refactor(review): address PR #186 re-review (approve-with-comments)

Approve-with-comments re-review; no blockers. All 7 actionable points (8 is a
forward-looking architecture note — recommendation A, keep as-is):

1. chat-markdown.util spec: restore parity coverage of the removed client spec —
   tool error state (+ errorText), unknown-tool fallback (`Ran tool <name>` en /
   `Выполнил инструмент <name>` ru), and the circular-output stringify catch.
2. findAllByChat row cap is now testable (injectable limit) + an int-spec proves
   truncation on a modest volume.
3. Stability: the per-step durability updates are SERIALIZED via a promise chain
   (stepUpdateChain) so they commit in step order — onlyIfStreaming already
   closed the finalize race, this closes inter-step ordering.
4. findAllByChat keeps the NEWEST messages on truncation (order DESC + reverse,
   like findRecent) and logs a warning with chatId, instead of silently dropping
   the newest tail.
5. The LABELS parity comment already references the real path (tool-parts.tsx /
   toolLabelKey) — confirmed accurate.
6. Removed the redundant 'off-by-one boundary' test (strict subset of the two
   adjacent prepareAgentStep cases).
7. Extracted the terminal-finalize dispatch into a shared `applyFinalize`, used
   by BOTH the service's finalizeAssistant and its test — the test now exercises
   the real path, not a copy, so a production drift fails it.

Verified: server build + 325 ai-chat unit + 6 integration; prettier clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.env.example

@@ -149,6 +149,19 @@ MCP_DOCMOST_PASSWORD=
 # your egress drops idle connections faster than ~10s. Default 10000 (10 s).
 # AI_STREAM_KEEPALIVE_MS=10000
 
+# Silence timeout (ms) for EXTERNAL-MCP transport ONLY (not the chat provider).
+# Tighter than AI_STREAM_TIMEOUT_MS so a byte-silent/hung MCP server is broken in
+# ~5 min instead of 15. Note it also cuts a legitimately long but byte-silent
+# single tool call (a slow crawl that emits nothing until done) and an SSE
+# transport idling >5 min BETWEEN tool calls. Default 300000 (5 min).
+# AI_MCP_STREAM_TIMEOUT_MS=300000
+
+# Total wall-clock cap (ms) for ONE external MCP tool call (app-level, not
+# transport). Aborts a tool that keeps the socket warm (SSE heartbeats / trickle)
+# but never returns a result — which the silence timeout above never breaks.
+# Default 900000 (15 min).
+# AI_MCP_CALL_TIMEOUT_MS=900000
+
 # --- Anonymous public-share AI assistant ---
 # Opt-in per workspace (AI settings -> "public share assistant"; off by default).
 # When enabled, anonymous visitors of a published share can ask an AI about that

CHANGELOG.md

@@ -12,10 +12,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- **Persistent AI-chat history as the source of truth + server-side export.**
+  An assistant turn is now persisted to the database step by step: the row is
+  inserted upfront as `streaming` and updated as each agent step finishes, then
+  finalized once to `completed`/`error`/`aborted`. A process that dies mid-turn
+  keeps every finished step, and a startup sweep flips any dangling `streaming`
+  row (untouched for 10 minutes) to `aborted`. Chat "Copy" now exports
+  server-side from these rows (`POST /ai-chat/export`) rather than from live
+  client state, so the export is identical whether a chat is freshly streaming,
+  just switched to, or reloaded — and is available from the first turn of a new
+  chat. (#183, #174)
+
 - **AI-agent attribution for MCP writes.** Comments (and pages) created through
   the MCP endpoint by a dedicated agent account are now badged as "AI", with
   unspoofable provenance derived from a per-user `is_agent` flag (not from the
-  request body). **Operator setup:** use a *dedicated* service account for the
+  request body). **Operator setup:** use a _dedicated_ service account for the
   MCP fallback and set the flag with SQL —
   `UPDATE users SET is_agent = true WHERE email = '<mcp-account>'`. Never flag a
   human or shared account, or its normal edits get mis-attributed as AI. See the
@@ -150,8 +161,7 @@ embeds — plus a large batch of security hardening and test coverage.
 - Page templates: import `ThrottleModule` so collab boots, never strand an
   in-flight page-embed id, and add defense-in-depth workspace checks.
 - Pages: `movePage` cycle guard with no phantom `PAGE_MOVED` event.
-- Import: surface the real error cause from `/pages/import` instead of a generic
-  400.
+- Import: surface the real error cause from `/pages/import` instead of a generic 400.
 
 ### Security
 

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

@@ -258,6 +258,7 @@
   "Copy to space": "Copy to space",
   "Copy chat": "Copy chat",
   "Copied": "Copied",
+  "Failed to export chat": "Failed to export chat",
   "Duplicate": "Duplicate",
   "Select a user": "Select a user",
   "Select a group": "Select a group",

apps/client/public/locales/ru-RU/translation.json

@@ -257,6 +257,7 @@
   "Copy": "Копировать",
   "Copy to space": "Копировать в пространство",
   "Copied": "Скопировано",
+  "Failed to export chat": "Не удалось экспортировать чат",
   "Duplicate": "Дублировать",
   "Select a user": "Выберите пользователя",
   "Select a group": "Выберите группу",

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

@@ -6,7 +6,6 @@ import {
   useRef,
   useState,
 } from "react";
-import { type UIMessage } from "@ai-sdk/react";
 import { Group, Loader, Tooltip } from "@mantine/core";
 import {
   IconArrowsDiagonal,
@@ -40,7 +39,7 @@ 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 { buildChatMarkdown } from "@/features/ai-chat/utils/chat-markdown.ts";
+import { exportAiChat } from "@/features/ai-chat/services/ai-chat-service.ts";
 import { useChatSession } from "@/features/ai-chat/hooks/use-chat-session.ts";
 import {
   shouldCollapseOnOutsidePointer,
@@ -121,7 +120,7 @@ function clampGeom(g: {
  * ported from the GitmostAgent.jsx design.
  */
 export default function AiChatWindow() {
-  const { t } = useTranslation();
+  const { t, i18n } = useTranslation();
   const clipboard = useClipboard({ timeout: 500 });
   const queryClient = useQueryClient();
   const [windowOpen, setWindowOpen] = useAtom(aiChatWindowOpenAtom);
@@ -162,30 +161,11 @@ export default function AiChatWindow() {
   const { data: messageRows, isLoading: messagesLoading } =
     useAiChatMessagesQuery(activeChatId ?? undefined);
 
-  // Live snapshot of the active thread's useChat state, kept up to date by
-  // ChatThread. Lets the export include the in-progress (not-yet-persisted)
-  // streaming turn. A ref avoids re-rendering this window on every token.
-  const liveThreadRef = useRef<{
-    messages: UIMessage[];
-    isStreaming: boolean;
-    banner: string | null;
-  }>({
-    messages: [],
-    isStreaming: false,
-    banner: null,
-  });
-
   // Live turn-token total (reasoning + output) for the in-flight turn, pushed up
   // (THROTTLED to ~8 Hz inside ChatThread) so the header badge ticks mid-stream.
   // `null` means no turn is in flight -> the badge falls back to the persisted
   // context size below.
   const [liveTurnTokens, setLiveTurnTokens] = useState<number | null>(null);
-  // Whether the on-screen thread currently holds at least one message. Reported
-  // reactively by ChatThread (the live snapshot lives in a non-reactive ref). This
-  // lets the "Copy chat" button stay available for a brand-new, not-yet-persisted
-  // chat whose first turn is in flight or was interrupted — that case has no
-  // persisted rows yet, so a persisted-rows-only gate would hide the button (#174).
-  const [hasLiveContent, setHasLiveContent] = useState(false);
 
   // The page the user is currently viewing. AiChatWindow lives in a pathless
   // parent layout route, so useParams() can't see :pageSlug. Match the full
@@ -214,6 +194,7 @@ export default function AiChatWindow() {
     threadKey,
     waitingForHistory,
     onTurnFinished,
+    onServerChatId,
     cancelPendingAdoption,
   } = useChatSession({
     activeChatId,
@@ -254,20 +235,19 @@ export default function AiChatWindow() {
     [cancelPendingAdoption, setActiveChatId, setDraft, setSelectedRoleId],
   );
 
-  // The active chat object (for its title) and an export gate: only enable the
-  // export button when an existing chat with loaded persisted rows is active.
+  // The active chat object (for its title) and an export gate. The export is now
+  // SERVER-sourced (the DB is the single source of truth — #183): the assistant
+  // row is persisted upfront + per step, so even a brand-new chat whose first
+  // turn is streaming/interrupted has a server row to render. Enable the button
+  // whenever a persisted chat is active (`activeChatId` is set). For a BRAND-NEW
+  // chat that id is adopted EARLY — at the stream's `start` chunk via
+  // onServerChatId (#174) — so the Copy button is available during the first
+  // turn's stream, not only after it terminates.
   const activeChat = useMemo(
     () => chats?.items?.find((c) => c.id === activeChatId) ?? null,
     [chats, activeChatId],
   );
-  // Export is available when there is anything to export: either persisted rows
-  // for the active chat, OR a live on-screen thread with at least one message.
-  // The live arm covers a brand-new chat whose first turn is streaming or was
-  // interrupted before the server persisted any row (#174); the persisted arm is
-  // the steady-state path for an already-saved chat (#160).
-  const canExport =
-    hasLiveContent ||
-    (!!activeChatId && !!messageRows && messageRows.length > 0);
+  const canExport = !!activeChatId;
 
   // The role to display in the header and as the assistant's name. Prefer the
   // persisted role of an existing chat (chat-list JOIN); fall back to the role
@@ -284,53 +264,21 @@ export default function AiChatWindow() {
     return picked ? { name: picked.name, emoji: picked.emoji } : null;
   }, [activeChat, enabledRoles, selectedRoleId]);
 
-  // Build a Markdown export from the already-loaded persisted rows (no network
-  // call) and copy it to the clipboard. The "Copied" notification is the
-  // feedback.
-  const handleCopy = useCallback(() => {
-    // Export gate. There must be SOMETHING to export — either a live on-screen
-    // message or a persisted row. A brand-new chat whose first turn is streaming
-    // or was interrupted has live messages but no persisted rows yet; it still
-    // exports the on-screen thread WYSIWYG (#174). Only a truly empty chat (no
-    // live messages and no rows) is non-exportable (the button is hidden too —
-    // see `canExport`).
-    const live = liveThreadRef.current;
-    const hasRows = !!messageRows && messageRows.length > 0;
-    if (live.messages.length === 0 && !hasRows) return;
-    // WYSIWYG export: the live on-screen messages ARE the document (so a partial
-    // reply from an interrupted turn — which never reached the persisted rows —
-    // is exported just as it appears). The persisted rows enrich each live
-    // message (token usage / error / timestamp) by id and serve as the fallback
-    // when the live mirror is empty. The on-screen banner is appended too. See
-    // issues #160 and #174. `chatId` may be null for a not-yet-saved chat — use a
-    // placeholder so the header line still renders.
-    const markdown = buildChatMarkdown({
-      title: activeChat?.title ?? null,
-      chatId: activeChatId ?? "unsaved",
-      live: live.messages.map((m) => ({
-        id: m.id,
-        role: m.role,
-        parts: (m.parts ?? []) as { type: string; text?: string }[],
-        metadata: m.metadata as
-          | {
-              usage?: {
-                inputTokens?: number;
-                outputTokens?: number;
-                totalTokens?: number;
-                reasoningTokens?: number;
-              };
-              error?: string;
-            }
-          | undefined,
-      })),
-      rows: messageRows,
-      isStreaming: live.isStreaming,
-      banner: live.banner,
-      t,
-    });
+  // Fetch the server-rendered Markdown export and copy it to the clipboard. The
+  // server is the single source of truth (#183): it renders the transcript from
+  // the persisted rows — including an interrupted turn's in-progress row — so the
+  // export is identical whether the chat is freshly streaming, just switched to,
+  // or reloaded. The `lang` of the active i18n drives the few localized labels.
+  const handleCopy = useCallback(async () => {
+    if (!activeChatId) return;
+    try {
+      const markdown = await exportAiChat(activeChatId, i18n.language);
       clipboard.copy(markdown);
       notifications.show({ message: t("Copied") });
-  }, [activeChatId, messageRows, activeChat, clipboard, t]);
+    } catch {
+      notifications.show({ message: t("Failed to export chat"), color: "red" });
+    }
+  }, [activeChatId, clipboard, t, i18n.language]);
 
   // Current context size for the active chat: how much the conversation now
   // occupies in the model's context window — NOT the cumulative tokens spent.
@@ -685,9 +633,8 @@ export default function AiChatWindow() {
               onRolePicked={(role) => setSelectedRoleId(role.id)}
               assistantName={currentRole?.name}
               onTurnFinished={onTurnFinished}
-              liveStateRef={liveThreadRef}
+              onServerChatId={onServerChatId}
               onLiveTurnTokens={setLiveTurnTokens}
-              onLiveContentChange={setHasLiveContent}
             />
           )}
         </div>

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

@@ -1,11 +1,4 @@
-import {
-  useCallback,
-  useEffect,
-  useMemo,
-  useRef,
-  useState,
-  type MutableRefObject,
-} from "react";
+import { useCallback, useEffect, useMemo, useRef, useState } from "react";
 import { generateId } from "ai";
 import { ActionIcon, Box, Group, Stack, Text } from "@mantine/core";
 import { IconClockHour4, IconX } from "@tabler/icons-react";
@@ -68,30 +61,18 @@ interface ChatThreadProps {
    *  authoritative id the server streamed on the assistant message metadata, or
    *  undefined on a failed turn — see adopt-chat-id.ts for the full #137 design. */
   onTurnFinished: (serverChatId?: string) => void;
-  /** Parent-owned ref that this thread keeps updated with its live useChat
-   *  snapshot (full message list + streaming flag), so the header's
-   *  "Copy chat" export can include the in-progress, not-yet-persisted
-   *  assistant message. A ref (not state) avoids re-rendering the parent on
-   *  every streamed delta. */
-  liveStateRef?: MutableRefObject<{
-    messages: UIMessage[];
-    isStreaming: boolean;
-    banner: string | null;
-  }>;
+  /** Called EARLY (at the stream's `start` chunk) with the authoritative server
+   *  chat id streamed on the assistant message metadata, so a brand-new chat
+   *  adopts its real id WHILE the first turn is still streaming (#174 — makes the
+   *  Copy/export button available mid-stream). Distinct from onTurnFinished,
+   *  which fires only at the terminal outcome. */
+  onServerChatId?: (serverChatId?: string) => void;
   /** Reports the live turn-token total (reasoning + output) for the in-flight
    *  turn so the parent can show a header badge that ticks mid-stream. THROTTLED
    *  here (~8 Hz) so the parent re-renders a handful of times a second, not on
    *  every streamed delta. Called with `null` when no turn is in flight (the
    *  parent then reverts the badge to the persisted context size). */
   onLiveTurnTokens?: (tokens: number | null) => void;
-  /** Reports whether the live thread currently holds at least one message, so the
-   *  parent can gate the "Copy chat" button on the on-screen thread rather than on
-   *  the persisted rows alone. This stays truthy for a brand-new, not-yet-saved
-   *  chat the moment its first user message appears — so an interrupted very first
-   *  turn (no persisted rows yet) is still exportable (#174). Called with `false`
-   *  on unmount so a thread torn down by `key` on chat switch can't leave the
-   *  button enabled for the next, possibly empty, chat. */
-  onLiveContentChange?: (hasContent: boolean) => void;
 }
 
 /**
@@ -135,9 +116,8 @@ export default function ChatThread({
   onRolePicked,
   assistantName,
   onTurnFinished,
-  liveStateRef,
+  onServerChatId,
   onLiveTurnTokens,
-  onLiveContentChange,
 }: ChatThreadProps) {
   const { t } = useTranslation();
 
@@ -306,6 +286,26 @@ export default function ChatThread({
   // Keep the flush helper pointed at the latest sendMessage instance.
   sendMessageRef.current = sendMessage;
 
+  // EARLY chat-id adoption (#174): the server streams the authoritative chat id
+  // on the assistant message metadata at the `start` chunk (message.metadata.
+  // chatId — see adopt-chat-id.ts / chatStreamMetadata). Forward it to the parent
+  // AS SOON AS it appears (mid-stream), so a brand-new chat adopts its real id
+  // WHILE the first turn is still streaming and activeChatId-gated affordances
+  // (the Copy/export button) light up immediately, instead of only at onFinish.
+  // Keyed by the last-seen id so we forward each distinct id exactly once. The
+  // parent's onServerChatId is idempotent and a no-op once the chat has an id.
+  const lastForwardedChatIdRef = useRef<string | undefined>(undefined);
+  useEffect(() => {
+    if (!onServerChatId) return;
+    const tail = messages[messages.length - 1];
+    if (tail?.role !== "assistant") return;
+    const serverChatId = extractServerChatId(tail);
+    if (!serverChatId || serverChatId === lastForwardedChatIdRef.current)
+      return;
+    lastForwardedChatIdRef.current = serverChatId;
+    onServerChatId(serverChatId);
+  }, [messages, onServerChatId]);
+
   // Live "turn was interrupted" marker for the CURRENT session. The red error
   // banner (driven by `error`) covers the error case; this covers an aborted
   // turn, distinguishing a manual Stop (`isAbort`) from a dropped connection
@@ -328,44 +328,6 @@ export default function ChatThread({
   // the SAME on-screen banner text can be mirrored into the export (issue #160).
   const errorView = error ? describeChatError(error.message ?? "", t) : null;
 
-  // The exact banner the user sees under the message list, flattened to a single
-  // string for the "Copy chat" export so the artifact records the interruption
-  // WYSIWYG. Mirrors the JSX precedence below: error first, else the stop notice.
-  const banner = errorView
-    ? errorView.detail
-      ? `${errorView.title} — ${errorView.detail}`
-      : errorView.title
-    : stopNotice === "manual"
-      ? t("Response stopped.")
-      : stopNotice === "disconnect"
-        ? t("Connection lost — the answer was interrupted.")
-        : null;
-
-  // Mirror the live useChat snapshot into the parent-owned ref so the export
-  // (handled in AiChatWindow) can include the in-progress streaming turn AND the
-  // on-screen banner. The cleanup clears the ref on unmount so a thread torn down
-  // by `key` on chat switch can't leak its (possibly still-streaming) tail into
-  // the next chat's export before the new thread's effect repopulates the ref.
-  useEffect(() => {
-    if (!liveStateRef) return;
-    liveStateRef.current = { messages, isStreaming, banner };
-    return () => {
-      liveStateRef.current = { messages: [], isStreaming: false, banner: null };
-    };
-  }, [liveStateRef, messages, isStreaming, banner]);
-
-  // Reactively report "the live thread has content" to the parent. `liveStateRef`
-  // above is a ref (deliberately non-reactive so streaming deltas don't re-render
-  // the parent), so the export button needs a SEPARATE reactive signal to flip on
-  // for a not-yet-persisted chat. Keyed on the boolean only — identical values are
-  // a no-op setState in the parent, so this does not add per-delta re-renders.
-  const hasLiveContent = messages.length > 0;
-  useEffect(() => {
-    if (!onLiveContentChange) return;
-    onLiveContentChange(hasLiveContent);
-    return () => onLiveContentChange(false);
-  }, [onLiveContentChange, hasLiveContent]);
-
   // Report the live turn-token total to the parent header badge, THROTTLED to
   // ~8 Hz so the parent re-renders a few times a second instead of on every
   // streamed delta. The tail assistant message's reasoning+output (estimate while

apps/client/src/features/ai-chat/hooks/use-chat-session.test.tsx

@@ -64,7 +64,10 @@ describe("useChatSession", () => {
     result.current.onTurnFinished(undefined);
     expect(setActiveChatId).not.toHaveBeenCalled();
     // The refetch lands with the new row => adopt it.
-    rerender({ activeChatId: null, chats: { items: [{ id: "x" }, { id: "new" }] } });
+    rerender({
+      activeChatId: null,
+      chats: { items: [{ id: "x" }, { id: "new" }] },
+    });
     expect(setActiveChatId).toHaveBeenCalledWith("new");
   });
 
@@ -88,7 +91,10 @@ describe("useChatSession", () => {
     });
     result.current.onTurnFinished(undefined);
     // a was deleted, new was added — same length, but membership changed.
-    rerender({ activeChatId: null, chats: { items: [{ id: "b" }, { id: "new" }] } });
+    rerender({
+      activeChatId: null,
+      chats: { items: [{ id: "b" }, { id: "new" }] },
+    });
     expect(setActiveChatId).toHaveBeenCalledWith("new");
   });
 
@@ -171,6 +177,40 @@ describe("useChatSession", () => {
     expect(setActiveChatId).not.toHaveBeenCalledWith("late");
   });
 
