK_KIND[(b.name ?? "").toLowerCase()] ?? "tools";
    counts.set(kind, (counts.get(kind) ?? 0) + 1);
  }
  if (!counts.size) return i18n.t("sessions:conversation.thinking");
  // Claude Desktop's order: commands, edits, reads, … and other tools last.
  const text = [...counts]
    .sort(([a], [b]) => KIND_ORDER.indexOf(a) - KIND_ORDER.indexOf(b))
    .map(([kind, count]) => i18n.t(`sessions:conversation.work.${kind}`, { count }))
    .join(", ");
  return text.charAt(0).toUpperCase() + text.slice(1);
}

/** One step inside an opened group, as Claude Desktop lists them: its own
 *  description (Claude Code's Bash `description`) or the tool and target as
 *  the title, the call itself under it in a capped scroll box, the result one
 *  click further. Thinking is a step too, closed. */
function WorkStep({
  block,
  result,
}: {
  block: TranscriptContent;
  result: TranscriptContent | null;
}) {
  const { t } = useTranslation("sessions");
  const thinking = block.type === "thinking";
  const [open, setOpen] = useState(!thinking);
  const [showResult, setShowResult] = useState(false);
  const input = block.input as Record<string, unknown> | undefined;
  const title = thinking
    ? t("conversation.thinking")
    : typeof input?.description === "string" && input.description
      ? input.description
      : [block.name, buildSummary(block)].filter(Boolean).join(" ");
  return (
    <div className="px-3 py-2">
      <button
        type="button"
        aria-expanded={open}
        onClick={() => setOpen(!open)}
        className={`flex w-full min-w-0 items-center gap-1 text-left text-sm transition-colors hover:text-fg-secondary ${
          result?.is_error ? "text-status-danger" : "text-fg-muted"
        }`}
      >
        <span className="truncate">{title}</span>
        <ChevronDown
          className={`h-3.5 w-3.5 shrink-0 transition-transform ${open ? "" : "-rotate-90"}`}
        />
      </button>
      {open && (
        <div className="mt-2 space-y-2">
          {thinking ? (
            <div className="max-h-60 overflow-auto text-fg-muted">
              <MarkdownContent text={block.text ?? ""} dense />
            </div>
          ) : (
            <>
              <div className="max-h-60 overflow-auto">
                {/* The description is the title already. */}
                {renderInput(
                  input ? { ...block, input: { ...input, description: undefined } } : block
                )}
              </div>
              {result && (
                <button
                  type="button"
                  aria-expanded={showResult}
                  onClick={() => setShowResult(!showResult)}
                  className="inline-flex items-center gap-1 text-xs text-fg-muted hover:text-fg-secondary"
                >
                  {result.is_error ? t("conversation.tool.error") : t("conversation.tool.output")}
                  <ChevronRight
                    className={`h-3 w-3 transition-transform ${showResult ? "rotate-90" : ""}`}
                  />
                </button>
              )}
              {result && showResult && (
                <div className="max-h-60 overflow-auto">
                  {renderResult(result, block.name ?? "")}
                </div>
              )}
            </>
          )}
        </div>
      )}
    </div>
  );
}

/** What the assistant did between two replies as one line, opening onto
 *  one framed list of its steps. */
const WorkGroup = memo(function WorkGroup({
  blocks,
  toolResultMap,
}: {
  blocks: TranscriptContent[];
  toolResultMap: ReturnType<typeof buildToolResultMap>;
}) {
  return (
    <div data-testid="chat-tools">
      <Disclosure label={workLabel(blocks)}>
        <div className="divide-y divide-border overflow-hidden rounded-xl border border-border">
          {blocks.map((block, i) => (
            <WorkStep
              key={block.id ?? i}
              block={block}
              result={block.id ? (toolResultMap.get(block.id) ?? null) : null}
            />
          ))}
        </div>
      </Disclosure>
    </div>
  );
});

