feat(ai-chat): copy agent chat as Markdown to clipboard

Add a header button to the AI agent chat window that copies the active
conversation to the clipboard as Markdown, including the request
internals already persisted client-side — tool calls with their
input/output, per-message token usage, and finish/error info. No new
network call and no server/DB change: it serializes the already-loaded
persisted message rows.

- New util chat-markdown.ts (renamed from export-chat.ts): pure
  buildChatMarkdown() serializer reusing the tool-parts helpers so tool
  labels match the on-screen labels; fence() escapes embedded code
  fences.
- ai-chat-window.tsx: Copy button (shown only for a saved chat with
  loaded rows) using the project useClipboard hook; toggles a check
  icon on success and shows the standard "Copied" notification. Drag is
  unaffected (startDrag ignores button clicks).
- en-US: add "Copy chat" key, drop the obsolete "Export chat".

apps/client/public/locales/en-US/translation.json

@@ -253,6 +253,7 @@
   "Invite link": "Invite link",
   "Copy": "Copy",
   "Copy to space": "Copy to space",
+  "Copy chat": "Copy chat",
   "Copied": "Copied",
   "Duplicate": "Duplicate",
   "Select a user": "Select a user",
@@ -947,7 +948,6 @@
   "Try a different search term.": "Try a different search term.",
   "Try again": "Try again",
   "Untitled chat": "Untitled chat",
-  "Export chat": "Export chat",
   "You": "You",
   "What can I help you with?": "What can I help you with?",
   "Are you sure you want to revoke this {{credential}}": "Are you sure you want to revoke this {{credential}}",

apps/client/src/features/ai-chat/components/ai-chat-window.tsx

@@ -9,8 +9,9 @@ import {
 import { Group, Loader, Tooltip } from "@mantine/core";
 import {
   IconArrowsDiagonal,
+  IconCheck,
   IconChevronDown,
-  IconFileExport,
+  IconCopy,
   IconGripVertical,
   IconMinus,
   IconPlus,
@@ -34,7 +35,9 @@ import {
 } from "@/features/ai-chat/queries/ai-chat-query.ts";
 import ConversationList from "@/features/ai-chat/components/conversation-list.tsx";
 import ChatThread from "@/features/ai-chat/components/chat-thread.tsx";
-import { exportChatAsMarkdown } from "@/features/ai-chat/utils/export-chat.ts";
+import { buildChatMarkdown } from "@/features/ai-chat/utils/chat-markdown.ts";
+import { useClipboard } from "@/hooks/use-clipboard";
+import { notifications } from "@mantine/notifications";
 import classes from "@/features/ai-chat/components/ai-chat-window.module.css";
 
 // Default window geometry (from the GitmostAgent.jsx design).
@@ -90,6 +93,7 @@ function clampGeom(g: { left: number; top: number; width: number; height: number
  */
 export default function AiChatWindow() {
   const { t } = useTranslation();
+  const clipboard = useClipboard({ timeout: 500 });
   const queryClient = useQueryClient();
   const [windowOpen, setWindowOpen] = useAtom(aiChatWindowOpenAtom);
   const [activeChatId, setActiveChatId] = useAtom(activeAiChatIdAtom);
@@ -165,16 +169,19 @@ export default function AiChatWindow() {
   const canExport = !!activeChatId && !!messageRows && messageRows.length > 0;
 
   // Build a Markdown export from the already-loaded persisted rows (no network
-  // call) and trigger a browser download. The download dialog is the feedback.
-  const handleExport = useCallback(() => {
+  // call) and copy it to the clipboard. The "Copied" notification is the
+  // feedback.
+  const handleCopy = useCallback(() => {
     if (!activeChatId || !messageRows || messageRows.length === 0) return;
-    exportChatAsMarkdown({
+    const markdown = buildChatMarkdown({
       title: activeChat?.title ?? null,
       chatId: activeChatId,
       rows: messageRows,
       t,
     });
-  }, [activeChatId, messageRows, activeChat, t]);
+    clipboard.copy(markdown);
+    notifications.show({ message: t("Copied") });
+  }, [activeChatId, messageRows, activeChat, clipboard, t]);
 