+  it("#174 early adopt: onServerChatId adopts the streamed id mid-stream (Copy button available during the first turn)", () => {
+    // Brand-new chat: no id yet. The server streams the real chat id "A" on the
+    // `start` chunk WHILE the first turn is still streaming (before onTurnFinished
+    // fires at the terminal outcome). The hook must adopt it immediately so the
+    // window's activeChatId-gated Copy/export button lights up during the stream.
+    const { result, setActiveChatId } = setup({
+      activeChatId: null,
+      chats: { items: [] },
+    });
+    result.current.onServerChatId("A");
+    expect(setActiveChatId).toHaveBeenCalledWith("A");
+  });
+
+  it("#174 early adopt is in-place: threadKey stays stable (live stream not torn down)", () => {
+    const chats = { items: [] };
+    const { result, rerender } = setup({ activeChatId: null, chats });
+    const keyBefore = result.current.threadKey;
+    result.current.onServerChatId("A");
+    // Parent reflects the adopted id back in; the SAME mount key is kept so the
+    // in-flight useChat store (the streaming turn) is preserved.
+    rerender({ activeChatId: "A", chats });
+    expect(result.current.threadKey).toBe(keyBefore);
+  });
+
+  it("#174 early adopt: no-op for an existing chat and for a missing id", () => {
+    const { result, setActiveChatId } = setup({
+      activeChatId: "chat-1",
+      chats: { items: [{ id: "chat-1" }] },
+    });
+    result.current.onServerChatId("chat-1"); // already has an id
+    result.current.onServerChatId(undefined); // no streamed id
+    expect(setActiveChatId).not.toHaveBeenCalled();
+  });
+
   it("in-place adopt keeps threadKey stable; an external switch remounts", () => {
     const chats = { items: [{ id: "B" }] };
     const { result, rerender } = setup({ activeChatId: null, chats });

apps/client/src/features/ai-chat/hooks/use-chat-session.ts

@@ -34,6 +34,13 @@ export interface UseChatSessionResult {
   /** Call when a turn finishes; `serverChatId` is the authoritative streamed id
    *  (undefined on a failed turn). Handles new-chat id adoption + invalidations. */
   onTurnFinished: (serverChatId?: string) => void;
+  /** Call EARLY (at the stream's `start` chunk) with the authoritative streamed
+   *  chat id so a brand-new chat adopts its real id WHILE its first turn is still
+   *  streaming — making `activeChatId`-gated affordances (e.g. the Copy/export
+   *  button, #174) available immediately. In-place adoption only (same mount key,
+   *  no list/messages invalidation — that is left to onTurnFinished at the end).
+   *  Idempotent and a no-op once the chat already has an id. */
+  onServerChatId: (serverChatId?: string) => void;
   /** Disarm any pending error-path new-chat fallback. The window calls this from
    *  startNewChat/selectChat so a late refetch can't yank the user back into a
    *  just-failed chat after they explicitly moved on. */
@@ -85,10 +92,7 @@ export function useChatSession(
   // `newThread`/`switchThread` to (re)mount, `adoptThread` for in-place adoption.
   // Initial: a non-null activeChatId switches to it; a null one gets a fresh
   // session key with no chat id yet.
-  const [thread, dispatch] = useReducer(
-    threadSessionReducer,
-    undefined,
-    () =>
+  const [thread, dispatch] = useReducer(threadSessionReducer, undefined, () =>
     activeChatId === null
       ? newThread(`new-${generateId()}`)
       : switchThread(activeChatId),
@@ -150,6 +154,31 @@ export function useChatSession(
     [chats, setActiveChatId, onInvalidateChatList, onInvalidateChatMessages],
   );
 
+  // EARLY adoption (#174): adopt the authoritative streamed chat id the moment
+  // the server emits it on the `start` chunk, so a brand-new chat gets its real
+  // `activeChatId` WHILE its first turn streams — not only at terminal
+  // onTurnFinished. This makes the activeChatId-gated Copy/export button
+  // available during the first turn. Pure in-place adoption (same mount key, like
+  // the primary path) with NO invalidation: the list/messages refresh stays on
+  // onTurnFinished at the end of the turn. Reads the live id from the ref so a
+  // repeat call after adoption is a no-op (resolveAdoptedChatId only fires for a
+  // still-new chat).
+  const onServerChatId = useCallback(
+    (serverChatId?: string) => {
+      const adopted = resolveAdoptedChatId(
+        activeChatIdRef.current,
+        serverChatId,
+      );
+      if (!adopted) return;
+      activeChatIdRef.current = adopted;
+      setActiveChatId(adopted);
+      dispatch({ type: "adopt", chatId: adopted });
+      // Early adoption beat the error-path fallback to it — disarm.
+      pendingNewChatRef.current = null;
+    },
+    [setActiveChatId],
+  );
+
   // FALLBACK resolver. Armed only by onTurnFinished when a brand-new chat's first
   // turn errored before the `start` chunk (no authoritative id streamed). Once
   // the per-user list refetch lands with the just-created row, adopt the SINGLE
@@ -233,6 +262,7 @@ export function useChatSession(
     threadKey: thread.key,
     waitingForHistory,
     onTurnFinished,
+    onServerChatId,
     cancelPendingAdoption,
   };
 }

apps/client/src/features/ai-chat/services/ai-chat-service.ts

@@ -50,6 +50,24 @@ export async function deleteAiChat(chatId: string): Promise<void> {
   await api.post("/ai-chat/delete", { chatId });
 }
 
+/**
+ * Export a chat to Markdown (#183). The server renders the transcript from the
+ * persisted rows (the DB is the single source of truth — including an
+ * interrupted turn's in-progress row, persisted upfront + per step), so the
+ * client just copies the returned string. `lang` localizes the few fixed
+ * role/tool labels; defaults to English server-side when omitted.
+ */
+export async function exportAiChat(
+  chatId: string,
+  lang?: string,
+): Promise<string> {
+  const req = await api.post<{ markdown: string }>("/ai-chat/export", {
+    chatId,
+    lang,
+  });
+  return req.data.markdown;
+}
+
 /**
  * Agent roles API (`/ai-chat/roles`). `list` is available to any workspace
  * member (for the chat-creation picker); create/update/delete are admin-only
@@ -76,6 +94,8 @@ export async function updateAiRole(data: IAiRoleUpdate): Promise<IAiRole> {
 
 /** Soft-delete a role (admin). */
 export async function deleteAiRole(id: string): Promise<{ success: true }> {
-  const req = await api.post<{ success: true }>("/ai-chat/roles/delete", { id });
+  const req = await api.post<{ success: true }>("/ai-chat/roles/delete", {
+    id,
+  });
   return req.data;
 }

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

@@ -1,747 +0,0 @@
-import { describe, it, expect } from "vitest";
-import { buildChatMarkdown } from "@/features/ai-chat/utils/chat-markdown.ts";
-import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.ts";
-
-/**
- * Tests for the client-only Markdown export builder. The output embeds a live
- * `new Date().toISOString()` export timestamp; we never assert that value, only
- * the deterministic structure (headings, numbering, fenced blocks, totals).
- *
- * A pass-through translator keeps role/tool labels predictable so the
- * structural assertions are stable without an i18n runtime.
- */
-const t = (key: string, values?: Record<string, unknown>): string => {
-  if (values && typeof values.name === "string") {
-    return key.replace("{{name}}", values.name);
-  }
-  return key;
-};
-
-function row(partial: Partial<IAiChatMessageRow>): IAiChatMessageRow {
-  return {
-    id: partial.id ?? "id",
-    role: partial.role ?? "user",
-    content: partial.content ?? null,
-    metadata: partial.metadata ?? null,
-    createdAt: partial.createdAt ?? "2026-06-21T00:00:00.000Z",
-  };
-}
-
-describe("buildChatMarkdown — structure", () => {
-  it("emits the title heading, chat id and message count", () => {
-    const md = buildChatMarkdown({
-      title: "My chat",
-      chatId: "chat-123",
-      rows: [],
-      t,
-    });
-    expect(md).toContain("# My chat");
-    expect(md).toContain("- Chat ID: `chat-123`");
-    expect(md).toContain("- Messages: 0");
-    expect(md).toContain("- Exported:"); // timestamp present, value not asserted
-  });
-
-  it("falls back to the translated 'Untitled chat' for empty/blank titles", () => {
-    expect(
-      buildChatMarkdown({ title: null, chatId: "c", rows: [], t }),
-    ).toContain("# Untitled chat");
-    expect(
-      buildChatMarkdown({ title: "   ", chatId: "c", rows: [], t }),
-    ).toContain("# Untitled chat");
-  });
-
-  it("numbers rows sequentially with role headings", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({ role: "user", content: "hi" }),
-        row({ role: "assistant", content: "hello" }),
-        row({ role: "user", content: "again" }),
-      ],
-      t,
-    });
-    expect(md).toContain("## 1. You");
-    expect(md).toContain("## 2. AI agent");
-    expect(md).toContain("## 3. You");
-    // Heading numbering is strictly index+1, not e.g. role-relative.
-    expect(md).not.toContain("## 0.");
-  });
-
-  it("renders the per-row text content from `content` when no metadata.parts", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ role: "user", content: "plain body" })],
-      t,
-    });
-    expect(md).toContain("plain body");
-  });
-});
-
-describe("buildChatMarkdown — text parts", () => {
-  it("skips empty / whitespace-only text parts", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "ignored-content",
-          metadata: {
-            parts: [
-              { type: "text", text: "   " },
-              { type: "text", text: "" },
-              { type: "text", text: "kept line" },
-              // eslint-disable-next-line @typescript-eslint/no-explicit-any
-            ] as any,
-          },
-        }),
-      ],
-      t,
-    });
-    expect(md).toContain("kept line");
-    // Whitespace-only part contributed no block of its own.
-    expect(md).not.toContain("   \n\n");
-    // When metadata.parts exists, the plain `content` fallback is NOT used.
-    expect(md).not.toContain("ignored-content");
-  });
-});
-
-describe("buildChatMarkdown — tool parts", () => {
-  it("renders a tool label, name, state and fenced Input/Output blocks", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "",
-          metadata: {
-            parts: [
-              {
-                type: "tool-getPage",
-                state: "output-available",
-                input: { pageId: "p1" },
-                output: { id: "p1", title: "Home" },
-                // eslint-disable-next-line @typescript-eslint/no-explicit-any
-              } as any,
-            ],
-          },
-        }),
-      ],
-      t,
-    });
-    // Known tool name maps to its label key; raw name in backticks; done state.
-    expect(md).toContain("**Tool: Read page** (`getPage`) — done");
-    expect(md).toContain("Input:");
-    expect(md).toContain("Output:");
-    // Fenced JSON blocks contain the stringified payloads.
-    expect(md).toContain('"pageId": "p1"');
-    expect(md).toContain('"title": "Home"');
-    expect(md).toContain("```json");
-  });
-
-  it("renders the generic label for an unknown tool and surfaces errorText", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "",
-          metadata: {
-            parts: [
-              {
-                type: "tool-mysteryTool",
-                state: "output-error",
-                input: { a: 1 },
-                errorText: "boom",
-                // eslint-disable-next-line @typescript-eslint/no-explicit-any
-              } as any,
-            ],
-          },
-        }),
-      ],
-      t,
-    });
-    expect(md).toContain(
-      "**Tool: Ran tool mysteryTool** (`mysteryTool`) — error",
-    );
-    expect(md).toContain("**Error:** boom");
-  });
-
-  it("does not throw on a circular tool input (falls back to String)", () => {
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    const circular: any = {};
-    circular.self = circular;
-    expect(() =>
-      buildChatMarkdown({
-        title: "t",
-        chatId: "c",
-        rows: [
-          row({
-            role: "assistant",
-            content: "",
-            metadata: {
-              parts: [
-                {
-                  type: "tool-getPage",
-                  state: "input-available",
-                  input: circular,
-                  // eslint-disable-next-line @typescript-eslint/no-explicit-any
-                } as any,
-              ],
-            },
-          }),
-        ],
-        t,
-      }),
-    ).not.toThrow();
-  });
-});
-
-describe("buildChatMarkdown — fence anti-breakout", () => {
-  it("lengthens the delimiter so embedded ``` cannot break out of the block", () => {
-    // Tool input whose stringified string form contains a literal ``` run.
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "",
-          metadata: {
-            parts: [
-              {
-                type: "tool-getPage",
-                state: "output-available",
-                // A bare string passes through stringify() verbatim.
-                input: "before ``` after",
-                output: "x",
-                // eslint-disable-next-line @typescript-eslint/no-explicit-any
-              } as any,
-            ],
-          },
-        }),
-      ],
-      t,
-    });
-    // The fence around the 3-backtick content must use at least 4 backticks so
-    // the embedded ``` run cannot terminate the block.
-    expect(md).toContain("````json\nbefore ``` after\n````");
-    // Robust anti-breakout check: the opening fence delimiter is strictly
-    // longer than the longest backtick run inside the wrapped content. (A naive
-    // `not.toContain("```json...")` is a false negative — a 4-backtick fence
-    // textually contains the 3-backtick substring.)
-    const open = md.match(/(`{3,})json\nbefore/);
-    expect(open).not.toBeNull();
-    expect(open![1].length).toBeGreaterThan(3); // > the 3-backtick run in content
-  });
-
-  it("uses a 5-backtick fence when the content has a 4-backtick run", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "",
-          metadata: {
-            parts: [
-              {
-                type: "tool-getPage",
-                state: "output-available",
-                input: "a ```` b",
-                // eslint-disable-next-line @typescript-eslint/no-explicit-any
-              } as any,
-            ],
-          },
-        }),
-      ],
-      t,
-    });
-    expect(md).toContain("`````json\na ```` b\n`````");
-  });
-});
-
-describe("buildChatMarkdown — token totals", () => {
-  it("prints the total-tokens line only when the summed usage is > 0", () => {
-    const withTokens = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: { usage: { inputTokens: 10, outputTokens: 5 } },
-        }),
-      ],
-      t,
-    });
-    expect(withTokens).toContain("- Total tokens: 15");
-    // Per-row usage footer too.
-    expect(withTokens).toContain("_Tokens — in: 10, out: 5, total: 15_");
-  });
-
-  it("omits the total-tokens line when the sum is 0 / usage absent", () => {
-    const noTokens = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({ role: "user", content: "hi" }),
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: { usage: { inputTokens: 0, outputTokens: 0 } },
-        }),
-      ],
-      t,
-    });
-    expect(noTokens).not.toContain("- Total tokens:");
-  });
-
-  it("uses totalTokens when present rather than summing in/out", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: {
-            usage: { inputTokens: 3, outputTokens: 4, totalTokens: 99 },
-          },
-        }),
-      ],
-      t,
-    });
-    expect(md).toContain("- Total tokens: 99");
-  });
-
-  it("appends the reasoning figure to the row footer when reasoningTokens > 0", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: {
-            usage: { inputTokens: 10, outputTokens: 8, reasoningTokens: 3 },
-          },
-        }),
-      ],
-      t,
-    });
-    expect(md).toContain("_Tokens — in: 10, out: 8, reasoning: 3, total: 18_");
-  });
-
-  it("omits the reasoning figure when reasoningTokens is 0 / absent", () => {
-    const zero = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: {
-            usage: { inputTokens: 10, outputTokens: 5, reasoningTokens: 0 },
-          },
-        }),
-      ],
-      t,
-    });
-    expect(zero).toContain("_Tokens — in: 10, out: 5, total: 15_");
-    expect(zero).not.toContain("reasoning:");
-
-    const absent = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          role: "assistant",
-          content: "x",
-          metadata: { usage: { inputTokens: 10, outputTokens: 5 } },
-        }),
-      ],
-      t,
-    });
-    expect(absent).not.toContain("reasoning:");
-  });
-});
-
-// A minimal on-screen (live) message, matching the subset buildChatMarkdown reads.
-function live(partial: {
-  id?: string;
-  role?: string;
-  parts?: { type: string; text?: string }[];
-  metadata?: { usage?: Record<string, number>; error?: string };
-}) {
-  return {
-    id: partial.id ?? "live-id",
-    role: partial.role ?? "assistant",
-    parts: partial.parts ?? [],
-    metadata: partial.metadata,
-  };
-}
-
-describe("buildChatMarkdown — live (WYSIWYG) source", () => {
-  it("uses the live messages as the document (what's on screen), numbered from 1", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      // Persisted rows hold only the user turn; the assistant reply is live-only.
-      rows: [row({ id: "u1", role: "user", content: "persisted user" })],
-      live: [
-        live({
-          id: "u1",
-          role: "user",
-          parts: [{ type: "text", text: "on-screen user" }],
-        }),
-        live({
-          id: "a1",
-          role: "assistant",
-          parts: [{ type: "text", text: "on-screen reply" }],
-        }),
-      ],
-      isStreaming: false,
-      t,
-    });
-    expect(md).toContain("## 1. You");
-    expect(md).toContain("## 2. AI agent");
-    expect(md).toContain("on-screen user");
-    expect(md).toContain("on-screen reply");
-    // Message count reflects the LIVE document, not rows + live.
-    expect(md).toContain("- Messages: 2");
-  });
-
-  it("captures a partial reply from an interrupted (non-streaming) turn — no 'generating' note", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ id: "u1", role: "user", content: "q" })],
-      live: [
-        live({ id: "u1", role: "user", parts: [{ type: "text", text: "q" }] }),
-        live({
-          id: "a-live",
-          role: "assistant",
-          parts: [{ type: "text", text: "partial plan before the drop" }],
-        }),
-      ],
-      isStreaming: false, // the stream dropped — not streaming anymore
-      banner: "Connection lost — the answer was interrupted.",
-      t,
-    });
-    // The partial assistant answer that was on screen IS in the export.
-    expect(md).toContain("partial plan before the drop");
-    // It is NOT flagged still-generating (the turn is over, just interrupted).
-    expect(md).not.toContain("still being generated");
-    // The on-screen banner is recorded at the end.
-    expect(md).toContain("Connection lost — the answer was interrupted.");
-  });
-
-  it("flags ONLY the tail assistant as still generating, and only while streaming", () => {
-    const streaming = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [],
-      live: [
-        live({
-          id: "a",
-          role: "assistant",
-          parts: [{ type: "text", text: "done earlier" }],
-        }),
-        live({
-          id: "u",
-          role: "user",
-          parts: [{ type: "text", text: "next q" }],
-        }),
-        live({
-          id: "b",
-          role: "assistant",
-          parts: [{ type: "text", text: "streaming now" }],
-        }),
-      ],
-      isStreaming: true,
-      t,
-    });
-    // Exactly one "still being generated" note (the tail assistant).
-    expect(streaming.match(/still being generated/g)?.length).toBe(1);
-
-    const idle = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [],
-      live: [
-        live({
-          id: "b",
-          role: "assistant",
-          parts: [{ type: "text", text: "final" }],
-        }),
-      ],
-      isStreaming: false,
-      t,
-    });
-    expect(idle).not.toContain("still being generated");
-  });
-
-  it("does NOT flag a completed assistant as generating when the streaming tail is a user message", () => {
-    // The `status === "submitted"` window: the user just sent, isStreaming is
-    // already true, but the new assistant turn has no message yet so the tail is
-    // the USER message. The previous assistant answer is complete on screen and
-    // must not be marked still-generating (WYSIWYG; regression for #160 review).
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [],
-      live: [
-        live({
-          id: "a",
-          role: "assistant",
-          parts: [{ type: "text", text: "completed answer" }],
-        }),
-        live({
-          id: "u",
-          role: "user",
-          parts: [{ type: "text", text: "the new question" }],
-        }),
-      ],
-      isStreaming: true,
-      t,
-    });
-    expect(md).toContain("completed answer");
-    expect(md).not.toContain("still being generated");
-  });
-
-  it("emits the heading + note for a streaming tail assistant with empty parts", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ id: "u1", role: "user", content: "q" })],
-      live: [
-        live({ id: "u1", role: "user", parts: [{ type: "text", text: "q" }] }),
-        live({ id: "a-live", role: "assistant", parts: [] }),
-      ],
-      isStreaming: true,
-      t,
-    });
-    expect(md).toContain("## 2. AI agent");
-    expect(md).toContain("still being generated");
-  });
-});
-
-describe("buildChatMarkdown — live enrichment from persisted rows", () => {
-  it("pulls usage / error / timestamp from the persisted row matched by id", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          id: "a1",
-          role: "assistant",
-          content: "x",
-          createdAt: "2026-06-22T10:00:00.000Z",
-          metadata: {
-            usage: { inputTokens: 10, outputTokens: 5 },
-            error: "rate limited",
-          },
-        }),
-      ],
-      live: [
-        // Same id as the persisted row, but no usage/error/timestamp on the live msg.
-        live({
-          id: "a1",
-          role: "assistant",
-          parts: [{ type: "text", text: "reply" }],
-        }),
-      ],
-      isStreaming: false,
-      t,
-    });
-    expect(md).toContain("reply");
-    // Token footer + total come from the enriched row.
-    expect(md).toContain("_Tokens — in: 10, out: 5, total: 15_");
-    expect(md).toContain("- Total tokens: 15");
-    expect(md).toContain("**⚠️ Error:** rate limited");
-    // The persisted timestamp is carried into the export.
-    expect(md).toContain("<!-- 2026-06-22T10:00:00.000Z -->");
-  });
-
-  it("prefers authoritative usage already on the live message over the row's", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({
-          id: "a1",
-          role: "assistant",
-          content: "x",
-          metadata: {
-            usage: { inputTokens: 1, outputTokens: 1, totalTokens: 2 },
-          },
-        }),
-      ],
-      live: [
-        live({
-          id: "a1",
-          role: "assistant",
-          parts: [{ type: "text", text: "reply" }],
-          metadata: {
-            usage: { inputTokens: 100, outputTokens: 50, totalTokens: 150 },
-          },
-        }),
-      ],
-      isStreaming: false,
-      t,
-    });
-    // The live (authoritative, freshest) usage wins, not the stale row usage.
-    expect(md).toContain("- Total tokens: 150");
-    expect(md).not.toContain("- Total tokens: 2");
-  });
-
-  it("a current-turn live message with no matching row renders without a footer", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ id: "u1", role: "user", content: "q" })],
-      live: [
-        live({ id: "u1", role: "user", parts: [{ type: "text", text: "q" }] }),
-        live({
-          id: "a-live",
-          role: "assistant",
-          parts: [{ type: "text", text: "fresh reply" }],
-        }),
-      ],
-      isStreaming: false,
-      t,
-    });
-    expect(md).toContain("fresh reply");
-    // No persisted row for the live assistant -> no token footer, no timestamp.
-    expect(md).not.toContain("_Tokens —");
-    expect(md).not.toContain("<!-- undefined -->");
-  });
-});
-
-describe("buildChatMarkdown — fallback + banner", () => {
-  it("falls back to the persisted rows when there are no live messages", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [
-        row({ role: "user", content: "from rows" }),
-        row({
-          role: "assistant",
-          content: "answer",
-          metadata: { usage: { inputTokens: 4, outputTokens: 6 } },
-        }),
-      ],
-      live: [], // empty live mirror -> fallback path
-      isStreaming: false,
-      t,
-    });
-    expect(md).toContain("## 1. You");
-    expect(md).toContain("## 2. AI agent");
-    expect(md).toContain("from rows");
-    expect(md).toContain("- Messages: 2");
-    expect(md).toContain("- Total tokens: 10");
-  });
-
-  it("appends the on-screen banner once, after the messages", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ role: "user", content: "q" })],
-      live: [
-        live({ id: "u", role: "user", parts: [{ type: "text", text: "q" }] }),
-      ],
-      isStreaming: false,
-      banner: "Rate limit reached — try again shortly.",
-      t,
-    });
-    expect(md).toContain("_⚠️ Rate limit reached — try again shortly._");
-    // Banner comes after the (only) message block.
-    expect(md.indexOf("Rate limit reached")).toBeGreaterThan(
-      md.indexOf("## 1."),
-    );
-  });
-
-  it("omits the banner block when there is no banner", () => {
-    const md = buildChatMarkdown({
-      title: "t",
-      chatId: "c",
-      rows: [row({ role: "user", content: "q" })],
-      live: [
-        live({ id: "u", role: "user", parts: [{ type: "text", text: "q" }] }),
-      ],
-      isStreaming: false,
-      banner: null,
-      t,
-    });
-    expect(md).not.toContain("_⚠️");
-  });
-});
-
-// #174: a brand-new, not-yet-persisted chat whose first turn is streaming (or was
-// interrupted) has live messages but NO persisted rows yet, and its chat id is not
-// known (the caller passes a placeholder). The export must still capture the
-// on-screen thread WYSIWYG from the live messages alone.
-describe("buildChatMarkdown — first-turn export with no persisted base (#174)", () => {
-  it("builds the document from live messages alone when rows are empty", () => {
-    const md = buildChatMarkdown({
-      title: null,
-      chatId: "unsaved",
-      rows: [],
-      live: [
-        live({
-          id: "u1",
-          role: "user",
-          parts: [{ type: "text", text: "hello" }],
-        }),
-        live({
-          id: "a1",
-          role: "assistant",
-          parts: [{ type: "text", text: "partial reply" }],
-        }),
-      ],
-      isStreaming: true,
-      t,
-    });
-    // Both on-screen messages are serialized, numbered from 1.
-    expect(md).toContain("## 1. You");
-    expect(md).toContain("hello");
-    expect(md).toContain("## 2. AI agent");
-    expect(md).toContain("partial reply");
-    // The streaming tail assistant is flagged as in-progress.
-    expect(md).toContain("still being generated");
-    // The placeholder chat id and the live message count are recorded.
-    expect(md).toContain("- Chat ID: `unsaved`");
-    expect(md).toContain("- Messages: 2");
-    // No persisted timestamp exists for a current-turn live message.
-    expect(md).not.toContain("<!--");
-  });
-
-  it("captures an interrupted first turn (no rows, not streaming) without a generating note", () => {
-    const md = buildChatMarkdown({
-      title: null,
-      chatId: "unsaved",
-      rows: [],
-      live: [
-        live({ id: "u1", role: "user", parts: [{ type: "text", text: "q" }] }),
-        live({
-          id: "a1",
-          role: "assistant",
-          parts: [{ type: "text", text: "half an answer" }],
-        }),
-      ],
-      isStreaming: false,
-      banner: "Connection dropped — the response was cut off.",
-      t,
-    });
-    expect(md).toContain("half an answer");
-    // An interrupted (non-streaming) partial is exported as-is, no generating note.
-    expect(md).not.toContain("still being generated");
-    // The on-screen banner records the interruption.
-    expect(md).toContain("_⚠️ Connection dropped — the response was cut off._");
-  });
-});