/** One user/assistant row. Memoized: a live tail append re-renders only the
 *  new rows; its thinking-block expansion is its own state, kept by key. */
const MessageRow = memo(function MessageRow({
  msg,
  toolResultMap,
}: {
  msg: TranscriptMessage;
  toolResultMap: ReturnType<typeof buildToolResultMap>;
}) {
  const { t } = useTranslation("sessions");
  const [expandedThinking, setExpandedThinking] = useState<Set<number>>(() => new Set());
  const isAssistant = msg.type === "assistant";
  // The true sender (classified server-side) drives the label + styling.
  // Falls back to the coarse type for older payloads without `sender`.
  const sender: TranscriptSender = msg.sender ?? (isAssistant ? "assistant" : "user");
  const style = SENDER_STYLES[sender] ?? SENDER_STYLES.user;
  const SenderIcon = style.icon;

  return (
    <div
      style={{ contentVisibility: "auto", containIntrinsicSize: "auto 120px" }}
      className={`relative flex gap-3 rounded-xl px-3 py-2.5 hover:bg-surface-2/30 transition-colors before:absolute before:left-0 before:top-3 before:bottom-3 before:w-0.5 before:rounded-full before:opacity-60 ${style.accentBar}`}
    >
      {/* Avatar */}
      <div
        className={`flex-shrink-0 w-8 h-8 rounded-full flex items-center justify-center mt-0.5 shadow-sm ${style.avatarRing}`}
      >
        <SenderIcon className="w-4 h-4" />
      </div>

      {/* Message body */}
      <div className="flex-1 min-w-0 space-y-2">
        {/* Header line */}
        <div className="flex items-center gap-2 flex-wrap">
          <span className={`text-xs font-semibold tracking-wide ${style.headerText}`}>
            {t(`conversation.sender.${sender}`)}
          </span>
          {msg.model && (
            <span className="text-[10px] text-fg-secondary font-mono bg-surface-3/60 border border-surface-3 rounded px-1.5 py-0.5">
              {formatModelName(msg.model)}
            </span>
          )}
          {msg.usage && (
            <span
              title={usageTitle(msg.usage)}
              className="text-[10px] text-fg-muted font-mono inline-flex items-center gap-1"
            >
              <span className="text-status-success/70">↓ {fmt(promptTokens(msg.usage))}</span>
              <span className="text-fg-muted">·</span>
              <span className="text-syntax-number">↑ {fmt(msg.usage.output_tokens)}</span>
            </span>
          )}
          {msg.timestamp && (
            <span className="text-[10px] text-fg-muted ml-auto font-mono">
              {formatLocalTime(msg.timestamp)}
            </span>
          )}
        </div>

        {/* Content blocks */}
        {msg.content.map((block, bIdx) => {
          if (block.type === "text" && block.text) return renderTextBlock(block.text, bIdx);

          if (block.type === "thinking" && block.text) {
            const thinkKey = bIdx;
            const isExpanded = expandedThinking.has(thinkKey);
            return (
              <div
                key={bIdx}
                className="rounded-lg border border-status-warning/20 bg-status-warning/5 overflow-hidden"
              >
                <button
                  aria-expanded={isExpanded}
                  onClick={() =>
                    setExpandedThinking((prev) => {
                      const next = new Set(prev);
                      if (next.has(thinkKey)) next.delete(thinkKey);
                      else next.add(thinkKey);
                      return next;
                    })
                  }
                  className="w-full flex items-center gap-2 px-3 py-1.5 text-left hover:bg-status-warning/10 transition-colors"
                >
                  <ChevronRight
                    className={`w-3.5 h-3.5 text-status-warning/60 transition-transform duration-150 ${
                      isExpanded ? "rotate-90" : ""
                    }`}
                  />
                  <Brain className="w-3.5 h-3.5 text-status-warning/80" />
                  <span className="text-xs text-status-warning/90 font-medium">
                    {t("conversation.thinking")}
                  </span>
                  {!isExpanded && (
                    <span className="text-[10px] text-status-warning/40 font-mono ml-auto">
                      {t("conversation.chars", {
                        count: block.text.length,
                        formatted: block.text.length.toLocaleString(),
                      })}
                    </span>
                  )}
                </button>
                {isExpanded && (
                  <div className="border-t border-status-warning/10 px-3 py-2 text-status-warning/80">
                    <MarkdownContent text={block.text} dense />
                  </div>
                )}
              </div>
            );
          }

          if (block.type === "tool_use") {
            const matchedResult = block.id ? (toolResultMap.get(block.id) ?? null) : null;
            return <ToolCallBlock key={bIdx} toolUse={block} toolResult={matchedResult} />;
          }

          // tool_result blocks rendered inside ToolCallBlock, skip standalone
          return null;
        })}
      </div>
    </div>
  );
});