   // When awaiting a new chat's id, adopt the most-recent chat (the list is
   // ordered newest-first) once it appears.
@@ -334,11 +341,11 @@ export default function AiChatWindow() {
             <button
               type="button"
               className={classes.headerBtn}
-              title={t("Export chat")}
-              aria-label={t("Export chat")}
-              onClick={handleExport}
+              title={t("Copy chat")}
+              aria-label={t("Copy chat")}
+              onClick={handleCopy}
             >
-              <IconFileExport size={14} />
+              {clipboard.copied ? <IconCheck size={14} /> : <IconCopy size={14} />}
             </button>
           )}
           <button

apps/client/src/features/ai-chat/utils/chat-markdown.ts

@@ -1,17 +1,16 @@
 /**
- * Client-only Markdown exporter for an AI agent chat. Serializes the already
+ * Client-only Markdown builder for an AI agent chat. Serializes the already
  * persisted message rows (loaded via `useAiChatMessagesQuery`) into a single
- * Markdown document and triggers a browser download. NO network call is made
- * and NO server/DB code is touched — this reuses the rich "request internals"
- * (tool calls with input/output, per-message token usage, finish/error info)
- * that the chat already holds client-side.
+ * Markdown string suitable for copying to the clipboard. NO network call is
+ * made and NO server/DB code is touched — this reuses the rich "request
+ * internals" (tool calls with input/output, per-message token usage,
+ * finish/error info) that the chat already holds client-side.
  *
  * Only role labels and tool action labels are localized via the passed-in `t`
  * translator; the structural document words (Input/Output/Error/Tokens/...) are
- * plain English constants because the export is a technical artifact.
+ * plain English constants because the output is a technical artifact.
  */
 
-import { saveAs } from "file-saver";
 import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.ts";
 import {
   ToolUiPart,
@@ -23,7 +22,7 @@ import {
 // Minimal translator signature compatible with react-i18next's `t`.
 type Translate = (key: string, values?: Record<string, unknown>) => string;
 
-interface ExportChatArgs {
+interface BuildChatMarkdownArgs {
   title: string | null;
   chatId: string;
   rows: IAiChatMessageRow[];
@@ -62,21 +61,6 @@ function fence(code: string, lang = ""): string {
   return `${delim}${lang}\n${code}\n${delim}`;
 }
 
-/**
- * Build a filesystem-safe slug from a chat title: lowercase, collapse any run
- * of non-alphanumeric characters to a single "-", trim stray dashes, cap the
- * length. Falls back to `chatId` when the title yields an empty slug.
- */
-function slugify(title: string | null, chatId: string): string {
-  const slug = (title ?? "")
-    .toLowerCase()
-    .replace(/[^a-z0-9]+/g, "-")
-    .replace(/^-+|-+$/g, "")
-    .slice(0, 50)
-    .replace(/-+$/g, "");
-  return slug.length > 0 ? slug : chatId;
-}
-
 /** Per-row token count, mirroring the header sum in ai-chat-window.tsx. */
 function rowTokens(usage: {
   inputTokens?: number;
@@ -92,7 +76,7 @@ function rowTokens(usage: {
  * Serialize a chat to a Markdown string. Pure (apart from `new Date()` for the
  * export timestamp), so it is straightforward to unit-test.
  */
-export function buildChatMarkdown(args: ExportChatArgs): string {
+export function buildChatMarkdown(args: BuildChatMarkdownArgs): string {
   const { title, chatId, rows, t } = args;
   const blocks: string[] = [];
 
@@ -179,16 +163,3 @@ export function buildChatMarkdown(args: ExportChatArgs): string {
   // Blank line between blocks so the Markdown renders cleanly.
   return blocks.join("\n\n");
 }
-
-/**
- * Build the Markdown, wrap it in a Blob, and trigger a browser download. The
- * file name is `gitmost-chat-<slug>-<YYYYMMDD>.md`.
- */
-export function exportChatAsMarkdown(args: ExportChatArgs): void {
-  const markdown = buildChatMarkdown(args);
-  const slug = slugify(args.title, args.chatId);
-  const date = new Date().toISOString().slice(0, 10).replace(/-/g, "");
-  const filename = `gitmost-chat-${slug}-${date}.md`;
-  const blob = new Blob([markdown], { type: "text/markdown;charset=utf-8" });
-  saveAs(blob, filename);
-}