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

@@ -1,308 +0,0 @@
-/**
- * Client-only Markdown builder for an AI agent chat. Serializes the already
- * persisted message rows (loaded via `useAiChatMessagesQuery`) into a single
- * 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 output is a technical artifact.
- */
-
-import type { IAiChatMessageRow } from "@/features/ai-chat/types/ai-chat.types.ts";
-import {
-  ToolUiPart,
-  getToolName,
-  toolRunState,
-  toolLabelKey,
-} from "@/features/ai-chat/utils/tool-parts.tsx";
-
-// Minimal translator signature compatible with react-i18next's `t`.
-type Translate = (key: string, values?: Record<string, unknown>) => string;
-
-interface BuildChatMarkdownArgs {
-  title: string | null;
-  chatId: string;
-  /** The live, on-screen messages — the WYSIWYG source of the export. When
-   *  present and non-empty these DRIVE the document (so it mirrors exactly what
-   *  the user sees, including a partial reply from an interrupted turn). Each is
-   *  matched to a persisted row by `id` to enrich it with token usage / error /
-   *  timestamp. When absent or empty the builder falls back to `rows`. */
-  live?: LiveMessage[];
-  /** Persisted message rows. Enrichment source (matched to `live` by id) AND the
-   *  fallback document source when `live` is empty. */
-  rows: IAiChatMessageRow[];
-  /** Whether the live thread is still streaming. Only then is the tail assistant
-   *  message flagged "still generating"; an interrupted (non-streaming) partial
-   *  reply is exported as-is and the `banner` explains the interruption. */
-  isStreaming?: boolean;
-  /** The on-screen banner text (error / dropped connection / manual stop),
-   *  appended at the end of the export so the artifact records the interruption
-   *  the user saw. */
-  banner?: string | null;
-  t: Translate;
-}
-
-/** A single AI SDK UIMessage part (text part or other). */
-interface TextLikePart {
-  type: string;
-  text?: string;
-}
-
-/** Authoritative per-turn usage the server attaches to a message / row. */
-interface UsageLike {
-  inputTokens?: number;
-  outputTokens?: number;
-  totalTokens?: number;
-  reasoningTokens?: number;
-}
-
-/** A live, on-screen message (subset of the AI SDK UIMessage we consume). */
-interface LiveMessage {
-  id: string;
-  role: "user" | "assistant" | string;
-  parts: TextLikePart[];
-  metadata?: { usage?: UsageLike; error?: string };
-}
-
-/** One message normalized for rendering, regardless of live/persisted origin. */
-interface ExportItem {
-  role: string;
-  parts: TextLikePart[];
-  usage?: UsageLike;
-  error?: string;
-  /** ISO timestamp from the persisted row, when one is known. */
-  createdAt?: string;
-  /** True only for the tail assistant message while the thread is streaming. */
-  generating: boolean;
-}
-
-/**
- * Stringify an arbitrary tool input/output value for a fenced block. Strings
- * pass through as-is; everything else is pretty-printed JSON, falling back to
- * `String(value)` if serialization throws (e.g. a circular structure).
- */
-function stringify(value: unknown): string {
-  if (typeof value === "string") return value;
-  try {
-    return JSON.stringify(value, null, 2);
-  } catch {
-    return String(value);
-  }
-}
-
-/**
- * Wrap `code` in a fenced code block whose backtick delimiter is LONGER than
- * the longest backtick run inside the content, so embedded backticks (or even
- * a literal ``` fence) never break out of the block. Minimum 3 backticks.
- */
-function fence(code: string, lang = ""): string {
-  const runs: string[] = code.match(/`+/g) ?? [];
-  const longest = runs.reduce((m, s) => Math.max(m, s.length), 0);
-  const delim = "`".repeat(Math.max(3, longest + 1));
-  return `${delim}${lang}\n${code}\n${delim}`;
-}
-
-/** Per-row token count, mirroring the header sum in ai-chat-window.tsx. */
-function rowTokens(usage: {
-  inputTokens?: number;
-  outputTokens?: number;
-  totalTokens?: number;
-  reasoningTokens?: number;
-}): number {
-  return (
-    usage.totalTokens ?? (usage.inputTokens ?? 0) + (usage.outputTokens ?? 0)
-  );
-}
-
-/** Render one message's UIMessage parts into an array of Markdown blocks
- *  (text blocks + tool blocks). Mirrors MessageItem's part handling. */
-function renderMessageParts(parts: TextLikePart[], t: Translate): string[] {
-  const out: string[] = [];
-
-  for (const part of parts) {
-    if (part.type === "text") {
-      const text = (part.text ?? "").trim();
-      // Skip empty/whitespace-only text parts (matches MessageItem).
-      if (text.length > 0) out.push(text);
-      continue;
-    }
-
-    const isToolPart =
-      part.type.startsWith("tool-") || part.type === "dynamic-tool";
-    if (!isToolPart) continue;
-
-    const tp = part as unknown as ToolUiPart;
-    const name = getToolName(tp);
-    const { key, values } = toolLabelKey(name);
-    const label = t(key, values);
-    const state = toolRunState(tp.state);
-
-    const toolLines: string[] = [
-      `**Tool: ${label}** (\`${name}\`) — ${state}`,
-    ];
-    if (tp.input !== undefined) {
-      toolLines.push("Input:");
-      toolLines.push(fence(stringify(tp.input), "json"));
-    }
-    if (tp.output !== undefined) {
-      toolLines.push("Output:");
-      toolLines.push(fence(stringify(tp.output), "json"));
-    }
-    if (tp.errorText) {
-      toolLines.push(`**Error:** ${tp.errorText}`);
-    }
-    out.push(toolLines.join("\n\n"));
-  }
-
-  return out;
-}
-
-/** Resolve a persisted row's parts: prefer the rich persisted parts, else a
- *  single text part built from the plain-text content (mirrors `rowToUiMessage`). */
-function rowParts(row: IAiChatMessageRow): TextLikePart[] {
-  return Array.isArray(row.metadata?.parts) && row.metadata.parts.length > 0
-    ? (row.metadata.parts as TextLikePart[])
-    : [{ type: "text", text: row.content ?? "" }];
-}
-
-/**
- * Normalize the export to one ordered list of {@link ExportItem}, WYSIWYG-first:
- *
- * - When `live` messages are present, THEY are the document (what the user sees,
- *   incl. an interrupted turn's partial reply). Each is matched to a persisted
- *   row by `id` to pull token usage / error / timestamp — a live message of the
- *   CURRENT turn has no matching row yet, so it simply renders without a footer.
- *   Authoritative `usage`/`error` already on the live message metadata win over
- *   the row (the server attaches usage to the streamed message at a step
- *   boundary before the row is refetched). Only the tail assistant message is
- *   flagged `generating`, and only while `isStreaming`.
- * - When `live` is empty (e.g. the export runs before the live mirror is
- *   populated), fall back to the persisted `rows` so the format never regresses.
- */
-function resolveItems(
-  live: LiveMessage[] | undefined,
-  rows: IAiChatMessageRow[],
-  isStreaming: boolean,
-): ExportItem[] {
-  if (live && live.length > 0) {
-    const rowsById = new Map(rows.map((r) => [r.id, r]));
-    // The "still generating" note may apply ONLY to an assistant message that is
-    // the actual TAIL of the list — that is where the on-screen typing indicator
-    // sits. While `status === "submitted"` (isStreaming true) right after the
-    // user hit send, the tail is the USER message and the new assistant turn has
-    // no message yet; the previous assistant answer is shown complete on screen,
-    // so it must NOT be flagged (the indicator renders as a separate bottom
-    // block, not on that answer).
-    const lastIndex = live.length - 1;
-    const tailIsStreamingAssistant =
-      isStreaming && live[lastIndex]?.role === "assistant";
-    return live.map((m, i) => {
-      const row = rowsById.get(m.id);
-      return {
-        role: m.role,
-        parts: m.parts ?? [],
-        // Authoritative usage/error already on the live message (the server
-        // attaches usage to the streamed message at a step boundary) wins over
-        // the persisted row; a current-turn live message has no matching row yet
-        // and simply renders without a token footer (the accepted WYSIWYG
-        // tradeoff — an interrupted turn loses only its token footer, not text).
-        usage: m.metadata?.usage ?? row?.metadata?.usage,
-        error: m.metadata?.error ?? row?.metadata?.error ?? undefined,
-        createdAt: row?.createdAt,
-        generating: tailIsStreamingAssistant && i === lastIndex,
-      };
-    });
-  }
-
-  return rows.map((row) => ({
-    role: row.role,
-    parts: rowParts(row),
-    usage: row.metadata?.usage,
-    error: row.metadata?.error ?? undefined,
-    createdAt: row.createdAt,
-    generating: false,
-  }));
-}
-
-/**
- * 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: BuildChatMarkdownArgs): string {
-  const { title, chatId, live, rows, isStreaming, banner, t } = args;
-  const blocks: string[] = [];
-
-  const items = resolveItems(live, rows, isStreaming === true);
-
-  const heading = (title ?? "").trim() || t("Untitled chat");
-  blocks.push(`# ${heading}`);
-
-  // Metadata bullet list. Total tokens is only shown when there is a sum.
-  const totalTokens = items.reduce(
-    (sum, item) => (item.usage ? sum + rowTokens(item.usage) : sum),
-    0,
-  );
-  const meta = [
-    `- Chat ID: \`${chatId}\``,
-    `- Exported: ${new Date().toISOString()}`,
-    `- Messages: ${items.length}`,
-  ];
-  if (totalTokens > 0) meta.push(`- Total tokens: ${totalTokens}`);
-  blocks.push(meta.join("\n"));
-
-  items.forEach((item, index) => {
-    blocks.push("---");
-
-    const roleLabel = item.role === "assistant" ? t("AI agent") : t("You");
-    blocks.push(`## ${index + 1}. ${roleLabel}`);
-
-    // Created-at kept in source as an HTML comment (out of the rendered prose).
-    // A live message of the current turn has no persisted row yet — omit it.
-    if (item.createdAt) blocks.push(`<!-- ${item.createdAt} -->`);
-
-    blocks.push(...renderMessageParts(item.parts, t));
-
-    // A generating assistant may have empty/no parts yet — the heading (above)
-    // and this note still record the in-progress turn.
-    if (item.generating) {
-      blocks.push(
-        "_⏳ This message is still being generated — the export captured a partial, in-progress response._",
-      );
-    }
-
-    // A persisted per-message error (the raw provider text) may coexist with the
-    // trailing `banner` (the classified on-screen alert) when the failed turn's
-    // row has already been refetched by export time. They describe the same
-    // failure at different fidelity; showing both is an accepted, minor redundancy.
-    if (item.error) {
-      blocks.push(`**⚠️ Error:** ${item.error}`);
-    }
-
-    const usage = item.usage;
-    if (usage) {
-      const total = usage.totalTokens ?? rowTokens(usage);
-      // Reasoning (thinking) tokens are shown only when the provider reported a
-      // positive count; old rows / non-reasoning providers omit it.
-      const reasoning =
-        usage.reasoningTokens && usage.reasoningTokens > 0
-          ? `, reasoning: ${usage.reasoningTokens}`
-          : "";
-      blocks.push(
-        `_Tokens — in: ${usage.inputTokens ?? "?"}, out: ${usage.outputTokens ?? "?"}${reasoning}, total: ${total}_`,
-      );
-    }
-  });
-
-  // Record the on-screen banner (error / dropped connection / manual stop) so
-  // the export reflects exactly what the user saw, including an interruption.
-  if (banner && banner.trim().length > 0) {
-    blocks.push("---");
-    blocks.push(`_⚠️ ${banner.trim()}_`);
-  }
-
-  // Blank line between blocks so the Markdown renders cleanly.
-  return blocks.join("\n\n");
-}

apps/server/package.json

@@ -11,7 +11,7 @@
     "start": "cross-env NODE_ENV=development nest start",
     "start:dev": "cross-env NODE_ENV=development nest start --watch",
     "start:debug": "cross-env NODE_ENV=development nest start --debug --watch",
-    "start:prod": "cross-env NODE_ENV=production node dist/main",
+    "start:prod": "cross-env NODE_ENV=production node --heapsnapshot-near-heap-limit=2 dist/main",
     "collab:prod": "cross-env NODE_ENV=production node dist/collaboration/server/collab-main",
     "collab:dev": "cross-env NODE_ENV=development node dist/collaboration/server/collab-main",
     "email:dev": "email dev -p 5019 -d ./src/integrations/transactional/emails",

apps/server/src/core/ai-chat/ai-chat.controller.export.spec.ts

@@ -0,0 +1,159 @@
+import { ForbiddenException } from '@nestjs/common';
+import { AiChatController } from './ai-chat.controller';
+import {
+  planFinalizeAssistant,
+  applyFinalize,
+  flushAssistant,
+  type AssistantFlush,
+} from './ai-chat.service';
+import type { User, Workspace } from '@docmost/db/types/entity.types';
+
+/**
+ * Wiring spec for the #183 `POST /ai-chat/export` endpoint. It must: own-gate via
+ * the chat lookup (workspace-scoped + creator-owned), load the FULL transcript
+ * via findAllByChat, render server-side, and return `{ markdown }`. Exercised by
+ * instantiating the controller with hand-rolled mocks — no Nest graph, no DB.
+ */
+describe('AiChatController.export', () => {
+  const user = { id: 'u1' } as User;
+  const workspace = { id: 'ws1' } as Workspace;
+
+  function makeController(
+    over: {
+      chat?: unknown;
+      rows?: unknown[];
+    } = {},
+  ) {
+    const chat =
+      'chat' in over
+        ? over.chat
+        : { id: 'c1', creatorId: 'u1', title: 'My chat' };
+    const aiChatRepo = {
+      findById: jest.fn().mockResolvedValue(chat),
+    };
+    const aiChatMessageRepo = {
+      findAllByChat: jest.fn().mockResolvedValue(
+        over.rows ?? [
+          {
+            id: 'm1',
+            role: 'user',
+            content: 'hi',
+            metadata: null,
+            status: null,
+          },
+          {
+            id: 'm2',
+            role: 'assistant',
+            content: 'hello',
+            metadata: null,
+            status: 'completed',
+          },
+        ],
+      ),
+    };
+    const controller = new AiChatController(
+      {} as never,
+      aiChatRepo as never,
+      aiChatMessageRepo as never,
+      {} as never,
+    );
+    return { controller, aiChatRepo, aiChatMessageRepo };
+  }
+
+  it('renders the full transcript and returns { markdown }', async () => {
+    const { controller, aiChatMessageRepo } = makeController();
+    const res = await controller.export({ chatId: 'c1' }, user, workspace);
+    expect(aiChatMessageRepo.findAllByChat).toHaveBeenCalledWith('c1', 'ws1');
+    expect(res.markdown).toContain('# My chat');
+    expect(res.markdown).toContain('## 1. You');
+    expect(res.markdown).toContain('## 2. AI agent');
+  });
+
+  it('forbids a chat the user does not own', async () => {
+    const { controller } = makeController({
+      chat: { id: 'c1', creatorId: 'someone-else', title: 'X' },
+    });
+    await expect(
+      controller.export({ chatId: 'c1' }, user, workspace),
+    ).rejects.toBeInstanceOf(ForbiddenException);
+  });
+
+  it('forbids a missing / foreign-workspace chat', async () => {
+    const { controller } = makeController({ chat: null });
+    await expect(
+      controller.export({ chatId: 'c1' }, user, workspace),
+    ).rejects.toBeInstanceOf(ForbiddenException);
+  });
+
+  it('localizes labels when lang=ru is passed', async () => {
+    const { controller } = makeController();
+    const res = await controller.export(
+      { chatId: 'c1', lang: 'ru' },
+      user,
+      workspace,
+    );
+    expect(res.markdown).toContain('## 1. Вы');
+    expect(res.markdown).toContain('## 2. ИИ-агент');
+  });
+});
+
+/**
+ * The terminal-finalize dispatch (#183): the assistant row is INSERTed upfront
+ * as 'streaming' and finalized once on the terminal callback. When the upfront
+ * insert SUCCEEDED (we hold an id) finalize UPDATEs that row; when it FAILED
+ * (assistantId is undefined) finalize falls back to INSERTing the terminal row
+ * so the turn is not lost — the only safety against losing the turn entirely.
+ *
+ * `planFinalizeAssistant` is the pure decision; `applyFinalize` is the REAL
+ * dispatch the service uses, exercised here over a mock repo (not a copy of the
+ * logic) so a production drift would fail the test (#186 review).
+ */
+describe('finalizeAssistant dispatch (planFinalizeAssistant + applyFinalize)', () => {
+  const workspaceId = 'ws1';
+
+  // Drive the SAME applyFinalize the service calls (no duplicated logic).
+  async function dispatchFinalize(
+    repo: { insert: jest.Mock; update: jest.Mock },
+    assistantId: string | undefined,
+    flushed: AssistantFlush,
+  ): Promise<void> {
+    await applyFinalize(
+      repo,
+      planFinalizeAssistant(assistantId),
+      { chatId: 'c1', workspaceId, userId: 'u1' },
+      flushed,
+    );
+  }
+
+  it('plan: update when the upfront insert returned an id', () => {
+    expect(planFinalizeAssistant('a1')).toEqual({ kind: 'update', id: 'a1' });
+  });
+
+  it('plan: insert (fallback) when there is no upfront id', () => {
+    expect(planFinalizeAssistant(undefined)).toEqual({ kind: 'insert' });
+  });
+
+  it('(a) upfront insert succeeded -> finalize UPDATEs the row by id', async () => {
+    const repo = { insert: jest.fn(), update: jest.fn() };
+    const flushed = flushAssistant([], 'final answer', 'completed', {
+      finishReason: 'stop',
+    });
+    await dispatchFinalize(repo, 'a1', flushed);
+    expect(repo.update).toHaveBeenCalledWith('a1', workspaceId, flushed);
+    expect(repo.insert).not.toHaveBeenCalled();
+  });
+
+  it('(b) upfront insert failed -> finalize INSERTs the terminal payload', async () => {
+    const repo = { insert: jest.fn(), update: jest.fn() };
+    const flushed = flushAssistant([], 'partial', 'error', { error: 'boom' });
+    await dispatchFinalize(repo, undefined, flushed);
+    expect(repo.update).not.toHaveBeenCalled();
+    expect(repo.insert).toHaveBeenCalledTimes(1);
+    const arg = repo.insert.mock.calls[0][0];
+    // The fallback insert carries the terminal content/status/metadata.
+    expect(arg.role).toBe('assistant');
+    expect(arg.content).toBe('partial');
+    expect(arg.status).toBe('error');
+    expect((arg.metadata as { error?: string }).error).toBe('boom');
+  });
+});

apps/server/src/core/ai-chat/ai-chat.controller.ts

@@ -20,7 +20,7 @@ import { JwtAuthGuard } from '../../common/guards/jwt-auth.guard';
 import { AuthUser } from '../../common/decorators/auth-user.decorator';
 import { AuthWorkspace } from '../../common/decorators/auth-workspace.decorator';
 import { SkipTransform } from '../../common/decorators/skip-transform.decorator';
-import { User, Workspace } from '@docmost/db/types/entity.types';
+import { AiChat, User, Workspace } from '@docmost/db/types/entity.types';
 import { PaginationOptions } from '@docmost/db/pagination/pagination-options';
 import { AiChatRepo } from '@docmost/db/repos/ai-chat/ai-chat.repo';
 import { AiChatMessageRepo } from '@docmost/db/repos/ai-chat/ai-chat-message.repo';
@@ -31,10 +31,12 @@ import { AiChatService, AiChatStreamBody } from './ai-chat.service';
 import { AiTranscriptionService } from './ai-transcription.service';
 import {
   ChatIdDto,
+  ExportChatDto,
   GetChatMessagesDto,
   RenameChatDto,
 } from './dto/ai-chat.dto';
 import { describeProviderError } from '../../integrations/ai/ai-error.util';
+import { buildChatMarkdown } from './chat-markdown.util';
 
 /**
  * Per-user AI chat API (§6.1). Routes are POST to match this codebase's
@@ -81,6 +83,36 @@ export class AiChatController {
     );
   }
 
+  /**
+   * Export a chat to Markdown (#183). The DB is the single source of truth: the
+   * whole transcript is loaded (oldest -> newest) and rendered server-side. Now
+   * that the assistant row is persisted upfront and per step, an interrupted
+   * turn is included up to its last finished step. Workspace-scoped and owner-
+   * gated via assertOwnedChat (same as the other read endpoints). Returns
+   * `{ markdown }`. `lang` localizes the few fixed labels (default English).
+   */
+  @HttpCode(HttpStatus.OK)
+  @Post('export')
+  async export(
+    @Body() dto: ExportChatDto,
+    @AuthUser() user: User,
+    @AuthWorkspace() workspace: Workspace,
+  ): Promise<{ markdown: string }> {
+    const chat = await this.assertOwnedChat(dto.chatId, user, workspace);
+    const rows = await this.aiChatMessageRepo.findAllByChat(
+      dto.chatId,
+      workspace.id,
+    );
+    const markdown = buildChatMarkdown({
+      title: chat.title ?? null,
+      chatId: dto.chatId,
+      rows,
+      // normalizeLang(undefined) already yields 'en', so no `?? 'en'` is needed.
+      lang: dto.lang,
+    });
+    return { markdown };
+  }
+
   /** Rename a chat. */
   @HttpCode(HttpStatus.OK)
   @Post('rename')
@@ -90,7 +122,11 @@ export class AiChatController {
     @AuthWorkspace() workspace: Workspace,
   ) {
     await this.assertOwnedChat(dto.chatId, user, workspace);
-    await this.aiChatRepo.update(dto.chatId, { title: dto.title }, workspace.id);
+    await this.aiChatRepo.update(
+      dto.chatId,
+      { title: dto.title },
+      workspace.id,
+    );
     return { success: true };
   }
 
@@ -145,7 +181,10 @@ export class AiChatController {
     // Resolve the agent role for this turn BEFORE hijack: existing chats read it
     // from ai_chats.role_id (authoritative), a new chat from body.roleId. The
     // role drives both the persona and the optional model override below.
-    const role = await this.aiChatService.resolveRoleForRequest(workspace, body);
+    const role = await this.aiChatService.resolveRoleForRequest(
+      workspace,
+      body,
+    );
 
     // Resolve the model (applying the role's optional override) BEFORE hijack so
     // an unconfigured provider — including a role pointing at an unconfigured
@@ -232,7 +271,9 @@ export class AiChatController {
     let file = null;
     try {
       // Whisper hard-caps uploads at 25MB; allow a single file.
-      file = await req.file({ limits: { fileSize: 25 * 1024 * 1024, files: 1 } });
+      file = await req.file({
+        limits: { fileSize: 25 * 1024 * 1024, files: 1 },
+      });
     } catch (err: any) {
       if (err?.statusCode === 413) {
         throw new BadRequestException('Audio file too large (max 25MB)');
@@ -283,11 +324,12 @@ export class AiChatController {
     chatId: string,
     user: User,
     workspace: Workspace,
-  ): Promise<void> {
+  ): Promise<AiChat> {
     const chat = await this.aiChatRepo.findById(chatId, workspace.id);
     if (!chat || chat.creatorId !== user.id) {
       throw new ForbiddenException();
     }
+    return chat;
   }
 }
 

apps/server/src/core/ai-chat/ai-chat.service.lifecycle.spec.ts

@@ -0,0 +1,61 @@
+import { Logger } from '@nestjs/common';
+import { AiChatService } from './ai-chat.service';
+
+/**
+ * Lifecycle unit tests for AiChatService.onModuleInit (#183 crash-recovery
+ * sweep). The sweep is BEST-EFFORT: a failure must be logged (warn) but must
+ * NEVER throw out of onModuleInit and block server startup. Exercised with a
+ * hand-rolled mock repo — no Nest graph, no DB. Only `aiChatMessageRepo` is
+ * touched by onModuleInit, so the other constructor deps are stubbed as never.
+ */
+describe('AiChatService.onModuleInit (startup sweep)', () => {
+  function makeService(sweepStreaming: jest.Mock) {
+    const aiChatMessageRepo = { sweepStreaming };
+    const service = new AiChatService(
+      {} as never, // ai
+      {} as never, // aiChatRepo
+      aiChatMessageRepo as never,
+      {} as never, // aiSettings
+      {} as never, // tools
+      {} as never, // mcpClients
+      {} as never, // aiAgentRoleRepo
+      {} as never, // pageRepo
+      {} as never, // pageAccess
+    );
+    return { service, aiChatMessageRepo };
+  }
+
+  afterEach(() => jest.restoreAllMocks());
+
+  it('happy path: calls sweepStreaming and resolves', async () => {
+    const sweepStreaming = jest.fn().mockResolvedValue(0);
+    const { service } = makeService(sweepStreaming);
+    await expect(service.onModuleInit()).resolves.toBeUndefined();
+    expect(sweepStreaming).toHaveBeenCalledTimes(1);
+  });
+
+  it('logs how many rows were swept when > 0', async () => {
+    const sweepStreaming = jest.fn().mockResolvedValue(3);
+    const logSpy = jest
+      .spyOn(Logger.prototype, 'log')
+      .mockImplementation(() => undefined);
+    const { service } = makeService(sweepStreaming);
+    await service.onModuleInit();
+    expect(logSpy).toHaveBeenCalledTimes(1);
+    expect(String(logSpy.mock.calls[0][0])).toContain('3');
+  });
+
+  it('sweepStreaming throws -> onModuleInit resolves (does NOT throw) and warns', async () => {
+    const sweepStreaming = jest
+      .fn()
+      .mockRejectedValue(new Error('db unavailable'));
+    const warnSpy = jest
+      .spyOn(Logger.prototype, 'warn')
+      .mockImplementation(() => undefined);
+    const { service } = makeService(sweepStreaming);
+    // Must not throw — a sweep failure may never block startup.
+    await expect(service.onModuleInit()).resolves.toBeUndefined();
+    expect(warnSpy).toHaveBeenCalledTimes(1);
+    expect(String(warnSpy.mock.calls[0][0])).toContain('db unavailable');
+  });
+});

apps/server/src/core/ai-chat/ai-chat.service.spec.ts

@@ -4,7 +4,7 @@ import {
   serializeSteps,
   rowToUiMessage,
   prepareAgentStep,
-  buildPartialAssistantRecord,
+  flushAssistant,
   chatStreamMetadata,
   accumulateStepUsage,
   MAX_AGENT_STEPS,
@@ -94,8 +94,12 @@ describe('assistantParts', () => {
     const steps = [
       {
         text: '',
-        toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: { id: 'p1' } }],
-        toolResults: [{ toolCallId: 'c1', toolName: 'getPage', output: { title: 'T' } }],
+        toolCalls: [
+          { toolCallId: 'c1', toolName: 'getPage', input: { id: 'p1' } },
+        ],
+        toolResults: [
+          { toolCallId: 'c1', toolName: 'getPage', output: { title: 'T' } },
+        ],
       },
     ];
     const parts = assistantParts(steps, '') as AnyPart[];
@@ -109,7 +113,9 @@ describe('assistantParts', () => {
     const steps = [
       {
         text: '',
-        toolCalls: [{ toolCallId: 'c9', toolName: 'insertNode', input: { node: {} } }],
+        toolCalls: [
+          { toolCallId: 'c9', toolName: 'insertNode', input: { node: {} } },
+        ],
         toolResults: [],
       },
     ];
@@ -136,7 +142,8 @@ describe('assistantParts', () => {
     ];
     const parts = assistantParts(steps, '') as AnyPart[];
     const toolParts = parts.filter(
-      (p) => typeof p.type === 'string' && (p.type as string).startsWith('tool-'),
+      (p) =>
+        typeof p.type === 'string' && (p.type as string).startsWith('tool-'),
     );
     expect(toolParts).toHaveLength(0);
   });
@@ -222,79 +229,108 @@ describe('prepareAgentStep', () => {
     // The synthesis instruction is appended.
     expect(result?.system).toContain(FINAL_STEP_INSTRUCTION);
   });
-
-  it('pins the off-by-one boundary (MAX-2 is not final, MAX-1 is)', () => {
-    // Boundary expressed via the constant, not a hardcoded 18/19, so the test
-    // tracks MAX_AGENT_STEPS if the cap ever changes.
-    expect(prepareAgentStep(MAX_AGENT_STEPS - 2, 'SYS')).toBeUndefined();
-    const atBoundary = prepareAgentStep(MAX_AGENT_STEPS - 1, 'SYS');
-    expect(atBoundary).toBeDefined();
-    expect(atBoundary?.toolChoice).toBe('none');
-  });
 });
 
 /**
- * Unit test for buildPartialAssistantRecord: the pure helper that shapes the
- * assistant-message record persisted on a partial/failed turn (the streamText
- * onError / onAbort paths). It captures the PARTIAL answer the user already saw
- * (finished steps' text + tool parts, plus the in-progress step's text) so a
- * provider error / disconnect no longer throws the streamed answer away. Pinning
- * the record shape here covers the persist-partial logic without seaming
- * streamText itself.
+ * flushAssistant (#183): the PURE row builder behind the step-granular durable
+ * write path. It runs identically for the upfront insert (empty steps,
+ * 'streaming'), every per-step update, and the terminal finalize — so a future
+ * background worker can call the same function. These tests pin the four status
+ * shapes and the `metadata.parts` shape that rowToUiMessage/findRecent depend on
+ * (per-step text + tool parts via assistantParts, in-progress text appended).
  */
-describe('buildPartialAssistantRecord', () => {
+describe('flushAssistant', () => {
   type AnyPart = Record<string, unknown>;
 
-  it('records an empty turn with the error text (preserves old behavior)', () => {
-    const rec = buildPartialAssistantRecord([], '', 'error', '401: Unauthorized');
-    expect(rec).toEqual({
-      text: '',
-      toolCalls: null,
-      metadata: { finishReason: 'error', parts: [], error: '401: Unauthorized' },
-    });
-  });
-
-  it('persists in-progress text (no finished steps) as the partial answer', () => {
-    const rec = buildPartialAssistantRecord([], 'partial answer', 'error', 'boom');
-    expect(rec.text).toBe('partial answer');
-    expect(rec.metadata.parts).toEqual([
-      { type: 'text', text: 'partial answer' },
-    ]);
-    expect(rec.metadata.error).toBe('boom');
-  });
-
-  it('combines a finished tool step with trailing in-progress text', () => {
-    const steps = [
-      {
+  const toolStep = {
     text: 'looked it up',
-        toolCalls: [
-          { toolCallId: 'c1', toolName: 'getPage', input: { id: 'p1' } },
-        ],
+    toolCalls: [{ toolCallId: 'c1', toolName: 'getPage', input: { id: 'p1' } }],
     toolResults: [
       { toolCallId: 'c1', toolName: 'getPage', output: { title: 'T' } },
     ],
-      },
-    ];
-    const rec = buildPartialAssistantRecord(steps, ' and then', 'error', 'boom');
-    const parts = rec.metadata.parts as AnyPart[];
-    // The finished step's text part is present.
-    expect(parts).toContainEqual({ type: 'text', text: 'looked it up' });
-    // The paired tool call+result becomes an output-available part.
-    const toolPart = parts.find((p) => p.type === 'tool-getPage');
-    expect(toolPart).toBeDefined();
-    expect(toolPart!.state).toBe('output-available');
-    // The in-progress text is appended LAST so the parts match the stream order.
-    expect(parts[parts.length - 1]).toEqual({ type: 'text', text: ' and then' });
-    expect(rec.text).toBe('looked it up and then');
-    expect(rec.toolCalls).not.toBeNull();
-    expect(rec.metadata.error).toBe('boom');
+  };
+
+  it('upfront seed: empty streaming row (no content, no toolCalls, empty parts)', () => {
+    const f = flushAssistant([], '', 'streaming');
+    expect(f.status).toBe('streaming');
+    expect(f.content).toBe('');
+    expect(f.toolCalls).toBeNull();
+    expect(f.metadata.parts).toEqual([]);
+    // No finishReason while streaming (it is not a terminal state).
+    expect('finishReason' in f.metadata).toBe(false);
   });
 
-  it('omits the error key on the abort path (no errorText)', () => {
-    const rec = buildPartialAssistantRecord([], 'half', 'aborted');
-    expect(rec.metadata.finishReason).toBe('aborted');
-    expect('error' in rec.metadata).toBe(false);
-    expect(rec.text).toBe('half');
+  it('streaming update folds in finished steps but keeps status streaming', () => {
+    const f = flushAssistant([toolStep], '', 'streaming');
+    expect(f.status).toBe('streaming');
+    expect(f.content).toBe('looked it up');
+    const parts = f.metadata.parts as AnyPart[];
+    expect(parts).toContainEqual({ type: 'text', text: 'looked it up' });
+    const toolPart = parts.find((p) => p.type === 'tool-getPage');
+    expect(toolPart!.state).toBe('output-available');
+    expect(f.toolCalls).not.toBeNull();
+  });
+
+  it('completed: attaches finishReason + normalized usage + contextTokens', () => {
+    const f = flushAssistant([toolStep], '', 'completed', {
+      finishReason: 'stop',
+      usage: { inputTokens: 10, outputTokens: 5, totalTokens: 15 },
+      contextTokens: 15,
+    });
+    expect(f.status).toBe('completed');
+    expect(f.metadata.finishReason).toBe('stop');
+    expect(f.metadata.usage).toEqual({
+      inputTokens: 10,
+      outputTokens: 5,
+      totalTokens: 15,
+      reasoningTokens: undefined,
+    });
+    expect(f.metadata.contextTokens).toBe(15);
+  });
+
+  it('error: records the error and a derived finishReason', () => {
+    const f = flushAssistant([], 'partial answer', 'error', { error: 'boom' });
+    expect(f.status).toBe('error');
+    expect(f.content).toBe('partial answer');
+    expect(f.metadata.error).toBe('boom');
+    // Derives finishReason from the terminal status when none is supplied.
+    expect(f.metadata.finishReason).toBe('error');
+    expect(f.metadata.parts).toEqual([
+      { type: 'text', text: 'partial answer' },
+    ]);
+  });
+
+  it('aborted: in-progress text appended last, no error key', () => {
+    const f = flushAssistant([toolStep], ' and then', 'aborted');
+    expect(f.status).toBe('aborted');
+    expect(f.metadata.finishReason).toBe('aborted');
+    expect('error' in f.metadata).toBe(false);
+    expect(f.content).toBe('looked it up and then');
+    const parts = f.metadata.parts as AnyPart[];
+    expect(parts[parts.length - 1]).toEqual({
+      type: 'text',
+      text: ' and then',
+    });
+  });
+
+  it('combines a finished tool step with trailing in-progress text (error path)', () => {
+    // The error path captures the PARTIAL answer the user already saw: each
+    // finished step's text + tool parts, then the in-progress step's text last.
+    const flushed = flushAssistant([toolStep], ' and then', 'error', {
+      error: 'boom',
+    });
+    const parts = flushed.metadata.parts as AnyPart[];
+    expect(parts).toContainEqual({ type: 'text', text: 'looked it up' });
+    const toolPart = parts.find((p) => p.type === 'tool-getPage');
+    expect(toolPart!.state).toBe('output-available');
+    // In-progress text appended LAST so the parts match the stream order.
+    expect(parts[parts.length - 1]).toEqual({
+      type: 'text',
+      text: ' and then',
+    });
+    expect(flushed.content).toBe('looked it up and then');
+    expect(flushed.toolCalls).not.toBeNull();
+    expect(flushed.metadata.error).toBe('boom');
   });
 });
 
@@ -319,10 +355,20 @@ describe('chatStreamMetadata', () => {
       chatStreamMetadata(
         { type: 'finish-step', usage: { outputTokens: 100 } },
         'chat-1',
-        { inputTokens: 500, outputTokens: 220, totalTokens: 720, reasoningTokens: 30 },
+        {
+          inputTokens: 500,
+          outputTokens: 220,
+          totalTokens: 720,
+          reasoningTokens: 30,
+        },
       ),
     ).toEqual({
-      usage: { inputTokens: 500, outputTokens: 220, totalTokens: 720, reasoningTokens: 30 },
+      usage: {
+        inputTokens: 500,
+        outputTokens: 220,
+        totalTokens: 720,
+        reasoningTokens: 30,
+      },
     });
   });
 
@@ -394,8 +440,18 @@ describe('accumulateStepUsage', () => {
   it('sums every field across two steps', () => {
     expect(
       accumulateStepUsage(
-        { inputTokens: 500, outputTokens: 100, totalTokens: 600, reasoningTokens: 30 },
-        { inputTokens: 520, outputTokens: 80, totalTokens: 600, reasoningTokens: 10 },
+        {
+          inputTokens: 500,
+          outputTokens: 100,
+          totalTokens: 600,
+          reasoningTokens: 30,
+        },
+        {
+          inputTokens: 520,
+          outputTokens: 80,
+          totalTokens: 600,
+          reasoningTokens: 10,
+        },
       ),
     ).toEqual({
       inputTokens: 1020,

apps/server/src/core/ai-chat/ai-chat.service.ts

@@ -1,4 +1,9 @@
-import { ForbiddenException, Injectable, Logger } from '@nestjs/common';
+import {
+  ForbiddenException,
+  Injectable,
+  Logger,
+  OnModuleInit,
+} from '@nestjs/common';
 import { FastifyReply } from 'fastify';
 import {
   streamText,
@@ -60,7 +65,10 @@ export function prepareAgentStep(
   system: string,
 ): { toolChoice: 'none'; system: string } | undefined {
   if (stepNumber >= MAX_AGENT_STEPS - 1) {
-    return { toolChoice: 'none', system: `${system}\n\n${FINAL_STEP_INSTRUCTION}` };
+    return {
+      toolChoice: 'none',
+      system: `${system}\n\n${FINAL_STEP_INSTRUCTION}`,
+    };
   }
   return undefined;
 }
@@ -121,7 +129,7 @@ export interface AiChatStreamArgs {
  *                    can be rebuilt for `convertToModelMessages`.
  */
 @Injectable()
-export class AiChatService {
+export class AiChatService implements OnModuleInit {
   private readonly logger = new Logger(AiChatService.name);
 
   constructor(
@@ -136,6 +144,32 @@ export class AiChatService {
     private readonly pageAccess: PageAccessService,
   ) {}
 
+  /**
+   * Crash-recovery sweep on server start (#183): any assistant row left in the
+   * 'streaming' state is the relic of a turn whose process died before it
+   * reached a terminal status. Flip those to 'aborted' so history/export show
+   * them settled (with whatever finished steps were already persisted) instead
+   * of perpetually "streaming". Best-effort: a sweep failure is logged but must
+   * never block server startup.
+   */
+  async onModuleInit(): Promise<void> {
+    try {
+      const swept = await this.aiChatMessageRepo.sweepStreaming();
+      if (swept > 0) {
+        this.logger.log(
+          `Startup sweep: marked ${swept} dangling 'streaming' assistant ` +
+            `message(s) as 'aborted'.`,
+        );
+      }
+    } catch (err) {
+      this.logger.warn(
+        `Startup sweep of dangling 'streaming' messages failed: ${
+          err instanceof Error ? err.message : 'unknown error'
+        }`,
+      );
+    }
+  }
+
   /**
    * Resolve the agent role that applies to this stream request, scoped to the
    * workspace and soft-delete aware. For an EXISTING chat the role is read from
@@ -259,9 +293,7 @@ export class AiChatService {
       content: incomingText,
       // jsonb column: UIMessage parts are JSON-serializable at runtime but not
       // structurally `JsonValue`, so cast through unknown.
-      metadata: (incoming?.parts
-        ? { parts: incoming.parts }
-        : null) as never,
+      metadata: (incoming?.parts ? { parts: incoming.parts } : null) as never,
     });
 
     // Rebuild the conversation from persisted history (not the client payload),
@@ -347,31 +379,6 @@ export class AiChatService {
       );
     };
 
-    // Persist the assistant message. Used by onFinish (full result) and the
-    // abort/error paths (partial result). Guarded so we persist at most once.
-    let persisted = false;
-    const persistAssistant = async (data: {
-      text: string;
-      toolCalls: unknown;
-      metadata: Record<string, unknown>;
-    }): Promise<void> => {
-      if (persisted) return;
-      persisted = true;
-      try {
-        await this.aiChatMessageRepo.insert({
-          chatId,
-          workspaceId: workspace.id,
-          userId: user.id,
-          role: 'assistant',
-          content: data.text ?? '',
-          toolCalls: (data.toolCalls ?? null) as never,
-          metadata: data.metadata as never,
-        });
-      } catch (err) {
-        this.logger.error('Failed to persist assistant message', err as Error);
-      }
-    };
-
     // Accumulate the turn's streamed output so a provider error / disconnect can
     // persist the PARTIAL answer the user already saw — the SDK's onError/onAbort
     // callbacks don't hand us the in-progress text. `capturedSteps` holds finished
@@ -380,6 +387,101 @@ export class AiChatService {
     const capturedSteps: StepLike[] = [];
     let inProgressText = '';
 
+    // Step-granular durability (#183): create the assistant row UPFRONT in the
+    // 'streaming' state (before any token), then UPDATE it as each step finishes
+    // and finalize it once on the terminal callback. If the process dies
+    // mid-turn the row survives with every finished step already persisted; the
+    // startup sweep (sweepStreaming) later flips a dangling 'streaming' row to
+    // 'aborted'. The DB is now the single source of truth for the turn — the
+    // socket is never required for the write path. A failed upfront insert is
+    // logged and leaves assistantId undefined; the per-step/terminal updates then
+    // no-op (guarded below) so the turn still streams to the user.
+    let assistantId: string | undefined;
+    try {
+      const seed = flushAssistant([], '', 'streaming');
+      const seeded = await this.aiChatMessageRepo.insert({
+        chatId,
+        workspaceId: workspace.id,
+        userId: user.id,
+        role: 'assistant',
+        content: seed.content,
+        // jsonb columns: cast through never (same as the user insert above).
+        toolCalls: (seed.toolCalls ?? null) as never,
+        metadata: seed.metadata as never,
+        status: seed.status,
+      });
+      assistantId = seeded?.id;
+    } catch (err) {
+      this.logger.error(
+        `Failed to insert upfront assistant row (chat ${chatId}, workspace ${workspace.id})`,
+        err as Error,
+      );
+    }
+
+    // Per-step (non-terminal) update: persist the finished steps the moment a
+    // step ends. Tolerant — a failed update is logged and swallowed so it never
+    // throws into the stream. Keeps status 'streaming'.
+    const updateStreaming = async (): Promise<void> => {
+      if (!assistantId) return;
+      // Cheap short-circuit once the turn is finalized (see `finalized` below).
+      // The AUTHORITATIVE guard is `onlyIfStreaming` on the UPDATE: a late
+      // fire-and-forget step update could still be in flight on another pool
+      // connection when finalize runs, so the SQL `WHERE status='streaming'`
+      // (not this flag) is what prevents it clobbering the terminal row.
+      if (finalized) return;
+      try {
+        await this.aiChatMessageRepo.update(
+          assistantId,
+          workspace.id,
+          flushAssistant(capturedSteps, '', 'streaming'),
+          { onlyIfStreaming: true },
+        );
+      } catch (err) {
+        this.logger.warn(
+          `Failed to update streaming assistant row: ${
+            err instanceof Error ? err.message : 'unknown error'
+          }`,
+        );
+      }
+    };
+
+    // Serialize the per-step updates (#183 review): onStepFinish fires them
+    // without await, so two could otherwise commit out of order on different pool
+    // connections (step N landing after N+1). Chaining each onto the previous
+    // keeps the persisted row monotonic with step order; each link short-circuits
+    // on `finalized`, so a tail of late updates is cheap.
+    let stepUpdateChain: Promise<void> = Promise.resolve();
+
+    // Terminal finalize: write the completed/error/aborted row exactly once
+    // across the (mutually-exclusive, at-most-once) onFinish/onError/onAbort
+    // callbacks — mirroring the pre-#183 persist-at-most-once guard for the
+    // TERMINAL status (the row may be updated many times with 'streaming' before
+    // this fires once).
+    let finalized = false;
+    const finalizeAssistant = async (
+      flushed: AssistantFlush,
+    ): Promise<void> => {
+      if (finalized) return;
+      finalized = true;
+      const plan = planFinalizeAssistant(assistantId);
+      try {
+        // Shared dispatch (see applyFinalize): UPDATE the upfront row, or — when
+        // the upfront insert failed (kind 'insert') — INSERT the terminal row as
+        // the only safety against losing the turn entirely.
+        await applyFinalize(
+          this.aiChatMessageRepo,
+          plan,
+          { chatId, workspaceId: workspace.id, userId: user.id },
+          flushed,
+        );
+      } catch (err) {
+        this.logger.error(
+          `Failed to finalize assistant message (kind=${plan.kind})`,
+          err as Error,
+        );
+      }
+    };
+
     // DIAGNOSTIC (Safari stream-drop investigation) — temporary. Measure
     // first-chunk latency, the model-silent gap right before a disconnect, and
     // how many SSE heartbeats were written, so a Safari drop can be classified
@@ -428,6 +530,12 @@ export class AiChatService {
           // the in-progress accumulator for the next step.
           capturedSteps.push(step as StepLike);
           inProgressText = '';
+          // Step-granular durability (#183): persist this finished step (its text +
+          // tool calls + tool RESULTS) the moment it ends, so a process death after
+          // this point still recovers the step. Not awaited here (never block the
+          // stream), but SERIALIZED via stepUpdateChain so the writes commit in
+          // step order; updateStreaming is error-tolerant (logs + swallows).
+          stepUpdateChain = stepUpdateChain.then(() => updateStreaming());
         },
         onFinish: async ({ text, finishReason, totalUsage, usage, steps }) => {
           // DIAGNOSTIC (Safari stream-drop investigation) — temporary: success
@@ -438,28 +546,31 @@ export class AiChatService {
               `firstChunkLatency=${firstModelChunkAt ? firstModelChunkAt - streamStartedAt : 'none'}ms ` +
               `heartbeatsSent=${heartbeatsSent} steps=${steps.length}`,
           );
-        await persistAssistant({
-          text,
-          toolCalls: serializeSteps(steps),
-          metadata: {
-            finishReason,
-            // Persist the turn's cumulative usage WITH reasoning tokens resolved
-            // from either the new `outputTokenDetails` or the deprecated top-level
-            // field, so reopened history / the Markdown export show the thinking
-            // token cost too.
-            usage: normalizeStreamUsage(totalUsage as StreamUsage) ?? totalUsage,
-            // Final-step usage = the context actually fed to the model on the last LLM
-            // call (full history + tool results) plus the answer it just generated.
-            // input+output of the FINAL step ≈ the conversation's CURRENT context size,
-            // distinct from totalUsage which sums every step (cumulative tokens spent).
+          // Finalize the assistant row (#183): the upfront 'streaming' row is
+          // UPDATEd to 'completed' with the turn's final text, cumulative usage and
+          // full UIMessage parts. We pass the SDK `steps` (which carry the final
+          // step's text) as the captured steps so metadata.parts matches the
+          // pre-#183 onFinish record exactly; `inProgressText` is '' here (the last
+          // step already finished). Final-step usage (usage.input+output) ≈ the
+          // conversation's CURRENT context size, distinct from totalUsage.
+          //
+          // COLUMN-SEMANTICS NOTE (#183): `content` is built by flushAssistant as
+          // the CONCATENATION of every step's text (stepsText), whereas pre-#183
+          // it stored only the FINAL step's text. This is a deliberate, harmless
+          // change: the UI and the Markdown export render from `metadata.parts`
+          // (per-step text + tool parts), not from `content`; `content` is the
+          // plain-text projection (full-text search / fallback). A multi-step
+          // turn's `content` therefore now holds all steps' prose, not just the
+          // last block.
+          await finalizeAssistant(
+            flushAssistant(steps as StepLike[], '', 'completed', {
+              finishReason: finishReason as string,
+              usage: totalUsage as StreamUsage,
               contextTokens:
-              (usage?.inputTokens ?? 0) + (usage?.outputTokens ?? 0) || undefined,
-            // Persist the FULL set of UIMessage parts for the turn (text +
-            // tool-call/result), so the rebuilt history replays prior tool
-            // context to the model on later turns.
-            parts: assistantParts(steps, text),
-          },
-        });
+                (usage?.inputTokens ?? 0) + (usage?.outputTokens ?? 0) ||
+                undefined,
+            }),
+          );
           // Lifecycle: release the external MCP clients leased for this turn.
           await closeExternalClients();
 
@@ -495,16 +606,14 @@ export class AiChatService {
               `firstChunkLatency=${firstModelChunkAt ? firstModelChunkAt - streamStartedAt : 'none'}ms ` +
               `silentGapBeforeDrop=${diagNow - lastModelChunkAt}ms heartbeatsSent=${heartbeatsSent}`,
           );
-        // Persist the PARTIAL answer streamed before the failure (text + any
+          // Finalize the PARTIAL answer streamed before the failure (text + any
           // finished tool steps) WITH the error in metadata, so the turn shows what
-        // the user already saw plus the cause — not just a bare error.
-        await persistAssistant(
-          buildPartialAssistantRecord(
-            capturedSteps,
-            inProgressText,
-            'error',
-            errorText,
-          ),
+          // the user already saw plus the cause — not just a bare error. Status
+          // 'error' (#183).
+          await finalizeAssistant(
+            flushAssistant(capturedSteps, inProgressText, 'error', {
+              error: errorText,
+            }),
           );
           await closeExternalClients();
         },
@@ -528,13 +637,26 @@ export class AiChatService {
               `silentGapBeforeDrop=${diagNow - lastModelChunkAt}ms heartbeatsSent=${heartbeatsSent} ` +
               `steps=${steps.length}`,
           );
-        await persistAssistant(
-          buildPartialAssistantRecord(capturedSteps, inProgressText, 'aborted'),
+          await finalizeAssistant(
+            flushAssistant(capturedSteps, inProgressText, 'aborted'),
           );
           await closeExternalClients();
         },
       });
 
+      // Drain the stream independently of the client socket so the turn always
+      // runs to completion (or to its abort) and the terminal callbacks
+      // (onFinish/onError/onAbort) fire — releasing the per-turn object graph
+      // (history, the per-request toolset closures, captured steps, SDK buffers)
+      // and closing leased MCP clients. WITHOUT this, a client disconnect leaves
+      // the pipe's dead socket as the only reader; backpressure stalls the stream,
+      // the callbacks never run, and every dropped turn stays rooted in memory —
+      // the heap-OOM leak. consumeStream removes that backpressure (AI SDK v6
+      // "Handling client disconnects"). NOT awaited (fire-and-forget); the stream
+      // errors are already logged by the streamText `onError` callback above, so
+      // swallow here to avoid an unhandledRejection.
+      void result.consumeStream({ onError: () => undefined });
+
       // Stream the UI-message protocol straight to the hijacked Node response.
       // Without onError the AI SDK masks the cause ('An error occurred.') and the
       // UI shows a generic failure. Surface the real provider message instead.
@@ -639,7 +761,10 @@ export class AiChatService {
         'punctuation at the end.',
       prompt: firstMessage.slice(0, 2000),
     });
-    const title = text.trim().replace(/^["']|["']$/g, '').slice(0, 120);
+    const title = text
+      .trim()
+      .replace(/^["']|["']$/g, '')
+      .slice(0, 120);
     if (title) {
       await this.aiChatRepo.update(chatId, { title }, workspaceId);
     }
@@ -962,38 +1087,132 @@ export function rowToUiMessage(row: AiChatMessage): Omit<UIMessage, 'id'> & {
 }
 
 /**
- * Build the assistant-message record persisted on a partial/failed turn (the
- * streamText onError / onAbort paths). Captures the partial answer the user
- * already saw: each finished step's text + tool parts (via assistantParts),
- * then the in-progress step's text appended last. When `errorText` is provided
- * it is recorded in metadata.error so the cause shows in history; an aborted
- * turn passes none. Pure, so the partial-recording shape is unit-testable
- * without seaming streamText.
+ * The persisted-row patch shape produced by {@link flushAssistant}. It is the
+ * SAME shape the assistant repo insert/update consume (content + toolCalls +
+ * metadata) plus the lifecycle `status` column added in #183.
  */
-export function buildPartialAssistantRecord(
-  steps: ReadonlyArray<StepLike> | undefined,
+export interface AssistantFlush {
+  content: string;
+  toolCalls: unknown;
+  metadata: Record<string, unknown>;
+  status: 'streaming' | 'completed' | 'error' | 'aborted';
+}
+
+/**
+ * Pure decision for the terminal finalize (#183): given whether the upfront
+ * assistant row exists (`assistantId`), choose whether the terminal payload is
+ * written by UPDATEing that row or — when the upfront insert failed and there is
+ * no id — by INSERTing a fresh terminal row so the turn is not lost entirely.
+ * Returns `{ kind: 'update', id }` or `{ kind: 'insert' }`. Extracted so the
+ * fallback-insert branch (the only safety against losing a turn whose upfront
+ * insert failed) is unit-testable without seaming streamText.
+ */
+export function planFinalizeAssistant(
+  assistantId: string | undefined,
+): { kind: 'update'; id: string } | { kind: 'insert' } {
+  return assistantId ? { kind: 'update', id: assistantId } : { kind: 'insert' };
+}
+
+/** The repo surface the terminal finalize needs (structural — the real repo and
+ *  a test mock both satisfy it). */
+export interface FinalizeRepo {
+  insert(insertable: Record<string, unknown>): Promise<unknown>;
+  update(
+    id: string,
+    workspaceId: string,
+    patch: AssistantFlush,
+  ): Promise<unknown>;
+}
+
+/**
+ * Apply a finalize `plan` to the repo with the terminal `flushed` payload (#183):
+ * UPDATE the upfront row, or INSERT a fresh terminal row as the fallback when the
+ * upfront insert failed. The SINGLE dispatch shared by the service's
+ * finalizeAssistant and its test, so the test exercises the real path instead of
+ * a copy (#186 review). Pure of error handling — the caller wraps it.
+ */
+export async function applyFinalize(
+  repo: FinalizeRepo,
+  plan: { kind: 'update'; id: string } | { kind: 'insert' },
+  base: { chatId: string; workspaceId: string; userId: string },
+  flushed: AssistantFlush,
+): Promise<void> {
+  if (plan.kind === 'update') {
+    await repo.update(plan.id, base.workspaceId, flushed);
+    return;
+  }
+  await repo.insert({
+    chatId: base.chatId,
+    workspaceId: base.workspaceId,
+    userId: base.userId,
+    role: 'assistant',
+    content: flushed.content,
+    toolCalls: flushed.toolCalls ?? null,
+    metadata: flushed.metadata,
+    status: flushed.status,
+  });
+}
+
+/**
+ * PURE assistant-row builder (#183 step-granular durability). Given the turn's
+ * accumulated steps + the in-progress (not-yet-finished) text + the lifecycle
+ * status, it returns the row patch to persist. The SAME path runs for the
+ * upfront insert (empty steps, status 'streaming'), every per-step update, and
+ * the terminal finalize (completed/error/aborted) — and a future background
+ * worker can call it identically, so it must stay a pure function of its inputs
+ * (NO `this`, no IO).
+ *
+ * `metadata.parts` is built by assistantParts over the finished steps, then the
+ * in-progress text appended as a trailing text part, so rowToUiMessage /
+ * findRecent keep replaying the turn unchanged. `metadata.finishReason`,
+ * `metadata.error`, `metadata.usage` and `metadata.contextTokens` are attached
+ * only when provided/relevant, matching the pre-#183 onFinish/onError records.
+ */
+export function flushAssistant(
+  capturedSteps: ReadonlyArray<StepLike> | undefined,
   inProgressText: string,
-  finishReason: 'error' | 'aborted',
-  errorText?: string,
-): { text: string; toolCalls: unknown; metadata: Record<string, unknown> } {
-  const finished = steps ?? [];
+  status: 'streaming' | 'completed' | 'error' | 'aborted',
+  extra?: {
+    finishReason?: string;
+    usage?: ChatStreamUsage | StreamUsage | undefined;
+    contextTokens?: number;
+    error?: string;
+  },
+): AssistantFlush {
+  const finished = capturedSteps ?? [];
   const stepsText = finished.map((s) => s.text ?? '').join('');
   const trailing = inProgressText ?? '';
   // assistantParts emits text parts only for FINISHED steps; append the
-  // in-progress step's text (the answer cut off by the error) as the last text
-  // part so the persisted parts match what streamed to the client.
+  // in-progress step's text (the partial answer cut off by an error/abort, or
+  // simply not yet flushed mid-stream) as the last text part so the persisted
+  // parts match what streamed to the client.
   const parts = assistantParts(finished, '') as unknown as Array<
     Record<string, unknown>
   >;
   if (trailing) parts.push({ type: 'text', text: trailing });
-  return {
-    text: stepsText + trailing,
-    toolCalls: serializeSteps(finished),
-    metadata: {
-      finishReason,
+
+  const metadata: Record<string, unknown> = {
     parts: parts as unknown as UIMessage['parts'],
-      ...(errorText ? { error: errorText } : {}),
-    },
+  };
+  // finishReason: prefer an explicit one; else derive a sensible value from the
+  // terminal status (so onError/onAbort records keep their historical reason).
+  if (extra?.finishReason) {
+    metadata.finishReason = extra.finishReason;
+  } else if (status === 'error' || status === 'aborted') {
+    metadata.finishReason = status;
+  }
+  if (extra?.usage !== undefined) {
+    metadata.usage =
+      normalizeStreamUsage(extra.usage as StreamUsage) ?? extra.usage;
+  }
+  if (extra?.contextTokens) metadata.contextTokens = extra.contextTokens;
+  if (extra?.error) metadata.error = extra.error;
+
+  return {
+    content: stepsText + trailing,
+    toolCalls: serializeSteps(finished),
+    metadata,
+    status,
   };
 }
 

apps/server/src/core/ai-chat/chat-markdown.util.spec.ts

@@ -0,0 +1,295 @@
+import { buildChatMarkdown, normalizeLang } from './chat-markdown.util';
+import type { AiChatMessage } from '@docmost/db/types/entity.types';
+
+/**
+ * normalizeLang: the client sends `i18n.language` — a FULL locale tag like
+ * 'en-US' / 'ru-RU', NOT a bare 'en'/'ru'. A `@IsIn(['en','ru'])` DTO rejected
+ * that with a 400 (caught in real-browser testing); the export now accepts any
+ * string and normalizes here. Guards that regression.
+ */
+describe('normalizeLang', () => {
+  it("maps any 'ru…' locale tag to ru", () => {
+    expect(normalizeLang('ru')).toBe('ru');
+    expect(normalizeLang('ru-RU')).toBe('ru');
+    expect(normalizeLang('RU-ru')).toBe('ru');
+  });
+
+  it('maps everything else (incl. region-qualified English) to en', () => {
+    expect(normalizeLang('en')).toBe('en');
+    expect(normalizeLang('en-US')).toBe('en');
+    expect(normalizeLang('fr-FR')).toBe('en');
+    expect(normalizeLang(undefined)).toBe('en');
+    expect(normalizeLang('')).toBe('en');
+  });
+});
+
+/**
+ * Unit tests for the SERVER Markdown export (#183). Mirrors the coverage of the
+ * (now-removed) client chat-markdown tests: heading/metadata, role labels, text
+ * + tool blocks, token footers, the interrupted-turn note, and NULL-status
+ * (legacy) rows. The export embeds a live `new Date().toISOString()` timestamp;
+ * we never assert it, only the deterministic structure.
+ */
+
+function row(partial: Partial<AiChatMessage>): AiChatMessage {
+  return {
+    id: partial.id ?? 'id',
+    chatId: partial.chatId ?? 'chat-1',
+    workspaceId: partial.workspaceId ?? 'ws-1',
+    userId: partial.userId ?? null,
+    role: partial.role ?? 'user',
+    content: partial.content ?? null,
+    toolCalls: partial.toolCalls ?? null,
+    metadata: partial.metadata ?? null,
+    status: partial.status ?? null,
+    createdAt: partial.createdAt ?? ('2026-06-21T00:00:00.000Z' as never),
+    updatedAt: partial.updatedAt ?? ('2026-06-21T00:00:00.000Z' as never),
+    deletedAt: partial.deletedAt ?? null,
+  } as AiChatMessage;
+}
+
+describe('buildChatMarkdown (server) — structure', () => {
+  it('emits the title heading, chat id and message count', () => {
+    const md = buildChatMarkdown({
+      title: 'My chat',
+      chatId: 'chat-123',
+      rows: [],
+    });
+    expect(md).toContain('# My chat');
+    expect(md).toContain('- Chat ID: `chat-123`');
+    expect(md).toContain('- Messages: 0');
+  });
+
+  it('falls back to "Untitled chat" with no title (en)', () => {
+    const md = buildChatMarkdown({ title: null, chatId: 'c', rows: [] });
+    expect(md).toContain('# Untitled chat');
+  });
+
+  it('localizes fixed labels with lang=ru (structure stays English)', () => {
+    const md = buildChatMarkdown({
+      title: null,
+      chatId: 'c',
+      lang: 'ru',
+      rows: [row({ role: 'assistant', content: 'hi' })],
+    });
+    expect(md).toContain('# Без названия');
+    expect(md).toContain('## 1. ИИ-агент');
+    // Structural words remain English.
+    expect(md).toContain('- Chat ID:');
+  });
+
+  it('numbers messages and labels roles (You / AI agent)', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({ role: 'user', content: 'question' }),
+        row({ role: 'assistant', content: 'answer' }),
+      ],
+    });
+    expect(md).toContain('## 1. You');
+    expect(md).toContain('question');
+    expect(md).toContain('## 2. AI agent');
+    expect(md).toContain('answer');
+  });
+
+  it('renders a tool part with fenced input/output and the friendly label', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'done',
+          metadata: {
+            parts: [
+              {
+                type: 'tool-getPage',
+                state: 'output-available',
+                input: { id: 'p1' },
+                output: { title: 'Hello' },
+              },
+              { type: 'text', text: 'done' },
+            ],
+          } as never,
+        }),
+      ],
+    });
+    expect(md).toContain('**Tool: Read page** (`getPage`) — done');
+    expect(md).toContain('Input:');
+    expect(md).toContain('"id": "p1"');
+    expect(md).toContain('Output:');
+    expect(md).toContain('"title": "Hello"');
+  });
+
+  // #186 re-review pt 1: restore the parity coverage of the removed client spec —
+  // error state, unknown-tool fallback (en + ru), and the circular-stringify catch.
+  it('renders a tool part in the error state with its errorText', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          metadata: {
+            parts: [
+              {
+                type: 'tool-getPage',
+                state: 'output-error',
+                input: { id: 'p1' },
+                errorText: 'page not found',
+              },
+            ],
+          } as never,
+        }),
+      ],
+    });
+    expect(md).toContain('**Tool: Read page** (`getPage`) — error');
+    expect(md).toContain('**Error:** page not found');
+  });
+
+  it('falls back to "Ran tool <name>" for an unknown tool (en) and the ru variant', () => {
+    const parts = [
+      {
+        type: 'tool-mysteryTool',
+        state: 'output-available',
+        output: { ok: 1 },
+      },
+    ];
+    const en = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [row({ role: 'assistant', metadata: { parts } as never })],
+    });
+    expect(en).toContain('**Tool: Ran tool mysteryTool** (`mysteryTool`)');
+    const ru = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      lang: 'ru',
+      rows: [row({ role: 'assistant', metadata: { parts } as never })],
+    });
+    expect(ru).toContain('Выполнил инструмент mysteryTool');
+  });
+
+  it('does not throw on a circular tool output (falls back to String)', () => {
+    const circular: Record<string, unknown> = {};
+    circular.self = circular;
+    expect(() =>
+      buildChatMarkdown({
+        title: 'T',
+        chatId: 'c',
+        rows: [
+          row({
+            role: 'assistant',
+            metadata: {
+              parts: [
+                {
+                  type: 'tool-getPage',
+                  state: 'output-available',
+                  output: circular,
+                },
+              ],
+            } as never,
+          }),
+        ],
+      }),
+    ).not.toThrow();
+  });
+
+  it('emits a token footer + total when usage is present', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'a',
+          metadata: {
+            usage: {
+              inputTokens: 100,
+              outputTokens: 20,
+              totalTokens: 120,
+              reasoningTokens: 8,
+            },
+          } as never,
+        }),
+      ],
+    });
+    expect(md).toContain('- Total tokens: 120');
+    expect(md).toContain(
+      '_Tokens — in: 100, out: 20, reasoning: 8, total: 120_',
+    );
+  });
+
+  it('flags a still-streaming (interrupted) row', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({ role: 'assistant', content: 'partial', status: 'streaming' }),
+      ],
+    });
+    expect(md).toContain('still being generated');
+  });
+
+  it('does NOT flag a completed row', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [row({ role: 'assistant', content: 'final', status: 'completed' })],
+    });
+    expect(md).not.toContain('still being generated');
+  });
+
+  it('renders a legacy NULL-status row (no parts) from plain content', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({ role: 'assistant', content: 'legacy answer', status: null }),
+      ],
+    });
+    expect(md).toContain('legacy answer');
+    expect(md).not.toContain('still being generated');
+  });
+
+  it('renders a persisted error', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: '',
+          status: 'error',
+          metadata: { error: '401: Unauthorized' } as never,
+        }),
+      ],
+    });
+    expect(md).toContain('**⚠️ Error:** 401: Unauthorized');
+  });
+
+  it('escapes embedded triple-backtick fences with a longer delimiter', () => {
+    const md = buildChatMarkdown({
+      title: 'T',
+      chatId: 'c',
+      rows: [
+        row({
+          role: 'assistant',
+          content: 'x',
+          metadata: {
+            parts: [
+              {
+                type: 'tool-getPage',
+                state: 'output-available',
+                output: '```inner```',
+              },
+            ],
+          } as never,
+        }),
+      ],
+    });
+    // A 4-backtick fence wraps content that itself contains a 3-backtick run.
+    expect(md).toContain('````');
+  });
+});

apps/server/src/core/ai-chat/chat-markdown.util.ts

@@ -0,0 +1,299 @@
+/**
+ * Server-side Markdown export for an AI agent chat (#183). The DB is the single
+ * source of truth: this renders a chat purely from its persisted message rows
+ * (`AiChatMessage[]` — role / content / metadata.parts / toolCalls / usage).
+ * Because the assistant row is now persisted UPFRONT and updated per step, an
+ * interrupted turn is included up to its last finished step.
+ *
+ * Ported from the client `utils/chat-markdown.ts`. It is a PURE function (apart
+ * from `new Date()` for the export timestamp), so it is straightforward to
+ * unit-test and a future background worker can reuse it.
+ *
+ * Only a few fixed role/tool labels are localized via the `lang` param; the
+ * structural document words (Input/Output/Error/Tokens/...) stay English because
+ * the output is a technical artifact.
+ */
+
+import type { AiChatMessage } from '@docmost/db/types/entity.types';
+
+/** Supported export label languages. Defaults to English. */
+export type ExportLang = 'en' | 'ru';
+
+/**
+ * Normalize an arbitrary client locale code to a supported export language. The
+ * client sends `i18n.language`, which is a FULL locale tag (e.g. `en-US`,
+ * `ru-RU`), not a bare `en`/`ru` — so match on the language subtag and fall back
+ * to English for anything non-Russian.
+ */
+export function normalizeLang(lang?: string): ExportLang {
+  return lang?.toLowerCase().startsWith('ru') ? 'ru' : 'en';
+}
+
+/** A single AI SDK UIMessage part (text part or a tool part). */
+interface ExportPart {
+  type: string;
+  text?: string;
+  state?: string;
+  toolName?: string;
+  input?: unknown;
+  output?: unknown;
+  errorText?: string;
+}
+
+/** Authoritative per-turn usage the server attaches to a message row. */
+interface UsageLike {
+  inputTokens?: number;
+  outputTokens?: number;
+  totalTokens?: number;
+  reasoningTokens?: number;
+}
+
+/** Localized label table. The client-side Markdown builder was removed by #183
+ *  (the export is now server-side only), so this no longer mirrors a second
+ *  exporter — instead the tool-action labels are kept in parity with the
+ *  on-screen action-log labels in the client's `tool-parts.tsx` (`toolLabelKey`)
+ *  so the export reads the same as the UI. Only role + tool-action labels are
+ *  localized; everything structural is an English constant in the renderer. */
+const LABELS: Record<
+  ExportLang,
+  {
+    untitled: string;
+    aiAgent: string;
+    you: string;
+    tools: Record<string, string>;
+    ranTool: (name: string) => string;
+    stillGenerating: string;
+  }
+> = {
+  en: {
+    untitled: 'Untitled chat',
+    aiAgent: 'AI agent',
+    you: 'You',
+    tools: {
+      searchPages: 'Searched pages',
+      getPage: 'Read page',
+      createPage: 'Created page',
+      updatePageContent: 'Updated page',
+      renamePage: 'Renamed page',
+      movePage: 'Moved page',
+      deletePage: 'Deleted page (to trash)',
+      createComment: 'Commented',
+      resolveComment: 'Resolved comment',
+    },
+    ranTool: (name) => `Ran tool ${name}`,
+    stillGenerating:
+      'This message is still being generated — the export captured a partial, in-progress response.',
+  },
+  ru: {
+    untitled: 'Без названия',
+    aiAgent: 'ИИ-агент',
+    you: 'Вы',
+    tools: {
+      searchPages: 'Искал по страницам',
+      getPage: 'Прочитал страницу',
+      createPage: 'Создал страницу',
+      updatePageContent: 'Обновил страницу',
+      renamePage: 'Переименовал страницу',
+      movePage: 'Переместил страницу',
+      deletePage: 'Удалил страницу (в корзину)',
+      createComment: 'Прокомментировал',
+      resolveComment: 'Закрыл комментарий',
+    },
+    ranTool: (name) => `Выполнил инструмент ${name}`,
+    stillGenerating:
+      'Это сообщение всё ещё генерируется — экспорт захватил частичный, незавершённый ответ.',
+  },
+};
+
+/** True for AI SDK tool parts (static `tool-*` or `dynamic-tool`). */
+function isToolPart(type: string): boolean {
+  return type.startsWith('tool-') || type === 'dynamic-tool';
+}
+
+/** Extract the tool name from a part `type` of `tool-${name}` (or dynamic). */
+function getToolName(part: ExportPart): string {
+  if (part.type === 'dynamic-tool') return part.toolName ?? '';
+  return part.type.startsWith('tool-')
+    ? part.type.slice('tool-'.length)
+    : part.type;
+}
+
+/** Map an AI SDK tool-part state to the 3 states the action-log renders. */
+function toolRunState(state: string | undefined): 'running' | 'done' | 'error' {
+  if (state === 'output-error' || state === 'output-denied') return 'error';
+  if (state === 'output-available') return 'done';
+  return 'running';
+}
+
+/** Resolve a tool's friendly action-log label (localized) from its name. */
+function toolLabel(name: string, lang: ExportLang): string {
+  return LABELS[lang].tools[name] ?? LABELS[lang].ranTool(name);
+}
+
+/**
+ * Stringify an arbitrary tool input/output value for a fenced block. Strings
+ * pass through as-is; everything else is pretty-printed JSON, falling back to
+ * `String(value)` if serialization throws (e.g. a circular structure).
+ */
+function stringify(value: unknown): string {
+  if (typeof value === 'string') return value;
+  try {
+    return JSON.stringify(value, null, 2);
+  } catch {
+    return String(value);
+  }
+}
+
+/**
+ * Wrap `code` in a fenced code block whose backtick delimiter is LONGER than the
+ * longest backtick run inside the content, so embedded backticks (or a literal
+ * ``` fence) never break out of the block. Minimum 3 backticks.
+ */
+function fence(code: string, lang = ''): string {
+  const runs: string[] = code.match(/`+/g) ?? [];
+  const longest = runs.reduce((m, s) => Math.max(m, s.length), 0);
+  const delim = '`'.repeat(Math.max(3, longest + 1));
+  return `${delim}${lang}\n${code}\n${delim}`;
+}
+
+/** Per-row token count, mirroring the header sum in the client window. */
+function rowTokens(usage: UsageLike): number {
+  return (
+    usage.totalTokens ?? (usage.inputTokens ?? 0) + (usage.outputTokens ?? 0)
+  );
+}
+
+/** Render one message's UIMessage parts into an array of Markdown blocks
+ *  (text blocks + tool blocks). Mirrors the client renderer / MessageItem. */
+function renderMessageParts(parts: ExportPart[], lang: ExportLang): string[] {
+  const out: string[] = [];
+
+  for (const part of parts) {
+    if (part.type === 'text') {
+      const text = (part.text ?? '').trim();
+      if (text.length > 0) out.push(text);
+      continue;
+    }
+
+    if (!isToolPart(part.type)) continue;
+
+    const name = getToolName(part);
+    const label = toolLabel(name, lang);
+    const state = toolRunState(part.state);
+
+    const toolLines: string[] = [`**Tool: ${label}** (\`${name}\`) — ${state}`];
+    if (part.input !== undefined) {
+      toolLines.push('Input:');
+      toolLines.push(fence(stringify(part.input), 'json'));
+    }
+    if (part.output !== undefined) {
+      toolLines.push('Output:');
+      toolLines.push(fence(stringify(part.output), 'json'));
+    }
+    if (part.errorText) {
+      toolLines.push(`**Error:** ${part.errorText}`);
+    }
+    out.push(toolLines.join('\n\n'));
+  }
+
+  return out;
+}
+
+/** Resolve a persisted row's parts: prefer the rich persisted parts, else a
+ *  single text part built from the plain-text content (mirrors rowToUiMessage). */
+function rowParts(row: AiChatMessage): ExportPart[] {
+  const meta = (row.metadata ?? {}) as { parts?: ExportPart[] };
+  return Array.isArray(meta.parts) && meta.parts.length > 0
+    ? meta.parts
+    : [{ type: 'text', text: row.content ?? '' }];
+}
+
+/**
+ * Serialize a chat to a Markdown string from its persisted rows. Source = DB
+ * ONLY (no live client state). A row whose `status` is still 'streaming' is an
+ * interrupted turn that the export captured mid-flight; it is rendered up to its
+ * last finished step and flagged "still generating".
+ */
+export function buildChatMarkdown(args: {
+  title: string | null;
+  chatId: string;
+  rows: AiChatMessage[];
+  // Accepts a full client locale tag (e.g. 'en-US'/'ru-RU'); normalized below.
+  lang?: string;
+}): string {
+  const { title, chatId, rows } = args;
+  const lang: ExportLang = normalizeLang(args.lang);
+  const L = LABELS[lang];
+  const blocks: string[] = [];
+
+  const heading = (title ?? '').trim() || L.untitled;
+  blocks.push(`# ${heading}`);
+
+  const usageOf = (row: AiChatMessage): UsageLike | undefined => {
+    const meta = (row.metadata ?? {}) as { usage?: UsageLike };
+    return meta.usage;
+  };
+  const errorOf = (row: AiChatMessage): string | undefined => {
+    const meta = (row.metadata ?? {}) as { error?: string };
+    return meta.error;
+  };
+
+  // Metadata bullet list. Total tokens is only shown when there is a sum.
+  const totalTokens = rows.reduce((sum, row) => {
+    const usage = usageOf(row);
+    return usage ? sum + rowTokens(usage) : sum;
+  }, 0);
+  const meta = [
+    `- Chat ID: \`${chatId}\``,
+    `- Exported: ${new Date().toISOString()}`,
+    `- Messages: ${rows.length}`,
+  ];
+  if (totalTokens > 0) meta.push(`- Total tokens: ${totalTokens}`);
+  blocks.push(meta.join('\n'));
+
+  rows.forEach((row, index) => {
+    blocks.push('---');
+
+    const roleLabel = row.role === 'assistant' ? L.aiAgent : L.you;
+    blocks.push(`## ${index + 1}. ${roleLabel}`);
+
+    // Created-at kept in source as an HTML comment (out of the rendered prose).
+    if (row.createdAt) {
+      const iso =
+        row.createdAt instanceof Date
+          ? row.createdAt.toISOString()
+          : String(row.createdAt);
+      blocks.push(`<!-- ${iso} -->`);
+    }
+
+    blocks.push(...renderMessageParts(rowParts(row), lang));
+
+    // A still-'streaming' row is an interrupted/in-progress turn captured by the
+    // export; record that so the partial answer is not mistaken for complete.
+    if (row.status === 'streaming') {
+      blocks.push(`_⏳ ${L.stillGenerating}_`);
+    }
+
+    const error = errorOf(row);
+    if (error) {
+      blocks.push(`**⚠️ Error:** ${error}`);
+    }
+
+    const usage = usageOf(row);
+    if (usage) {
+      const total = usage.totalTokens ?? rowTokens(usage);
+      const reasoning =
+        usage.reasoningTokens && usage.reasoningTokens > 0
+          ? `, reasoning: ${usage.reasoningTokens}`
+          : '';
+      blocks.push(
+        `_Tokens — in: ${usage.inputTokens ?? '?'}, out: ${
+          usage.outputTokens ?? '?'
+        }${reasoning}, total: ${total}_`,
+      );
+    }
+  });
+
+  // Blank line between blocks so the Markdown renders cleanly.
+  return blocks.join('\n\n');
+}

apps/server/src/core/ai-chat/dto/ai-chat.dto.ts

@@ -26,3 +26,17 @@ export class GetChatMessagesDto {
   @IsString()
   cursor?: string;
 }
+
+/** Export a chat to Markdown (#183). `lang` localizes the few fixed
+ *  role/tool-action labels; defaults to English server-side. */
+export class ExportChatDto {
+  @IsString()
+  chatId: string;
+
+  // A full client locale tag (e.g. 'en-US', 'ru-RU') — normalized server-side to
+  // a supported export language (see normalizeLang). Accept any string so a
+  // region-qualified locale is not rejected (the 400 that broke the real client).
+  @IsOptional()
+  @IsString()
+  lang?: string;
+}

apps/server/src/core/ai-chat/external-mcp/mcp-call-timeout.spec.ts

@@ -0,0 +1,205 @@
+import { type Tool, type ToolCallOptions } from 'ai';
+import {
+  wrapToolWithCallTimeout,
+  wrapToolsWithCallTimeout,
+} from './mcp-clients.service';
+import {
+  mcpStreamTimeoutMs,
+  mcpCallTimeoutMs,
+} from '../../../integrations/ai/ai-streaming-fetch';
+
+/**
+ * Per-call total-timeout guard for external MCP tools (mcp-clients.service).
+ *
+ * `@ai-sdk/mcp`'s tool execute has NO built-in per-call timeout — a tool that
+ * keeps the connection warm but never returns is otherwise unbounded. The
+ * wrapper attaches a fresh AbortController + timer per CALL and composes it with
+ * the turn's abortSignal via AbortSignal.any, so EITHER the per-call timeout OR a
+ * client disconnect aborts the in-flight call.
+ *
+ * Fake timers prove the timeout fires WITHOUT real waiting; no leaked timer keeps
+ * the process alive after a fast resolve.
+ */
+const CALL_TIMEOUT_MS = 900_000;
+
+/** Build a Tool around an `execute` impl, mirroring the SDK's minimal shape. */
+function toolWith(
+  execute: (args: unknown, options: ToolCallOptions) => unknown,
+): Tool {
+  return { description: 'x', inputSchema: undefined, execute } as unknown as Tool;
+}
+
+/** Invoke a (possibly wrapped) tool's execute with an optional turn signal. */
+function callExecute(
+  tool: Tool,
+  args: unknown,
+  abortSignal?: AbortSignal,
+): unknown {
+  const execute = tool.execute as (
+    args: unknown,
+    options: ToolCallOptions,
+  ) => unknown;
+  return execute(args, { abortSignal } as ToolCallOptions);
+}
+
+describe('wrapToolWithCallTimeout', () => {
+  beforeEach(() => jest.useFakeTimers());
+  afterEach(() => {
+    jest.clearAllTimers();
+    jest.useRealTimers();
+  });
+
+  it('aborts a tool that only rejects when its abortSignal fires, after ms elapses', async () => {
+    // The tool resolves NEVER on its own — it only settles when the abortSignal
+    // it is handed aborts. So a resolution proves the per-call timer fired and
+    // aborted the call (not the tool finishing by itself).
+    let received: AbortSignal | undefined;
+    const tool = toolWith((_args, options) => {
+      received = options.abortSignal;
+      return new Promise((_resolve, reject) => {
+        options.abortSignal?.addEventListener('abort', () => {
+          reject(options.abortSignal?.reason ?? new Error('aborted'));
+        });
+      });
+    });
+
+    const wrapped = wrapToolWithCallTimeout(tool, CALL_TIMEOUT_MS);
+    const promise = callExecute(wrapped, { q: 'x' }) as Promise<unknown>;
+    // Attach the rejection handler synchronously so advancing timers cannot mark
+    // it an unhandled rejection.
+    const settled = promise.then(
+      () => ({ ok: true as const }),
+      (err: unknown) => ({ ok: false as const, err }),
+    );
+
+    // Nothing fired yet.
+    jest.advanceTimersByTime(CALL_TIMEOUT_MS - 1);
+    // Past the cap -> the per-call timer aborts the composed signal.
+    jest.advanceTimersByTime(2);
+
+    const result = await settled;
+    expect(result.ok).toBe(false);
+    expect(received).toBeInstanceOf(AbortSignal);
+    // The abort reason / rejection mentions the timeout.
+    const message =
+      (result as { err: unknown }).err instanceof Error
+        ? ((result as { err: Error }).err.message)
+        : String((result as { err: unknown }).err);
+    expect(message).toMatch(/timed out after 900000ms/);
+  });
+
+  it('aborts a REAL-client-style tool that never settles and ignores abort (race fix)', async () => {
+    // Models the ACTUAL @ai-sdk/mcp semantics: its in-flight promise does NOT
+    // reject on abort (it only checks the signal when a response arrives), so a
+    // warm-but-stuck call NEVER settles on its own and does NOT listen to the
+    // abort signal. The wrapper must still reject after `ms` via the race — an
+    // implementation that merely `await original(...)` would hang here forever.
+    // This test FAILS against the old await-only code and PASSES with the race.
+    const tool = toolWith(() => new Promise(() => {})); // never settles, no abort
+    const wrapped = wrapToolWithCallTimeout(tool, CALL_TIMEOUT_MS);
+    const promise = callExecute(wrapped, { q: 'x' }) as Promise<unknown>;
+    // Assert the rejection without hanging: drive fake time async so the timer's
+    // abort -> race rejection microtasks flush, then await the rejection.
+    const expectation = expect(promise).rejects.toThrow(/timed out after 900000ms/);
+    await jest.advanceTimersByTimeAsync(CALL_TIMEOUT_MS + 1);
+    await expectation;
+  });
+
+  it('passes a fast tool through and leaks no timer (advancing later does not throw)', async () => {
+    const tool = toolWith(() => Promise.resolve('fast-result'));
+    const wrapped = wrapToolWithCallTimeout(tool, CALL_TIMEOUT_MS);
+
+    const value = await (callExecute(wrapped, {}) as Promise<unknown>);
+    expect(value).toBe('fast-result');
+
+    // The timer was cleared in the finally — advancing past the cap aborts
+    // nothing and throws nothing.
+    expect(() => jest.advanceTimersByTime(CALL_TIMEOUT_MS * 2)).not.toThrow();
+  });
+
+  it('aborts when the caller turn signal aborts before the timeout (disconnect path)', async () => {
+    // Real-client semantics: the tool never settles and does NOT listen to abort,
+    // so the wrapper must reject via the race when the caller's turn signal (a
+    // client disconnect) aborts BEFORE the per-call cap. The race propagates the
+    // caller's abort reason.
+    const tool = toolWith(() => new Promise(() => {})); // never settles, no abort
+    const wrapped = wrapToolWithCallTimeout(tool, CALL_TIMEOUT_MS);
+    const turn = new AbortController();
+    const promise = callExecute(wrapped, {}, turn.signal) as Promise<unknown>;
+    const settled = promise.then(
+      () => ({ ok: true as const }),
+      (err: unknown) => ({ ok: false as const, err }),
+    );
+
+    // Disconnect well before the cap; the per-call timer never fires here.
+    turn.abort(new Error('client disconnected'));
+    const result = await settled;
+    expect(result.ok).toBe(false);
+    const message =
+      (result as { err: unknown }).err instanceof Error
+        ? (result as { err: Error }).err.message
+        : String((result as { err: unknown }).err);
+    // The caller's abort reason propagates through the race.
+    expect(message).toMatch(/client disconnected/);
+  });
+
+  it('passes a tool with no execute through unchanged', () => {
+    const noExecute = { description: 'x', inputSchema: undefined } as unknown as Tool;
+    const wrapped = wrapToolWithCallTimeout(noExecute, CALL_TIMEOUT_MS);
+    // Same object back, execute still absent.
+    expect(wrapped).toBe(noExecute);
+    expect((wrapped as { execute?: unknown }).execute).toBeUndefined();
+  });
+});
+
+describe('wrapToolsWithCallTimeout', () => {
+  beforeEach(() => jest.useFakeTimers());
+  afterEach(() => {
+    jest.clearAllTimers();
+    jest.useRealTimers();
+  });
+
+  it('wraps every tool in the map (each call gets its own guard)', async () => {
+    const tools: Record<string, Tool> = {
+      a: toolWith(() => Promise.resolve('A')),
+      b: toolWith(() => Promise.resolve('B')),
+    };
+    const out = wrapToolsWithCallTimeout(tools, CALL_TIMEOUT_MS);
+    expect(Object.keys(out)).toEqual(['a', 'b']);
+    expect(await (callExecute(out.a, {}) as Promise<unknown>)).toBe('A');
+    expect(await (callExecute(out.b, {}) as Promise<unknown>)).toBe('B');
+  });
+});
+
+describe('mcp timeout env helpers', () => {
+  const ORIG_SILENCE = process.env.AI_MCP_STREAM_TIMEOUT_MS;
+  const ORIG_CALL = process.env.AI_MCP_CALL_TIMEOUT_MS;
+  afterEach(() => {
+    if (ORIG_SILENCE === undefined) delete process.env.AI_MCP_STREAM_TIMEOUT_MS;
+    else process.env.AI_MCP_STREAM_TIMEOUT_MS = ORIG_SILENCE;
+    if (ORIG_CALL === undefined) delete process.env.AI_MCP_CALL_TIMEOUT_MS;
+    else process.env.AI_MCP_CALL_TIMEOUT_MS = ORIG_CALL;
+  });
+
+  it('mcpStreamTimeoutMs defaults to 5 min and honors a positive override', () => {
+    delete process.env.AI_MCP_STREAM_TIMEOUT_MS;
+    expect(mcpStreamTimeoutMs()).toBe(300_000);
+    process.env.AI_MCP_STREAM_TIMEOUT_MS = '60000';
+    expect(mcpStreamTimeoutMs()).toBe(60_000);
+    for (const bad of ['0', '-1', 'x', '']) {
+      process.env.AI_MCP_STREAM_TIMEOUT_MS = bad;
+      expect(mcpStreamTimeoutMs()).toBe(300_000);
+    }
+  });
+
+  it('mcpCallTimeoutMs defaults to 15 min and honors a positive override', () => {
+    delete process.env.AI_MCP_CALL_TIMEOUT_MS;
+    expect(mcpCallTimeoutMs()).toBe(900_000);
+    process.env.AI_MCP_CALL_TIMEOUT_MS = '120000';
+    expect(mcpCallTimeoutMs()).toBe(120_000);
+    for (const bad of ['0', '-1', 'x', '']) {
+      process.env.AI_MCP_CALL_TIMEOUT_MS = bad;
+      expect(mcpCallTimeoutMs()).toBe(900_000);
+    }
+  });
+});

apps/server/src/core/ai-chat/external-mcp/mcp-clients.service.ts

@@ -1,12 +1,16 @@
 import { isIP } from 'node:net';
 import { lookup as dnsLookup, type LookupAddress } from 'node:dns';
 import { Injectable, Logger } from '@nestjs/common';
-import { type Tool } from 'ai';
+import { type Tool, type ToolCallOptions } from 'ai';
 import { createMCPClient } from '@ai-sdk/mcp';
 import { Agent, type Dispatcher } from 'undici';
 import { AiMcpServerRepo } from '@docmost/db/repos/ai-chat/ai-mcp-server.repo';
 import { AiMcpServer } from '@docmost/db/types/entity.types';
-import { streamingDispatcherOptions } from '../../../integrations/ai/ai-streaming-fetch';
+import {
+  streamingDispatcherOptions,
+  mcpStreamTimeoutMs,
+  mcpCallTimeoutMs,
+} from '../../../integrations/ai/ai-streaming-fetch';
 import { SecretBoxService } from '../../../integrations/crypto/secret-box';
 import { isUrlAllowed, isIpAllowed } from './ssrf-guard';
 
@@ -219,6 +223,8 @@ export class McpClientsService {
     const tools: Record<string, Tool> = {};
     const clients: McpClient[] = [];
     const outcomes: ServerOutcome[] = [];
+    // Per-call total wall-clock cap, read once for this build (env-overridable).
+    const callTimeoutMs = mcpCallTimeoutMs();
 
     for (const server of servers) {
       try {
@@ -230,10 +236,13 @@ export class McpClientsService {
           Array.isArray(allow) && allow.length > 0
             ? pick(raw, allow)
             : raw;
+        // Bound each tool's execute with a per-call total-timeout guard before
+        // merging, so a single chatty-but-stuck call is aborted after the cap.
+        const guarded = wrapToolsWithCallTimeout(picked, callTimeoutMs);
         // Namespace each tool with the sanitized server name AND disambiguate
         // against names already merged from earlier servers, so no external
         // tool is silently overwritten on collision.
-        this.mergeNamespaced(tools, picked, server.name, server.id);
+        this.mergeNamespaced(tools, guarded, server.name, server.id);
         outcomes.push({ name: server.name, ok: true });
       } catch (err) {
         // A failed server is skipped — the turn proceeds with the rest. Log a
@@ -400,17 +409,21 @@ export function validateResolvedAddresses(
  * to an IP literal).
  */
 function buildPinnedDispatcher(): Agent {
+  // External-MCP traffic uses a DEDICATED, shorter silence timeout
+  // (`AI_MCP_STREAM_TIMEOUT_MS`, default 5 min) — deliberately tighter than the
+  // chat provider's 15-min `streamTimeoutMs()` — so a byte-silent/hung MCP
+  // upstream is broken in ~5 min instead of 15. We keep the keep-alive options
+  // from `streamingDispatcherOptions()` but OVERRIDE headers/body timeouts.
+  // Accepted trade-off: a legitimately long but byte-silent single tool call,
+  // and an SSE transport idling >5 min BETWEEN tool calls, are also cut here; the
+  // per-call total cap (wrapToolsWithCallTimeout, `AI_MCP_CALL_TIMEOUT_MS`) is the
+  // complementary guard for chatty-but-stuck calls that keep the socket warm yet
+  // never return.
+  const mcpSilenceMs = mcpStreamTimeoutMs();
   return new Agent({
-    // Raise undici's default 300s headers/body timeouts on external MCP traffic
-    // to the same generous-but-finite silence timeout the chat fetch uses (#175).
-    // A long agent turn keeps an SSE transport (e.g. crawl4ai's /mcp/sse) open
-    // across the whole turn; that connection can idle BETWEEN tool calls longer
-    // than 5 min, and undici's bodyTimeout would otherwise sever it mid-task — a
-    // tool-call failure that aborts the streamed turn and shows the user "Lost
-    // connection to the AI provider". A slow single tool call (a crawl) can
-    // likewise exceed headersTimeout. The timeout stays FINITE so a genuinely
-    // hung server is still broken eventually.
     ...streamingDispatcherOptions(),
+    headersTimeout: mcpSilenceMs,
+    bodyTimeout: mcpSilenceMs,
     connect: {
       lookup: (hostname, _options, callback) => {
         // Always resolve ALL addresses ourselves; do not trust the caller's
@@ -572,6 +585,78 @@ function disambiguate(
   return capName(`${name.slice(0, MAX_TOOL_NAME_LENGTH - 14)}_${Date.now()}`);
 }
 
+/**
+ * Wrap every tool's execute with a per-call total-timeout guard so a single
+ * external MCP tool call that keeps the connection warm but never returns is
+ * aborted after `ms` wall-clock (complements the transport silence timeout).
+ */
+export function wrapToolsWithCallTimeout(
+  tools: Record<string, Tool>,
+  ms: number,
+): Record<string, Tool> {
+  const out: Record<string, Tool> = {};
+  for (const [name, t] of Object.entries(tools)) {
+    out[name] = wrapToolWithCallTimeout(t, ms);
+  }
+  return out;
+}
+
+/**
+ * Per-call total-timeout wrapper for one MCP tool. A fresh AbortController +
+ * timer bounds the call; it is composed with the turn's abortSignal via
+ * AbortSignal.any so EITHER the per-call timeout OR a client disconnect aborts
+ * the call. We RACE the call against the composed abort signal rather than just
+ * awaiting it, because @ai-sdk/mcp does NOT settle its in-flight promise on abort
+ * (verified in @ai-sdk/mcp@1.0.52: request() only does throwIfAborted() once
+ * before send and only re-checks the signal inside the response-message handler,
+ * which runs ONLY when a response arrives). So for a warm-but-stuck call awaiting
+ * `original` alone would hang forever even after the timer aborts.
+ */
+export function wrapToolWithCallTimeout(tool: Tool, ms: number): Tool {
+  const original = tool.execute;
+  if (typeof original !== 'function') return tool;
+  const execute = async (args: unknown, options: ToolCallOptions) => {
+    const controller = new AbortController();
+    const timer = setTimeout(() => {
+      controller.abort(new Error(`MCP tool call timed out after ${ms}ms`));
+    }, ms);
+    timer.unref?.();
+    const abortSignal = options?.abortSignal
+      ? AbortSignal.any([options.abortSignal, controller.signal])
+      : controller.signal;
+    // Reject as soon as the composed signal fires, independent of whether
+    // `original` ever settles. The losing `original` promise is left pending; it
+    // is cleaned up when the client is closed at turn end, and Promise.race
+    // attaches a rejection handler to BOTH inputs so a late rejection of either
+    // is never an unhandled rejection (do NOT add an extra .catch — it could
+    // swallow the real result and would break the race semantics).
+    const aborted = new Promise<never>((_, reject) => {
+      const fail = () => reject(abortReason(abortSignal));
+      if (abortSignal.aborted) fail();
+      else abortSignal.addEventListener('abort', fail, { once: true });
+    });
+    try {
+      return await Promise.race([
+        original(args, { ...options, abortSignal }),
+        aborted,
+      ]);
+    } finally {
+      clearTimeout(timer);
+    }
+  };
+  // `Tool` is a union whose `execute` overloads conflict; cast narrowly so the
+  // wrapped tool keeps every other field while swapping only `execute`.
+  return { ...tool, execute } as unknown as Tool;
+}
+
+/** The signal's reason as an Error (informative thrown value on abort/timeout). */
+function abortReason(signal: AbortSignal): Error {
+  const r = signal.reason;
+  return r instanceof Error
+    ? r
+    : new Error(typeof r === 'string' ? r : 'MCP tool call aborted');
+}
+
 /** Reject a promise after `ms`, so a hung connect/tools() never stalls a turn. */
 function withTimeout<T>(promise: Promise<T>, ms: number): Promise<T> {
   return new Promise<T>((resolve, reject) => {

apps/server/src/core/ai-chat/public-share-chat.service.ts

@@ -244,6 +244,15 @@ export class PublicShareChatService {
         },
       });
 
+      // Drain the stream independently of the client socket so the turn always
+      // runs to completion (or to its abort) even when the anonymous client
+      // disconnects — otherwise the dead socket is the only reader, backpressure
+      // stalls the stream, and the per-turn object graph stays rooted (heap-OOM
+      // leak). consumeStream removes that backpressure (AI SDK v6 "Handling
+      // client disconnects"). Fire-and-forget; stream errors are already logged
+      // by the streamText `onError` callback above.
+      void result.consumeStream({ onError: () => undefined });
+
       // Stream the UI-message protocol straight to the hijacked Node response.
       // Surface the real provider message (AI SDK error bodies never carry the
       // API key, so this is safe; we never dump the resolved config).

apps/server/src/database/migrations/20260626T120000-ai-chat-message-status.ts

@@ -0,0 +1,18 @@
+import { type Kysely } from 'kysely';
+
+export async function up(db: Kysely<any>): Promise<void> {
+  // Step-granular durability for the assistant turn (#183). The assistant row is
+  // now created UPFRONT (status 'streaming') and UPDATEd as each step completes,
+  // so a process death mid-turn no longer loses the whole answer. The column is
+  // NULLABLE on purpose: rows written before this migration carry NULL, which the
+  // app treats as 'completed' (a settled, pre-status message). Values written by
+  // the app: 'streaming' | 'completed' | 'error' | 'aborted'.
+  await db.schema
+    .alterTable('ai_chat_messages')
+    .addColumn('status', 'text', (col) => col)
+    .execute();
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await db.schema.alterTable('ai_chat_messages').dropColumn('status').execute();
+}

apps/server/src/database/repos/ai-chat/ai-chat-message.repo.ts

@@ -1,4 +1,4 @@
-import { Injectable } from '@nestjs/common';
+import { Injectable, Logger } from '@nestjs/common';
 import { InjectKysely } from 'nestjs-kysely';
 import { KyselyDB, KyselyTransaction } from '../../types/kysely.types';
 import { dbOrTx } from '../../utils';
@@ -9,8 +9,24 @@ import {
 import { PaginationOptions } from '@docmost/db/pagination/pagination-options';
 import { executeWithCursorPagination } from '@docmost/db/pagination/cursor-pagination';
 
+// Crash-recovery sweep recency threshold (#183 review): a 'streaming' row is
+// only swept to 'aborted' once it has been UNTOUCHED for this long. A live turn
+// bumps `updatedAt` on every step (well under this window), so its row never
+// matches; only a turn whose process truly died (no step update for >threshold)
+// is swept. Chosen safely ABOVE the longest realistic turn so a fresh replica's
+// boot-sweep can never abort a turn another replica is actively streaming
+// (multi-instance deploy).
+const SWEEP_STREAMING_STALE_MS = 10 * 60 * 1000; // 10 minutes
+
+// Hard upper bound on the rows materialized by `findAllByChat` (export path).
+// A generous cap so a pathologically huge chat cannot load an unbounded result
+// into memory; far above any realistic transcript length.
+const FIND_ALL_BY_CHAT_LIMIT = 5000;
+
 @Injectable()
 export class AiChatMessageRepo {
+  private readonly logger = new Logger(AiChatMessageRepo.name);
+
   constructor(@InjectKysely() private readonly db: KyselyDB) {}
 
   // The `tsv` column is a trigger-maintained tsvector used only for
@@ -25,6 +41,7 @@ export class AiChatMessageRepo {
     'content',
     'toolCalls',
     'metadata',
+    'status',
     'createdAt',
     'updatedAt',
     'deletedAt',
@@ -60,6 +77,46 @@ export class AiChatMessageRepo {
     });
   }
 
+  // Load ALL (non-deleted) messages of a chat in ascending chronological order
+  // (oldest -> newest), unpaginated. Used by the server-side Markdown export
+  // (#183), where the DB is the single source of truth and the whole transcript
+  // must be rendered in one pass (findByChat is cursor-paginated and would only
+  // return the first page).
+  //
+  // Hard-capped at FIND_ALL_BY_CHAT_LIMIT rows (a generous bound, far above any
+  // realistic transcript) so exporting a pathologically huge chat cannot
+  // materialize an unbounded result set in memory.
+  async findAllByChat(
+    chatId: string,
+    workspaceId: string,
+    // Injectable for tests so truncation can be exercised on a modest volume.
+    limit: number = FIND_ALL_BY_CHAT_LIMIT,
+  ): Promise<AiChatMessage[]> {
+    // Fetch newest-first (+1 to DETECT truncation), so on overflow we keep the
+    // NEWEST `limit` messages — the recent conversation matters most for an
+    // export — rather than silently dropping the tail (#183 review). Reverse back
+    // to chronological for rendering, like findRecent.
+    const rows = await this.db
+      .selectFrom('aiChatMessages')
+      .select(this.baseFields)
+      .where('chatId', '=', chatId)
+      .where('workspaceId', '=', workspaceId)
+      .where('deletedAt', 'is', null)
+      .orderBy('createdAt', 'desc')
+      .orderBy('id', 'desc')
+      .limit(limit + 1)
+      .execute();
+
+    if (rows.length > limit) {
+      rows.length = limit; // keep the newest `limit` (rows are newest-first here)
+      this.logger.warn(
+        `Chat ${chatId} export truncated to the newest ${limit} messages ` +
+          `(older messages omitted).`,
+      );
+    }
+    return rows.reverse();
+  }
+
   // Load the most RECENT `limit` messages for a chat and return them in
   // ascending chronological order (oldest -> newest), as the model expects.
   // `findByChat` returns the FIRST page ASC (the OLDEST messages), which loses
@@ -96,4 +153,68 @@ export class AiChatMessageRepo {
       .returning(this.baseFields)
       .executeTakeFirst();
   }
+
+  /**
+   * Update a single message in place by id + workspace (#183 step-granular
+   * durability). The assistant row is created UPFRONT (status 'streaming') and
+   * patched as each step completes, then finalized once on the terminal status.
+   * `updatedAt` is always bumped. Returns the updated row (baseFields) or
+   * undefined when no row matched (e.g. a foreign workspace / deleted row).
+   */
+  async update(
+    id: string,
+    workspaceId: string,
+    patch: Partial<{
+      content: string | null;
+      toolCalls: unknown;
+      metadata: unknown;
+      status: string | null;
+    }>,
+    opts?: { onlyIfStreaming?: boolean; trx?: KyselyTransaction },
+  ): Promise<AiChatMessage | undefined> {
+    const db = dbOrTx(this.db, opts?.trx);
+    let query = db
+      .updateTable('aiChatMessages')
+      .set({ ...(patch as Record<string, unknown>), updatedAt: new Date() })
+      .where('id', '=', id)
+      .where('workspaceId', '=', workspaceId);
+    // Concurrency guard (#183 review): a per-step 'streaming' update must NEVER
+    // overwrite a row the terminal callback already finalized. onStepFinish
+    // fires the streaming update fire-and-forget, so its UPDATE can land AFTER
+    // finalize on a DIFFERENT pool connection (commit order is not guaranteed).
+    // Scoping the streaming update to rows STILL in 'streaming' makes a late
+    // update a no-op once the row is completed/error/aborted — regardless of
+    // commit order. The terminal finalize runs WITHOUT this guard so it always
+    // wins.
+    if (opts?.onlyIfStreaming) {
+      query = query.where('status', '=', 'streaming');
+    }
+    return query.returning(this.baseFields).executeTakeFirst();
+  }
+
+  /**
+   * Crash-recovery sweep (#183): flip every assistant row still left in the
+   * 'streaming' state (a turn that died mid-write before reaching a terminal
+   * status) to 'aborted'. Run once on server start. Returns the number of rows
+   * swept so the caller can log it. Workspace-wide on purpose — a crash can have
+   * dangling streaming rows across any workspace.
+   *
+   * Bounded by recency (#183 review): only rows UNTOUCHED for
+   * SWEEP_STREAMING_STALE_MS are swept. A live turn bumps `updatedAt` on every
+   * step, so an actively-streaming row never matches; this prevents a fresh
+   * replica's boot-sweep from aborting a turn another replica is still streaming
+   * in a multi-instance deploy.
+   */
+  async sweepStreaming(trx?: KyselyTransaction): Promise<number> {
+    const db = dbOrTx(this.db, trx);
+    const staleBefore = new Date(Date.now() - SWEEP_STREAMING_STALE_MS);
+    const rows = await db
+      .updateTable('aiChatMessages')
+      .set({ status: 'aborted', updatedAt: new Date() })
+      .where('status', '=', 'streaming')
+      .where('updatedAt', '<', staleBefore)
+      .returning('id')
+      .execute();
+    return rows.length;
+  }
 }

apps/server/src/database/types/db.d.ts

@@ -620,6 +620,10 @@ export interface AiChatMessages {
   content: string | null;
   toolCalls: Json | null;
   metadata: Json | null;
+  // Turn lifecycle status (#183): 'streaming' | 'completed' | 'error' |
+  // 'aborted'. NULL on rows written before the status column existed; the app
+  // treats NULL as 'completed' (a settled, pre-status message).
+  status: string | null;
   tsv: string | null;
   createdAt: Generated<Timestamp>;
   updatedAt: Generated<Timestamp>;

apps/server/src/integrations/ai/ai-streaming-fetch.ts

@@ -70,6 +70,47 @@ export function streamKeepAliveMs(): number {
   return positiveEnv('AI_STREAM_KEEPALIVE_MS', DEFAULT_STREAM_KEEPALIVE_MS);
 }
 
+/** Default SILENCE timeout for EXTERNAL-MCP transport (5 min). */
+const DEFAULT_MCP_STREAM_TIMEOUT_MS = 300_000;
+
+/** Default total wall-clock cap for ONE external MCP tool call (15 min). */
+const DEFAULT_MCP_CALL_TIMEOUT_MS = 900_000;
+
+/**
+ * SILENCE timeout (ms) for EXTERNAL-MCP transport ONLY. Override with
+ * `AI_MCP_STREAM_TIMEOUT_MS`; a missing/invalid/non-positive value falls back to
+ * {@link DEFAULT_MCP_STREAM_TIMEOUT_MS} (5 min).
+ *
+ * Deliberately tighter than the chat provider's {@link streamTimeoutMs} (15 min)
+ * so a byte-silent/hung MCP upstream is broken in ~5 min instead of 15. This is
+ * the undici `headersTimeout`/`bodyTimeout` for the external-MCP dispatcher only
+ * — it must NOT change the chat provider, which legitimately needs 15 min between
+ * reasoning chunks (#175).
+ *
+ * Trade-off: a legitimately long but byte-silent single tool call (a slow crawl
+ * that emits nothing until done) and an SSE transport that idles >5 min BETWEEN
+ * tool calls are also cut here. The per-call total cap ({@link mcpCallTimeoutMs},
+ * applied in mcp-clients.service) is the complementary guard for chatty-but-stuck
+ * calls that keep the socket warm yet never return.
+ */
+export function mcpStreamTimeoutMs(): number {
+  return positiveEnv('AI_MCP_STREAM_TIMEOUT_MS', DEFAULT_MCP_STREAM_TIMEOUT_MS);
+}
+
+/**
+ * Total wall-clock cap (ms) for ONE external MCP tool call — APP-LEVEL, not
+ * transport. Override with `AI_MCP_CALL_TIMEOUT_MS`; a missing/invalid/
+ * non-positive value falls back to {@link DEFAULT_MCP_CALL_TIMEOUT_MS} (15 min).
+ *
+ * Catches a tool that keeps the connection warm (SSE heartbeats / trickle) but
+ * never returns a result — which the transport silence timeout
+ * ({@link mcpStreamTimeoutMs}) would never break because the socket never goes
+ * byte-silent.
+ */
+export function mcpCallTimeoutMs(): number {
+  return positiveEnv('AI_MCP_CALL_TIMEOUT_MS', DEFAULT_MCP_CALL_TIMEOUT_MS);
+}
+
 /**
  * undici `Agent` options for streaming AI traffic — the (generous, finite)
  * silence timeouts plus the keep-alive recycle window. Shared by the chat

apps/server/test/integration/ai-chat-message-status.int-spec.ts

@@ -0,0 +1,270 @@
+import { Kysely } from 'kysely';
+import { AiChatMessageRepo } from '@docmost/db/repos/ai-chat/ai-chat-message.repo';
+import {
+  getTestDb,
+  destroyTestDb,
+  createWorkspace,
+  createUser,
+  createChat,
+  createMessage,
+} from './db';
+
+/**
+ * Integration coverage for the #183 step-granular durability primitives on
+ * AiChatMessageRepo: `update` (in-place patch by id+workspace, bumps updatedAt,
+ * returns the row) and `sweepStreaming` (crash recovery: flip dangling
+ * 'streaming' rows to 'aborted'). Real SQL against docmost_test, not a mock.
+ */
+describe('AiChatMessageRepo.update + sweepStreaming [integration]', () => {
+  let db: Kysely<any>;
+  let repo: AiChatMessageRepo;
+  let workspaceId: string;
+  let otherWorkspaceId: string;
+  let userId: string;
+  let chatId: string;
+  let otherChatId: string;
+
+  beforeAll(async () => {
+    db = getTestDb();
+    repo = new AiChatMessageRepo(db as any);
+    workspaceId = (await createWorkspace(db)).id;
+    otherWorkspaceId = (await createWorkspace(db)).id;
+    userId = (await createUser(db, workspaceId)).id;
+    chatId = (await createChat(db, { workspaceId, creatorId: userId })).id;
+    const otherUser = await createUser(db, otherWorkspaceId);
+    otherChatId = (
+      await createChat(db, {
+        workspaceId: otherWorkspaceId,
+        creatorId: otherUser.id,
+      })
+    ).id;
+  });
+
+  afterAll(async () => {
+    await destroyTestDb();
+  });
+
+  it('update patches content/status/metadata and bumps updatedAt', async () => {
+    const seeded = await repo.insert({
+      chatId,
+      workspaceId,
+      userId,
+      role: 'assistant',
+      content: '',
+      status: 'streaming',
+      metadata: { parts: [] } as never,
+    });
+    const before = seeded.updatedAt;
+    // Ensure a measurable timestamp delta.
+    await new Promise((r) => setTimeout(r, 5));
+
+    const updated = await repo.update(seeded.id, workspaceId, {
+      content: 'final answer',
+      status: 'completed',
+      metadata: { parts: [{ type: 'text', text: 'final answer' }] },
+    });
+
+    expect(updated).toBeDefined();
+    expect(updated!.content).toBe('final answer');
+    expect(updated!.status).toBe('completed');
+    expect((updated!.metadata as any).parts).toHaveLength(1);
+    // The 5ms sleep above guarantees a strictly-later timestamp.
+    expect(new Date(updated!.updatedAt).getTime()).toBeGreaterThan(
+      new Date(before).getTime(),
+    );
+  });
+
+  it('onlyIfStreaming update is a NO-OP once the row is finalized (race guard)', async () => {
+    // Reproduce the step-update-vs-finalize race (#183 review): the row is
+    // finalized to 'completed', then a LATE per-step 'streaming' update lands.
+    // With `onlyIfStreaming` it must match nothing and leave the finalized row
+    // untouched (no clobber back to 'streaming', no lost usage).
+    const seeded = await repo.insert({
+      chatId,
+      workspaceId,
+      userId,
+      role: 'assistant',
+      content: 'partial',
+      status: 'streaming',
+    });
+    // Terminal finalize (unguarded) wins.
+    await repo.update(seeded.id, workspaceId, {
+      content: 'final answer',
+      status: 'completed',
+      metadata: { usage: { totalTokens: 42 } } as never,
+    });
+    // A straggler per-step update arrives AFTER finalize.
+    const late = await repo.update(
+      seeded.id,
+      workspaceId,
+      { content: 'partial', status: 'streaming', metadata: {} as never },
+      { onlyIfStreaming: true },
+    );
+    expect(late).toBeUndefined(); // matched no 'streaming' row -> no-op
+    const rows = await repo.findAllByChat(chatId, workspaceId);
+    const row = rows.find((r) => r.id === seeded.id)!;
+    expect(row.status).toBe('completed'); // NOT clobbered back to streaming
+    expect(row.content).toBe('final answer');
+    expect((row.metadata as any).usage.totalTokens).toBe(42); // usage preserved
+  });
+
+  it('update is workspace-scoped: a foreign workspace id matches nothing', async () => {
+    const seeded = await repo.insert({
+      chatId,
+      workspaceId,
+      userId,
+      role: 'assistant',
+      content: 'orig',
+      status: 'streaming',
+    });
+    const res = await repo.update(seeded.id, otherWorkspaceId, {
+      status: 'completed',
+    });
+    expect(res).toBeUndefined();
+    // The row in the real workspace is untouched.
+    const rows = await repo.findAllByChat(chatId, workspaceId);
+    const stillThere = rows.find((r) => r.id === seeded.id);
+    expect(stillThere!.status).toBe('streaming');
+    // Clean up so it does not pollute the sweep test below.
+    await repo.update(seeded.id, workspaceId, { status: 'completed' });
+  });
+
+  // Backdate a row's updatedAt so it qualifies as a STALE streaming row (the
+  // sweep only flips rows untouched for >10 minutes — a live turn bumps
+  // updatedAt every step, so it would never match).
+  async function backdateUpdatedAt(
+    id: string,
+    minutesAgo: number,
+  ): Promise<void> {
+    await db
+      .updateTable('aiChatMessages')
+      .set({ updatedAt: new Date(Date.now() - minutesAgo * 60 * 1000) })
+      .where('id', '=', id)
+      .execute();
+  }
+
+  it('sweepStreaming flips STALE dangling streaming rows to aborted and counts them', async () => {
+    // Two dangling streaming rows in our workspace + one in another workspace —
+    // all backdated past the staleness threshold so the sweep picks them up.
+    const a = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: 'streaming',
+    });
+    const b = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: 'streaming',
+    });
+    const other = await createMessage(db, {
+      workspaceId: otherWorkspaceId,
+      chatId: otherChatId,
+      role: 'assistant',
+      status: 'streaming',
+    });
+    await backdateUpdatedAt(a.id, 20);
+    await backdateUpdatedAt(b.id, 20);
+    await backdateUpdatedAt(other.id, 20);
+
+    // A settled row must NOT be touched.
+    const done = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: 'completed',
+    });
+    // A legacy NULL-status row must NOT be touched.
+    const legacy = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: null,
+    });
+
+    const swept = await repo.sweepStreaming();
+    // At least the 3 stale streaming rows we created (2 here + 1 in the other ws).
+    expect(swept).toBeGreaterThanOrEqual(3);
+
+    const rows = await repo.findAllByChat(chatId, workspaceId);
+    const byId = new Map(rows.map((r) => [r.id, r]));
+    expect(byId.get(a.id)!.status).toBe('aborted');
+    expect(byId.get(b.id)!.status).toBe('aborted');
+    expect(byId.get(done.id)!.status).toBe('completed');
+    expect(byId.get(legacy.id)!.status).toBeNull();
+
+    // Idempotent: a second sweep finds nothing left in our seeded set.
+    const again = await repo.sweepStreaming();
+    const rows2 = await repo.findAllByChat(chatId, workspaceId);
+    // Our two rows stay aborted regardless of `again`'s global count.
+    expect(rows2.find((r) => r.id === a.id)!.status).toBe('aborted');
+    expect(again).toBeGreaterThanOrEqual(0);
+  });
+
+  it('sweepStreaming does NOT sweep a FRESH streaming row (recency bound, #183 review)', async () => {
+    // A row that is actively streaming (recent updatedAt) must survive the sweep:
+    // a fresh replica's boot-sweep must never abort a turn another replica is
+    // still streaming in a multi-instance deploy.
+    const fresh = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: 'streaming',
+    });
+    // A STALE streaming row created alongside it IS swept — proving the sweep
+    // ran and the only difference is recency.
+    const stale = await createMessage(db, {
+      workspaceId,
+      chatId,
+      role: 'assistant',
+      status: 'streaming',
+    });
+    await backdateUpdatedAt(stale.id, 20);
+
+    await repo.sweepStreaming();
+
+    const rows = await repo.findAllByChat(chatId, workspaceId);
+    const byId = new Map(rows.map((r) => [r.id, r]));
+    // Fresh (recently-updated) streaming row is left untouched...
+    expect(byId.get(fresh.id)!.status).toBe('streaming');
+    // ...while the stale one alongside it was swept to 'aborted'.
+    expect(byId.get(stale.id)!.status).toBe('aborted');
+  });
+
+  it('findAllByChat caps the result, keeping the NEWEST messages in order (#183 review)', async () => {
+    // A dedicated chat so the cap test is independent of the rows above.
+    const cappedChat = (
+      await createChat(db, { workspaceId, creatorId: userId })
+    ).id;
+    const base = Date.now();
+    // Three messages at strictly increasing timestamps.
+    await createMessage(db, {
+      workspaceId,
+      chatId: cappedChat,
+      content: 'm1-oldest',
+      createdAt: new Date(base),
+    });
+    await createMessage(db, {
+      workspaceId,
+      chatId: cappedChat,
+      content: 'm2',
+      createdAt: new Date(base + 1000),
+    });
+    await createMessage(db, {
+      workspaceId,
+      chatId: cappedChat,
+      content: 'm3-newest',
+      createdAt: new Date(base + 2000),
+    });
+
+    // Cap of 2 -> the OLDEST message is dropped; the newest two stay, in
+    // chronological order (oldest -> newest).
+    const capped = await repo.findAllByChat(cappedChat, workspaceId, 2);
+    expect(capped.map((r) => r.content)).toEqual(['m2', 'm3-newest']);
+
+    // Without a cap (well above the row count) all three come back in order.
+    const all = await repo.findAllByChat(cappedChat, workspaceId, 100);
+    expect(all.map((r) => r.content)).toEqual(['m1-oldest', 'm2', 'm3-newest']);
+  });
+});

apps/server/test/integration/db.ts

@@ -104,7 +104,8 @@ export async function createWorkspace(
       name: overrides.name ?? `ws-${suffix}`,
       // hostname is uniquely constrained; keep it unique per workspace.
       hostname: `host-${suffix}`,
-      settings: overrides.settings === undefined ? null : (overrides.settings as any),
+      settings:
+        overrides.settings === undefined ? null : (overrides.settings as any),
     })
     .returning(['id', 'settings'])
     .executeTakeFirstOrThrow();
@@ -226,3 +227,37 @@ export async function createChat(
     .executeTakeFirstOrThrow();
   return { id: row.id as string };
 }
+
+export async function createMessage(
+  db: Kysely<any>,
+  args: {
+    workspaceId: string;
+    chatId: string;
+    userId?: string | null;
+    role?: string;
+    content?: string | null;
+    status?: string | null;
+    metadata?: unknown;
+    // Explicit timestamp so a test can control message ORDER (the default DB
+    // now() can tie within a millisecond, and the v4 id is not time-ordered).
+    createdAt?: Date;
+  },
+): Promise<{ id: string }> {
+  const id = randomUUID();
+  const row = await db
+    .insertInto('aiChatMessages')
+    .values({
+      id,
+      workspaceId: args.workspaceId,
+      chatId: args.chatId,
+      userId: args.userId ?? null,
+      role: args.role ?? 'assistant',
+      content: args.content ?? null,
+      status: args.status ?? null,
+      metadata: (args.metadata ?? null) as any,
+      ...(args.createdAt ? { createdAt: args.createdAt } : {}),
+    })
+    .returning(['id'])
+    .executeTakeFirstOrThrow();
+  return { id: row.id as string };
+}